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Sample records for hybrid actuation mechanism

  1. Mathematical model and characteristic analysis of hybrid photovoltaic/piezoelectric actuation mechanism

    Science.gov (United States)

    Jiang, Jing; Li, Xiaonan; Ding, Jincheng; Yue, Honghao; Deng, Zongquan

    2016-12-01

    Photovoltaic materials can turn light energy into electric energy directly, and thus have the advantages of high electrical output voltages and the ability to realize remote or non-contact control. When high-energy ultraviolet light illuminates polarized PbLaZrTi (PLZT) materials, high photovoltages will be generated along the spontaneous polarization direction due to the photovoltaic effect. In this paper, a novel hybrid photovoltaic/piezoelectric actuation mechanism is proposed. PLZT ceramics are used as a photovoltaic generator to drive a piezoelectric actuator. A mathematical model is established to define the time history of the actuation voltage between two electrodes of the piezoelectric actuator, which is experimentally validated by the test results of a piezoelectric actuator with different geometrical parameters under irradiation at different light intensities. Some important characteristics of this novel actuation mechanism are analyzed and it can be concluded that (1) it is experimentally validated that there is no hysteresis between voltage and deformation which exists in a PLZT actuator; (2) the saturated voltage and response speed can be improved by using a multi-patch PLZT generator to drive the piezoelectric actuator; and (3) the initial voltage of the piezoelectric actuator can be acquired by controlling the logical switch between the PLZT and the piezoelectric actuator while the initial voltages increase with the rise of light intensity.

  2. Soft-rigid interaction mechanism towards a lobster-inspired hybrid actuator

    Science.gov (United States)

    Chen, Yaohui; Wan, Fang; Wu, Tong; Song, Chaoyang

    2018-01-01

    Soft pneumatic actuators (SPAs) are intrinsically light-weight, compliant and therefore ideal to directly interact with humans and be implemented into wearable robotic devices. However, they also pose new challenges in describing and sensing their continuous deformation. In this paper, we propose a hybrid actuator design with bio-inspirations from the lobsters, which can generate reconfigurable bending movements through the internal soft chamber interacting with the external rigid shells. This design with joint and link structures enables us to exactly track its bending configurations that previously posed a significant challenge to soft robots. Analytic models are developed to illustrate the soft-rigid interaction mechanism with experimental validation. A robotic glove using hybrid actuators to assist grasping is assembled to illustrate their potentials in safe human-robot interactions. Considering all the design merits, our work presents a practical approach to the design of next-generation robots capable of achieving both good accuracy and compliance.

  3. A novel hybrid actuation mechanism based XY nanopositioning stage with totally decoupled kinematics

    Science.gov (United States)

    Zhu, Wu-Le; Zhu, Zhiwei; Guo, Ping; Ju, Bing-Feng

    2018-01-01

    This paper reports the design, analysis and testing of a parallel two degree-of-freedom piezo-actuated compliant stage for XY nanopositioning by introducing an innovative hybrid actuation mechanism. It mainly features the combination of two Scott-Russell and a half-bridge mechanisms for double-stage displacement amplification as well as moving direction modulation. By adopting the leaf-type double parallelogram (LTDP) structures at both input and output ends of the hybrid mechanism, the lateral stiffness and dynamic characteristics are significantly improved while the parasitic motions are greatly eliminated. The XY nanopositioning stage is constructed with two orthogonally configured hybrid mechanisms along with the LTDP mechanisms for totally decoupled kinematics at both input and output ends. An analytical model was established to describe the complete elastic deformation behavior of the stage, with further verification through the finite element simulation. Finally, experiments were implemented to comprehensively evaluate both the static and dynamic performances of the proposed stage. Closed-loop control of the piezoelectric actuators (PEA) by integrating strain gauges was also conducted to effectively eliminate the nonlinear hysteresis of the stage.

  4. Hybrid nanocomposites based on electroactive hydrogels and cellulose nanocrystals for high-sensitivity electro-mechanical underwater actuation

    Science.gov (United States)

    Santaniello, Tommaso; Migliorini, Lorenzo; Locatelli, Erica; Monaco, Ilaria; Yan, Yunsong; Lenardi, Cristina; Comes Franchini, Mauro; Milani, Paolo

    2017-08-01

    We report the synthesis, fabrication and characterization of a hybrid hydrogel/cellulose nanocomposite, which exhibits high-performance electro-mechanical underwater actuation and high sensitivity in response to electrical stimuli below the standard potential of water electrolysis. The macromolecular structure of the material is constituted by an electroactive hydrogel, obtained through a photo-polymerization reaction with the use of three vinylic co-monomers: Na-4-vinylbenzenesulfonate, 2-hydroxyethylmethacrylate, and acrylonitrile. Different amounts (from 0.1% to 1.4% w/w) of biodegradable cellulose nanocrystals (CNCs) with sulfonate surface groups, obtained through the acidic hydrolysis of sulphite pulp lapsheets, are physically incorporated into the gel matrix during the synthesis step. Freestanding thin films of the nanocomposites are molded, and their swelling, mechanical and responsive properties are fully characterized. We observed that the embedding of the CNCs enhanced both the material Young’s modulus and its sensitivity to the applied electric field in the sub-volt regime (down to 5 mV cm-1). A demonstrator integrating multiple actuators that cooperatively bend together, mimicking the motion of an electro-valve, is also prototyped and tested. The presented nanocomposite is suitable for the development of soft smart components for bio-robotic applications and cells-based and bio-hybrid fluidic devices fabrication.

  5. Hybrid Multi-Physics Modeling of an Ultra-Fast Electro-Mechanical Actuator

    Directory of Open Access Journals (Sweden)

    Ara Bissal

    2015-12-01

    Full Text Available The challenges of an HVDC breaker are to generate impulsive forces in the order of hundreds of kilonewtons within fractions of a millisecond, to withstand the arising internal mechanical stresses and to transmit these forces via an electrically-insulating device to the contact system with minimum time delay. In this work, several models were developed with different levels of complexity, computation time and accuracy. Experiments were done with two mushroom-shaped armatures to validate the developed simulation models. It was concluded that although the electromagnetic force generation mechanism is highly sensitive to the mechanical response of the system, the developed first order hybrid model is able to predict the performance of the breaker with good accuracy.

  6. Paper actuators made with cellulose and hybrid materials.

    Science.gov (United States)

    Kim, Jaehwan; Yun, Sungryul; Mahadeva, Suresha K; Yun, Kiju; Yang, Sang Yeol; Maniruzzaman, Mohammad

    2010-01-01

    Recently, cellulose has been re-discovered as a smart material that can be used as sensor and actuator materials, which is termed electro-active paper (EAPap). This paper reports recent advances in paper actuators made with cellulose and hybrid materials such as multi-walled carbon nanotubes, conducting polymers and ionic liquids. Two distinct actuator principles in EAPap actuators are demonstrated: piezoelectric effect and ion migration effect in cellulose. Piezoelectricity of cellulose EAPap is quite comparable with other piezoelectric polymers. But, it is biodegradable, biocompatible, mechanically strong and thermally stable. To enhance ion migration effect in the cellulose, polypyrrole conducting polymer and ionic liquids were nanocoated on the cellulose film. This hybrid cellulose EAPap nanocomposite exhibits durable bending actuation in an ambient humidity and temperature condition. Fabrication, characteristics and performance of the cellulose EAPap and its hybrid EAPap materials are illustrated. Also, its possibility for remotely microwave-driven paper actuator is demonstrated.

  7. Three-dimensional graphene-polypyrrole hybrid electrochemical actuator

    Science.gov (United States)

    Liu, Jia; Wang, Zhi; Zhao, Yang; Cheng, Huhu; Hu, Chuangang; Jiang, Lan; Qu, Liangti

    2012-11-01

    The advancement of mechanical actuators benefits from the development of new structural materials with prominent properties. A novel three-dimensional (3D) hydrothermally converted graphene and polypyrrole (G-PPy) hybrid electrochemical actuator is presented, which is prepared via a convenient hydrothermal process, followed by in situ electropolymerization of pyrrole. The 3D pore-interconnected G-PPy pillar exhibits strong actuation responses superior to pure graphene and PPy film. In response to the low potentials of +/-0.8 V, the saturated strain of 3D G-PPy pillar can reach a record of 2.5%, which is more than 10 times higher than that of carbon nanotube film and about 3 times that of unitary graphene film under an applied potential of +/-1.2 V. Also, the 3D G-PPy actuator exhibits high actuation durability with high operating load as demonstrated by an 11 day continuous measurement. Finally, a proof-of-concept application of 3D G-PPy as smart filler for on/off switch is also demonstrated, which indicates the great potential of the 3D G-PPy structure developed in this study for advanced actuator systems.The advancement of mechanical actuators benefits from the development of new structural materials with prominent properties. A novel three-dimensional (3D) hydrothermally converted graphene and polypyrrole (G-PPy) hybrid electrochemical actuator is presented, which is prepared via a convenient hydrothermal process, followed by in situ electropolymerization of pyrrole. The 3D pore-interconnected G-PPy pillar exhibits strong actuation responses superior to pure graphene and PPy film. In response to the low potentials of +/-0.8 V, the saturated strain of 3D G-PPy pillar can reach a record of 2.5%, which is more than 10 times higher than that of carbon nanotube film and about 3 times that of unitary graphene film under an applied potential of +/-1.2 V. Also, the 3D G-PPy actuator exhibits high actuation durability with high operating load as demonstrated by an 11 day

  8. Hybrid-Actuated Finger Prosthesis with Tactile Sensing

    Directory of Open Access Journals (Sweden)

    Cheng Yee Low

    2013-10-01

    Full Text Available Finger prostheses are devices developed to emulate the functionality of natural human fingers. On top of their aesthetic appearance in terms of shape, size and colour, such biomimetic devices require a high level of dexterity. They must be capable of gripping an object, and even manipulating it in the hand. This paper presents a biomimetic robotic finger actuated by a hybrid mechanism and integrated with a tactile sensor. The hybrid actuation mechanism comprises a DC micromotor and a Shape Memory Alloy (SMA wire. A customized test rig has been developed to measure the force and stroke produced by the SMA wire. In parallel with the actuator development, experimental investigations have been conducted on Quantum Tunnelling Composite (QTC and Pressure Conductive Rubber (PCR towards the development of a tactile sensor for the finger. The viability of using these materials for tactile sensing has been determined. Such a hybrid actuation approach aided with tactile sensing capability enables a finger design as an integral part of a prosthetic hand for applications up to the transradial amputation level.

  9. Modeling and design of a high-performance hybrid actuator

    Science.gov (United States)

    Aloufi, Badr; Behdinan, Kamran; Zu, Jean

    2016-12-01

    This paper presents the model and design of a novel hybrid piezoelectric actuator which provides high active and passive performances for smart structural systems. The actuator is composed of a pair of curved pre-stressed piezoelectric actuators, so-called commercially THUNDER actuators, installed opposite each other using two clamping mechanisms constructed of in-plane fixable hinges, grippers and solid links. A fully mathematical model is developed to describe the active and passive dynamics of the actuator and investigate the effects of its geometrical parameters on the dynamic stiffness, free displacement and blocked force properties. Among the literature that deals with piezoelectric actuators in which THUNDER elements are used as a source of electromechanical power, the proposed study is unique in that it presents a mathematical model that has the ability to predict the actuator characteristics and achieve other phenomena, such as resonances, mode shapes, phase shifts, dips, etc. For model validation, the measurements of the free dynamic response per unit voltage and passive acceleration transmissibility of a particular actuator design are used to check the accuracy of the results predicted by the model. The results reveal that there is a good agreement between the model and experiment. Another experiment is performed to teste the linearity of the actuator system by examining the variation of the output dynamic responses with varying forces and voltages at different frequencies. From the results, it can be concluded that the actuator acts approximately as a linear system at frequencies up to 1000 Hz. A parametric study is achieved here by applying the developed model to analyze the influence of the geometrical parameters of the fixable hinges on the active and passive actuator properties. The model predictions in the frequency range of 0-1000 Hz show that the hinge thickness, radius, and opening angle parameters have great effects on the frequency dynamic

  10. Bioinspired Smart Actuator Based on Graphene Oxide-Polymer Hybrid Hydrogels.

    Science.gov (United States)

    Wang, Tao; Huang, Jiahe; Yang, Yiqing; Zhang, Enzhong; Sun, Weixiang; Tong, Zhen

    2015-10-28

    Rapid response and strong mechanical properties are desired for smart materials used in soft actuators. A bioinspired hybrid hydrogel actuator was designed and prepared by series combination of three trunks of tough polymer-clay hydrogels to accomplish the comprehensive actuation of "extension-grasp-retraction" like a fishing rod. The hydrogels with thermo-creep and thermo-shrinking features were successively irradiated by near-infrared (NIR) to execute extension and retraction, respectively. The GO in the hydrogels absorbed the NIR energy and transformed it into thermo-energy rapidly and effectively. The hydrogel with adhesion or magnetic force was adopted as the "hook" of the hybrid hydrogel actuator for grasping object. The hook of the hybrid hydrogel actuator was replaceable according to applications, even with functional materials other than hydrogels. This study provides an innovative concept to explore new soft actuators through combining response hydrogels and programming the same stimulus.

  11. Paper Actuators Made with Cellulose and Hybrid Materials

    OpenAIRE

    Kim, Jaehwan; Yun, Sungryul; Mahadeva, Suresha K.; Yun, Kiju; Yang, Sang Yeol; Maniruzzaman, Mohammad

    2010-01-01

    Recently, cellulose has been re-discovered as a smart material that can be used as sensor and actuator materials, which is termed electro-active paper (EAPap). This paper reports recent advances in paper actuators made with cellulose and hybrid materials such as multi-walled carbon nanotubes, conducting polymers and ionic liquids. Two distinct actuator principles in EAPap actuators are demonstrated: piezoelectric effect and ion migration effect in cellulose. Piezoelectricity of cellulose EAPa...

  12. Environmentally responsive optical microstructured hybrid actuator assemblies and applications thereof

    Science.gov (United States)

    Aizenberg, Joanna; Aizenberg, Michael; Kim, Philseok

    2016-01-05

    Microstructured hybrid actuator assemblies in which microactuators carrying designed surface properties to be revealed upon actuation are embedded in a layer of responsive materials. The microactuators in a microactuator array reversibly change their configuration in response to a change in the environment without requiring an external power source to switch their optical properties.

  13. Temperature sensitive self-actuated scram mechanism

    International Nuclear Information System (INIS)

    Giuggio, N.; Noyes, R.C.; Zaman, S.U.

    1982-01-01

    This invention provides a mechanism for rapidly dropping a neutron absorbing poison material into the core of an LMFBR type reactor, and in particular a mechanism that is self-actuated when the reactor coolant temperature reaches a critical value. A safety duct located in the reactor core and extending above the core contains an inner column that provides a vertical coolant flow path through the duct. One or more fuel pins are located in the duct, with a temperature-responsive actuator near their upper ends. A poison bundle surrounds the inner column within the duct, held in position by a release mechanism connected to the actuator. The inferred core temperature is sensed by a fluid confined within the actuator, and the expansion of the fluid is translated into a linear force used to activate the release mechanism

  14. Full Piezoelectric Multilayer-Stacked Hybrid Actuation/Transduction Systems

    Science.gov (United States)

    Su, Ji; Jiang, Xiaoning; Zu, Tian-Bing

    2011-01-01

    The Stacked HYBATS (Hybrid Actuation/Transduction system) demonstrates significantly enhanced electromechanical performance by using the cooperative contributions of the electromechanical responses of multilayer, stacked negative strain components and positive strain components. Both experimental and theoretical studies indicate that, for Stacked HYBATS, the displacement is over three times that of a same-sized conventional flextensional actuator/transducer. The coupled resonance mode between positive strain and negative strain components of Stacked HYBATS is much stronger than the resonance of a single element actuation only when the effective lengths of the two kinds of elements match each other. Compared with the previously invented hybrid actuation system (HYBAS), the multilayer Stacked HYBATS can be designed to provide high mechanical load capability, low voltage driving, and a highly effective piezoelectric constant. The negative strain component will contract, and the positive strain component will expand in the length directions when an electric field is applied on the device. The interaction between the two elements makes an enhanced motion along the Z direction for Stacked-HYBATS. In order to dominate the dynamic length of Stacked-HYBATS by the negative strain component, the area of the cross-section for the negative strain component will be much larger than the total cross-section areas of the two positive strain components. The transverse strain is negative and longitudinal strain positive in inorganic materials, such as ceramics/single crystals. Different piezoelectric multilayer stack configurations can make a piezoelectric ceramic/single-crystal multilayer stack exhibit negative strain or positive strain at a certain direction without increasing the applied voltage. The difference of this innovation from the HYBAS is that all the elements can be made from one-of-a-kind materials. Stacked HYBATS can provide an extremely effective piezoelectric

  15. Temperature sensitive self-actuated scram mechanism

    International Nuclear Information System (INIS)

    Giuggio, N.; Noyes, R.C.; Zaman, S.U.

    1980-01-01

    A self-actuated mechanism within a safety assembly in a liquid metal nuclear reactor comprising sensor fuel pins located in a reactor coolant flow path, a sensor bulb containing NaK located near the upper end of the sensor fuel pins and in the reactor coolant flow path, and a sensor tube connecting the sensor bulb to a metal bellows and push rod. The motion of the push rod resulting from the temperature dependent change in the NaK volume actuates a safety rod release mechanism when a predetermined coolant temperature is reached

  16. A Hybrid Extended Kalman Filter as an Observer for a Pot-Electro-Magnetic Actuator

    International Nuclear Information System (INIS)

    Schmidt, Simon; Mercorelli, Paolo

    2017-01-01

    This paper deals with an application in which a hybrid extended Kalman Filter (HEKF) is used to estimate state variables in a U-shaped electro-magnetic actuator to be used in mechanical systems. In this context a hybrid Kalman Filter is the one which switches between different models. The paper proposes a hybrid model for an extended Kalman Filter to be used as an observer to estimate the state and to control the force of the actuator. Applications include position, velocity and force control in automotive, engine and manufacturing systems. This work is focused on the estimation of state variables of the actuator. Simulated results show the effectiveness of the proposed approach. (paper)

  17. Temperature sensitive self-actuated scram mechanism

    International Nuclear Information System (INIS)

    1980-01-01

    The apparatus, described in detail, accurately infers the average coolant temperature exiting from the reactor core in a liquid metal cooled reactor and rapidly and reliably actuates a safety rod release mechanism on the occurrence of a critical temperature. The output temperature is inferred from the cooperative effect of the flow rate through a coolant flow path within the safety assembly and the heat generated by sensor fuel pins. The inferred temperature is sensed by a confined fluid having a high expansion coefficient; the expansion is transferred to a linear force used to actuate the release mechanism. The system may be contained within the safety assembly and does not interfere with the operation of the plant protection system scram mode. It is resetable after a scram. The time interval between the overtemperature and the insertion of the safety rods is short enough to preclude fuel damage. (U.K.)

  18. Mechanisms and actuators for rotorcraft blade morphing

    Science.gov (United States)

    Vocke, Robert D., III

    The idea of improved fight performance through changes in the control surfaces dates back to the advent of aviation with the Wright brothers' pioneering work on "wing warping," but it was not until the recent progress in material and actuator development that such control surfaces seemed practical for modern aircraft. This has opened the door to a new class of aircraft that have the ability to change shape or morph, which are being investigated due to the potential to have a single platform serve multiple mission objectives, as well as improve performance characteristics. While the majority of existing research for morphing aircraft has focused on fixedwing aircraft, rotary-wing aircraft have begun to receive more attention. The purpose of this body of work is to investigate the current state of morphing actuation technology for rotorcraft and improve upon it. Specifically, this work looks at two types of morphing: Pneumatic Artificial Muscle (PAM) actuated trailing edge flaps and conformal variable diameter morphing. First, active camber changes through the use of PAM powered trailing edge flaps were investigated due to the potential for reductions in power requirements and vibration/noise levels. A PAM based antagonistic actuation system was developed utilizing a novel combination of mechanism geometry and PAM bias contraction optimization to overcome the natural extension stiffening characteristics of PAMs. In open-loop bench-top testing against a "worst-case" constant torsional loading, the system demonstrated actuation authority suitable for both primary control and vibration/noise reduction. Additionally, closed-loop test data indicated that the system was capable of tracking complex waveforms consistent with those needed for rotorcraft control. This system demonstrated performance on-par with the state of the art pneumatic trailing edge flap actuators, yet with a much smaller footprint and impact on the rotor-blade. The second morphing system developed in

  19. Design and control of hybrid actuation lower limb exoskeleton

    Directory of Open Access Journals (Sweden)

    Hipolito Aguilar-Sierra

    2015-06-01

    Full Text Available In this article, two types of actuators are applied for a lower limb exoskeleton. They are DC motors with the harmonic drive and the pneumatic artificial muscles. This combination takes advantages of both the harmonic drive and the pneumatic artificial muscle. It provides both high accuracy position control and high ratio of strength and weight. The shortcomings of the two actuators are overcome by the hybrid actuation, for example, low control accuracy and modeling difficult of pneumatic artificial muscle, compactness, and structural flexibility of DC motors. The design and modeling processes are discussed to show the proposed exoskeleton can increase the strength of human lower limbs. Experiments and analysis of the exoskeleton are given to evaluate the effectiveness of the design and modeling.

  20. Design, test and model of a hybrid magnetostrictive hydraulic actuator

    International Nuclear Information System (INIS)

    Chaudhuri, Anirban; Yoo, Jin-Hyeong; Wereley, Norman M

    2009-01-01

    The basic operation of hybrid hydraulic actuators involves high frequency bi-directional operation of an active material that is converted to uni-directional motion of hydraulic fluid using valves. A hybrid actuator was developed using magnetostrictive material Terfenol-D as the driving element and hydraulic oil as the working fluid. Two different lengths of Terfenol-D rod, 51 and 102 mm, with the same diameter, 12.7 mm, were used. Tests with no load and with load were carried out to measure the performance for uni-directional motion of the output piston at different pumping frequencies. The maximum no-load flow rates were 24.8 cm 3 s −1 and 22.7 cm 3 s −1 with the 51 mm and 102 mm long rods respectively, and the peaks were noted around 325 Hz pumping frequency. The blocked force of the actuator was close to 89 N in both cases. A key observation was that, at these high pumping frequencies, the inertial effects of the fluid mass dominate over the viscous effects and the problem becomes unsteady in nature. In this study, we also develop a mathematical model of the hydraulic hybrid actuator in the time domain to show the basic operational principle under varying conditions and to capture phenomena affecting system performance. Governing equations for the pumping piston and output shaft were obtained from force equilibrium considerations, while compressibility of the working fluid was taken into account by incorporating the bulk modulus. Fluid inertia was represented by a lumped parameter approach to the transmission line model, giving rise to strongly coupled ordinary differential equations. The model was then used to calculate the no-load velocities of the actuator at different pumping frequencies and simulation results were compared with experimental data for model validation

  1. Mechatronic Design of a New Humanoid Robot with Hybrid Parallel Actuation

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    Vítor Santos

    2012-10-01

    Full Text Available Humanoid robotics is unquestionably a challenging and long-term field of research. Of the numerous and most urgent challenges to tackle, autonomous and efficient locomotion may possibly be the most underdeveloped at present in the research community. Therefore, to pursue studies in relation to autonomy with efficient locomotion, the authors have been developing a new teen-sized humanoid platform with hybrid characteristics. The hybrid nature is clear in the mixed actuation based on common electrical motors and passive actuators attached in parallel to the motors. This paper presents the mechatronic design of the humanoid platform, focusing mainly on the mechanical structure, the design and simulation of the hybrid joints, and the different subsystems implemented. Trying to keep the appropriate human proportions and main degrees of freedom, the developed platform utilizes a distributed control architecture and a rich set of sensing capabilities, both ripe for future development and research.

  2. A lightweight shoulder prosthesis with antagonistic impact-absorbing hybrid actuation for bimanual activities of daily living

    Directory of Open Access Journals (Sweden)

    Masashi Sekine

    2016-04-01

    Full Text Available In developing a shoulder prosthesis, in addition to appropriate payload and range of motion under the constraints of weight and shape, impact absorption is very important for safe use. Hybridization of two different actuators (pneumatic elastic actuators with the features of lightness and intrinsic visco-elasticity, and servo motors that have stable torque and a large range of motion in combination with an antagonistic mechanism was employed to achieve the development of the shoulder prosthesis. A two-link, two-degree-of-freedom arm was used to test the different hybridization configurations in order to investigate the impact absorption. A dynamic simulation platform based on four bimanual activities of daily living was established to obtain the required range of motion and torque for joints of a two-link, four-degree-of-freedom arm. The number of pneumatic elastic actuators required and the dimension of the antagonistic mechanism mechanical structures were optimized using the dynamic simulation platform. The best configuration of the two types of actuators was determined using the dynamic simulation based on the impact absorption results and other criteria. Moreover, a simplified prototype driven by hybrid actuation was made. It was shown that the pneumatic elastic actuator joint could improve impact absorption, and the actuator configuration of shoulder prostheses is activity of daily living dependent. The prototype could reproduce a certain activity of daily living motion, indicating its feasibility in daily living.

  3. Electrically, Chemically, and Photonically Powered Torsional and Tensile Actuation of Hybrid Carbon Nanotube Yarn Muscles

    Science.gov (United States)

    Lima, Márcio D.; Li, Na; Jung de Andrade, Mônica; Fang, Shaoli; Oh, Jiyoung; Spinks, Geoffrey M.; Kozlov, Mikhail E.; Haines, Carter S.; Suh, Dongseok; Foroughi, Javad; Kim, Seon Jeong; Chen, Yongsheng; Ware, Taylor; Shin, Min Kyoon; Machado, Leonardo D.; Fonseca, Alexandre F.; Madden, John D. W.; Voit, Walter E.; Galvão, Douglas S.; Baughman, Ray H.

    2012-11-01

    Artificial muscles are of practical interest, but few types have been commercially exploited. Typical problems include slow response, low strain and force generation, short cycle life, use of electrolytes, and low energy efficiency. We have designed guest-filled, twist-spun carbon nanotube yarns as electrolyte-free muscles that provide fast, high-force, large-stroke torsional and tensile actuation. More than a million torsional and tensile actuation cycles are demonstrated, wherein a muscle spins a rotor at an average 11,500 revolutions/minute or delivers 3% tensile contraction at 1200 cycles/minute. Electrical, chemical, or photonic excitation of hybrid yarns changes guest dimensions and generates torsional rotation and contraction of the yarn host. Demonstrations include torsional motors, contractile muscles, and sensors that capture the energy of the sensing process to mechanically actuate.

  4. Piezoelectric Multilayer-Stacked Hybrid Actuation/Transduction System

    Science.gov (United States)

    Xu, Tian-Bing (Inventor); Jiang, Xiaoning (Inventor); Su, Ji (Inventor)

    2014-01-01

    A novel full piezoelectric multilayer stacked hybrid actuation/transduction system. The system demonstrates significantly-enhanced electromechanical performance by utilizing the cooperative contributions of the electromechanical responses of multilayer stacked negative and positive strain components. Both experimental and theoretical studies indicate that for this system, the displacement is over three times that of a same-sized conventional flextensional actuator/transducer. The system consists of at least 2 layers which include electromechanically active components. The layers are arranged such that when electric power is applied, one layer contracts in a transverse direction while the second layer expands in a transverse direction which is perpendicular to the transverse direction of the first layer. An alternate embodiment includes a third layer. In this embodiment, the outer two layers contract in parallel transverse directions while the middle layer expands in a transverse direction which is perpendicular to the transverse direction of the outer layers.

  5. Development of X-Y servo pneumatic-piezoelectric hybrid actuators for position control with high response, large stroke and nanometer accuracy.

    Science.gov (United States)

    Chiang, Mao-Hsiung

    2010-01-01

    This study aims to develop a X-Y dual-axial intelligent servo pneumatic-piezoelectric hybrid actuator for position control with high response, large stroke (250 mm, 200 mm) and nanometer accuracy (20 nm). In each axis, the rodless pneumatic actuator serves to position in coarse stroke and the piezoelectric actuator compensates in fine stroke. Thus, the overall control systems of the single axis become a dual-input single-output (DISO) system. Although the rodless pneumatic actuator has relatively larger friction force, it has the advantage of mechanism for multi-axial development. Thus, the X-Y dual-axial positioning system is developed based on the servo pneumatic-piezoelectric hybrid actuator. In addition, the decoupling self-organizing fuzzy sliding mode control is developed as the intelligent control strategies. Finally, the proposed novel intelligent X-Y dual-axial servo pneumatic-piezoelectric hybrid actuators are implemented and verified experimentally.

  6. Development of X-Y Servo Pneumatic-Piezoelectric Hybrid Actuators for Position Control with High Response, Large Stroke and Nanometer Accuracy

    Directory of Open Access Journals (Sweden)

    Mao-Hsiung Chiang

    2010-03-01

    Full Text Available This study aims to develop a X-Y dual-axial intelligent servo pneumatic-piezoelectric hybrid actuator for position control with high response, large stroke (250 mm, 200 mm and nanometer accuracy (20 nm. In each axis, the rodless pneumatic actuator serves to position in coarse stroke and the piezoelectric actuator compensates in fine stroke. Thus, the overall control systems of the single axis become a dual-input single-output (DISO system. Although the rodless pneumatic actuator has relatively larger friction force, it has the advantage of mechanism for multi-axial development. Thus, the X-Y dual-axial positioning system is developed based on the servo pneumatic-piezoelectric hybrid actuator. In addition, the decoupling self-organizing fuzzy sliding mode control is developed as the intelligent control strategies. Finally, the proposed novel intelligent X-Y dual-axial servo pneumatic-piezoelectric hybrid actuators are implemented and verified experimentally.

  7. New ankle actuation mechanism for a humanoid robot

    NARCIS (Netherlands)

    van Oort, Gijs; Reinink, R.; Stramigioli, Stefano

    2011-01-01

    In this article we discuss the design of a new ankle actuation mechanism for the humanoid robot TUlip. The new mechanism consists of two coupled series-elastic systems. We discuss the choice of actuators according to calculations for maximum achievable walking speed. Some control issues, MIMO and

  8. Note: Hybrid active/passive force feedback actuator using hydrostatic transmission

    Science.gov (United States)

    Park, Yea-Seok; Lee, Juwon; Kim, Kyung-Soo; Kim, Soohyun

    2017-12-01

    A hybrid actuator for haptic devices is proposed in this paper. The actuator is composed of a DC motor and a magneto-rheological (MR) brake to realize transparency and stable force control. Two piston cylinders are connected with a flexible tube to lighten the weight of the structures on the endpoint that interacts with an operator. Also, the MR brake is designed to be suitable for hydraulic transmission. For the proposed hybrid actuator, a cooperative force control method using a pressure sensor instead of a force sensor is proposed. To verify the proposed control algorithm, a virtual wall collision experiment was conducted using a developed prototype of the hybrid actuator.

  9. Note: Hybrid active/passive force feedback actuator using hydrostatic transmission.

    Science.gov (United States)

    Park, Yea-Seok; Lee, Juwon; Kim, Kyung-Soo; Kim, Soohyun

    2017-12-01

    A hybrid actuator for haptic devices is proposed in this paper. The actuator is composed of a DC motor and a magneto-rheological (MR) brake to realize transparency and stable force control. Two piston cylinders are connected with a flexible tube to lighten the weight of the structures on the endpoint that interacts with an operator. Also, the MR brake is designed to be suitable for hydraulic transmission. For the proposed hybrid actuator, a cooperative force control method using a pressure sensor instead of a force sensor is proposed. To verify the proposed control algorithm, a virtual wall collision experiment was conducted using a developed prototype of the hybrid actuator.

  10. A rotary piezoelectric actuator using longitudinal and bending hybrid transducer

    Directory of Open Access Journals (Sweden)

    Yingxiang Liu

    2012-12-01

    Full Text Available A rotary piezoelectric actuator using bolt-clamped type transducer with double driving feet is proposed in this study. The first-order longitudinal and fourth-order bending vibration modes are superimposed in the actuator to produce elliptical movements on the driving tips. Longitudinal PZT and bending PZT are clamped between the exponential shape horns and the flange by bolts. The vibration shape changes of the actuator are presented to give a clear explanation of its working principle. Several structural parameters of the exponential shape horn are selected and adjusted to accomplish the tuning process of the longitudinal and bending resonance frequencies. The input impedance and vibration characteristics are calculated by using FEM method; the gained results verify the feasibility of the proposed actuator. After the fabrication of a prototype, its vibration characteristics are measured by using a scanning laser Doppler vibrometer; the tested results are in good agreement with the FEM calculated results. The mechanical output performance experiments state that the prototype achieves a maximum speed of 129 r/min and a maximum torque of 1.5 Nm.

  11. Micro-mechanics of ionic electroactive polymer actuators

    Science.gov (United States)

    Punning, Andres; Põldsalu, Inga; Kaasik, Friedrich; Vunder, Veiko; Aabloo, Alvo

    2015-04-01

    Commonly, modeling of the bending behavior of the ionic electroactive polymer (IEAP) actuators is based on the classical mechanics of cantilever beam. It is acknowledged, that the actuation of the ionic electroactive polymer (IEAP) actuators is symmetric about the centroid - the convex side of the actuator is expanding and the concave side is contracting for exactly the same amount, while the thickness of the actuator remains invariant. Actuating the IEAP actuators and sensors under scanning electron microscope (SEM), in situ, reveals that for some types of them this approach is incorrect. Comparison of the SEM micrographs using the Digital Image Correction (DIC) method results with the precise strain distribution of the IEAP actuators in two directions: in the axial direction, and in the direction of thickness. This information, in turn, points to the physical processes taking place within the electrodes as well as membrane of the trilayer laminate of sub-millimeter thickness. Comparison of the EAP materials, engaged as an actuator as well as a sensor, reveals considerable differences between the micro-mechanics of the two modes.

  12. Nonlinear Mechanics of MEMS Rectangular Microplates under Electrostatic Actuation

    KAUST Repository

    Saghir, Shahid

    2016-01-01

    The first objective of the dissertation is to develop a suitable reduced order model capable of investigating the nonlinear mechanical behavior of von-Karman plates under electrostatic actuation. The second objective is to investigate the nonlinear

  13. Control of a perturbed under-actuated mechanical system

    KAUST Repository

    Zayane, Chadia; Laleg-Kirati, Taous-Meriem; Chemori, Ahmed

    2015-01-01

    In this work, the trajectory tracking problem for an under-actuated mechanical system in presence of unknown input disturbances is addressed. The studied inertia wheel inverted pendulum falls in the class of non minimum phase systems. The proposed

  14. Active joint mechanism driven by multiple actuators made of flexible bags: a proposal of dual structural actuator.

    Science.gov (United States)

    Kimura, Hitoshi; Matsuzaki, Takuya; Kataoka, Mokutaro; Inou, Norio

    2013-01-01

    An actuator is required to change its speed and force depending on the situation. Using multiple actuators for one driving axis is one of the possible solutions; however, there is an associated problem of output power matching. This study proposes a new active joint mechanism using multiple actuators. Because the actuator is made of a flexible bag, it does not interfere with other actuators when it is depressurized. The proposed joint achieved coordinated motion of multiple actuators. This report also discusses a new actuator which has dual cylindrical structure. The cylinders are composed of flexible bags with different diameters. The joint torque is estimated based on the following factors: empirical formula for the flexible actuator torque, geometric relationship between the joint and the actuator, and the principle of virtual work. The prototype joint mechanism achieves coordinated motion of multiple actuators for one axis. With this motion, small inner actuator contributes high speed motion, whereas large outer actuator generates high torque. The performance of the prototype joint is examined by speed and torque measurements. The joint showed about 30% efficiency at 2.0 Nm load torque under 0.15 MPa air input.

  15. Active-passive hybrid piezoelectric actuators for high-precision hard disk drive servo systems

    Science.gov (United States)

    Chan, Kwong Wah; Liao, Wei-Hsin

    2006-03-01

    Positioning precision is crucial to today's increasingly high-speed, high-capacity, high data density, and miniaturized hard disk drives (HDDs). The demand for higher bandwidth servo systems that can quickly and precisely position the read/write head on a high track density becomes more pressing. Recently, the idea of applying dual-stage actuators to track servo systems has been studied. The push-pull piezoelectric actuated devices have been developed as micro actuators for fine and fast positioning, while the voice coil motor functions as a large but coarse seeking. However, the current dual-stage actuator design uses piezoelectric patches only without passive damping. In this paper, we propose a dual-stage servo system using enhanced active-passive hybrid piezoelectric actuators. The proposed actuators will improve the existing dual-stage actuators for higher precision and shock resistance, due to the incorporation of passive damping in the design. We aim to develop this hybrid servo system not only to increase speed of track seeking but also to improve precision of track following servos in HDDs. New piezoelectrically actuated suspensions with passive damping have been designed and fabricated. In order to evaluate positioning and track following performances for the dual-stage track servo systems, experimental efforts are carried out to implement the synthesized active-passive suspension structure with enhanced piezoelectric actuators using a composite nonlinear feedback controller.

  16. Sealing-free fast-response paraffin/nanoporous gold hybrid actuator

    Science.gov (United States)

    Ye, Xing-Long; Jin, Hai-Jun

    2017-09-01

    Paraffin-based actuators can deliver large actuation strokes and high actuation stress, but often suffer from a low response rate and leaking problems. Here, we report a new paraffin/metal hybrid actuator, which was fabricated by infiltrating nanoporous gold with paraffin. It exhibits a fast actuation rate owing to the high thermal conductivity of the inter-connected metal phase, and requires no external sealing because liquid paraffin can be well confined in nanoscale channels, due to the large capillarity. We found that in this hybrid actuator, the stress generated by actuation is negligibly small when the characteristic size of the nanoporous gold (L) is above ˜70 nm, and increases dramatically with a decreasing size when L paraffin wax—the paraffin in smaller pores can sustain larger tensile stress, and thus the contraction of paraffin during cooling can be translated into larger compression stress and strain energy in a metal framework, leading to a larger actuation stress and energy. We also demonstrate that complex actuation motions can be achieved by incorporating hierarchical-structured nanoporous metal with paraffin.

  17. Implementation of heaters on thermally actuated spacecraft mechanisms

    Science.gov (United States)

    Busch, John D.; Bokaie, Michael D.

    1994-01-01

    This paper presents general insight into the design and implementation of heaters as used in actuating mechanisms for spacecraft. Problems and considerations that were encountered during development of the Deep Space Probe and Science Experiment (DSPSE) solar array release mechanism are discussed. Obstacles included large expected fluctuations in ambient temperature, variations in voltage supply levels outgassing concerns, heater circuit design, materials selection, and power control options. Successful resolution of these issues helped to establish a methodology which can be applied to many of the heater design challenges found in thermally actuated mechanisms.

  18. Floating electrode microelectromechanical system capacitive switches: A different actuation mechanism

    Science.gov (United States)

    Papaioannou, G.; Giacomozzi, F.; Papandreou, E.; Margesin, B.

    2011-08-01

    The paper investigates the actuation mechanism in floating electrode microelectromechanical system capacitive switches. It is demonstrated that in the pull-in state, the device operation turns from voltage to current controlled actuation. The current arises from Poole-Frenkel mechanism in the dielectric film and Fowler-Nordheim in the bridge-floating electrode air gap. The pull-out voltage seems to arise from the abrupt decrease of Fowler-Nordheim electric field intensity. This mechanism seems to be responsible for the very small difference with respect to the pull-in voltage.

  19. H∞ control of piezo actuated tilting mirror mechanism

    NARCIS (Netherlands)

    Van Dijk, J.

    2015-01-01

    In here the high bandwidth (2000 Hz.) feedback control of a precision mechanisms driven by a piezo actuator demanding a high absolute accuracy is discussed. The mechanism considered is rotating a mirror for laser bundle manipulation. It will be shown that a loopshaping controller design using the

  20. Adaptive mechanical-wetting lens actuated by ferrofluids

    Science.gov (United States)

    Cheng, Hui-Chuan; Xu, Su; Liu, Yifan; Levi, Shoshana; Wu, Shin-Tson

    2011-04-01

    We report an adaptive mechanical-wetting lens actuated by ferrofluids. The ferrofluids works like a piston to pump liquids in and out from the lens chamber, which in turn reshapes the lens curvature and changes the focal length. Both positive and negative lenses are demonstrated experimentally. The ferrofluid-actuated mechanical-wetting lens exhibits some attractive features, such as high resolution, fast response time, low power consumption, simple structure and electronic control, weak gravity effect, and low cost. Its potential applications in medical imaging, surveillance, and commercial electronics are foreseeable.

  1. Spacecraft Hybrid (Mixed-Actuator) Attitude Control Experiences on NASA Science Missions

    Science.gov (United States)

    Dennehy, Cornelius J.

    2014-01-01

    There is a heightened interest within NASA for the design, development, and flight implementation of mixed-actuator hybrid attitude control systems for science spacecraft that have less than three functional reaction wheel actuators. This interest is driven by a number of recent reaction wheel failures on aging, but what could be still scientifically productive, NASA spacecraft if a successful hybrid attitude control mode can be implemented. Over the years, hybrid (mixed-actuator) control has been employed for contingency attitude control purposes on several NASA science mission spacecraft. This paper provides a historical perspective of NASA's previous engineering work on spacecraft mixed-actuator hybrid control approaches. An update of the current situation will also be provided emphasizing why NASA is now so interested in hybrid control. The results of the NASA Spacecraft Hybrid Attitude Control Workshop, held in April of 2013, will be highlighted. In particular, the lessons learned captured from that workshop will be shared in this paper. An update on the most recent experiences with hybrid control on the Kepler spacecraft will also be provided. This paper will close with some future considerations for hybrid spacecraft control.

  2. Ionic and viscoelastic mechanisms of a bucky-gel actuator

    Science.gov (United States)

    Kruusamäe, Karl; Sugino, Takushi; Asaka, Kinji

    2015-07-01

    Ionic electromechanically active polymers (IEAPs) are considered attractive candidates for soft, miniature, and lightweight actuators. The bucky-gel actuator is a carbonaceous subtype of IEAP that due to its structure (i.e. two highly porous electrodes sandwiching a thin ion-permeable electrolyte layer) and composition (i.e. being composed of soft porous polymer, carbon nanotubes, and ionic liquid) is very similar to an electric double-layer capacitor. In response to the voltage applied between the electrodes of a bucky-gel actuator, the laminar structure bends. The time domain behavior exhibits, however, a phenomenon called the back-relaxation, i.e., after some time the direction of bending is reversed even though voltage remains constant. In spite of the working mechanism of IEAP actuators being generally attributed to the transport of ions within the soft multilayer system, the specific details remain unclear. A so-called two-carrier model proposes that the bending and subsequent back-relaxation are caused by the relocation of two ionic species having different mobilities as they enter and exit the electrode layers. By adopting the two-carrier model for bucky-gel actuators, we see very good agreement between the mathematical representation and the experimental data of the electromechanical behavior. Furthermore, since the bucky-gel actuator is viscoelastic, we propose to use the time domain response of a blocking force as the key parameter related to the inner ionic mechanism. We also introduce a method to estimate the viscoelastic creep compliance function from the time domain responses for curvature and blocking force. This analysis includes four types of bucky-gel actuators of varying composition and structure.

  3. Mechanical design of a shape memory alloy actuated prosthetic hand.

    Science.gov (United States)

    De Laurentis, Kathryn J; Mavroidis, Constantinos

    2002-01-01

    This paper presents the mechanical design for a new five fingered, twenty degree-of-freedom dexterous hand patterned after human anatomy and actuated by Shape Memory Alloy artificial muscles. Two experimental prototypes of a finger, one fabricated by traditional means and another fabricated by rapid prototyping techniques, are described and used to evaluate the design. An important aspect of the Rapid Prototype technique used here is that this multi-articulated hand will be fabricated in one step, without requiring assembly, while maintaining its desired mobility. The use of Shape Memory Alloy actuators combined with the rapid fabrication of the non-assembly type hand, reduce considerably its weight and fabrication time. Therefore, the focus of this paper is the mechanical design of a dexterous hand that combines Rapid Prototype techniques and smart actuators. The type of robotic hand described in this paper can be utilized for applications requiring low weight, compactness, and dexterity such as prosthetic devices, space and planetary exploration.

  4. Shape memory-based actuators and release mechanisms therefrom

    Science.gov (United States)

    Vaidyanathan, Rajan (Inventor); Snyder, Daniel W. (Inventor); Schoenwald, David K. (Inventor); Lam, Nhin S. (Inventor); Watson, Daniel S. (Inventor); Krishnan, Vinu B. (Inventor); Noebe, Ronald D. (Inventor)

    2012-01-01

    SM-based actuators (110) and release mechanisms (100) therefrom and systems (500) including one or more release mechanisms (100). The actuators (110) comprise a SM member (118) and a deformable member (140) mechanically coupled to the SM member (118) which deforms upon a shape change of the SM member triggered by a phase transition of the SM member. A retaining element (160) is mechanically coupled to the deformable member (140), wherein the retaining element (160) moves upon the shape change. Release mechanism (100) include an actuator, a rotatable mechanism (120) including at least one restraining feature (178) for restraining rotational movement of the retaining element (160) before the shape change, and at least one spring (315) that provides at least one locked spring-loaded position when the retaining element is in the restraining feature and at least one released position that is reached when the retaining element is in a position beyond the restraining feature (178). The rotatable mechanism (120) includes at least one load-bearing protrusion (310). A hitch (400) is for mechanically coupling to the load, wherein the hitch is supported on the load bearing protrusion (310) when the rotatable mechanism is in the locked spring-loaded position.

  5. Tunable Mechanical Metamaterials through Hybrid Kirigami Structures.

    Science.gov (United States)

    Hwang, Doh-Gyu; Bartlett, Michael D

    2018-02-21

    Inspired by the art of paper cutting, kirigami provides intriguing tools to create materials with unconventional mechanical and morphological responses. This behavior is appealing in multiple applications such as stretchable electronics and soft robotics and presents a tractable platform to study structure-property relationships in material systems. However, mechanical response is typically controlled through a single or fractal cut type patterned across an entire kirigami sheet, limiting deformation modes and tunability. Here we show how hybrid patterns of major and minor cuts creates new opportunities to introduce boundary conditions and non-prismatic beams to enable highly tunable mechanical responses. This hybrid approach reduces stiffness by a factor of ~30 while increasing ultimate strain by a factor of 2 (up to 750% strain) relative to single incision patterns. We present analytical models and generate general design criteria that is in excellent agreement with experimental data from nanoscopic to macroscopic systems. These hybrid kirigami materials create new opportunities for multifunctional materials and structures, which we demonstrate with stretchable kirigami conductors with nearly constant electrical resistance up to >400% strain and magnetoactive actuators with extremely rapid response (>10,000% strain s -1 ) and high, repeatable elongation (>300% strain).

  6. Design and property analysis of a hybrid linear actuator based on shape memory alloy

    International Nuclear Information System (INIS)

    Zhang, Xiaoguang; Hu, Jinhong; Mao, Shixin; Dong, Erbao; Yang, Jie

    2014-01-01

    This paper introduces two methods for solving two bottlelike problems regarding the shape memory alloy (SMA) application as actuators. These methods are ‘rotating output,’ which aims to solve the problem of the low working frequency caused by the demand for cool time, and ‘accumulated shifting,’ which solves the problem of difficult-to-obtain output displacements in a large scale. We also introduce a hybrid linear actuator that applies the two methods and achieves both a strong force and an accurate large output displacement while working at a high frequency based on the SMA wires and DC motors. A prototype of this actuator was fabricated and tested to verify the two methods. This hybrid actuator system dynamic model, which was composed of the constitutive model of the SMA, the electrical and heat transfer behavior of the SMA wires and the dynamics of the linear actuation system, was established and discussed. Our study aims to illuminate the application of an SMA in actuators with the proposed methods with regard to its two main problems. An actuator with a high power-weight ratio and the capability to work at a high frequency, as well as accurate linear step displacements in a large scale, is also presented. (paper)

  7. Analysis of actuator delay and its effect on uncertainty quantification for real-time hybrid simulation

    Science.gov (United States)

    Chen, Cheng; Xu, Weijie; Guo, Tong; Chen, Kai

    2017-10-01

    Uncertainties in structure properties can result in different responses in hybrid simulations. Quantification of the effect of these uncertainties would enable researchers to estimate the variances of structural responses observed from experiments. This poses challenges for real-time hybrid simulation (RTHS) due to the existence of actuator delay. Polynomial chaos expansion (PCE) projects the model outputs on a basis of orthogonal stochastic polynomials to account for influences of model uncertainties. In this paper, PCE is utilized to evaluate effect of actuator delay on the maximum displacement from real-time hybrid simulation of a single degree of freedom (SDOF) structure when accounting for uncertainties in structural properties. The PCE is first applied for RTHS without delay to determine the order of PCE, the number of sample points as well as the method for coefficients calculation. The PCE is then applied to RTHS with actuator delay. The mean, variance and Sobol indices are compared and discussed to evaluate the effects of actuator delay on uncertainty quantification for RTHS. Results show that the mean and the variance of the maximum displacement increase linearly and exponentially with respect to actuator delay, respectively. Sensitivity analysis through Sobol indices also indicates the influence of the single random variable decreases while the coupling effect increases with the increase of actuator delay.

  8. Stroke maximizing and high efficient hysteresis hybrid modeling for a rhombic piezoelectric actuator

    Science.gov (United States)

    Shao, Shubao; Xu, Minglong; Zhang, Shuwen; Xie, Shilin

    2016-06-01

    Rhombic piezoelectric actuator (RPA), which employs a rhombic mechanism to amplify the small stroke of PZT stack, has been widely used in many micro-positioning machineries due to its remarkable properties such as high displacement resolution and compact structure. In order to achieve large actuation range along with high accuracy, the stroke maximizing and compensation for the hysteresis are two concerns in the use of RPA. However, existing maximization methods based on theoretical model can hardly accurately predict the maximum stroke of RPA because of approximation errors that are caused by the simplifications that must be made in the analysis. Moreover, despite the high hysteresis modeling accuracy of Preisach model, its modeling procedure is trivial and time-consuming since a large set of experimental data is required to determine the model parameters. In our research, to improve the accuracy of theoretical model of RPA, the approximation theory is employed in which the approximation errors can be compensated by two dimensionless coefficients. To simplify the hysteresis modeling procedure, a hybrid modeling method is proposed in which the parameters of Preisach model can be identified from only a small set of experimental data by using the combination of discrete Preisach model (DPM) with particle swarm optimization (PSO) algorithm. The proposed novel hybrid modeling method can not only model the hysteresis with considerable accuracy but also significantly simplified the modeling procedure. Finally, the inversion of hysteresis is introduced to compensate for the hysteresis non-linearity of RPA, and consequently a pseudo-linear system can be obtained.

  9. Mechanical behavior analysis on electrostatically actuated rectangular microplates

    Science.gov (United States)

    Li, Zhikang; Zhao, Libo; Jiang, Zhuangde; Ye, Zhiying; Dai, Lu; Zhao, Yulong

    2015-03-01

    Microplates are widely used in various MEMS devices based on electrostatic actuation such as MEMS switches, micro pumps and capacitive micromachined ultrasonic transducers (CMUTs). Accurate predictions for the mechanical behavior of the microplate under electrostatic force are important not only for the design and optimization of these electrostatic devices but also for their operation. This paper presents a novel reduced-order model for electrostatically actuated rectangular and square microplates with a new method to treat the nonlinear electrostatic force. The model was developed using Galerkin method which turned the partial-differential equation governing the microplates into an ordinary equation system. Using this model and cosine-like deflection functions, explicit expressions were established for the deflection and pull-in voltage of the rectangular and square microplates. The theoretical results were well validated with the finite element method simulations and experimental data of literature. The expressions for the deflection analysis are able to predict the deflection up to the pull-in position with an error less than 5.0%. The expressions for the pull-in voltage analysis can determine the pull-in voltages with errors less than 1.0%. Additionally, the method to calculate the capacitance variation of the electrostatically actuated microplates was proposed. These theoretical analyses are helpful for design and optimization of electrostatically actuated microdevices.

  10. Mechanical behavior analysis on electrostatically actuated rectangular microplates

    International Nuclear Information System (INIS)

    Li, Zhikang; Zhao, Libo; Jiang, Zhuangde; Ye, Zhiying; Zhao, Yulong; Dai, Lu

    2015-01-01

    Microplates are widely used in various MEMS devices based on electrostatic actuation such as MEMS switches, micro pumps and capacitive micromachined ultrasonic transducers (CMUTs). Accurate predictions for the mechanical behavior of the microplate under electrostatic force are important not only for the design and optimization of these electrostatic devices but also for their operation. This paper presents a novel reduced-order model for electrostatically actuated rectangular and square microplates with a new method to treat the nonlinear electrostatic force. The model was developed using Galerkin method which turned the partial-differential equation governing the microplates into an ordinary equation system. Using this model and cosine-like deflection functions, explicit expressions were established for the deflection and pull-in voltage of the rectangular and square microplates. The theoretical results were well validated with the finite element method simulations and experimental data of literature. The expressions for the deflection analysis are able to predict the deflection up to the pull-in position with an error less than 5.0%. The expressions for the pull-in voltage analysis can determine the pull-in voltages with errors less than 1.0%. Additionally, the method to calculate the capacitance variation of the electrostatically actuated microplates was proposed. These theoretical analyses are helpful for design and optimization of electrostatically actuated microdevices. (paper)

  11. Control of a perturbed under-actuated mechanical system

    KAUST Repository

    Zayane, Chadia

    2015-11-05

    In this work, the trajectory tracking problem for an under-actuated mechanical system in presence of unknown input disturbances is addressed. The studied inertia wheel inverted pendulum falls in the class of non minimum phase systems. The proposed high order sliding mode control architecture including a controller and differentiator allows to track accurately the predefined trajectory and to stabilize the internal dynamics. The robustness of the proposed approach is illustrated through different perturbation and output noise configurations.

  12. An optimal control strategy for hybrid actuator systems: Application to an artificial muscle with electric motor assist.

    Science.gov (United States)

    Ishihara, Koji; Morimoto, Jun

    2018-03-01

    Humans use multiple muscles to generate such joint movements as an elbow motion. With multiple lightweight and compliant actuators, joint movements can also be efficiently generated. Similarly, robots can use multiple actuators to efficiently generate a one degree of freedom movement. For this movement, the desired joint torque must be properly distributed to each actuator. One approach to cope with this torque distribution problem is an optimal control method. However, solving the optimal control problem at each control time step has not been deemed a practical approach due to its large computational burden. In this paper, we propose a computationally efficient method to derive an optimal control strategy for a hybrid actuation system composed of multiple actuators, where each actuator has different dynamical properties. We investigated a singularly perturbed system of the hybrid actuator model that subdivided the original large-scale control problem into smaller subproblems so that the optimal control outputs for each actuator can be derived at each control time step and applied our proposed method to our pneumatic-electric hybrid actuator system. Our method derived a torque distribution strategy for the hybrid actuator by dealing with the difficulty of solving real-time optimal control problems. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  13. Modeling of MEMS Mirrors Actuated by Phase-Change Mechanism

    Directory of Open Access Journals (Sweden)

    David Torres

    2017-04-01

    Full Text Available Given the multiple applications for micro-electro-mechanical system (MEMS mirror devices, most of the research efforts are focused on improving device performance in terms of tilting angles, speed, and their integration into larger arrays or systems. The modeling of these devices is crucial for enabling a platform, in particular, by allowing for the future control of such devices. In this paper, we present the modeling of a MEMS mirror structure with four actuators driven by the phase-change of a thin film. The complexity of the device structure and the nonlinear behavior of the actuation mechanism allow for a comprehensive study that encompasses simpler electrothermal designs, thus presenting a general approach that can be adapted to most MEMS mirror designs based on this operation principle. The MEMS mirrors presented in this work are actuated by Joule heating and tested using optical techniques. Mechanical and thermal models including both pitch and roll displacements are developed by combining theoretical analysis (using both numerical and analytical tools with experimental data and subsequently verifying with quasi-static and dynamic experiments.

  14. Electroactive Polymer (EAP) Actuation of Mechanisms and Robotic Devices

    Science.gov (United States)

    Bar-Cohen, Y.; Leary, S.; Harrison, J.; Smith, J.

    1999-01-01

    Actuators are responsible to the operative capability of manipulation systems and robots. In recent years, electroactive polymers (EAP) have emerged as potential alternative to conventional actuators.

  15. Teleoperation System with Hybrid Pneumatic-Piezoelectric Actuation for MRI-Guided Needle Insertion with Haptic Feedback.

    Science.gov (United States)

    Shang, Weijian; Su, Hao; Li, Gang; Fischer, Gregory S

    2013-01-01

    This paper presents a surgical master-slave tele-operation system for percutaneous interventional procedures under continuous magnetic resonance imaging (MRI) guidance. This system consists of a piezoelectrically actuated slave robot for needle placement with integrated fiber optic force sensor utilizing Fabry-Perot interferometry (FPI) sensing principle. The sensor flexure is optimized and embedded to the slave robot for measuring needle insertion force. A novel, compact opto-mechanical FPI sensor interface is integrated into an MRI robot control system. By leveraging the complementary features of pneumatic and piezoelectric actuation, a pneumatically actuated haptic master robot is also developed to render force associated with needle placement interventions to the clinician. An aluminum load cell is implemented and calibrated to close the impedance control loop of the master robot. A force-position control algorithm is developed to control the hybrid actuated system. Teleoperated needle insertion is demonstrated under live MR imaging, where the slave robot resides in the scanner bore and the user manipulates the master beside the patient outside the bore. Force and position tracking results of the master-slave robot are demonstrated to validate the tracking performance of the integrated system. It has a position tracking error of 0.318mm and sine wave force tracking error of 2.227N.

  16. Teleoperation System with Hybrid Pneumatic-Piezoelectric Actuation for MRI-Guided Needle Insertion with Haptic Feedback

    Science.gov (United States)

    Shang, Weijian; Su, Hao; Li, Gang; Fischer, Gregory S.

    2014-01-01

    This paper presents a surgical master-slave tele-operation system for percutaneous interventional procedures under continuous magnetic resonance imaging (MRI) guidance. This system consists of a piezoelectrically actuated slave robot for needle placement with integrated fiber optic force sensor utilizing Fabry-Perot interferometry (FPI) sensing principle. The sensor flexure is optimized and embedded to the slave robot for measuring needle insertion force. A novel, compact opto-mechanical FPI sensor interface is integrated into an MRI robot control system. By leveraging the complementary features of pneumatic and piezoelectric actuation, a pneumatically actuated haptic master robot is also developed to render force associated with needle placement interventions to the clinician. An aluminum load cell is implemented and calibrated to close the impedance control loop of the master robot. A force-position control algorithm is developed to control the hybrid actuated system. Teleoperated needle insertion is demonstrated under live MR imaging, where the slave robot resides in the scanner bore and the user manipulates the master beside the patient outside the bore. Force and position tracking results of the master-slave robot are demonstrated to validate the tracking performance of the integrated system. It has a position tracking error of 0.318mm and sine wave force tracking error of 2.227N. PMID:25126446

  17. Mechanical Design of Innovative Electromagnetic Linear Actuators for Marine Applications

    Science.gov (United States)

    Muscia, Roberto

    2017-11-01

    We describe an engineering solution to manufacture electromagnetic linear actuators for moving rudders and fin stabilizers of military shipsItalian Ministry of Defence, General Direction of Naval Equipments (NAVARM), Projects ISO (2012-2014) and EDDA (2015-2017). . The solution defines the transition from the conceptual design of the device initially studied from an electromagnetic point of view to mechanical configurations that really work. The structural problems that have been resolved with the proposed configuration are described. In order to validate the design choices discussed we illustrate some results of the numerical simulations performed by the structural finite elements method. These results quantitatively justify the suggested mechanical solution by evaluating stresses and deformations in a virtual prototype of the structure during its functioning. The parts of the device that have been studied are the most critical because in cases of excessive deformation/stress, they can irreparably compromise the actuator operation. These parts are the pole piece-base set and the retention cages of the permanent magnets. The FEM analysis has allowed us to identify the most stressed areas of the previous elements whose shape has been appropriately designed so as to reduce the maximum stresses and deformations. Moreover, the FEM analysis helped to find the most convenient solution to join the pole pieces to the respective bases. The good results obtained by the suggested engineering solution have been experimentally confirmed by tests on a small prototype actuator purposely manufactured. Finally, a qualitative analysis of the engineering problems that have to be considered to design electromagnetic linear actuators bigger than the one already manufactured is illustrated.

  18. Mechanical Design of Innovative Electromagnetic Linear Actuators for Marine Applications

    Directory of Open Access Journals (Sweden)

    Muscia Roberto

    2017-11-01

    Full Text Available We describe an engineering solution to manufacture electromagnetic linear actuators for moving rudders and fin stabilizers of military shipsItalian Ministry of Defence, General Direction of Naval Equipments (NAVARM, Projects ISO (2012-2014 and EDDA (2015-2017.. The solution defines the transition from the conceptual design of the device initially studied from an electromagnetic point of view to mechanical configurations that really work. The structural problems that have been resolved with the proposed configuration are described. In order to validate the design choices discussed we illustrate some results of the numerical simulations performed by the structural finite elements method. These results quantitatively justify the suggested mechanical solution by evaluating stresses and deformations in a virtual prototype of the structure during its functioning. The parts of the device that have been studied are the most critical because in cases of excessive deformation/stress, they can irreparably compromise the actuator operation. These parts are the pole piece-base set and the retention cages of the permanent magnets. The FEM analysis has allowed us to identify the most stressed areas of the previous elements whose shape has been appropriately designed so as to reduce the maximum stresses and deformations. Moreover, the FEM analysis helped to find the most convenient solution to join the pole pieces to the respective bases. The good results obtained by the suggested engineering solution have been experimentally confirmed by tests on a small prototype actuator purposely manufactured. Finally, a qualitative analysis of the engineering problems that have to be considered to design electromagnetic linear actuators bigger than the one already manufactured is illustrated.

  19. Development of a hybrid bearing using permanent magnets and piezoelectric actuators

    International Nuclear Information System (INIS)

    Park, Jung-Ho; Ham, Young-Bog; Yun, So-Nam; Lee, Hu-Seung

    2010-01-01

    In this study, a hybrid magnetic bearing with permanent magnets and piezoelectric actuators is investigated. First, in this study, a novel concept in which piezoelectric actuators are used to compensate for low stiffness and damping resulting from the unstable characteristics of a passive magnetic bearing using only permanent magnets is proposed. Secondly, the permanent magnets are optimally arranged through an electromagnetic field analysis. Then, the driving amplifier unit and a prototype radial bearing using the proposed concept are fabricated. Finally, basic characteristics, such as the results of an impact test and a rotational runout test with constant speed are investigated and discussed, and experiments using PID control method are conducted.

  20. Helmholtz resonance in a piezoelectric–hydraulic pump-based hybrid actuator

    International Nuclear Information System (INIS)

    Kim, Gi-Woo; Wang, K W

    2011-01-01

    This paper demonstrates that a hydraulically acting Helmholtz resonator can exist in a piezoelectric–hydraulic pump (PHP) based hybrid actuator, which in turn affects the volumetric efficiency of the PHP. The simulation and experimental results illustrate the effect of Helmholtz resonance on the flow rate performance of the PHP. The study also shows how to shift the Helmholtz resonant frequency to a higher value through changing parameters such as the cylinder diameter and the effective bulk modulus of the working fluid, which will improve the volumetric efficiency and broaden the operating frequency range of the PHP actuator

  1. Hybrid Micro-Electro-Mechanical Tunable Filter

    Science.gov (United States)

    2007-09-01

    and polymer hybrid actuator and applications as a tunable filter in telecom and in IR chemical detector,” in Micromachining and Microfabrication...consistently achieved. At this temperature, SU8 - SU-8 bonding withstood subsequent processing steps, resulting in a 57% bond yield and an overall 30

  2. Actuation mechanisms of carbon nanotube-based architectures

    Science.gov (United States)

    Geier, Sebastian; Mahrholz, Thorsten; Wierach, Peter; Sinapius, Michael

    2016-04-01

    State of the art smart materials such as piezo ceramics or electroactive polymers cannot feature both, mechanical stiffness and high active strain. Moreover, properties like low density, high mechanical stiffness and high strain at the same time driven by low energy play an increasingly important role for their future application. Carbon nanotubes (CNT), show this behavior. Their active behavior was observed 1999 the first time using paper-like mats made of CNT. Therefore the CNT-papers are electrical charged within an electrolyte thus forming a double- layer. The measured deflection of CNT material is based on the interaction between the charged high surface area formed by carbon nanotubes and ions provided by the electrolyte. Although CNT-papers have been extensively analyzed as well at the macro-scale as nano-scale there is still no generally accepted theory for the actuation mechanism. This paper focuses on investigations of the actuation mechanisms of CNT-papers in comparison to vertically aligned CNT-arrays. One reason of divergent results found in literature might be attributed to different types of CNT samples. While CNT-papers represent architectures of short CNTs which need to bridge each other to form the dimensions of the sample, the continuous CNTs of the array feature a length of almost 3 mm, along which the experiments are carried out. Both sample types are tested within an actuated tensile test set-up under different conditions. While the CNT-papers are tested in water-based electrolytes with comparably small redox-windows the hydrophobic CNT-arrays are tested in ionic liquids with comparatively larger redox-ranges. Furthermore an in-situ micro tensile test within an SEM is carried out to prove the optimized orientation of the MWCNTs as result of external load. It was found that the performance of CNT-papers strongly depends on the test conditions. However, the CNT-arrays are almost unaffected by the conditions showing active response at negative

  3. NASA Workshop on Hybrid (Mixed-Actuator) Spacecraft Attitude Control

    Science.gov (United States)

    Dennehy, Cornelius J.; Kunz, Nans

    2014-01-01

    At the request of the Science Mission Directorate Chief Engineer, the NASA Technical Fellow for Guidance, Navigation & Control assembled and facilitated a workshop on Spacecraft Hybrid Attitude Control. This multi-Center, academic, and industry workshop, sponsored by the NASA Engineering and Safety Center (NESC), was held in April 2013 to unite nationwide experts to present and discuss the various innovative solutions, techniques, and lessons learned regarding the development and implementation of the various hybrid attitude control system solutions investigated or implemented. This report attempts to document these key lessons learned with the 16 findings and 9 NESC recommendations.

  4. Dynamic Characteristics of a Hydraulic Amplification Mechanism for Large Displacement Actuators Systems

    Directory of Open Access Journals (Sweden)

    Xavier Arouette

    2010-03-01

    Full Text Available We have developed a hydraulic displacement amplification mechanism (HDAM and studied its dynamic response when combined with a piezoelectric actuator. The HDAM consists of an incompressible fluid sealed in a microcavity by two largely deformable polydimethylsiloxane (PDMS membranes. The geometry with input and output surfaces having different cross-sectional areas creates amplification. By combining the HDAM with micro-actuators, we can amplify the input displacement generated by the actuators, which is useful for applications requiring large deformation, such as tactile displays. We achieved a mechanism offering up to 18-fold displacement amplification for static actuation and 12-fold for 55 Hz dynamic actuation.

  5. A portable air jet actuator device for mechanical system identification

    Science.gov (United States)

    Belden, Jesse; Staats, Wayne L.; Mazumdar, Anirban; Hunter, Ian W.

    2011-03-01

    System identification of limb mechanics can help diagnose ailments and can aid in the optimization of robotic limb control parameters and designs. An interesting fluid phenomenon—the Coandă effect—is utilized in a portable actuator to provide a stochastic binary force disturbance to a limb system. The design of the actuator is approached with the goal of creating a portable device which could be deployed on human or robotic limbs for in situ mechanical system identification. The viability of the device is demonstrated by identifying the parameters of an underdamped elastic beam system with fixed inertia and stiffness and variable damping. The nonparametric compliance impulse response yielded from the system identification is modeled as a second-order system and the resultant parameters are found to be in excellent agreement with those found using more traditional system identification techniques. The current design could be further miniaturized and developed as a portable, wireless, unrestrained mechanical system identification instrument for less intrusive and more widespread use.

  6. Optimization of mechanical performance of oxidative nano-particle electrode nitrile butadiene rubber conducting polymer actuator.

    Science.gov (United States)

    Kim, Baek-Chul; Park, S J; Cho, M S; Lee, Y; Nam, J D; Choi, H R; Koo, J C

    2009-12-01

    Present work delivers a systematical evaluation of actuation efficiency of a nano-particle electrode conducting polymer actuator fabricated based on Nitrile Butadiene Rubber (NBR). Attempts are made for maximizing mechanical functionality of the nano-particle electrode conducting polymer actuator that can be driven in the air. As the conducting polymer polypyrrole of the actuator is to be fabricated through a chemical oxidation polymerization process that may impose certain limitations on both electrical and mechanical functionality of the actuator, a coordinated study for optimization process of the actuator is necessary for maximizing its performance. In this article actuation behaviors of the nano-particle electrode polypyrrole conducting polymer is studied and an optimization process for the mechanical performance maximization is performed.

  7. Thermo-Electro-Mechanical Analysis of a Curved Functionally Graded Piezoelectric Actuator with Sandwich Structure

    Directory of Open Access Journals (Sweden)

    Liying Jiang

    2011-12-01

    Full Text Available In this work, the problem of a curved functionally graded piezoelectric (FGP actuator with sandwich structure under electrical and thermal loads is investigated. The middle layer in the sandwich structure is functionally graded with the piezoelectric coefficient g31 varying continuously along the radial direction of the curved actuator. Based on the theory of linear piezoelectricity, analytical solutions are obtained by using Airy stress function to examine the effects of material gradient and heat conduction on the performance of the curved actuator. It is found that the material gradient and thermal load have significant influence on the electroelastic fields and the mechanical response of the curved FGP actuator. Without the sacrifice of actuation deflection, smaller internal stresses are generated by using the sandwich actuator with functionally graded piezoelectric layer instead of the conventional bimorph actuator. This work is very helpful for the design and application of curved piezoelectric actuators under thermal environment.

  8. Thermo-Electro-Mechanical Analysis of a Curved Functionally Graded Piezoelectric Actuator with Sandwich Structure.

    Science.gov (United States)

    Yan, Zhi; Zaman, Mostafa; Jiang, Liying

    2011-12-12

    In this work, the problem of a curved functionally graded piezoelectric (FGP) actuator with sandwich structure under electrical and thermal loads is investigated. The middle layer in the sandwich structure is functionally graded with the piezoelectric coefficient g 31 varying continuously along the radial direction of the curved actuator. Based on the theory of linear piezoelectricity, analytical solutions are obtained by using Airy stress function to examine the effects of material gradient and heat conduction on the performance of the curved actuator. It is found that the material gradient and thermal load have significant influence on the electroelastic fields and the mechanical response of the curved FGP actuator. Without the sacrifice of actuation deflection, smaller internal stresses are generated by using the sandwich actuator with functionally graded piezoelectric layer instead of the conventional bimorph actuator. This work is very helpful for the design and application of curved piezoelectric actuators under thermal environment.

  9. Advanced sensor fault detection and isolation for electro-mechanical flight actuators

    OpenAIRE

    Ossmann, Daniel; van der Linden, Franciscus

    2015-01-01

    Moving towards the more electric aircraft to be able to replace mechanic, hydraulic and pneumatic components of an aircraft, the aircraft industry calls for new technologies able to support this trend. One of these technologies is the development of advanced electro-mechanical actuators for aircraft control surfaces. Step by step hydraulic actuators are replaced by their electro-mechanical alternatives featuring weight and cost savings. As hydraulic actuators are used for decades by the air...

  10. Hybrid microcircuit metallization system for the SLL micro actuator

    International Nuclear Information System (INIS)

    Hampy, R.E.; Knauss, G.L.; Komarek, E.E.; Kramer, D.K.; Villaueva, J.

    1976-03-01

    A thin film technique developed for the SLL Micro Actuator in which both gold and aluminum can be incorporated on sapphire or fine grained alumina substrates in a two-level metallization system is described. Tungsten is used as a lateral transition metal permitting electrical contact between the gold and aluminum without the two metals coming in physical contact. Silicon dioxide serves as an insulator between the tungsten and aluminum for crossover purposes, and vias through the silicon dioxide permit interconnections where desired. Tungsten-gold is the first level conductor except at crossovers where tungsten only is used and aluminum is the second level conductor. Sheet resistances of the two levels can be as low as 0.01 ohm/square. Line widths and spaces as small as 0.025 mm can be attained. A second layer of silicon dioxide is deposited over the metallization and opened for all gold and aluminum bonding areas. The metallization system permits effective interconnection of a mixture of devices having both gold and aluminum terminations without creating undesirable gold-aluminum interfaces. Processing temperatures up to 400 0 C can be tolerated for short times without effect on bondability, conductor, and insulator characteristics, thus permitting silicon-gold eutectic die attachment, component soldering, and higher temperatures during gold lead bonding. Tests conducted on special test pattern circuits indicate good stability over the temperature range -55 to +150 0 C. Aging studies indicate no degradation in characteristics in tests of 500 h duration at 150 0 C

  11. Designing and testing lightweight shoulder prostheses with hybrid actuators for movements involved in typical activities of daily living and impact absorption

    Directory of Open Access Journals (Sweden)

    Sekine M

    2015-07-01

    Full Text Available Masashi Sekine,1,2 Kahori Kita,1 Wenwei Yu1 1Center for Frontier Medical Engineering, 2Graduate School of Engineering, Chiba University, Chiba, Japan Abstract: Unlike forearm amputees, transhumeral amputees have residual stumps that are too small to provide a sufficient range of operation for their prosthetic parts to perform usual activities of daily living. Furthermore, it is difficult for small residual stumps to provide sufficient impact absorption for safe manipulation in daily living, as intact arms do. Therefore, substitution of upper limb function in transhumeral amputees requires a sufficient range of motion and sufficient viscoelasticity for shoulder prostheses under critical weight and dimension constraints. We propose the use of two different types of actuators, ie, pneumatic elastic actuators (PEAs and servo motors. PEAs offer high power-to-weight performance and have intrinsic viscoelasticity in comparison with motors or standard industrial pneumatic cylinder actuators. However, the usefulness of PEAs in large working spaces is limited because of their short strokes. Servo motors, in contrast, can be used to achieve large ranges of motion. In this study, the relationship between the force and stroke of PEAs was investigated. The impact absorption of both types of actuators was measured using a single degree-of-freedom prototype to evaluate actuator compliance for safety purposes. Based on the fundamental properties of the actuators identified, a four degree-of-freedom robotic arm is proposed for prosthetic use. The configuration of the actuators and functional parts was designed to achieve a specified range of motion and torque calculated from the results of a simulation of typical movements performed in usual activities of daily living. Our experimental results showed that the requirements for the shoulder prostheses could be satisfied. Keywords: shoulder prosthesis, hybrid actuation, pneumatic elastic actuator, antagonistic

  12. A Systems Engineering Approach to Electro-Mechanical Actuator Diagnostic and Prognostic Development

    Data.gov (United States)

    National Aeronautics and Space Administration — The authors have formulated a Comprehensive Systems Engineering approach to Electro-Mechanical Actuator (EMA) Prognostics and Health Management (PHM) system...

  13. Mechanical stretching effect on the actuator performance of cellulose electroactive paper

    International Nuclear Information System (INIS)

    Kim, Jung-Hwan; Yun, Ki-Ju; Kim, Joo-Hyung; Kim, Jaehwan

    2009-01-01

    The mechanical stretching effect on the actuating performance of electroactive cellulose paper (EAPap) was studied. A lattice elongation of cellulose fibrils due to in-plane tensile stress along the stretching direction was observed by the x-ray diffraction method. The shrinkage of the fibril diameter as a function of stretching ratio was confirmed by surface and cross-sectional images. While the actuator performance in terms of bending displacement decreased as the stretching ratio increased, the resonance frequency linearly increased as the stretching ratio increased, which was compared with the theoretical frequency data found from a cantilever beam model. The actuator efficiency was evaluated from the electrical input power consumption and the mechanical output power of an EAPap actuator. It was revealed that the stretching process increased the electro-mechanical efficiency of the EAPap actuator. The mechanism of the influence of the stretching effect on the performance of an EAPap actuator is discussed

  14. Extended state observer-based motion synchronisation control for hybrid actuation system of large civil aircraft

    Science.gov (United States)

    Wang, Xingjian; Shi, Cun; Wang, Shaoping

    2017-07-01

    Hybrid actuation system with dissimilar redundant actuators, which is composed of a hydraulic actuator (HA) and an electro-hydrostatic actuator (EHA), has been applied on modern civil aircraft to improve the reliability. However, the force fighting problem arises due to different dynamic performances between HA and EHA. This paper proposes an extended state observer (ESO)-based motion synchronisation control method. To cope with the problem of unavailability of the state signals, the well-designed ESO is utilised to observe the HA and EHA state variables which are unmeasured. In particular, the extended state of ESO can estimate the lumped effect of the unknown external disturbances acting on the control surface, the nonlinear dynamics, uncertainties, and the coupling term between HA and EHA. Based on the observed states of ESO, motion synchronisation controllers are presented to make HA and EHA to simultaneously track the desired motion trajectories, which are generated by a trajectory generator. Additionally, the unknown disturbances and the coupling terms can be compensated by using the extended state of the proposed ESO. Finally, comparative simulation results indicate that the proposed ESO-based motion synchronisation controller can achieve great force fighting reduction between HA and EHA.

  15. Nonlinear Mechanics of MEMS Rectangular Microplates under Electrostatic Actuation

    KAUST Repository

    Saghir, Shahid

    2016-12-01

    The first objective of the dissertation is to develop a suitable reduced order model capable of investigating the nonlinear mechanical behavior of von-Karman plates under electrostatic actuation. The second objective is to investigate the nonlinear static and dynamic behavior of rectangular microplates under small and large actuating forces. In the first part, we present and compare various approaches to develop reduced order models for the nonlinear von-Karman rectangular microplates actuated by nonlinear electrostatic forces. The reduced-order models aim to investigate the static and dynamic behavior of the plate under small and large actuation forces. A fully clamped microplate is considered. Different types of basis functions are used in conjunction with the Galerkin method to discretize the governing equations. First we investigate the convergence with the number of modes retained in the model. Then for validation purpose, a comparison of the static results is made with the results calculated by a nonlinear finite element model. The linear eigenvalue problem for the plate under the electrostatic force is solved for a wide range of voltages up to pull-in. In the second part, we present an investigation of the static and dynamic behavior of a fully clamped microplate. We investigate the effect of different non-dimensional design parameters on the static response. The forced-vibration response of the plate is then investigated when the plate is excited by a harmonic AC load superimposed to a DC load. The dynamic behavior is examined near the primary and secondary (superharmonic and subharmonic) resonances. The microplate shows a strong hardening behavior due to the cubic nonlinearity of midplane stretching. However, the behavior switches to softening as the DC load is increased. Next, near-square plates are studied to understand the effect of geometric imperfections of microplates. In the final part of the dissertation, we investigate the mechanical behavior of

  16. A mechanical model of a non-uniform ionomeric polymer metal composite actuator

    International Nuclear Information System (INIS)

    Anton, Mart; Aabloo, Alvo; Punning, Andres; Kruusmaa, Maarja

    2008-01-01

    This paper describes a mechanical model of an IPMC (ionomeric polymer metal composite) actuator in a cantilever beam configuration. The main contribution of our model is that it gives the most detailed description reported so far of the quasistatic mechanical behaviour of the actuator with non-uniform bending at large deflections. We also investigate a case where part of an IPMC actuator is replaced with a rigid elongation and demonstrate that this configuration would make the actuator behave more linearly. The model is experimentally validated with MuscleSheet(TM) IPMCs, purchased from BioMimetics Inc

  17. A study on flow distribution for integrated hybrid actuator by analysis of reed valve

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Jang Mi; Kang, Seung Hwan; Ko, Han Seo [Sungkyunkwan University, Suwon (Korea, Republic of); Goo, Nam Seo; Li, Yong Zhe [Konkuk University, Seoul (Korea, Republic of)

    2016-05-15

    Many studies have been conducted recently on an integrated hybrid actuator due to the increasing need for unmanned aircraft and guided weapons. In this study, flow distribution was analyzed for a reed valve which was used for flow regulation to improve the performance of the actuator. By using a Fluid structural interaction (FSI) technique with Computational fluid dynamics (CFD) having a moving mesh, numerical analysis was performed according to the thickness, shape and driving frequency of the reed valve. From the calculated results, the maximum performance of the reed valve was found at the valve thickness of 0.15 mm and the driving frequency of 250 Hz for a no-load state. The optimum thickness and shape for the valve for each driving frequency were also realized.

  18. Feedforward-feedback hybrid control for magnetic shape memory alloy actuators based on the Krasnosel'skii-Pokrovskii model.

    Directory of Open Access Journals (Sweden)

    Miaolei Zhou

    Full Text Available As a new type of smart material, magnetic shape memory alloy has the advantages of a fast response frequency and outstanding strain capability in the field of microdrive and microposition actuators. The hysteresis nonlinearity in magnetic shape memory alloy actuators, however, limits system performance and further application. Here we propose a feedforward-feedback hybrid control method to improve control precision and mitigate the effects of the hysteresis nonlinearity of magnetic shape memory alloy actuators. First, hysteresis nonlinearity compensation for the magnetic shape memory alloy actuator is implemented by establishing a feedforward controller which is an inverse hysteresis model based on Krasnosel'skii-Pokrovskii operator. Secondly, the paper employs the classical Proportion Integration Differentiation feedback control with feedforward control to comprise the hybrid control system, and for further enhancing the adaptive performance of the system and improving the control accuracy, the Radial Basis Function neural network self-tuning Proportion Integration Differentiation feedback control replaces the classical Proportion Integration Differentiation feedback control. Utilizing self-learning ability of the Radial Basis Function neural network obtains Jacobian information of magnetic shape memory alloy actuator for the on-line adjustment of parameters in Proportion Integration Differentiation controller. Finally, simulation results show that the hybrid control method proposed in this paper can greatly improve the control precision of magnetic shape memory alloy actuator and the maximum tracking error is reduced from 1.1% in the open-loop system to 0.43% in the hybrid control system.

  19. Feedforward-feedback hybrid control for magnetic shape memory alloy actuators based on the Krasnosel'skii-Pokrovskii model.

    Science.gov (United States)

    Zhou, Miaolei; Zhang, Qi; Wang, Jingyuan

    2014-01-01

    As a new type of smart material, magnetic shape memory alloy has the advantages of a fast response frequency and outstanding strain capability in the field of microdrive and microposition actuators. The hysteresis nonlinearity in magnetic shape memory alloy actuators, however, limits system performance and further application. Here we propose a feedforward-feedback hybrid control method to improve control precision and mitigate the effects of the hysteresis nonlinearity of magnetic shape memory alloy actuators. First, hysteresis nonlinearity compensation for the magnetic shape memory alloy actuator is implemented by establishing a feedforward controller which is an inverse hysteresis model based on Krasnosel'skii-Pokrovskii operator. Secondly, the paper employs the classical Proportion Integration Differentiation feedback control with feedforward control to comprise the hybrid control system, and for further enhancing the adaptive performance of the system and improving the control accuracy, the Radial Basis Function neural network self-tuning Proportion Integration Differentiation feedback control replaces the classical Proportion Integration Differentiation feedback control. Utilizing self-learning ability of the Radial Basis Function neural network obtains Jacobian information of magnetic shape memory alloy actuator for the on-line adjustment of parameters in Proportion Integration Differentiation controller. Finally, simulation results show that the hybrid control method proposed in this paper can greatly improve the control precision of magnetic shape memory alloy actuator and the maximum tracking error is reduced from 1.1% in the open-loop system to 0.43% in the hybrid control system.

  20. An advanced pitch change mechanism incorporating a hybrid traction drive

    Science.gov (United States)

    Steinetz, B. M.; Loewenthal, S. H.; Sargisson, D. F.; White, G.

    1984-01-01

    A design of a propeller pitch control mechanism is described that meets the demanding requirements of a high-power, advanced turboprop. In this application, blade twisting moment torque can be comparable to that of the main reduction gearbox output: precise pitch control, reliability and compactness are all at a premium. A key element in the design is a compact, high-ratio hybrid traction drive which offers low torque ripple and high torsional stiffness. The traction drive couples a high speed electric motor/alternator unit to a ball screw that actuates the blade control links. The technical merits of this arrangement and the performance characteristics of the traction drive are discussed.

  1. A new method for fluid input into a hybrid synthetic jet actuator

    Directory of Open Access Journals (Sweden)

    Kordík J.

    2014-03-01

    Full Text Available A new principle of flow rectification for hybrid synthetic jet actuators is introduced in this paper. As is well known, the flow rectification can be best accomplished by means of fluidic diodes. Novelty of the present study are fluidic diodes with two mutually opposed nozzles. Interaction between the periodic jet flows from the nozzles causes a difference between the blowing and suction strokes, resulting in a particularly efficient rectification effect. The distance between the nozzle exits as well as the oscillation frequency were the parameters, which were varied during hot-wire measurements. The combination of those parameters achieving the highest volumetric effciency was identified.

  2. Improved Advanced Actuated Hybrid Mirrors Final Report CRADA No. TC02130.0

    Energy Technology Data Exchange (ETDEWEB)

    Barbee, T. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ealey, M. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-08-25

    This was a collaborative effort to develop and demonstrate an improved Advanced Actuated Hybrid Mirrors (AAHM) for commercial or Government purposes. The AAHM consists of a nanolaminate film replicating a precision optical surface bonded to a Silicon Carbide (SiC) substrate with active figure control capability. The goal of this project was to further the development of specific AAHM technologies. The intent of the CRADA was to combine the expertise of LLNL and NG Xinetics in the manufacture and test of a very high quality AAHM, incorporating lessons learned from earlier joint efforts.

  3. A novel variable stiffness mechanism for dielectric elastomer actuators

    Science.gov (United States)

    Li, Wen-Bo; Zhang, Wen-Ming; Zou, Hong-Xiang; Peng, Zhi-Ke; Meng, Guang

    2017-08-01

    In this paper, a novel variable stiffness mechanism is proposed for the design of a variable stiffness dielectric elastomer actuator (VSDEA) which combines a flexible strip with a DEA in a dielectric elastomer minimum energy structure. The DEA induces an analog tuning of the transverse curvature of the strip, thus conveniently providing a voltage-controllable flexural rigidity. The VSDEA tends to be a fully flexible and compact structure with the advantages of simplicity and fast response. Both experimental and theoretical investigations are carried out to reveal the variable stiffness performances of the VSDEA. The effect of the clamped location on the bending stiffness of the VSDEA is analyzed, and then effects of the lengths, the loading points and the applied voltages on the bending stiffness are experimentally investigated. An analytical model is developed to verify the availability of this variable stiffness mechanism, and the theoretical results demonstrate that the bending stiffness of the VSDEA decreases as the applied voltage increases, which agree well with the experimental data. Moreover, the experimental results show that the maximum change of the relative stiffness can reach about 88.80%. It can be useful for the design and optimization of active variable stiffness structures and DEAs for soft robots, vibration control, and morphing applications.

  4. The analysis of actuating mechanism and review of concepts for the vortex valve

    International Nuclear Information System (INIS)

    Park, Jong Kyun; Sim, Yun Seop; Joung, Sae Won; Lee, Ki Young; Lee, Jun; Kim, Young In

    1995-12-01

    To understand the basic features of the passive fluidic device, which is increasing available core cooling water from the safety injection tanks in the KNGR, review of the existing vortex valves concepts and analysis of the actuating mechanism of them have been performed and the results are as following: * Preliminary methodology development for parallel two water columns behavior, which is similar to the SIT valve actuation condition * Preliminary methodology for the vortex value actuation features * Analysis of the parallel water columns behavior and vortex valve actuation features using the results of above activities * Further works to be done in the analytical methodology. 16 figs., 2 refs. (Author) .new

  5. Mechanical and thermal design of hybrid blankets

    International Nuclear Information System (INIS)

    Schultz, K.R.

    1978-01-01

    The thermal and mechanical aspects of hybrid reactor blanket design considerations are discussed. This paper is intended as a companion to that of J. D. Lee of Lawrence Livermore Laboratory on the nuclear aspects of hybrid reactor blanket design. The major design characteristics of hybrid reactor blankets are discussed with emphasis on the areas of difference between hybrid reactors and standard fusion or fission reactors. Specific examples are used to illustrate the design tradeoffs and choices that must be made in hybrid reactor design. These examples are drawn from the work on the Mirror Hybrid Reactor

  6. Characteristic Evaluation of a Shrouded Propeller Mechanism for a Magnetic Actuated Microrobot

    Directory of Open Access Journals (Sweden)

    Qiang Fu

    2015-09-01

    Full Text Available Medical microrobots have been widely used in clinical applications, particularly the spiral type locomotion mechanism, which was recently considered one of the main self-propelling mechanisms for the next medical microrobot to perform tasks such as capsule endoscopy and drug delivery. However, limits in clinical applications still exist. The spiral action of the microrobot while being used for diagnosis may lead to pain or even damage to the intestinal wall due to the exposed mechanisms. Therefore, a new locomotive mechanism, named the shrouded propeller mechanism, was proposed to achieve a high level of medical safety as well as effective propulsive performance in our study. The shrouded propeller mechanism consists of a bare spiral propeller and a non-rotating nozzle. To obtain a high effective propulsive performance, two types of screw grooves with different shapes including the cylindrical screw groove and the rectangular screw groove with different parameters were analyzed using the shrouded model. Two types of magnetic actuated microrobots with different driving modes, the electromagnetic (three-pole rotor actuated microrobot and the permanent magnet (O-ring type magnet actuated microrobot were designed to evaluate the performance of the electromagnetic actuation system. Based on experimental results, the propulsive force of the proposed magnetic actuated microrobot with a shrouded propeller was larger than the magnetic actuated microrobot with a bare spiral propeller under the same parameters. Additionally, the shrouded propeller mechanism as an actuator can be used for other medical microrobots for flexible locomotion.

  7. Self-actuation type electromagnet for control rod retaining mechanism

    International Nuclear Information System (INIS)

    Saito, Makoto; Gunji, Minoru.

    1989-01-01

    The present invention concerns a self-actuation type electromagnet for automatically inserting a control rod into a reactor core for the reactor scram upon occurrence of abnormality in FBR type reactors, etc. That is, a mechanism for preventing scorching is disposed to an attracting portion of a split type core thereby enabling reliable detachment of a control rod. For this purpose, less scorching material is embedded to the attracting portion between each of the core portions, with the surface being slightly protruded. In such an attracting portion, a fine gap is formed between each of the core portions by the contact of less scorching materials. Further, the scorching material is embedded into a metal ring, which is screw-coupled to one of the core portions such that the position is adjustable in the direction of the control rod. Further, the less scorching material is made of alumina. As a result, the attracting portion is neither scorched or fused even when it is used for a long period of time in liquid sodium at high temperature. Therefore, when the electromagnet loses the attracting force, the control rod drops surely. (I.S.)

  8. Aerodynamic Optimization for Distributed Electro Mechanical Actuators, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Traditional hydraulic actuation and control surface layout both limit span wise control of lift distribution, and require large volume within wing cross-section,...

  9. Numerical optimization of actuator trajectories for ITER hybrid scenario profile evolution

    International Nuclear Information System (INIS)

    Dongen, J van; Hogeweij, G M D; Felici, F; Geelen, P; Maljaars, E

    2014-01-01

    Optimal actuator trajectories for an ITER hybrid scenario ramp-up are computed using a numerical optimization method. For both L-mode and H-mode scenarios, the time trajectory of plasma current, EC heating and current drive distribution is determined that minimizes a chosen cost function, while satisfying constraints. The cost function is formulated to reflect two desired properties of the plasma q profile at the end of the ramp-up. The first objective is to maximize the ITG turbulence threshold by maximizing the volume-averaged s/q ratio. The second objective is to achieve a stationary q profile by having a flat loop voltage profile. Actuator and physics-derived constraints are included, imposing limits on plasma current, ramp rates, internal inductance and q profile. This numerical method uses the fast control-oriented plasma profile evolution code RAPTOR, which is successfully benchmarked against more complete CRONOS simulations for L-mode and H-mode mode ITER hybrid scenarios. It is shown that the optimized trajectories computed using RAPTOR also result in an improved ramp-up scenario for CRONOS simulations using the same input trajectories. Furthermore, the optimal trajectories are shown to vary depending on the precise timing of the L–H transition. (paper)

  10. Demonstration of Vibrational Braille Code Display Using Large Displacement Micro-Electro-Mechanical Systems Actuators

    Science.gov (United States)

    Watanabe, Junpei; Ishikawa, Hiroaki; Arouette, Xavier; Matsumoto, Yasuaki; Miki, Norihisa

    2012-06-01

    In this paper, we present a vibrational Braille code display with large-displacement micro-electro-mechanical systems (MEMS) actuator arrays. Tactile receptors are more sensitive to vibrational stimuli than to static ones. Therefore, when each cell of the Braille code vibrates at optimal frequencies, subjects can recognize the codes more efficiently. We fabricated a vibrational Braille code display that used actuators consisting of piezoelectric actuators and a hydraulic displacement amplification mechanism (HDAM) as cells. The HDAM that encapsulated incompressible liquids in microchambers with two flexible polymer membranes could amplify the displacement of the MEMS actuator. We investigated the voltage required for subjects to recognize Braille codes when each cell, i.e., the large-displacement MEMS actuator, vibrated at various frequencies. Lower voltages were required at vibration frequencies higher than 50 Hz than at vibration frequencies lower than 50 Hz, which verified that the proposed vibrational Braille code display is efficient by successfully exploiting the characteristics of human tactile receptors.

  11. Structural integrity and failure mechanisms of a smart piezoelectric actuator under a cyclic bending mode

    International Nuclear Information System (INIS)

    Woo, Sung-Choong; Goo, Nam Seo

    2008-01-01

    Information on the onset and evolution of damage within materials is essential for guaranteeing the integrity of actuator systems. The authors have evaluated the structural integrity and the failure mechanisms of smart composite actuators with a PZT ceramic plate under electric cyclic loading. For this, two kinds of actuators, actuator 1 and actuator 2, were manufactured. Prior to the main testing, performance testing was performed on the actuators to determine their resonant frequencies. Electric cyclic tests were conducted up to twenty million cycles. An acoustic emission technique was used for monitoring the damage evolution in real time. We observed the extent of the damage after testing using scanning electron microscopy and reflected optical microscopy to support characteristics in the acoustic emission behavior that corresponded to specific types of damage mechanisms. It was shown that the initial damage mechanism of the smart composite actuator under electric cyclic loading originated from the transgranular micro-fatigue damage in the PZT ceramic layer. With increasing cycles, a local intergranular crack initiated and developed onto the surface of the PZT ceramic layer or propagated into the internal layer. Finally, short-circuiting led to the electric breakdown of the actuator. These results were different depending on the drive frequencies and the configuration of the actuators. Moreover, we differentiated between the aforementioned damage mechanisms via AE signal pattern analyses based on the primary frequency and the waveform. From our results, we conclude that the drive frequency and the existence of a protecting layer are dominant factors in the structural integrity of the smart composite actuator

  12. Parallel kinematic mechanisms for distributed actuation of future structures

    Science.gov (United States)

    Lai, G.; Plummer, A. R.; Cleaver, D. J.; Zhou, H.

    2016-09-01

    Future machines will require distributed actuation integrated with load-bearing structures, so that they are lighter, move faster, use less energy, and are more adaptable. Good examples are shape-changing aircraft wings which can adapt precisely to the ideal aerodynamic form for current flying conditions, and light but powerful robotic manipulators which can interact safely with human co-workers. A 'tensegrity structure' is a good candidate for this application due to its potentially excellent stiffness and strength-to-weight ratio and a multi-element structure into which actuators could be embedded. This paper presents results of an analysis of an example practical actuated tensegrity structure consisting of 3 ‘unit cells’. A numerical method is used to determine the stability of the structure with varying actuator length, showing how four actuators can be used to control movement in three degrees of freedom as well as simultaneously maintaining the structural pre-load. An experimental prototype has been built, in which 4 pneumatic artificial muscles (PAMs) are embedded in one unit cell. The PAMs are controlled antagonistically, by high speed switching of on-off valves, to achieve control of position and structure pre-load. Experimental and simulation results are presented, and future prospects for the approach are discussed.

  13. Attitude control for on-orbit servicing spacecraft using hybrid actuator

    Science.gov (United States)

    Wu, Yunhua; Han, Feng; Zheng, Mohong; He, Mengjie; Chen, Zhiming; Hua, Bing; Wang, Feng

    2018-03-01

    On-orbit servicing is one of the research hotspots of space missions. A small satellite equipped with multiple robotic manipulators is expected to carry out device replacement task for target large spacecraft. Attitude hyperstable control of a small satellite platform under rotations of the manipulators is a challenging problem. A hybrid momentum exchanging actuator consists of Control Moment Gyro (CMG) and Reaction Wheel (RW) is proposed to tackle the above issue, due to its huge amount of momentum storage capacity of the CMG and high control accuracy of the RW, in which the CMG produces large command torque while the RW offers additional control degrees. The constructed dynamic model of the servicing satellite advises that it's feasible for attitude hyperstable control of the platform with arbitrary manipulators through compensating the disturbance generated by rapid rotation of the manipulators. Then, null motion between the CMG and RW is exploited to drive the system to the expected target with favorable performance, and to overcome the CMG inherent geometric singularity and RW saturation. Simulations with different initial situations, including CMG hyperbolic and elliptic singularities and RW saturation, are executed. Compared to the scenarios where the CMG or RW fails stabilizing the platform, large control torque, precise control effect and escape of singularity are guaranteed by the introduced hybrid actuator, CMGRW (CMGRW refers to the hybrid momentum exchanging devices in this paper, consisting of 4 CMGs in classical pyramid cluster and 3 RWs in an orthogonal group (specific description can been found in Section 4)). The feasible performance of the satellite, CMG and RW under large disturbance demonstrates that the control architecture proposed is capable of attitude control for on-orbit servicing satellite with multiple robotic manipulators.

  14. Humidity Responsive Photonic Sensor based on a Carboxymethyl Cellulose Mechanical Actuator

    OpenAIRE

    Hartings, Matthew; Douglass, Kevin O.; Neice, Claire; Ahmed, Zeeshan

    2017-01-01

    We describe an intuitive and simple method for exploiting humidity-driven volume changes in carboxymethyl cellulose (CMC) to fabricate a humidity responsive actuator on a glass fiber substrate. We optimize this platform to generate a photonic-based humidity sensor where CMC coated on a fiber optic containing a fiber Bragg grating (FBG) actuates a mechanical strain in response to humidity changes. The humidity-driven mechanical deformation of the FBG results in a large lin...

  15. Model-Based Evolution of a Fast Hybrid Fuzzy Adaptive Controller for a Pneumatic Muscle Actuator

    Directory of Open Access Journals (Sweden)

    Alexander Hošovský

    2012-07-01

    Full Text Available Pneumatic artificial muscle-based robotic systems usually necessitate the use of various nonlinear control techniques in order to improve their performance. Their robustness to parameter variation, which is generally difficult to predict, should also be tested. Here a fast hybrid adaptive control is proposed, where a conventional PD controller is placed into the feedforward branch and a fuzzy controller is placed into the adaptation branch. The fuzzy controller compensates for the actions of the PD controller under conditions of inertia moment variation. The fuzzy controller of Takagi-Sugeno type is evolved through a genetic algorithm using the dynamic model of a pneumatic muscle actuator. The results confirm the capability of the designed system to provide robust performance under the conditions of varying inertia.

  16. Improved hybrid isolator with maglev actuator integrated in air spring for active-passive isolation of ship machinery vibration

    Science.gov (United States)

    Li, Yan; He, Lin; Shuai, Chang-geng; Wang, Chun-yu

    2017-10-01

    A hybrid isolator consisting of maglev actuator and air spring is proposed and developed for application in active-passive vibration isolation system of ship machinery. The dynamic characteristics of this hybrid isolator are analyzed and tested. The stability and adaptability of this hybrid isolator to shock and swing in the marine environment are improved by a compliant gap protection technique and a disengageable suspended structure. The functions of these new engineering designs are proved by analytical verification and experimental validation of the designed stiffness of such a hybrid isolator, and also by shock adaptability testing of the hybrid isolator. Finally, such hybrid isolators are installed in an engineering mounting loaded with a 200-kW ship diesel generator, and the broadband and low-frequency sinusoidal isolation performance is tested.

  17. A novel 3D-printed mechanical actuator using centrifugal force for magnetic resonance elastography.

    Science.gov (United States)

    Neumann, Wiebke; Schad, Lothar R; Zollner, Frank G

    2017-07-01

    Magnetic resonance elastography (MRE) is a technique for the quantification of tissue stiffness during MR examinations. It requires consistent methods for mechanical shear wave induction to the region of interest in the human body to reliably quantify elastic properties of soft tissues. This work proposes a novel 3D-printed mechanical actuator using the principle of centrifugal force for wave induction. The driver consists of a 3D-printed turbine vibrator powered by compressed air (located inside the scanner room) and an active driver controlling the pressure of inflowing air (placed outside the scanner room). The generated force of the proposed actuator increases for higher actuation frequencies as opposed to conventionally used air cushions. There, the displacement amplitude decreases with increasing actuation frequency resulting in a smaller signal-to-noise ratio. An initial phantom study is presented which demonstrates the feasibility of the actuator for MRE. The wave-actuation frequency was regulated in a range between 15 Hz and 60 Hz for force measurements and proved sufficiently stable (± 0.3 Hz) for any given nominal frequency. The generated forces depend on the weight of the eccentric unbalance within the turbine and ranged between 0.67 N to 2.70 N (for 15 Hz) and 3.09 N to 7.77 N (for 60 Hz). Therefore, the generated force of the presented actuator increases with rotational speed of the turbine and offers an elegant solution for sufficiently large wave actuation at higher frequencies. In future work, we will investigate an optimal ratio of the weight of unbalance to the size of turbine for appropriately large but tolerable wave actuation for a given nominal frequency.

  18. Bio-inspired passive actuator simulating an abalone shell mechanism for structural control

    International Nuclear Information System (INIS)

    Yang, Henry T Y; Lin, Chun-Hung; Bridges, Daniel; Randall, Connor J; Hansma, Paul K

    2010-01-01

    An energy dispersion mechanism called 'sacrificial bonds and hidden length', which is found in some biological systems, such as abalone shells and bones, is the inspiration for new strategies for structural control. Sacrificial bonds and hidden length can substantially increase the stiffness and enhance energy dissipation in the constituent molecules of abalone shells and bone. Having been inspired by the usefulness and effectiveness of such a mechanism, which has evolved over millions of years and countless cycles of evolutions, the authors employ the conceptual underpinnings of this mechanism to develop a bio-inspired passive actuator. This paper presents a fundamental method for optimally designing such bio-inspired passive actuators for structural control. To optimize the bio-inspired passive actuator, a simple method utilizing the force–displacement–velocity (FDV) plots based on LQR control is proposed. A linear regression approach is adopted in this research to find the initial values of the desired parameters for the bio-inspired passive actuator. The illustrative examples, conducted by numerical simulation with experimental validation, suggest that the bio-inspired passive actuator based on sacrificial bonds and hidden length may be comparable in performance to state-of-the-art semi-active actuators

  19. Bio-inspired passive actuator simulating an abalone shell mechanism for structural control

    Science.gov (United States)

    Yang, Henry T. Y.; Lin, Chun-Hung; Bridges, Daniel; Randall, Connor J.; Hansma, Paul K.

    2010-10-01

    An energy dispersion mechanism called 'sacrificial bonds and hidden length', which is found in some biological systems, such as abalone shells and bones, is the inspiration for new strategies for structural control. Sacrificial bonds and hidden length can substantially increase the stiffness and enhance energy dissipation in the constituent molecules of abalone shells and bone. Having been inspired by the usefulness and effectiveness of such a mechanism, which has evolved over millions of years and countless cycles of evolutions, the authors employ the conceptual underpinnings of this mechanism to develop a bio-inspired passive actuator. This paper presents a fundamental method for optimally designing such bio-inspired passive actuators for structural control. To optimize the bio-inspired passive actuator, a simple method utilizing the force-displacement-velocity (FDV) plots based on LQR control is proposed. A linear regression approach is adopted in this research to find the initial values of the desired parameters for the bio-inspired passive actuator. The illustrative examples, conducted by numerical simulation with experimental validation, suggest that the bio-inspired passive actuator based on sacrificial bonds and hidden length may be comparable in performance to state-of-the-art semi-active actuators.

  20. Design and testing of shape memory alloy actuation mechanism for flapping wing micro unmanned aerial vehicles

    Science.gov (United States)

    Kamaruzaman, N. F.; Abdullah, E. J.

    2017-12-01

    Shape memory alloy (SMA) actuator offers great solution for aerospace applications with low weight being its most attractive feature. A SMA actuation mechanism for the flapping micro unmanned aerial vehicle (MAV) is proposed in this study, where SMA material is the primary system that provides the flapping motion to the wings. Based on several established design criteria, a design prototype has been fabricated to validate the design. As a proof of concept, an experiment is performed using an electrical circuit to power the SMA actuator to evaluate the flapping angle. During testing, several problems have been observed and their solutions for future development are proposed. Based on the experiment, the average recorded flapping wing angle is 14.33° for upward deflection and 12.12° for downward deflection. This meets the required design criteria and objective set forth for this design. The results prove the feasibility of employing SMA actuators in flapping wing MAV.

  1. Monitoring of Failure Mechanisms in a Composite Bending Actuator during Cyclic Loading by Acoustic Emission

    Science.gov (United States)

    Woo, Sung-Choong; Goo, Nam Seo

    The objective of this work is to investigate the influence of electromechanical cyclic loading on the performance of a bending piezoelectric composite actuator. We have analyzed the fatigue damage mechanisms in terms of the behavior of the AE event rate. It was found that whether the actuators are subjected to purely electric loading or electromechanical loading, the initial fatigue damage of the bending piezoelectric composite actuator was caused by the transgranular fracture in the PZT ceramic layer; the final failure was caused only in the case of PCAWB under electromechanical loading by a local discharge, which critically affected the performance reduction of the actuators. As the number of cycles increased, a large reduction in displacement performance coincided with a high AE event rate, which was identified via microscopic observations.

  2. Comparing Ns-DBD vs Ac-DBD plasma actuation mechanisms on a NACA 0012 airfoil

    Science.gov (United States)

    Singh, Ashish; Durasiewicz, Claudia; Little, Jesse

    2017-11-01

    A NACA 0012 airfoil is used to study ns-DBD and ac-DBD plasma actuators at a Reynolds number of 740,000 (U∞=40 m/s). Ns-DBD plasma actuators are hypothesized to work on the principle of joule heating whereas ac-DBD actuators add momentum to the flow. Short duration forcing at a time scale much smaller than the convective time based on model chord is employed to study the control mechanism and flow field response. 2-D PIV carried out over a convective time range of 0-10 is used to study the flow structure. The results show the breakup of shear layer vorticity at the point of actuation followed by reattachment to the suction side of the airfoil and finally stall again. These events are very similar between the two actuators and indicate a similar flow response to different perturbation types. The pulse energies are varied and the response shows little change. The results are compared to other transitory separation control studies using more conventional actuators. The detailed study of these two control mechanisms with the separated flow over an airfoil helps to shed light on the evolution of the flow control process. Additional results on a simplified model problem (low speed mixing layer) are included to provide context. Supported by U.S. Army Research Office (W911NF-14-1-0662).

  3. A methodology for identification and control of electro-mechanical actuators.

    Science.gov (United States)

    Tutunji, Tarek A; Saleem, Ashraf

    2015-01-01

    Mechatronic systems are fully-integrated engineering systems that are composed of mechanical, electronic, and computer control sub-systems. These integrated systems use electro-mechanical actuators to cause the required motion. Therefore, the design of appropriate controllers for these actuators are an essential step in mechatronic system design. In this paper, a three-stage methodology for real-time identification and control of electro-mechanical actuator plants is presented, tested, and validated. First, identification models are constructed from experimental data to approximate the plants' response. Second, the identified model is used in a simulation environment for the purpose of designing a suitable controller. Finally, the designed controller is applied and tested on the real plant through Hardware-in-the-Loop (HIL) environment. The described three-stage methodology provides the following practical contributions: •Establishes an easy-to-follow methodology for controller design of electro-mechanical actuators.•Combines off-line and on-line controller design for practical performance.•Modifies the HIL concept by using physical plants with computer control (rather than virtual plants with physical controllers). Simulated and experimental results for two case studies, induction motor and vehicle drive system, are presented in order to validate the proposed methodology. These results showed that electromechanical actuators can be identified and controlled using an easy-to-duplicate and flexible procedure.

  4. Linear Extended State Observer-Based Motion Synchronization Control for Hybrid Actuation System of More Electric Aircraft

    Directory of Open Access Journals (Sweden)

    Xingjian Wang

    2017-10-01

    Full Text Available Moving towards the more electric aircraft (MEA, a hybrid actuator configuration provides an opportunity to introduce electromechanical actuator (EMA into primary flight control. In the hybrid actuation system (HAS, an electro-hydraulic servo actuator (EHSA and an EMA operate on the same control surface. In order to solve force fighting problem in HAS, this paper proposes a novel linear extended state observer (LESO-based motion synchronization control method. To cope with the problem of unavailability of the state signals required by the motion synchronization controller, LESO is designed for EHSA and EMA to observe the state variables. Based on the observed states of LESO, motion synchronization controllers could enable EHSA and EMA to simultaneously track the desired motion trajectories. Additionally, nonlinearities, uncertainties and unknown disturbances as well as the coupling term between EHSA and EMA can be estimated and compensated by using the extended state of the proposed LESO. Finally, comparative simulation results indicate that the proposed LESO-based motion synchronization controller could reduce significant force fighting between EHSA and EMA.

  5. Linear Extended State Observer-Based Motion Synchronization Control for Hybrid Actuation System of More Electric Aircraft

    Science.gov (United States)

    Liao, Rui; Shi, Cun; Wang, Shaoping

    2017-01-01

    Moving towards the more electric aircraft (MEA), a hybrid actuator configuration provides an opportunity to introduce electromechanical actuator (EMA) into primary flight control. In the hybrid actuation system (HAS), an electro-hydraulic servo actuator (EHSA) and an EMA operate on the same control surface. In order to solve force fighting problem in HAS, this paper proposes a novel linear extended state observer (LESO)-based motion synchronization control method. To cope with the problem of unavailability of the state signals required by the motion synchronization controller, LESO is designed for EHSA and EMA to observe the state variables. Based on the observed states of LESO, motion synchronization controllers could enable EHSA and EMA to simultaneously track the desired motion trajectories. Additionally, nonlinearities, uncertainties and unknown disturbances as well as the coupling term between EHSA and EMA can be estimated and compensated by using the extended state of the proposed LESO. Finally, comparative simulation results indicate that the proposed LESO-based motion synchronization controller could reduce significant force fighting between EHSA and EMA. PMID:29068392

  6. A New and Versatile Adjustable Rigidity Actuator with Add-on Locking Mechanism (ARES-XL

    Directory of Open Access Journals (Sweden)

    Manuel Cestari

    2018-01-01

    Full Text Available Adjustable compliant actuators are being designed and implemented in robotic devices because of their ability to minimize large forces due to impacts, to safely interact with the user, and to store and release energy in passive elastic elements. Conceived as a new force-controlled compliant actuator, an adjustable rigidity with embedded sensor and locking mechanism actuator (ARES-XL is presented in this paper. This compliant system is intended to be implemented in a gait exoskeleton for children with neuro muscular diseases (NMDs to exploit the intrinsic dynamics during locomotion. This paper describes the mechanics and initial evaluation of the ARES-XL, a novel variable impedance actuator (VIA that allows the implementation of an add-on locking mechanism to this system, and in combination with its zero stiffness capability and large deflection range, provides this novel joint with improved properties when compared to previous prototypes developed by the authors and other state-of-the-art (SoA devices. The evaluation of the system proves how this design exceeds the main capabilities of a previous prototype as well as providing versatile actuation that could lead to its implementation in multiple joints.

  7. Nanostructured carbon materials based electrothermal air pump actuators

    Science.gov (United States)

    Liu, Qing; Liu, Luqi; Kuang, Jun; Dai, Zhaohe; Han, Jinhua; Zhang, Zhong

    2014-05-01

    Actuator materials can directly convert different types of energy into mechanical energy. In this work, we designed and fabricated electrothermal air pump-type actuators by utilization of various nanostructured carbon materials, including single wall carbon nanotubes (SWCNTs), reduced graphene oxide (r-GO), and graphene oxide (GO)/SWCNT hybrid films as heating elements to transfer electrical stimulus into thermal energy, and finally convert it into mechanical energy. Both the actuation displacement and working temperature of the actuator films show the monotonically increasing trend with increasing driving voltage within the actuation process. Compared with common polymer nanocomposites based electrothermal actuators, our actuators exhibited better actuation performances with a low driving voltage (film actuator due to the intrinsic gas-impermeability nature of graphene platelets. In addition, the high modulus of the r-GO and GO/SWCNT films also guaranteed the large generated stress and high work density. Specifically, the generated stress and gravimetric work density of the GO/SWCNT hybrid film actuator could reach up to more than 50 MPa and 30 J kg-1, respectively, under a driving voltage of 10 V. The resulting stress value is at least two orders of magnitude higher than that of natural muscles (~0.4 MPa).Actuator materials can directly convert different types of energy into mechanical energy. In this work, we designed and fabricated electrothermal air pump-type actuators by utilization of various nanostructured carbon materials, including single wall carbon nanotubes (SWCNTs), reduced graphene oxide (r-GO), and graphene oxide (GO)/SWCNT hybrid films as heating elements to transfer electrical stimulus into thermal energy, and finally convert it into mechanical energy. Both the actuation displacement and working temperature of the actuator films show the monotonically increasing trend with increasing driving voltage within the actuation process. Compared with

  8. Development of a hybrid safety system: Actuation of the secondary automatic depressurization system at an early stage

    International Nuclear Information System (INIS)

    Nishimoto, Masae; Umezawa, Shigemitsu; Okabe, Kazuharu; Matsuoka, Tsuyoshi

    1996-01-01

    A Hybrid Safety System, which is an optimum combination of active and passive safety systems, has been developed in order to improve the safety, reliability and economic features of the next generation of PWRs. The passive safety systems include Automatic primary Depressurization System (ADS), Secondary Automatic Depressurization System (SADS), advanced accumulators, gravity injection system and so on. In this study the authors have improved the actuation logic of the passive safety systems. The original logic in the previous study actuates ADS at an early stage of an event such as a Loss-of-Coolant Accident (LOCA), and this is followed by the actuation of SADS. In this study they divide SADS into two systems. The first, small SADS, uses small valves corresponding to the relief valves of the conventional PWR plants. The second, large SADS, corresponds to the original SADS using multiple valves of large capacity. With the new logic, the passive systems are actuated during a typical small LOCA. Small LOCA analyses using several break areas were performed for a 1,400 MWe PWR plant with a Hybrid Safety System. The results predict that core uncovery does not occur in the case of a relatively small break area and that core heat removal during a small LOCA is improved in comparison with the analyses for conventional PWR plants, where the secondary pressure remains higher during the event. The results also predict that this new logic make it possible to reduce the ADS valve size and the actuation pressure setpoint of the passive safety systems

  9. Methods and apparatus for laser beam scanners with different actuating mechanisms

    Science.gov (United States)

    Chen, Si-hai; Xiang, Si-hua; Wu, Xin; Dong, Shan; Xiao, Ding; Zheng, Xia-wei

    2009-07-01

    In this paper, 3 types of laser beam scanner are introduced. One is transmissive beam scanner, which is composed of convex and concave microlens arrays (MLAs). By moving the concave lens in the plane vertical to the optical axis, the incident beam can be deflected in two dimensions. Those two kinds of MLAs are fabricated by thermal reflow and replication process. A set of mechanical scanner frame is fabricated with the two MLAs assembling in it. The testing result shown that the beam deflection angles are 9.5° and 9.6°, in the 2 dimension(2D) with the scanning frequency of 2 HZ and 8 HZ, respectively. The second type of laser beam scanner is actuated by voice coil actuators (VCAs). Based on ANSOFT MAXWELL software, we have designed VCAs with small size and large force which have optimized properties. The model of VCAs is built using AutoCAD and is analyzed by Ansoft maxwell. According to the simulation results, high performance VCAs are fabricated and tested. The result is that the force of the VCAs is 6.39N/A, and the displacement is +/-2.5mm. A set up of beam scanner is fabricated and actuated by the designed VCAs. The testing result shown that the two dimensional scanning angle is 15° and 10° respectively at the frequency of 60HZ. The two dimensional scanning angle is 8.3° and 6° respectively at the frequency of 100HZ. The third type of scanner is actuated by amplified piezoelectric actuators (APAs). The scanning mirror is actuated by the piezoelectric (PZ) actuators with the scanning frequency of 700HZ, 250HZ and 87HZ respectively. The optical scanning angle is +/-0.5° at the three frequencies.

  10. Modeling Populations of Thermostatic Loads with Switching Rate Actuation

    DEFF Research Database (Denmark)

    Totu, Luminita Cristiana; Wisniewski, Rafal; Leth, John-Josef

    2015-01-01

    We model thermostatic devices using a stochastic hybrid description, and introduce an external actuation mechanism that creates random switch events in the discrete dynamics. We then conjecture the form of the Fokker-Planck equation and successfully verify it numerically using Monte Carlo...... simulations. The actuation mechanism and subsequent modeling result are relevant for power system operation....

  11. The design and testing of a memory metal actuated boom release mechanism

    Science.gov (United States)

    Powley, D. G.; Brook, G. B.

    1979-01-01

    A boom latch and release mechanism was designed, manufactured and tested, based on a specification for the ISEE-B satellite mechanism. From experimental results obtained, it is possible to calculate the energy available and the operating torques which can be achieved from a torsional shape memory element in terms of the reversible strain induced by prior working. Some guidelines to be followed when designing mechanisms actuated by shape memory elements are included.

  12. Centrifugal forming and mechanical properties of silicone-based elastomers for soft robotic actuators

    Science.gov (United States)

    Kulkarni, Parth

    This thesis describes the centrifugal forming and resulting mechanical properties of silicone-based elastomers for the manufacture of soft robotic actuators. This process is effective at removing bubbles that get entrapped within 3D-printed, enclosed molds. Conventional methods for rapid prototyping of soft robotic actuators to remove entrapped bubbles typically involve degassing under vacuum, with open-faced molds that limit the layout of formed parts to raised 2D geometries. As the functionality and complexity of soft robots increase, there is a need to mold complete 3D structures with controlled thicknesses or curvatures on multiples surfaces. In addition, characterization of the mechanical properties of common elastomers for these soft robots has lagged the development of new designs. As such, relationships between resulting material properties and processing parameters are virtually non-existent. One of the goals of this thesis is to provide guidelines and physical insights to relate the design, processing conditions, and resulting properties of soft robotic components to each other. Centrifugal forming with accelerations on the order of 100 g's is capable of forming bubble-free, true 3D components for soft robotic actuators, and resulting demonstrations in this work include an aquatic locomotor, soft gripper, and an actuator that straightens when pressurized. Finally, this work shows that the measured mechanical properties of 3D geometries fabricated within enclosed molds through centrifugal forming possess comparable mechanical properties to vacuumed materials formed from open-faced molds with raised 2D features.

  13. Driving mechanisms of ionic polymer actuators having electric double layer capacitor structures.

    Science.gov (United States)

    Imaizumi, Satoru; Kato, Yuichi; Kokubo, Hisashi; Watanabe, Masayoshi

    2012-04-26

    Two solid polymer electrolytes, composed of a polyether-segmented polyurethaneurea (PEUU) and either a lithium salt (lithium bis(trifluoromethanesulfonyl)amide: Li[NTf2]) or a nonvolatile ionic liquid (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide: [C2mim][NTf2]), were prepared in order to utilize them as ionic polymer actuators. These salts were preferentially dissolved in the polyether phases. The ionic transport mechanism of the polyethers was discussed in terms of the diffusion coefficients and ionic transference numbers of the incorporated ions, which were estimated by means of pulsed-field gradient spin-echo (PGSE) NMR. There was a distinct difference in the ionic transport properties of each polymer electrolyte owing to the difference in the magnitude of interactions between the cations and the polyether. The anionic diffusion coefficient was much faster than that of the cation in the polyether/Li[NTf2] electrolyte, whereas the cation diffused faster than the anion in the polyether/[C2mim][NTf2] electrolyte. Ionic polymer actuators, which have a solid-state electric-double-layer-capacitor (EDLC) structure, were prepared using these polymer electrolyte membranes and ubiquitous carbon materials such as activated carbon and acetylene black. On the basis of the difference in the motional direction of each actuator against applied voltages, a simple model of the actuation mechanisms was proposed by taking the difference in ionic transport properties into consideration. This model discriminated the behavior of the actuators in terms of the products of transference numbers and ionic volumes. The experimentally observed behavior of the actuators was successfully explained by this model.

  14. Mechanism and bias considerations for design of a bi-directional pneumatic artificial muscle actuator

    International Nuclear Information System (INIS)

    Vocke III, Robert D; Wereley, Norman M; Kothera, Curt S

    2014-01-01

    Pneumatic artificial muscles (PAMs), or McKibben actuators, have received considerable attention for robotic manipulators and in aerospace applications due to their similarity to natural muscles. Like natural muscles, PAMs are a purely contractile actuator, so that, in order to produce bi-directional or rotational motion, they must be arranged in an agonist/antagonist pair, which inherently limits the deflection of the system due to the high parasitic stiffness of the antagonistic PAM. This study presents two methods for increasing the performance of an antagonistic PAM system by decreasing the passive parasitic torque, rather than increasing the active torque. The first involves selection of the kinematic mechanism geometry, and the second involves the introduction of bias into the system, both in terms of PAM contraction and passive (antagonistic) PAM pressure. It was found with the proper selection of design parameters, including mechanism geometry, PAM geometry, and bias conditions, that an ideal actuator configuration can be chosen that maximizes deflection for a given arbitrary loading. When comparing a baseline design to an improved design for a simplified case, a nearly 50% increase in maximum deflection was predicted simply by optimizing mechanism geometry and bias contraction. These results were experimentally verified with quasi-static testing that showed a 300% increase in actuator deflection over the baseline design. (paper)

  15. Controllable Lubrication for Main Engine Bearings Using Mechanical and Piezoelectric Actuators

    DEFF Research Database (Denmark)

    Estupinan, Edgar; Santos, Ilmar

    2012-01-01

    Although mechatronic systems are nowadays implemented in a large number of systems in vehicles, active lubrication systems are still incipient in industrial applications. This study is an attempt to extend the active lubrication concept to combustion engines and gives a theoretical contribution...... equations. The global system is numerically solved using as a case study a single-cylinder combustion engine, where the conventional lubrication of the main bearing is modified by applying radial oil injection using piezo-actuated injection. The performance of such a hybrid bearing is compared...

  16. CABLE MECHANISMS USED FOR ACTUATING CAR ELEVATORS WITH 2 AND 4 POLES

    Directory of Open Access Journals (Sweden)

    Dan MESARICI

    2015-05-01

    Full Text Available This paper presents the kinematic scheme and the operating mode of the cable mechanism used for car elevators with 2 and 4 poles. In order to increase the efficiency of the 4- pole elevator, we suggest using a new hoists type cable mechanism, which can multiply the piston travel inside the actuating cylinder twice at the platform level, when lifting and lowering.

  17. Development of the Aquarius Antenna Deployment Mechanisms and Spring/Damper Actuator

    Science.gov (United States)

    Johnson, Joel A.

    2008-01-01

    The Aquarius Instrument s large radar reflector dish needed to be stowed for launch, and then deployed on-orbit. The Deployment Subsystem consisted of a cantilevered boom structure and two single-axis hinge mechanisms to accurately deploy and position the reflector dish relative to the radar feed horns. The cantilevered design demanded high stiffness and accuracy from the deployment mechanism at the root of the boom. A preload-generating end-of-travel latch was also required. To largely eliminate the need for control systems, each deployment mechanism was actuated by a passive spring motor with viscous-fluid damping. Tough requirements and adaptation of a heritage actuator to the new application resulted in numerous challenges. Fabrication, assembly, and testing encountered additional problems, though ultimately the system was demonstrated very successfully. This paper revisits the development to highlight which design concepts worked and the many important lessons learned.

  18. Kinematics of an in-parallel actuated manipulator based on the Stewart platform mechanism

    Science.gov (United States)

    Williams, Robert L., II

    1992-01-01

    This paper presents kinematic equations and solutions for an in-parallel actuated robotic mechanism based on Stewart's platform. These equations are required for inverse position and resolved rate (inverse velocity) platform control. NASA LaRC has a Vehicle Emulator System (VES) platform designed by MIT which is based on Stewart's platform. The inverse position solution is straight-forward and computationally inexpensive. Given the desired position and orientation of the moving platform with respect to the base, the lengths of the prismatic leg actuators are calculated. The forward position solution is more complicated and theoretically has 16 solutions. The position and orientation of the moving platform with respect to the base is calculated given the leg actuator lengths. Two methods are pursued in this paper to solve this problem. The resolved rate (inverse velocity) solution is derived. Given the desired Cartesian velocity of the end-effector, the required leg actuator rates are calculated. The Newton-Raphson Jacobian matrix resulting from the second forward position kinematics solution is a modified inverse Jacobian matrix. Examples and simulations are given for the VES.

  19. Development of a Wave Energy -Responsive Self-Actuated Blade Articulation Mechanism for an OWC Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Francis A. Di Bella

    2010-06-01

    The Phase I SBIR effort completed the feasibility design, fabrication, and wind tunnel testing of a self-actuated blade articulation mechanism that uses a torsion bar and a lightweight airfoil to affect the articulation of the Wells airfoil. The articulation is affected only by the air stream incident on the airfoil. The self-actuating blade eliminates the complex and costly linkage mechanism that is now needed to perform this function on either a variable pitch Wells-type or Dennis-Auld air turbine. Using the results reported by independent researchers, the projected improvement in the Wells-type turbine efficiency is 20-40%, in addition to an increase in the operating air flow range by 50-100%, therefore enabling a smaller or slower single turbine to be used.

  20. Analysis of hybrid electric/thermofluidic inputs for wet shape memory alloy actuators

    Science.gov (United States)

    Flemming, Leslie; Mascaro, Stephen

    2013-01-01

    A wet shape memory alloy (SMA) actuator is characterized by an SMA wire embedded within a compliant fluid-filled tube. Heating and cooling of the SMA wire produces a linear contraction and extension of the wire. Thermal energy can be transferred to and from the wire using combinations of resistive heating and free/forced convection. This paper analyzes the speed and efficiency of a simulated wet SMA actuator using a variety of control strategies involving different combinations of electrical and thermofluidic inputs. A computational fluid dynamics (CFD) model is used in conjunction with a temperature-strain model of the SMA wire to simulate the thermal response of the wire and compute strains, contraction/extension times and efficiency. The simulations produce cycle rates of up to 5 Hz for electrical heating and fluidic cooling, and up to 2 Hz for fluidic heating and cooling. The simulated results demonstrate efficiencies up to 0.5% for electric heating and up to 0.2% for fluidic heating. Using both electric and fluidic inputs concurrently improves the speed and efficiency of the actuator and allows for the actuator to remain contracted without continually delivering energy to the actuator, because of the thermal capacitance of the hot fluid. The characterized speeds and efficiencies are key requirements for implementing broader research efforts involving the intelligent control of electric and thermofluidic networks to optimize the speed and efficiency of wet actuator arrays.

  1. Extended DNA Tile Actuators

    DEFF Research Database (Denmark)

    Kristiansen, Martin; Kryger, Mille; Zhang, Zhao

    2012-01-01

    A dynamic linear DNA tile actuator is expanded to three new structures of higher complexity. The original DNA actuator was constructed from a central roller strand which hybridizes with two piston strands by forming two half-crossover junctions. A linear expansion of the actuator is obtained...

  2. Robust tilt and lock mechanism for hopping actuator

    Energy Technology Data Exchange (ETDEWEB)

    Salton, Jonathan R.; Buerger, Stephen; Dullea, Kevin J.; Marron, Lisa C.; Salisbury, Curt Michael; Spletzer, Barry Louis

    2017-02-07

    A tilt and lock apparatus that includes a tilt servomechanism, a spiral torsion spring, a lock wheel, and a lock hook is described herein. The spiral torsion spring is mechanically coupled to the tilt servomechanism and the lock wheel (which includes an opening). When a shaft is positioned through the opening, rotation of the lock wheel is in unison with rotation of the shaft. An external surface of the lock wheel includes one or more grooves. The lock hook includes a head that engages and disengages the grooves. The lock wheel is stationary when the head engages one of the grooves and is rotatable when the head disengages the grooves. The head and the grooves are geometrically aligned when engaged to prevent creation of a force that acts to disengage the head responsive to an applied force acting on the shaft.

  3. Nanocarbon/elastomer composites: Characterization and applications in photo-mechanical actuation

    Science.gov (United States)

    Loomis, Robert James, III

    The magnitude and direction of photo-mechanical actuation responses generated in carbon nanostructure/elastomer composites depend on applied pre-strains. At low levels of pre-strains (3--9%), actuators show reversible photo-induced expansion while at high levels (15--40%), actuators exhibit reversible contraction. Large, light-induced reversible and elastic responses of graphene nanoplatelet (GNP) polymer composites were demonstrated for the first time, with an extraordinary optical-to-mechanical energy conversion factor (etaM) of 7--9 MPa/W. Following this demonstration, similar elastomeric composite were fabricated with a variety of carbon nanostructures. Investigation into photo-actuation properties of these composites revealed both layer-dependent, as well as dimensionally-dependent responses. For a given carbon concentration, both steady-state photo-mechanical stress response and energy conversion efficiency were found to be directly related to dimensional state of carbon nanostructure additive, with one-dimensional (1D) carbon nanotubes demonstrating the highest responses (˜60 kPa stress and ˜5 x 10-3% efficiency at just 1 wt% loading) and three-dimensional (3D) highly ordered pyrolytic graphite demonstrating the lowest responses. Furthermore, development of an advanced dispersion technique (evaporative mixing) resulted in the ability to fabricate conductive composites. Actuation and relaxation kinetics responses were investigated and found to be related not to dimensionality, but rather the percolation threshold of carbon nanostructure additive in the polymer. Establishing a connective network of carbon nanostructure additive allowed for energy transduction responsible for photo-mechanical effect to activate carbon beyond the infrared (IR) illumination point, resulting in enhanced actuation. Additionally, in the conductive samples photo-conductivity as a function of applied pre-strain was also measured. Photo-conductive response was found to be inversely

  4. Polymer Hydrogel/Polybutadiene/Iron Oxide Nanoparticle Hybrid Actuators for the Characterization of NiTi Implants

    Directory of Open Access Journals (Sweden)

    Aleksandra Jeličić

    2009-03-01

    Full Text Available One of the main issues with the use of nickel titanium alloy (NiTi implants in cardiovascular implants (stents is that these devices must be of very high quality in order to avoid subsequent operations due to failing stents. For small stents with diameters below ca. 2 mm, however, stent characterization is not straightforward. One of the main problems is that there are virtually no methods to characterize the interior of the NiTi tubes used for fabrication of these tiny stents. The current paper reports on a robust hybrid actuator for the characterization of NiTi tubes prior to stent fabrication. The method is based on a polymer/hydrogel/magnetic nanoparticle hybrid material and allows for the determination of the inner diameter at virtually all places in the raw NiTi tubes. Knowledge of the inner structure of the raw NiTi tubes is crucial to avoid regions that are not hollow or regions that are likely to fail due to defects inside the raw tube. The actuator enables close contact of a magnetic polymer film with the inner NiTi tube surface. The magnetic signal can be detected from outside and be used for a direct mapping of the tube interior. As a result, it is possible to detect critical regions prior to expensive and slow stent fabrication processes.

  5. Thermo-mechanical actuator-based miniature tagging module for localization in capsule endoscopy

    Science.gov (United States)

    Chandrappan, Jayakrishnan; Ruiqi, Lim; Su, Nandar; Yen Yi, Germaine Hoe; Vaidyanathan, Kripesh

    2011-04-01

    Capsule endoscopy is a frontline medical diagnostic tool for the gastro intestinal tract disorders. During diagnosis, efficient localization techniques are essential to specify a pathological area that may require further diagnosis or treatment. This paper presents the development of a miniature tagging module that relies on a novel concept to label the region of interest and has the potential to integrate with a capsule endoscope. The tagging module is a compact thermo-mechanical actuator loaded with a biocompatible micro tag. A low power microheater attached to the module serves as the thermal igniter for the mechanical actuator. At optimum temperature, the actuator releases the micro tag instantly and penetrates the mucosa layer of a GI tract, region of interest. Ex vivo animal trials are conducted to verify the feasibility of the tagging module concept. X-ray imaging is used to detect the location of the micro tag embedded in the GI tract wall. The method is successful, and radiopaque micro tags can provide valuable pre-operative position information on the infected area to facilitate further clinical procedures.

  6. Damping control of micromachined lowpass mechanical vibration isolation filters using electrostatic actuation with electronic signal processing

    Science.gov (United States)

    Dean, Robert; Flowers, George; Sanders, Nicole; MacAllister, Ken; Horvath, Roland; Hodel, A. S.; Johnson, Wayne; Kranz, Michael; Whitley, Michael

    2005-05-01

    Some harsh environments, such as those encountered by aerospace vehicles and various types of industrial machinery, contain high frequency/amplitude mechanical vibrations. Unfortunately, some very useful components are sensitive to these high frequency mechanical vibrations. Examples include MEMS gyroscopes and resonators, oscillators and some micro optics. Exposure of these components to high frequency mechanical vibrations present in the operating environment can result in problems ranging from an increased noise floor to component failure. Passive micromachined silicon lowpass filter structures (spring-mass-damper) have been demonstrated in recent years. However, the performance of these filter structures is typically limited by low damping (especially if operated in near-vacuum environments) and a lack of tunability after fabrication. Active filter topologies, such as piezoelectric, electrostrictive-polymer-film and SMA have also been investigated in recent years. Electrostatic actuators, however, are utilized in many micromachined silicon devices to generate mechanical motion. They offer a number of advantages, including low power, fast response time, compatibility with silicon micromachining, capacitive position measurement and relative simplicity of fabrication. This paper presents an approach for realizing active micromachined mechanical lowpass vibration isolation filters by integrating an electrostatic actuator with the micromachined passive filter structure to realize an active mechanical lowpass filter. Although the electrostatic actuator can be used to adjust the filter resonant frequency, the primary application is for increasing the damping to an acceptable level. The physical size of these active filters is suitable for use in or as packaging for sensitive electronic and MEMS devices, such as MEMS vibratory gyroscope chips.

  7. Teleoperation System with Hybrid Pneumatic-Piezoelectric Actuation for MRI-Guided Needle Insertion with Haptic Feedback

    OpenAIRE

    Shang, Weijian; Su, Hao; Li, Gang; Fischer, Gregory S.

    2013-01-01

    This paper presents a surgical master-slave tele-operation system for percutaneous interventional procedures under continuous magnetic resonance imaging (MRI) guidance. This system consists of a piezoelectrically actuated slave robot for needle placement with integrated fiber optic force sensor utilizing Fabry-Perot interferometry (FPI) sensing principle. The sensor flexure is optimized and embedded to the slave robot for measuring needle insertion force. A novel, compact opto-mechanical FPI ...

  8. Performance of synthetic jet actuators based on hybrid and double-acting principles

    Czech Academy of Sciences Publication Activity Database

    Trávníček, Zdeněk; Tesař, Václav; Kordík, Jozef

    2008-01-01

    Roč. 11, č. 3 (2008), s. 221-229 ISSN 1343-8875 R&D Projects: GA ČR GA101/07/1499; GA AV ČR(CZ) IAA200760801 Institutional research plan: CEZ:AV0Z20760514 Keywords : synthetic jet * impinging jet * actuator Subject RIV: BK - Fluid Dynamics Impact factor: 0.943, year: 2008

  9. Magnetic Actuation Connector Between Extension Shaft and Armature for Bottom Mounted Control Rod Drive Mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Hyung; Cho, Yeong Garp; Kim, Jong In [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    The electromagnet and armature inside the guide tube interact and produce magnetism, thus making the armature, connecting extension shaft and control rod move up and down to control the power of reactor. During the overhaul, the control absorber rod (CAR), extension shaft, and armature of BMCRDM are lifted together for closing a seal valve. But total length of CAR assembly is so long that it cannot be lifted due to exposure above the water level of pool which is strictly controlled. In addition to this, it is difficult to calibrate a position indicator and lifting force of electromagnet without armature assembly as a seal valve is closed. For this reason, it is necessary to install a disconnecting system between armature and extension shaft. Therefore, KAERI has developed magnetic actuation connector using plunger between armature and extension shaft for the bottom mounted control rod drive mechanism in research reactor. The results of a FEM and the experiments in this work lead to the following conclusions: The FEM result for the design of the magnetic actuation connector is compared with the measured lifting force of prototype production. As a result, it is shown that the lifting force of the prototype connector has a good agreement with the result of the FEM. A newly developed technique of prototype magnetic actuation connector which is designed by FEM analysis result is proposed.

  10. Magnetic Actuation Connector Between Extension Shaft and Armature for Bottom Mounted Control Rod Drive Mechanism

    International Nuclear Information System (INIS)

    Huh, Hyung; Cho, Yeong Garp; Kim, Jong In

    2013-01-01

    The electromagnet and armature inside the guide tube interact and produce magnetism, thus making the armature, connecting extension shaft and control rod move up and down to control the power of reactor. During the overhaul, the control absorber rod (CAR), extension shaft, and armature of BMCRDM are lifted together for closing a seal valve. But total length of CAR assembly is so long that it cannot be lifted due to exposure above the water level of pool which is strictly controlled. In addition to this, it is difficult to calibrate a position indicator and lifting force of electromagnet without armature assembly as a seal valve is closed. For this reason, it is necessary to install a disconnecting system between armature and extension shaft. Therefore, KAERI has developed magnetic actuation connector using plunger between armature and extension shaft for the bottom mounted control rod drive mechanism in research reactor. The results of a FEM and the experiments in this work lead to the following conclusions: The FEM result for the design of the magnetic actuation connector is compared with the measured lifting force of prototype production. As a result, it is shown that the lifting force of the prototype connector has a good agreement with the result of the FEM. A newly developed technique of prototype magnetic actuation connector which is designed by FEM analysis result is proposed

  11. A phase field approach for the fully coupled thermo-electro-mechanical dynamics of nanoscale ferroelectric actuators

    Science.gov (United States)

    Wang, Dan; Du, Haoyuan; Wang, Linxiang; Melnik, Roderick

    2018-05-01

    The fully coupled thermo-electro-mechanical properties of nanoscale ferroelectric actuators are investigated by a phase field model. Firstly, the thermal effect is incorporated into the commonly-used phase field model for ferroelectric materials in a thermodynamic consistent way and the governing equation for the temperature field is derived. Afterwards, the modified model is numerically implemented to study a selected prototype of the ferroelectric actuators, where strain associated with electric field-induced non-180° domain switching is employed. The temperature variation and energy flow in the actuation process are presented, which enhances our understanding of the working mechanism of the actuators. Furthermore, the influences of the input voltage frequency and the thermal boundary condition on the temperature variation are demonstrated and carefully discussed in the context of thermal management for real applications.

  12. Biological Applications of Hybrid Quantum Mechanics/Molecular Mechanics Calculation

    Directory of Open Access Journals (Sweden)

    Jiyoung Kang

    2012-01-01

    Full Text Available Since in most cases biological macromolecular systems including solvent water molecules are remarkably large, the computational costs of performing ab initio calculations for the entire structures are prohibitive. Accordingly, QM calculations that are jointed with MM calculations are crucial to evaluate the long-range electrostatic interactions, which significantly affect the electronic structures of biological macromolecules. A UNIX-shell-based interface program connecting the quantum mechanics (QMs and molecular mechanics (MMs calculation engines, GAMESS and AMBER, was developed in our lab. The system was applied to a metalloenzyme, azurin, and PU.1-DNA complex; thereby, the significance of the environmental effects on the electronic structures of the site of interest was elucidated. Subsequently, hybrid QM/MM molecular dynamics (MD simulation using the calculation system was employed for investigation of mechanisms of hydrolysis (editing reaction in leucyl-tRNA synthetase complexed with the misaminoacylated tRNALeu, and a novel mechanism of the enzymatic reaction was revealed. Thus, our interface program can play a critical role as a powerful tool for state-of-the-art sophisticated hybrid ab initio QM/MM MD simulations of large systems, such as biological macromolecules.

  13. Fatigue response of a PZT multilayer actuator under high-field electric cycling with mechanical preload

    Science.gov (United States)

    Wang, Hong; Wereszczak, Andrew A.; Lin, Hua-Tay

    2009-01-01

    An electric fatigue test system was developed for evaluating the reliability of piezoelectric actuators with a mechanical loading capability. Fatigue responses of a lead zirconate titanate (PZT) multilayer actuator with a platethrough electrode configuration were studied under an electric field (1.7 times that of the coercive field of PZT material) and a concurrent mechanical preload (30.0 MPa). A total of 109 cycles was carried out. Variations in charge density and mechanical strain under the high electric field and constant mechanical loads were observed during the fatigue test. The dc and the first harmonic (at 10 Hz) dielectric and piezoelectric coefficients were subsequently characterized using fast Fourier transformation. Both the dielectric and the piezoelectric coefficients exhibited a monotonic decrease prior to 2.86×108 cycles under certain preloading conditions, and then fluctuated. Both the dielectric loss tangent and the piezoelectric loss tangent also fluctuated after a decrease. The results are interpreted and discussed with respect to domain wall activities, microdefects, and other anomalies.

  14. Mechanical characterization of bucky gel morphing nanocomposite for actuating/sensing applications

    International Nuclear Information System (INIS)

    Ghamsari, Ali Kadkhoda; Woldesenbet, Eyassu; Jin, Yoonyoung

    2012-01-01

    Since the demonstration of the bucky gel actuator (BGA) in 2005, a great deal of effort has been exerted to develop novel applications for this electro-active morphing nanocomposite. This three-layered bimorph nanocomposite can be easily fabricated, operated in air and driven with a few volts. The BGA with improved mechanical strength is an excellent candidate for application in macro- to micro-scale smart structures with actuating and sensing capabilities. However, developing new applications requires identifying and understanding the effective design parameters and mechanical properties, respectively. There has been limited published studies on the mechanical properties of BGA. In this study, the effect of three parameters—layer thickness, carbon nanotube type and weight fraction of components—on the mechanical properties was investigated. Samples were characterized via nano-indentation and DMA. The BGA composed of 22 wt% single-walled carbon nanotubes and 45 wt% ionic liquid exhibited the highest hardness, adhesion, viscosity, and elastic and storage moduli. This study revealed the important role of the carbon nanotube type on BGA adhesion. Samples made with multi-walled carbon nanotubes had the lowest adhesion, which is a required factor in applications such as microfluidics. (paper)

  15. Thermomechanical characterization of thiol-epoxy shape memory thermosets for mechanical actuators design

    Science.gov (United States)

    Belmonte, Alberto; Fernández-Francos, Xavier; De la Flor, Silvia

    2018-02-01

    In this paper, shape-memory "thiol-epoxy" polymers are synthesized and characterized as potential thermomechanical actuators. Their thermomechanical properties are investigated through dynamo mechanical and tensile analyses and related to their network structural properties by using "thiol" and "epoxy" compounds of different functionality and structure. Their mechanical properties (resistance at break, elongation limits and strain energy) are related to their shape-memory response under free-recovery conditions and partially-constrained conditions, thus, establishing the connection between network relaxation (free-recovery) with the work output capabilities (partially-constrained). Results show high mechanical performance, achieving high elongation at break values (up to 100%) and stress at break values (up to 50 MPa). The shape-memory experiments reveal strong dependence of the programming conditions and network structure on the recovery efficiency at free-conditions, whereas under partially-constrained conditions, the controlling factors are the mechanical limits at high temperature. Moreover, some recommendations to achieve the maximum work output efficiency for a given operational design of a thermomechanical actuator are deduced.

  16. Application of a hybrid modular acquisition system to the control of a suspended interferometer with electrostatic actuators

    Energy Technology Data Exchange (ETDEWEB)

    Acernese, F; Barone, F; Boiano, A; Rosa, R D; Garufi, F; Milano, L; Mosca, S; Persichetti, G; Romano, R [INFN - Sezione di Napoli, Complesso Universitario di Monte S. Angelo, via Cintia, 80126, Napoli (Italy); Perreca, A [University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom)], E-mail: fabrizio.barone@na.infn.it

    2008-07-15

    In this paper we describe the architecture and the performances of a hybrid modular acquisition and control system prototype developed for the implementation of distributed monitoring and control systems. The system, an alternative to the VME-UDP/IP based system, is based on a dual-channel 18-bit low noise ADC and 16-bit DAC module at 800 kHz, managed by an ALTERA FPGA. Experimental tests have demonstrated that this architecture allows the implementation of distributed control systems with delay time t < 30{mu}s, on single channel, using a standard laptop PC for the real-time computation. The system was used for the longitudinal control of the end mirror of a suspended Michelson Interferometer, performed through an electrostatic actuators, giving effective performances. The preliminary results are also reported.

  17. Analytical energy spectrum for hybrid mechanical systems

    International Nuclear Information System (INIS)

    Zhong, Honghua; Xie, Qiongtao; Lee, Chaohong; Guan, Xiwen; Gao, Kelin; Batchelor, Murray T

    2014-01-01

    We investigate the energy spectrum for hybrid mechanical systems described by non-parity-symmetric quantum Rabi models. A set of analytical solutions in terms of the confluent Heun functions and their analytical energy spectrum is obtained. The analytical energy spectrum includes regular and exceptional parts, which are both confirmed by direct numerical simulation. The regular part is determined by the zeros of the Wronskian for a pair of analytical solutions. The exceptional part is relevant to the isolated exact solutions and its energy eigenvalues are obtained by analyzing the truncation conditions for the confluent Heun functions. By analyzing the energy eigenvalues for exceptional points, we obtain the analytical conditions for the energy-level crossings, which correspond to two-fold energy degeneracy. (paper)

  18. Distributed power and control actuation in the thoracic mechanics of a robotic insect

    International Nuclear Information System (INIS)

    Finio, Benjamin M; Wood, Robert J

    2010-01-01

    Recent advances in the understanding of biological flight have inspired roboticists to create flapping-wing vehicles on the scale of insects and small birds. While our understanding of the wing kinematics, flight musculature and neuromotor control systems of insects has expanded, in practice it has proven quite difficult to construct an at-scale mechanical device capable of similar flight performance. One of the key challenges is the development of an effective and efficient transmission mechanism to control wing motions. Here we present multiple insect-scale robotic thorax designs capable of producing asymmetric wing kinematics similar to those observed in nature and utilized by dipteran insects to maneuver. Inspired by the thoracic mechanics of dipteran insects, which entail a morphological separation of power and control muscles, these designs show that such distributed actuation can also modulate wing motion in a robotic design.

  19. Distributed power and control actuation in the thoracic mechanics of a robotic insect.

    Science.gov (United States)

    Finio, Benjamin M; Wood, Robert J

    2010-12-01

    Recent advances in the understanding of biological flight have inspired roboticists to create flapping-wing vehicles on the scale of insects and small birds. While our understanding of the wing kinematics, flight musculature and neuromotor control systems of insects has expanded, in practice it has proven quite difficult to construct an at-scale mechanical device capable of similar flight performance. One of the key challenges is the development of an effective and efficient transmission mechanism to control wing motions. Here we present multiple insect-scale robotic thorax designs capable of producing asymmetric wing kinematics similar to those observed in nature and utilized by dipteran insects to maneuver. Inspired by the thoracic mechanics of dipteran insects, which entail a morphological separation of power and control muscles, these designs show that such distributed actuation can also modulate wing motion in a robotic design.

  20. Novel Additive Manufacturing Pneumatic Actuators and Mechanisms for Food Handling Grippers

    Directory of Open Access Journals (Sweden)

    Carlos Blanes

    2014-07-01

    Full Text Available Conventional pneumatic grippers are widely used in industrial pick and place robot processes for rigid objects. They are simple, robust and fast, but their design, motion and features are limited, and they do not fulfil the final purpose. Food products have a wide variety of shapes and textures and are susceptible to damaged. Robot grippers for food handling should adapt to this wide range of dimensions and must be fast, cheap, reasonably reliable, and with cheap and reasonable maintenance costs. They should not damage the product and must meet hygienic conditions. The additive manufacturing (AM process is able to manufacture parts without significant restrictions, and is Polyamide approved as food contact material by FDA. This paper presents that, taking the best of plastic flexibility, AM allows the implementation of novel actuators, original compliant mechanisms and practical grippers that are cheap, light, fast, small and easily adaptable to specific food products. However, if they are not carefully designed, the results can present problems, such as permanent deformations, low deformation limits, and low operation speed. We present possible solutions for the use of AM to design proper robot grippers for food handling. Some successful results, such as AM actuators based on deformable air chambers, AM compliant mechanisms, and grippers developed in a single part will be introduced and discussed.

  1. Experimental Data Collection and Modeling for Nominal and Fault Conditions on Electro-Mechanical Actuators

    Data.gov (United States)

    National Aeronautics and Space Administration — Being relatively new to the field, electromechanical actuators in aerospace applications lack the knowledge base compared to ones accumulated for the other actuator...

  2. Two-stage actuation system using DC motors and piezoelectric actuators for controllable industrial and automotive brakes and clutches

    Science.gov (United States)

    Neelakantan, Vijay A.; Washington, Gregory N.; Bucknor, Norman K.

    2005-05-01

    High bandwidth actuation systems that are capable of simultaneously producing relatively large forces and displacements are required for use in automobiles and other industrial applications. Conventional hydraulic actuation mechanisms used in automotive brakes and clutches are complex, inefficient and have poor control robustness. These lead to reduced fuel economy, controllability issues and other disadvantages. This paper involves the design, development, testing and control of a two-stage hybrid actuation mechanism by combining classical actuators like DC motors and advanced smart material actuators like piezoelectric actuators. The paper also discusses the development of a robust control methodology using the Internal Model Control (IMC) principle and emphasizes the robustness property of this control methodology by comparing and studying simulation and experimental results.

  3. Pointwise Stabilization of a Hybrid System and Optimal Location of Actuator

    International Nuclear Information System (INIS)

    Ammari, Kais; Saidi, Abdelkader

    2007-01-01

    We consider a pointwise stabilization problem for a model arising in the control of noise. We prove that we have exponential stability for the low frequencies but not for the high frequencies. Thus, we give an explicit polynomial decay estimation at high frequencies that is valid for regular initial data while clarifying that the behavior of the constant which intervenes in this estimation there, functions as the frequency of cut. We propose a numerical approximation of the model and study numerically the best location of the actuator at low frequencies

  4. Crane system with remote actuation mechanism for use in argon compartment in ACPF hot cell

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Kwang, E-mail: leejk@kaeri.re.kr; Park, Byung-Suk; Yu, Seung-Nam; Kim, Kiho; Cho, Il-je

    2016-10-15

    Highlights: • Novel crane system with a remote actuation mechanism for feasible maintenance under limited space conditions is proposed. • Linear drive systems are implemented for accurate positioning. • Modular design concepts for easy maintenance are introduced. • The motion controller and the off-the-shelf camera controller are integrated to provide more efficient operation. - Abstract: The Advanced spent fuel Conditioning Process Facility (ACPF) at the Korea Atomic Energy Research Institute (KAERI) has recently been successfully renovated. One of the highlights of this renovation project was the installation of a small argon compartment within the atmospheric hot cell of the facility. Even though a crane system was considered necessary for the remote handling of the processing equipment inside the argon compartment, no suitable commercial cranes were available. This was because a limited amount of space had been reserved for the installation of the crane. Moreover, a master-slave manipulator (MSM), the only available means of maintenance of the crane, was unable to reach it in the limited workspace. To address the difficulties in the design of this crane, in this study, a remote actuation mechanism is devised where the mechanical and electrical parts of the crane system are separated, positioned far away from each other, and connected through power transmission shafts. This approach has two main advantages. First, the electrical parts can be placed inside the workspace of the MSM, hence allowing for remote maintenance. Second, the space occupied by the electrical parts and their cables, which are separate from the crane in the proposed design, can be considered and exploited in designing the mechanical parts of the crane. This enables the construction of a short, special crane in order to maximize the workspace. Furthermore, the mechanical parts for the MSM located outside the workspace are designed to possess a high safety margin to ensure durability

  5. High-performance hybrid (electrostatic double-layer and faradaic capacitor-based) polymer actuators incorporating nickel oxide and vapor-grown carbon nanofibers.

    Science.gov (United States)

    Terasawa, Naohiro; Asaka, Kinji

    2014-12-02

    The electrochemical and electromechanical properties of polymeric actuators prepared using nickel peroxide hydrate (NiO2·xH2O) or nickel peroxide anhydride (NiO2)/vapor-grown carbon nanofibers (VGCF)/ionic liquid (IL) electrodes were compared with actuators prepared using solely VGCFs or single-walled carbon nanotubes (SWCNTs) and an IL. The electrode in these actuator systems is equivalent to an electrochemical capacitor (EC) exhibiting both electrostatic double-layer capacitor (EDLC)- and faradaic capacitor (FC)-like behaviors. The capacitance of the metal oxide (NiO2·xH2O or NiO2)/VGCF/IL electrode is primarily attributable to the EDLC mechanism such that, at low frequencies, the strains exhibited by the NiO2·xH2O/VGCF/IL and NiO2/VGCF/IL actuators primarily result from the FC mechanism. The VGCFs in the NiO2·xH2O/VGCF/IL and NiO2/VGCF/IL actuators strengthen the EDLC mechanism and increase the electroconductivity of the devices. The mechanism underlying the functioning of the NiO2·xH2O/VGCF/IL actuator in which NiO2·xH2O/VGCF = 1.0 was found to be different from that of the devices produced using solely VGCFs or SWCNTs, which exhibited only the EDLC mechanism. In addition, it was found that both NiO2 and VGCFs are essential with regard to producing actuators that are capable of exhibiting strain levels greater than those of SWCNT-based polymer actuators and are thus suitable for practical applications. Furthermore, the frequency dependence of the displacement responses of the NiO2·xH2O/VGCF and NiO2/VGCF polymer actuators were successfully simulated using a double-layer charging kinetic model. This model, which accounted for the oxidization and reduction reactions of the metal oxide, can also be applied to SWCNT-based actuators. The results of electromechanical response simulations for the NiO2·xH2O/VGCF and NiO2/VGCF actuators predicted the strains at low frequencies as well as the time constants of the devices, confirming that the model is applicable

  6. The Variable Stiffness Actuator vsaUT-II: Mechanical Design, Modeling, and Identification

    NARCIS (Netherlands)

    Groothuis, Stefan; Rusticelli, Giacomo; Zucchelli, Andrea; Stramigioli, Stefano; Carloni, Raffaella

    In this paper, the rotational variable stiffness actuator vsaUT-II is presented. This actuation system is characterized by the property that the apparent stiffness at the actuator output can be varied independently from its position. This behavior is realized by implementing a variable transmission

  7. Investigation of Gas Piston Actuated Opening-Closing Trunk Lid Mechanisms Used in Passenger Cars

    Directory of Open Access Journals (Sweden)

    Ahmet YILDIZ

    2015-05-01

    Full Text Available In this study, the gas piston actuated opening-closing trunk lid mechanisms used in passenger cars are investigated theoretically and experimentally. First, the position analysis of the mechanism which is a four-bar linkage has been carried out. Then the quasi-static analyzes according to the principle of virtual work have been made, and so the hand force, one of the most important parameters in terms of ergonomics, required for opening and closing the trunk lid has been calculated. In order to verify this developed model, the hand force has been determined also experimentally, performing the physical tests on an existing vehicle at Turkish Automobile Factory Inc. (TOFAŞ. Eventually, it is observed that the results obtained from mathematical model and the experimental measurements are compatible each other. This established model will provide convenience for manufacturers to determine the hand force for different model of vehicles. 

  8. A Novel Hybrid Actuator Driven Magnetically in the Bi-Cell PEM Fuel Cell Stack

    Directory of Open Access Journals (Sweden)

    Hsiaokang Ma

    2017-10-01

    Full Text Available This study develops an air breathing pump driven by a piezoelectric actuator for a proton exchange membrane fuel cell (PEMFC stack. Permanent magnets are combined with a piezoelectric actuator to drive three air breathing pumps using magnetic force. This design enables the pump to provide a sufficient amount of air simultaneously to six cathode flow field plates in a stack of three “bi-cell PZTmag–PEMFCs”. When both the PZTmag and the PDMSmag had a magnet with a 6-mm diameter and 1-mm thickness, a maximum amplitude of 87 μm was generated at 0.03 W of power under operating conditions of 70 Hz and 40 V. In computational fluid dynamics (CFD, when the nozzle and the diffuser of an air breathing pump have an aspect ratio of 13.13, air flow distributes uniformly inside the pump, thus allowing for uniform transmission of oxygen to the membrane electrode assembly. This aspect ratio was applied to the bi-cell PZTmag–PEMFC stack and yielded a maximum net power flux of 0.1925 W·cm−2, 20% higher than that reported in a previous study (Ma, 2013, with 68% and 76% less volume and weight, respectively.

  9. Electrochemical fabrication and modelling of mechanical behavior of a tri-layer polymer actuator

    International Nuclear Information System (INIS)

    Kaynak, Akif; Yang Chunhui; Lim, Yang C.; Kouzani, Abbas

    2011-01-01

    Stability and performance of electrochemically synthesized tri-layer polypyrrole based actuators were reported. Concentrations were optimized as 0.05 M pyrrole and 0.05 M tetrabutylammonium hexaflurophosphate in propylene carbonate (PC). The force output of the actuators ranged from 0.2 to 0.4 mN. Cyclic deflection tests on PC based actuators for a duration of 3 h indicated that the displacement decreased by 60%. However, actuation could be regenerated by immersing the actuator into the electrolyte solution. Surface resistivity measurements on the actuators prior to and after 3 h continuous deflection did not show any significant change in the resistivity of the PPy layer. A triple-layer model of the polymer actuator was developed based on the classic bending beam theory by considering strain continuity between PPy and PVDF. Results predicted by the model were in good agreement with the experimental data.

  10. Mechanical design of EFW Exo II: A hybrid exoskeleton for elbow-forearm-wrist rehabilitation.

    Science.gov (United States)

    Bian, Hui; Chen, Ziye; Wang, Hao; Zhao, Tieshi

    2017-07-01

    The use of rehabilitation exoskeleton has become an important means for the treatment of stroke patients. A hybrid exoskeleton named EFW Exo II is developed for the motor function rehabilitation of elbow, forearm and wrist. The EFW Exo II is based on a parallel 2-URR/RRS mechanism and a serial R mechanism. It could fit both left and right arms for the symmetrical and open structure, and the distance between the elbow and wrist could automatically adjust for different forearm length. Details of the mechanical design are introduced. Brushless DC servo motors with planetary gear reducer are used as the actuators of the exoskeleton. Gear drive and belt drive are used for power transmission. A three dimensional force sensor is mounted in the handle to regulate the interaction between the exoskeleton and patient. The EFW Exo II can realize rehabilitation exercise for each joint and the ranges of motion meet the rehabilitation demands of daily living.

  11. A novel vibration assisted polishing device based on the flexural mechanism driven by the piezoelectric actuators

    Directory of Open Access Journals (Sweden)

    Guilian Wang

    2018-01-01

    Full Text Available The vibration assisted polishing has widely application fields because of higher machining frequency and better polishing quality, especially the polishing with the non-resonant mode that is regarded as a kind of promising polishing method. This paper reports a novel vibration assisted polishing device, consisting of the flexible hinge mechanism driven by the piezoelectric actuators, which is suitable for polishing planes or curve surfaces with slow curvature. Firstly, the generation methods of vibration trajectory are investigated for the same frequency and different frequency signals’ inputs, respectively, and then the types of elliptic and Lissajous’s vibration trajectories are generated respectively. Secondly, a flexural mechanism consisting of the right circular flexible hinges and the leaf springs is developed to produce two-dimensional vibration trajectory. Statics and dynamics investigating of this flexible mechanism are finished in detail. The analytical models about input and output compliances of the flexural mechanism are established according to the matrix-based compliance modeling, and the dynamic model of the flexural mechanism based on the Euler-Lagrange equation is also presented. The finite element model of the flexural mechanism was established to carry out the numerical simulation in order to testify the rationality of device design. Finally, the polishing experiment is carried out to prove the effectiveness of the vibration device. The experimental results show that this novel vibration assisted polishing device developed in this study can remove more effectively the cutting marks left by last process and obviously reduce the workpiece surface roughness.

  12. Dynamics and control of hybrid mechanical systems

    NARCIS (Netherlands)

    Leonov, G.A.; Nijmeijer, H.; Pogromski, A.Y.; Fradkov, A.L.

    2010-01-01

    The papers in this edited volume aim to provide a better understanding of the dynamics and control of a large class of hybrid dynamical systems that are described by different models in different state space domains. They not only cover important aspects and tools for hybrid systems analysis and

  13. Numerical study of nozzle design for the hybrid synthetic jet actuator

    Czech Academy of Sciences Publication Activity Database

    Hsu, S.-S.; Chou, Y.-J.; Trávníček, Zdeněk; Lin, C.-F.; Wang, A. B.; Yen, R.H.

    2015-01-01

    Roč. 232, August (2015), s. 172-182 ISSN 0924-4247 R&D Projects: GA ČR GA14-08888S Institutional support: RVO:61388998 Keywords : synthetic jet * hybrid synthetic jet * numerical simulation Subject RIV: JU - Aeronautics, Aerodynamics, Aircrafts Impact factor: 2.201, year: 2015 http://www.sciencedirect.com/science/article/pii/S0924424715300091

  14. An experimental evaluation of the fully coupled hysteretic electro-mechanical behaviour of piezoelectric actuators

    Energy Technology Data Exchange (ETDEWEB)

    Butcher, Mark [Department of Engineering, CERN, 1211 Geneva (Switzerland); Davino, Daniele, E-mail: davino@unisannio.it [Department of Engineering, University of Sannio, Benevento (Italy); Giustiniani, Alessandro; Masi, Alessandro [Department of Engineering, CERN, 1211 Geneva (Switzerland)

    2016-04-01

    Piezoelectrics are the most commonly used of the multifunctional smart materials in industrial applications, because of their relatively low cost and ease of use in electric and electronic oriented applications. Nevertheless, while datasheets usually give just small signal quasi-static parameters, their full potential can only be exploited only if a full characterization is available because the maximum stroke or the higher piezo coupling coefficients are available at different electro-mechanical biases, where often small signal analysis is not valid. In this paper a method to get the quasi-static fully coupled characterization is presented. The method is tested on a commercial piezo actuator but can be extended to similar devices.

  15. submitter An experimental evaluation of the fully coupled hysteretic electro-mechanical behaviour of piezoelectric actuators

    CERN Document Server

    Butcher, Mark; Giustiniani, Alessandro; Masi, Alessandro

    2016-01-01

    Piezoelectrics are the most commonly used of the multifunctional smart materials in industrial applications, because of their relatively low cost and ease of use in electric and electronic oriented applications. Nevertheless, while datasheets usually give just small signal quasi-static parameters, their full potential can only be exploited only if a full characterization is available because the maximum stroke or the higher piezo coupling coefficients are available at different electro-mechanical biases, where often small signal analysis is not valid. In this paper a method to get the quasi-static fully coupled characterization is presented. The method is tested on a commercial piezo actuator but can be extended to similar devices.

  16. Impinging jet-based fluidic diodes for hybrid synthetic jet actuators

    Czech Academy of Sciences Publication Activity Database

    Kordík, Jozef; Broučková, Zuzana; Trávníček, Zdeněk

    2015-01-01

    Roč. 18, č. 3 (2015), s. 449-458 ISSN 1343-8875 R&D Projects: GA ČR GPP101/12/P556 Institutional support: RVO:61388998 Keywords : synthetic jet * hybrid synthetic jet * volumetric efficiency Subject RIV: BK - Fluid Dynamics Impact factor: 0.720, year: 2015 http://link.springer.com/article/10.1007%2Fs12650-014-0251-0

  17. Mechanisms of Surface-Mediated DNA Hybridization

    Science.gov (United States)

    2015-01-01

    Single-molecule total internal reflection fluorescence microscopy was employed in conjunction with resonance energy transfer (RET) to observe the dynamic behavior of donor-labeled ssDNA at the interface between aqueous solution and a solid surface decorated with complementary acceptor-labeled ssDNA. At least 100 000 molecular trajectories were determined for both complementary strands and negative control ssDNA. RET was used to identify trajectory segments corresponding to the hybridized state. The vast majority of molecules from solution adsorbed nonspecifically to the surface, where a brief two-dimensional search was performed with a 7% chance of hybridization. Successful hybridization events occurred with a characteristic search time of ∼0.1 s, and unsuccessful searches resulted in desorption from the surface, ultimately repeating the adsorption and search process. Hybridization was reversible, and two distinct modes of melting (i.e., dehybridization) were observed, corresponding to long-lived (∼15 s) and short-lived (∼1.4 s) hybridized time intervals. A strand that melted back onto the surface could rehybridize after a brief search or desorb from the interface. These mechanistic observations provide guidance for technologies that involve DNA interactions in the near-surface region, suggesting a need to design surfaces that both enhance the complex multidimensional search process and stabilize the hybridized state. PMID:24708278

  18. Experimental investigations of the large deflection capabilities of a compliant parallel mechanism actuated by shape memory alloy wires

    International Nuclear Information System (INIS)

    Sreekumar, M; Nagarajan, T; Singaperumal, M

    2008-01-01

    This experimental study investigates the coupled effect of the force developed by the shape memory alloy (SMA) actuators and the force required for the large deflection of an elastica member in a compliant parallel mechanism. The compliant mechanism developed in house consists of a moving platform mounted on a superelastic pillar and three SMA wire actuators to manipulate the platform. A three-axis MEMS accelerometer has been mounted on the moving platform to measure its tilt angle. Three miniature force sensors have been designed and fabricated out of cantilever beams, each mounted with a pair of strain gauges, to measure the force developed by the respective actuators. The force sensors are highly sensitive and cost effective compared to commercially available miniature force sensors. Calibration of the force sensors has been accomplished with known weights, and for the three-axis MEMS accelerometer a rotary base has been considered which is usually used in optical applications. The calibration curves obtained, with R-squared values between 0.9997 and 1.0, show that both the tilt and force sensors considered are most appropriate for the respective applications. The mechanism fixed with the sensors and the drivers for the SMA actuators is integrated with a National Instrument's data acquisition system. The experimental results have been compared with the analytical results and it was found that the relative error is less than 2%. This is a preliminary study in the development of a mechanism for eye prosthesis and similar applications

  19. Integrated, Reactor Relevant Solutions for Lower Hybrid Range of Frequencies Actuators

    Science.gov (United States)

    Shiraiwa, S.; Bonoli, P. T.; Lin, Y.; Wallace, G. M.; Wukitch, S. J.

    2017-10-01

    RF (radiofrequency) actuators with high system efficiency (wall-plug to plasma) and ability for continuous operation have long be recognized as essential tools for realizing a steady state tokamak. A number of physics and technological challenges to utilization remain including current drive efficiency and location, efficient coupling, and impurity contamination. In a reactor environment, plasma material interaction (PMI) issues associated with coupling structures are similar to the first wall and have been identified as a potential show-stopper. High field side (HFS) launch of LHRF power represents an integrated solution that both improves core wave physics and mitigates PMI/coupling issues. For HFS LHRF, wave penetration is vastly improves because wave accessibility scales as 1/B allowing for launching the wave at lower n|| (parallel refractive index). The lower n|| penetrate to higher electron temperature resulting in higher current drive efficiency (1/n||2). HFS RF launch also provides for a means to dramatically improve launcher robustness in a reactor environment. On the HFS, the SOL is quiescent; local density profile is steep and controlled through magnetic shape; fast particle, neutron, turbulent heat and particle fluxes are eliminated or minim Work supported by the U.S. DoE, Office of Science, Office of Fusion Energy Sciences, User Facility Alcator C-Mod under DE-FC02-99ER54512 and US DoE Contract No. DE-FC02-01ER54648 under a Scientific Discovery through Advanced Computing Initiative.

  20. A new hybrid observer based rotor imbalance vibration control via passive autobalancer and active bearing actuation

    Science.gov (United States)

    Jung, DaeYi; DeSmidt, Hans

    2018-02-01

    Many researchers have explored the use of active bearings, such as non-contact Active Magnetic Bearings (AMB), to control imbalance vibration in rotor systems. Meanwhile, the advantages of a passive Auto-balancer device (ABD) eliminating the imbalance effect of rotor without using other active means have been recently studied. This paper develops a new hybrid imbalance vibration control approach for an ABD-rotor system supported by a normal passive bearing in augmented with an AMB to enhance the balancing and vibration isolation capabilities. Essentially, an ABD consists of several freely moving eccentric balancing masses mounted on the rotor, which, at supercritical operating speeds, act to cancel the rotor's imbalance at steady-state. However, due to the inherent nonlinearity of the ABD, the potential for other, non-synchronous limit-cycle behavior exists resulting in increased rotor vibration. To address this, the algorithm of proposed hybrid control is designed to guarantee globally asymptotic stability of the synchronous balanced condition. This algorithm also incorporates with a "Luenberger-like" observer that continuously estimates the states of a balancer ball circulating around within ABD. In particular, it is shown that the balanced equilibrium can be made globally attractive under the hybrid control strategy, and that the control power levels of AMB are significantly reduced via the addition of the ABD because the control is designed such that it is only switched on for the abnormal operation of ABD and will be disengaged otherwise. Moreover, unlike other imbalance vibration control applications based upon ABD such as rotor speed regulator [21,22], this approach enables the controller to achieve the desirable performance without altering rotor speed once the rotor initially reaches the target speed. These applications are relevant to limited power applications such as in satellite reaction wheels, flywheel energy storage batteries or CD-ROM application.

  1. An investigation of the mechanical behavior of initially curved microplates under electrostatic actuation

    KAUST Repository

    Saghir, Shahid

    2018-03-28

    In this article, we investigate the mechanical behavior of initially curved microplates under electrostatic actuation. Microplates are essential components of many Micro-Electro-Mechanical System devices; however, they commonly undergo an initial curvature imperfection, due to the microfabrication process. Initial curvature imperfection significantly affects the mechanical behavior of microplates. In this work, we derive a dynamic analogue of the von Kármán governing equation for such plates. These equations are then used to develop a reduced order model based on the Galerkin procedure to simulate the static and dynamic behavior of the microplate. Two profiles of initial curvature commonly encountered in microfabricated structures are considered, where one assumes a variation in shape along one dimension of the plate only (cylindrical bending shape) while the other assumes a variation in shape along both dimensions of the plate. Their effects on both the static and dynamic responses of the microplates are examined and compared. We validate the reduced order model by comparing the calculated static behavior and the fundamental natural frequency with those computed by a finite element model over a range of the initial plate rise. The static behavior of the microplate is investigated when varying the DC voltage. Then, the dynamic behavior of the microplate is examined under the application of a harmonic AC voltage superimposed to a DC voltage.

  2. A jellyfish-inspired jet propulsion robot actuated by an iris mechanism

    International Nuclear Information System (INIS)

    Marut, Kenneth; Stewart, Colin; Michael, Tyler; Villanueva, Alex; Priya, Shashank

    2013-01-01

    A jellyfish-inspired jet propulsion robot (JetPRo) is designed, fabricated, and characterized with the objective of creating a fast-swimming uncrewed undersea vehicle. JetPRo measures 7.9 cm in height, 5.7 cm in diameter and is designed to mimic the proficient jetting propulsion mechanism used by the hydromedusa Sarsia tubulosa, which measures approximately 1 cm in diameter. In order to achieve the uniform-bell contraction used by S. tubulosa, we develop a novel circumferential actuation technique based on a mechanical iris diaphragm. When triggered, this mechanism induces a volumetric change of a deformable silicone cavity to expel a jet of fluid and produces positive thrust. A theoretical jetting model is used to optimize JetPRo’s gait for maximum steady-state swimming velocity, a result achieved by minimizing the timing between the contraction and relaxation phases. We validate this finding empirically and quantify the swimming performance of the robot using video tracking and time resolved digital particle image velocimetry. JetPRo was able to produce discrete vortex rings shed before pinch off and swim upwards with a maximum steady-state velocity of 11.6 cm s −1 , outperforming current state-of-the-art robotic jellyfish in velocity as well as diameter-normalized velocity. (paper)

  3. Investigation on the Mechanical and Electrical Behavior of a Tuning Fork-Shaped Ionic Polymer Metal Composite Actuator with a Continuous Water Supply Mechanism.

    Science.gov (United States)

    Feng, Guo-Hua; Huang, Wei-Lun

    2016-03-25

    This paper presents an innovative tuning fork-shaped ionic polymer metal composite (IPMC) actuator. With an integrated soft strain gauge and water supply mechanism (WSM), the surface strain of the actuator can be sensed in situ, and providing a continuous water supply maintains the water content inside the IPMC for long-term operation in air. The actuator was fabricated using a micromachining technique and plated with a nickel electrode. The device performance was experimentally characterized and compared with an actuator without a WSM. A large displacement of 1.5 mm was achieved for a 6 mm-long prong with 7-V dc actuation applied for 30 s. The measured current was analyzed using an electrochemical model. The results revealed that the faradaic current plays a crucial role during operation, particularly after 10 s. The measured strain confirms both the bending and axial strain generation during the open-and-close motion of the actuator prongs. Most of the water loss during device operation was due to evaporation rather than hydrolysis. The constructed WSM effectively maintained the water content inside the IPMC for long-term continuous operation.

  4. An experimental and analytical study on the feasibility of SMA spring driven actuation of an iris mechanism

    International Nuclear Information System (INIS)

    Rajan, Aravindh; Abouseada, Mostafa; Manghaipathy, Pavithra; Ozalp, Nesrin; Majid, Feras Abdul; Salem, Ayman; Srinivasa, Arun

    2016-01-01

    Highlights: • An iris mechanism proposed in response to fluctuations in solar energy. • Iris motion controlled with the use of Nickel–Titanium Shape Memory Alloy springs. • Variation of the force exerted by SMA spring w.r.t. temperature tested experimentally. • An analytical expression that relates the aperture area and crank rotation is given. • SMA springs showed promising actuation mechanism as a replacement to motor. - Abstract: Variation in incoming solar energy adversely affects the temperature inside a solar reactor and lowers its efficiency. Therefore, it is important to develop a mechanism that can maintain semi-constant temperatures inside the reactor from sunrise to sunset. In this paper, we present an iris mechanism that reduces or enlarges its circular opening with the use of Nickel–Titanium Shape Memory Alloy (SMA) springs. SMA springs possess memory of their shapes at certain temperatures. Hence, by controlling the temperature of the spring, it is possible to exert different forces that may then be transferred to the variable aperture mechanism. In this study, variation of the force exerted by an SMA spring with respect to temperature was experimentally tested and the viability of an SMA spring’s use in actuating an iris mechanism aperture was examined. In order to simulate conditions under fluctuating solar radiation, a 7 kW solar simulator was used in experiments at varying power levels. It was observed that SMA springs are promising as a replacement of the actuation mechanism driven by a motor.

  5. Maximising electro-mechanical response by minimising grain-scale strain heterogeneity in phase-change actuator ceramics

    DEFF Research Database (Denmark)

    Oddershede, Jette; Hossain, Mohammad Jahangir; Daniels, John E.

    2016-01-01

    Phase-change actuator ceramics directly couple electrical and mechanical energies through an electric-field-induced phase transformation. These materials are promising for the replacement of the most common electro-mechanical ceramic, lead zirconate titanate, which has environmental concerns. Here......, we show that by compositional modification, we reduce the grain-scale heterogeneity of the electro-mechanical response by 40%. In the materials investigated, this leads to an increase in the achievable electric-field-induced strain of the bulk ceramic of 45%. Compositions of (100-x)Bi0.5Na0.5TiO3-(x...... heterogeneity can be achieved by precise control of the lattice distortions and orientation distributions of the induced phases. The current results can be used to guide the design of next generation high-strain electro-mechanical ceramic actuator materials....

  6. Study on Mechanical and Physical Behaviour of Hybrid GFRP

    Directory of Open Access Journals (Sweden)

    Nor Bahiyah Baba

    2015-01-01

    Full Text Available The paper discusses the mechanical and physical behaviour of hybrid glass fibre reinforced plastic (GFRP. Hybrid GFRP was fabricated by three different types of glass fibre, namely, 3D, woven, and chopped, which were selected and combined with mixture of polyester resin and hardener. The hybrid GFRP was investigated by varying three parameters which were the composite volume fractions, hybrid GFRP arrangement, and single type fibre. The hybrid GFRP was fabricated by using open mould hand lay-up technique. Mechanical testing was conducted by tensile test for strength and stiffness whereas physical testing was performed using water absorption and hardness. These tests were carried out to determine the effect of mechanical and physical behaviour over the hybrid GFRP. The highest volume fraction of 0.5 gives the highest strength and stiffness of 73 MPa and 821 MPa, respectively. Varying hybrid fibre arrangement which is the arrangement of chopped-woven-3D-woven-chopped showed the best value in strength of 66.2 MPa. The stiffness is best at arrangement of woven-chopped-woven-chopped-woven at 690 MPa. This arrangement also showed the lowest water absorption of 4.5%. Comparing the single fibre type, woven had overtaken the others in terms of both mechanical and physical properties.

  7. A low cost and hybrid technology for integrating silicon sensors or actuators in polymer microfluidic systems

    International Nuclear Information System (INIS)

    Charlot, Samuel; Gué, Anne-Marie; Tasselli, Josiane; Marty, Antoine; Abgrall, Patrick; Estève, Daniel

    2008-01-01

    This paper describes a new technology permitting a hybrid integration of silicon chips in polymer (PDMS and SU8) microfluidic structures. This two-step technology starts with transferring the silicon device onto a rigid substrate (typically PCB) and planarizing it, and then it proceeds with stacking of the polymer-made fluidic network onto the device. The technology is low cost, based on screen printing and lamination, can be applied to treat large surface areas, and is compatible with standard photolithography and vacuum based approaches. We show, as an example, the integration of a thermal sensor inside channels made of PDMS or SU8. The developed structures had no fluid leaks at the Si/polymer interfaces and the electrical circuit was perfectly tightproof. (note)

  8. Hybrid carbon incentive mechanisms and political acceptability

    International Nuclear Information System (INIS)

    Vollebergh, H.R.J.; De Vries, J.L.; Koutstaal, P.R.

    1997-01-01

    In this paper it is analyzed how hybrid systems of carbon taxes and tradeable permits optimize some conflicting dimensions of political acceptability related to the design of these instruments. Pure systems like taxes without exemptions or auctioned tradeable permits cause problems for political acceptability in open economies due to high overall costs (abatement cost plus payments on the tax or auctions) for current polluters. Unfortunately, pure systems based on grandfathering of emission rights across the board do not provide a feasible alternative because of monitoring and enforcement problems. In contrast, consciously designed hybrid systems employ grandfathering of emission rights together with either carbon taxes or auctioned carbon permits in order to overcome acceptability problems of pure systems, while leaving incentives to reduce emissions at the margin untouched. Moreover, monitoring and enforcement costs of the hybrid systems are less due to the lower number of participating agents compared with the pure systems, while opportunities for cost- or burden-sharing exist as well. 3 figs., 4 tabs., 23 refs

  9. Mechanically-competent and cytocompatible polycaprolactone-borophosphosilicate hybrid biomaterials.

    Science.gov (United States)

    Mondal, Dibakar; Dixon, S Jeffrey; Mequanint, Kibret; Rizkalla, Amin S

    2017-11-01

    Organic-inorganic class II hybrid materials have domain sizes at the molecular level and chemical bonding between the organic and inorganic phases. We have previously reported the synthesis of class II hybrid biomaterials from alkoxysilane-functionalized polycaprolactone (PCL) and borophosphosilicate (B 2 O 3 -P 2 O 5 -SiO 2 ) glass (BPSG) through a non-aqueous sol-gel process. In the present study, the mechanical properties and degradability of these PCL/BPSG hybrid biomaterials were studied and compared to those of their conventional composite counterparts. The compressive strength, modulus and toughness of the hybrid biomaterials were significantly greater compared to the conventional composites, likely due to the covalent bonding between the organic and inorganic phases. A hybrid biomaterial (50wt% PCL and 50wt% BPSG) exhibited compressive strength, modulus and toughness values of 32.2 ± 3.5MPa, 573 ± 85MPa and 1.54 ± 0.03MPa, respectively; whereas the values for composite of similar composition were 18.8 ± 1.6MPa, 275 ± 28MPa and 0.76 ± 0.03MPa, respectively. Degradation in phosphate-buffered saline was slower for hybrid biomaterials compared to their composite counterparts. Thus, these hybrid materials possess superior mechanical properties and more controlled degradation characteristics compared to their corresponding conventional composites. To assess in vitro cytocompatibility, MC3T3-E1 pre-osteoblastic cells were seeded onto the surfaces of hybrid biomaterials and polycaprolactone (control). Compared to polycaprolactone, cells on the hybrid material displayed enhanced spreading, focal adhesion formation, and cell number, consistent with excellent cytocompatibility. Thus, based on their mechanical properties, degradability and cytocompatibility, these novel biomaterials have potential for use as scaffolds in bone tissue engineering and related applications. Copyright © 2017. Published by Elsevier Ltd.

  10. Study on Mechanical Properties of Hybrid Fiber Reinforced Concrete

    Science.gov (United States)

    He, Dongqing; Wu, Min; Jie, Pengyu

    2017-12-01

    Several common high elastic modulus fibers (steel fibers, basalt fibers, polyvinyl alcohol fibers) and low elastic modulus fibers (polypropylene fiber) are incorporated into the concrete, and its cube compressive strength, splitting tensile strength and flexural strength are studied. The test result and analysis demonstrate that single fiber and hybrid fiber will improve the integrity of the concrete at failure. The mechanical properties of hybrid steel fiber-polypropylene fiber reinforced concrete are excellent, and the cube compressive strength, splitting tensile strength and flexural strength respectively increase than plain concrete by 6.4%, 3.7%, 11.4%. Doped single basalt fiber or polypropylene fiber and basalt fibers hybrid has little effect on the mechanical properties of concrete. Polyvinyl alcohol fiber and polypropylene fiber hybrid exhibit ‘negative confounding effect’ on concrete, its splitting tensile and flexural strength respectively are reduced by 17.8% and 12.9% than the single-doped polyvinyl alcohol fiber concrete.

  11. A membrane actuator based on an ionic polymer network and carbon nanotubes: the synergy of ionic transport and mechanical properties

    International Nuclear Information System (INIS)

    Dai, Chi-An; Hsiao, Chih-Chun; Weng, Shih-Chun; Kao, An-Cheng; Liu, Chien-Pan; Tsai, Wei-Bor; Chen, Wen-Shiang; Liu, Wei-Ming; Shih, Wen-Pin; Ma, Chien-Ching

    2009-01-01

    There is a growing interest in the development of ionic polymer–metal composites (IPMC) as sensors and actuators for biomedical applications due to their large deformation under low driving voltage. In this study, we employed poly(vinyl alcohol)/poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PVA/PAMPS) blend membranes as semi-interpenetrating polymer networks for ion exchange in IPMC construction. To improve the mechanical and electrical properties of the IPMC, multi-walled carbon nanotubes (MWNT) were added into PVA/PAMPS membranes. The actuator performance of the membranes was measured as a function of their water uptake, ion exchange capacity, ionic conductivity and the amount of MWNT in the membrane. The dispersion quality of the modified MWNT in the PVA/PAMPS membrane was measured using transmission electron microscopy. The cantilever-type IPMC actuator bends under applied voltage and its bending angle and the generative tip force were measured. Under an applied voltage, IPMC with ∼1 wt% MWNT showed the largest deflection and generated the largest blocking tip force compared with those of IPMC with other various amounts of MWNT. These results show that a small addition of MWNT can optimize the actuation performance of IPMC. The result indicates that IPMC with MWNT shows potential for use as biomimetic artificial muscle

  12. Development of Component Mechanisms and Novel Actuation for Origami Inspired Designs

    Science.gov (United States)

    2016-11-17

    distribution unlimited. All structural components of the robot were fabricated with a 3D printer . The communication module, cooling fan, and battery for...wire actuator. The module has bi- stability so that it can maintain its shape without actuator force. Morphing Voxel Sheet Modular morphing...is the complexity of geometrical relationships between folding units requires complex pattern generation and folding sequence to build diverse 3D

  13. Mechanical behaviour of bending bucky-gel actuators and its representation

    International Nuclear Information System (INIS)

    Kruusamäe, Karl; Mukai, Ken; Sugino, Takushi; Asaka, Kinji

    2014-01-01

    Bucky-gel actuators are ionic electromechanically active materials that bend in response to a low-voltage excitation. While bending actuators may offer new approaches in engineering solutions, the characterization of bending poses many challenges in comparison to conventional rotary motion. It is often desired to reduce the bending behaviour to a single parameter, which may lead to the loss of accuracy in modelling. A high-speed laser profilometer is utilized to characterize the bending response of different bucky-gel actuators at their full length and to critically compare the applicability of existing representation tools for bending. The best analytical representation of the bending of a bucky-gel actuator is found to be in the form of a power function. It is also observed that, along the length of the actuator, sections closer to the electrical input clamp exhibit back-relaxation (a common drawback for bending ionic actuators) already when the far end of the bending strip is still in forward motion. (paper)

  14. Actuating mechanism and design of a cylindrical traveling wave ultrasonic motor using cantilever type composite transducer.

    Directory of Open Access Journals (Sweden)

    Yingxiang Liu

    Full Text Available BACKGROUND: Ultrasonic motors (USM are based on the concept of driving the rotor by a mechanical vibration excited on the stator via piezoelectric effect. USM exhibit merits such as simple structure, quick response, quiet operation, self-locking when power off, nonelectromagnetic radiation and higher position accuracy. PRINCIPAL FINDINGS: A cylindrical type traveling wave ultrasonic motor using cantilever type composite transducer was proposed in this paper. There are two cantilevers on the outside surface of cylinder, four longitudinal PZT ceramics are set between the cantilevers, and four bending PZT ceramics are set on each outside surface of cantilevers. Two degenerate flexural vibration modes spatially and temporally orthogonal to each other in the cylinder are excited by the composite transducer. In this new design, a single transducer can excite a flexural traveling wave in the cylinder. Thus, elliptical motions are achieved on the teeth. The actuating mechanism of proposed motor was analyzed. The stator was designed with FEM. The two vibration modes of stator were degenerated. Transient analysis was developed to gain the vibration characteristic of stator, and results indicate the motion trajectories of nodes on the teeth are nearly ellipses. CONCLUSIONS: The study results verify the feasibility of the proposed design. The wave excited in the cylinder isn't an ideal traveling wave, and the vibration amplitudes are inconsistent. The distortion of traveling wave is generated by the deformation of bending vibration mode of cylinder, which is caused by the coupling effect between the cylinder and transducer. Analysis results also prove that the objective motions of nodes on the teeth are three-dimensional vibrations. But, the vibration in axial direction is minute compared with the vibrations in circumferential and radial direction. The results of this paper can guide the development of this new type of motor.

  15. Actuating mechanism and design of a cylindrical traveling wave ultrasonic motor using cantilever type composite transducer.

    Science.gov (United States)

    Liu, Yingxiang; Chen, Weishan; Liu, Junkao; Shi, Shengjun

    2010-04-02

    Ultrasonic motors (USM) are based on the concept of driving the rotor by a mechanical vibration excited on the stator via piezoelectric effect. USM exhibit merits such as simple structure, quick response, quiet operation, self-locking when power off, nonelectromagnetic radiation and higher position accuracy. A cylindrical type traveling wave ultrasonic motor using cantilever type composite transducer was proposed in this paper. There are two cantilevers on the outside surface of cylinder, four longitudinal PZT ceramics are set between the cantilevers, and four bending PZT ceramics are set on each outside surface of cantilevers. Two degenerate flexural vibration modes spatially and temporally orthogonal to each other in the cylinder are excited by the composite transducer. In this new design, a single transducer can excite a flexural traveling wave in the cylinder. Thus, elliptical motions are achieved on the teeth. The actuating mechanism of proposed motor was analyzed. The stator was designed with FEM. The two vibration modes of stator were degenerated. Transient analysis was developed to gain the vibration characteristic of stator, and results indicate the motion trajectories of nodes on the teeth are nearly ellipses. The study results verify the feasibility of the proposed design. The wave excited in the cylinder isn't an ideal traveling wave, and the vibration amplitudes are inconsistent. The distortion of traveling wave is generated by the deformation of bending vibration mode of cylinder, which is caused by the coupling effect between the cylinder and transducer. Analysis results also prove that the objective motions of nodes on the teeth are three-dimensional vibrations. But, the vibration in axial direction is minute compared with the vibrations in circumferential and radial direction. The results of this paper can guide the development of this new type of motor.

  16. Sorption compressor/mechanical expander hybrid refrigeration

    Science.gov (United States)

    Jones, J. A.; Britcliffe, M.

    1987-01-01

    Experience with Deep Space Network (DSN) ground-based cryogenic refrigerators has proved the reliability of the basic two-stage Gifford-McMahon helium refrigerator. A very long life cryogenic refrigeration system appears possible by combining this expansion system or a turbo expansion system with a hydride sorption compressor in place of the usual motor driven piston compressor. To test the feasibility of this system, a commercial Gifford-McMahon refrigerator was tested using hydrogen gas as the working fluid. Although no attempt was made to optimize the system for hydrogen operation, the refrigerator developed 1.3 W at 30 K and 6.6 W at 60 K. The results of the test and of theoretical performances of the hybrid compressor coupled to these expansion systems are presented.

  17. Hybrid Hydrogen and Mechanical Distributed Energy Storage

    Directory of Open Access Journals (Sweden)

    Stefano Ubertini

    2017-12-01

    Full Text Available Effective energy storage technologies represent one of the key elements to solving the growing challenges of electrical energy supply of the 21st century. Several energy storage systems are available, from ones that are technologically mature to others still at a research stage. Each technology has its inherent limitations that make its use economically or practically feasible only for specific applications. The present paper aims at integrating hydrogen generation into compressed air energy storage systems to avoid natural gas combustion or thermal energy storage. A proper design of such a hybrid storage system could provide high roundtrip efficiencies together with enhanced flexibility thanks to the possibility of providing additional energy outputs (heat, cooling, and hydrogen as a fuel, in a distributed energy storage framework. Such a system could be directly connected to the power grid at the distribution level to reduce power and energy intermittence problems related to renewable energy generation. Similarly, it could be located close to the user (e.g., office buildings, commercial centers, industrial plants, hospitals, etc.. Finally, it could be integrated in decentralized energy generation systems to reduce the peak electricity demand charges and energy costs, to increase power generation efficiency, to enhance the security of electrical energy supply, and to facilitate the market penetration of small renewable energy systems. Different configurations have been investigated (simple hybrid storage system, regenerate system, multistage system demonstrating the compressed air and hydrogen storage systems effectiveness in improving energy source flexibility and efficiency, and possibly in reducing the costs of energy supply. Round-trip efficiency up to 65% can be easily reached. The analysis is conducted through a mixed theoretical-numerical approach, which allows the definition of the most relevant physical parameters affecting the system

  18. Modeling and optimization of a novel two-axis mirror-scanning mechanism driven by piezoelectric actuators

    International Nuclear Information System (INIS)

    Jing, Zijian; Xu, Minglong; Feng, Bo

    2015-01-01

    Mirror-scanning mechanisms are a key component in optical systems for diverse applications. However, the applications of existing piezoelectric scanners are limited due to their small angular travels. To overcome this problem, a novel two-axis mirror-scanning mechanism, which consists of a two-axis tip-tilt flexure mechanism and a set of piezoelectric actuators, is proposed in this paper. The focus of this research is on the design, theoretical modeling, and optimization of the piezoelectric-driven mechanism, with the goal of achieving large angular travels in a compact size. The design of the two-axis tip-tilt flexure mechanism is based on two nonuniform beams, which translate the limited linear output displacements of the piezoelectric actuators into large output angles. To exactly predict the angular travels, we built a voltage-angle model that characterizes the relationship between the input voltages to the piezoelectric actuators and the output angles of the piezoelectric-driven mechanism. Using this analytical model, the optimization is performed to improve the angular travels. A prototype of the mirror-scanning mechanism is fabricated based on the optimization results, and experiments are implemented to test the two-axis output angles. The experimental result shows that the angular travels of the scanner achieve more than 50 mrad, and the error between the analytical model and the experiment is about 11%. This error is much smaller than the error for the model built using the previous method because the influence of the stiffness of the mechanical structure on the deformation of the piezoelectric stack is considered in the voltage-angle model. (paper)

  19. Design and testing of botanical thermotropic actuator mechanisms in thermally adaptive building coverings

    Science.gov (United States)

    Barrett, Ronald M.; Barrett, Ronald P.; Barrett, Cassandra M.

    2017-09-01

    This paper lays out the inspiration, operational principles, analytical modeling and coupon testing of a new class of thermally adaptive building coverings. The fundamental driving concepts for these coverings are derived from various families of thermotropic plant structures. Certain plant cellular structures like those in Mimosa pudica (Sensitive Plant), Rhododendron leaves or Albizia julibrissin (Mimosa Tree), exhibit actuation physiology which depends on changes in cellular turgor pressures to generate motion. This form of cellular action via turgor pressure manipulation is an inspiration for a new field of thermally adaptive building coverings which use various forms of cellular foam to aid or enable actuation much like plant cells are used to move leaves. When exposed to high solar loading, the structures use the inherent actuation capability of pockets of air trapped in closed cell foam as actuators to curve plates upwards and outwards. When cold, these same structures curve back towards the building forming large convex pockets of dead air to insulate the building. This paper describes basic classical laminated plate theory models comparing theory and experiment of such coupons containing closed-cell foam actuators. The study concludes with a global description of the effectiveness of this class of thermally adaptive building coverings.

  20. The Pneumatic Actuators As Vertical Dynamic Load Simulators On Medium Weighted Wheel Suspension Mechanism

    Science.gov (United States)

    Ka'ka, Simon; Himran, Syukri; Renreng, Ilyas; Sutresman, Onny

    2018-02-01

    Almost all of road damage can be caused by dynamic loads of vehicles that fluctuate according to the type of vehicle that passes through. This study aims to calculate the vertical dynamic load of the vehicle actually occurs on road construction by the mechanism of vehicle wheel suspension. Pneumatic cylinders driven by pressurized air directly load the spring and shock absorber installed on the wheels of the vehicle. The load fluctuations of the medium weight categorized vehicles are determined by the regulation of the amount of pressurized air that enters into the pneumatic cylinder chamber, pushing the piston and connecting rods. The displacement that occurs during compression on the spring and shock absorber, is substituted into the equation of vehicle dynamic load while taking into account the spring stiffness constant, and the fluid or damper gas coefficient. The results show that the magnitude of the displacement when the compression force works has significant influences to the amount of vertical dynamic load of the vehicle that overlies the road construction. The presence of dynamic load of vehicles that fluctuates and repeats, also affects on the reduction of road ability to receive the load. Experimental results using pneumatic actuators instead of real dynamic vehicle loads illustrate the characteristics of the relationship between work pressure and dynamic load. If the working pressure of P2 (bar) is greater, the vertical dynamic load Ft (N) that overloads the road structure is also greater. The associate graphs show that the shock absorber has a greater ability to reduce dynamic load vertically that burden the road structure when compared with the ability of screw spring.

  1. Inspiration, simulation and design for smart robot manipulators from the sucker actuation mechanism of cephalopods.

    Science.gov (United States)

    Grasso, Frank W; Setlur, Pradeep

    2007-12-01

    Octopus arms house 200-300 independently controlled suckers that can alternately afford an octopus fine manipulation of small objects and produce high adhesion forces on virtually any non-porous surface. Octopuses use their suckers to grasp, rotate and reposition soft objects (e.g., octopus eggs) without damaging them and to provide strong, reversible adhesion forces to anchor the octopus to hard substrates (e.g., rock) during wave surge. The biological 'design' of the sucker system is understood to be divided anatomically into three functional groups: the infundibulum that produces a surface seal that conforms to arbitrary surface geometry; the acetabulum that generates negative pressures for adhesion; and the extrinsic muscles that allow adhered surfaces to be rotated relative to the arm. The effector underlying these abilities is the muscular hydrostat. Guided by sensory input, the thousands of muscle fibers within the muscular hydrostats of the sucker act in coordination to provide stiffness or force when and where needed. The mechanical malleability of octopus suckers, the interdigitated arrangement of their muscle fibers and the flexible interconnections of its parts make direct studies of their control challenging. We developed a dynamic simulator (ABSAMS) that models the general functioning of muscular hydrostat systems built from assemblies of biologically constrained muscular hydrostat models. We report here on simulation studies of octopus-inspired and artificial suckers implemented in this system. These simulations reproduce aspects of octopus sucker performance and squid tentacle extension. Simulations run with these models using parameters from man-made actuators and materials can serve as tools for designing soft robotic implementations of man-made artificial suckers and soft manipulators.

  2. A novel triple-actuating mechanism of an active air mount for vibration control of precision manufacturing machines: experimental work

    International Nuclear Information System (INIS)

    Kim, Hyung-Tae; Kim, Cheol-Ho; Choi, Seung-Bok; Moon, Seok-Jun; Song, Won-Gil

    2014-01-01

    With the goal of vibration control and isolation in a clean room, we propose a new type of air mount which consists of pneumatic, electromagnetic (EM), and magnetorheological (MR) actuators. The air mount is installed below a semiconductor manufacturing machine to reduce the adverse effects caused by unwanted vibration. The proposed mechanism integrates the forces in a parallel connection of the three actuators. The MR part is designed to operate in an air spring in which the EM part is installed. The control logic is developed with a classical method and a switching mode to avoid operational mismatch among the forces developed. Based on extended microprocessors, a portable, embedded controller is installed to execute both nonlinear logic and digital communication with the peripherals. The pneumatic forces constantly support the heavy weight of an upper structure and maintain the level of the air mount. The MR damper handles the transient response, while the EM controller reduces the resonance response, which is switched mutually with a threshold. Vibration is detected by laser displacement sensors which have submicron resolution. The impact test results of three tons load weight demonstrate practical feasibility by showing that the proposed triple-actuating mechanism can reduce the transient response as well as the resonance in the air mount, resulting in accurate motion of the semiconductor manufacturing machine. (technical note)

  3. Development of Cell Culture Microdevice Actuated by Piezoelectric Thin Films for Delivering Mechanical Vibratory Stimuli to Cells

    International Nuclear Information System (INIS)

    Yamada, Y; Umegaki, G; Kawashima, T; Nagai, M; Shibata, T; Masuzawa, T; Kimura, T; Kishida, A

    2012-01-01

    In order to realize a cell culture microdevice actuated by piezoelectric thin films for on-chip regulation of cell functions, this paper reported on a feasibility study by using the microdevice with KOH-etched cavities surrounded by four (111) sidewalls as microchambers in order to introduce cells to be cultured. As a result, the vibration characteristic of the PZT actuator was improved by using an electric field -150 kV/cm at 70 C for 30 min in poling process. A feasibility study on cell culture for delivering mechanical vibratory stimuli to cells revealed the microdevice could be applicable to the culture with actual biological cells. In addition, it was found that O 2 -plasma treated parylene-C process could be applicable for obtaining homogeneous surface of cell culture microdevice.

  4. Hybrid Polymer-Network Hydrogels with Tunable Mechanical Response

    Directory of Open Access Journals (Sweden)

    Sebastian Czarnecki

    2016-03-01

    Full Text Available Hybrid polymer-network gels built by both physical and covalent polymer crosslinking combine the advantages of both these crosslinking types: they exhibit high mechanical strength along with excellent fracture toughness and extensibility. If these materials are extensively deformed, their physical crosslinks can break such that strain energy is dissipated and irreversible fracturing is restricted to high strain only. This mechanism of energy dissipation is determined by the kinetics and thermodynamics of the physical crosslinking contribution. In this paper, we present a poly(ethylene glycol (PEG based material toolkit to control these contributions in a rational and custom fashion. We form well-defined covalent polymer-network gels with regularly distributed additional supramolecular mechanical fuse links, whose strength of connectivity can be tuned without affecting the primary polymer-network composition. This is possible because the supramolecular fuse links are based on terpyridine–metal complexation, such that the mere choice of the fuse-linking metal ion adjusts their kinetics and thermodynamics of complexation–decomplexation, which directly affects the mechanical properties of the hybrid gels. We use oscillatory shear rheology to demonstrate this rational control and enhancement of the mechanical properties of the hybrid gels. In addition, static light scattering reveals their highly regular and well-defined polymer-network structures. As a result of both, the present approach provides an easy and reliable concept for preparing hybrid polymer-network gels with rationally designed properties.

  5. MATHEMATICAL MODEL OF A QUICK-DRIVING ACTUATOR OF AN AUTOMATIC SWITCH WITH AN INSTANT-DYNAMIC AND BISTABLE MECHANISM

    Directory of Open Access Journals (Sweden)

    E. I. BAIDA

    2018-05-01

    Full Text Available Purpose. Development of a mathematical model of an induction-dynamic drive of a switch with two coils, working with a bistable mechanism, which ensures the fixation of the instant-dynamic mechanism (IDM in trajectory extreme positions of the contact system. Methodology. The solution of the problems posed in the work was carried out using methods for calculating the electromagnetic field, finite elements, theoretical mechanics, and solving differential equations. Findings. The mathematical model of quick-driving actuator as part of instant dynamic and bistable mechanism was developed. It was based on electrical circuit’s electromagnetic equations and kinematic movements of the switching mechanism. Advantage of the given model is possibility of a breaker drive dynamic analysis basing on data of a contact pressure, pretravel and snatch gap. Initial data of the model formulation were outer circuit inductance, resistance of coils, which calculated on conductor cross-section and coils configuration. Initial conditions corresponded by Dirichlet conditions. Mathematical model equations system was calculated in cylindrical coordinate system. Problem was solved with the help ComsolMultiphysics system. Motion of the IDM movement part was modeled by deformation of a computational grid. Spring force and stress in a bistable mechanism construction were determined by initial data of a contact pressure, pretravel and snatch gap. Graphs by calculation data are shown, which allow to analyze of springing elements chose and make necessary adjustments on design stage and debugging construction. Operation parameters of mechanism work on IDM switch on and switch off stages were calculated. Value of movement, motion speed of armature breaker, currents of accelerating and retarding coils, summed electromagnetic and opposite force were figured. Originality. The mathematical model of quick-driving actuator as part of instant-dynamic and bistable mechanism was developed

  6. Phase lag deduced information in photo-thermal actuation for nano-mechanical systems characterization

    NARCIS (Netherlands)

    Bijster, R.J.F.; Vreugd, J. de; Sadeghian Marnani, H.

    2014-01-01

    In photo-thermal actuation, heat is added locally to a micro-cantilever by means of a laser. A fraction of the irradiation is absorbed, yielding thermal stresses and deformations in the structure. Harmonic modulation of the laser power causes the cantilever to oscillate. Moreover, a phase lag is

  7. Large displacement spring-like electro-mechanical thermal actuators with insulator constraint beams

    Science.gov (United States)

    Luo, J. K.; Fu, Y. Q.; Flewitt, A. J.; Spearing, S. M.; Fleck, N. A.; Milne, W. I.

    2005-07-01

    A number of in-plane spring-like micro-electro-thermal-actuators with large displacements were proposed. The devices take the advantage of the large difference in the thermal expansion coefficients between the conductive arms and the insulator clamping beams. The constraint beams in one type (the spring) of these devices are horizontally positioned to restrict the expansion of the active arms in the x-direction, and to produce a displacement in the y-direction only. In other two types of actuators (the deflector and the contractor), the constraint beams are positioned parallel to the active arms. When the constraint beams are on the inside of the active arms, the actuator produces an outward deflection in the y-direction. When they are on the outside of the active arms, the actuator produces an inward contraction. Analytical model and finite element analysis were used to simulate the performances. It showed that at a constant temperature, analytical model is sufficient to predict the displacement of these devices. The displacements are all proportional to the temperature and the number of the chevron sections. A two-mask process is under development to fabricate these devices, using Si3N4 as the insulator beams, and electroplated Ni as the conductive beams.

  8. Single motor–variable stiffness actuator using bistable switching mechanisms for independent motion and stiffness control

    NARCIS (Netherlands)

    Groothuis, Stefan; Carloni, Raffaella; Stramigioli, Stefano

    This paper presents a proof of concept of a variable stiffness actuator (VSA) that uses only one (high power) input motor. In general, VSAs use two (high power) motors to be able to control both the output position and the output stiffness, which possibly results in a heavy, and bulky system. In

  9. Preheating Mechanism in F-term SUSY Hybrid Inflation

    International Nuclear Information System (INIS)

    Mazumdar, Arindam

    2012-01-01

    Supersymmetric F-term hybrid inflation is one of the most popular models of inflation. Preheating process occurs in this model via two different mechanism. Firstly the standard parametric resonance and secondly, the tachyonic preheating. Generally tachyonic preheating dominates the parametric resonance for this type of models. For different values of the parameters of the theory dominance of tachyonic preheating can vary.

  10. Analysis of a Hybrid Mechanical Regenerative Braking System

    Directory of Open Access Journals (Sweden)

    Toh Xiang Wen Matthew

    2018-01-01

    Full Text Available Regenerative braking systems for conventional vehicles are gaining attention as fossil fuels continue to be depleted. The major forms of regenerative braking systems include electrical and mechanical systems, with the former being more widely adopted at present. However mechanical systems are still feasible, including the possible hybrid systems of two mechanical energy recovery systems. A literature study was made to compare the various mechanical energy recovery systems. These systems were compared based on their advantages and disadvantages with regards to energy storage, usage, and maintenance. Based on the comparison, the most promising concept appeared to be one that combined the flywheel and the pneumatic energy recovery systems. A CAD model of this hybrid system was produced to better visualise the design. This was followed by analytical modelling of the energy recovery systems. The analysis indicated that the angular velocity had an extremely significant impact on the power loss and energy efficiency. The results showed that the hybrid system can provide better efficiency but only when operating within certain parameters. Future work is required to further improve the efficiency of this hybrid system.

  11. Effect of glass hybridization and staking sequence on mechanical ...

    Indian Academy of Sciences (India)

    Coir fibre; glass fibre; polyester resin; hybrid laminate; mechanical properties. 1. Introduction. Natural fibres exhibit many advantageous properties as rein- forcement in fibre-reinforced composites. They are low- density materials, yielding relatively light weight composites with specific properties. In an effort to develop a ...

  12. A Novel Hybrid Error Criterion-Based Active Control Method for on-Line Milling Vibration Suppression with Piezoelectric Actuators and Sensors

    Directory of Open Access Journals (Sweden)

    Xingwu Zhang

    2016-01-01

    Full Text Available Milling vibration is one of the most serious factors affecting machining quality and precision. In this paper a novel hybrid error criterion-based frequency-domain LMS active control method is constructed and used for vibration suppression of milling processes by piezoelectric actuators and sensors, in which only one Fast Fourier Transform (FFT is used and no Inverse Fast Fourier Transform (IFFT is involved. The correction formulas are derived by a steepest descent procedure and the control parameters are analyzed and optimized. Then, a novel hybrid error criterion is constructed to improve the adaptability, reliability and anti-interference ability of the constructed control algorithm. Finally, based on piezoelectric actuators and acceleration sensors, a simulation of a spindle and a milling process experiment are presented to verify the proposed method. Besides, a protection program is added in the control flow to enhance the reliability of the control method in applications. The simulation and experiment results indicate that the proposed method is an effective and reliable way for on-line vibration suppression, and the machining quality can be obviously improved.

  13. Parameter design and performance analysis of shift actuator for a two-speed automatic mechanical transmission for pure electric vehicles

    Directory of Open Access Journals (Sweden)

    Jianjun Hu

    2016-08-01

    Full Text Available Recent developments of pure electric vehicles have shown that pure electric vehicles equipped with two-speed or multi-speed gearbox possess higher energy efficiency by ensuring the drive motor operates at its peak performance range. This article presents the design, analysis, and control of a two-speed automatic mechanical transmission for pure electric vehicles. The shift actuator is based on a motor-controlled camshaft where a special geometric groove is machined, and the camshaft realizes the axial positions of the synchronizer sleeve for gear engaging, disengaging, and speed control of the drive motor. Based on the force analysis of shift process, the parameters of shift actuator and shift motor are designed. The drive motor’s torque control strategy before shifting, speed governing control strategy before engaging, shift actuator’s control strategy during gear engaging, and drive motor’s torque recovery strategy after shift process are proposed and implemented with a prototype. To validate the performance of the two-speed gearbox, a test bed was developed based on dSPACE that emulates various operation conditions. The experimental results indicate that the shift process with the proposed shift actuator and control strategy could be accomplished within 1 s under various operation conditions, with shift smoothness up to passenger car standard.

  14. A springs actuated finger exoskeleton: From mechanical design to spring variables evaluation.

    Science.gov (United States)

    Bortoletto, Roberto; Mello, Ashley N; Piovesan, Davide

    2017-07-01

    In the context of post-stroke patients, suffering of hemiparesis of the hand, robot-aided neuro-motor rehabilitation allows for intensive rehabilitation treatments and quantitative evaluation of patients' progresses. This work presents the design and evaluation of a spring actuated finger exoskeleton. In particular, the spring variables and the interaction forces between the assembly and the hand were investigated, in order to assess the effectiveness of the proposed exoskeleton.

  15. Electric and hydraulic hybrid actuator. Competing and complementary systems?; Elektrische und hydraulische Hybridantriebe. Konkurrierende oder komplementaere Systeme?

    Energy Technology Data Exchange (ETDEWEB)

    Dehnert, Klaus [Eaton Corporation, Rastatt (Germany)

    2011-07-01

    Hybrid drives for commercial vehicles and for mobile processing machines are evolving rapidly to a future-oriented technology. Hybrid drives significantly affect issues such as fuel efficiency, emissions, productivity and life cycle cost. For recovery and storage of kinetic energy, different technologies are used. Under this aspect, the author of the contribution under consideration reports on the key distinguishing features of some currently available hybrid concepts and their appropriate application. In the selection of suitable hydraulic hybrid drive systems, the essential features of different hybrid systems have to be considered.

  16. Integration of Plasticity Mechanisms within a Single Sensory Neuron of C. elegans Actuates a Memory.

    Science.gov (United States)

    Hawk, Josh D; Calvo, Ana C; Liu, Ping; Almoril-Porras, Agustin; Aljobeh, Ahmad; Torruella-Suárez, María Luisa; Ren, Ivy; Cook, Nathan; Greenwood, Joel; Luo, Linjiao; Wang, Zhao-Wen; Samuel, Aravinthan D T; Colón-Ramos, Daniel A

    2018-01-17

    Neural plasticity, the ability of neurons to change their properties in response to experiences, underpins the nervous system's capacity to form memories and actuate behaviors. How different plasticity mechanisms act together in vivo and at a cellular level to transform sensory information into behavior is not well understood. We show that in Caenorhabditis elegans two plasticity mechanisms-sensory adaptation and presynaptic plasticity-act within a single cell to encode thermosensory information and actuate a temperature preference memory. Sensory adaptation adjusts the temperature range of the sensory neuron (called AFD) to optimize detection of temperature fluctuations associated with migration. Presynaptic plasticity in AFD is regulated by the conserved kinase nPKCε and transforms thermosensory information into a behavioral preference. Bypassing AFD presynaptic plasticity predictably changes learned behavioral preferences without affecting sensory responses. Our findings indicate that two distinct neuroplasticity mechanisms function together through a single-cell logic system to enact thermotactic behavior. VIDEO ABSTRACT. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Generation of Compliant Mechanisms using Hybrid Genetic Algorithm

    Science.gov (United States)

    Sharma, D.; Deb, K.

    2014-10-01

    Compliant mechanism is a single piece elastic structure which can deform to perform the assigned task. In this work, compliant mechanisms are evolved using a constraint based bi-objective optimization formulation which requires one user defined parameter ( η). This user defined parameter limits a gap between a desired path and an actual path traced by the compliant mechanism. The non-linear and discrete optimization problems are solved using the hybrid Genetic Algorithm (GA) wherein domain specific initialization, two-dimensional crossover operator and repairing techniques are adopted. A bit-wise local search method is used with elitist non-dominated sorting genetic algorithm to further refine the compliant mechanisms. Parallel computations are performed on the master-slave architecture to reduce the computation time. A parametric study is carried out for η value which suggests a range to evolve topologically different compliant mechanisms. The applied and boundary conditions to the compliant mechanisms are considered the variables that are evolved by the hybrid GA. The post-analysis of results unveils that the complaint mechanisms are always supported at unique location that can evolve the non-dominated solutions.

  18. Structural Interplay - Tuning Mechanics in Peptide-Polyurea Hybrids

    Science.gov (United States)

    Korley, Lashanda

    Utilizing cues from natural materials, we have been inspired to explore the hierarchical arrangement critical to energy absorption and mechanical enhancement in synthetic systems. Of particular interest is the soft domain ordering proposed as a contributing element to the observed toughness in spider silk. Multiblock copolymers, are ideal and dynamic systems in which to explore this approach via variations in secondary structure of nature's building blocks - peptides. We have designed a new class of polyurea hybrids that incorporate peptidic copolymers as the soft segment. The impact of hierarchical ordering on the thermal, mechanical, and morphological behavior of these bio-inspired polyurethanes with a siloxane-based, peptide soft segment was investigated. These peptide-polyurethane/urea hybrids were microphase segregated, and the beta-sheet secondary structure of the soft segment was preserved during polymerization and film casting. Toughness enhancement at low strains was achieved, but the overall extensibility of the peptide-incorporated systems was reduced due to the unique hard domain organization. To decouple the secondary structure influence in the siloxane-peptide soft segment from mechanics dominated by the hard domain, we also developed non-chain extended peptide-polyurea hybrids in which the secondary structure (beta sheet vs. alpha helix) was tuned via choice of peptide and peptide length. It was shown that this structural approach allowed tailoring of extensibility, toughness, and modulus. The sheet-dominant hybrid materials were typically tougher and more elastic due to intermolecular H-bonding facilitating load distribution, while the helical-prevalent systems generally exhibited higher stiffness. Recently, we have explored the impact of a molecular design strategy that overlays a covalent and physically crosslinked architecture in these peptide-polyurea hybrids, demonstrating that physical constraints in the network hybrids influences peptide

  19. Dynamic Modeling and Nonlinear Position Control of a Quadruped Robot with Theo Jansen Linkage Mechanisms and a Single Actuator

    Directory of Open Access Journals (Sweden)

    Shunsuke Nansai

    2015-01-01

    Full Text Available The Theo Jansen mechanism is gaining widespread popularity among the legged robotics community due to its scalable design, energy efficiency, low payload-to-machine-load ratio, bioinspired locomotion, and deterministic foot trajectory. In this paper, we perform for the first time the dynamic modeling and analysis on a four-legged robot driven by a single actuator and composed of Theo Jansen mechanisms. The projection method is applied to derive the equations of motion of this complex mechanical system and a position control strategy based on energy is proposed. Numerical simulations validate the efficacy of the designed controller, thus setting a theoretical basis for further investigations on Theo Jansen based quadruped robots.

  20. Advanced Electroactive Single Crystal and Polymer Actuator Concepts for Passive Optics, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes large stroke and high precision piezoelectric single crystal and electroactive polymer actuator concepts?HYBrid Actuation System (HYBAS)...

  1. An Experimental Evaluation of Mechanical Properties of Hybrid Reinforcements

    Science.gov (United States)

    Sai Kumar, A.; Ganesan, G.; Karthikeyan, K.

    2017-07-01

    This paper presents the mechanical properties of unidirectional hybrid reinforcements formed from continuous fibres impregnated with a fibre binding material which are used for reinforcing the concrete. Recently FRP (Fibre Reinforced Polymer) manufacturers and suppliers have been increased all over the world because of the superior performance of FRP products in the construction industry. Its non-corrosive nature has turned the attention of many researchers to make several studies on different type of FRP products. Through a vast research, several standards also have been formulated. In this regard a new combination of FRP materials is tried in this paper and its properties have been derived. Carbon fibre and glass fibres fuse in this study to form a new hybrid rebar. The design properties such as tensile strength, tensile modulus, and compressive strength have been studied as per ASTM standards and it has been identified that the Hybrid rebar show a superior performance in comparison with GFRP (Glass FRP) and Steel rebars. This extraordinary performance of hybrid composite material increases the extensive engineering applications such as transport industry, aeronautics, naval, automotive industries.

  2. Plug-and-actuate on demand: multimodal individual addressability of microarray plates using modular hybrid acoustic wave technology.

    Science.gov (United States)

    Rezk, Amgad R; Ramesan, Shwathy; Yeo, Leslie Y

    2018-01-30

    The microarray titre plate remains a fundamental workhorse in genomic, proteomic and cellomic analyses that underpin the drug discovery process. Nevertheless, liquid handling technologies for sample dispensing, processing and transfer have not progressed significantly beyond conventional robotic micropipetting techniques, which are not only at their fundamental sample size limit, but are also prone to mechanical failure and contamination. This is because alternative technologies to date suffer from a number of constraints, mainly their limitation to carry out only a single liquid operation such as dispensing or mixing at a given time, and their inability to address individual wells, particularly at high throughput. Here, we demonstrate the possibility for true sequential or simultaneous single- and multi-well addressability in a 96-well plate using a reconfigurable modular platform from which MHz-order hybrid surface and bulk acoustic waves can be coupled to drive a variety of microfluidic modes including mixing, sample preconcentration and droplet jetting/ejection in individual or multiple wells on demand, thus constituting a highly versatile yet simple setup capable of improving the functionality of existing laboratory protocols and processes.

  3. Improvement of fatigue resistance for multilayer lead zirconate titanate (PZT)-based ceramic actuators by external mechanical loads

    Science.gov (United States)

    Yang, Gang; Yue, Zhenxing; Ji, Ye; Chu, Xiangcheng; Li, Longtu

    2008-12-01

    The influence of external compressive loads, applied along a direction perpendicular to polarization, on fatigue behaviors of multilayer lead zirconate titanate (PZT)-based ceramic actuators was investigated. Under no external mechanical load, a normal fatigue behavior was observed, demonstrating that both switching polarization (Pswitching) and remnant polarization (Pr) progressively decreased with increasing switching cycles due to domain pinning by charge point defects. However, an anomalous enhancement in both switching and remnant polarizations was observed upon application of the external compressive loads. After 5×106 cycles of polarization switching, Pswitching and Pr increase by about 13% and 6% at 40 MPa, respectively, while Pswitching and Pr increase by about 11% and 21% at 60 MPa, respectively. The improvement of fatigue resistance can be attributed to non-180° domain switching and suppression of microcracking, triggered by external mechanical loads.

  4. Drilling, Coring and Sampling Using Piezoelectric Actuated Mechanisms: From the USDC to a Piezo-Rotary-Hammer Drill

    Science.gov (United States)

    Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Bao, Xiaoqi

    2012-01-01

    NASA exploration missions are increasingly including sampling tasks but with the growth in engineering experience (particularly, Phoenix Scout and MSL) it is now very much recognized that planetary drilling poses many challenges. The difficulties grow significantly with the hardness of sampled material, the depth of drilling and the harshness of the environmental conditions. To address the requirements for samplers that could be operated at the conditions of the various bodies in the solar system, a number of piezoelectric actuated drills and corers were developed by the Advanced Technologies Group of JPL. The basic configuration that was conceived in 1998 is known as the Ultrasonic/Sonic Driller/Corer (USDC), and it operates as a percussive mechanism. This drill requires as low preload as 10N (important for operation at low gravity) allowing to operate with as low-mass device as 400g, use an average power as low as 2- 3W and drill rocks as hard as basalt. A key feature of this drilling mechanism is the use of a free-mass to convert the ultrasonic vibrations generated by piezoelectric stack to sonic impacts on the bit. Using the versatile capabilities f the USDC led to the development of many configurations and device sizes. Significant improvement of the penetration rate was achieved by augmenting the hammering action by rotation and use of a fluted bit to remove cuttings. To reach meters deep in ice a wireline drill was developed called the Ultrasonic/Sonic Gopher and it was demonstrated in 2005 to penetrate about 2-m deep at Antarctica. Jointly with Honeybee Robotics, this mechanism is currently being modified to incorporate rotation and inchworm operation forming Auto-Gopher to reach meters deep in rocks. To take advantage of the ability of piezoelectric actuators to operate over a wide temperatures range, piezoelectric actuated drills were developed and demonstrated to operate at as cold as -200oC and as hot as 500oC. In this paper, the developed mechanisms

  5. Variable load failure mechanism for high-speed load sensing electro-hydrostatic actuator pump of aircraft

    Directory of Open Access Journals (Sweden)

    Cun SHI

    2018-05-01

    Full Text Available This paper presents a novel transient lubrication model for the analysis of the variable load failure mechanism of high-speed pump used in Load Sensing Electro-Hydrostatic Actuator (LS-EHA. Focusing on the slipper/swashplate pair partial abrasion, which is considered as the dominant failure mode in the high-speed condition, slipper dynamic models are established. A forth sliding motion of the slipper on the swashplate surface is presented under the fact that the slipper center of mass will rotate around the center of piston ball when the swashplate angle is dynamically adjusted. Besides, extra inertial tilting moments will be produced for the slipper based on the theorem on translation of force, which will increase rapidly when LS-EHA pump operates under high-speed condition. Then, a dynamic lubricating model coupling with fluid film thickness field, temperature field and pressure field is proposed. The deformation effects caused by thermal deflection and hydrostatic pressure are considered. A numerical simulation model is established to validate the effectiveness and accuracy of the proposed model. Finally, based on the load spectrum of aircraft flight profile, the variable load conditions and the oil film characteristics are analyzed, and series of variable load rules of oil film thickness with variable speed/variable pressure/variable displacement are concluded. Keywords: Coupling lubrication model, Electro-Hydrostatic Actuator (EHA, High-speed pump, Partial abrasion, Slipper pair, Variable load

  6. Experimental/analytical determination of optimal piezoelectric actuator locations on complex structures based on the actuator power factor

    OpenAIRE

    Bhargava, Adesh

    1995-01-01

    The actuator power factor is defined as the ratio of the total dissipative mechanical power of a PZT actuator to the total supplied electrical power to the PZT actuator. If measured experimentally, it can be used to optinlize the actuator location and configuration for complex structures. The concept of actuator power factor is based on the ability of an integrated induced strain actuator such as a PZT actuator to transfer supplied electrical energy into structural mechanical energy. For a gi...

  7. Mechatronics Approach for a Controlled Actuation of the Presser Foot Mechanism on an Industrial Sewing Machine

    Directory of Open Access Journals (Sweden)

    L. F. Silva

    2000-01-01

    Full Text Available This paper describes the study of the research program being carried out on the feeding system of an industrial overlock sewing machine. The results obtained from the presser foot bar displacement and compression force, together with the graphic kinematic analysis, which includes the velocity and acceleration taken from the displacement-time curves of the presser bar, led to further understanding of the feeding system dynamics. This study is providing the basis for the development of a redesigned and optimized fabric feeding system. The new actuation system, based on a proportional force solenoid integrated in the presser foot bar, will be also discussed as an important contribution to achieving a desired dynamic behaviour at high sewing speeds.

  8. Investigations on mechanical properties of aluminum hybrid composites

    Directory of Open Access Journals (Sweden)

    Dora Siva Prasad

    2014-01-01

    Full Text Available A double stir casting process was used to fabricate aluminum composites reinforced with various volume fractions of 2, 4, 6, and 8 wt% RHA and SiC particulates in equal proportions. Properties such as hardness, density, porosity and mechanical behavior of the unreinforced and Al/x%RHA/x%SiC (x = 2, 4, 6, and 8 wt% reinforced hybrid composites were examined. Scanning electron microscope (model JSM-6610LV was used to study the microstructural characterization of the composites. It was observed that the hardness and porosity of the hybrid composite increased with increasing reinforcement volume fraction and density decreased with increasing particle content. It was also observed that the UTS and yield strength increase with an increase in the percent weight fraction of the reinforcement particles, whereas elongation decreases with the increase in reinforcement. The increase in strength of the hybrid composites is probably due to the increase in dislocation density. A systematic study of the base alloy and composites was done using the Brinell hardness measurement and the corresponding age hardening curves were obtained. It was observed that in comparison to that of the base aluminum alloy, the precipitation kinetics of the composites were accelerated by adding the reinforcement. This effectively reduced the time for obtaining the maximum hardness by the aging heat treatment.

  9. Clean room actuators

    Energy Technology Data Exchange (ETDEWEB)

    Higuchi, Toshiro

    1987-06-01

    This report explains on the present status of the clean room actuators including the author's research results. In a clean room, there exists a possibility of dust generation, even when a direct human work is eliminated by the use of robots or automatic machines, from the machines themselves. For this, it is important to develop such clean robots and transfer/positioning mechanism that do not generate dusts, and to develop an actuator and its control technique. Topics described in the report are as follows: 1. Prevention of dust diffusion by means of sealing. 2. Elimination of mechanical contact (Linear induction motor and pneumatic float, linear motor and magnetic attraction float, linear motor and air bearing, and magnetic bearing). 3. Contactless actuator having a positioning mechanism (Use of linear step motor and rotary contactless actuator). (15 figs, 11 refs)

  10. Studying the Mechanism of Hybrid Nanoparticle Photoresists: Effect of Particle Size on Photopatterning

    KAUST Repository

    Li, Li; Chakrabarty, Souvik; Spyrou, Konstantinos; Ober, Christopher K.; Giannelis, Emmanuel P.

    2015-01-01

    © 2015 American Chemical Society. Hf-based hybrid photoresist materials with three different organic ligands were prepared by a sol-gel-based method, and their patterning mechanism was investigated in detail. All hybrid nanoparticle resists

  11. Development of a 3D parallel mechanism robot arm with three vertical-axial pneumatic actuators combined with a stereo vision system.

    Science.gov (United States)

    Chiang, Mao-Hsiung; Lin, Hao-Ting

    2011-01-01

    This study aimed to develop a novel 3D parallel mechanism robot driven by three vertical-axial pneumatic actuators with a stereo vision system for path tracking control. The mechanical system and the control system are the primary novel parts for developing a 3D parallel mechanism robot. In the mechanical system, a 3D parallel mechanism robot contains three serial chains, a fixed base, a movable platform and a pneumatic servo system. The parallel mechanism are designed and analyzed first for realizing a 3D motion in the X-Y-Z coordinate system of the robot's end-effector. The inverse kinematics and the forward kinematics of the parallel mechanism robot are investigated by using the Denavit-Hartenberg notation (D-H notation) coordinate system. The pneumatic actuators in the three vertical motion axes are modeled. In the control system, the Fourier series-based adaptive sliding-mode controller with H(∞) tracking performance is used to design the path tracking controllers of the three vertical servo pneumatic actuators for realizing 3D path tracking control of the end-effector. Three optical linear scales are used to measure the position of the three pneumatic actuators. The 3D position of the end-effector is then calculated from the measuring position of the three pneumatic actuators by means of the kinematics. However, the calculated 3D position of the end-effector cannot consider the manufacturing and assembly tolerance of the joints and the parallel mechanism so that errors between the actual position and the calculated 3D position of the end-effector exist. In order to improve this situation, sensor collaboration is developed in this paper. A stereo vision system is used to collaborate with the three position sensors of the pneumatic actuators. The stereo vision system combining two CCD serves to measure the actual 3D position of the end-effector and calibrate the error between the actual and the calculated 3D position of the end-effector. Furthermore, to

  12. A micro-optical system for endoscopy based on mechanical compensation paradigm using miniature piezo-actuation.

    Science.gov (United States)

    Cerveri, Pietro; Zazzarini, Cynthia Corinna; Patete, Paolo; Baroni, Guido

    2014-06-01

    The goal of the study was to investigate the feasibility of a novel miniaturized optical system for endoscopy. Fostering the mechanical compensation paradigm, the modeled optical system, composed by 14 lenses, separated in 4 different sets, had a total length of 15.55mm, an effective focal length ranging from 1.5 to 4.5mm with a zoom factor of about 2.8×, and an angular field of view up to 56°. Predicted maximum lens travel was less than 3.5mm. The consistency of the image plane height across the magnification range testified the zoom capability. The maximum predicted achromatic astigmatism, transverse spherical aberration, longitudinal spherical aberration and relative distortion were less than or equal to 25μm, 15μm, 35μm and 12%, respectively. Tests on tolerances showed that the manufacturing and opto-mechanics mounting are critical as little deviations from design dramatically decrease the optical performances. However, recent micro-fabrication technology can guarantee tolerances close to nominal design. A closed-loop actuation unit, devoted to move the zoom and the focus lens sets, was implemented adopting miniaturized squiggle piezo-motors and magnetic position encoders based on Hall effect. Performance results, using a prototypical test board, showed a positioning accuracy of less than 5μm along a lens travel path of 4.0mm, which was in agreement with the lens set motion features predicted by the analysis. In conclusion, this study demonstrated the feasibility of the optical design and the viability of the actuation approach while tolerances must be carefully taken into account. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

  13. Development of a hybrid chemical/mechanical heat pump

    Science.gov (United States)

    Grzyll, Lawrence R.; Silvestri, John J.; Scaringe, Robert P.

    1991-01-01

    The authors present the current development status of a hybrid chemical/mechanical heat pump for low-lift applications. The heat pump provides electronics cooling by evaporating a pure refrigerant from an absorbent/refrigerant mixture in a generator/cold plate. The current development focused on evaluation of absorbent/refrigerant pairs, corrosion testing, pump and compressor design, and electronic cold plate design. Two cycle configurations were considered. The first configuration utilized a standard mechanical compressor and pump. The second cycle configuration investigated pumps and compressors with non-moving parts. An innovative generator/cold plate design is also presented. The development to date shows that this cycle has about the same performance as standard vapor compression heat pumps with standard refrigerants but may have some performance and reliability advantages over vapor compression heat pumps.

  14. Bioprinting of hybrid tissue constructs with tailorable mechanical properties

    International Nuclear Information System (INIS)

    Schuurman, W; Khristov, V; Pot, M W; Dhert, W J A; Malda, J; Van Weeren, P R

    2011-01-01

    Tissue/organ printing aims to recapitulate the intrinsic complexity of native tissues. For a number of tissues, in particular those of musculoskeletal origin, adequate mechanical characteristics are an important prerequisite for their initial handling and stability, as well as long-lasting functioning. Hence, organized implants, possessing mechanical characteristics similar to the native tissue, may result in improved clinical outcomes of regenerative approaches. Using a bioprinter, grafts were constructed by alternate deposition of thermoplastic fibers and (cell-laden) hydrogels. Constructs of different shapes and sizes were manufactured and mechanical properties, as well as cell viability, were assessed. This approach yields novel organized viable hybrid constructs, which possess favorable mechanical characteristics, within the same range as those of native tissues. Moreover, the approach allows the use of multiple hydrogels and can thus produce constructs containing multiple cell types or bioactive factors. Furthermore, since the hydrogel is supported by the thermoplastic material, a broader range of hydrogel types can be used compared to bioprinting of hydrogels alone. In conclusion, we present an innovative and versatile approach for bioprinting, yielding constructs of which the mechanical stiffness provided by thermoplastic polymers can potentially be tailored, and combined specific cell placement patterns of multiple cell types embedded in a wide range of hydrogels. (communication)

  15. Bioprinting of hybrid tissue constructs with tailorable mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Schuurman, W; Khristov, V; Pot, M W; Dhert, W J A; Malda, J [Department of Orthopaedics, University Medical Center Utrecht (Netherlands); Van Weeren, P R, E-mail: j.malda@umcutrecht.nl [Faculty of Veterinary Sciences, Department of Equine Sciences, Utrecht University (Netherlands)

    2011-06-15

    Tissue/organ printing aims to recapitulate the intrinsic complexity of native tissues. For a number of tissues, in particular those of musculoskeletal origin, adequate mechanical characteristics are an important prerequisite for their initial handling and stability, as well as long-lasting functioning. Hence, organized implants, possessing mechanical characteristics similar to the native tissue, may result in improved clinical outcomes of regenerative approaches. Using a bioprinter, grafts were constructed by alternate deposition of thermoplastic fibers and (cell-laden) hydrogels. Constructs of different shapes and sizes were manufactured and mechanical properties, as well as cell viability, were assessed. This approach yields novel organized viable hybrid constructs, which possess favorable mechanical characteristics, within the same range as those of native tissues. Moreover, the approach allows the use of multiple hydrogels and can thus produce constructs containing multiple cell types or bioactive factors. Furthermore, since the hydrogel is supported by the thermoplastic material, a broader range of hydrogel types can be used compared to bioprinting of hydrogels alone. In conclusion, we present an innovative and versatile approach for bioprinting, yielding constructs of which the mechanical stiffness provided by thermoplastic polymers can potentially be tailored, and combined specific cell placement patterns of multiple cell types embedded in a wide range of hydrogels. (communication)

  16. Hybrid plasmonic nanodevices: Switching mechanism for the nonlinear emission

    Energy Technology Data Exchange (ETDEWEB)

    Bragas, Andrea V. [Departamento de Física, FCEyN, Universidad de Buenos Aires, IFIBA CONICET, 1428 Buenos Aires (Argentina); Singh, Mahi R. [Department of Physics and Astronomy, Western University, London (Canada)

    2014-03-31

    Control of the light emission at the nanoscale is of central interest in nanophotonics due to the many applications in very different fields, ranging from quantum information to biophysics. Resonant excitation of surface plasmon polaritons in metal nanoparticles create nanostructured and enhanced light fields around those structures, which produce their strong interaction in a hybrid nanodevice with other plasmonic or non-plasmonic objects. This interaction may in turn also modulate the far field with important consequences in the applications. We show in this paper that the nonlinear emission from semiconductor quantum dots is strongly affected by the close presence of metal nanoparticles, which are resonantly excited. Using a pulsed laser, optical second harmonic is generated in the quantum dot, and it is highly enhanced when the laser is tuned around the nanoparticle plasmon resonance. Even more interesting is the demonstration of a switching mechanism, controlled by an external continuous-wave field, which can enhance or extinguish the SH signal, even when the pulsed laser is always on. Experimental observations are in excellent agreement with the theoretical calculations, based on the dipole-dipole near-field coupling of the objects forming the hybrid system.

  17. Conjugated Polymers as Actuators: Modes of Actuation

    DEFF Research Database (Denmark)

    Skaarup, Steen

    2004-01-01

    The physical and chemical properties of conjugated polymers often depend very strongly on the degree of doping with anions or cations. The movement of ions in and out of the polymer matrix as it is redox cycled is also accompanied by mechanical changes. Both the volume and the stiffness can exhibit...... significant differences between the oxidized and reduced states. These effects form the basis of the use of conjugated polymers as actuators (or “artificial muscles”) controllable by a small (1-10 V) voltage. Three basic modes of actuation (bending, linear extension and stiffness change) have been proposed...

  18. Conjugated polymers as actuators: modes of actuation

    DEFF Research Database (Denmark)

    Skaarup, Steen

    2007-01-01

    The physical and chemical properties of conjugated polymers often depend very strongly on the degree of doping with anions or cations. The movement of ions in and out of the polymer matrix as it is redox cycled is also accompanied by mechanical changes. Both the volume and the stiffness can exhibit...... significant differences between the oxidized and reduced states. These effects form the basis of the use of conjugated polymers as actuators (or “artificial muscles”) controllable by a small (1-10 V) voltage. Three basic modes of actuation (bending, linear extension and stiffness change) have been proposed...

  19. A Hybrid Imperative and Functional Molecular Mechanics Application

    Directory of Open Access Journals (Sweden)

    Thomas Deboni

    1996-01-01

    Full Text Available Molecular mechanics applications model the interactions among large ensembles of discrete particles. They are used where probabilistic methods are inadequate, such as drug chemistry. This methodology is difficult to parallelize with good performance, due to its poor locality, uneven partitions, and dynamic behavior. Imperative programs have been written that attempt this on shared and distributed memory machines. Given such a program, the computational kernel can be rewritten in Sisal, a functional programming language, and integrated with the rest of the imperative program under the Sisal Foreign Language Interface. This allows minimal effort and maximal return from parallelization work, and leaves the work appropriate to imperative implementation in its original form. We describe such an effort, focusing on the parts of the application that are appropriate for Sisal implementation, the specifics of mixed-language programming, and the complex performance behavior of the resulting hybrid code.

  20. Studying the mechanism of hybrid nanoparticle EUV photoresists

    KAUST Repository

    Zhang, Ben

    2015-03-23

    This work focuses on the investigation of dual tone patterning mechanism with hybrid inorganic/organic photoresists. Hafnium oxide (HfO2) modified with acrylic acid was prepared and the influence of electrolyte solutions as well as pH on its particle size change was investigated. The average particle size and zeta potential of the nanoparticles in different electrolyte solutions were measured. The results show that addition of different concentrations of electrolytes changed the hydrodynamic diameter of nanoparticles in water. Increased concentration of tetramethyl ammonium hydroxide (TMAH) caused the zeta potential of nanoparticles to change from positive to negative and its hydrodynamic diameter to increase from 40 nm to 165 nm. In addition, increasing concentration of triflic acid led to the decrease of particle size and zeta potential. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  1. Studying the mechanism of hybrid nanoparticle EUV photoresists

    KAUST Repository

    Zhang, Ben; Li, Li; Jiang, Jing; Neisser, Mark; Chun, Jun Sung; Ober, Christopher K.; Giannelis, Emmanuel P.

    2015-01-01

    This work focuses on the investigation of dual tone patterning mechanism with hybrid inorganic/organic photoresists. Hafnium oxide (HfO2) modified with acrylic acid was prepared and the influence of electrolyte solutions as well as pH on its particle size change was investigated. The average particle size and zeta potential of the nanoparticles in different electrolyte solutions were measured. The results show that addition of different concentrations of electrolytes changed the hydrodynamic diameter of nanoparticles in water. Increased concentration of tetramethyl ammonium hydroxide (TMAH) caused the zeta potential of nanoparticles to change from positive to negative and its hydrodynamic diameter to increase from 40 nm to 165 nm. In addition, increasing concentration of triflic acid led to the decrease of particle size and zeta potential. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  2. Evaluating mechanical properties of hybrid laser arc girth welds

    Energy Technology Data Exchange (ETDEWEB)

    Pussegoda, L. N.; Begg, D.; Holdstock, R.; Jodoin, A. [BMT Fleet Technology Ltd Techonology, Kanata, ON, (Canada); Ligh, K.; Rondeau, D. [Appliead Thermal Sciences Inc., Sanford, ME, (United States); Hansen, E. [ESAB, Florence, SC, (United States)

    2010-07-01

    Hybrid laser arc welding (HLAW) is a promising new process for making girth welds on steel pipelines. This study investigated the mechanical properties of overmatched X80 and X100 pipeline steel girth welds made using the HLAW process. The testing of this process was conducted on NPS36 pipes of 10.4 mm and 14.3 mm thickness, respectively. Various weld positions were produced on X80 and X100 pipes. Laser inspection data were collected during the whole welding process. Also standard tests for girth welds, Charpy V-notch impact tests, CTOD tests, all weld metal (AWM) tension tests, were carried out. The results showed that the fracture transition temperature is higher at the 3 and 9 o'clock positions than at the 9 and 12 o'clock positions. The effect of clock position on fracture toughness is currently being explored; a modified CTOD has been developed to reduce the possibility of crack deviation.

  3. Experimental identification of piezo actuator characteristic

    Directory of Open Access Journals (Sweden)

    Ľ. Miková

    2015-01-01

    Full Text Available This paper deals with piezoelectric material, which can be used as actuator for conversion of electrical energy to mechanical work. Test equipment has been developed for experimental testing of the piezoactuators. Piezoactivity of this actuator has non-linear characteristic. This type of actuator is used for in-pipe mechanism design.

  4. Hybrid female mate choice as a species isolating mechanism: environment matters.

    Science.gov (United States)

    Schmidt, E M; Pfennig, K S

    2016-04-01

    A fundamental goal of biology is to understand how new species arise and are maintained. Female mate choice is potentially critical to the speciation process: mate choice can prevent hybridization and thereby generate reproductive isolation between potentially interbreeding groups. Yet, in systems where hybridization occurs, mate choice by hybrid females might also play a key role in reproductive isolation by affecting hybrid fitness and contributing to patterns of gene flow between species. We evaluated whether hybrid mate choice behaviour could serve as such an isolating mechanism using spadefoot toad hybrids of Spea multiplicata and Spea bombifrons. We assessed the mate preferences of female hybrid spadefoot toads for sterile hybrid males vs. pure-species males in two alternative habitat types in which spadefoots breed: deep or shallow water. We found that, in deep water, hybrid females preferred the calls of sterile hybrid males to those of S. multiplicata males. Thus, maladaptive hybrid mate preferences could serve as an isolating mechanism. However, in shallow water, the preference for hybrid male calls was not expressed. Moreover, hybrid females did not prefer hybrid calls to those of S. bombifrons in either environment. Because hybrid female mate choice was context-dependent, its efficacy as a reproductive isolating mechanism will depend on both the environment in which females choose their mates as well as the relative frequencies of males in a given population. Thus, reproductive isolation between species, as well as habitat specific patterns of gene flow between species, might depend critically on the nature of hybrid mate preferences and the way in which they vary across environments. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

  5. Mechanical Design of a Hybrid Leg Exoskeleton to Augment Load-Carrying for Walking

    Directory of Open Access Journals (Sweden)

    Yunjie Miao

    2013-11-01

    Full Text Available An innovative lower extremity exoskeleton, SJTU-EX, is demonstrated in Shanghai JiaoTong University, which mainly aims to help soldiers and workers to support a payload in motion. This paper summarizes the mechanical design of SJTU-EX. Each pseudo-anthropomorphic leg of SJTU-EX has four active joints and two passive joints, and the joint ranges are optimized in consideration of both safety factors and the realization of typical motions. Springs are applied in the leg to eliminate the effect of gravity. The results of dynamic simulations are used to determine the actuated joints and the passive joints. Novel Hy-Mo actuators are introduced for SJTU-EX and the layout of the actuator for Diamond Side 2 is described in detail as a design example.

  6. SPRING Project on Mechanical Energy on Demand from High Strain Actuators

    Science.gov (United States)

    2009-09-02

    containing N-heterocycles and acidic functional groups Operation of a PEMFC under essentially water-free conditions involves a different mechanism...Temperature-Polymer Electrolyte Membrane-Fuel Cell (HT- PEMFC ) Based on Functionalized Polysiloxanes. Fuel Cells. (2007), 1, 40–6. 14. Woudenberg, R.C

  7. Hybrid local-order mechanism for inversion symmetry breaking

    Science.gov (United States)

    Wolpert, Emma H.; Overy, Alistair R.; Thygesen, Peter M. M.; Simonov, Arkadiy; Senn, Mark S.; Goodwin, Andrew L.

    2018-04-01

    Using classical Monte Carlo simulations, we study a simple statistical mechanical model of relevance to the emergence of polarization from local displacements on the square and cubic lattices. Our model contains two key ingredients: a Kitaev-like orientation-dependent interaction between nearest neighbors and a steric term that acts between next-nearest neighbors. Taken by themselves, each of these two ingredients is incapable of driving long-range symmetry breaking, despite the presence of a broad feature in the corresponding heat-capacity functions. Instead, each component results in a "hidden" transition on cooling to a manifold of degenerate states; the two manifolds are different in the sense that they reflect distinct types of local order. Remarkably, their intersection, i.e., the ground state when both interaction terms are included in the Hamiltonian, supports a spontaneous polarization. In this way, our study demonstrates how local-order mechanisms might be combined to break global inversion symmetry in a manner conceptually similar to that operating in the "hybrid" improper ferroelectrics. We discuss the relevance of our analysis to the emergence of spontaneous polarization in well-studied ferroelectrics such as BaTiO3 and KNbO3.

  8. An experimental and theoretical investigation of the mechanical behavior of multilayer initially curved microplates under electrostatic actuation

    KAUST Repository

    Saghir, Shahid

    2017-04-07

    We investigate the static and dynamic behavior of a multilayer clamped-free-clamped-free (CFCF) microplate, which is made of polyimide, gold, chromium, and nickel. The microplate is slightly curved away from a stationary electrode and is electrostatically actuated. The free and forced vibrations of the microplate are examined. First, we experimentally investigate the variation of the first natural frequency under the electrostatic DC load. Then, the forced dynamic behavior is investigated by applying a harmonic AC voltage superimposed to a DC voltage. Results are shown demonstrating the transition of the dynamic response of the microplate from hardening to softening as the DC voltage is changed as well the dynamic pull-in phenomenon. For theoretical model, we adopt a dynamic analog of the von-Karman governing equations accounting for initial curvature imperfection. These equations are then used to develop a reduced order model based on the Galerkin procedure to simulate the mechanical behavior of the microplate. We compare the theoretical results with experimental data and show excellent agreement among the results. We also examine the effect of the initial rise on the natural frequencies of first three symmetric-symmetric modes of the plate.

  9. Smart Tendon Actuated Flexible Actuator

    Directory of Open Access Journals (Sweden)

    Md. Masum Billah

    2015-01-01

    Full Text Available We investigate the kinematic feasibility of a tendon-based flexible parallel platform actuator. Much of the research on tendon-driven Stewart platforms is devoted either to the completely restrained positioning mechanism (CRPM or to one particular type of the incompletely restrained positioning mechanism (IRPM where the external force is provided by the gravitational pull on the platform such as in cable-suspended Stewart platforms. An IRPM-based platform is proposed which uses the external force provided by a compliant member. The compliant central column allows the configuration to achieve n DOFs with n tendons. In particular, this investigation focuses on the angular deflection of the upper platform with respect to the lower platform. The application here is aimed at developing a linkable module that can be connected to one another so as to form a “snake robot” of sorts. Since locomotion takes precedence over positioning in this application, a 3-DOF Stewart platform is adopted. For an arbitrary angular displace of the end-effector, the corresponding length of each tendon can be determined through inverse kinematics. Mathematical singularities are investigated using the traditional analytical method of defining the Jacobian.

  10. Mathematical Modelling and Parameter Identification of an Electro-Magneto-Mechanical Actuator for Vibration Control

    DEFF Research Database (Denmark)

    Darula, Radoslav; Stein, George Juraj; Kallesøe, Carsten Skovmose

    2012-01-01

    . The electric circuit is closed with a shunt resistance connected to the electromagnet. The current induced in the circuit generates additional alternating magnetic force. This force counteracts the original vibration and damps it. In this way the coupled electro-magneto-mechanical system suppresses the forced...... of the electromagnetic circuit in its various operational regimes. The parametric identification supplements mathematical derivations. The analyzed mechanical system is essentially a Single Degree-Of-Freedom (SDOF) oscillatory system augmented by magnetic force influence. The additional magnetic force is generated...... by an electromagnet with armature. The electromagnet is energized by a constant voltage source. The SDOF system is excited by a harmonic force causing vibration of the armature. Due to the reluctance variation of the air gap of the magnetic circuit alternating voltage is generated across the coil terminals...

  11. "Shape function + memory mechanism"-based hysteresis modeling of magnetorheological fluid actuators

    Science.gov (United States)

    Qian, Li-Jun; Chen, Peng; Cai, Fei-Long; Bai, Xian-Xu

    2018-03-01

    A hysteresis model based on "shape function + memory mechanism" is presented and its feasibility is verified through modeling the hysteresis behavior of a magnetorheological (MR) damper. A hysteresis phenomenon in resistor-capacitor (RC) circuit is first presented and analyzed. In the hysteresis model, the "memory mechanism" originating from the charging and discharging processes of the RC circuit is constructed by adopting a virtual displacement variable and updating laws for the reference points. The "shape function" is achieved and generalized from analytical solutions of the simple semi-linear Duhem model. Using the approach, the memory mechanism reveals the essence of specific Duhem model and the general shape function provides a direct and clear means to fit the hysteresis loop. In the frame of the structure of a "Restructured phenomenological model", the original hysteresis operator, i.e., the Bouc-Wen operator, is replaced with the new hysteresis operator. The comparative work with the Bouc-Wen operator based model demonstrates superior performances of high computational efficiency and comparable accuracy of the new hysteresis operator-based model.

  12. Mechanical performance of oil palm empty fruit bunches/jute fibres reinforced epoxy hybrid composites

    Energy Technology Data Exchange (ETDEWEB)

    Jawaid, M. [School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia); Abdul Khalil, H.P.S., E-mail: akhalilhps@gmail.com [School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia); Abu Bakar, A. [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2010-11-15

    Research highlights: {yields} Hybrid composites constituents of natural fibres show good mechanical performances. {yields} Hybridization with 20% jute fibre gives rise to sufficient modulus to composites. {yields} Outer or core material affect mechanical performance of hybrid composites. {yields} Impact strength of pure EFB composite is higher than hybrid composites. - Abstract: Oil palm empty fruit bunches (EFB)/jute fibre reinforced epoxy hybrid composites with different sequence of fibre mat arrangement such as EFB/jute/EFB and jute/EFB/jute were fabricated by hand lay-up method. The effect of layering patterns on the mechanical performance of the composites was studied. The hybrid composites are intended for engineering applications as an alternative to synthetic fibre composites. Mechanical performance of hybrid composites were evaluated and compared with the pure EFB, pure jute composites and neat epoxy using flexural and impact testing. The flexural properties of hybrid composite is higher than that of pure EFB composite with respect to the weight fraction of fibre, where as the impact strength of pure EFB composite is much higher than those of hybrid composites. The flexural results were interpreted using sandwich theory. The fracture surface morphology of the impact testing samples of the hybrid composites was performed by scanning electron microscopy (SEM).

  13. Mechanical performance of oil palm empty fruit bunches/jute fibres reinforced epoxy hybrid composites

    International Nuclear Information System (INIS)

    Jawaid, M.; Abdul Khalil, H.P.S.; Abu Bakar, A.

    2010-01-01

    Research highlights: → Hybrid composites constituents of natural fibres show good mechanical performances. → Hybridization with 20% jute fibre gives rise to sufficient modulus to composites. → Outer or core material affect mechanical performance of hybrid composites. → Impact strength of pure EFB composite is higher than hybrid composites. - Abstract: Oil palm empty fruit bunches (EFB)/jute fibre reinforced epoxy hybrid composites with different sequence of fibre mat arrangement such as EFB/jute/EFB and jute/EFB/jute were fabricated by hand lay-up method. The effect of layering patterns on the mechanical performance of the composites was studied. The hybrid composites are intended for engineering applications as an alternative to synthetic fibre composites. Mechanical performance of hybrid composites were evaluated and compared with the pure EFB, pure jute composites and neat epoxy using flexural and impact testing. The flexural properties of hybrid composite is higher than that of pure EFB composite with respect to the weight fraction of fibre, where as the impact strength of pure EFB composite is much higher than those of hybrid composites. The flexural results were interpreted using sandwich theory. The fracture surface morphology of the impact testing samples of the hybrid composites was performed by scanning electron microscopy (SEM).

  14. Hybrid controller design and verification for the METIS Cold Chopper Mechanism

    NARCIS (Netherlands)

    Huisman, Robert; Jayawardhana, Bayu; Scherpen, Jacquelien M.A.

    2014-01-01

    We discuss the design and validation of a hybrid controller for the METIS Cold Chopper Mechanism (MCCD)(1). The described control strategy has been chosen to meet the stringent performance requirements of the mechanism subject to constraints on the input.

  15. Mathematical Modelling and Parameter Identification of an Electro-Magneto-Mechanical Actuator for Vibration Control

    DEFF Research Database (Denmark)

    Darula, Radoslav; Stein, George Juraj; Kallesøe, Carsten Skovmose

    2012-01-01

    Electromechanical systems for vibration control exhibit complex non-linear behaviour. Therefore advanced mathematical tools and appropriate simplifications are required for their modelling. To properly understand the dynamics of such a non-linear system, it is necessary to identify the parameters....... The electric circuit is closed with a shunt resistance connected to the electromagnet. The current induced in the circuit generates additional alternating magnetic force. This force counteracts the original vibration and damps it. In this way the coupled electro-magneto-mechanical system suppresses the forced...

  16. Hydraulic actuator mechanism to control aircraft spoiler movements through dual input commands

    Science.gov (United States)

    Irick, S. C. (Inventor)

    1981-01-01

    An aircraft flight spoiler control mechanism is described. The invention enables the conventional, primary spoiler control system to retain its operational characteristics while accommodating a secondary input controlled by a conventional computer system to supplement the settings made by the primary input. This is achieved by interposing springs between the primary input and the spoiler control unit. The springs are selected to have a stiffness intermediate to the greater force applied by the primary control linkage and the lesser resistance offered by the spoiler control unit. Thus, operation of the primary input causes the control unit to yield before the springs, yet, operation of the secondary input, acting directly on the control unit, causes the springs to yield and absorb adjustments before they are transmitted into the primary control system.

  17. Performance of a hybrid chemical/mechanical heat pump

    Science.gov (United States)

    Silvestri, John J.; Scaringe, Robert P.; Grzyll, Lawrence R.

    1990-01-01

    The authors present the design and preliminary results of the performance of a hybrid chemical/mechanical, low-lift (20 C) heat pump. Studies have indicated that this heat pump has several advantages over the traditional single fluid vapor compression (reverse Rankine) heat pump. Included in these benefits are: 1) increased COPc due to the approximation of the cycle to the Lorenz cycle and due to the availability of the heat of solution, along with the heat of vaporization, to provide cooling; and 2) ease of variation in system cooling capacity by changing the fluid composition. The system performance is predicted for a variety of refrigerant-absorbent pairs. Cooling capacity is determined for systems operating with ammonia as the refrigerant and lithium nitrate and sodium thiocyanate as the absorbents and also with water as the refrigerant and magnesium chloride, potassium hydroxide, lithium bromide, sodium hydroxide, and sulfuric acid as the absorbents. Early indications have shown that the systems operating with water as the refrigerant operate at 2-4 times the capacity of the ammonia-refrigerant-based systems. Using existing working fluids in the proposed innovative design, a coefficient-of-performance improvement of 21 percent is possible when compared to the best vapor compression systems analyzed.

  18. Design of Mechanically Actuated Aerodynamic Braking System on a Formula Student Race Car

    Science.gov (United States)

    Muralidharan, Vivek; Balakrishnan, Abhijith; Vardhan, Vinit Ketan; Meena, Nikita; Kumar, Y. Suresh

    2018-04-01

    Every second in a racing competition counts the performance of a team against the other. Many innovative and sophisticated techniques are being employed to overcome loses in time and add to the performance of the vehicle. Especially in a car racing challenge there is more freedom to install these innovative systems to empower the car to maximum efficiency due to availability of more space. At the global spectrum there are few events which encourage such innovations. Formula Student Racing competitions are one of the global events organized by the Society of Automotive Engineers of different countries which gives opportunity to university students to build and race formula style cars. Like any other racing competitions in this high octane event having an inch over their opponents is always an advantage. Not just better acceleration and high velocities but also good deceleration is required to excel in the competition. Aerodynamic braking system is utilizing the aerodynamic drag force to create high deceleration. This mechanism can be installed on any car with spoilers with minimum modification. Being a student event great amount of care needs to be given to the safety concerns of the driver.

  19. A Novel Piezo-Actuator-Sensor Micromachine for Mechanical Characterization of Micro-Specimens

    Directory of Open Access Journals (Sweden)

    Leila Ladani

    2010-12-01

    Full Text Available Difficulties associated with testing and characterization of materials at microscale demands for new technologies and devices that are capable of measuring forces and strains at microscale. To address this issue, a novel electroactive-based micro-electro-mechanical machine is designed. The micromachine is comprised of two electroactive (piezoelectric micro-elements mounted on a rigid frame. Electrical activation of one of the elements causes it to expand and induce a stress in the intervening micro-specimen. The response of the microspecimen to the stress is measured by the deformation and thereby voltage/resistance induced in the second electro-active element. The concept is theoretically proven using analytical modeling in conjunction with non-linear, three dimensional finite element analyses for the micromachine. Correlation of the output voltage to the specimen stiffness is shown. It is also demonstrated through finite element and analytical analysis that this technique is capable of detecting non-linear behavior of materials. A characteristic curve for an isotropic specimen exhibiting linear elastic behavior is developed. Application of the proposed device in measuring coefficient of thermal expansion is explored and analytical analysis is conducted.

  20. Biological and mechanical evaluation of a Bio-Hybrid scaffold for autologous valve tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Jahnavi, S [Stem Cell and Molecular Biology Laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai, TN 600036 (India); Tissue Culture Laboratory, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Poojappura, Trivandrum, Kerala 695012 (India); Saravanan, U [Department of Civil Engineering, Indian Institute of Technology Madras, Chennai, TN 600036 (India); Arthi, N [Stem Cell and Molecular Biology Laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai, TN 600036 (India); Bhuvaneshwar, G S [Department of Engineering Design, Indian Institute of Technology Madras, Chennai, TN 600036 (India); Kumary, T V [Tissue Culture Laboratory, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Poojappura, Trivandrum, Kerala 695012 (India); Rajan, S [Madras Medical Mission, Institute of Cardio-Vascular Diseases, Mogappair, Chennai, Tamil Nadu 600037 (India); Verma, R S, E-mail: vermars@iitm.ac.in [Stem Cell and Molecular Biology Laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai, TN 600036 (India)

    2017-04-01

    Major challenge in heart valve tissue engineering for paediatric patients is the development of an autologous valve with regenerative capacity. Hybrid tissue engineering approach is recently gaining popularity to design scaffolds with desired biological and mechanical properties that can remodel post implantation. In this study, we fabricated aligned nanofibrous Bio-Hybrid scaffold made of decellularized bovine pericardium: polycaprolactone-chitosan with optimized polymer thickness to yield the desired biological and mechanical properties. CD44{sup +}, αSMA{sup +}, Vimentin{sup +} and CD105{sup −} human valve interstitial cells were isolated and seeded on these Bio-Hybrid scaffolds. Subsequent biological evaluation revealed interstitial cell proliferation with dense extra cellular matrix deposition that indicated the viability for growth and proliferation of seeded cells on the scaffolds. Uniaxial mechanical tests along axial direction showed that the Bio-Hybrid scaffolds has at least 20 times the strength of the native valves and its stiffness is nearly 3 times more than that of native valves. Biaxial and uniaxial mechanical studies on valve interstitial cells cultured Bio-Hybrid scaffolds revealed that the response along the axial and circumferential direction was different, similar to native valves. Overall, our findings suggest that Bio-Hybrid scaffold is a promising material for future development of regenerative heart valve constructs in children. - Highlights: • We report detailed biological and mechanical investigations of a Bio-Hybrid scaffold. • Optimized polymer thickness yielded desired biological and mechanical properties. • Bio-Hybrid scaffold revealed hVIC proliferation with dense ECM deposition. • Biaxial testing indicated that Bio-Hybrid scaffolds are mechanically stronger than native valves. • Bio-Hybrid scaffold is a promising material for autologous valve tissue engineering.

  1. Quantum chemical approaches: semiempirical molecular orbital and hybrid quantum mechanical/molecular mechanical techniques.

    Science.gov (United States)

    Bryce, Richard A; Hillier, Ian H

    2014-01-01

    The use of computational quantum chemical methods to aid drug discovery is surveyed. An overview of the various computational models spanning ab initio, density function theory, semiempirical molecular orbital (MO), and hybrid quantum mechanical (QM)/molecular mechanical (MM) methods is given and their strengths and weaknesses are highlighted, focussing on the challenge of obtaining the accuracy essential for them to make a meaningful contribution to drug discovery. Particular attention is given to hybrid QM/MM and semiempirical MO methods which have the potential to yield the necessary accurate predictions of macromolecular structure and reactivity. These methods are shown to have advanced the study of many aspects of substrate-ligand interactions relevant to drug discovery. Thus, the successful parametrization of semiempirical MO methods and QM/MM methods can be used to model noncovalent substrate-protein interactions, and to lead to improved scoring functions. QM/MM methods can be used in crystal structure refinement and are particularly valuable for modelling covalent protein-ligand interactions and can thus aid the design of transition state analogues. An extensive collection of examples from the areas of metalloenzyme structure, enzyme inhibition, and ligand binding affinities and scoring functions are used to illustrate the power of these techniques.

  2. Actuator concepts and mechatronics

    Science.gov (United States)

    Gilbert, Michael G.; Horner, Garnett C.

    1998-06-01

    Mechatronic design implies the consideration of integrated mechanical, electrical, and local control characteristics in electromechanical device design. In this paper, mechatronic development of actuation device concepts for active aircraft aerodynamic flow control are presented and discussed. The devices are intended to be embedded in aircraft aerodynamic surfaces to provide zero-net-momentum jets or additional flow-vorticity to control boundary layers and flow- separation. Two synthetic jet device prototypes and one vorticity-on-demand prototype currently in development are described in the paper. The aspects of actuation materials, design approaches to generating jets and vorticity, and the integration of miniaturized electronics are stressed.

  3. Mechanisms Underlying Mammalian Hybrid Sterility in Two Feline Interspecies Models.

    Science.gov (United States)

    Davis, Brian W; Seabury, Christopher M; Brashear, Wesley A; Li, Gang; Roelke-Parker, Melody; Murphy, William J

    2015-10-01

    The phenomenon of male sterility in interspecies hybrids has been observed for over a century, however, few genes influencing this recurrent phenotype have been identified. Genetic investigations have been primarily limited to a small number of model organisms, thus limiting our understanding of the underlying molecular basis of this well-documented "rule of speciation." We utilized two interspecies hybrid cat breeds in a genome-wide association study employing the Illumina 63 K single-nucleotide polymorphism array. Collectively, we identified eight autosomal genes/gene regions underlying associations with hybrid male sterility (HMS) involved in the function of the blood-testis barrier, gamete structural development, and transcriptional regulation. We also identified several candidate hybrid sterility regions on the X chromosome, with most residing in close proximity to complex duplicated regions. Differential gene expression analyses revealed significant chromosome-wide upregulation of X chromosome transcripts in testes of sterile hybrids, which were enriched for genes involved in chromatin regulation of gene expression. Our expression results parallel those reported in Mus hybrids, supporting the "Large X-Effect" in mammalian HMS and the potential epigenetic basis for this phenomenon. These results support the value of the interspecies feline model as a powerful tool for comparison to rodent models of HMS, demonstrating unique aspects and potential commonalities that underpin mammalian reproductive isolation. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Hydraulically actuated artificial muscles

    Science.gov (United States)

    Meller, M. A.; Tiwari, R.; Wajcs, K. B.; Moses, C.; Reveles, I.; Garcia, E.

    2012-04-01

    Hydraulic Artificial Muscles (HAMs) consisting of a polymer tube constrained by a nylon mesh are presented in this paper. Despite the actuation mechanism being similar to its popular counterpart, which are pneumatically actuated (PAM), HAMs have not been studied in depth. HAMs offer the advantage of compliance, large force to weight ratio, low maintenance, and low cost over traditional hydraulic cylinders. Muscle characterization for isometric and isobaric tests are discussed and compared to PAMs. A model incorporating the effect of mesh angle and friction have also been developed. In addition, differential swelling of the muscle on actuation has also been included in the model. An application of lab fabricated HAMs for a meso-scale robotic system is also presented.

  5. Electric-Pneumatic Actuator: A New Muscle for Locomotion

    OpenAIRE

    Ahmad Sharbafi, Maziar; Shin, Hirofumi; Zhao, Guoping; Hosoda, Koh; Seyfarth, Andre

    2017-01-01

    A better understanding of how actuator design supports locomotor function may help develop novel and more functional powered assistive devices or robotic legged systems. Legged robots comprise passive parts (e.g., segments, joints and connections) which are moved in a coordinated manner by actuators. In this study, we propose a novel concept of a hybrid electric-pneumatic actuator (EPA) as an enhanced variable impedance actuator (VIA). EPA is consisted of a pneumatic artificial muscle (PAM) a...

  6. Cold forging stem of total hip prosthesis with hybrid mechanical properties

    International Nuclear Information System (INIS)

    Lopes, E.S.N.; Contieri, R.J.; Cardoso, F.F.; Cremasco, A.; Button, S.T.; Caram, R.

    2010-01-01

    Type β Ti alloy is one of the most versatile groups of materials with regard to mechanical properties. Aspects such as alloying elements selection, mechanical processing and heat treatment routes empower these materials in applications where hybrid mechanical behavior is necessary. The aim of this study is to produce stems of total hip prostheses with hybrid mechanical properties using Ti-Nb alloys. Ingots were produced by using arc melting. Following, samples were subjected to specific heat treatment aiming to make cold forging. Sample characterization includes X-ray diffraction, scanning electron microscopy, Vickers hardness tests and tensile test. The experiments performed allowed to examine the effects of heat treatment parameters on the microstructure and mechanical behavior. Finally, results obtained show that the application of specific heat treatments of quenching and aging makes feasible the manufacturing of orthopedic devices with hybrid mechanical properties with regions where high mechanical strength was prioritized, while in others, low elastic modulus was the main concern. (author)

  7. Induction of osteogenic differentiation of adipose derived stem cells by microstructured nitinol actuator-mediated mechanical stress.

    Directory of Open Access Journals (Sweden)

    Sarah Strauß

    Full Text Available The development of large tissue engineered bone remains a challenge in vitro, therefore the use of hybrid-implants might offer a bridge between tissue engineering and dense metal or ceramic implants. Especially the combination of the pseudoelastic implant material Nitinol (NiTi with adipose derived stem cells (ASCs opens new opportunities, as ASCs are able to differentiate osteogenically and therefore enhance osseointegration of implants. Due to limited knowledge about the effects of NiTi-structures manufactured by selective laser melting (SLM on ASCs the study started with an evaluation of cytocompatibility followed by the investigation of the use of SLM-generated 3-dimensional NiTi-structures preseeded with ASCs as osteoimplant model. In this study we could demonstrate for the first time that osteogenic differentiation of ASCs can be induced by implant-mediated mechanical stimulation without support of osteogenic cell culture media. By use of an innovative implant design and synthesis via SLM-technique we achieved high rates of vital cells, proper osteogenic differentiation and mechanically loadable NiTi-scaffolds could be achieved.

  8. Dynamic mechanical and dielectric behavior of banana–glass hybrid fiber reinforced polyester composites.

    CSIR Research Space (South Africa)

    Pothan, LA

    2009-01-01

    Full Text Available Hybrid composites of glass and banana fiber (obtained from the pseudo stem of Musa sapientum) in polyester matrix, are subjected to dynamic mechanical analysis over a range of temperature and three different frequencies. The effect of temperature...

  9. Design of a New MR Compatible Haptic Interface with Six Actuated Degrees of Freedom

    DEFF Research Database (Denmark)

    Ergin, Mehmet Alper; Kühne, Markus; Thielscher, Axel

    2014-01-01

    Functional magnetic resonance imaging is an often adopted tool to study human motor control mechanisms. Highly controlled experiments as required by this form of analysis can be realized with haptic interfaces. Their design is challenging because of strong safety and MR compatibility requirements....... Existing MR-compatible haptic interfaces are restricted to maximum three actuated degrees of freedom. We propose an MR-compatible haptic interface with six actuated degrees of freedom to be able to study human brain mechanisms of natural pick-and-place movements including arm transport. In this work, we...... present its mechanical design, kinematic and dynamic model, as well as report on its model-based characterization. A novel hybrid control scheme for the employed ultrasonic motors is introduced. Preliminary MR compatibility tests based on one complete actuator-sensor module are performed. No measurable...

  10. Mechanically Robust Magnetic Carbon Nanotube Papers Prepared with CoFe2O4 Nanoparticles for Electromagnetic Interference Shielding and Magnetomechanical Actuation.

    Science.gov (United States)

    Lim, Guh-Hwan; Woo, Seongwon; Lee, Hoyoung; Moon, Kyoung-Seok; Sohn, Hiesang; Lee, Sang-Eui; Lim, Byungkwon

    2017-11-22

    The introduction of inorganic nanoparticles into carbon nanotube (CNT) papers can provide a versatile route to the fabrication of CNT papers with diverse functionalities, but it may lead to a reduction in their mechanical properties. Here, we describe a simple and effective strategy for the fabrication of mechanically robust magnetic CNT papers for electromagnetic interference (EMI) shielding and magnetomechanical actuation applications. The magnetic CNT papers were produced by vacuum filtration of an aqueous suspension of CNTs, CoFe 2 O 4 nanoparticles, and poly(vinyl alcohol) (PVA). PVA plays a critical role in enhancing the mechanical strength of CNT papers. The magnetic CNT papers containing 73 wt % of CoFe 2 O 4 nanoparticles exhibited high mechanical properties with Young's modulus of 3.2 GPa and tensile strength of 30.0 MPa. This magnetic CNT paper was successfully demonstrated as EMI shielding paper with shielding effectiveness of ∼30 dB (99.9%) in 0.5-1.0 GHz, and also as a magnetomechanical actuator in an audible frequency range from 200 to 20 000 Hz.

  11. Effects of fibre orientation on mechanical properties of hybrid ...

    Indian Academy of Sciences (India)

    Administrator

    The usage of plant fibre cannot alone satisfy all the needs of the composites. Hence, introduction of hybrid ... density, low cost, consumes low energy, distributed worldwide, neutral to CO2, no abrasion to machining, no health risk when inhaled ...

  12. Hybridity, coping mechanisms, and academic performance management: Comparing three countries

    NARCIS (Netherlands)

    Teelken, J.C.

    2015-01-01

    Recent developments in the higher education sectors of the Netherlands, Sweden, and the UK concerning accountability and performance measurement in research have resulted in a variety of responses from individual academics. The concept of hybridity enables us to explain these developments over time.

  13. Designing and testing lightweight shoulder prostheses with hybrid actuators for movements involved in typical activities of daily living and impact absorption.

    Science.gov (United States)

    Sekine, Masashi; Kita, Kahori; Yu, Wenwei

    2015-01-01

    Unlike forearm amputees, transhumeral amputees have residual stumps that are too small to provide a sufficient range of operation for their prosthetic parts to perform usual activities of daily living. Furthermore, it is difficult for small residual stumps to provide sufficient impact absorption for safe manipulation in daily living, as intact arms do. Therefore, substitution of upper limb function in transhumeral amputees requires a sufficient range of motion and sufficient viscoelasticity for shoulder prostheses under critical weight and dimension constraints. We propose the use of two different types of actuators, ie, pneumatic elastic actuators (PEAs) and servo motors. PEAs offer high power-to-weight performance and have intrinsic viscoelasticity in comparison with motors or standard industrial pneumatic cylinder actuators. However, the usefulness of PEAs in large working spaces is limited because of their short strokes. Servo motors, in contrast, can be used to achieve large ranges of motion. In this study, the relationship between the force and stroke of PEAs was investigated. The impact absorption of both types of actuators was measured using a single degree-of-freedom prototype to evaluate actuator compliance for safety purposes. Based on the fundamental properties of the actuators identified, a four degree-of-freedom robotic arm is proposed for prosthetic use. The configuration of the actuators and functional parts was designed to achieve a specified range of motion and torque calculated from the results of a simulation of typical movements performed in usual activities of daily living. Our experimental results showed that the requirements for the shoulder prostheses could be satisfied.

  14. Mechanisms of Transmission Ratio Distortion at Hybrid Sterility Loci Within and Between Mimulus Species

    Directory of Open Access Journals (Sweden)

    Rachel E. Kerwin

    2017-11-01

    Full Text Available Hybrid incompatibilities are a common correlate of genomic divergence and a potentially important contributor to reproductive isolation. However, we do not yet have a detailed understanding of how hybrid incompatibility loci function and evolve within their native species, or why they are dysfunctional in hybrids. Here, we explore these issues for a well-studied, two-locus hybrid incompatibility between hybrid male sterility 1 (hms1 and hybrid male sterility 2 (hms2 in the closely related yellow monkeyflower species Mimulus guttatus and M. nasutus. By performing reciprocal backcrosses with introgression lines (ILs, we find evidence for gametic expression of the hms1-hms2 incompatibility. Surprisingly, however, hybrid transmission ratios at hms1 do not reflect this incompatibility, suggesting that additional mechanisms counteract the effects of gametic sterility. Indeed, our backcross experiment shows hybrid transmission bias toward M. guttatus through both pollen and ovules, an effect that is particularly strong when hms2 is homozygous for M. nasutus alleles. In contrast, we find little evidence for hms1 transmission bias in crosses within M. guttatus, providing no indication of selfish evolution at this locus. Although we do not yet have sufficient genetic resolution to determine if hybrid sterility and transmission ratio distortion (TRD map to the same loci, our preliminary fine-mapping uncovers a genetically independent hybrid lethality system involving at least two loci linked to hms1. This fine-scale dissection of TRD at hms1 and hms2 provides insight into genomic differentiation between closely related Mimulus species and reveals multiple mechanisms of hybrid dysfunction.

  15. Mechanisms of Transmission Ratio Distortion at Hybrid Sterility Loci Within and Between Mimulus Species.

    Science.gov (United States)

    Kerwin, Rachel E; Sweigart, Andrea L

    2017-11-06

    Hybrid incompatibilities are a common correlate of genomic divergence and a potentially important contributor to reproductive isolation. However, we do not yet have a detailed understanding of how hybrid incompatibility loci function and evolve within their native species, or why they are dysfunctional in hybrids. Here, we explore these issues for a well-studied, two-locus hybrid incompatibility between hybrid male sterility 1 ( hms1 ) and hybrid male sterility 2 ( hms2 ) in the closely related yellow monkeyflower species Mimulus guttatus and M. nasutus By performing reciprocal backcrosses with introgression lines (ILs), we find evidence for gametic expression of the hms1-hms2 incompatibility. Surprisingly, however, hybrid transmission ratios at hms1 do not reflect this incompatibility, suggesting that additional mechanisms counteract the effects of gametic sterility. Indeed, our backcross experiment shows hybrid transmission bias toward M. guttatus through both pollen and ovules, an effect that is particularly strong when hms2 is homozygous for M. nasutus alleles. In contrast, we find little evidence for hms1 transmission bias in crosses within M. guttatus , providing no indication of selfish evolution at this locus. Although we do not yet have sufficient genetic resolution to determine if hybrid sterility and transmission ratio distortion (TRD) map to the same loci, our preliminary fine-mapping uncovers a genetically independent hybrid lethality system involving at least two loci linked to hms1 This fine-scale dissection of TRD at hms1 and hms2 provides insight into genomic differentiation between closely related Mimulus species and reveals multiple mechanisms of hybrid dysfunction. Copyright © 2017 Kerwin and Sweigart.

  16. Effect of layering sequence and chemical treatment on the mechanical properties of woven kenaf–aramid hybrid laminated composites

    International Nuclear Information System (INIS)

    Yahaya, R.; Sapuan, S.M.; Jawaid, M.; Leman, Z.; Zainudin, E.S.

    2015-01-01

    Highlights: • The mechanical properties of woven kenaf/Kevlar hybrid composites were analysed. • The layering sequences affect the mechanical properties of hybrid composites. • Treated kenaf improves the mechanical properties of hybrid composites. - Abstract: This work aims to evaluate the effect of layering sequence and chemical treatment on mechanical properties of woven kenaf–Kevlar composites. Woven kenaf–aramid hybrid laminated composites fabricated through hand lay-up techniques by arranging woven kenaf and Kevlar fabrics in different layering sequences and by using treated kenaf mat. To evaluate the effect of chemical treatment on hybrid composites, the woven kenaf mat was treated with 6% sodium hydroxide (NaOH) diluted solution and compared mechanical properties with untreated kenaf hybrid composites. Results shows that the tensile properties of hybrid composites improved in 3-layer composites compared to 4-layer composites. Hybrid composite with Kevlar as outer layers display a better mechanical properties as compared to other hybrid composites. Tensile and flexural properties of treated hybrid composites are better than non-treated hybrid composites. The fractured surface of hybrid composites was investigated by scanning electron microscopy. This study is a part of exploration of potential application of the hybrid composite in high velocity impact application

  17. A bidirectional shape memory alloy folding actuator

    International Nuclear Information System (INIS)

    Paik, Jamie K; Wood, Robert J

    2012-01-01

    This paper presents a low-profile bidirectional folding actuator based on annealed shape memory alloy sheets applicable for meso- and microscale systems. Despite the advantages of shape memory alloys—high strain, silent operation, and mechanical simplicity—their application is often limited to unidirectional operation. We present a bidirectional folding actuator that produces two opposing 180° motions. A laser-patterned nickel alloy (Inconel 600) heater localizes actuation to the folding sections. The actuator has a thin ( < 1 mm) profile, making it appropriate for use in robotic origami. Various design parameters and fabrication variants are described and experimentally explored in the actuator prototype. (paper)

  18. Mechanical analysis of CFRP-steel hybrid composites considering the interfacial adhesion

    Science.gov (United States)

    Jang, Jinhyeok; Sung, Minchang; Han, Sungjin; Shim, Wonbo; Yu, Woong-Ryeol

    2017-10-01

    Recently, hybrid composites of carbon fiber reinforced plastics (CFRP) and steel have attracted great attention from automotive engineers due to their high potential for lightweight and multi-materials structures. Interestingly, such hybrid composites have demonstrated increased breaking strain, i.e., the breaking strain of CFRP in the hybrid was larger than that of single CFRP. As such the mechanical properties of hybrid composites could not be calculated using the rule of mixture. In addition, such increase is strongly dependent on the adhesion between CFRP and steel. In this study, a numerical analysis model was built to investigate the mechanism behind increased breaking strain of CFRP in the hybrid structure. Using cohesive zone model, the adhesion between CFRP and steel was effectively considered. The numerical results showed that the simulated mechanical behavior of the hybrid composites did not change as much as observed in experimental as the interfacial adhesion varied. We will investigate this discrepancy in detail and will report new analysis method suitable for CFRP and steel hybrid composites.

  19. Mechanical Properties of Graphene Nanoplatelet/Carbon Fiber/Epoxy Hybrid Composites: Multiscale Modeling and Experiments

    Science.gov (United States)

    Hadden, C. M.; Klimek-McDonald, D. R.; Pineda, E. J.; King, J. A.; Reichanadter, A. M.; Miskioglu, I.; Gowtham, S.; Odegard, G. M.

    2015-01-01

    Because of the relatively high specific mechanical properties of carbon fiber/epoxy composite materials, they are often used as structural components in aerospace applications. Graphene nanoplatelets (GNPs) can be added to the epoxy matrix to improve the overall mechanical properties of the composite. The resulting GNP/carbon fiber/epoxy hybrid composites have been studied using multiscale modeling to determine the influence of GNP volume fraction, epoxy crosslink density, and GNP dispersion on the mechanical performance. The hierarchical multiscale modeling approach developed herein includes Molecular Dynamics (MD) and micromechanical modeling, and it is validated with experimental testing of the same hybrid composite material system. The results indicate that the multiscale modeling approach is accurate and provides physical insight into the composite mechanical behavior. Also, the results quantify the substantial impact of GNP volume fraction and dispersion on the transverse mechanical properties of the hybrid composite, while the effect on the axial properties is shown to be insignificant.

  20. Mechanical Properties of Graphene Nanoplatelet Carbon Fiber Epoxy Hybrid Composites: Multiscale Modeling and Experiments

    Science.gov (United States)

    Hadden, Cameron M.; Klimek-McDonald, Danielle R.; Pineda, Evan J.; King, Julie A.; Reichanadter, Alex M.; Miskioglu, Ibrahim; Gowtham, S.; Odegard, Gregory M.

    2015-01-01

    Because of the relatively high specific mechanical properties of carbon fiber/epoxy composite materials, they are often used as structural components in aerospace applications. Graphene nanoplatelets (GNPs) can be added to the epoxy matrix to improve the overall mechanical properties of the composite. The resulting GNP/carbon fiber/epoxy hybrid composites have been studied using multiscale modeling to determine the influence of GNP volume fraction, epoxy crosslink density, and GNP dispersion on the mechanical performance. The hierarchical multiscale modeling approach developed herein includes Molecular Dynamics (MD) and micromechanical modeling, and it is validated with experimental testing of the same hybrid composite material system. The results indicate that the multiscale modeling approach is accurate and provides physical insight into the composite mechanical behavior. Also, the results quantify the substantial impact of GNP volume fraction and dispersion on the transverse mechanical properties of the hybrid composite, while the effect on the axial properties is shown to be insignificant.

  1. Hybrid real-code ant colony optimisation for constrained mechanical design

    Science.gov (United States)

    Pholdee, Nantiwat; Bureerat, Sujin

    2016-01-01

    This paper proposes a hybrid meta-heuristic based on integrating a local search simplex downhill (SDH) method into the search procedure of real-code ant colony optimisation (ACOR). This hybridisation leads to five hybrid algorithms where a Monte Carlo technique, a Latin hypercube sampling technique (LHS) and a translational propagation Latin hypercube design (TPLHD) algorithm are used to generate an initial population. Also, two numerical schemes for selecting an initial simplex are investigated. The original ACOR and its hybrid versions along with a variety of established meta-heuristics are implemented to solve 17 constrained test problems where a fuzzy set theory penalty function technique is used to handle design constraints. The comparative results show that the hybrid algorithms are the top performers. Using the TPLHD technique gives better results than the other sampling techniques. The hybrid optimisers are a powerful design tool for constrained mechanical design problems.

  2. Polypyrrole Actuators for Tremor Suppression

    DEFF Research Database (Denmark)

    Skaarup, Steen; Mogensen, Naja; Bay, Lasse

    2003-01-01

    Neurological tremor affecting limbs can be divided into at least 6 different types with frequencies ranging from 2 to about 20 Hz. In order to alleviate the symptoms by suppressing the tremor, sensing and actuation systems able to perform at these frequencies are needed. Electroactive polymers...... exemplify 'soft actuator' technology that may be especially suitable for use in conjunction with human limbs. The electrochemical and mechanical properties of polypyrrole dodecyl benzene sulphonate actuator films have been studied with this application in mind. The results show that the time constants...

  3. Biological and mechanical evaluation of a Bio-Hybrid scaffold for autologous valve tissue engineering.

    Science.gov (United States)

    Jahnavi, S; Saravanan, U; Arthi, N; Bhuvaneshwar, G S; Kumary, T V; Rajan, S; Verma, R S

    2017-04-01

    Major challenge in heart valve tissue engineering for paediatric patients is the development of an autologous valve with regenerative capacity. Hybrid tissue engineering approach is recently gaining popularity to design scaffolds with desired biological and mechanical properties that can remodel post implantation. In this study, we fabricated aligned nanofibrous Bio-Hybrid scaffold made of decellularized bovine pericardium: polycaprolactone-chitosan with optimized polymer thickness to yield the desired biological and mechanical properties. CD44 + , αSMA + , Vimentin + and CD105 - human valve interstitial cells were isolated and seeded on these Bio-Hybrid scaffolds. Subsequent biological evaluation revealed interstitial cell proliferation with dense extra cellular matrix deposition that indicated the viability for growth and proliferation of seeded cells on the scaffolds. Uniaxial mechanical tests along axial direction showed that the Bio-Hybrid scaffolds has at least 20 times the strength of the native valves and its stiffness is nearly 3 times more than that of native valves. Biaxial and uniaxial mechanical studies on valve interstitial cells cultured Bio-Hybrid scaffolds revealed that the response along the axial and circumferential direction was different, similar to native valves. Overall, our findings suggest that Bio-Hybrid scaffold is a promising material for future development of regenerative heart valve constructs in children. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Bistable microelectromechanical actuator

    Science.gov (United States)

    Fleming, James G.

    1999-01-01

    A bistable microelectromechanical (MEM) actuator is formed on a substrate and includes a stressed membrane of generally rectangular shape that upon release assumes a curvilinear cross-sectional shape due to attachment at a midpoint to a resilient member and at opposing edges to a pair of elongate supports. The stressed membrane can be electrostatically switched between a pair of mechanical states having mirror-image symmetry, with the MEM actuator remaining in a quiescent state after a programming voltage is removed. The bistable MEM actuator according to various embodiments of the present invention can be used to form a nonvolatile memory element, an optical modulator (with a pair of mirrors supported above the membrane and moving in synchronism as the membrane is switched), a switchable mirror (with a single mirror supported above the membrane at the midpoint thereof) and a latching relay (with a pair of contacts that open and close as the membrane is switched). Arrays of bistable MEM actuators can be formed for applications including nonvolatile memories, optical displays and optical computing.

  5. Materials selection and design of microelectrothermal bimaterial actuators

    OpenAIRE

    Prasanna, S.; Spearing, S.M.

    2007-01-01

    A common form of MEMS actuator is a thermally actuated bimaterial, which is easy to fabricate by surface micromachining and permits out of plane actuation, which is otherwise difficult to achieve. This paper presents an analytical framework for the design of such microelectrothermal bimaterial actuators. Mechanics relationships for a cantilever bimaterial strip subjected to a uniform temperature were applied to obtain expressions for performance metrics for the actuator, i.e., maximum work/vo...

  6. Configuration Synthesis of Novel Series-Parallel Hybrid Transmission Systems with Eight-Bar Mechanisms

    Directory of Open Access Journals (Sweden)

    Ngoc-Tan Hoang

    2017-07-01

    Full Text Available This paper presents a design approach for the configuration synthesis of series-parallel hybrid transmissions with eight-bar mechanisms. The final design consists of 54 mechanisms with eight members and twelve joints including a simple planetary gear train (PGT and a double planet PGT. Then, by using the techniques of power and clutch arrangements, new series-parallel hybrid transmissions are synthesized. The power arrangement process generates 97 clutchless hybrid systems. The clutch arrangement process generates 100 corresponding series-parallel transmissions. To demonstrate the feasibility of the synthesized configurations, a new hybrid transmission is selected as an example to analyze the working principle with operation modes and power flow paths.

  7. Thermally actuated linkage arrangement

    International Nuclear Information System (INIS)

    Anderson, P.M.

    1981-01-01

    A reusable thermally actuated linkage arrangement includes a first link member having a longitudinal bore therein adapted to receive at least a portion of a second link member therein, the first and second members being sized to effect an interference fit preventing relative movement there-between at a temperature below a predetermined temperature. The link members have different coefficients of thermal expansion so that when the linkage is selectively heated by heating element to a temperature above the predetermined temperature, relative longitudinal and/or rotational movement between the first and second link members is enabled. Two embodiments of a thermally activated linkage are disclosed which find particular application in actuators for a grapple head positioning arm in a nuclear reactor fuel handling mechanism to facilitate back-up safety retraction of the grapple head independently from the primary fuel handling mechanism drive system. (author)

  8. Driving and damping mechanisms in hybrid pressure-gravity modes pulsators

    Energy Technology Data Exchange (ETDEWEB)

    Dupret, M A [Observatoire de Paris, LESIA, CNRS UMR 8109, 5 place J. Janssen, 92195 Meudon (France); Miglio, A; Montalban, J; Noels, A [Institut d' Astrophysique et Geophysique, Universite de Liege (Belgium); Grigahcene, A [CRAAG - Algiers Observatory BP 63 Bouzareah 16340, Algiers (Algeria)], E-mail: MA.dupret@obspm.fr

    2008-10-15

    We study the energetic aspects of hybrid pressure-gravity modes pulsations. The case of hybrid {beta} Cephei-SPB pulsators is considered with special attention. In addition to the already known sensitivity of the driving mechanism to the heavy elements mixture (mainly the iron abundance), we show that the characteristics of the propagation and evanescent regions play also a major role, determining the extension of the stable gap in the frequency domain between the unstable low order pressure and high order gravity modes. Finally, we consider the case of hybrid {delta} Sct-{gamma} Dor pulsators.

  9. Mechanical Characterization of Baslat Based Natural Hybrid Composites for Aerospace Applications

    Science.gov (United States)

    Alexander, J.; Elphej Churchill, S. J.

    2017-05-01

    Advanced composites have attracted aircraft designers due to its high strength to weight ratio, high stiffness to weight ratio, tailoring properties, hybridization of opposites etc. Moreover the cost reduction is also another important requirement of structural components. Basalt fibers are new entry in structural field which has excellent properties more or less equivalent to GFRP composites. Using these basalt fibres, new hybrid composites were developed by combining basalt fibres with natural fibres. The mechanical and thermal properties were determined and compared with BFRP and GFRP composites. Results proved that hybrid composites have some good qualities.

  10. Research on Braking Stability of Electro-mechanical Hybrid Braking System in Electric Vehicles

    OpenAIRE

    Ji, Fenzhu; Tian, Mi

    2010-01-01

    For the electro-mechanical hybrid braking system, which is composed of electric brake and general friction brake, the models of electric braking force, total braking force and the utilization adhesion coefficient for front and rear axles were established based on the analysis of braking torque distribution. The variation relationship between electric braking force and friction braking force in different braking intensity was calculated and analyzed with the paralleled-hybridized braking contr...

  11. Hybrid spin-nanomechanics with single spins in diamond mechanical oscillators

    OpenAIRE

    Barfuss, Arne

    2017-01-01

    Hybrid spin-oscillator systems, formed by single spins coupled to mechanical oscillators, have attracted ever-increasing attention over the past few years, triggered largely by the prospect of employing such devices as high-performance nanoscale sensors or transducers in multi-qubit networks. Provided the spin-oscillator coupling is strong and robust, such systems can even serve as test-beds for studying macroscopic objects in the quantum regime. In this thesis we present a novel hybrid sp...

  12. 10–25 GHz frequency reconfigurable MEMS 5-bit phase shifter using push–pull actuator based toggle mechanism

    International Nuclear Information System (INIS)

    Dey, Sukomal; Koul, Shiban K

    2015-01-01

    This paper presents a frequency tunable 5-bit true-time-delay digital phase shifter using radio frequency microelectromechanical system (RF MEMS) technology. The phase shifter is based on the distributed MEMS transmission line (DMTL) concept utilizing a MEMS varactor. The main source of frequency tuning in this work is a bridge actuation mechanism followed by capacitance variation. Two stages of actuation mechanisms (push and pull) are used to achieve a 2:1 tuning ratio. Accurate control of the actuation voltage between the pull to push stages contributes differential phase shift over the band of interest. The functional behavior of the push–pull actuation over the phase shifter application is theoretically established, experimentally investigated and validated with simulation. The phase shifter is fabricated monolithically using a gold based surface micromachining process on an alumina substrate. The individual primary phase-bits (11.25°/22.5°/45°/90°/180°) that are the fundamental building blocks of the complete 5-bit phase shifter are designed, fabricated and experimentally characterized from 10–25 GHz for specific applications. Finally, the complete 5-bit phase shifter demonstrates an average phase error of 4.32°, 2.8°, 1° and 1.58°, an average insertion loss of 3.76, 4.1, 4.2 and 4.84 dB and an average return loss of 11.7, 12, 14 and 11.8 dB at 10, 12, 17.2 and 25 GHz, respectively. To the best of the authors’ knowledge, this is the first reported band tunable stand alone 5-bit phase shifter in the literature which can work over the large spectrum for different applications. The total area of the 5-bit phase shifter is 15.6 mm 2 . Furthermore, the cold-switched reliability of the unit cell and the complete 5-bit MEMS phase shifter are extensively investigated and presented. (paper)

  13. On the Mechanism of Berberine-INF55 (5-Nitro-2-phenylindole) Hybrid Antibacterials.

    Science.gov (United States)

    Dolla, Naveen K; Chen, Chao; Larkins-Ford, Jonah; Rajamuthiah, Rajmohan; Jagadeesan, Sakthimala; Conery, Annie L; Ausubel, Frederick M; Mylonakis, Eleftherios; Bremner, John B; Lewis, Kim; Kelso, Michael J

    Berberine-INF55 hybrids are a promising class of antibacterials that combine berberine and the NorA multidrug resistance pump inhibitor INF55 (5-nitro-2-phenylindole) together in one molecule via a chemically stable linkage. Previous studies demonstrated the potential of these compounds for countering efflux-mediated antibacterial drug resistance but they didn't establish whether the compounds function as originally intended, i.e. with the berberine moiety providing antibacterial activity and the attached INF55 component independently blocking multidrug resistance pumps, thereby enhancing the activity of berberine by reducing its efflux. We hypothesised that if the proposed mechanism is correct, then hybrids carrying more potent INF55 pump inhibitor structures should show enhanced antibacterial effects relative to those bearing weaker inhibitors. Two INF55 analogues showing graded reductions in NorA inhibitory activity compared with INF55 were identified and their corresponding berberine-INF55 hybrids carrying equivalent INF55 inhibitor structures synthesised. Multiple assays comparing the antibacterial effects of the hybrids and their corresponding berberine-INF55 analogue combinations showed that the three hybrids all show very similar activities, leading us to conclude that the antibacterial mechanism(s) of berberine-INF55 hybrids is different from berberine-INF55 combinations.

  14. Thermally Actuated Hydraulic Pumps

    Science.gov (United States)

    Jones, Jack; Ross, Ronald; Chao, Yi

    2008-01-01

    Thermally actuated hydraulic pumps have been proposed for diverse applications in which direct electrical or mechanical actuation is undesirable and the relative slowness of thermal actuation can be tolerated. The proposed pumps would not contain any sliding (wearing) parts in their compressors and, hence, could have long operational lifetimes. The basic principle of a pump according to the proposal is to utilize the thermal expansion and contraction of a wax or other phase-change material in contact with a hydraulic fluid in a rigid chamber. Heating the chamber and its contents from below to above the melting temperature of the phase-change material would cause the material to expand significantly, thus causing a substantial increase in hydraulic pressure and/or a substantial displacement of hydraulic fluid out of the chamber. Similarly, cooling the chamber and its contents from above to below the melting temperature of the phase-change material would cause the material to contract significantly, thus causing a substantial decrease in hydraulic pressure and/or a substantial displacement of hydraulic fluid into the chamber. The displacement of the hydraulic fluid could be used to drive a piston. The figure illustrates a simple example of a hydraulic jack driven by a thermally actuated hydraulic pump. The pump chamber would be a cylinder containing encapsulated wax pellets and containing radial fins to facilitate transfer of heat to and from the wax. The plastic encapsulation would serve as an oil/wax barrier and the remaining interior space could be filled with hydraulic oil. A filter would retain the encapsulated wax particles in the pump chamber while allowing the hydraulic oil to flow into and out of the chamber. In one important class of potential applications, thermally actuated hydraulic pumps, exploiting vertical ocean temperature gradients for heating and cooling as needed, would be used to vary hydraulic pressures to control buoyancy in undersea research

  15. Actuators for smart applications

    NARCIS (Netherlands)

    Paternoster, Alexandre; de Boer, Andries; Loendersloot, Richard; Akkerman, Remko; D. Brei,; M. Frecker,

    2010-01-01

    Actuator manufacturers are developing promising technologies which meet high requirements in performance, weight and power consumption. Conventionally, actuators are characterized by their displacement and load performance. This hides the dynamic aspects of those actuation solutions. Work per weight

  16. Correlation between Mechanical Behavior and Actuator-type Performance of Ni-Ti-Pd High-temperature Shape Memory Alloys

    Science.gov (United States)

    Bigelow, Glen S.; Padula, Santo A., II; Garg, Anita; Noebe, Ronald D.

    2007-01-01

    High-temperature shape memory alloys in the NiTiPd system are being investigated as lower cost alternatives to NiTiPt alloys for use in compact solid-state actuators for the aerospace, automotive, and power generation industries. A range of ternary NiTiPd alloys containing 15 to 46 at.% Pd has been processed and actuator mimicking tests (thermal cycling under load) were used to measure transformation temperatures, work behavior, and dimensional stability. With increasing Pd content, the work output of the material decreased, while the amount of permanent strain resulting from each load-biased thermal cycle increased. Monotonic isothermal tension testing of the high-temperature austenite and low temperature martensite phases was used to partially explain these behaviors, where a mismatch in yield strength between the austenite and martensite phases was observed at high Pd levels. Moreover, to further understand the source of the permanent strain at lower Pd levels, strain recovery tests were conducted to determine the onset of plastic deformation in the martensite phase. Consequently, the work behavior and dimensional stability during thermal cycling under load of the various NiTiPd alloys is discussed in relation to the deformation behavior of the materials as revealed by the strain recovery and monotonic tension tests.

  17. Adsorption mechanism of magnetically separable Fe_3O_4/graphene oxide hybrids

    International Nuclear Information System (INIS)

    Ouyang, Ke; Zhu, Chuanhe; Zhao, Ya; Wang, Leichao; Xie, Shan; Wang, Qun

    2015-01-01

    Graphical abstract: A recyclable Fe_3O_4/graphene oxide (GO) magnetic hybrid was successfully synthesized via a facile one-pot polylol approach and exhibited an effective adsorption of BPA in aqueous solution. - Highlights: • Magnetically separable Fe_3O_4/GO hybrids were synthesized via a facile one-pot polylol approach. • The Fe_3O_4/GO hybrid could be easily recovered and met the need of magnetic separation, exhibiting excellent reproducibility and reusability. • The hybrids showed excellent adsorption ability for bisphenol A in aqueous solution. • The effect of pH value, temperature and coexisting ions on the adsorption was studied. • π–π interactions were postulated to be the primary mechanisms of adsorption of BPA on Fe_3O_4/GO hybrids. - Abstract: A reclaimable Fe_3O_4/graphene oxide (GO) magnetic hybrid was successfully synthesized via a facile one-pot polyol approach and employed as a recyclable adsorbent for Bisphenol A (BPA) in aqueous solutions. The maximum adsorption capacity (q_m) of the Fe_3O_4/GO hybrid for BPA was 72.80 mg/g at 273 K. The kinetics of the adsorption process and the adsorption isotherm data were fitted using the Freundlich equation and a pseudo-second-order kinetic model. The results of the thermodynamic parameters ΔH°, ΔS° and ΔG° showed that the adsorption process was exothermic and spontaneous. Furthermore, the reusability of the samples was investigated, and the results indicated that the samples exhibited high stability. The magnetic characterization demonstrated that hybrids were superparamagnetic and could be recovered conveniently by magnetic separation. The strong π–π interaction was determined to be the predominant driving force behind the adsorption of BPA onto the Fe_3O_4/GO hybrid. Therefore, the Fe_3O_4/GO hybrid could be regarded as a potential adsorbent for wastewater treatment and purification processes.

  18. Low temperature nickel titanium iron shape memory alloys: Actuator engineering and investigation of deformation mechanisms using in situ neutron diffraction at Los Alamos National Laboratory

    Science.gov (United States)

    Krishnan, Vinu B.

    Shape memory alloys are incorporated as actuator elements due to their inherent ability to sense a change in temperature and actuate against external loads by undergoing a shape change as a result of a temperature-induced phase transformation. The cubic so-called austenite to the trigonal so-called R-phase transformation in NiTiFe shape memory alloys offers a practical temperature range for actuator operation at low temperatures, as it exhibits a narrow temperature-hysteresis with a desirable fatigue response. Overall, this work is an investigation of selected science and engineering aspects of low temperature NiTiFe shape memory alloys. The scientific study was performed using in situ neutron diffraction measurements at the newly developed low temperature loading capability on the Spectrometer for Materials Research at Temperature and Stress (SMARTS) at Los Alamos National Laboratory and encompasses three aspects of the behavior of Ni46.8Ti50Fe3.2 at 92 K (the lowest steady state temperature attainable with the capability). First, in order to study deformation mechanisms in the R-phase in NiTiFe, measurements were performed at a constant temperature of 92 K under external loading. Second, with the objective of examining NiTiFe in one-time, high-stroke, actuator applications (such as in safety valves), a NiTiFe sample was strained to approximately 5% (the R-phase was transformed to B19' phase in the process) at 92 K and subsequently heated to full strain recovery under a load. Third, with the objective of examining NiTiFe in cyclic, low-stroke, actuator applications (such as in cryogenic thermal switches), a NiTiFe sample was strained to 1% at 92 K and subsequently heated to full strain recovery under load. Neutron diffraction spectra were recorded at selected time and stress intervals during these experiments. The spectra were subsequently used to obtain quantitative information related to the phase-specific strain, texture and phase fraction evolution using the

  19. Design optimization of a linear actuator

    DEFF Research Database (Denmark)

    Rechenbach, B.; Willatzen, Morten; Preisler, K. Lorenzen

    2013-01-01

    The mechanical contacting of a dielectric elastomer actuator is investigated. The actuator is constructed by coiling the dielectric elastomer around two parallel metal rods, similar to a rubber band stretched by two index fingers. The goal of this paper is to design the geometry and the mechanical...

  20. A low-power-consumption out-of-Plane electrothermal actuator

    OpenAIRE

    Girbau Sala, David; Llamas Morote, Marco Antonio; Casals Terré, Jasmina; Simó Selvas, Francisco Javier; Pradell i Cara, Lluís; Lázaro Guillén, Antoni

    2007-01-01

    This paper proposes a new vertical electrothermal actuator. It can be considered as a hybrid between the traditional in-plane buckle-beam actuator and the vertical hot-cold actuator. It is here referred to as vertical buckle beam. At identical dimensional and bias conditions, it features a displacement larger than that of other vertical electrothermal actuators proposed so far in the literature. The actuator performance is demonstrated by means of an analytical model along with finite-element...

  1. Mechanical properties of hybrid SiC/CNT filled toughened epoxy nanocomposite

    Science.gov (United States)

    Ratim, S.; Ahmad, S.; Bonnia, N. N.; Yahaya, Sabrina M.

    2018-01-01

    Mechanical properties of epoxy nanocomposites filled single filler have been extensively studied by various researchers. However, there are not much discovery on the behavior of hybrid nanocomposite. In this study, single and hybrid nanocomposites of toughened epoxy filled CNT/SiC nanoparticles were investigated. The hybrid nanocomposites samples were prepared by combining CNT and SiC nanoparticles in toughened epoxy matrix via mechanical stirring method assisted with ultrasonic cavitations. Epoxy resin and liquid epoxidized natural rubber (LENR) mixture were first blend prior to the addition of nanofillers. Then, the curing process of the nanocomposite samples were conducted by compression molding technique at 130°C for 2 hours. The purpose of this study is to investigate the hybridization effect of CNT and SiC nanoparticles on mechanical properties toughened epoxy matrix. The total loading of single and hybrid nanofillers were fixed to 4% volume are 0, 4C, 4S, 3S1C, 2S2C, and 1S3C. Mechanical properties of hybrid composites show that the highest value of tensile strength achieved by 3S1C sample at about 7% increment and falls between their single composite values. Meanwhile, the stiffness of the same sample is significantly increased at about 31% of the matrix. On the other hand, a highest flexural property is obtained by 1S3C sample at about 20% increment dominated by CNT content. However, the impact strength shows reduction trend with the addition of SiC and CNT into the matrix. The hybridization of SiC and CNT show highest value in sample 1S3C at about 3.37 kJ/m2 of impact energy absorbed. FESEM micrograph have confirmed that better distributions and interaction observed between SiC nanoparticles and matrix compared to CNT, which contributed to higher tensile strength and modulus.

  2. Hybridization experiments indicate incomplete reproductive isolating mechanism between Fasciola hepatica and Fasciola gigantica.

    Science.gov (United States)

    Itagaki, T; Ichinomiya, M; Fukuda, K; Fusyuku, S; Carmona, C

    2011-09-01

    Experiments on hybridization between Fasciola hepatica and Fasciola gigantica were carried out to clarify whether a reproductive isolating mechanism appears between the two Fasciola species. Molecular evidence for hybridization was based on the DNA sequence of the internal transcribed spacer 1 (ITS1) region in nuclear ribosomal DNA, which differs between the species. The results suggested that there were not pre-mating but post-mating isolating mechanisms between the two species. However, viable adults of the hybrids F1 and F2 were produced from both parental F. hepatica and F. gigantica. The hybrids inherited phenotypic characteristics such as ratio of body length and width and infectivity to rats from parental Fasciola hepatica and F. gigantica. These findings suggest that reproductive isolation is incomplete between Fasciola hepatica and F. gigantica. Adults of the hybrids F1 and F2 were completely different in mode of reproduction from aspermic Fasciola forms that occur in Asia and seem to be offspring originated from hybridization between F. hepatica and F. gigantica and to reproduce parthenogenetically.

  3. Rotating-Sleeve Triboelectric-Electromagnetic Hybrid Nanogenerator for High Efficiency of Harvesting Mechanical Energy.

    Science.gov (United States)

    Cao, Ran; Zhou, Tao; Wang, Bin; Yin, Yingying; Yuan, Zuqing; Li, Congju; Wang, Zhong Lin

    2017-08-22

    Currently, a triboelectric nanogenerator (TENG) and an electromagnetic generator (EMG) have been hybridized to effectively scavenge mechanical energy. However, one critical issue of the hybrid device is the limited output power due to the mismatched output impedance between the two generators. In this work, impedance matching between the TENG and EMG is achieved facilely through commercial transformers, and we put forward a highly integrated hybrid device. The rotating-sleeve triboelectric-electromagnetic hybrid nanogenerator (RSHG) is designed by simulating the structure of a common EMG, which ensures a high efficiency in transferring ambient mechanical energy into electric power. The RSHG presents an excellent performance with a short-circuit current of 1 mA and open-circuit voltage of 48 V at a rotation speed of 250 rpm. Systematic measurements demonstrate that the hybrid nanogenerator can deliver the largest output power of 13 mW at a loading resistance of 8 kΩ. Moreover, it is demonstrated that a wind-driven RSHG can light dozens of light-emitting diodes and power an electric watch. The distinctive structure and high output performance promise the practical application of this rotating-sleeve structured hybrid nanogenerator for large-scale energy conversion.

  4. Optical and mechanical tolerances in hybrid concentrated thermal-PV solar trough.

    Science.gov (United States)

    Diaz, Liliana Ruiz; Cocilovo, Byron; Miles, Alexander; Pan, Wei; Blanche, Pierre-Alexandre; Norwood, Robert A

    2018-05-14

    Hybrid thermal-PV solar trough collectors combine concentrated photovoltaics and concentrated solar power technology to harvest and store solar energy. In this work, the optical and mechanical requirements for optimal efficiency are analyzed using non-sequential ray tracing techniques. The results are used to generate opto-mechanical tolerances that can be compared to those of traditional solar collectors. We also explore ideas on how to relieve tracking tolerances for single-axis solar collectors. The objective is to establish a basis for tolerances required for the fabrication and manufacturing of hybrid solar trough collectors.

  5. Effect of natural fibers and bio-resins on mechanical properties in hybrid and non-hybrid composites

    Science.gov (United States)

    Fragassa, Cristiano

    2016-05-01

    The aim of the present experimental investigation was to perform a comparative analysis concerning the influence on mechanical properties of natural fibers and/or bio-resins in reinforced thermoset composites. Flax and basalt fibers were selected as natural reinforcements, as single constituents or in hybrid combination. Glass synthetic fibers were used for comparison. Eco-friendly matrixes, both epoxy or vinylester, were considered and compared with composites based on traditional resins. Samples were fabricated by hand lay-up and resin infusion techniques. Cures were accelerated and controlled by applying heat and pressure in autoclave. Tensile, flexural and impact tests were carried out according to ASTM standards.

  6. Vibrotactile using micromachined electromagnetic actuators array

    International Nuclear Information System (INIS)

    Talbi, A; Ducloux, O; Tiercelin, N; Deblock, Y; Pernod, P; Preobrazhensky, V

    2006-01-01

    One motivating application of this technology is the development of a tactile display interface, where discrete mechanical actuators apply vibratory excitation at discrete locations on the skin. Specifically, this paper describes the development fabrication and characterization of a 4 x 4 micro-actuator array of vibrating pixels for fingertip tactile communication. The vibrting pixels are generated by using an electromagnetic microresonator. The fabrication sequence and the actuation performance of the array are also presented

  7. Dynamic behavior of the mechanical systems from the structure of a hybrid automobile

    Science.gov (United States)

    Dinel, Popa; Irina, Tudor; Nicolae-Doru, Stănescu

    2017-10-01

    In introduction are presented solutions of planetary mechanisms that can be used in the construction of the hybrid automobiles where the thermal and electrical sources must be coupled. The systems have in their composition a planetary mechanism with two degrees of mobility at which are coupled a thermal engine, two revertible electrical machines, a gear transmission with four gears and a differential mechanism which transmits the motion at the driving wheels. For the study of the dynamical behavior, with numerical results, one designs such mechanisms, models the elements with solids in AutoCAD, and obtains the mechanical properties of the elements. Further on, we present and solve the equations of motion of a hybrid automotive for which one knows the dynamical parameters.

  8. High Performance Flexible Actuator of Urchin-Like ZnO Nanostructure/Polyvinylenefluoride Hybrid Thin Film with Graphene Electrodes for Acoustic Generator and Analyzer.

    Science.gov (United States)

    Cheong, Oug Jae; Lee, James S; Kim, Jae Hyun; Jang, Jyongsik

    2016-05-01

    A bass frequency response enhanced flexible polyvinylidene fluoride (PVDF) based thin film acoustic actuator is successfully fabricated. High concentrations of various zinc oxide (ZnO) is embedded in PVDF matrix, enhancing the β phase content and the dielectric property of the composite thin film. ZnO acts as a nucleation agent for the crystallization of PVDF. A chemical vapor deposition grown graphene is used as electrodes, enabling high electron mobility for the distortion free acoustic signals. The frequency response of the fabricated acoustic actuator is studied as a function of the film thickness and filler content. The optimized film has a thickness of 80 μm with 30 wt% filler content and shows 72% and 42% frequency response enhancement in bass and midrange compared to the commercial PVDF, respectively. Also, the total harmonic distortion decreases to 82% and 74% in the bass and midrange regions, respectively. Furthermore, the composite film shows a promising potential for microphone applications. Most of all, it is demonstrated that acoustic actuator performance is strongly influenced by degree of PVDF crystalline. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Magnetically actuated mechanical stimuli on Fe3O4/mineralized collagen coatings to enhance osteogenic differentiation of the MC3T3-E1 cells.

    Science.gov (United States)

    Zhuang, Junjun; Lin, Suya; Dong, Lingqing; Cheng, Kui; Weng, Wenjian

    2018-04-15

    Mechanical stimuli at the bone-implant interface are considered to activate the mechanotransduction pathway of the cell to improve the initial osseointegration establishment and to guarantee clinical success of the implant. However, control of the mechanical stimuli at the bone-implant interface still remains a challenge. In this study, we have designed a strategy of a magnetically responsive coating on which the mechanical stimuli is controlled because of coating deformation under static magnetic field (SMF). The iron oxide nanoparticle/mineralized collagen (IOP-MC) coatings were electrochemically codeposited on titanium substrates in different quantities of IOPs and distributions; the resulting coatings were verified to possess swelling behavior with flexibility same as that of hydrogel. The relative quantity of IOP to collagen and the IOP distribution in the coatings were demonstrated to play a critical role in mediating cell behavior. The cells present on the outer layer of the distributed IOP-MC (O-IOP-MC) coating with a mass ratio of 0.67 revealed the most distinct osteogenic differentiation activity being promoted, which could be attributed to the maximized mechanical stimuli with exposure to SMF. Furthermore, the enhanced osteogenic differentiation of the stimulated MC3T3-E1 cells originated from magnetically actuated mechanotransduction signaling pathway, embodying the upregulated expression of osteogenic-related and mechanotransduction-related genes. This work therefore provides a promising strategy for implementing mechanical stimuli to activate mechanotransduction on the bone-implant interface and thus to promote osseointegration. The magnetically actuated coating is designed to produce mechanical stimuli to cells for promoting osteogenic differentiation based on the coating deformation. Iron oxide nanoparticles (IOPs) were incorporated into the mineralized collagen coatings (MC) forming the composite coatings (IOP-MC) with spatially distributed IOPs

  10. Recent Progress on Cellulose-Based Electro-Active Paper, Its Hybrid Nanocomposites and Applications

    OpenAIRE

    Asif Khan; Zafar Abas; Heung Soo Kim; Jaehwan Kim

    2016-01-01

    We report on the recent progress and development of research into cellulose-based electro-active paper for bending actuators, bioelectronics devices, and electromechanical transducers. The cellulose electro-active paper is characterized in terms of its biodegradability, chirality, ample chemically modifying capacity, light weight, actuation capability, and ability to form hybrid nanocomposites. The mechanical, electrical, and chemical characterizations of the cellulose-based electro-active pa...

  11. Studying the Mechanism of Hybrid Nanoparticle Photoresists: Effect of Particle Size on Photopatterning

    KAUST Repository

    Li, Li

    2015-07-28

    © 2015 American Chemical Society. Hf-based hybrid photoresist materials with three different organic ligands were prepared by a sol-gel-based method, and their patterning mechanism was investigated in detail. All hybrid nanoparticle resists are patternable using UV exposure. Their particle sizes show a dramatic increase from the initial 3-4 nm to submicron size after exposure, with no apparent inorganic content or thermal property change detected. XPS results showed that the mass percentage of the carboxylic group in the structure of nanoparticles decreased with increasing exposure duration. The particle coarsening sensitivities of those hybrid nanoparticles are consistent with their EUV performance. The current work provides an understanding for the development mechanism and future guidance for the design and processing of high performance resist materials for large-scale microelectronics device fabrication.

  12. The mechanical design of hybrid graphene/boron nitride nanotransistors: Geometry and interface effects

    Science.gov (United States)

    Einalipour Eshkalak, Kasra; Sadeghzadeh, Sadegh; Jalaly, Maisam

    2018-02-01

    From electronic point of view, graphene resembles a metal or semi-metal and boron nitride is a dielectric material (band gap = 5.9 eV). Hybridization of these two materials opens band gap of the graphene which has expansive applications in field-effect graphene transistors. In this paper, the effect of the interface structure on the mechanical properties of a hybrid graphene/boron nitride was studied. Young's modulus, fracture strain and tensile strength of the models were simulated. Three likely types (hexagonal, octagonal and decagonal) were found for the interface of hybrid sheet after relaxation. Although Csbnd B bonds at the interface were indicated to result in more promising electrical properties, nitrogen atoms are better choice for bonding to carbon for mechanical applications.

  13. Experimental Investigation on Mechanical Properties of Hemp/E-Glass Fabric Reinforced Polyester Hybrid Composites

    Directory of Open Access Journals (Sweden)

    M R SANJAY

    2016-09-01

    Full Text Available This research work has been focusing on Hemp fibers has an alternative reinforcement for fiber reinforced polymer composites due to its eco-friendly and biodegradable characteristics. This work has been carried out to evaluate the mechanical properties of hemp/E-glass fabrics reinforced polyester hybrid composites. Vacuum bagging method was used for the preparation of six different kinds of hemp/glass fabrics reinforced polyester composite laminates as per layering sequences. The tensile, flexural, impact and water absorption tests of these hybrid composites were carried out experimentally according to ASTM standards. It reveals that an addition of E-glass fabrics with hemp fabrics can increase the mechanical properties of composites and decrease the water absorption of the hybrid composites.

  14. Hybrid magnetic mechanism for active locomotion based on inchworm motion

    International Nuclear Information System (INIS)

    Kim, Sung Hoon; Hashi, Shuichiro; Ishiyama, Kazushi

    2013-01-01

    Magnetic robots have been studied in the past. Insect-type micro-robots are used in various biomedical applications; researchers have developed inchworm micro-robots for endoscopic use. A biological inchworm has a looping locomotion gait. However, most inchworm micro-robots depend on a general bending, or bellows, motion. In this paper, we introduce a new robotic mechanism using magnetic force and torque control in a rotating magnetic field for a looping gait. The proposed robot is controlled by the magnetic torque, attractive force, and body mechanisms (two stoppers, flexible body, and different frictional legs). The magnetic torque generates a general bending motion. In addition, the attractive force and body mechanisms produce the robot’s looping motion within a rotating magnetic field and without the use of an algorithm for field control. We verified the device’s performance and analyzed the motion through simulations and various experiments. The robot mechanism can be applied to active locomotion for various medical robots, such as wireless endoscopes. (technical note)

  15. Soft Pneumatic Actuators for Rehabilitation

    Directory of Open Access Journals (Sweden)

    Guido Belforte

    2014-05-01

    Full Text Available Pneumatic artificial muscles are pneumatic devices with practical and various applications as common actuators. They, as human muscles, work in agonistic-antagonistic way, giving a traction force only when supplied by compressed air. The state of the art of soft pneumatic actuators is here analyzed: different models of pneumatic muscles are considered and evolution lines are presented. Then, the use of Pneumatic Muscles (PAM in rehabilitation apparatus is described and the general characteristics required in different applications are considered, analyzing the use of proper soft actuators with various technical properties. Therefore, research activity carried out in the Department of Mechanical and Aerospace Engineering in the field of soft and textile actuators is presented here. In particular, pneumatic textile muscles useful for active suits design are described. These components are made of a tubular structure, with an inner layer of latex coated with a deformable outer fabric sewn along the edge. In order to increase pneumatic muscles forces and contractions Braided Pneumatic Muscles are studied. In this paper, new prototypes are presented, based on a fabric construction and various kinds of geometry. Pressure-force-deformation tests results are carried out and analyzed. These actuators are useful for rehabilitation applications. In order to reproduce the whole upper limb movements, new kind of soft actuators are studied, based on the same principle of planar membranes deformation. As an example, the bellows muscle model and worm muscle model are developed and described. In both cases, wide deformations are expected. Another issue for soft actuators is the pressure therapy. Some textile sleeve prototypes developed for massage therapy on patients suffering of lymph edema are analyzed. Different types of fabric and assembly techniques have been tested. In general, these Pressure Soft Actuators are useful for upper/lower limbs treatments

  16. On a mechanism of switching off low-hybrid run away currents in tokamak devices

    International Nuclear Information System (INIS)

    Budnikov, V.N.; Esipov, L.A.; Irzak, M.A.

    1990-01-01

    The problem of the generation of low-hybrid run-away currents (LR) in tokamak devices is described. The mechanism of switching off LRCs is considered. Qualitative representation of the density limit, the transitions of which stops the generation of currents, is given

  17. Evaluation of mechanical properties of hybrid fiber (hemp, jute, kevlar) reinforced composites

    Science.gov (United States)

    Suresha, K. V.; Shivanand, H. K.; Amith, A.; Vidyasagar, H. N.

    2018-04-01

    In today's world composites play wide role in all the engineering fields. The reinforcement of composites decides the properties of the material. Natural fiber composites compared to synthetic fiber possesses poor mechanical properties. The solution for this problem is to use combination of natural fiber and synthetic fiber. Hybridization helps to improve the overall mechanical properties of the material. In this study, hybrid reinforced composites of Hemp fabric/Kevlar fabric/Epoxy and Jute fabric/ Kevlar fabric/Epoxy composites are fabricated using Simple hand layup technique followed by Vacuum bagging process. Appropriate test methods as per standards and guidelines are followed to analyze mechanical behavior of the composites. The mechanical characteristics like tensile, compression and flexural properties of the hybrid reinforced composites are tested as per the ASTM standards by series of tensile test; compression test and three point bending tests were conducted on the hybrid composites. A quantitative relationship between the Hemp fabric/Kevlar fabric/Epoxy and Jute/ Kevlar fabric/Epoxy has been established with constant thickness.

  18. Flight control actuation system

    Science.gov (United States)

    Wingett, Paul T. (Inventor); Gaines, Louie T. (Inventor); Evans, Paul S. (Inventor); Kern, James I. (Inventor)

    2006-01-01

    A flight control actuation system comprises a controller, electromechanical actuator and a pneumatic actuator. During normal operation, only the electromechanical actuator is needed to operate a flight control surface. When the electromechanical actuator load level exceeds 40 amps positive, the controller activates the pneumatic actuator to offset electromechanical actuator loads to assist the manipulation of flight control surfaces. The assistance from the pneumatic load assist actuator enables the use of an electromechanical actuator that is smaller in size and mass, requires less power, needs less cooling processes, achieves high output forces and adapts to electrical current variations. The flight control actuation system is adapted for aircraft, spacecraft, missiles, and other flight vehicles, especially flight vehicles that are large in size and travel at high velocities.

  19. Mechanical Properties, Cytocompatibility and Manufacturability of Chitosan:PEGDA Hybrid-Gel Scaffolds by Stereolithography.

    Science.gov (United States)

    Morris, Viola B; Nimbalkar, Siddharth; Younesi, Mousa; McClellan, Phillip; Akkus, Ozan

    2017-01-01

    Extracellular matrix mimetic hydrogels which hybridize synthetic and natural polymers offer molecularly-tailored, bioactive properties and tunable mechanical strength. In addition, 3D bioprinting by stereolithography allows fabrication of internal pores and defined macroscopic shapes. In this study, we formulated a hybrid biocompatible resin using natural and synthetic polymers (chitosan and polyethylene glycol diacrylate (PEGDA), respectively) by controlling molecular weight of chitosan, feed-ratios, and photo-initiator concentration. Ear-shaped, hybrid scaffolds were fabricated by a stereolithographic method using a 405 nm laser. Hybrid hydrogel scaffolds of chitosan (50-190 kDa) and PEGDA (575 Da) were mixed at varying feed-ratios. Some of the cationic, amino groups of chitosan were neutralized by dialysis in acidic solution containing chitosan in excess of sodium acetate solution to inhibit quenching of newly formed photoradicals. A feed-ratio of 1:7.5 was found to be the most appropriate of the formulations considered in this study in terms of mechanical properties, cell adhesion, and printability. The biofabricated hybrid scaffold showed interconnected, homogeneous pores with a nominal pore size of 50 µm and an elastic modulus of ~400 kPa. Moreover, long-term cell viability and cell spreading was observed via actin filament staining. Printability of the biocompatible resin was confirmed by printing thresholded MR images of an ear and the feed ratio of 1:7.5 provided the most faithful reproduction of the shape. To the best of our knowledge, this is the first report of stereolithographic printing hybridizing cell-adhesive properties of chitosan with mechanical robustness of PEG in scaffolds suitable for repair of complex tissue geometries, such as those of the human ear.

  20. Hybrid Systems: Cold Atoms Coupled to Micro Mechanical Oscillators =

    Science.gov (United States)

    Montoya Monge, Cris A.

    Micro mechanical oscillators can serve as probes in precision measurements, as transducers to mediate photon-phonon interactions, and when functionalized with magnetic material, as tools to manipulate spins in quantum systems. This dissertation includes two projects where the interactions between cold atoms and mechanical oscillators are studied. In one of the experiments, we have manipulated the Zeeman state of magnetically trapped Rubidium atoms with a magnetic micro cantilever. The results show a spatially localized effect produced by the cantilever that agrees with Landau-Zener theory. In the future, such a scalable system with highly localized interactions and the potential for single-spin sensitivity could be useful for applications in quantum information science or quantum simulation. In a second experiment, work is in progress to couple a sample of optically trapped Rubidium atoms to a levitated nanosphere via an optical lattice. This coupling enables the cooling of the center-of-mass motion of the nanosphere by laser cooling the atoms. In this system, the atoms are trapped in the optical lattice while the sphere is levitated in a separate vacuum chamber by a single-beam optical tweezer. Theoretical analysis of such a system has determined that cooling the center-of-mass motion of the sphere to its quantum ground state is possible, even when starting at room temperature, due to the excellent environmental decoupling achievable in this setup. Nanospheres cooled to the quantum regime can provide new tests of quantum behavior at mesoscopic scales and have novel applications in precision sensing.

  1. Compact hybrid cell based on a convoluted nanowire structure for harvesting solar and mechanical energy

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Chen; Wang, Zhong Lin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2011-02-15

    A fully integrated, solid-state, compact hybrid cell (CHC) that comprises ''convoluted'' ZnO nanowire structures for concurrent harvesting of both solar and mechanical energy is demonstrated. The compact hybrid cell is based on a conjunction design of an organic solid-state dye-sensitized solar cell (DSSC) and piezoelectric nanogenerator in one compact structure. The CHC shows a significant increase in output power, clearly demonstrating its potential for simultaneously harvesting multiple types of energy for powering small electronic devices for independent, sustainable, and mobile operation. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Buckling Pneumatic Linear Actuators Inspired by Muscle

    OpenAIRE

    Yang, Dian; Verma, Mohit Singh; So, Ju-Hee; Mosadegh, Bobak; Keplinger, Christoph; Lee, Benjamin; Khashai, Fatemeh; Lossner, Elton Garret; Suo, Zhigang; Whitesides, George McClelland

    2016-01-01

    The mechanical features of biological muscles are difficult to reproduce completely in synthetic systems. A new class of soft pneumatic structures (vacuum-actuated muscle-inspired pneumatic structures) is described that combines actuation by negative pressure (vacuum), with cooperative buckling of beams fabricated in a slab of elastomer, to achieve motion and demonstrate many features that are similar to that of mammalian muscle.

  3. Conducting Polymer Actuators: Prospects and Limitations

    DEFF Research Database (Denmark)

    Skaarup, Steen

    Actuators constructed with a conjugated polymer as the active part have been predicted to have a number of highly desirable properties: Large mechanical strength, high power density, i.e. high actuation speeds possible, sufficient maximum strain values, high reversibility and safe, low voltages (...

  4. Conjugated Polymer Actuators: Prospects and Limitations

    DEFF Research Database (Denmark)

    Skaarup, Steen

    2007-01-01

    Actuators constructed with a conjugated polymer as the active part have been predicted to have a number of highly desirable properties: Large mechanical strength, high power density, i.e. high actuation speeds possible, sufficient maximum strain values, high reversibility and safe, low voltages (1...

  5. Sex ratio meiotic drive as a plausible evolutionary mechanism for hybrid male sterility.

    Directory of Open Access Journals (Sweden)

    Linbin Zhang

    2015-03-01

    Full Text Available Biological diversity on Earth depends on the multiplication of species or speciation, which is the evolution of reproductive isolation such as hybrid sterility between two new species. An unsolved puzzle is the exact mechanism(s that causes two genomes to diverge from their common ancestor so that some divergent genes no longer function properly in the hybrids. Here we report genetic analyses of divergent genes controlling male fertility and sex ratio in two very young fruitfly species, Drosophila albomicans and D. nasuta. A majority of the genetic divergence for both traits is mapped to the same regions by quantitative trait loci mappings. With introgressions, six major loci are found to contribute to both traits. This genetic colocalization implicates that genes for hybrid male sterility have evolved primarily for controlling sex ratio. We propose that genetic conflicts over sex ratio may operate as a perpetual dynamo for genome divergence. This particular evolutionary mechanism may largely contribute to the rapid evolution of hybrid male sterility and the disproportionate enrichment of its underlying genes on the X chromosome--two patterns widely observed across animals.

  6. Sex ratio meiotic drive as a plausible evolutionary mechanism for hybrid male sterility.

    Science.gov (United States)

    Zhang, Linbin; Sun, Tianai; Woldesellassie, Fitsum; Xiao, Hailian; Tao, Yun

    2015-03-01

    Biological diversity on Earth depends on the multiplication of species or speciation, which is the evolution of reproductive isolation such as hybrid sterility between two new species. An unsolved puzzle is the exact mechanism(s) that causes two genomes to diverge from their common ancestor so that some divergent genes no longer function properly in the hybrids. Here we report genetic analyses of divergent genes controlling male fertility and sex ratio in two very young fruitfly species, Drosophila albomicans and D. nasuta. A majority of the genetic divergence for both traits is mapped to the same regions by quantitative trait loci mappings. With introgressions, six major loci are found to contribute to both traits. This genetic colocalization implicates that genes for hybrid male sterility have evolved primarily for controlling sex ratio. We propose that genetic conflicts over sex ratio may operate as a perpetual dynamo for genome divergence. This particular evolutionary mechanism may largely contribute to the rapid evolution of hybrid male sterility and the disproportionate enrichment of its underlying genes on the X chromosome--two patterns widely observed across animals.

  7. Lightweight mechanical amplifiers for rolled dielectric elastomer actuators and their integration with bio-inspired wing flappers

    International Nuclear Information System (INIS)

    Lau, Gih-Keong; Lim, Hoong-Ta; Teo, Jing-Ying; Chin, Yao-Wei

    2014-01-01

    Dielectric elastomer actuators (DEAs) are attractive for use in bio-inspired flapping-wing robots because they have high work density (specific energy) and can produce a large actuation strain. Although the active membrane of a dielectric elastomer is lightweight, the support structure that pre-tensions the elastomeric membrane is massive and it lowers the overall work density. If the DEA is to be used successfully to drive flapping-wing robots, its support structure must be as lightweight as possible. In this work, we designed, analysed, and developed a lightweight shell using a cross-ply laminate of carbon fibre reinforced polymer (CFRP) to pre-strain a rolled DEA. The CFRP shell was shown to weigh 24.3% of the total mass for the whole DEA assembly, while providing up to 35.0% axial pre-strain to a rolled DEA (BJB-5005 silicone rubber). This DEA assembly using the CFRP shell achieved 30.9% of the theoretical work density for a BJB-TC5005 membrane at 33.5 MV m −1 . In comparison, spring rolls with a massive spring core were reported with overall work density merely 10–20% of the maximum value. Furthermore, this CFRP shell can amplify an axial DEA stroke into a larger transverse shell deformation. With these deformation characteristics, this CFRP shell and a rolled DEA were successfully integrated with an insect-inspired thoracic mechanism and they were shown to be feasible to drive it for a flapping wing. (paper)

  8. The Mechanical Properties of Candidate Superalloys for a Hybrid Turbine Disk

    Science.gov (United States)

    Gabb, Timothy P.; MacKay, Rebecca A.; Draper, Susan L.; Sudbrack, Chantal K.; Nathal, Michael V.

    2013-01-01

    The mechanical properties of several cast blade superalloys and one powder metallurgy disk superalloy were assessed for potential use in a dual alloy hybrid disk concept of joined dissimilar bore and web materials. Grain size was varied for each superalloy class. Tensile, creep, fatigue, and notch fatigue tests were performed at 704 to 815 degC. Typical microstructures and failure modes were determined. Preferred materials were then selected for future study as the bore and rim alloys in this hybrid disk concept. Powder metallurgy superalloy LSHR at 15 micron grain size and single crystal superalloy LDS-1101+Hf were selected for further study, and future work is recommended to develop the hybrid disk concept.

  9. Boron nitride-MWCNT/epoxy hybrid nanocomposites: Preparation and mechanical properties

    International Nuclear Information System (INIS)

    Ulus, Hasan; Üstün, Tugay; Eskizeybek, Volkan; Şahin, Ömer Sinan; Avcı, Ahmet; Ekrem, Mürsel

    2014-01-01

    Highlights: • We studied the effects of BN nanoplatelets on tensile strength and elasticity modulus for polymer composites. • We investigated the synergetic effects of BN nanoplatelets and MWCNTs on tensile strength and elasticity modulus for polymer composites. • Fracture surfaces were examined by SEM analysis. - Abstract: In this study, production and mechanical properties of hybrid nanocomposites have been investigated. Hybrid nanocomposites are consisting of boron nitride nanoplatelets (BN) and multiwall carbon nanotubes (MWCNT) embedded in epoxy resin. The BN and MWCNT were mixed to epoxy resin in different weight fractions and mixtures were utilized for tensile test specimen production. The synthesized BN and produced hybrid nanocomposites were characterized by SEM, TEM, XRD, FT-IR and TGA analyses. The elasticity modulus and tensile strength values were obtained via tensile tests. The fracture morphologies were investigated after tensile test by means of scanning electron microscopy

  10. Adsorption mechanism of magnetically separable Fe{sub 3}O{sub 4}/graphene oxide hybrids

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang, Ke [Department of Chemical and Environment Engineering, Wuyi University, Jiangmen, Guangdong 529020 (China); Zhu, Chuanhe [Department of Civil, Construction and Environmental Engineering, Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011 (United States); Zhao, Ya; Wang, Leichao [Department of Chemical and Environment Engineering, Wuyi University, Jiangmen, Guangdong 529020 (China); Xie, Shan, E-mail: wyuchemxs@126.com [Department of Chemical and Environment Engineering, Wuyi University, Jiangmen, Guangdong 529020 (China); Wang, Qun, E-mail: qunwang@iastate.edu [Department of Civil, Construction and Environmental Engineering, Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011 (United States)

    2015-11-15

    Graphical abstract: A recyclable Fe{sub 3}O{sub 4}/graphene oxide (GO) magnetic hybrid was successfully synthesized via a facile one-pot polylol approach and exhibited an effective adsorption of BPA in aqueous solution. - Highlights: • Magnetically separable Fe{sub 3}O{sub 4}/GO hybrids were synthesized via a facile one-pot polylol approach. • The Fe{sub 3}O{sub 4}/GO hybrid could be easily recovered and met the need of magnetic separation, exhibiting excellent reproducibility and reusability. • The hybrids showed excellent adsorption ability for bisphenol A in aqueous solution. • The effect of pH value, temperature and coexisting ions on the adsorption was studied. • π–π interactions were postulated to be the primary mechanisms of adsorption of BPA on Fe{sub 3}O{sub 4}/GO hybrids. - Abstract: A reclaimable Fe{sub 3}O{sub 4}/graphene oxide (GO) magnetic hybrid was successfully synthesized via a facile one-pot polyol approach and employed as a recyclable adsorbent for Bisphenol A (BPA) in aqueous solutions. The maximum adsorption capacity (q{sub m}) of the Fe{sub 3}O{sub 4}/GO hybrid for BPA was 72.80 mg/g at 273 K. The kinetics of the adsorption process and the adsorption isotherm data were fitted using the Freundlich equation and a pseudo-second-order kinetic model. The results of the thermodynamic parameters ΔH°, ΔS° and ΔG° showed that the adsorption process was exothermic and spontaneous. Furthermore, the reusability of the samples was investigated, and the results indicated that the samples exhibited high stability. The magnetic characterization demonstrated that hybrids were superparamagnetic and could be recovered conveniently by magnetic separation. The strong π–π interaction was determined to be the predominant driving force behind the adsorption of BPA onto the Fe{sub 3}O{sub 4}/GO hybrid. Therefore, the Fe{sub 3}O{sub 4}/GO hybrid could be regarded as a potential adsorbent for wastewater treatment and purification processes.

  11. Stepper Motor Actuated Microvalve

    Energy Technology Data Exchange (ETDEWEB)

    Fazal, Imran; Louwerse, Marcus; Jansen, Henri; Elwenspoek, Miko [MESA Research Institute, University of Twente EWI/TST, P. off Box 217 Enschede (Netherlands)

    2006-04-01

    We present the design, fabrication and characterization of a novel microvalve realized by combining micro and fine machining techniques. The design is for high flow rates at high pressure difference between inlet and outlet, burst pressure of up to 15 bars, there is no power consumption required for the valve to maintain its position during operation in any intermediate state and the process gas does not interact with the actuation mechanism. The microvalve was experimentally characterized with airflows. It is shown that flow rates of 220 ml/min at a pressure difference of 4 bars could be achieved with the minimum accurate flow rate of 2-8 ml/min.

  12. Assessment of Excess Sludge Ultrasonic, Mechanical and Hybrid Pretreatment in Relation to the Energy Parameters

    Directory of Open Access Journals (Sweden)

    Łukasz Skórkowski

    2018-04-01

    Full Text Available Anaerobic digestion is the most common stabilization process at large sewage treatment plants. To improve its effects, a sludge pre-conditioning process called disintegration is recommended. The aim of the presented study was to compare the direct effects of various types of mechanical disintegration, performed for the same excess sludge, in relation to the energy parameters and effectiveness of the process. Four different disintegration methods were used: mechanical disintegration in semi-technical and laboratory scale homogenizing mixers, ultrasonic disintegration (US and combined (hybrid process. The disintegration was performed for volumetric energy EV = 4.67–100 kWh m−3, the results were evaluated based on dispersion (kdCOD, kdCST, lysis (kdSCOD, acidification (kdVFA and nutrient release (kdTN, kdTP disintegration indicators. The statistical analysis of the results indicates the influence of disintegrator type (mixer/US/hybrid, scale (laboratory/semi-technical and energy input on the direct results of disintegration. Hybrid disintegration delivered better direct results than two pre-treatment processes used separately. The efficiency of the hybrid process defined as the increase of the indicator (disintegration products—∆FCOD, ∆SCOD per unit of energy was considerably higher than for a single stage disintegration process.

  13. Mechanical properties of hybrid kenaf/glass reinforced epoxy composite for passenger car bumper beam

    International Nuclear Information System (INIS)

    Davoodi, M.M.; Sapuan, S.M.; Ahmad, D.; Ali, Aidy; Khalina, A.; Jonoobi, Mehdi

    2010-01-01

    It is estimated that the annual world car production rate will reach 76 million vehicles per year by 2020. New regulations such as the EU End of Life Vehicles (ELV) regulations are forcing car manufacturers to consider the environmental impact of their production and possibly shift from the use of synthetic materials to the use of agro-based materials. Poor mechanical properties and certain manufacturing limitations currently limit the use of agro-based materials to non-structural and semi-structural automotive components. The hybridization of natural fiber with glass fiber provides a method to improve the mechanical properties over natural fibers alone. This research is focused on a hybrid of kenaf/glass fiber to enhance the desired mechanical properties for car bumper beams as automotive structural components with modified sheet molding compound (SMC). A specimen without any modifier is tested and compared with a typical bumper beam material called glass mat thermoplastic (GMT). The results indicate that some mechanical properties such as tensile strength, Young's modulus, flexural strength and flexural modulus are similar to GMT, but impact strength is still low, and shows the potential for utilization of hybrid natural fiber in some car structural components such as bumper beams.

  14. Shape-Memory-Alloy Actuator For Flight Controls

    Science.gov (United States)

    Barret, Chris

    1995-01-01

    Report proposes use of shape-memory-alloy actuators, instead of hydraulic actuators, for aerodynamic flight-control surfaces. Actuator made of shape-memory alloy converts thermal energy into mechanical work by changing shape as it makes transitions between martensitic and austenitic crystalline phase states of alloy. Because both hot exhaust gases and cryogenic propellant liquids available aboard launch rockets, shape-memory-alloy actuators exceptionally suited for use aboard such rockets.

  15. Bi-directional series-parallel elastic actuator and overlap of the actuation layers.

    Science.gov (United States)

    Furnémont, Raphaël; Mathijssen, Glenn; Verstraten, Tom; Lefeber, Dirk; Vanderborght, Bram

    2016-01-27

    Several robotics applications require high torque-to-weight ratio and energy efficient actuators. Progress in that direction was made by introducing compliant elements into the actuation. A large variety of actuators were developed such as series elastic actuators (SEAs), variable stiffness actuators and parallel elastic actuators (PEAs). SEAs can reduce the peak power while PEAs can reduce the torque requirement on the motor. Nonetheless, these actuators still cannot meet performances close to humans. To combine both advantages, the series parallel elastic actuator (SPEA) was developed. The principle is inspired from biological muscles. Muscles are composed of motor units, placed in parallel, which are variably recruited as the required effort increases. This biological principle is exploited in the SPEA, where springs (layers), placed in parallel, can be recruited one by one. This recruitment is performed by an intermittent mechanism. This paper presents the development of a SPEA using the MACCEPA principle with a self-closing mechanism. This actuator can deliver a bi-directional output torque, variable stiffness and reduced friction. The load on the motor can also be reduced, leading to a lower power consumption. The variable recruitment of the parallel springs can also be tuned in order to further decrease the consumption of the actuator for a given task. First, an explanation of the concept and a brief description of the prior work done will be given. Next, the design and the model of one of the layers will be presented. The working principle of the full actuator will then be given. At the end of this paper, experiments showing the electric consumption of the actuator will display the advantage of the SPEA over an equivalent stiff actuator.

  16. Study on Two-segment Electric-mechanical Composite Braking Strategy of Tracked Vehicle Hybrid Transmission System

    OpenAIRE

    Ma, Tian; Gai, Jiangtao; Ma, Xiaofeng

    2010-01-01

    In order to lighten abrasion of braking system of hybrid electric tracked vehicle, according to characteristic of hybrid electric transmission, electric-mechanical composite braking method was proposed. By means of analyzing performance of electric braking and mechanical braking and three-segment composite braking strategy, two-segment electric-mechanical composite braking strategy was put forward in this paper. Simulation results of Matlab/Simulink indicated that the two-segment electric-mec...

  17. Synthesis and mechanical behavior of carbon nanotube-magnesium composites hybridized with nanoparticles of alumina

    International Nuclear Information System (INIS)

    Thakur, Sanjay Kumar; Srivatsan, T.S.; Gupta, Manoj

    2007-01-01

    Carbon nanotubes reinforced magnesium based composites were prepared with diligence and care using the powder metallurgy route coupled with rapid microwave sintering. Nanometer-sized particles of alumina were used to hybridize the carbon nanotubes reinforcement in the magnesium matrix so as to establish the intrinsic influence of hybridization on mechanical behavior of the resultant composite material. The yield strength, tensile strength and strain-to-failure of the carbon nanotubes-magnesium composites were found to increase with the addition of nanometer-sized alumina particles to the composite matrix. Scanning electron microscopy observations of the fracture surfaces of the samples deformed and failed in uniaxial tension revealed the presence of cleavage-like features on the fracture surface indicative of the occurrence of locally brittle fracture mechanism in the composite microstructure

  18. Mechanism of single-frequency operation of the hybrid-CO2 laser

    International Nuclear Information System (INIS)

    Gondhalekar, A.; Heckenberg, N.R.; Holzhauer, E.

    1975-01-01

    The mechanism of a new method of obtaining high-power single-frequency pulses from a TEA-CO 2 laser is discussed. Measurements of the shape and monochromaticity of pulses from the hybrid laser which has both a TEA and a low-pressure gain section inside one resonator are presented. The mechanism of single-frequency operation of the hybrid laser is discussed with reference to numerical solutions of simplified rate equations. The low-pressure section provides gain only over a narrow range of frequencies so that a mode lying in that band-width builds up faster than neighboring modes to give a single-frequency pulse resembling in overall shape the normal TEA laser pulse. If the system is already lasing when the TEA discharge begins, the single-mode radiation already present rapidly grows to give a single-frequency pulse lacking a gain-switched peak. (U.S.)

  19. Hybrid simulation research on formation mechanism of tungsten nanostructure induced by helium plasma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Atsushi M., E-mail: ito.atsushi@nifs.ac.jp [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Takayama, Arimichi; Oda, Yasuhiro [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Tamura, Tomoyuki; Kobayashi, Ryo; Hattori, Tatsunori; Ogata, Shuji [Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Ohno, Noriyasu; Kajita, Shin [Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Yajima, Miyuki [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Noiri, Yasuyuki [Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Yoshimoto, Yoshihide [University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Saito, Seiki [Kushiro National College of Technology, Kushiro, Hokkaido 084-0916 (Japan); Takamura, Shuichi [Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota 470-0392 (Japan); Murashima, Takahiro [Tohoku University, 6-3, Aramaki-Aza-Aoba, Aoba-Ward, Sendai 980-8578 (Japan); Miyamoto, Mitsutaka [Shimane University, Matsue, Shimane 690-8504 (Japan); Nakamura, Hiroaki [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-08-15

    The generation of tungsten fuzzy nanostructure by exposure to helium plasma is one of the important problems for the use of tungsten material as divertor plates in nuclear fusion reactors. In the present paper, the formation mechanisms of the helium bubble and the tungsten fuzzy nanostructure were investigated by using several simulation methods. We proposed the four-step process which is composed of penetration step, diffusion and agglomeration step, helium bubble growth step, and fuzzy nanostructure formation step. As the fourth step, the formation of the tungsten fuzzy nanostructure was successfully reproduced by newly developed hybrid simulation combining between molecular dynamics and Monte-Carlo method. The formation mechanism of tungsten fuzzy nanostructure observed by the hybrid simulation is that concavity and convexity of the surface are enhanced by the bursting of helium bubbles in the region around the concavity.

  20. Flexible hybrid energy cell for simultaneously harvesting thermal, mechanical, and solar energies.

    Science.gov (United States)

    Yang, Ya; Zhang, Hulin; Zhu, Guang; Lee, Sangmin; Lin, Zong-Hong; Wang, Zhong Lin

    2013-01-22

    We report the first flexible hybrid energy cell that is capable of simultaneously or individually harvesting thermal, mechanical, and solar energies to power some electronic devices. For having both the pyroelectric and piezoelectric properties, a polarized poly(vinylidene fluoride) (PVDF) film-based nanogenerator (NG) was used to harvest thermal and mechanical energies. Using aligned ZnO nanowire arrays grown on the flexible polyester (PET) substrate, a ZnO-poly(3-hexylthiophene) (P3HT) heterojunction solar cell was designed for harvesting solar energy. By integrating the NGs and the solar cells, a hybrid energy cell was fabricated to simultaneously harvest three different types of energies. With the use of a Li-ion battery as the energy storage, the harvested energy can drive four red light-emitting diodes (LEDs).

  1. Simple structured hybrid WOLEDs based on incomplete energy transfer mechanism: from blue exciplex to orange dopant

    Science.gov (United States)

    Zhang, Tianyou; Zhao, Bo; Chu, Bei; Li, Wenlian; Su, Zisheng; Yan, Xingwu; Liu, Chengyuan; Wu, Hairuo; Gao, Yuan; Jin, Fangming; Hou, Fuhua

    2015-05-01

    Exciplex is well known as a charge transfer state formed between electron-donating and electron-accepting molecules. However, exciplex based organic light emitting diodes (OLED) often performed low efficiencies relative to pure phosphorescent OLED and could hardly be used to construct white OLED (WOLED). In this work, a new mechanism is developed to realize efficient WOLED with extremely simple structure by redistributing the energy of triplet exciplex to both singlet exciplex and the orange dopant. The micro process of energy transfer could be directly examined by detailed photoluminescence decay measurement and time resolved photoluminescence analysis. This strategy overcomes the low reverse intersystem crossing efficiency of blue exciplex and complicated device structure of traditional WOLED, enables us to achieve efficient hybrid WOLEDs. Based on this mechanism, we have successfully constructed both exciplex-fluorescence and exciplex-phosphorescence hybrid WOLEDs with remarkable efficiencies.

  2. Adaptive kanban control mechanism for a single-stage hybrid system

    Science.gov (United States)

    Korugan, Aybek; Gupta, Surendra M.

    2002-02-01

    In this paper, we consider a hybrid manufacturing system with two discrete production lines. Here the output of either production line can satisfy the demand for the same type of product without any penalties. The interarrival times for demand occurrences and service completions are exponentially distributed i.i.d. variables. In order to control this type of manufacturing system we suggest a single stage pull type control mechanism with adaptive kanbans and state independent routing of the production information.

  3. Soft, Rotating Pneumatic Actuator.

    Science.gov (United States)

    Ainla, Alar; Verma, Mohit S; Yang, Dian; Whitesides, George M

    2017-09-01

    This article describes a soft pneumatic actuator that generates cyclical motion. The actuator consists of several (three, four, or five) chambers (arranged around the circumference of a circle surrounding a central rod) that can be actuated independently using negative pressure (or partial vacuum). Sequential actuation of the four-chamber device using reduced pressure moves the central rod cyclically in an approximately square path. We characterize the trajectory of the actuator and the force exerted by it, as we vary the material used for fabrication, the number of chambers, and the size of the actuator. We demonstrate two applications of this actuator: to deliver fluid while stirring (by replacing the central rod with a needle) and for locomotion that mimics a reptilian gait (by combining four actuators together).

  4. Actuators Using Piezoelectric Stacks and Displacement Enhancers

    Science.gov (United States)

    Bar-Cohen, Yoseph; Sherrit, Stewart; Bao, Xiaoqi; Badescu, Mircea; Lee, Hyeong Jae; Walkenmeyer, Phillip; Lih, Shyh-Shiuh

    2015-01-01

    Actuators are used to drive all active mechanisms including machines, robots, and manipulators to name a few. The actuators are responsible for moving, manipulating, displacing, pushing and executing any action that is needed by the mechanism. There are many types and principles of actuation that are responsible for these movements ranging from electromagnetic, electroactive, thermo-mechanic, piezoelectric, electrostrictive etc. Actuators are readily available from commercial producers but there is a great need for reducing their size, increasing their efficiency and reducing their weight. Studies at JPL’s Non Destructive Evaluation and Advanced Actuators (NDEAA) Laboratory have been focused on the use of piezoelectric stacks and novel designs taking advantage of piezoelectric’s potential to provide high torque/force density actuation and high electromechanical conversion efficiency. The actuators/motors that have been developed and reviewed in this paper are operated by various horn configurations as well as the use of pre-stress flexures that make them thermally stable and increases their coupling efficiency. The use of monolithic designs that pre-stress the piezoelectric stack eliminates the use of compression stress bolt. These designs enable the embedding of developed solid-state motors/actuators in any structure with the only macroscopically moving parts are the rotor or the linear translator. Finite element modeling and design tools were used to determine the requirements and operation parameters and the results were used to simulate, design and fabricate novel actuators/motors. The developed actuators and performance will be described and discussed in this paper.

  5. Analytical dynamic modeling of fast trilayer polypyrrole bending actuators

    International Nuclear Information System (INIS)

    Amiri Moghadam, Amir Ali; Moavenian, Majid; Tahani, Masoud; Torabi, Keivan

    2011-01-01

    Analytical modeling of conjugated polymer actuators with complicated electro-chemo-mechanical dynamics is an interesting area for research, due to the wide range of applications including biomimetic robots and biomedical devices. Although there have been extensive reports on modeling the electrochemical dynamics of polypyrrole (PPy) bending actuators, mechanical dynamics modeling of the actuators remains unexplored. PPy actuators can operate with low voltage while producing large displacement in comparison to robotic joints, they do not have friction or backlash, but they suffer from some disadvantages such as creep and hysteresis. In this paper, a complete analytical dynamic model for fast trilayer polypyrrole bending actuators has been proposed and named the analytical multi-domain dynamic actuator (AMDDA) model. First an electrical admittance model of the actuator will be obtained based on a distributed RC line; subsequently a proper mechanical dynamic model will be derived, based on Hamilton's principle. The purposed modeling approach will be validated based on recently published experimental results

  6. Hemicelluloses/montmorillonite hybrid films with improved mechanical and barrier properties

    Science.gov (United States)

    Chen, Ge-Gu; Qi, Xian-Ming; Li, Ming-Peng; Guan, Ying; Bian, Jing; Peng, Feng; Yao, Chun-Li; Sun, Run-Cang

    2015-11-01

    A facile and environmentally friendly method was introduced to incorporate montmorillonite (MMT) as an inorganic phase into quaternized hemicelluloses (QH) for forming hemicellulose-based films. Two fillers, polyvinyl alcohol (PVA) and chitin nanowhiskers (NCH), were added into the hemicelluloses/MMT hybrid matrices to prepare hybrid films, respectively. The hybrid films were nanocomposites with nacre-like structure and multifunctional characteristics including higher strength and good oxygen barrier properties via the electrostatic and hydrogen bonding interactions. The addition of PVA and NCH could induce changes in surface topography, and effectively enhance mechanical strength, thermal stability, transparency, and oxygen barrier properties. The tensile strengths of the composite films FPVA(0.3), FPVA(0.5), and FNCH(0.8) were 53.7, 46.3, and 50.1 MPa, respectively, which were 171%, 134%, and 153% larger than the FQH-MMT film (19.8 MPa). The tensile strength, and oxygen transmission rate of QH-MMT-PVA film were better than those of quaternized hemicelluloses/MMT films. Thus, the proper filler is very important for the strength of the hybrid film. These results provide insights into the understanding of the structural relationships of hemicellulose-based composite films in coating and packaging application for the future.

  7. Mechanical properties of steel/kenaf (hybrid) fibers added into concrete mixtures

    Science.gov (United States)

    Baarimah, A. O.; Syed Mohsin, S. M.

    2018-04-01

    This paper investigates the potential advantages of adding hybrid steel-kenaf fibers to concrete mixtures. Compression and flexural test were conducted on six concrete mixtures at 28 days to investigate the mechanical properties of the concrete. The experimental work consists of six concrete mixtures, in which the first mixture was a control mixture without adding any fiber. The following five concrete mixtures contain a total of 1% of volume fraction for steel, kenaf and a mixture of steel-kenaf (hybrid) fibers. Three ratios were considered for hybrid fibers with the ratios of 0.25/0.75, 0.5/0.5 and 0.75/0.25 for steel and kenaf fibers, respectively. From the investigation, it was observed that fibers have minimal effect on compressive strength of the concrete. However, the findings suggest promising improvement on the flexural strength of the concrete added with hybrid fiber (up to 86%) as well as manages to change the mode of failure of the beam from brittle to a more ductile manner.

  8. Electric-Pneumatic Actuator: A New Muscle for Locomotion

    Directory of Open Access Journals (Sweden)

    Maziar Ahmad Sharbafi

    2017-10-01

    Full Text Available A better understanding of how actuator design supports locomotor function may help develop novel and more functional powered assistive devices or robotic legged systems. Legged robots comprise passive parts (e.g., segments, joints and connections which are moved in a coordinated manner by actuators. In this study, we propose a novel concept of a hybrid electric-pneumatic actuator (EPA as an enhanced variable impedance actuator (VIA. EPA is consisted of a pneumatic artificial muscle (PAM and an electric motor (EM. In contrast to other VIAs, the pneumatic artificial muscle (PAM within the EPA provides not only adaptable compliance, but also an additional powerful actuator with muscle-like properties, which can be arranged in different combinations (e.g., in series or parallel to the EM. The novel hybrid actuator shares the advantages of both integrated actuator types combining precise control of EM with compliant energy storage of PAM, which are required for efficient and adjustable locomotion. Experimental and simulation results based on the new dynamic model of PAM support the hypothesis that combination of the two actuators can improve efficiency (energy and peak power and performance, while does not increase control complexity and weight, considerably. Finally, the experiments on EPA adapted bipedal robot (knee joint of the BioBiped3 robot show improved efficiency of the actuator at different frequencies.

  9. Dynamic Mechanical and Thermal Properties of Bagasse/Glass Fiber/Polypropylene Hybrid Composites

    Directory of Open Access Journals (Sweden)

    Mehdi Roohani

    2016-06-01

    Full Text Available This work aims to evaluate the thermal and dynamic mechanical properties of bagasse/glass fiber/polypropylene hybrid composites. Composites were prepared by the melt compounding method and their properties were characterized by differential scanning calorimetry (DSC and dynamic mechanical analysis (DMA. DSC results found that with incorporation of bagasse and glass fiber the melting temperature (Tm and the crystallisation temperature (Tc shift to higher temperatures and the degree of crystallinity (Xc increase. These findings suggest that the fibers played the role of a nucleating agent in composites. Dynamic mechanical analysis indicated that by the incorporation of bagasse and glass fiber into polypropylene, the storage modulus ( and the loss modulus ( increase whereas the mechanical loss factor (tanδ decrease. To assess the effect of reinforcement with increasing temperature, the effectiveness coefficient C was calculated at different temperature ranges and revealed that, at the elevated temperatures, improvement of mechanical properties due to the presence of fibers was more noticeable. The fiber-matrix adhesion efficiency determined by calculating of adhesion factor A in terms of the relative damping of the composite (tan δc and the polymer (tan δpand volume fraction of the fibers (Фf. Calculated adhesion factor A values indicated that by adding glass fiber to bagasse/polypropylene system, the fiber-matrix adhesion improve. Hybrid composite containing 25% bagasse and 15% glass fiber showed better fiber-matrix adhesion.

  10. Strain-mediated coupling in a quantum dot-mechanical oscillator hybrid system.

    Science.gov (United States)

    Yeo, I; de Assis, P-L; Gloppe, A; Dupont-Ferrier, E; Verlot, P; Malik, N S; Dupuy, E; Claudon, J; Gérard, J-M; Auffèves, A; Nogues, G; Seidelin, S; Poizat, J-Ph; Arcizet, O; Richard, M

    2014-02-01

    Recent progress in nanotechnology has allowed the fabrication of new hybrid systems in which a single two-level system is coupled to a mechanical nanoresonator. In such systems the quantum nature of a macroscopic degree of freedom can be revealed and manipulated. This opens up appealing perspectives for quantum information technologies, and for the exploration of the quantum-classical boundary. Here we present the experimental realization of a monolithic solid-state hybrid system governed by material strain: a quantum dot is embedded within a nanowire that features discrete mechanical resonances corresponding to flexural vibration modes. Mechanical vibrations result in a time-varying strain field that modulates the quantum dot transition energy. This approach simultaneously offers a large light-extraction efficiency and a large exciton-phonon coupling strength g0. By means of optical and mechanical spectroscopy, we find that g0/2 π is nearly as large as the mechanical frequency, a criterion that defines the ultrastrong coupling regime.

  11. Effects of surface roughening of Nafion 117 on the mechanical and physicochemical properties of ionic polymer-metal composite (IPMC) actuators

    Science.gov (United States)

    Wang, Yanjie; Zhu, Zicai; Liu, Jiayu; Chang, Longfei; Chen, Hualing

    2016-08-01

    In this paper, the surface of a Nafion membrane was roughened by the sandblasting method, mainly considering the change of sandblasting time and powder size. The roughened surfaces were characterized in terms of their topography from the confocal laser scanning microscope (CLSM) and SEM. The key surface parameters, such as Sa (the arithmetical mean deviation of the specified surface profile), SSA (the surface area ratio before and after roughening) and the area measurement on the histogram from the CLSM images, were extracted and evaluated from the roughened membranes. Also, the detailed change in surface and interfacial electrodes were measured and discussed together with the surface resistance, equivalent modulus, capacitance and performances of IPMC actuators based on the roughened membranes. The results show that a suitable sandblasting condition, resulting in the decrease in the bending stiffness and the increase in the interface area closely related to the capacitance, can effectively increase the electromechanical responses of IPMCs. Although the surface roughening by sandblasting caused a considerable lowering of mechanical strength, it was very effective for enlarging the interfacial area between Nafion membrane and the electrode layers, and for forming a penetrated electrode structure, which facilitated improvement of the surface resistance and capacitance characteristics of IPMCs. In this work, a quantitative relationship was built between the topography of Nafion membrane surface and electromechanical performance of IPMCs by means of sandblasting.

  12. Cruise and turning performance of an improved fish robot actuated by piezoceramic actuators

    Science.gov (United States)

    Nguyen, Quang Sang; Heo, Seok; Park, Hoon Cheol; Goo, Nam Seo; Byun, Doyoung

    2009-03-01

    The purpose of this study is improvement of a fish robot actuated by four light-weight piezocomposite actuators (LIPCAs). In the fish robot, we developed a new actuation mechanism working without any gear and thus the actuation mechanism was simple in fabrication. By using the new actuation mechanism, cross section of the fish robot became 30% smaller than that of the previous model. Performance tests of the fish robot in water were carried out to measure tail-beat angle, thrust force, swimming speed and turning radius for tail-beat frequencies from 1Hz to 5Hz. The maximum swimming speed of the fish robot was 7.7 cm/s at 3.9Hz tail-beat frequency. Turning experiment showed that swimming direction of the fish robot could be controlled with 0.41 m turning radius by controlling tail-beat angle.

  13. Parametric Analysis and Experimental Verification of a Hybrid Vibration Energy Harvester Combining Piezoelectric and Electromagnetic Mechanisms

    Directory of Open Access Journals (Sweden)

    Zhenlong Xu

    2017-06-01

    Full Text Available Considering coil inductance and the spatial distribution of the magnetic field, this paper developed an approximate distributed-parameter model of a hybrid energy harvester (HEH. The analytical solutions were compared with numerical solutions. The effects of load resistances, electromechanical coupling factors, mechanical damping ratio, coil parameters and size scale on performance were investigated. A meso-scale HEH prototype was fabricated, tested and compared with a stand-alone piezoelectric energy harvester (PEH and a stand-alone electromagnetic energy harvester (EMEH. The peak output power is 2.93% and 142.18% higher than that of the stand-alone PEH and EMEH, respectively. Moreover, its bandwidth is 108%- and 122.7%-times that of the stand-alone PEH and EMEH, respectively. The experimental results agreed well with the theoretical values. It is indicated that the linearized electromagnetic coupling coefficient is more suitable for low-level excitation acceleration. Hybrid energy harvesting contributes to widening the frequency bandwidth and improving energy conversion efficiency. However, only when the piezoelectric coupling effect is weak or medium can the HEH generate more power than the single-mechanism energy harvester. Hybrid energy harvesting can improve output power even at the microelectromechanical systems (MEMS scale. This study presents a more effective model for the performance evaluation and structure optimization of the HEH.

  14. The Mechanical Properties and Microstructure Characters of Hybrid Composite Geopolymers-Pineapple Fiber Leaves (PFL)

    Science.gov (United States)

    Amalia, N.; Hidayatullah, S.; Nurfadilla; Subaer

    2017-03-01

    The objective of this research is to study the influence of organic fibers on the mechanical properties and microstructure characters of hybrid composite geopolymers-pineapple fibers (PFL). Geopolymers were synthesized by using alkali activated of class C-fly ash added manually with short pineapple fiber leaves (PFL) and then cured at 60°C for 1 hour. The resulting composites were stored in open air for 28 days prior to mechanical and microstructure characterizations. The samples were subjected to compressive and flexural strength measurements, heat resistance as well as acid attack (1M H2SO4 solution). The microstructure of the composites were examined by using Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS). The measurement showed that the addition of pineapple fibers was able to improve the compressive and flexural strength of geopolymers. The resulting hybrid composites were able to resist fire to a maximum temperature of 1500°C. SEM examination showed the presence of good bond between geopolymer matrix and pineapple fibers. It was also found that there were no chemical constituents of geopolymers leached out during acid liquid treatment. It is concluded that hybrid composite geopolymers-pineapple fibers are potential composites for wide range applications.

  15. Electrical actuators applications and performance

    CERN Document Server

    De Fornel, Bernard

    2013-01-01

    This helpful resource covers a large range of information regarding electrical actuators. In particular, robustness, a very problematic issue, is fully explored in a dedicated chapter. The text also deals with he estimate of non-measurable mechanical variables by examining the estimate of load moment, then observation of the positioning of a command without mechanical sensor. Finally, it examines the conditions needed to measure variables and real implementation of numerical algorithms. This is a key working resource for electrical engineers.

  16. CSP-based chemical kinetics mechanisms simplification strategy for non-premixed combustion: An application to hybrid rocket propulsion

    KAUST Repository

    Ciottoli, Pietro P.; Malpica Galassi, Riccardo; Lapenna, Pasquale E.; Leccese, G.; Bianchi, D.; Nasuti, F.; Creta, F.; Valorani, M.

    2017-01-01

    A set of simplified chemical kinetics mechanisms for hybrid rocket applications using gaseous oxygen (GOX) and hydroxyl-terminated polybutadiene (HTPB) is proposed. The starting point is a 561-species, 2538-reactions, detailed chemical kinetics

  17. 3D printed soft parallel actuator

    Science.gov (United States)

    Zolfagharian, Ali; Kouzani, Abbas Z.; Khoo, Sui Yang; Noshadi, Amin; Kaynak, Akif

    2018-04-01

    This paper presents a 3-dimensional (3D) printed soft parallel contactless actuator for the first time. The actuator involves an electro-responsive parallel mechanism made of two segments namely active chain and passive chain both 3D printed. The active chain is attached to the ground from one end and constitutes two actuator links made of responsive hydrogel. The passive chain, on the other hand, is attached to the active chain from one end and consists of two rigid links made of polymer. The actuator links are printed using an extrusion-based 3D-Bioplotter with polyelectrolyte hydrogel as printer ink. The rigid links are also printed by a 3D fused deposition modelling (FDM) printer with acrylonitrile butadiene styrene (ABS) as print material. The kinematics model of the soft parallel actuator is derived via transformation matrices notations to simulate and determine the workspace of the actuator. The printed soft parallel actuator is then immersed into NaOH solution with specific voltage applied to it via two contactless electrodes. The experimental data is then collected and used to develop a parametric model to estimate the end-effector position and regulate kinematics model in response to specific input voltage over time. It is observed that the electroactive actuator demonstrates expected behaviour according to the simulation of its kinematics model. The use of 3D printing for the fabrication of parallel soft actuators opens a new chapter in manufacturing sophisticated soft actuators with high dexterity and mechanical robustness for biomedical applications such as cell manipulation and drug release.

  18. A mechanically enhanced hybrid nano-stratified barrier with a defect suppression mechanism for highly reliable flexible OLEDs.

    Science.gov (United States)

    Jeong, Eun Gyo; Kwon, Seonil; Han, Jun Hee; Im, Hyeon-Gyun; Bae, Byeong-Soo; Choi, Kyung Cheol

    2017-05-18

    Understanding the mechanical behaviors of encapsulation barriers under bending stress is important when fabricating flexible organic light-emitting diodes (FOLEDs). The enhanced mechanical characteristics of a nano-stratified barrier were analyzed based on a defect suppression mechanism, and then experimentally demonstrated. Following the Griffith model, naturally-occurring cracks, which were caused by Zn etching at the interface of the nano-stratified structure, can curb the propagation of defects. Cross-section images after bending tests provided remarkable evidence to support the existence of a defect suppression mechanism. Many visible cracks were found in a single Al 2 O 3 layer, but not in the nano-stratified structure, due to the mechanism. The nano-stratified structure also enhanced the barrier's physical properties by changing the crystalline phase of ZnO. In addition, experimental results demonstrated the effect of the mechanism in various ways. The nano-stratified barrier maintained a low water vapor transmission rate after 1000 iterations of a 1 cm bending radius test. Using this mechanically enhanced hybrid nano-stratified barrier, FOLEDs were successfully encapsulated without losing mechanical or electrical performance. Finally, comparative lifetime measurements were conducted to determine reliability. After 2000 hours of constant current driving and 1000 iterations with a 1 cm bending radius, the FOLEDs retained 52.37% of their initial luminance, which is comparable to glass-lid encapsulation, with 55.96% retention. Herein, we report a mechanically enhanced encapsulation technology for FOLEDs using a nano-stratified structure with a defect suppression mechanism.

  19. Design, processing and characterization of mechanically alloyed galfenol & lightly rare-earth doped FeGa alloys as smart materials for actuators and transducers

    Science.gov (United States)

    Taheri, Parisa

    Smart materials find a wide range of application areas due to their varied response to external stimuli. The different areas of application can be in our day to day life, aerospace, civil engineering applications, and mechatronics to name a few. Magnetostrictive materials are a class of smart materials that can convert energy between the magnetic and elastic states. Galfenol is a magnetostrictive alloy comprised primarily of the elements iron (Fe) and gallium (Ga). Galfenol exhibits a unique combination of mechanical and magnetostrictive (magnetic) properties that legacy smart materials do not. Galfenol's ability to function while in tension, mechanical robustness and high Curie temperature (600 °C) is attracting interest for the alloy's use in mechanically harsh and elevated temperature environments. Applications actively being investigated include transducers for down-hole use, next-generation fuel injectors, sensing, and energy harvesting devices. Understanding correlations between microstructure, electronic structure, and functional response is key to developing novel magnetostrictive materials for sensor and actuator technologies. To this end, in the first part of this thesis we report successful fabrication and investigation of magnetic and magnetostrictive properties of mechanically alloyed Fe81Ga19 compounds. For the first time, we could measure magnetostrictive properties of mechanically alloyed FeGa compounds. A maximum saturation magnetostriction of 41 ppm was achieved which is comparable to those measured from polycrystalline FeGa alloys prepared by other processing techniques, namely gas atomization and cold rolling. Overall, this study demonstrates the feasibility of large-scale production of FeGa polycrystalline alloys powders by a simple and cost-effective mechanical alloying technique. In the second part of this work, we report for the first time, experimental results pertaining to successful fabrication and advanced characterization of a series

  20. Reliable Actuator for Cryo Propellant Fluid Control, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Fluid handling applications in cryogenic and extreme environments require reliable actuation technology that can handle extreme temperatures, mechanical bind-up from...

  1. Mechanical Actuation Systems for the Phenotype Commitment of Stem Cell-Based Tendon and Ligament Tissue Substitutes.

    Science.gov (United States)

    Govoni, Marco; Muscari, Claudio; Lovecchio, Joseph; Guarnieri, Carlo; Giordano, Emanuele

    2016-04-01

    High tensile forces transmitted by tendons and ligaments make them susceptible to tearing or complete rupture. The present standard reparative technique is the surgical implantation of auto- or allografts, which often undergo failure.Currently, different cell types and biomaterials are used to design tissue engineered substitutes. Mechanical stimulation driven by dedicated devices can precondition these constructs to a remarkable degree, mimicking the local in vivo environment. A large number of dynamic culture instruments have been developed and many appealing results collected. Of the cells that have been used, tendon stem cells are the most promising for a reliable stretch-induced tenogenesis, but their reduced availability represents a serious limitation to upscaled production. Biomaterials used for scaffold fabrication include both biological molecules and synthetic polymers, the latter being improved by nanotechnologies which reproduce the architecture of native tendons. In addition to cell type and scaffold material, other variables which must be defined in mechanostimulation protocols are the amplitude, frequency, duration and direction of the applied strain. The ideal conditions seem to be those producing intermittent tension rather than continuous loading. In any case, all physical parameters must be adapted to the specific response of the cells used and the tensile properties of the scaffold. Tendon/ligament grafts in animals usually have the advantage of mechanical preconditioning, especially when uniaxial cyclic forces are applied to cells engineered into natural or decellularized scaffolds. However, due to the scarcity of in vivo research, standard protocols still need to be defined for clinical applications.

  2. PRICING ELECTRIC POWER UNDER A HYBRID WHOLESALE MECHANISM: EVALUATING THE TURKISH ELECTRICITY MARKET

    Directory of Open Access Journals (Sweden)

    Hatice Karahan

    2013-01-01

    Full Text Available During the restructuring process, Turkish electricity sector has gone through significant changes both in wholesale and retail markets. In this framework, the Market Financial Settlement Mechanism established for handling market imbalances has become a spot market in time. So, it can be claimed that the wholesale electricity market in Turkey is a hybrid mechanism composed of bilateral contracts and the balancing market. On the other hand, the main target of liberalization program is providing consumers with affordable electric power. Hence, this study attempts to explore the link between retail tariffs for ineligible consumers and prices in the two wholesale mechanisms, in the period after the launch of the day-ahead market. Findings suggest that regulated wholesale prices are more effective in the determination of end-user prices, whereas unregulated ones might have a price reduction effect in case the free market dominates. However, the volatility in spot market prices implies that the sector would better continue with the hybrid mechanism for quite some time.

  3. Mechanical properties and production quality of hand-layup and vacuum infusion processed hybrid composite materials for GFRP marine structures

    Science.gov (United States)

    Kim, Sang-Young; Shim, Chun Sik; Sturtevant, Caleb; Kim, Dave (Dae-Wook); Song, Ha Cheol

    2014-09-01

    Glass Fiber Reinforced Plastic (GFRP) structures are primarily manufactured using hand lay-up or vacuum infusion techniques, which are cost-effective for the construction of marine vessels. This paper aims to investigate the mechanical properties and failure mechanisms of the hybrid GFRP composites, formed by applying the hand lay-up processed exterior and the vacuum infusion processed interior layups, providing benefits for structural performance and ease of manufacturing. The hybrid GFRP composites contain one, two, and three vacuum infusion processed layer sets with consistent sets of hand lay-up processed layers. Mechanical properties assessed in this study include tensile, compressive and in-plane shear properties. Hybrid composites with three sets of vacuum infusion layers showed the highest tensile mechanical properties while those with two sets had the highest mechanical properties in compression. The batch homogeneity, for the GFRP fabrication processes, is evaluated using the experimentally obtained mechanical properties

  4. Mechanical properties and production quality of hand-layup and vacuum infusion processed hybrid composite materials for GFRP marine structures

    Directory of Open Access Journals (Sweden)

    Kim Sang-Young

    2014-09-01

    Full Text Available Glass Fiber Reinforced Plastic (GFRP structures are primarily manufactured using hand lay-up or vacuum infusion techniques, which are cost-effective for the construction of marine vessels. This paper aims to investigate the mechanical properties and failure mechanisms of the hybrid GFRP composites, formed by applying the hand lay-up processed exterior and the vacuum infusion processed interior layups, providing benefits for structural performance and ease of manufacturing. The hybrid GFRP composites contain one, two, and three vacuum infusion processed layer sets with consistent sets of hand lay-up processed layers. Mechanical properties assessed in this study include tensile, compressive and in-plane shear properties. Hybrid composites with three sets of vacuum infusion layers showed the highest tensile mechanical properties while those with two sets had the highest mechanical properties in compression. The batch homogeneity, for the GFRP fabrication processes, is evaluated using the experimentally obtained mechanical properties

  5. Mechanical properties and production quality of hand-layup and vacuum infusion processed hybrid composite materials for GFRP marine structures

    Directory of Open Access Journals (Sweden)

    Sang-Young Kim

    2014-09-01

    Full Text Available Glass Fiber Reinforced Plastic (GFRP structures are primarily manufactured using hand lay-up or vacuum infusion techniques, which are cost-effective for the construction of marine vessels. This paper aims to investigate the mechanical properties and failure mechanisms of the hybrid GFRP composites, formed by applying the hand lay-up processed exterior and the vacuum infusion processed interior layups, providing benefits for structural performance and ease of manufacturing. The hybrid GFRP composites contain one, two, and three vacuum infusion processed layer sets with consistent sets of hand lay-up processed layers. Mechanical properties assessed in this study include tensile, compressive and in-plane shear properties. Hybrid composites with three sets of vacuum infusion layers showed the highest tensile mechanical properties while those with two sets had the highest mechanical properties in compression. The batch homogeneity, for the GFRP fabrication processes, is evaluated using the experimentally obtained mechanical properties.

  6. Magnetic Actuation of Biological Systems

    Science.gov (United States)

    Lauback, Stephanie D.

    Central to the advancement of many biomedical and nanotechnology capabilities is the capacity to precisely control the motion of micro and nanostructures. These applications range from single molecule experiments to cell isolation and separation, to drug delivery and nanomachine manipulation. This dissertation focuses on actuation of biological micro- and nano-entities through the use of weak external magnetic fields, superparamagnetic beads, and ferromagnetic thin films. The magnetic platform presents an excellent method for actuation of biological systems due to its ability to directly control the motion of an array of micro and nanostructures in real-time with calibrated picoNewton forces. The energy landscape of two ferromagnetic thin film patterns (disks and zigzag wires) is experimentally explored and compared to corresponding theoretical models to quantify the applied forces and trajectories of superparamagnetic beads due to the magnetic traps. A magnetic method to directly actuate DNA nanomachines in real-time with nanometer resolution and sub-second response times using micromagnetic control was implemented through the use of stiff DNA micro-levers which bridged the large length scale mismatch between the micro-actuator and the nanomachine. Compared to current alternative methods which are limited in the actuation speeds and the number of reconfiguration states of DNA constructs, this magnetic approach enables fast actuation (˜ milliseconds) and reconfigurable conformations achieved through a continuous range of finely tuned steps. The system was initially tested through actuation of the stiff arm tethered to the surface, and two prototype DNA nanomachines (rotor and hinge) were successfully actuated using the stiff mechanical lever. These results open new possibilities in the development of functional robotic systems at the molecular scale. In exploiting the use of DNA stiff levers, a new technique was also developed to investigate the emergence of the

  7. Hybrid printing of mechanically and biologically improved constructs for cartilage tissue engineering applications

    International Nuclear Information System (INIS)

    Xu Tao; Binder, Kyle W; Albanna, Mohammad Z; Dice, Dennis; Zhao Weixin; Yoo, James J; Atala, Anthony

    2013-01-01

    Bioprinting is an emerging technique used to fabricate viable, 3D tissue constructs through the precise deposition of cells and hydrogels in a layer-by-layer fashion. Despite the ability to mimic the native properties of tissue, printed 3D constructs that are composed of naturally-derived biomaterials still lack structural integrity and adequate mechanical properties for use in vivo, thus limiting their development for use in load-bearing tissue engineering applications, such as cartilage. Fabrication of viable constructs using a novel multi-head deposition system provides the ability to combine synthetic polymers, which have higher mechanical strength than natural materials, with the favorable environment for cell growth provided by traditional naturally-derived hydrogels. However, the complexity and high cost associated with constructing the required robotic system hamper the widespread application of this approach. Moreover, the scaffolds fabricated by these robotic systems often lack flexibility, which further restrict their applications. To address these limitations, advanced fabrication techniques are necessary to generate complex constructs with controlled architectures and adequate mechanical properties. In this study, we describe the construction of a hybrid inkjet printing/electrospinning system that can be used to fabricate viable tissues for cartilage tissue engineering applications. Electrospinning of polycaprolactone fibers was alternated with inkjet printing of rabbit elastic chondrocytes suspended in a fibrin–collagen hydrogel in order to fabricate a five-layer tissue construct of 1 mm thickness. The chondrocytes survived within the printed hybrid construct with more than 80% viability one week after printing. In addition, the cells proliferated and maintained their basic biological properties within the printed layered constructs. Furthermore, the fabricated constructs formed cartilage-like tissues both in vitro and in vivo as evidenced by the

  8. Piezoelectric multilayer actuator life test.

    Science.gov (United States)

    Sherrit, Stewart; Bao, Xiaoqi; Jones, Christopher M; Aldrich, Jack B; Blodget, Chad J; Moore, James D; Carson, John W; Goullioud, Renaud

    2011-04-01

    Potential NASA optical missions such as the Space Interferometer Mission require actuators for precision positioning to accuracies of the order of nanometers. Commercially available multilayer piezoelectric stack actuators are being considered for driving these precision mirror positioning mechanisms. These mechanisms have potential mission operational requirements that exceed 5 years for one mission life. To test the feasibility of using these commercial actuators for these applications and to determine their reliability and the redundancy requirements, a life test study was undertaken. The nominal actuator requirements for the most critical actuators on the Space Interferometry Mission (SIM) in terms of number of cycles was estimated from the Modulation Optics Mechanism (MOM) and Pathlength control Optics Mechanism (POM) and these requirements were used to define the study. At a nominal drive frequency of 250 Hz, one mission life is calculated to be 40 billion cycles. In this study, a set of commercial PZT stacks configured in a potential flight actuator configuration (pre-stressed to 18 MPa and bonded in flexures) were tested for up to 100 billion cycles. Each test flexure allowed for two sets of primary and redundant stacks to be mechanically connected in series. The tests were controlled using an automated software control and data acquisition system that set up the test parameters and monitored the waveform of the stack electrical current and voltage. The samples were driven between 0 and 20 V at 2000 Hz to accelerate the life test and mimic the voltage amplitude that is expected to be applied to the stacks during operation. During the life test, 10 primary stacks were driven and 10 redundant stacks, mechanically in series with the driven stacks, were open-circuited. The stroke determined from a strain gauge, the temperature and humidity in the chamber, and the temperature of each individual stack were recorded. Other properties of the stacks, including the

  9. Thermal, mechanical, and physical properties of seaweed/sugar palm fibre reinforced thermoplastic sugar palm Starch/Agar hybrid composites.

    Science.gov (United States)

    Jumaidin, Ridhwan; Sapuan, Salit M; Jawaid, Mohammad; Ishak, Mohamad R; Sahari, Japar

    2017-04-01

    The aim of this research is to investigate the effect of sugar palm fibre (SPF) on the mechanical, thermal and physical properties of seaweed/thermoplastic sugar palm starch agar (TPSA) composites. Hybridized seaweed/SPF filler at weight ratio of 25:75, 50:50 and 75:25 were prepared using TPSA as a matrix. Mechanical, thermal and physical properties of hybrid composites were carried out. Obtained results indicated that hybrid composites display improved tensile and flexural properties accompanied with lower impact resistance. The highest tensile (17.74MPa) and flexural strength (31.24MPa) was obtained from hybrid composite with 50:50 ratio of seaweed/SPF. Good fibre-matrix bonding was evident in the scanning electron microscopy (SEM) micrograph of the hybrid composites' tensile fracture. Fourier transform infrared spectroscopy (FT-IR) analysis showed increase in intermolecular hydrogen bonding following the addition of SPF. Thermal stability of hybrid composites was enhanced, indicated by a higher onset degradation temperature (259°C) for 25:75 seaweed/SPF composites than the individual seaweed composites (253°C). Water absorption, thickness swelling, water solubility, and soil burial tests showed higher water and biodegradation resistance of the hybrid composites. Overall, the hybridization of SPF with seaweed/TPSA composites enhances the properties of the biocomposites for short-life application; that is, disposable tray, plate, etc. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Microstructural evolution and mechanical properties of Mg composites containing nano-B4C hybridized micro-Ti particulates

    International Nuclear Information System (INIS)

    Sankaranarayanan, S.; Sabat, R.K.; Jayalakshmi, S.; Suwas, S.; Gupta, M.

    2014-01-01

    In this work, the microstructural evolution and mechanical properties of extruded Mg composites containing micro-Ti particulates hybridized with varying contents of nano-B 4 C are investigated, and compared with Mg-5.6Ti. Microstructural characterization showed the presence of uniformly distributed micro-Ti particles embedded with nano-B 4 C particulates that resulted in significant grain refinement. Electron back scattered diffraction (EBSD) analyses of Mg-(5.6Ti + x-B 4 C) BM hybrid composites showed that the addition of hybridized particle resulted in relatively more recrystallized grains, realignment of basal planes and extension of weak basal fibre texture when compared to Mg-5.6Ti. The evaluation of mechanical properties indicated improved strength with ductility retention in Mg-(5.6Ti + x-B 4 C) BM hybrid composites. When compared to Mg-5.6Ti, the superior strength properties of the Mg-(5.6Ti + x-B 4 C) BM hybrid composites are attributed to the presence of nano-reinforcements, the uniform distribution of the hybridized particles, better interfacial bonding between the matrix and the reinforcement particles and the matrix grain refinement achieved by nano-B 4 C addition. The ductility enhancement obtained in hybrid composites can be attributed to the fibre texture spread and favourable basal plane orientation achieved due to nano B 4 C addition. - Highlights: • Micro-Ti particulates are hybridized with varying weight fractions of nano-B 4 C. • The hybrid mixture was used as hybrid reinforcements in magnesium. • Microstructure and mechanical properties of Mg-(5.6Ti + x-B 4 C) BM are compared with Mg-5.6Ti. • Electron back scattered diffraction (EBSD) analysis conducted to study the microtexture evolution

  11. Mechanical and water absorption behaviour of banana/sisal reinforced hybrid composites

    International Nuclear Information System (INIS)

    Venkateshwaran, N.; ElayaPerumal, A.; Alavudeen, A.; Thiruchitrambalam, M.

    2011-01-01

    Highlights: → It explores the utilization of waste banana fiber. → Improving the mechanical property by hybridization. → Results show its usefulness to low cost application. -- Abstract: The tensile, flexural, impact and water absorption tests were carried out using banana/epoxy composite material. Initially, optimum fiber length and weight percentage were determined. To improve the mechanical properties, banana fiber was hybridised with sisal fiber. This study showed that addition of sisal fiber in banana/epoxy composites of up to 50% by weight results in increasing the mechanical properties and decreasing the moisture absorption property. Morphological analysis was carried out to observe fracture behaviour and fiber pull-out of the samples using scanning electron microscope.

  12. Observation of the mechanisms causing two kinds of undercut during laser hybrid arc welding

    Energy Technology Data Exchange (ETDEWEB)

    Karlsson, Jan, E-mail: jan.karlsson@ltu.se [Lulea University of Technology, Dept. TVM, SE-971 87 Lulea (Sweden); Norman, Peter; Kaplan, Alexander F.H. [Lulea University of Technology, Dept. TVM, SE-971 87 Lulea (Sweden); Rubin, Per [Rubin-Materialteknik, Gullhoenevaegen 13 97596 Lulea (Sweden); Lamas, Javier [Lulea University of Technology, Dept. TVM, SE-971 87 Lulea (Sweden); Centro Tecnoloxico do Naval Galego, Ferrol 15590 (A Coruna) (Spain); Yanez, Armando [Centro de Investigacions Tecnoloxicas, Universidade da Coruna, Ferrol 15403 (A Coruna) (Spain)

    2011-06-15

    Two different kinds of undercut were identified when laser hybrid welding hot rolled HSLA-steel in either the as-rolled condition or with the top surface mill scale removed. The presence of mill scale on the steel surface was found to give a sharp angled undercut combined with a sharp oxide inclusion at the edge of the weld which would have the same mechanical effect as a crack in this position. Removal of the surface oxides before welding resulted in the elimination of the oxide inclusions and a more rounded undercut geometry indicative of superior mechanical properties, particularly fatigue life. The mechanisms of the formation of both types of undercut have been analysed by high speed photography and SEM.

  13. An Engineered Kinetic Amplification Mechanism for Single Nucleotide Variant Discrimination by DNA Hybridization Probes.

    Science.gov (United States)

    Chen, Sherry Xi; Seelig, Georg

    2016-04-20

    Even a single-nucleotide difference between the sequences of two otherwise identical biological nucleic acids can have dramatic functional consequences. Here, we use model-guided reaction pathway engineering to quantitatively improve the performance of selective hybridization probes in recognizing single nucleotide variants (SNVs). Specifically, we build a detection system that combines discrimination by competition with DNA strand displacement-based catalytic amplification. We show, both mathematically and experimentally, that the single nucleotide selectivity of such a system in binding to single-stranded DNA and RNA is quadratically better than discrimination due to competitive hybridization alone. As an additional benefit the integrated circuit inherits the property of amplification and provides at least 10-fold better sensitivity than standard hybridization probes. Moreover, we demonstrate how the detection mechanism can be tuned such that the detection reaction is agnostic to the position of the SNV within the target sequence. in contrast, prior strand displacement-based probes designed for kinetic discrimination are highly sensitive to position effects. We apply our system to reliably discriminate between different members of the let-7 microRNA family that differ in only a single base position. Our results demonstrate the power of systematic reaction network design to quantitatively improve biotechnology.

  14. Nanocellulose composites with enhanced interfacial compatibility and mechanical properties using a hybrid-toughened epoxy matrix.

    Science.gov (United States)

    Kuo, Pei-Yu; Barros, Luizmar de Assis; Yan, Ning; Sain, Mohini; Qing, Yan; Wu, Yiqiang

    2017-12-01

    Although there is a growing interest in utilizing nanocellulose fibres (NCFs) based composites for achieving a higher sustainability, mechanical performance of these composites is limited due to the poor compatibility between fibre reinforcement and polymer matrices. Here we developed a bio-nanocomposite with an enhanced fibre/resin interface using a hybrid-toughened epoxy. A strong reinforcing effect of NCFs was achieved, demonstrating an increase up to 88% in tensile strength and 298% in tensile modulus as compared to neat petro-based P-epoxy. The toughness of neat P-epoxy was improved by 84% with the addition of 10wt% bio-based E-epoxy monomers, which also mitigated the amount of usage of bisphenol A (BPA). The morphological analyses showed that the hybrid epoxy improved the resin penetration and fibre distribution significantly in the resulting composites. Thus, our findings demonstrated the promise of developing sustainable and high performance epoxy composites combing NCFs with a hybrid petro-based and bio-based epoxy resin system. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Mechanical properties evaluation of single and hybrid composites polyester reinforced bamboo, PALF and coir fiber

    Science.gov (United States)

    Rihayat, T.; Suryani, S.; Fauzi, T.; Agusnar, H.; Wirjosentono, B.; Syafruddin; Helmi; Zulkifli; Alam, P. N.; Sami, M.

    2018-03-01

    This study aims to determine the composition fiber natural of bamboo, pineapple leaf and coir in single and hybrid composite to see the best characteristics of tensile strength and flexural test by using a Universal Testing Machine (UTM) and observe the effect on the microstructure of the composite through optical and scanning electron microscopy. Bamboo, Palf and coir have synthesis from natural fiber was used as reinforcement in polyester composite using hand lay up or a hot-compression moulding while filler:matrix was used (45%:55wt.%, 70%:30wt.% and 15%:85wt.%). From the variation of the volume fraction between filler and matrix show that mechanical properties of composites increased with increasing amount of filler in the matrix. This is evidenced by the high mechanical properties A:B:C/Ps in compositions 45%: 55wt.% 136 Mpa while flexural strength 93 N and good structure surface morphology. This research has produced a hybrid composite materials that have high mechanical properties and bending compared with conventional synthetic fibers and other materials.

  16. Nanowire Structured Hybrid Cell for Concurrently Scavenging Solar and Mechanical Energies

    KAUST Repository

    Xu, Chen

    2009-04-29

    Conversion cells for harvesting solar energy and mechanical energy are usually separate and independent entities that are designed and built following different physical principles. Developing a technology that harvests multiple-type energies in forms such as sun light and mechanical around the clock is desperately desired for fully utilizing the energies available in our living environment. We report a hybrid cell that is intended for simultaneously harvesting solar and mechanical energies. Using aligned ZnO nanowire arrays grown on surfaces of a flat substrate, a dye-sensitized solar cell is integrated with a piezoelectric nanogenerator. The former harvests solar energy irradiating on the top, and the latter harvests ultrasonic wave energy from the surrounding. The two energy harvesting approaches can work simultaneously or individually, and they can be integrated in parallel and serial for raising the output current and voltage, respectively, as well as power. It is found that the voltage output from the solar cell can be used to raise the output voltage of the nanogenerator, providing an effective approach for effectively storing and utilizing the power generated by the nanogenerator. Our study demonstrates a new approach for concurrently harvesting multiple types of energies using an integrated hybrid cell so that the energy resources can be effectively and complementary utilized whenever and wherever one or all of them is available. © 2009 American Chemical Society.

  17. A net normal dispersion all-fiber laser using a hybrid mode-locking mechanism

    International Nuclear Information System (INIS)

    Xu, Bo; Martinez, Amos; Yamashita, Shinji; Set, Sze Yun; Goh, Chee Seong

    2014-01-01

    We propose and demonstrate an all-fiber, dispersion-mapped, erbium-doped fiber laser with net normal dispersion generating dissipative solitons. The laser is mode-locked by a hybrid mode-locking mechanism consisting of a nonlinear amplifying loop mirror and a carbon nanotube saturable absorber. We achieve self-starting, mode-locked operation generating 2.75 nJ pulses at a fundamental repetition rate of 10.22 MHz with remarkable long term stability. (letter)

  18. Elastomer Nanocomposites Based on Butadiene Rubber, Nanoclay and Epoxy-Polyester Hybrid: Microstructure and Mechanical Properties

    OpenAIRE

    Sepideh Zoghi; Ghasem Naderi; Gholam Reza Bakhshandeh; Morteza Ehsani; Shirin Shokoohi

    2013-01-01

    Nanocomposites based on butadiene rubber (BR), (0, 3, 5 and 7 phr) organoclay (Cloisite 15A) and (0, 10, 20, 30, 40 phr) powder coating wastes, i.e., epoxypolyester hybrid (EPH) were prepared using a laboratory-scale internal mixer in order to study the effect of organoclay and EPH content on the mechanical and morphological properties of the nanocomposite samples. Cure characteristics of the prepared compounds including optimum cure time (t90) and scorch time (t5) depicted a decrease in both...

  19. Hydrogen storage in hybrid of layered double hydroxides/reduced graphene oxide using spillover mechanism

    International Nuclear Information System (INIS)

    Ensafi, Ali A.; Jafari-Asl, Mehdi; Nabiyan, Afshin; Rezaei, Behzad; Dinari, Mohammad

    2016-01-01

    New efficient hydrogen storage hybrids were fabricated based on hydrogen spillover mechanism, including chemisorptions and dissociation of H_2 on the surface of LDH (layered double hydroxides) and diffusion of H to rGO (reduced graphene oxide). The structures and compositions of all of the hybrids (LDHs/rGO) have been verified using different methods including transmission electron microscopy, X ray diffraction spectroscopy, infrared spectroscopy and Brunauer–Emmett–Teller analysis. Then, the abilities of the LDHs/rGOs, as hydrogen spillover, were investigated by electrochemical methods. In addition, the LDHs/rGOs were decorated with palladium, using redox replacement process, and their hydrogen spillover properties were studied. The results showed that the hydrogen adsorption/desorption kinetics, hydrogen storage capacities and stabilities of Pd"#LDH/rGOs are better than Pd/rGO. Finally presence of different polymers (synthesis with monomers, 4–aminophenol, 4–aminothiophenol, o-phenylenediamine and p-phenylenediamine) at the surface of the Pd#LDH/rGOs on hydrogen storage were studied. The results showed that presence of o-phenylenediamine and p-phenylenediamine improves the kinetics of the hydrogen adsorption/desorption and increase the capacity of the hydrogen storage. - Highlights: • Efficient hydrogen storage sorbents are introduced. • The sorbents are synthesized based on hybrids of layered double hydroxide. • The compositions of all of the hybrids are verified using different methods. • Pd nanoparticles modified nanohybrids are investigated for hydrogen storage. • Presence of different polymers beside the hydrogen sorbents are investigated.

  20. Multilayer Piezoelectric Stack Actuator Characterization

    Science.gov (United States)

    Sherrit, Stewart; Jones, Christopher M.; Aldrich, Jack B.; Blodget, Chad; Bao, Xioaqi; Badescu, Mircea; Bar-Cohen, Yoseph

    2008-01-01

    Future NASA missions are increasingly seeking to use actuators for precision positioning to accuracies of the order of fractions of a nanometer. For this purpose, multilayer piezoelectric stacks are being considered as actuators for driving these precision mechanisms. In this study, sets of commercial PZT stacks were tested in various AC and DC conditions at both nominal and extreme temperatures and voltages. AC signal testing included impedance, capacitance and dielectric loss factor of each actuator as a function of the small-signal driving sinusoidal frequency, and the ambient temperature. DC signal testing includes leakage current and displacement as a function of the applied DC voltage. The applied DC voltage was increased to over eight times the manufacturers' specifications to investigate the correlation between leakage current and breakdown voltage. Resonance characterization as a function of temperature was done over a temperature range of -180C to +200C which generally exceeded the manufacturers' specifications. In order to study the lifetime performance of these stacks, five actuators from one manufacturer were driven by a 60volt, 2 kHz sine-wave for ten billion cycles. The tests were performed using a Lab-View controlled automated data acquisition system that monitored the waveform of the stack electrical current and voltage. The measurements included the displacement, impedance, capacitance and leakage current and the analysis of the experimental results will be presented.

  1. MEMS fluidic actuator

    Science.gov (United States)

    Kholwadwala, Deepesh K [Albuquerque, NM; Johnston, Gabriel A [Trophy Club, TX; Rohrer, Brandon R [Albuquerque, NM; Galambos, Paul C [Albuquerque, NM; Okandan, Murat [Albuquerque, NM

    2007-07-24

    The present invention comprises a novel, lightweight, massively parallel device comprising microelectromechanical (MEMS) fluidic actuators, to reconfigure the profile, of a surface. Each microfluidic actuator comprises an independent bladder that can act as both a sensor and an actuator. A MEMS sensor, and a MEMS valve within each microfluidic actuator, operate cooperatively to monitor the fluid within each bladder, and regulate the flow of the fluid entering and exiting each bladder. When adjacently spaced in a array, microfluidic actuators can create arbitrary surface profiles in response to a change in the operating environment of the surface. In an embodiment of the invention, the profile of an airfoil is controlled by independent extension and contraction of a plurality of actuators, that operate to displace a compliant cover.

  2. Soft buckling actuators

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Dian; Whitesides, George M.

    2017-12-26

    A soft actuator is described, including: a rotation center having a center of mass; a plurality of bucklable, elastic structural components each comprising a wall defining an axis along its longest dimension, the wall connected to the rotation center in a way that the axis is offset from the center of mass in a predetermined direction; and a plurality of cells each disposed between two adjacent bucklable, elastic structural components and configured for connection with a fluid inflation or deflation source; wherein upon the deflation of the cell, the bucklable, elastic structural components are configured to buckle in the predetermined direction. A soft actuating device including a plurality of the soft actuators and methods of actuation using the soft actuator or soft actuating device disclosed herein are also described.

  3. Experimental and computational study of the effect of breath-actuated mechanism built in the NEXThaler® dry powder inhaler.

    Science.gov (United States)

    Farkas, Árpád; Lewis, David; Church, Tanya; Tweedie, Alan; Mason, Francesca; Haddrell, Allen E; Reid, Jonathan P; Horváth, Alpár; Balásházy, Imre

    2017-11-25

    The breath-actuated mechanism (BAM) is a mechanical unit included in NEXThaler ® with the role of delaying the emission of the drug until the inhalation flow rate of the patient is sufficiently high to detach the drug particles from their carriers. The main objective of this work was to analyse the effect of the presence of BAM on the size distribution of the emitted drug and its airway deposition efficiency and distribution. Study of the hygroscopic growth of the emitted drug particles and its effect on the deposition was another goal of this study. Size distributions of Foster ® NEXThaler ® drug particles emitted by dry powder inhalers with and without BAM have been measured by a Next Generation Impactor. Three characteristic inhalation profiles of asthmatic patients (low, moderate and high flow rates) were used for both experimental and modelling purposes. Particle hygroscopic growth was determined by a new method, where experimental measurements are combined with simulations. Upper airway and lung deposition fractions were computed assuming 5s and 10s breath-hold times. By the inclusion of BAM the fine particle fraction of the steroid component increased from 24 to 30% to 47-51%, while that of bronchodilator from 25-34% to 52-55%. The predicted upper airway steroid and bronchodilator doses decreased from about 60% to 35-40% due to BAM. At the same time, predicted lung doses increased from about 20%-35% (steroid) and from 22% to 38% (bronchodilator) for the moderate flow profile and from about 25% to 40% (steroid) and from 29% to 47% (bronchodilator) for the high inhalation flow profile. Although BDP and FF upper airway doses decreased by a factor of about two when BAM was present, lung doses of both components were about the same in the BAM and no-BAM configurations at the weakest flow profile. However, lung dose increased by 2-3% even for this profile when hygroscopic growth was taken into account. In conclusion, the NEXThaler ® BAM mechanism is a unique

  4. Magnetic actuators and sensors

    CERN Document Server

    Brauer, John R

    2014-01-01

    An accessible, comprehensive guide on magnetic actuators and sensors, this fully updated second edition of Magnetic Actuators and Sensors includes the latest advances, numerous worked calculations, illustrations, and real-life applications. Covering magnetics, actuators, sensors, and systems, with updates of new technologies and techniques, this exemplary learning tool emphasizes computer-aided design techniques, especially magnetic finite element analysis, commonly used by today's engineers. Detailed calculations, numerous illustrations, and discussions of discrepancies make this text an inva

  5. Development of thermal actuators with multi-locking positions

    Science.gov (United States)

    Luo, J. K.; Zhu, Y.; Fu, Y. Q.; Flewitt, A. J.; Spearing, S. M.; Miao, J. M.; Milne, W. I.

    2006-04-01

    To reduce power consumption and operation temperature for micro-thermal actuators, metal-based micro-mechanical locks with multi-locking positions were analyzed and fabricated. The micro-locks consist of two or three U-shaped thermal actuators. The devices were made by a single mask process using electroplated Ni as the active material. Tests showed that the metal based thermal actuators deliver a maximum displacement of ~20µm at a much lower temperature than that of Si-based actuators. However Ni-actuators showed a severe back bending, which increases with increasing applied power. The temperature to initiate the back bending is as low as ~240°C. Back bending increases the distance between the two actuators, and leads to locking function failure. For practical application, Ni-based thermal actuators must be operated below 200°C.

  6. Mechatronics and Bioinspiration in Actuator Design and Control

    Directory of Open Access Journals (Sweden)

    J. L. Pons

    2008-01-01

    Full Text Available Actuators are components of motion control systems in which mechatronics plays a crucial role. They can be regarded as a paradigmatic case in which this mechatronic approach is required. Furthermore, actuator technologies can get new sources of inspiration from nature (bioinspiration. Biological systems are the result of an evolutionary process and show excellent levels of performance. In this paper, we analyse the actuator as a bioinspired mechatronic system through analogies between mechatronics and biological actuating mechanisms that include hierarchical control of actuators, switched control of power flow and some transduction principles. Firstly, some biological models are introduced as a source of inspiration for setting up both actuation principles and control technologies. Secondly, a particular actuator technology, the travelling wave ultrasonic motor, is taken to illustrate this approach. Eventually, the last section draws some conclusions and points out future directions.

  7. Soft Robotic Actuators

    Science.gov (United States)

    Godfrey, Juleon Taylor

    In this thesis a survey on soft robotic actuators is conducted. The actuators are classified into three main categories: Pneumatic Artificial Muscles (PAM), Electronic Electroactive Polymers (Electric EAP), and Ionic Electroactive Polymers (Ionic EAP). Soft robots can have many degrees and are more compliant than hard robots. This makes them suitable for applications that are difficult for hard robots. For each actuator background history, build materials, how they operate, and modeling are presented. Multiple actuators in each class are reviewed highlighting both their use and their mathematical formulation. In addition to the survey the McKibben actuator was chosen for fabrication and in-depth experimental analysis. Four McKibben actuators were fabricated using mesh sleeve, barbed hose fittings, and different elastic bladders. All were actuated using compressed air. Tensile tests were performed for each actuator to measure the tension force as air pressure increased from 20 to 100 psi in 10 psi increments. To account for material relaxation properties eleven trials for each actuator were run for 2-3 days. In conclusion, the smallest outer diameter elastic bladder was capable of producing the highest force due to the larger gap between the bladder and the sleeve.

  8. Electrostatically Driven Nanoballoon Actuator.

    Science.gov (United States)

    Barzegar, Hamid Reza; Yan, Aiming; Coh, Sinisa; Gracia-Espino, Eduardo; Dunn, Gabriel; Wågberg, Thomas; Louie, Steven G; Cohen, Marvin L; Zettl, Alex

    2016-11-09

    We demonstrate an inflatable nanoballoon actuator based on geometrical transitions between the inflated (cylindrical) and collapsed (flattened) forms of a carbon nanotube. In situ transmission electron microscopy experiments employing a nanoelectromechanical manipulator show that a collapsed carbon nanotube can be reinflated by electrically charging the nanotube, thus realizing an electrostatically driven nanoballoon actuator. We find that the tube actuator can be reliably cycled with only modest control voltages (few volts) with no apparent wear or fatigue. A complementary theoretical analysis identifies critical parameters for nanotube nanoballoon actuation.

  9. Magnetic suspension characteristics of electromagnetic actuators

    Science.gov (United States)

    Rao, Dantam K.; Dill, J.; Zorzi, E.

    1993-01-01

    Electromagnetic actuators that use a current-carrying coil (which is placed in a magnetic field) to generate mechanical force are conceptually attractive components for active control of rotating shafts. In one concept that is being tested in the laboratory, the control forces from such actuators are applied on the flexibly supported bearing housings of the rotor. Development of this concept into a practical reality requires a clear and thorough understanding of the role of electromechanical parameters of these actuators in delivering the right amount of control force at the right phase into the rotor. The electromechanical parameters of the actuators investigated are the mass of the armature, stiffness of its suspension, electrical resistance, and inductance of the coils. Improper selection of these parameters can result in degradation in their performance, leading to mistuning between the actuator and the rotor. Through a simple analysis, it is shown that use of such mistuned actuators could result in sharp fluctuations in the phase of the control force delivered into the rotor around the critical speeds. These sharp fluctuations in phase, called 'Phase Glitches', are undesirable. Hence, future designs of controllers should take into account the undesirable mistuning effects between the actuator and the rotor caused by the phase glitches.

  10. A Novel Tunable Multi-Frequency Hybrid Vibration Energy Harvester Using Piezoelectric and Electromagnetic Conversion Mechanisms

    Directory of Open Access Journals (Sweden)

    Zhenlong Xu

    2016-01-01

    Full Text Available This paper presents a novel tunable multi-frequency hybrid energy harvester (HEH. It consists of a piezoelectric energy harvester (PEH and an electromagnetic energy harvester (EMEH, which are coupled with magnetic interaction. An electromechanical coupling model was developed and numerically simulated. The effects of magnetic force, mass ratio, stiffness ratio, and mechanical damping ratios on the output power were investigated. A prototype was fabricated and characterized by experiments. The measured first peak power increases by 16.7% and 833.3% compared with that of the multi-frequency EMEH and the multi-frequency PEH, respectively. It is 2.36 times more than the combined output power of the linear PEH and linear EMEH at 22.6 Hz. The half-power bandwidth for the first peak power is also broadened. Numerical results agree well with the experimental data. It is indicated that magnetic interaction can tune the resonant frequencies. Both magnetic coupling configuration and hybrid conversion mechanism contribute to enhancing the output power and widening the operation bandwidth. The magnitude and direction of magnetic force have significant effects on the performance of the HEH. This proposed HEH is an effective approach to improve the generating performance of the micro-scale energy harvesting devices in low-frequency range.

  11. Thermo-Mechanical Modeling of Laser-Mig Hybrid Welding (lmhw)

    Science.gov (United States)

    Kounde, Ludovic; Engel, Thierry; Bergheau, Jean-Michel; Boisselier, Didier

    2011-01-01

    Hybrid welding is a combination of two different technologies such as laser (Nd: YAG, CO2…) and electric arc welding (MIG, MAG / TIG …) developed to assemble thick metal sheets (over 3 mm) in order to reduce the required laser power. As a matter of fact, hybrid welding is a lso used in the welding of thin materials to benefit from process, deep penetration and gap limit. But the thermo-mechanical behaviour of thin parts assembled by LMHW technology for railway cars production is far from being controlled the modeling and simulation contribute to the assessment of the causes and effects of the thermo mechanical behaviour in the assembled parts. In order to reproduce the morphology of melted and heat-affected zones, two analytic functions were combined to model the heat source of LMHW. On one hand, we applied a so-called "diaboloïd" (DB) which is a modified hyperboloid, based on experimental parameters and the analysis of the macrographs of the welds. On the other hand, we used a so-called "double ellipsoïd" (DE) which takes the MIG only contribution including the bead into account. The comparison between experimental result and numerical result shows a good agreement.

  12. Multifunctional hybrid diode: Study of photoresponse, high responsivity, and charge injection mechanisms

    Science.gov (United States)

    Singh, Jitendra; Singh, R. G.; Gautam, Subodh K.; Singh, Fouran

    2018-05-01

    A multifunctional hybrid heterojunction diode is developed on porous silicon and its current density-voltage characteristics reveal a good rectification ratio along with other superior parameters such as ideality factor, barrier height and series resistance. The diode also functions as an efficient photodiode to manifest high photosensitivity with high responsivity under illumination with broadband solar light, UV light, and green light. The diode is also carefully scrutinized for its sensitivity and repeatability over many cycles under UV and green light and is found to have a quick response and extremely fast recovery times. The notable responsivity is attributed to the generation of high density of excitons in the depletion region by the absorption of incident photons and their separation by an internal electric field besides an additional photocurrent due to the charging of polymer chains. The mechanisms of generation, injection and transport of charge carriers are explained by developing a schematic energy band diagram. The transport phenomenon of carriers is further investigated from room temperature down to a very low temperature of 10 K. An Arrhenius plot is made to determine the Richardson constant. Various diode parameters as mentioned above are also determined and the dominance of the transport mechanism of charge carriers in different temperature regimes such as diffusion across the junction and/or quantum tunneling through the barriers are explained. The developed multifunction heterojunction hybrid diodes have implications for highly sensitive photodiodes in the UV and visible range of electromagnetic spectrum that can be very promising for efficient optoelectronic devices.

  13. Mechanical Characterization and Water Absorption Behaviour of Interwoven Kenaf/PET Fibre Reinforced Epoxy Hybrid Composite

    Directory of Open Access Journals (Sweden)

    Yakubu Dan-mallam

    2015-01-01

    Full Text Available The development of interwoven fabric for composite production is a novel approach that can be adopted to address the challenges of balanced mechanical properties and water absorption behaviour of polymer composites. In this paper, kenaf and PET (polyethylene terephthalate fibre were selected as reinforcing materials to develop the woven fabric, and low viscosity epoxy resin was chosen as the matrix. Vacuum infusion process was adopted to produce the hybrid composite due to its superior advantages over hand lay-up technique. The weight percentage composition of the Epoxy/kenaf/PET hybrid composite was maintained at 70/15/15 and 60/20/20, respectively. A significant increase in tensile strength and elastic modulus of approximately 73% and 53% was recorded in relation to neat epoxy. Similarly, a substantial increase in flexural, impact, and interlaminar properties was also realized in relation to neat epoxy. This enhancement in mechanical properties may be attributed to the interlocking structure of the interwoven fabric, individual properties of kenaf and PET fibres, strong interfacial bonding, and resistance of the fibres to impact loading. The water absorption of the composites was studied by prolonged exposure in distilled water, and the moisture absorption pattern was found to follow Fickian behaviour.

  14. Mechanical Behavior of Nanostructured Hybrids Based on Poly(Vinyl Alcohol/Bioactive Glass Reinforced with Functionalized Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    H. S. Mansur

    2012-01-01

    Full Text Available This study reports the synthesis and characterization of novel tridimensional porous hybrids based on PVA combined with bioactive glass and reinforced by chemically functionalized carbon nanotubes (CNT for potential use in bone tissue engineering. The functionalization of CNT was performed by introducing carboxylic groups in multiwall nanotubes. This process aimed at enhancing the affinity of CNTs with the water-soluble PVA polymer derived by the hydrogen bonds formed among alcohol (PVA and carboxylic groups (CNT–COOH. In the sequence, the CNT–COOH (0.25 wt% were used as the nanostructure modifier for the hybrid system based on PVA associated with the bioactive glass (BaG. The mechanical properties of the nanostructured hybrids reinforced with CNT–COOH were evaluated by axial compression tests, and they were compared to reference hybrid. The averaged yield stresses of macroporous hybrids were (2.3 ± 0.9 and (4.4 ± 1.0 MPa for the reference and the CNT reinforced materials, respectively. Moreover, yield strain and Young's modulus were significantly enhanced by about 30% for the CNT–COOH hybrids. Hence, as far as the mechanical properties are concerned, the results have clearly showed the feasibility of utilizing these new hybrids reinforced with functionalized CNT in repairing cancellous bone tissues.

  15. Design and modeling of an efficiency horizontal thermal micro-actuator with integrated piezoresistors for precise control.

    Science.gov (United States)

    Zhang, Yan; Lee, Dong-Weon

    2010-05-01

    An integrated system made up of a double-hot arm electro-thermal microactuator and a piezoresistor embedded at the base of the 'cold arm' is proposed. The electro-thermo-mechanical modeling and optimization is developed to elaborate the operation mechanism of the hybrid system through numerical simulations. For given materials, the geometry design mostly influences the performance of the sensor and actuator, which can be considered separately. That is because thermal expansion induced heating energy has less influence on the base area of the 'cold arm,' where is the maximum stress. The piezoresistor is positioned here for large sensitivity to monitor the in-plane movement of the system and characterize the actuator response precisely in real time. Force method is used to analyze the thermal induced mechanical expansion in the redundant structure. On the other hand, the integrated actuating mechanism is designed for high speed imaging. Based on the simulation results, the actuator operates at levels below 5 mA appearing to be very reliable, and the stress sensitivity is about 40 MPa per micron.

  16. Relationships between the curing conditions and some mechanical properties of hybrid thermosetting materials

    International Nuclear Information System (INIS)

    Dias Filho, Newton L.; Aquino, Hermes A. de; Cardoso, Celso X.

    2006-01-01

    The relationship between the heat of polymerization (ΑH) and activation energy (E a ) parameters, obtained by differential scanning calorimetry (DSC) and the ratio of epoxy resin to hardener of the thermosetting materials based on an organic-inorganic hybrid epoxy resin (OG) was investigated. Activation energy (E a ) and heat of polymerization (ΑH) increased with an increasing OG content, up to 70 wt %. Further increase in OG content to 80 wt % reduced E a and ΑH. Dynamic mechanical analysis indicates that the maximum cross-link density is obtained at 83 wt % OG, whereas fracture toughness and tensile modulus mechanical properties are maximized at 70 wt % OG. (author)

  17. Relationships between the curing conditions and some mechanical properties of hybrid thermosetting materials

    Energy Technology Data Exchange (ETDEWEB)

    Dias Filho, Newton L.; Aquino, Hermes A. de [UNESP, Ilha Solteira, SP (Brazil). Dept. de Fisica e Quimica]. E-mail: nldias@dfq.feis.unesp.br; Cardoso, Celso X. [UNESP, Presidente Prudente, SP (Brazil). Dept. de Fisica, Quimica e Biologia

    2006-09-15

    The relationship between the heat of polymerization ({alpha}H) and activation energy (E{sub a}) parameters, obtained by differential scanning calorimetry (DSC) and the ratio of epoxy resin to hardener of the thermosetting materials based on an organic-inorganic hybrid epoxy resin (OG) was investigated. Activation energy (E{sub a}) and heat of polymerization ({alpha}H) increased with an increasing OG content, up to 70 wt %. Further increase in OG content to 80 wt % reduced E{sub a} and {alpha}H. Dynamic mechanical analysis indicates that the maximum cross-link density is obtained at 83 wt % OG, whereas fracture toughness and tensile modulus mechanical properties are maximized at 70 wt % OG. (author)

  18. Effect of reduced graphene oxide-carbon nanotubes hybrid nanofillers in mechanical properties of polymer nanocomposites

    Science.gov (United States)

    Sa, Kadambinee; Mahakul, Prakash C.; Subramanyam, B. V. R. S.; Raiguru, Jagatpati; Das, Sonali; Alam, Injamul; Mahanandia, Pitamber

    2018-03-01

    Graphene and carbon nanotubes (CNTs) have tremendous interest as reinforcing fillers due to their excellent physical properties. However, their reinforcing effect in polymer matrix is limited due to agglomeration of graphene and CNTs within the polymer matrix. Mechanical properties by the admixture of reduced graphene oxide (rGO) and CNTs in Poly (methyl methacrylate) (PMMA) prepared by solution mixing method has been investigated. The prepared samples are characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and Raman spectroscopy. The hybrid composite shows improvement in the mechanical properties compared to rGO/PMMA and MWCNTs/PMMA composites due to better interaction between rGO-MWCNTs and polymer matrix.

  19. Enhanced mechanical properties and biocompatibility of novel hydroxyapatite/TOPAS hybrid composite for bone tissue engineering applications

    Energy Technology Data Exchange (ETDEWEB)

    Ain, Qurat Ul [Department of Materials Engineering, School of Chemical and Materials Engineering, National University of Sciences and Technology, H-12, Islamabad (Pakistan); Khan, Ahmad Nawaz, E-mail: ahmad.nawaz@scme.nust.edu.pk [Department of Materials Engineering, School of Chemical and Materials Engineering, National University of Sciences and Technology, H-12, Islamabad (Pakistan); Nabavinia, Mahboubeh [Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA (United States); Mujahid, Mohammad [Department of Materials Engineering, School of Chemical and Materials Engineering, National University of Sciences and Technology, H-12, Islamabad (Pakistan)

    2017-06-01

    The bioactivity and mechanical properties of hybrid composites of hydroxyapatite (HA) in cyclic olefinic copolymer (COC) also known commercially as TOPAS are investigated, first time, for regeneration and repair of the bone tissues. HA is synthesized to obtain the spherically shaped nanoparticles in the size range of 60 ± 20 nm. Various concentrations of HA ranging from 1 to 30 wt% are dispersed in TOPAS using sodium dodecyl sulfate (SDS) coupling agent for better dispersion and interaction of hydrophilic HA with hydrophobic TOPAS. Scanning electron microscope shows the uniform dispersion of HA ≤ 10 wt% in TOPAS and at higher concentrations > 10 wt%, agglomeration occurs in the hybrid composites. Tunable mechanical properties are achieved as the compressive modulus and strength are increased around 140% from 6.4 to 15.3 MPa and 185% from 0.26 to 0.74 MPa, respectively. Such increase in the mechanical properties of TOPAS is attributed to the anchoring of the polymer chains in the vicinity of HA nanoparticles owing to better dispersion and interfacial interactions. In comparison to neat TOPAS, hybrid composites of TOPAS/HA promoted the cell adhesion and proliferation significantly. The cell density and proliferation of TOPAS/HA hybrid composites is enhanced 9 and 3 folds, respectively, after 1 day culturing in preosteoblasts cells. Moreover, the morphology of cells changed from spherical to flattened spread morphology demonstrating clearly the migration of the cells for the formation of interconnected cellular network. Additionally, very few dead cells are found in hybrid composites showing their cytocompatibility. Overall, the hybrid composites of TOPAS/HA exhibited superior strength and stiffness along with enhanced cytocompatibility for bone tissue engineering applications. - Highlights: • TOPAS/HA hybrid composites exhibited enhanced mechanical properties owing to better dispersion and interaction of HA. • Without affecting the degradation rate, the

  20. Enhanced mechanical properties and biocompatibility of novel hydroxyapatite/TOPAS hybrid composite for bone tissue engineering applications

    International Nuclear Information System (INIS)

    Ain, Qurat Ul; Khan, Ahmad Nawaz; Nabavinia, Mahboubeh; Mujahid, Mohammad

    2017-01-01

    The bioactivity and mechanical properties of hybrid composites of hydroxyapatite (HA) in cyclic olefinic copolymer (COC) also known commercially as TOPAS are investigated, first time, for regeneration and repair of the bone tissues. HA is synthesized to obtain the spherically shaped nanoparticles in the size range of 60 ± 20 nm. Various concentrations of HA ranging from 1 to 30 wt% are dispersed in TOPAS using sodium dodecyl sulfate (SDS) coupling agent for better dispersion and interaction of hydrophilic HA with hydrophobic TOPAS. Scanning electron microscope shows the uniform dispersion of HA ≤ 10 wt% in TOPAS and at higher concentrations > 10 wt%, agglomeration occurs in the hybrid composites. Tunable mechanical properties are achieved as the compressive modulus and strength are increased around 140% from 6.4 to 15.3 MPa and 185% from 0.26 to 0.74 MPa, respectively. Such increase in the mechanical properties of TOPAS is attributed to the anchoring of the polymer chains in the vicinity of HA nanoparticles owing to better dispersion and interfacial interactions. In comparison to neat TOPAS, hybrid composites of TOPAS/HA promoted the cell adhesion and proliferation significantly. The cell density and proliferation of TOPAS/HA hybrid composites is enhanced 9 and 3 folds, respectively, after 1 day culturing in preosteoblasts cells. Moreover, the morphology of cells changed from spherical to flattened spread morphology demonstrating clearly the migration of the cells for the formation of interconnected cellular network. Additionally, very few dead cells are found in hybrid composites showing their cytocompatibility. Overall, the hybrid composites of TOPAS/HA exhibited superior strength and stiffness along with enhanced cytocompatibility for bone tissue engineering applications. - Highlights: • TOPAS/HA hybrid composites exhibited enhanced mechanical properties owing to better dispersion and interaction of HA. • Without affecting the degradation rate, the

  1. Optical and mechanical excitation thermography for impact response in basalt-carbon hybrid fiber-reinforced composite laminates

    OpenAIRE

    Zhang, Hai; Sfarra, Stefano; Sarasini, Fabrizio; Ibarra-Castanedo, Clemente; Perilli, Stefano; Fernandes, Henrique; Duan, Yuxia; Peeters, Jeroen; Avelidis, Nicholas P; Maldague, Xavier

    2017-01-01

    Abstract: In this paper, optical and mechanical excitation thermography were used to investigate basalt fiber reinforced polymer (BFRP), carbon fiber reinforced polymer (CFRP) and basalt-carbon fiber hybrid specimens subjected to impact loading. Interestingly, two different hybrid structures including sandwich-like and intercalated stacking sequence were used. Pulsed phase thermography (PPT), principal component thermography (PCT) and partial least squares thermography (PLST) were used to pro...

  2. Intelligent design optimization of a shape-memory-alloy-actuated reconfigurable wing

    Science.gov (United States)

    Lagoudas, Dimitris C.; Strelec, Justin K.; Yen, John; Khan, Mohammad A.

    2000-06-01

    The unique thermal and mechanical properties offered by shape memory alloys (SMAs) present exciting possibilities in the field of aerospace engineering. When properly trained, SMA wires act as linear actuators by contracting when heated and returning to their original shape when cooled. It has been shown experimentally that the overall shape of an airfoil can be altered by activating several attached SMA wire actuators. This shape-change can effectively increase the efficiency of a wing in flight at several different flow regimes. To determine the necessary placement of these wire actuators within the wing, an optimization method that incorporates a fully-coupled structural, thermal, and aerodynamic analysis has been utilized. Due to the complexity of the fully-coupled analysis, intelligent optimization methods such as genetic algorithms have been used to efficiently converge to an optimal solution. The genetic algorithm used in this case is a hybrid version with global search and optimization capabilities augmented by the simplex method as a local search technique. For the reconfigurable wing, each chromosome represents a realizable airfoil configuration and its genes are the SMA actuators, described by their location and maximum transformation strain. The genetic algorithm has been used to optimize this design problem to maximize the lift-to-drag ratio for a reconfigured airfoil shape.

  3. An Estimation of Hybrid Quantum Mechanical Molecular Mechanical Polarization Energies for Small Molecules Using Polarizable Force-Field Approaches.

    Science.gov (United States)

    Huang, Jing; Mei, Ye; König, Gerhard; Simmonett, Andrew C; Pickard, Frank C; Wu, Qin; Wang, Lee-Ping; MacKerell, Alexander D; Brooks, Bernard R; Shao, Yihan

    2017-02-14

    In this work, we report two polarizable molecular mechanics (polMM) force field models for estimating the polarization energy in hybrid quantum mechanical molecular mechanical (QM/MM) calculations. These two models, named the potential of atomic charges (PAC) and potential of atomic dipoles (PAD), are formulated from the ab initio quantum mechanical (QM) response kernels for the prediction of the QM density response to an external molecular mechanical (MM) environment (as described by external point charges). The PAC model is similar to fluctuating charge (FQ) models because the energy depends on external electrostatic potential values at QM atomic sites; the PAD energy depends on external electrostatic field values at QM atomic sites, resembling induced dipole (ID) models. To demonstrate their uses, we apply the PAC and PAD models to 12 small molecules, which are solvated by TIP3P water. The PAC model reproduces the QM/MM polarization energy with a R 2 value of 0.71 for aniline (in 10,000 TIP3P water configurations) and 0.87 or higher for other 11 solute molecules, while the PAD model has a much better performance with R 2 values of 0.98 or higher. The PAC model reproduces reference QM/MM hydration free energies for 12 solute molecules with a RMSD of 0.59 kcal/mol. The PAD model is even more accurate, with a much smaller RMSD of 0.12 kcal/mol, with respect to the reference. This suggests that polarization effects, including both local charge distortion and intramolecular charge transfer, can be well captured by induced dipole type models with proper parametrization.

  4. Experimental Investigation on Airfoil Shock Control by Plasma Aerodynamic Actuation

    International Nuclear Information System (INIS)

    Sun Quan; Cheng Bangqin; Li Yinghong; Cui Wei; Jin Di; Li Jun

    2013-01-01

    An experimental investigation on airfoil (NACA64—215) shock control is performed by plasma aerodynamic actuation in a supersonic tunnel (Ma = 2). The results of schlieren and pressure measurement show that when plasma aerodynamic actuation is applied, the position moves forward and the intensity of shock at the head of the airfoil weakens. With the increase in actuating voltage, the total pressure measured at the head of the airfoil increases, which means that the shock intensity decreases and the control effect increases. The best actuation effect is caused by upwind-direction actuation with a magnetic field, and then downwind-direction actuation with a magnetic field, while the control effect of aerodynamic actuation without a magnetic field is the most inconspicuous. The mean intensity of the normal shock at the head of the airfoil is relatively decreased by 16.33%, and the normal shock intensity is relatively reduced by 27.5% when 1000 V actuating voltage and upwind-direction actuation are applied with a magnetic field. This paper theoretically analyzes the Joule heating effect generated by DC discharge and the Lorentz force effect caused by the magnetic field. The discharge characteristics are compared for all kinds of actuation conditions to reveal the mechanism of shock control by plasma aerodynamic actuation

  5. A hybrid online scheduling mechanism with revision and progressive techniques for autonomous Earth observation satellite

    Science.gov (United States)

    Li, Guoliang; Xing, Lining; Chen, Yingwu

    2017-11-01

    The autonomicity of self-scheduling on Earth observation satellite and the increasing scale of satellite network attract much attention from researchers in the last decades. In reality, the limited onboard computational resource presents challenge for the online scheduling algorithm. This study considered online scheduling problem for a single autonomous Earth observation satellite within satellite network environment. It especially addressed that the urgent tasks arrive stochastically during the scheduling horizon. We described the problem and proposed a hybrid online scheduling mechanism with revision and progressive techniques to solve this problem. The mechanism includes two decision policies, a when-to-schedule policy combining periodic scheduling and critical cumulative number-based event-driven rescheduling, and a how-to-schedule policy combining progressive and revision approaches to accommodate two categories of task: normal tasks and urgent tasks. Thus, we developed two heuristic (re)scheduling algorithms and compared them with other generally used techniques. Computational experiments indicated that the into-scheduling percentage of urgent tasks in the proposed mechanism is much higher than that in periodic scheduling mechanism, and the specific performance is highly dependent on some mechanism-relevant and task-relevant factors. For the online scheduling, the modified weighted shortest imaging time first and dynamic profit system benefit heuristics outperformed the others on total profit and the percentage of successfully scheduled urgent tasks.

  6. Prediction of Sliding Friction Coefficient Based on a Novel Hybrid Molecular-Mechanical Model.

    Science.gov (United States)

    Zhang, Xiaogang; Zhang, Yali; Wang, Jianmei; Sheng, Chenxing; Li, Zhixiong

    2018-08-01

    Sliding friction is a complex phenomenon which arises from the mechanical and molecular interactions of asperities when examined in a microscale. To reveal and further understand the effects of micro scaled mechanical and molecular components of friction coefficient on overall frictional behavior, a hybrid molecular-mechanical model is developed to investigate the effects of main factors, including different loads and surface roughness values, on the sliding friction coefficient in a boundary lubrication condition. Numerical modelling was conducted using a deterministic contact model and based on the molecular-mechanical theory of friction. In the contact model, with given external loads and surface topographies, the pressure distribution, real contact area, and elastic/plastic deformation of each single asperity contact were calculated. Then asperity friction coefficient was predicted by the sum of mechanical and molecular components of friction coefficient. The mechanical component was mainly determined by the contact width and elastic/plastic deformation, and the molecular component was estimated as a function of the contact area and interfacial shear stress. Numerical results were compared with experimental results and a good agreement was obtained. The model was then used to predict friction coefficients in different operating and surface conditions. Numerical results explain why applied load has a minimum effect on the friction coefficients. They also provide insight into the effect of surface roughness on the mechanical and molecular components of friction coefficients. It is revealed that the mechanical component dominates the friction coefficient when the surface roughness is large (Rq > 0.2 μm), while the friction coefficient is mainly determined by the molecular component when the surface is relatively smooth (Rq < 0.2 μm). Furthermore, optimal roughness values for minimizing the friction coefficient are recommended.

  7. Fabrication and actuation of electro-active polymer actuator based on PSMI-incorporated PVDF

    Science.gov (United States)

    Lu, Jun; Kim, Sang-Gyun; Lee, Sunwoo; Oh, Il-Kwon

    2008-08-01

    In this study, an ionic networking membrane (INM) of poly(styrene-alt-maleimide) (PSMI)-incorporated poly(vinylidene fluoride) (PVDF) was applied to fabricate electro-active polymer. Based on the same original membrane of PSMI-incorporated PVDF, various samples of INM actuator were prepared for different reduction times with the electroless-plating technique. The as-prepared INM actuators were tested in terms of surface resistance, platinum morphology, resonance frequency, tip displacement, current and blocked force, and their performances were compared to those of the widely used traditional Nafion actuator. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that much smaller and more uniform platinum particles were formed on the surfaces of the INM actuators as well as within their polymer matrix. Although excellent harmonic responses were observed for the newly developed INM actuators, they were found to be sensitive to the applied reduction times during the fabrication. The mechanical displacement of the INM actuator fabricated after the optimum reduction times was much larger than that of its Nafion counterpart of comparable thickness under the stimulus of constant and alternating current voltage. The PSMI-incorporated PVDF actuator can become a promising smart material to be used in the fields of biomimetic robots, biomedical devices, sensors and actuator, haptic interfaces, energy harvesting and so on.

  8. Fabrication and actuation of electro-active polymer actuator based on PSMI-incorporated PVDF

    International Nuclear Information System (INIS)

    Lu, Jun; Oh, Il-Kwon; Kim, Sang-Gyun; Lee, Sunwoo

    2008-01-01

    In this study, an ionic networking membrane (INM) of poly(styrene-alt-maleimide) (PSMI)-incorporated poly(vinylidene fluoride) (PVDF) was applied to fabricate electro-active polymer. Based on the same original membrane of PSMI-incorporated PVDF, various samples of INM actuator were prepared for different reduction times with the electroless-plating technique. The as-prepared INM actuators were tested in terms of surface resistance, platinum morphology, resonance frequency, tip displacement, current and blocked force, and their performances were compared to those of the widely used traditional Nafion actuator. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that much smaller and more uniform platinum particles were formed on the surfaces of the INM actuators as well as within their polymer matrix. Although excellent harmonic responses were observed for the newly developed INM actuators, they were found to be sensitive to the applied reduction times during the fabrication. The mechanical displacement of the INM actuator fabricated after the optimum reduction times was much larger than that of its Nafion counterpart of comparable thickness under the stimulus of constant and alternating current voltage. The PSMI-incorporated PVDF actuator can become a promising smart material to be used in the fields of biomimetic robots, biomedical devices, sensors and actuator, haptic interfaces, energy harvesting and so on

  9. A magnetorheological actuation system: test and model

    International Nuclear Information System (INIS)

    John, Shaju; Chaudhuri, Anirban; Wereley, Norman M

    2008-01-01

    Self-contained actuation systems, based on frequency rectification of the high frequency motion of an active material, can produce high force and stroke output. Magnetorheological (MR) fluids are active fluids whose rheological properties can be altered by the application of a magnetic field. By using MR fluids as the energy transmission medium in such hybrid devices, a valving system with no moving parts can be implemented and used to control the motion of an output cylinder shaft. The MR fluid based valves are configured in the form of an H-bridge to produce bi-directional motion in an output cylinder by alternately applying magnetic fields in the two opposite arms of the bridge. The rheological properties of the MR fluid are modeled using both Bingham plastic and bi-viscous models. In this study, the primary actuation is performed using a compact terfenol-D rod driven pump and frequency rectification of the rod motion is done using passive reed valves. The pump and reed valve configuration along with MR fluidic valves form a compact hydraulic actuation system. Actuator design, analysis and experimental results are presented in this paper. A time domain model of the actuator is developed and validated using experimental data

  10. Development of a hybrid haptic master system without using a force sensor

    International Nuclear Information System (INIS)

    Bae, Byung Hoon; Park, Kyi Hwan

    2001-01-01

    A hybrid type master system is proposed to take the advantage of the link mechanism and magnetic levitation mechanism without using a force sensor. Two different types of electromagnetic actuators, moving coil type and moving magnet types are used to drive the master system which is capable of 4-DOF actuation. It is designed that the rotation motions about x-y axis are decoupled and the whole system is represented by simple dynamic equations. The force reflection is achieved by using the simple relation between the force and applied current and position. The simulation and experimental results are presented to show its performance

  11. Development of a hybrid haptic master system without using a force sensor

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Byung Hoon; Park, Kyi Hwan [Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of)

    2001-08-01

    A hybrid type master system is proposed to take the advantage of the link mechanism and magnetic levitation mechanism without using a force sensor. Two different types of electromagnetic actuators, moving coil type and moving magnet types are used to drive the master system which is capable of 4-DOF actuation. It is designed that the rotation motions about x-y axis are decoupled and the whole system is represented by simple dynamic equations. The force reflection is achieved by using the simple relation between the force and applied current and position. The simulation and experimental results are presented to show its performance.

  12. Sensors and actuators inherent in biological species

    Science.gov (United States)

    Taya, Minoru; Stahlberg, Rainer; Li, Fanghong; Zhao, Ying Joyce

    2007-04-01

    This paper addresses examples of sensing and active mechanisms inherent in some biological species where both plants and animals cases are discussed: mechanosensors and actuators in Venus Fly Trap and cucumber tendrils, chemosensors in insects, two cases of interactions between different kingdoms, (i) cotton plant smart defense system and (ii) bird-of-paradise flower and hamming bird interaction. All these cases lead us to recognize how energy-efficient and flexible the biological sensors and actuators are. This review reveals the importance of integration of sensing and actuation functions into an autonomous system if we make biomimetic design of a set of new autonomous systems which can sense and actuate under a number of different stimuli and threats.

  13. Fast electrochemical actuator

    International Nuclear Information System (INIS)

    Uvarov, I V; Postnikov, A V; Svetovoy, V B

    2016-01-01

    Lack of fast and strong microactuators is a well-recognized problem in MEMS community. Electrochemical actuators can develop high pressure but they are notoriously slow. Water electrolysis produced by short voltage pulses of alternating polarity can overcome the problem of slow gas termination. Here we demonstrate an actuation regime, for which the gas pressure is relaxed just for 10 μs or so. The actuator consists of a microchamber filled with the electrolyte and covered with a flexible membrane. The membrane bends outward when the pressure in the chamber increases. Fast termination of gas and high pressure developed in the chamber are related to a high density of nanobubbles in the chamber. The physical processes happening in the chamber are discussed so as problems that have to be resolved for practical applications of this actuation regime. The actuator can be used as a driving engine for microfluidics. (paper)

  14. Recent Progress on Cellulose-Based Electro-Active Paper, Its Hybrid Nanocomposites and Applications.

    Science.gov (United States)

    Khan, Asif; Abas, Zafar; Kim, Heung Soo; Kim, Jaehwan

    2016-07-26

    We report on the recent progress and development of research into cellulose-based electro-active paper for bending actuators, bioelectronics devices, and electromechanical transducers. The cellulose electro-active paper is characterized in terms of its biodegradability, chirality, ample chemically modifying capacity, light weight, actuation capability, and ability to form hybrid nanocomposites. The mechanical, electrical, and chemical characterizations of the cellulose-based electro-active paper and its hybrid composites such as blends or coatings with synthetic polymers, biopolymers, carbon nanotubes, chitosan, and metal oxides, are explained. In addition, the integration of cellulose electro-active paper is highlighted to form various functional devices including but not limited to bending actuators, flexible speaker, strain sensors, energy harvesting transducers, biosensors, chemical sensors and transistors for electronic applications. The frontiers in cellulose paper devices are reviewed together with the strategies and perspectives of cellulose electro-active paper and cellulose nanocomposite research and applications.

  15. Recent Progress on Cellulose-Based Electro-Active Paper, Its Hybrid Nanocomposites and Applications

    Directory of Open Access Journals (Sweden)

    Asif Khan

    2016-07-01

    Full Text Available We report on the recent progress and development of research into cellulose-based electro-active paper for bending actuators, bioelectronics devices, and electromechanical transducers. The cellulose electro-active paper is characterized in terms of its biodegradability, chirality, ample chemically modifying capacity, light weight, actuation capability, and ability to form hybrid nanocomposites. The mechanical, electrical, and chemical characterizations of the cellulose-based electro-active paper and its hybrid composites such as blends or coatings with synthetic polymers, biopolymers, carbon nanotubes, chitosan, and metal oxides, are explained. In addition, the integration of cellulose electro-active paper is highlighted to form various functional devices including but not limited to bending actuators, flexible speaker, strain sensors, energy harvesting transducers, biosensors, chemical sensors and transistors for electronic applications. The frontiers in cellulose paper devices are reviewed together with the strategies and perspectives of cellulose electro-active paper and cellulose nanocomposite research and applications.

  16. Synthesis and Mechanical Properties Investigation of Nano TiO2/Glass/Epoxy Hybrid Nanocomposite

    Directory of Open Access Journals (Sweden)

    Hamid Reza Salehi

    2015-10-01

    Full Text Available Mechanical properties of epoxy and glass/epoxy filled with 0.25, 0.5 and 1 vol% of TiO2 nanoparticles have been studied using tensile and three-point bending tests. For the TiO2/epoxy nanocomposites, the results showed that the strength and stiffness were improved, though the strain at ultimate strength point and breaking strain decreased. Moreover, the hybrid nanocomposites composed of 4 layers of woven E-glass fabric and TiO2/epoxy matrix were fabricated and cut onaxis and 45° off-axis by water jet. The results of tensile and three-point bending tests indicated a remarkable improvement in the strength and stiffness that could not be related to the mechanical improvement of the matrix. The samples containing 1 vol% nano TiO2 were improved relative to samples without the nanoparticles. The tensile strength of the on-axis and off-axis samples containing 1 vol% TiO2 increased by about 25.9% and 17.9%, in the order given, compared to that of the glass/epoxy specimens. In three-point bending test, the strength of the on-axis and off-axis specimens was improved 26% and 23.2%, respectively. In addition, the tensile stiffness of the onaxis and off-axis samples containing 1 vol% TiO2 increased, respectively, by about 14.4% and 17.5% compared to that of the glass/epoxy specimens. Also for the same on-axis and off-axis samples the three-point bending stiffness increased about 19.8% and 14.6%, respectively. The whole investigation on the microstructure of the hybrid nanocomposites illustrated that stronger interfaces between the fiber and TiO2/epoxy matrix were formed and improvement was noticed on mechanical properties of ternary composite compared to those of the fiber/epoxy composites. The analysis of damage zones of hybrid nanocomposites showed that the surface area of the damaged zone declined considerably due to the brittle behavior of TiO2-filled specimens but the area below the stress-strain curve, showing energy absorption during the test

  17. Investigation of mechanical properties of hemp/glass fiber reinforced nano clay hybrid composites

    Science.gov (United States)

    Unki, Hanamantappa Ningappa; Shivanand, H. K.; Vidyasagar, H. N.

    2018-04-01

    Over the last twenty to thirty years composite materials have been used in engineering field. Composite materials possess high strength, high strength to weight ratio due to these facts composite materials are becoming popular among researchers and scientists. The major proportion of engineering materials consists of composite materials. Composite materials are used in vast applications ranging from day-to-day household articles to highly sophisticated applications. In this paper an attempt is made to prepare three different composite materials using e-glass and Hemp. In this present investigation hybrid composite of Hemp, Glass fiber and Nano clay will be prepared by Hand-layup technique. The glass fiber used in this present investigation is E-glass fiber bi-directional: 90˚ orientation. The composite samples will be made in the form of a Laminates. The wt% of nanoclay added in the preparation of sample is 20 gm constant. The fabricated composite Laminate will be cut into corresponding profiles as per ASTM standards for Mechanical Testing. The effect of addition of Nano clay and variation of Hemp/glass fibers will be studied. In the present work, a new Hybrid composite is developed in which Hemp, E glass fibers is reinforced with epoxy resin and with Nano clay.

  18. Further Theoretical Insight into the Mechanical Properties of Polycaprolactone Loaded with Organic–Inorganic Hybrid Fillers

    Directory of Open Access Journals (Sweden)

    Saverio Maietta

    2018-02-01

    Full Text Available Experimental/theoretical analyses have already been performed on poly(ε-caprolactone (PCL loaded with organic–inorganic fillers (PCL/TiO2 and PCL/ZrO2 to find a correlation between the results from the small punch test and Young’s modulus of the materials. PCL loaded with Ti2 (PCL = 12, TiO2 = 88 wt % and Zr2 (PCL = 12, ZrO2 = 88 wt % hybrid fillers showed better performances than those obtained for the other particle composition. In this context, the aim of current research is to provide further insight into the mechanical properties of PCL loaded with sol–gel-synthesized organic–inorganic hybrid fillers for bone tissue engineering. For this reason, theoretical analyses were performed by the finite element method. The results from the small punch test and Young’s modulus of the materials were newly correlated. The obtained values of Young’s modulus (193 MPa for PCL, 378 MPa for PCL/Ti2 and 415 MPa for PCL/Zr2 were higher than those obtained from a previous theoretical modelling (144 MPa for PCL, 282 MPa for PCL/Ti2 and 310 MPa for PCL/Zr2. This correlation will be an important step for the evaluation of Young’s modulus, starting from the small punch test data.

  19. Physical mechanism of parametric instabilities near the lower-hybrid frequency in inhomogeneous plasma

    International Nuclear Information System (INIS)

    Porkolab, M.

    1974-10-01

    The dispersion relation for parametric instabilities near the lower-hybrid frequency is obtained from model fluid equations. The following instabilities are discussed: for rf pump frequencies ω 0 greater than or equal to 3ω/sub LH/, ω/sub pe/ approximately equal to Ω/sub e/, resonant decay into ion sound (ion cyclotron) modes (previously predicted) is found. In the regime of 1 less than or equal to ω 0 /ω/sub LH/ less than or equal to 3, ω/sub pe/ approximately equal to Ω/sub e/, decay into ion quasi-modes is found. In strong magnetic fields decay into quasi-modes is also found for 3 less than or equal to ω 0 /ω/sub LH/. This mechanism is similar to nonlinear Landau damping in weak turbulence theory. In addition, decay into the purely growing mode and fluid-quasi modes may also occur. The results are compared with recent calculations from the Vlasov equation. The effects of plasma-inhomogeneities are considered, including effective thresholds due to density gradients and finite pump extent. The implications of these results to rf heating of tokamaks near the lower-hybrid frequency are discussed. (auth)

  20. Hybrid mask for deep etching

    KAUST Repository

    Ghoneim, Mohamed T.

    2017-01-01

    Deep reactive ion etching is essential for creating high aspect ratio micro-structures for microelectromechanical systems, sensors and actuators, and emerging flexible electronics. A novel hybrid dual soft/hard mask bilayer may be deposited during

  1. Mechanical properties of banana/kenaf fiber-reinforced hybrid polyester composites: Effect of woven fabric and random orientation

    International Nuclear Information System (INIS)

    Alavudeen, A.; Rajini, N.; Karthikeyan, S.; Thiruchitrambalam, M.; Venkateshwaren, N.

    2015-01-01

    Highlights: • This paper is presents the fabrications of kenaf/banana fiber hybrid composites. • Effect of weaving pattern and random orientation on mechanical properties was studied. • Role of interfacial adhesion due to chemical modifications were analyzed with the aid of SEM. • Hybridization of kenaf and banana fibers in plain woven composites exhibits maximum mechanical strength. - Abstract: The present work deals with the effect of weaving patterns and random orientatation on the mechanical properties of banana, kenaf and banana/kenaf fiber-reinforced hybrid polyester composites. Composites were prepared using the hand lay-up method with two different weaving patterns, namely, plain and twill type. Of the two weaving patterns, the plain type showed improved tensile properties compared to the twill type in all the fabricated composites. Furthermore, the maximum increase in mechanical strength was observed in the plain woven hybrid composites rather than in randomly oriented composites. This indicates minimum stress development at the interface of composites due to the distribution of load transfer along the fiber direction. Moreover, alkali (NaOH) and sodium lauryl sulfate (SLS) treatments appear to provide an additional improvement in mechanical strength through enhanced interfacial bonding. Morphological studies of fractured mechanical testing samples were performed by scanning electron microscopy (SEM) to understand the de-bonding of fiber/matrix adhesion

  2. Fpga-based control of piezoelectric actuators

    Directory of Open Access Journals (Sweden)

    Juhász László

    2011-01-01

    Full Text Available In many industrial applications like semiconductor production and optical inspection systems, the availability of positioning systems capable to follow trajectory paths in the range of several centimetres, featuring at the same time a nanometre-range precision, is demanding. Pure piezoelectric stages and standard positioning systems with motor and spindle are not able to meet such requirements, because of the small operation range and inadequacies like backlash and friction. One concept for overcoming these problems consists of a hybrid positioning system built through the integration of a DC-drive in series with a piezoelectric actuator. The wide range of potential applications enables a considerable market potential for such an actuator, but due to the high variety of possible positioned objects and dynamic requirements, the required control complexity may be significant. In this paper, a real-time capable state-space control concept for the piezoelectric actuators, embedded in such a hybrid micropositioning system, is presented. The implementation of the controller together with a real-time capable hysteresis compensation measure is performed using a low-budget FPGA-board, whereas the superimposed integrated controller is realized with a dSPACE RCP-system. The advantages of the designed control over a traditional proportional-integral control structure are proven through experimental results using a commercially available hybrid micropositioning system. Positioning results by different dynamic requirements featuring positioning velocities from 1 μm/s up to 5 cm/s are given.

  3. Effect of fibre orientations on the mechanical properties of kenaf–aramid hybrid composites for spall-liner application

    Institute of Scientific and Technical Information of China (English)

    R. YAHAYA; S.M. SAPUAN; M. JAWAID; Z. LEMAN; E.S. ZAINUDIN

    2016-01-01

    This paper presents the effect of kenaf fibre orientation on the mechanical properties of kenaf–aramid hybrid composites for military vehicle's spall liner application. It was observed that the tensile strength of woven kenaf hybrid composite is almost 20.78%and 43.55%higher than that of UD and mat samples respectively. Charpy impact strength of woven kenaf composites is 19.78%and 52.07%higher than that of UD and mat kenaf hybrid composites respectively. Morphological examinations were carried out using scanning electron microscopy. The results of this study indicate that using kenaf in the form of woven structure could produce a hybrid composite material with high tensile strength and impact resistance properties.

  4. The development and mechanical characterization of aluminium copper-carbon fiber metal matrix hybrid composite

    Science.gov (United States)

    Manzoor, M. U.; Feroze, M.; Ahmad, T.; Kamran, M.; Butt, M. T. Z.

    2018-04-01

    Metal matrix composites (MMCs) come under advanced materials that can be used for a wide range of industrial applications. MMCs contain a non-metallic reinforcement incorporated into a metallic matrix which can enhance properties over base metal alloys. Copper-Carbon fiber reinforced aluminium based hybrid composites were prepared by compo casting method. 4 weight % copper was used as alloying element with Al because of its precipitation hardened properties. Different weight compositions of composites were developed and characterized by mechanical testing. A significant improvement in tensile strength and micro hardness were found, before and after heat treatment of the composite. The SEM analysis of the fractured surfaces showed dispersed and embedded Carbon fibers within the network leading to the enhanced strength.

  5. Reactive powder based concretes: Mechanical properties, durability and hybrid use with OPC

    International Nuclear Information System (INIS)

    Cwirzen, A.; Penttala, V.; Vornanen, C.

    2008-01-01

    The basic mechanical properties, frost durability and the bond strength with normal strength concretes of the ultra high strength (UHS) mortars and concretes were studied. The produced mixes had plastic or fluid-like consistency. The 28-day compressive strength varied between 170 and 202 MPa for the heat-treated specimens and between 130 and 150 MPa for the non-heat-treated specimens. The shrinkage values were two times higher for the UHS mortars in comparison with the UHS concretes. After the initial shrinkage, swelling was noticed in the UHS mortars. The lowest creep values were measured for the non-heat-treated UHS concretes. The frost-deicing salts durability of the UHS mortars and concretes appeared to be very good even despite the increased water uptake of the UHS concretes. The study of the hybrid concrete beams indicated the formation of low strength transition zone between the UHS mortar and normal strength concrete

  6. Advanced hybrid query tree algorithm based on slotted backoff mechanism in RFID

    Directory of Open Access Journals (Sweden)

    XIE Xiaohui

    2013-12-01

    Full Text Available The merits of performance quality for a RFID system are determined by the effectiveness of tag anti-collision algorithm.Many algorithms for RFID system of tag identification have been proposed,but they all have obvious weaknesses,such as slow speed of identification,unstable and so on.The existing algorithms can be divided into two groups,one is based on ALOHA and another is based on query tree.This article is based on the hybrid query tree algorithm,combined with a slotted backoff mechanism and a specific encoding (Manchester encoding.The number of value“1” in every three consecutive bits of tags is used to determine the tag response time slots,which will greatly reduce the time slot of the collision and improve the recognition efficiency.

  7. MECHANICAL PROPERTIES OF CR-DLC LAYERS PREPARED BY HYBRID LASER TECHNOLOGY

    Directory of Open Access Journals (Sweden)

    Petr Písařík

    2017-06-01

    Full Text Available Diamond like carbon (DLC layers have excellent biological properties for use in medicine for coating implants, but poor adhesion to biomedical alloys. The adhesion can be improved by doping the DLC layer by chromium, as described in this article. Chromium doped diamond like carbon layers (Cr‑DLC were deposited by hybrid deposition system using KrF excimer laser and magnetron sputtering. Carbon and chromium contents were determined by wavelength dispersive X-ray spectroscopy. Mechanical properties were studied by nanoindentation. Hardness and reduced Young's modulus reached 31.2 GPa and 271.5 GPa, respectively. Films adhesion was determined by scratch test and reached 19 N for titanium substrates. Good adhesion to biomedical alloys and high DLC hardness will help to progress in the field of implantology.

  8. Satellite Fault Diagnosis Using Support Vector Machines Based on a Hybrid Voting Mechanism

    Science.gov (United States)

    Yang, Shuqiang; Zhu, Xiaoqian; Jin, Songchang; Wang, Xiang

    2014-01-01

    The satellite fault diagnosis has an important role in enhancing the safety, reliability, and availability of the satellite system. However, the problem of enormous parameters and multiple faults makes a challenge to the satellite fault diagnosis. The interactions between parameters and misclassifications from multiple faults will increase the false alarm rate and the false negative rate. On the other hand, for each satellite fault, there is not enough fault data for training. To most of the classification algorithms, it will degrade the performance of model. In this paper, we proposed an improving SVM based on a hybrid voting mechanism (HVM-SVM) to deal with the problem of enormous parameters, multiple faults, and small samples. Many experimental results show that the accuracy of fault diagnosis using HVM-SVM is improved. PMID:25215324

  9. Satellite Fault Diagnosis Using Support Vector Machines Based on a Hybrid Voting Mechanism

    Directory of Open Access Journals (Sweden)

    Hong Yin

    2014-01-01

    Full Text Available The satellite fault diagnosis has an important role in enhancing the safety, reliability, and availability of the satellite system. However, the problem of enormous parameters and multiple faults makes a challenge to the satellite fault diagnosis. The interactions between parameters and misclassifications from multiple faults will increase the false alarm rate and the false negative rate. On the other hand, for each satellite fault, there is not enough fault data for training. To most of the classification algorithms, it will degrade the performance of model. In this paper, we proposed an improving SVM based on a hybrid voting mechanism (HVM-SVM to deal with the problem of enormous parameters, multiple faults, and small samples. Many experimental results show that the accuracy of fault diagnosis using HVM-SVM is improved.

  10. Osmotic actuation for microfluidic components in point-of-care applications

    KAUST Repository

    Chen, Yu-Chih; Ingram, Patrick; Lou, Xia; Yoon, Euisik

    2013-01-01

    at low cost. In this work, we report two key active components actuated by osmotic mechanism for total integrated microfluidic system. For the proof of concept, we have demonstrated valve actuation, which can maintain stable ON/OFF switching operations

  11. The effects of additives on the actuating performances of a dielectric elastomer actuator

    International Nuclear Information System (INIS)

    Nguyen, Huu Chuc; Doan, Vu Thuy; Park, JongKil; Koo, Ja Choon; Choi, Hyouk Ryeol; Lee, Youngkwan; Nam, Jae-do

    2009-01-01

    This paper presents a comprehensive study of the effects of additives on the performance of a dielectric elastomer actuator. Previously, a new dielectric elastomer material, called 'synthetic elastomer', was presented for the means of actuation, which permits changes in the mechanical as well as the electrical properties in order to meet the requirements of certain applications. This work studies how the electromechanical properties of the synthetic elastomer can be adjusted by combining two additives, namely dioctyl phthalate (DOP) and titanium dioxide (TiO 2 ). Experiments are carried out and the effects of each additive are compared to one another based on the actuation performances

  12. Development of Biodegradable Poly(citrate)-Polyhedral Oligomeric Silsesquioxanes Hybrid Elastomers with High Mechanical Properties and Osteogenic Differentiation Activity.

    Science.gov (United States)

    Du, Yuzhang; Yu, Meng; Chen, Xiaofeng; Ma, Peter X; Lei, Bo

    2016-02-10

    Biodegradable elastomeric biomaterials have attracted much attention in tissue engineering due to their biomimetic viscoelastic behavior and biocompatibility. However, the low mechanical stability at hydrated state, fast biodegradation in vivo, and poor osteogenic activity greatly limited bioelastomers applications in bone tissue regeneration. Herein, we develop a series of poly(octanediol citrate)-polyhedral oligomeric silsesquioxanes (POC-POSS) hybrids with highly tunable elastomeric behavior (hydrated state) and biodegradation and osteoblasts biocompatibility through a facile one-pot thermal polymerization strategy. POC-POSS hybrids show significantly improved stiffness and ductility in either dry or hydrated conditions, as well as good antibiodegradation ability (20-50% weight loss in 3 months). POC-POSS hybrids exhibit significantly enhanced osteogenic differentiation through upregulating alkaline phosphatase (ALP) activity, calcium deposition, and expression of osteogenic markers (ALPL, BGLAP, and Runx2). The high mechanical stability at hydrated state and enhanced osteogenic activity make POC-POSS hybrid elastomers promising as scaffolds and nanoscale vehicles for bone tissue regeneration and drug delivery. This study may also provide a new strategy (controlling the stiffness under hydrated condition) to design advanced hybrid biomaterials with high mechanical properties under physiological condition for tissue regeneration applications.

  13. Effect of Environmental Degradation on Mechanical Properties of Kenaf/Polyethylene Terephthalate Fiber Reinforced Polyoxymethylene Hybrid Composite

    Directory of Open Access Journals (Sweden)

    Mohamad Zaki Abdullah

    2013-01-01

    Full Text Available The main objective of this research is to investigate the effect of environmental degradation on the mechanical properties of kenaf/PET fiber reinforced POM hybrid composite. Kenaf and PET fibers were selected as reinforcements because of their good mechanical properties and resistance to photodegradation. The test samples were produced by compression molding. The samples were exposed to moisture, water spray, and ultraviolet penetration in an accelerated weathering chamber for 672 hours. The tensile strength of the long fiber POM/kenaf (80/20 composite dropped by 50% from 127.8 to 64.8 MPa while that of the hybrid composite dropped by only 2% from 73.8 to 72.5 MPa. This suggests that the hybrid composite had higher resistance to tensile strength than the POM/kenaf composite. Similarly, the results of flexural and impact strengths also revealed that the hybrid composite showed less degradation compared to the kenaf fiber composite. The results of the investigation revealed that the hybrid composite had better retention of mechanical properties than that of the kenaf fiber composites and may be suitable for outdoor application in the automotive industry.

  14. Microstructural, mechanical, and thermal characteristics of recycled cellulose fiber-halloysite-epoxy hybrid nanocomposites

    KAUST Repository

    Alamri, H.

    2012-02-26

    Epoxy hybrid-nanocomposites reinforced with recycled cellulose fibers (RCF) and halloysite nanotubes (HNTs) have been fabricated and investigated. The dispersion of HNTs was studied by synchrotron radiation diffraction (SRD) and transmission electron microscopy (TEM). The influences of RCF/HNTs dispersion on the mechanical properties and thermal properties of these composites have been characterized in terms of flexural strength, flexural modulus, fracture toughness, impact toughness, impact strength, and thermogravimetric analysis. The fracture surface morphology and toughness mechanisms were investigated by SEM. Results indicated that mechanical properties increased because of the addition of HNTs into the epoxy matrix. Flexural strength, flexural modulus, fracture toughness, and impact toughness increased by 20.8, 72.8, 56.5, and 25.0%, respectively, at 1 wt% HNTs load. The presence of RCF dramatically enhanced flexural strength, fracture toughness, impact strength, and impact toughness of the composites by 160%, 350%, 444%, and 263%, respectively. However, adding HNTs to RCF/epoxy showed only slight enhancements in flexural strength and fracture toughness. The inclusion of 5 wt% HNTs into RCF/epoxy ecocomposites increased the impact toughness by 27.6%. The presence of either HNTs or RCF accelerated the thermal degradation of neat epoxy. However, at high temperature, samples reinforced with RCF and HNTs displayed better thermal stability with increased char residue than neat resin. © 2012 Society of Plastics Engineers.

  15. Thermal and Mechanical Behavior of Hybrid Polymer Nanocomposite Reinforced with Graphene Nanoplatelets

    Directory of Open Access Journals (Sweden)

    Minh-Tai Le

    2015-08-01

    Full Text Available In the present investigation, we successfully fabricate a hybrid polymer nanocomposite containing epoxy/polyester blend resin and graphene nanoplatelets (GNPs by a novel technique. A high intensity ultrasonicator is used to obtain a homogeneous mixture of epoxy/polyester resin and graphene nanoplatelets. This mixture is then mixed with a hardener using a high-speed mechanical stirrer. The trapped air and reaction volatiles are removed from the mixture using high vacuum. The hot press casting method is used to make the nanocomposite specimens. Tensile tests, dynamic mechanical analysis (DMA and thermogravimetric analysis (TGA are performed on neat, 0.2 wt %, 0.5 wt %, 1 wt %, 1.5 wt % and 2 wt % GNP-reinforced epoxy/polyester blend resin to investigate the reinforcement effect on the thermal and mechanical properties of the nanocomposites. The results of this research indicate that the tensile strength of the novel nanocomposite material increases to 86.8% with the addition of a ratio of graphene nanoplatelets as low as 0.2 wt %. DMA results indicate that the 1 wt % GNP-reinforced epoxy/polyester nanocomposite possesses the highest storage modulus and glass transition temperature (Tg, as compared to neat epoxy/polyester or the other nanocomposite specimens. In addition, TGA results verify thethermal stability of the experimental specimens, regardless of the weight percentage of GNPs.

  16. Optimization of the transport and mechanical properties of polysiloxane/polyether hybrid polymer electrolytes

    International Nuclear Information System (INIS)

    Boaretto, Nicola; Horn, Theresa; Popall, Michael; Sextl, Gerhard

    2017-01-01

    In this study, the thermo-mechanical properties of networked, polysiloxane/polyether-based, hybrid polymer electrolytes are optimized with the aim of enabling room-temperature operation in lithium metal-polymer batteries. The structural parameters of the electrolytes (polyether chain length, cross-linking and salt concentration) are varied in order to get the best tradeoff between conductivity and mechanical stability. The optimized material has a conductivity close to 1.5·10 −4 S cm −1 at room temperature and a shear storage modulus of 50 kPa up to 100 °C. The effect of TiO 2 nano-particles is also studied with the results showing an overall ambiguous effect on the materials properties. Finally, one of the materials with the highest conductivity is used as electrolyte in a Li/LiFePO 4 cell. This cell has good rate capability and cyclability due to the high conductivity of the electrolyte. However, the high conductivity is reached at expense of the mechanical stability and the resulting electrolyte proves to be too weak to work as an efficient barrier against lithium dendrite growth.

  17. Thermal and Mechanical Behavior of Hybrid Polymer Nanocomposite Reinforced with Graphene Nanoplatelets

    Science.gov (United States)

    Le, Minh-Tai; Huang, Shyh-Chour

    2015-01-01

    In the present investigation, we successfully fabricate a hybrid polymer nanocomposite containing epoxy/polyester blend resin and graphene nanoplatelets (GNPs) by a novel technique. A high intensity ultrasonicator is used to obtain a homogeneous mixture of epoxy/polyester resin and graphene nanoplatelets. This mixture is then mixed with a hardener using a high-speed mechanical stirrer. The trapped air and reaction volatiles are removed from the mixture using high vacuum. The hot press casting method is used to make the nanocomposite specimens. Tensile tests, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) are performed on neat, 0.2 wt %, 0.5 wt %, 1 wt %, 1.5 wt % and 2 wt % GNP-reinforced epoxy/polyester blend resin to investigate the reinforcement effect on the thermal and mechanical properties of the nanocomposites. The results of this research indicate that the tensile strength of the novel nanocomposite material increases to 86.8% with the addition of a ratio of graphene nanoplatelets as low as 0.2 wt %. DMA results indicate that the 1 wt % GNP-reinforced epoxy/polyester nanocomposite possesses the highest storage modulus and glass transition temperature (Tg), as compared to neat epoxy/polyester or the other nanocomposite specimens. In addition, TGA results verify thethermal stability of the experimental specimens, regardless of the weight percentage of GNPs. PMID:28793521

  18. Effect of Short Fiber Reinforcement on Mechanical Properties of Hybrid Phenolic Composites

    Directory of Open Access Journals (Sweden)

    Sembian Manoharan

    2014-01-01

    Full Text Available Fiber plays an important role in determining the hardness, strength, and dynamic mechanical properties of composite material. In the present work, enhancement of viscoelastic behaviour of hybrid phenolic composites has been synergistically investigated. Five different phenolic composites, namely, C1, C2, C3, C4, and C5, were fabricated by varying the weight percentage of basalt and aramid fiber, namely, 25, 20, 15, 10, and 5% by compensating with barium sulphate (BaSO4 to keep the combined reinforcement concentration at 25 wt%. Hardness was measured to examine the resistance of composites to indentation. The hardness of phenolic composites increased from 72.2 to 85.2 with increase in basalt fiber loading. Composite C1 (25 wt% fiber is 1.2 times harder than composite C5. Compression test was conducted to find out compressive strength of phenolic composites and compressive strength increased with increase in fiber content. Dynamic mechanical analysis (DMA was carried out to assess the temperature dependence mechanical properties in terms of storage modulus (E′, loss modulus (E′′, and damping factor (tan δ. The results indicate great improvement of E′ values and decrease in damping behaviour of composite upon fiber addition. Further X-ray powder diffraction (XRD and energy-dispersive X-ray (EDX analysis were employed to characterize the friction composites.

  19. Student Interactions with Online Videos in a Large Hybrid Mechanics of Materials Course

    Science.gov (United States)

    Ahn, Benjamin; Bir, Devayan D.

    2018-01-01

    The hybrid course format has gained popularity in the engineering education community over the past few years. Although studies have examined student outcomes and attitudes toward hybrid courses, a limited number of studies have examined how students interact with online videos in hybrid courses. This study examined the video-viewing behaviors of…

  20. Mild hybrids with CVT: comparison of electrical and mechanical torque assist

    NARCIS (Netherlands)

    Druten, van R.M.; Serrarens, A.F.A.; Vroemen, B.G.; Tillaart, van den E.L.; de Haas, J.

    2001-01-01

    This paper evaluates two mild hybrid drive trains for a mid-class passenger car with a gasoline engine by means of comptuer simulation. The term mild hybrid is used for vehicles with sustained electric propulsion. The mild hybrid drive trains both have a Continuously Variable Transmission (CVT) with

  1. Coupled Electro-Magneto-Mechanical-Acoustic Analysis Method Developed by Using 2D Finite Element Method for Flat Panel Speaker Driven by Magnetostrictive-Material-Based Actuator

    Science.gov (United States)

    Yoo, Byungjin; Hirata, Katsuhiro; Oonishi, Atsurou

    In this study, a coupled analysis method for flat panel speakers driven by giant magnetostrictive material (GMM) based actuator was developed. The sound field produced by a flat panel speaker that is driven by a GMM actuator depends on the vibration of the flat panel, this vibration is a result of magnetostriction property of the GMM. In this case, to predict the sound pressure level (SPL) in the audio-frequency range, it is necessary to take into account not only the magnetostriction property of the GMM but also the effect of eddy current and the vibration characteristics of the actuator and the flat panel. In this paper, a coupled electromagnetic-structural-acoustic analysis method is presented; this method was developed by using the finite element method (FEM). This analysis method is used to predict the performance of a flat panel speaker in the audio-frequency range. The validity of the analysis method is verified by comparing with the measurement results of a prototype speaker.

  2. Performance evaluation of an improved fish robot actuated by piezoceramic actuators

    Science.gov (United States)

    Nguyen, Q. S.; Heo, S.; Park, H. C.; Byun, D.

    2010-03-01

    This paper presents an improved fish robot actuated by four lightweight piezocomposite actuators. Our newly developed actuation mechanism is simple to fabricate because it works without gears. With the new actuation mechanism, the fish robot has a 30% smaller cross section than our previous model. Performance tests of the fish robot in water were carried out to measure the tail-beat angle, the thrust force, the swimming speed for various tail-beat frequencies from 1 to 5 Hz and the turning radius at the optimal frequency. The maximum swimming speed of the fish robot is 7.7 cm s - 1 at a tail-beat frequency of 3.9 Hz. A turning experiment shows that the swimming direction of the fish robot can be controlled by changing the duty ratio of the driving voltage; the fish robot has a turning radius of 0.41 m for a left turn and 0.68 m for a right turn.

  3. LEAD-FREE BNKT PIEZOELECTRIC ACTUATOR

    Directory of Open Access Journals (Sweden)

    A. Moosavi

    2016-03-01

    Full Text Available An actuator is a device that converts input energy into mechanical energy. According to various types of input energy, various actuators have been advanced. Displacement in the electromagnetic, hydraulic and pneumatic actuators achieve by moving a piston via electromagnetic force or pressure, however the piezoelectric actuator (piezoceramic plates displace directly. Therefore, accuracy and speed in the piezoelectric device are higher than other types of actuators. In the present work, the high-field electromechanical response of high-quality (1−x(Bi 0.5Na0.5TiO3–x(Bi0.5K0.5TiO3 samples abbreviated to BNKTx with x = 0.18, 0.20, 0.22 and 0.24 ceramic materials across its MPB was investigated. The piezoelectrics and actuation characteristics were characterized. Ourresults indicate that x = 0.20, indeed, constitutes the best choice for the MPB composition in the system. Maximum of remanent polarization (37.5 μC cm−2 was obtained for x=0.20. High-field electromechanical responses were also obtained for BNKT0.20 samples. This material exhibited giant field induced strains of 0.13% under 1 kV mm -1 at room temperature.

  4. Mechanical Properties of SiC, Al2O3 Reinforced Aluminium 6061-T6 Hybrid Matrix Composite

    Science.gov (United States)

    Murugan, S. Senthil; Jegan, V.; Velmurugan, M.

    2018-04-01

    This paper contains the investigation of tensile, compression and impact characterization of SiC, Al2O3 reinforced Aluminium 6061-T6 matrix hybrid composite. Hybrid matrix composite fabrication was done by stir casting method. An attempt has been made by keeping Al2O3 percentage (7%) constant and increasing SiC percentage (10, 15, and 20%). After fabricating, the samples were prepared and tested to find out the various mechanical properties like tensile, compressive, and impact strength of the developed composites of different weight % of silicon carbide and Alumina in Aluminium alloy. The main objective of the study is to compare the values obtained and choose the best composition of the hybrid matrix composite from the mechanical properties point of view.

  5. Analysis of the mechanical and thermal properties of jute and glass fiber as reinforcement epoxy hybrid composites.

    Science.gov (United States)

    Braga, R A; Magalhaes, P A A

    2015-11-01

    This work describes the study to investigate and compare the mechanical and thermal properties of raw jute and glass fiber reinforced epoxy hybrid composites. To improve the mechanical properties, jute fiber was hybridized with glass fiber. Epoxy resin, jute and glass fibers were laminated in three weight ratios (69/31/0, 68/25/7 and 64/18/19) respectively to form composites. The tensile, flexural, impact, density, thermal and water absorption tests were carried out using hybrid composite samples. This study shows that the addition of jute fiber and glass fiber in epoxy, increases the density, the impact energy, the tensile strength and the flexural strength, but decreases the loss mass in function of temperature and the water absorption. Morphological analysis was carried out to observe fracture behavior and fiber pull-out of the samples using scanning electron microscope. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Coherent Dynamics of a Hybrid Quantum Spin-Mechanical Oscillator System

    Science.gov (United States)

    Lee, Kenneth William, III

    A fully functional quantum computer must contain at least two important components: a quantum memory for storing and manipulating quantum information and a quantum data bus to securely transfer information between quantum memories. Typically, a quantum memory is composed of a matter system, such as an atom or an electron spin, due to their prolonged quantum coherence. Alternatively, a quantum data bus is typically composed of some propagating degree of freedom, such as a photon, which can retain quantum information over long distances. Therefore, a quantum computer will likely be a hybrid quantum device, consisting of two or more disparate quantum systems. However, there must be a reliable and controllable quantum interface between the memory and bus in order to faithfully interconvert quantum information. The current engineering challenge for quantum computers is scaling the device to large numbers of controllable quantum systems, which will ultimately depend on the choice of the quantum elements and interfaces utilized in the device. In this thesis, we present and characterize a hybrid quantum device comprised of single nitrogen-vacancy (NV) centers embedded in a high quality factor diamond mechanical oscillator. The electron spin of the NV center is a leading candidate for the realization of a quantum memory due to its exceptional quantum coherence times. On the other hand, mechanical oscillators are highly sensitive to a wide variety of external forces, and have the potential to serve as a long-range quantum bus between quantum systems of disparate energy scales. These two elements are interfaced through crystal strain generated by vibrations of the mechanical oscillator. Importantly, a strain interface allows for a scalable architecture, and furthermore, opens the door to integration into a larger quantum network through coupling to an optical interface. There are a few important engineering challenges associated with this device. First, there have been no

  7. Actuation of chitosan-aptamer nanobrush borders for pathogen sensing.

    Science.gov (United States)

    Hills, Katherine D; Oliveira, Daniela A; Cavallaro, Nicholas D; Gomes, Carmen L; McLamore, Eric S

    2018-03-26

    We demonstrate a sensing mechanism for rapid detection of Listeria monocytogenes in food samples using the actuation of chitosan-aptamer nanobrush borders. The bio-inspired soft material and sensing strategy mimic natural symbiotic systems, where low levels of bacteria are selectively captured from complex matrices. To engineer this biomimetic system, we first develop reduced graphene oxide/nanoplatinum (rGO-nPt) electrodes, and characterize the fundamental electrochemical behavior in the presence and absence of chitosan nanobrushes during actuation (pH-stimulated osmotic swelling). We then characterize the electrochemical behavior of the nanobrush when receptors (antibodies or DNA aptamers) are conjugated to the surface. Finally, we test various techniques to determine the most efficient capture strategy based on nanobrush actuation, and then apply the biosensors in a food product. Maximum cell capture occurs when aptamers conjugated to the nanobrush bind cells in the extended conformation (pH 6). The aptamer-nanobrush hybrid material was more efficient than the antibody-nanobrush material, which was likely due to the relatively high adsorption capacity for aptamers. The biomimetic material was used to develop a rapid test (17 min) for selectively detecting L. monocytogenes at concentrations ranging from 9 to 107 CFU mL-1 with no pre-concentration, and in the presence of other Gram-positive cells (Listeria innocua and Staphylococcus aureus). Use of this bio-inspired material is among the most efficient for L. monocytogenes sensing to date, and does not require sample pretreatment, making nanobrush borders a promising new material for rapid pathogen detection in food.

  8. Hybrid Quantum Mechanics/Molecular Mechanics/Coarse Grained Modeling: A Triple-Resolution Approach for Biomolecular Systems.

    Science.gov (United States)

    Sokkar, Pandian; Boulanger, Eliot; Thiel, Walter; Sanchez-Garcia, Elsa

    2015-04-14

    We present a hybrid quantum mechanics/molecular mechanics/coarse-grained (QM/MM/CG) multiresolution approach for solvated biomolecular systems. The chemically important active-site region is treated at the QM level. The biomolecular environment is described by an atomistic MM force field, and the solvent is modeled with the CG Martini force field using standard or polarizable (pol-CG) water. Interactions within the QM, MM, and CG regions, and between the QM and MM regions, are treated in the usual manner, whereas the CG-MM and CG-QM interactions are evaluated using the virtual sites approach. The accuracy and efficiency of our implementation is tested for two enzymes, chorismate mutase (CM) and p-hydroxybenzoate hydroxylase (PHBH). In CM, the QM/MM/CG potential energy scans along the reaction coordinate yield reaction energies that are too large, both for the standard and polarizable Martini CG water models, which can be attributed to adverse effects of using large CG water beads. The inclusion of an atomistic MM water layer (10 Å for uncharged CG water and 5 Å for polarizable CG water) around the QM region improves the energy profiles compared to the reference QM/MM calculations. In analogous QM/MM/CG calculations on PHBH, the use of the pol-CG description for the outer water does not affect the stabilization of the highly charged FADHOOH-pOHB transition state compared to the fully atomistic QM/MM calculations. Detailed performance analysis in a glycine-water model system indicates that computation times for QM energy and gradient evaluations at the density functional level are typically reduced by 40-70% for QM/MM/CG relative to fully atomistic QM/MM calculations.

  9. Levitating Micro-Actuators: A Review

    Directory of Open Access Journals (Sweden)

    Kirill V. Poletkin

    2018-04-01

    Full Text Available Through remote forces, levitating micro-actuators completely eliminate mechanical attachment between the stationary and moving parts of a micro-actuator, thus providing a fundamental solution to overcoming the domination of friction over inertial forces at the micro-scale. Eliminating the usual mechanical constraints promises micro-actuators with increased operational capabilities and low dissipation energy. Further reduction of friction and hence dissipation by means of vacuum leads to dramatic increases of performance when compared to mechanically tethered counterparts. In order to efficiently employ the benefits provided by levitation, micro-actuators are classified according to their physical principles as well as by their combinations. Different operating principles, structures, materials and fabrication methods are considered. A detailed analysis of the significant achievements in the technology of micro-optics, micro-magnets and micro-coil fabrication, along with the development of new magnetic materials during recent decades, which has driven the creation of new application domains for levitating micro-actuators is performed.

  10. Effects of Kenaf Fiber Orientation on Mechanical Properties and Fatigue Life of Glass/Kenaf Hybrid Composites

    Directory of Open Access Journals (Sweden)

    Mohaiman Jaffar Sharba

    2015-12-01

    Full Text Available The objectives of this work were to investigate the effect of kenaf fiber alignment on the mechanical and fatigue properties of kenaf/glass hybrid sandwich composites. Three types of kenaf fibers were used, namely, non-woven random mat, unidirectional twisted yarn, and plain-woven kenaf. A symmetric sandwich configuration was constructed with glass as the shell and kenaf as the core with a constant kenaf/glass weight ratio of 30/70% and a volume fraction of 35%. Tensile, compression, flexural, and fully reversed fatigue tests were conducted, and a morphological study of the tensile failure surface of each hybrid composite was carried out. The non-woven mat kenaf hybrid had poor properties for all tests, while the unidirectional kenaf hybrid composite possessed higher tensile strength and similar compressive properties compared with the woven kenaf. Hybridization with kenaf fibers improved the fatigue degradation coefficient of the final composites to 6.2% and 6.4% for woven and unidirectional kenaf, respectively, compared with 7.9% for non-woven. Because woven kenaf hybrid composite is lightweight, environment friendly, and has a considerable balance in static and fatigue strengths with low fatigue sensitivity in bidirectional planes compared to glass, it is strongly recommended for structural applications.

  11. Design and control of a linearity-enhanced SMA actuator

    International Nuclear Information System (INIS)

    Son, Hyung-Min; Tak, Chul-Gon; Lee, Yun-Jung; Kang, Seok-Won; Nam, Tae-Hyun; Kim, Jae-Il

    2010-01-01

    For the accurate and dexterous operation of mechanical systems, continuous-type actuation, rather than on/off-type actuation, is an indispensable function. However, conventional Ti-Ni alloys present difficulties for continuous positioning control, due to their hysteretic and abruptly changing relationship between strain and temperature. Therefore, this paper proposes a new linearity-enhanced SMA actuator using a temperature-gradient annealed alloy and an inverse hysteresis controller. In comparative experiments, the proposed controller and alloy exhibit superior performance for continuous actuation.

  12. Nanoporous carbon actuator and methods of use thereof

    Science.gov (United States)

    Biener, Juergen [San Leandro, CA; Baumann, Theodore F [Discovery Bay, CA; Shao, Lihua [Karlsruhe, DE; Weissmueller, Joerg [Stutensee, DE

    2012-07-31

    An electrochemically driveable actuator according to one embodiment includes a nanoporous carbon aerogel composition capable of exhibiting charge-induced reversible strain when wetted by an electrolyte and a voltage is applied thereto. An electrochemically driven actuator according to another embodiment includes a nanoporous carbon aerogel composition wetted by an electrolyte; and a mechanism for causing charge-induced reversible strain of the composition. A method for electrochemically actuating an object according to one embodiment includes causing charge-induced reversible strain of a nanoporous carbon aerogel composition wetted with an electrolyte to actuate the object by the strain.

  13. Carbon nanotube array actuators

    International Nuclear Information System (INIS)

    Geier, S; Mahrholz, T; Wierach, P; Sinapius, M

    2013-01-01

    Experimental investigations of highly vertically aligned carbon nanotubes (CNTs), also known as CNT-arrays, are the main focus of this paper. The free strain as result of an active material behavior is analyzed via a novel experimental setup. Previous test experiences of papers made of randomly oriented CNTs, also called Bucky-papers, reveal comparably low free strain. The anisotropy of aligned CNTs promises better performance. Via synthesis techniques like chemical vapor deposition (CVD) or plasma enhanced CVD (PECVD), highly aligned arrays of multi-walled carbon nanotubes (MWCNTs) are synthesized. Two different types of CNT-arrays are analyzed, morphologically first, and optically tested for their active characteristics afterwards. One type of the analyzed arrays features tube lengths of 750–2000 μm with a large variety of diameters between 20 and 50 nm and a wave-like CNT-shape. The second type features a maximum, almost uniform, length of 12 μm and a constant diameter of 50 nm. Different CNT-lengths and array types are tested due to their active behavior. As result of the presented tests, it is reported that the quality of orientation is the most decisive property for excellent active behavior. Due to their alignment, CNT-arrays feature the opportunity to clarify the actuation mechanism of architectures made of CNTs. (paper)

  14. A multi-purpose electromagnetic actuator for magnetic resonance elastography.

    Science.gov (United States)

    Feng, Yuan; Zhu, Mo; Qiu, Suhao; Shen, Ping; Ma, Shengyuan; Zhao, Xuefeng; Hu, Chun-Hong; Guo, Liang

    2018-04-19

    An electromagnetic actuator was designed for magnetic resonance elastography (MRE). The actuator is unique in that it is simple, portable, and capable of brain, abdomen, and phantom imagings. A custom-built control unit was used for controlling the vibration frequency and synchronizing the trigger signals. An actuation unit was built and mounted on the specifically designed clamp and holders for different imaging applications. MRE experiments with respect to gel phantoms, brain, and liver showed that the actuator could produce stable and consistent mechanical waves. Estimated shear modulus using local frequency estimate method demonstrated that the measurement results were in line with that from MRE studies using different actuation systems. The relatively easy setup procedure and simple design indicated that the actuator system had the potential to be applied in many different clinical studies. Copyright © 2018 Elsevier Inc. All rights reserved.

  15. Characterization and design of antagonistic shape memory alloy actuators

    International Nuclear Information System (INIS)

    Georges, T; Brailovski, V; Terriault, P

    2012-01-01

    Antagonistic shape memory actuators use opposing shape memory alloy (SMA) elements to create devices capable of producing differential motion paths and two-way mechanical work in a very efficient manner. There is no requirement for additional bias elements to ‘re-arm’ the actuators and allow repetitive actuation. The work generation potential of antagonistic shape memory actuators is determined by specific SMA element characteristics and their assembly conditions. In this study, the selected SMA wires are assembled in antagonistic configuration and characterized using a dedicated test bench to evaluate their stress–strain characteristics as a function of the number of cycles. Using these functional characteristics, a so-called ‘working envelope’ is built to assist in the design of such an actuator. Finally, the test bench is used to simulate a real application of an antagonistic actuator (case study). (paper)

  16. Simulation of the fuel consumption benefits of various transmission arrangements and control strategies within a flywheel based mechanical hybrid system

    Energy Technology Data Exchange (ETDEWEB)

    Body, William; Brockbank, Chris [Torotrak (Development) Ltd. (United Kingdom)

    2009-07-01

    Flywheel based mechanical hybrid technology is being developed for both motorsport and mainstream automotive applications. One particular road car application project, part funded by the UK Government Technology Strategy Board, is being led by Jaguar Land Rover, managed by Prodrive and using advanced technology from Flybrid Systems, Ford, Ricardo. Torotrak and Xtrac. During the two year programme, the group will develop the new technology and build a demonstrator vehicle equipped with the system. The mechanical system recovers kinetic energy from the vehicle during braking to a high speed rotating flywheel via a variable drive system. When compared to an electric motor / battery arrangement, the mechanical hybrid system offers benefits in cost, weight, package, efficiency and ultimately vehicle fuel consumption. As part of the development and optimisation process in order to specify the road car system, all aspects of the mechanical hybrid system are under investigation by the group. Alongside the required quantity of energy storage and the rates of energy recovery and reapplication, a number of different physical architectures for the system are being analysed. The Torotrak full-toroidal traction drive has been assigned as the variable drive element of the mechanical hybrid system. Multiple configuration options are available including direct drive, epicyclic shunted, range extended CVT and epicyclic shunted IVT arrangements. In addition, the flywheel and variable drive system can be connected to the powertrain in a variety of different locations, from the engine through the powertrain to the wheels. This paper describes the simulation of the mechanical hybrid system with particular focus on the impact on the fuel consumption benefit, over multiple drive cycles, of the variable drive configuration, the location of the variable drive and flywheel system and the control strategy options. (orig.)

  17. Pneumatic Muscle Actuator Control

    National Research Council Canada - National Science Library

    Lilly, John

    2000-01-01

    This research is relevant to the Air Fore mission because pneumatic muscle actuation devices arc advantageous for certain types of robotics as well as for strength and/or mobility assistance for humans...

  18. Optical nano and micro actuator technology

    CERN Document Server

    Knopf, George K

    2012-01-01

    In Optical Nano and Micro Actuator Technology, leading engineers, material scientists, chemists, physicists, laser scientists, and manufacturing specialists offer an in-depth, wide-ranging look at the fundamental and unique characteristics of light-driven optical actuators. They discuss how light can initiate physical movement and control a variety of mechanisms that perform mechanical work at the micro- and nanoscale. The book begins with the scientific background necessary for understanding light-driven systems, discussing the nature of light and the interaction between light and NEMS/MEMS d

  19. Recent developments on SMA actuators: predicting the actuation fatigue life for variable loading schemes

    Science.gov (United States)

    Wheeler, Robert W.; Lagoudas, Dimitris C.

    2017-04-01

    Shape memory alloys (SMAs), due to their ability to repeatably recover substantial deformations under applied mechanical loading, have the potential to impact the aerospace, automotive, biomedical, and energy industries as weight and volume saving replacements for conventional actuators. While numerous applications of SMA actuators have been flight tested and can be found in industrial applications, these actuators are generally limited to non-critical components, are not widely implemented and frequently one-off designs, and are generally overdesigned due to a lack of understanding of the effect of the loading path on the fatigue life and the lack of an accurate method for predicting actuator lifetimes. In recent years, multiple research efforts have increased our understanding of the actuation fatigue process of SMAs. These advances can be utilized to predict the fatigue lives and failure loads in SMA actuators. Additionally, these prediction methods can be implemented in order to intelligently design actuators in accordance with their fatigue and failure limits. In the following paper, both simple and complex thermomechanical loading paths have been considered. Experimental data was utilized from two material systems: equiatomic Nickel-Titanium and Nickelrich Nickel-Titanium.

  20. Improved glucose control and reduced body weight in rodents with dual mechanism of action peptide hybrids.

    Directory of Open Access Journals (Sweden)

    James L Trevaskis

    Full Text Available Combination therapy is being increasingly used as a treatment paradigm for metabolic diseases such as diabetes and obesity. In the peptide therapeutics realm, recent work has highlighted the therapeutic potential of chimeric peptides that act on two distinct receptors, thereby harnessing parallel complementary mechanisms to induce additive or synergistic benefit compared to monotherapy. Here, we extend this hypothesis by linking a known anti-diabetic peptide with an anti-obesity peptide into a novel peptide hybrid, which we termed a phybrid. We report on the synthesis and biological activity of two such phybrids (AC164204 and AC164209, comprised of a glucagon-like peptide-1 receptor (GLP1-R agonist, and exenatide analog, AC3082, covalently linked to a second generation amylin analog, davalintide. Both molecules acted as full agonists at their cognate receptors in vitro, albeit with reduced potency at the calcitonin receptor indicating slightly perturbed amylin agonism. In obese diabetic Lep(ob/Lep (ob mice sustained infusion of AC164204 and AC164209 reduced glucose and glycated haemoglobin (HbA1c equivalently but induced greater weight loss relative to exenatide administration alone. Weight loss was similar to that induced by combined administration of exenatide and davalintide. In diet-induced obese rats, both phybrids dose-dependently reduced food intake and body weight to a greater extent than exenatide or davalintide alone, and equal to co-infusion of exenatide and davalintide. Phybrid-mediated and exenatide + davalintide-mediated weight loss was associated with reduced adiposity and preservation of lean mass. These data are the first to provide in vivo proof-of-concept for multi-pathway targeting in metabolic disease via a peptide hybrid, demonstrating that this approach is as effective as co-administration of individual peptides.

  1. Tetherless thermobiochemically actuated microgrippers.

    Science.gov (United States)

    Leong, Timothy G; Randall, Christina L; Benson, Bryan R; Bassik, Noy; Stern, George M; Gracias, David H

    2009-01-20

    We demonstrate mass-producible, tetherless microgrippers that can be remotely triggered by temperature and chemicals under biologically relevant conditions. The microgrippers use a self-contained actuation response, obviating the need for external tethers in operation. The grippers can be actuated en masse, even while spatially separated. We used the microgrippers to perform diverse functions, such as picking up a bead on a substrate and the removal of cells from tissue embedded at the end of a capillary (an in vitro biopsy).

  2. Assessing the degradation of compliant electrodes for soft actuators

    Science.gov (United States)

    Rosset, Samuel; de Saint-Aubin, Christine; Poulin, Alexandre; Shea, Herbert R.

    2017-10-01

    We present an automated system to measure the degradation of compliant electrodes used in dielectric elastomer actuators (DEAs) over millions of cycles. Electrodes for DEAs generally experience biaxial linear strains of more than 10%. The decrease in electrode conductivity induced by this repeated fast mechanical deformation impacts the bandwidth of the actuator and its strain homogeneity. Changes in the electrode mechanical properties lead to reduced actuation strain. Rather than using an external actuator to periodically deform the electrodes, our measurement method consists of measuring the properties of an electrode in an expanding circle DEA. A programmable high voltage power supply drives the actuator with a square signal up to 1 kHz, periodically actuating the DEA, and thus stretching the electrodes. The DEA strain is monitored with a universal serial bus camera, while the resistance of the ground electrode is measured with a multimeter. The system can be used for any type of electrode. We validated the test setup by characterising a carbon black/silicone composite that we commonly use as compliant electrode. Although the composite is well-suited for tens of millions of cycles of actuation below 5%, we observe important degradation for higher deformations. When activated at a 20% radial strain, the electrodes suffer from important damage after a few thousand cycles, and an inhomogeneous actuation is observed, with the strain localised in a sub-region of the actuator only.

  3. A hybrid deterministic-probabilistic approach to model the mechanical response of helically arranged hierarchical strands

    Science.gov (United States)

    Fraldi, M.; Perrella, G.; Ciervo, M.; Bosia, F.; Pugno, N. M.

    2017-09-01

    Very recently, a Weibull-based probabilistic strategy has been successfully applied to bundles of wires to determine their overall stress-strain behaviour, also capturing previously unpredicted nonlinear and post-elastic features of hierarchical strands. This approach is based on the so-called "Equal Load Sharing (ELS)" hypothesis by virtue of which, when a wire breaks, the load acting on the strand is homogeneously redistributed among the surviving wires. Despite the overall effectiveness of the method, some discrepancies between theoretical predictions and in silico Finite Element-based simulations or experimental findings might arise when more complex structures are analysed, e.g. helically arranged bundles. To overcome these limitations, an enhanced hybrid approach is proposed in which the probability of rupture is combined with a deterministic mechanical model of a strand constituted by helically-arranged and hierarchically-organized wires. The analytical model is validated comparing its predictions with both Finite Element simulations and experimental tests. The results show that generalized stress-strain responses - incorporating tension/torsion coupling - are naturally found and, once one or more elements break, the competition between geometry and mechanics of the strand microstructure, i.e. the different cross sections and helical angles of the wires in the different hierarchical levels of the strand, determines the no longer homogeneous stress redistribution among the surviving wires whose fate is hence governed by a "Hierarchical Load Sharing" criterion.

  4. EFFECT OF CLIMATIC FACTOR ON THE MECHANICAL BEHAVIOUR OF AEOLIAN BLADES: APPLICATION OF HYBRID COMPOSITE MATERIALS

    Directory of Open Access Journals (Sweden)

    F. Mili

    2015-08-01

    Full Text Available The great interest which the wind power brings in the development of the various economic sectors encourages to contribute in the improvement of the hydrothermal and mechanical performances of the blades of wind rotors with horizontal axis. The use of composite materials involves a profit of substantial weight, strength to the directional constraints that the blade will undergo during its work and a reduction of the aerodynamic and mechanical losses. The adoption of composite materials with unidirectional reinforcement carbon/epoxy makes it possible to get for the structure a high wear resistance and a reduction of the phenomenon of bearing pressure created around the airfoil of the blade moving relative compared to the speed of the wind. The evaluation of the behavior of such composites with [+θ/- θ]4S stacking sequence, with the combined effect of the temperature, the moisture and the tensile effort constitutes the principal axis of this contribution. In order to minimize the costs, our analysis will direct towards hybrid composite materials glass-carbon/epoxy being presented in the form of symmetrical laminates [+q/0°]2S and antisymmetric [+q/0°/90°/-q]. The results obtained showed that their use contributes to the improvement of their thermomechanical behavior by involving profits of performance, weight, cost savings and energy.

  5. Mechanism of enhanced performance on a hybrid direct carbon fuel cell using sawdust biofuels

    Science.gov (United States)

    Li, Shuangbin; Jiang, Cairong; Liu, Juan; Tao, Haoliang; Meng, Xie; Connor, Paul; Hui, Jianing; Wang, Shaorong; Ma, Jianjun; Irvine, John T. S.

    2018-04-01

    Biomass is expected to play a significant role in power generation in the near future. With the uprising of carbon fuel cells, hybrid direct carbon fuel cells (HDCFCs) show its intrinsic and incomparable advantages in the generation of clean energy with higher efficiency. In this study, two types of biomass treated by physical sieve and pyrolysis from raw sawdust are investigated on an anode-supported HDCFC. The structure and thermal analysis indicate that raw sawdust has well-formed cellulose I phase with very low ash. Electrochemical performance behaviors for sieved and pyrolyzed sawdust combined with various weight ratios of carbonate are compared in N2 and CO2 purge gas. The results show that the power output of sieved sawdust with 789 mWcm-2 is superior to that of pyrolyzed sawdust in CO2 flowing, as well as in N2 flowing. The anode reaction mechanism for the discrepancy of two fuels is explained and the emphasis is also placed on the modified oxygen-reduction cycle mechanism of catalytic effects of Li2CO3 and K2CO3 salts in promoting cell performance.

  6. Self-Healing Natural Rubber with Tailorable Mechanical Properties Based on Ionic Supramolecular Hybrid Network.

    Science.gov (United States)

    Xu, Chuanhui; Cao, Liming; Huang, Xunhui; Chen, Yukun; Lin, Baofeng; Fu, Lihua

    2017-08-30

    In most cases, the strength of self-healing supramolecular rubber based on noncovalent bonds is in the order of KPa, which is a challenge for their further applications. Incorporation of conventional fillers can effectively enhance the strength of rubbers, but usually accompanied by a sacrifice of self-healing capability due to that the filler system is independent of the reversible supramolecular network. In the present work, in situ reaction of methacrylic acid (MAA) and excess zinc oxide (ZnO) was realized in natural rubber (NR). Ionic cross-links in NR matrix were obtained by limiting the covalent cross-linking of NR molecules and allowing the in situ polymerization of MAA/ZnO. Because of the natural affinity between Zn 2+ ion-rich domains and ZnO, the residual nano ZnO participated in formation of a reversible ionic supramolecular hybrid network, thus having little obstructions on the reconstruction of ionic cross-links. Meanwhile, the well dispersed residual ZnO could tailor the mechanical properties of NR by changing the MAA/ZnO molar ratios. The present study thus provides a simple method to fabricate a new self-healing NR with tailorable mechanical properties that may have more potential applications.

  7. Mechanisms of induction of chromosomal aberrations and their detection by fluorescence in situ hybridization

    International Nuclear Information System (INIS)

    Natarajan, A.T.

    2002-01-01

    Recently introduced fluorescence in situ hybridization (FISH) technique employing chromosome specific DNA libraries as well as region specific DNA probes (e.g., centromere, telomere) have helped to analyse chromosomal aberrations in great detail and thus have given some new insights into the mechanisms of induction of chromosomal aberrations. The relative proportion of induction of translocations and dicentrics by ionising radiation was studied in human, mice and Chinese hamster cells. Many of the studies point to the differences between the mechanisms of induction of dicentrics and translocations. Preliminary results obtained in our laboratory using arm specific probes for human chromosomes 1 and 3 indicate that the aberrations between the arms appear to be more than expected on a random basis. By employing telomeric probes the frequencies of interstitial deletions were found to be high and similar to the frequencies of dicentrics both in human and mouse lymphocytes. A recent study with human chromosome specific probes clearly shows variation of sensitivity of chromosomes for the induction of exchange aberrations. Radiation response studies with Chinese hamster cells using telomeric probes, suggest that telomeric sequences, especially interstitial ones appear to be an important factor in the origin of both spontaneous and induced chromosomal aberrations

  8. Elastomer Nanocomposites Based on Butadiene Rubber, Nanoclay and Epoxy-Polyester Hybrid: Microstructure and Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Sepideh Zoghi

    2013-08-01

    Full Text Available Nanocomposites based on butadiene rubber (BR, (0, 3, 5 and 7 phr organoclay (Cloisite 15A and (0, 10, 20, 30, 40 phr powder coating wastes, i.e., epoxypolyester hybrid (EPH were prepared using a laboratory-scale internal mixer in order to study the effect of organoclay and EPH content on the mechanical and morphological properties of the nanocomposite samples. Cure characteristics of the prepared compounds including optimum cure time (t90 and scorch time (t5 depicted a decrease in both mentioned factors with increasing nanoclay content and EPH loading.Intercalation of elastomer chains into the silicate layers was determined by d-spacing values calculated according to the results of X-ray diffraction (XRD patterns. X-ray diffraction (XRD results reveal the intercalation of elastomer chains into the clay galleries. This phenomenon was also confirmed according to the scanning electron microscopy (SEM micrographs and mechanical properties of the nanocomposite samples which were observed to be improved with addition of nanoclay and EPH content.

  9. Soft actuators and soft actuating devices

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Dian; Whitesides, George M.

    2017-10-17

    A soft buckling linear actuator is described, including: a plurality of substantially parallel bucklable, elastic structural components each having its longest dimension along a first axis; and a plurality of secondary structural components each disposed between and bridging two adjacent bucklable, elastic structural components; wherein every two adjacent bucklable, elastic structural components and the secondary structural components in-between define a layer comprising a plurality of cells each capable of being connected with a fluid inflation or deflation source; the secondary structural components from two adjacent layers are not aligned along a second axis perpendicular to the first axis; and the secondary structural components are configured not to buckle, the bucklable, elastic structural components are configured to buckle along the second axis to generate a linear force, upon the inflation or deflation of the cells. Methods of actuation using the same are also described.

  10. Compact electrostatic comb actuator

    Science.gov (United States)

    Rodgers, M. Steven; Burg, Michael S.; Jensen, Brian D.; Miller, Samuel L.; Barnes, Stephen M.

    2000-01-01

    A compact electrostatic comb actuator is disclosed for microelectromechanical (MEM) applications. The actuator is based upon a plurality of meshed electrostatic combs, some of which are stationary and others of which are moveable. One or more restoring springs are fabricated within an outline of the electrostatic combs (i.e. superposed with the moveable electrostatic combs) to considerably reduce the space required for the actuator. Additionally, a truss structure is provided to support the moveable electrostatic combs and prevent bending or distortion of these combs due to unbalanced electrostatic forces or external loading. The truss structure formed about the moveable electrostatic combs allows the spacing between the interdigitated fingers of the combs to be reduced to about one micron or less, thereby substantially increasing the number of active fingers which can be provided in a given area. Finally, electrostatic shields can be used in the actuator to substantially reduce unwanted electrostatic fields to further improve performance of the device. As a result, the compact electrostatic comb actuator of the present invention occupies only a fraction of the space required for conventional electrostatic comb actuators, while providing a substantial increase in the available drive force (up to one-hundred times).

  11. Electromechanical actuation of buckypaper actuator: Material properties and performance relationships

    International Nuclear Information System (INIS)

    Cottinet, P.-J.; Souders, C.; Tsai, S.-Y.; Liang, R.; Wang, B.; Zhang, C.

    2012-01-01

    Carbon nanotubes can be assembled into macroscopic thin film materials called buckypapers. To incorporate buckypaper actuators into engineering systems, it is of high importance to understand their material property-actuation performance relationships in order to model and predict the behavior of these actuators. The electromechanical actuation of macroscopic buckypaper structures and their actuators, including single and multi-walled carbon nanotube buckypapers and aligned single-walled nanotube buckypapers, were analyzed and compared. From the experimental evidence, this Letter discusses the effects of the fundamental material properties, including Young modulus and electrical double layer properties, on actuation performance of the resultant actuators. -- Highlights: ► In this study we identified the figure of merit of the electromechanical conversion. ► Different type of buckypaper was realized and characterized for actuation properties. ► The results demonstrated the potential of Buckypapers/Nafion for actuation

  12. Mechanical Performance of Natural / Natural Fiber Reinforced Hybrid Composite Materials Using Finite Element Method Based Micromechanics and Experiments

    OpenAIRE

    Rahman, Muhammad Ziaur

    2017-01-01

    A micromechanical analysis of the representative volume element (RVE) of a unidirectional flax/jute fiber reinforced epoxy composite is performed using finite element analysis (FEA). To do so, first effective mechanical properties of flax fiber and jute fiber are evaluated numerically and then used in evaluating the effective properties of ax/jute/epoxy hybrid composite. Mechanics of Structure Genome (MSG), a new homogenization tool developed in Purdue University, is used to calculate the hom...

  13. Limit cycles and stiffness control with variable stiffness actuators

    NARCIS (Netherlands)

    Carloni, Raffaella; Marconi, L.

    2012-01-01

    Variable stiffness actuators realize highly dynamic systems, whose inherent mechanical compliance can be properly exploited to obtain a robust and energy-efficient behavior. The paper presents a control strategy for variable stiffness actuators with the primarily goal of tracking a limit cycle

  14. Enhanced mechanical properties and biocompatibility of novel hydroxyapatite/TOPAS hybrid composite for bone tissue engineering applications.

    Science.gov (United States)

    Ain, Qurat Ul; Khan, Ahmad Nawaz; Nabavinia, Mahboubeh; Mujahid, Mohammad

    2017-06-01

    The bioactivity and mechanical properties of hybrid composites of hydroxyapatite (HA) in cyclic olefinic copolymer (COC) also known commercially as TOPAS are investigated, first time, for regeneration and repair of the bone tissues. HA is synthesized to obtain the spherically shaped nanoparticles in the size range of 60±20nm. Various concentrations of HA ranging from 1 to 30wt% are dispersed in TOPAS using sodium dodecyl sulfate (SDS) coupling agent for better dispersion and interaction of hydrophilic HA with hydrophobic TOPAS. Scanning electron microscope shows the uniform dispersion of HA≤10wt% in TOPAS and at higher concentrations >10wt%, agglomeration occurs in the hybrid composites. Tunable mechanical properties are achieved as the compressive modulus and strength are increased around 140% from 6.4 to 15.3MPa and 185% from 0.26 to 0.74MPa, respectively. Such increase in the mechanical properties of TOPAS is attributed to the anchoring of the polymer chains in the vicinity of HA nanoparticles owing to better dispersion and interfacial interactions. In comparison to neat TOPAS, hybrid composites of TOPAS/HA promoted the cell adhesion and proliferation significantly. The cell density and proliferation of TOPAS/HA hybrid composites is enhanced 9 and 3 folds, respectively, after 1day culturing in preosteoblasts cells. Moreover, the morphology of cells changed from spherical to flattened spread morphology demonstrating clearly the migration of the cells for the formation of interconnected cellular network. Additionally, very few dead cells are found in hybrid composites showing their cytocompatibility. Overall, the hybrid composites of TOPAS/HA exhibited superior strength and stiffness along with enhanced cytocompatibility for bone tissue engineering applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Mechanical characterization of hybrid and functionally-graded aluminum open-cell foams with nanocrystalline-copper coatings

    Science.gov (United States)

    Sun, Yi

    Cellular/foam materials found in nature such as bone, wood, and bamboo are usually functionally graded by having a non-uniform density distribution and inhomogenous composition that optimizes their global mechanical performance. Inspired by such naturally engineered products, the current study was conducted towards the development of functionally graded hybrid metal foams (FGHMF) with electrodeposited (ED) nanocrystalline coatings. First, the deformation and failure mechanisms of aluminum/copper (Al/Cu) hybrid foams were investigated using finite element analyses at different scales. The micro-scale behavior was studied based on single ligament models discretized using continuum elements and the macro-scale behavior was investigated using beam-element based finite element models of representative unit volumes consisting of multiple foam cells. With a detailed constitutive material behavior and material failure considered for both the aluminum ligament and the nano-copper coating, the numerical models were able to capture the unique behavior of Al/Cu hybrid foams, such as the typically observed sudden load drop after yielding. The numerical models indicate that such load drop is caused by the fracture of foam ligaments initiated from the rupture of the ED nano-copper coating due to its low ductility. This failure mode jeopardizes the global energy absorption capacity of hybrid foams, especially when a thick coating is applied. With the purpose of enhancing the performance of Al/Cu hybrid foams, an annealing process, which increased the ductility of the nanocrystalline copper coating by causing recovery, recrystallination and grain growth, was introduced in the manufacturing of Al/Cu hybrid foams. Quasi-static experimental results indicate that when a proper amount of annealing is applied, the ductility of the ED copper can be effectively improved and the compressive and tensile behavior of Al/Cu hybrid foams can be significantly enhanced, including better energy

  16. Mechanistic insights into Mg2+-independent prenylation by CloQ from classical molecular mechanics and hybrid quantum mechanics/molecular mechanics molecular dynamics simulations.

    Science.gov (United States)

    Bayse, Craig A; Merz, Kenneth M

    2014-08-05

    Understanding the mechanism of prenyltransferases is important to the design of engineered proteins capable of synthesizing derivatives of naturally occurring therapeutic agents. CloQ is a Mg(2+)-independent aromatic prenyltransferase (APTase) that transfers a dimethylallyl group to 4-hydroxyphenylpyruvate in the biosynthetic pathway for clorobiocin. APTases consist of a common ABBA fold that defines a β-barrel containing the reaction cavity. Positively charged basic residues line the inside of the β-barrel of CloQ to activate the pyrophosphate leaving group to replace the function of the Mg(2+) cofactor in other APTases. Classical molecular dynamics simulations of CloQ, its E281G and F68S mutants, and the related NovQ were used to explore the binding of the 4-hydroxyphenylpyruvate (4HPP) and dimethylallyl diphosphate substrates in the reactive cavity and the role of various conserved residues. Hybrid quantum mechanics/molecular mechanics potential of mean force (PMF) calculations show that the effect of the replacement of the Mg(2+) cofactor with basic residues yields a similar activation barrier for prenylation to Mg(2+)-dependent APTases like NphB. The topology of the binding pocket for 4HPP is important for selective prenylation at the ortho position of the ring. Methylation at this position alters the conformation of the substrate for O-prenylation at the phenol group. Further, a two-dimensional PMF scan shows that a "reverse" prenylation product may be a possible target for protein engineering.

  17. Graphene-nanoplatelet-based photomechanical actuators

    International Nuclear Information System (INIS)

    Loomis, James; King, Ben; Burkhead, Tom; Xu Peng; Bessler, Nathan; Panchapakesan, Balaji; Terentjev, Eugene

    2012-01-01

    This paper reports large light-induced reversible and elastic responses of graphene nanoplatelet (GNP) polymer composites. Homogeneous mixtures of GNP/polydimethylsiloxane (PDMS) composites (0.1–5 wt%) were prepared and their infrared (IR) mechanical responses studied with increasing pre-strains. Using IR illumination, a photomechanically induced change in stress of four orders of magnitude as compared to pristine PDMS polymer was measured. The actuation responses of the graphene polymer composites depended on the applied pre-strains. At low levels of pre-strain (3–9%) the actuators showed reversible expansion while at high levels (15–40%) the actuators exhibited reversible contraction. The GNP/PDMS composites exhibited higher actuation stresses compared to other forms of nanostructured carbon/PDMS composites, including carbon nanotubes (CNTs), for the same fabrication method. An extraordinary optical-to-mechanical energy conversion factor (η M ) of 7–9 MPa W −1 for GNP-based polymer composite actuators is reported. (paper)

  18. Dynamic Coordinated Shifting Control of Automated Mechanical Transmissions without a Clutch in a Plug-In Hybrid Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Xinlei Liu

    2012-08-01

    Full Text Available On the basis of the shifting process of automated mechanical transmissions (AMTs for traditional hybrid electric vehicles (HEVs, and by combining the features of electric machines with fast response speed, the dynamic model of the hybrid electric AMT vehicle powertrain is built up, the dynamic characteristics of each phase of shifting process are analyzed, and a control strategy in which torque and speed of the engine and electric machine are coordinatively controlled to achieve AMT shifting control for a plug-in hybrid electric vehicle (PHEV without clutch is proposed. In the shifting process, the engine and electric machine are well controlled, and the shift jerk and power interruption and restoration time are reduced. Simulation and real car test results show that the proposed control strategy can more efficiently improve the shift quality for PHEVs equipped with AMTs.

  19. Optimization of Actuating Origami Networks

    Science.gov (United States)

    Buskohl, Philip; Fuchi, Kazuko; Bazzan, Giorgio; Joo, James; Gregory, Reich; Vaia, Richard

    2015-03-01

    Origami structures morph between 2D and 3D conformations along predetermined fold lines that efficiently program the form, function and mobility of the structure. By leveraging design concepts from action origami, a subset of origami art focused on kinematic mechanisms, reversible folding patterns for applications such as solar array packaging, tunable antennae, and deployable sensing platforms may be designed. However, the enormity of the design space and the need to identify the requisite actuation forces within the structure places a severe limitation on design strategies based on intuition and geometry alone. The present work proposes a topology optimization method, using truss and frame element analysis, to distribute foldline mechanical properties within a reference crease pattern. Known actuating patterns are placed within a reference grid and the optimizer adjusts the fold stiffness of the network to optimally connect them. Design objectives may include a target motion, stress level, or mechanical energy distribution. Results include the validation of known action origami structures and their optimal connectivity within a larger network. This design suite offers an important step toward systematic incorporation of origami design concepts into new, novel and reconfigurable engineering devices. This research is supported under the Air Force Office of Scientific Research (AFOSR) funding, LRIR 13RQ02COR.

  20. Crystallisation of hydroxyapatite in phosphorylated poly(vinyl alcohol) as a synthetic route to tough mechanical hybrid materials

    Energy Technology Data Exchange (ETDEWEB)

    Kusakabe, Akane; Hirota, Ken; Mizutani, Tadashi, E-mail: tmizutan@mail.doshisha.ac.jp

    2017-01-01

    Partially phosphorylated poly(vinyl alcohol) was prepared by treating poly(vinyl alcohol) with 100% phosphoric acid, and 5, 10 and 20% of the hydroxyl groups were converted to phosphoric acid ester. Addition of Ca{sup 2+} to an aqueous solution of phosphorylated poly(vinyl alcohol) gave a transparent gel. Five cycles of alternate soaking of the gel in aqueous CaCl{sub 2} and aqueous (NH{sub 4}){sub 2}HPO{sub 4} were carried out to crystallise hydroxyapatite (HAP) in the phosphorylated poly(vinyl alcohol) matrix. The X-ray diffraction peaks of HAP formed in 5% phosphorylated PVA were sharp, while those of HAP formed in 20% phosphorylated PVA were broad. The contents of inorganic phase in the hybrid powder were increased from 58 to 76 wt% as the fraction of phosphate groups in the gel was decreased from 20% to 5%. The hybrid powder was first subjected to uniaxial pressing, followed by cold isostatic pressing (CIP) and warm isostatic pressing (WIP) at 120 °C at pressures of 300–980 MPa, to obtain the specimens for three-point bending test. These hybrid specimens showed bending strengths of 15–53 MPa. The hybrid compacts prepared from 10% phosphorylated poly(vinyl alcohol) showed the smallest Young's modulus, the largest displacement at break, and the largest fracture energy, showing that it has the highest toughness among the hybrid materials prepared from poly(vinyl alcohol) with varying degrees of phosphorylation. - Graphical abstract: Densification of hydroxyapatite crystallised in 10% phosphorylated poly(vinyl alcohol) gave the toughest compact. - Highlights: • Hydroxyapatite was crystallised in phosphorylated poly(vinyl alcohol) gels. • Crystallite size of hydroxyapatite decreased as phosphate density was increased. • The hybrid specimens prepared in 10% phosphorylated gel was the toughest. • Phosphate density in organic matrix regulated the mechanical properties of the hybrid.

  1. Crystallisation of hydroxyapatite in phosphorylated poly(vinyl alcohol) as a synthetic route to tough mechanical hybrid materials

    International Nuclear Information System (INIS)

    Kusakabe, Akane; Hirota, Ken; Mizutani, Tadashi

    2017-01-01

    Partially phosphorylated poly(vinyl alcohol) was prepared by treating poly(vinyl alcohol) with 100% phosphoric acid, and 5, 10 and 20% of the hydroxyl groups were converted to phosphoric acid ester. Addition of Ca 2+ to an aqueous solution of phosphorylated poly(vinyl alcohol) gave a transparent gel. Five cycles of alternate soaking of the gel in aqueous CaCl 2 and aqueous (NH 4 ) 2 HPO 4 were carried out to crystallise hydroxyapatite (HAP) in the phosphorylated poly(vinyl alcohol) matrix. The X-ray diffraction peaks of HAP formed in 5% phosphorylated PVA were sharp, while those of HAP formed in 20% phosphorylated PVA were broad. The contents of inorganic phase in the hybrid powder were increased from 58 to 76 wt% as the fraction of phosphate groups in the gel was decreased from 20% to 5%. The hybrid powder was first subjected to uniaxial pressing, followed by cold isostatic pressing (CIP) and warm isostatic pressing (WIP) at 120 °C at pressures of 300–980 MPa, to obtain the specimens for three-point bending test. These hybrid specimens showed bending strengths of 15–53 MPa. The hybrid compacts prepared from 10% phosphorylated poly(vinyl alcohol) showed the smallest Young's modulus, the largest displacement at break, and the largest fracture energy, showing that it has the highest toughness among the hybrid materials prepared from poly(vinyl alcohol) with varying degrees of phosphorylation. - Graphical abstract: Densification of hydroxyapatite crystallised in 10% phosphorylated poly(vinyl alcohol) gave the toughest compact. - Highlights: • Hydroxyapatite was crystallised in phosphorylated poly(vinyl alcohol) gels. • Crystallite size of hydroxyapatite decreased as phosphate density was increased. • The hybrid specimens prepared in 10% phosphorylated gel was the toughest. • Phosphate density in organic matrix regulated the mechanical properties of the hybrid.

  2. Investigation of the Mechanical Properties of Hybrid Carbon-Hemp Laminated Composites Used as Thermal Insulation for Different Industrial Applications

    Directory of Open Access Journals (Sweden)

    M. L. Scutaru

    2014-04-01

    Full Text Available Carbon-hemp composite laminate provides good thermal properties. For this reason this type of material is presently being used for various applications like insulator for airplanes, spaceships, nuclear reactors, and so forth. Unfortunately their mechanical properties are less studied. These characteristics are very important since they should be guaranteed also for important mechanical stress in addition to the thermal one. The present paper presents a study regarding the impact testing of some hybrid composite laminate panels based on polyester resin reinforced with both carbon and hemp fabric. The effects of different impact speeds on the mechanical behavior of these panels have been analyzed. The paper lays stress on the characterization of this hybrid composite laminate regarding the impact behavior of these panels by dropping a weight with low velocity.

  3. Stretchable Materials for Robust Soft Actuators towards Assistive Wearable Devices

    Science.gov (United States)

    Agarwal, Gunjan; Besuchet, Nicolas; Audergon, Basile; Paik, Jamie

    2016-09-01

    Soft actuators made from elastomeric active materials can find widespread potential implementation in a variety of applications ranging from assistive wearable technologies targeted at biomedical rehabilitation or assistance with activities of daily living, bioinspired and biomimetic systems, to gripping and manipulating fragile objects, and adaptable locomotion. In this manuscript, we propose a novel two-component soft actuator design and design tool that produces actuators targeted towards these applications with enhanced mechanical performance and manufacturability. Our numerical models developed using the finite element method can predict the actuator behavior at large mechanical strains to allow efficient design iterations for system optimization. Based on two distinctive actuator prototypes’ (linear and bending actuators) experimental results that include free displacement and blocked-forces, we have validated the efficacy of the numerical models. The presented extensive investigation of mechanical performance for soft actuators with varying geometric parameters demonstrates the practical application of the design tool, and the robustness of the actuator hardware design, towards diverse soft robotic systems for a wide set of assistive wearable technologies, including replicating the motion of several parts of the human body.

  4. CSP-based chemical kinetics mechanisms simplification strategy for non-premixed combustion: An application to hybrid rocket propulsion

    KAUST Repository

    Ciottoli, Pietro P.

    2017-08-14

    A set of simplified chemical kinetics mechanisms for hybrid rocket applications using gaseous oxygen (GOX) and hydroxyl-terminated polybutadiene (HTPB) is proposed. The starting point is a 561-species, 2538-reactions, detailed chemical kinetics mechanism for hydrocarbon combustion. This mechanism is used for predictions of the oxidation of butadiene, the primary HTPB pyrolysis product. A Computational Singular Perturbation (CSP) based simplification strategy for non-premixed combustion is proposed. The simplification algorithm is fed with the steady-solutions of classical flamelet equations, these being representative of the non-premixed nature of the combustion processes characterizing a hybrid rocket combustion chamber. The adopted flamelet steady-state solutions are obtained employing pure butadiene and gaseous oxygen as fuel and oxidizer boundary conditions, respectively, for a range of imposed values of strain rate and background pressure. Three simplified chemical mechanisms, each comprising less than 20 species, are obtained for three different pressure values, 3, 17, and 36 bar, selected in accordance with an experimental test campaign of lab-scale hybrid rocket static firings. Finally, a comprehensive strategy is shown to provide simplified mechanisms capable of reproducing the main flame features in the whole pressure range considered.

  5. Switch-mode High Voltage Drivers for Dielectric Electro Active Polymer (DEAP) Incremental Actuators

    DEFF Research Database (Denmark)

    Thummala, Prasanth

    voltage DC-DC converters for driving the DEAP based incremental actuators. The DEAP incremental actuator technology has the potential to be used in various industries, e.g., automotive, space and medicine. The DEAP incremental actuator consists of three electrically isolated and mechanically connected...

  6. Model and Design of a Power Driver for Piezoelectric Stack Actuators

    Directory of Open Access Journals (Sweden)

    Chiaberge M

    2010-01-01

    Full Text Available A power driver has been developed to control piezoelectric stack actuators used in automotive application. An FEM model of the actuator has been implemented starting from experimental characterization of the stack and mechanical and piezoelectric parameters. Experimental results are reported to show a correct piezoelectric actuator driving method and the possibility to obtain a sensorless positioning control.

  7. The porosity formation mechanism in the laser-MIG hybrid welded joint of Invar alloy

    Science.gov (United States)

    Zhan, Xiaohong; Gao, Qiyu; Gu, Cheng; Sun, Weihua; Chen, Jicheng; Wei, Yanhong

    2017-10-01

    The porosity formation mechanism in the laser-metal inter gas (MIG) multi-layer hybrid welded (HW) joint of 19.05 mm thick Invar alloy is investigated. The microstructure characteristics and energy dispersive spectroscopy (EDS) are analyzed. The phase identification was conducted by the X-ray diffractometer (XRD). Experimental results show that the generation of porosity is caused by the relatively low laser power in the root pass and low current in the cover pass. It is also indicated that the microstructures of the welded joints are mainly observed to be columnar crystal and equiaxial crystal, which are closely related to the porosity formation. The EDS results show that oxygen content is significantly high in the inner wall of the porosity. The XRD results indicate that the BM and the WB of laser-MIG HW all are composed of Fe0.64Ni0.36 and γ-(Fe,Ni). When the weld pool is cooled quickly, [NiO] [FeO] and [MnO] are formed that react on C to generate CO/CO2 gases. The porosity of laser-MIG HW for Invar alloy is oxygen pore. The root source of metallurgy porosity formation is that the dissolved gases are hard to escape sufficiently and thus exist in the weld pool. Furthermore, 99.99% pure Argon is recommended as protective gas in the laser-MIG HW of Invar alloy.

  8. Largely enhanced thermal and mechanical properties of polymer nanocomposites via incorporating C60@graphene nanocarbon hybrid

    International Nuclear Information System (INIS)

    Song, Ping’an; Liu, Lina; Yu, Youming; Huang, Guobo; Guo, Qipeng

    2013-01-01

    Although considerable progress has been achieved to create advanced polymer nanocomposites using nanocarbons including fullerene (C 60 ) and graphene, it remains a major challenge to effectively disperse them in a polymer matrix and to fully exert their extraordinary properties. Here we report a novel approach to fabricate the C 60 @graphene nanocarbon hybrid (C 60 : ∼47.9 wt%, graphene: ∼35.1%) via three-step reactions. The presence of C 60 on a graphene sheet surface can effectively prevent the aggregation of the latter which in turn helps the dispersion of the former in a polymer matrix during melt-processing. C 60 @graphene is found to be uniformly dispersed in a polypropylene (PP) matrix. Compared with pristine C 60 or graphene, C 60 @graphene further improves the thermal stability and mechanical properties of PP. The incorporation of 2.0 wt% C 60 @graphene (relative to PP) can remarkably increase the initial degradation temperature by around 59 ° C and simultaneously enhance the tensile strength and Young’s modulus by 67% and 76%, respectively, all of which are higher than those of corresponding PP/C 60 (graphene) nanocomposites. These significant performance improvements are mainly due to the free-radical-trapping effect of C 60 , and the thermal barrier and reinforcing effects of graphene nanosheets as well as the effective stress load transfer. This work provides a new methodology to design multifunctional nanohybrids for creating advanced materials. (paper)

  9. Carrier transport mechanisms of hybrid ZnO nanorod-polymer LEDs

    International Nuclear Information System (INIS)

    Cho, Sungjae; Lee, Kyuseung; Son, Dongick; Oh, Youngjei; Choi, Wonkook; Angadi, Basavaraj

    2014-01-01

    A hybrid polymer-nanorod (NR) light-emitting diode (LED), consisting of a hole-conducting polymer poly (9-vinyl carbazole) (PVK) and ZnO nanorod (NR) composite, with the device structure of glass/indium-tin-oxide (ITO)/PEDOT:PSS/(PVK + ZnO nanorods)/Al is fabricated through a simple spin coating technique. TEM images shows inhomogeneous deposition and the agglomeration of ZnO NRs, which is explained through their low probability of adsorption on PVK due to two-dimensional structural property. In the current-voltage characteristics, negative differential resistance (NDR) phenomenon is observed corresponding to device structure without ZnO NRs. The carrier transport behavior in the LED device is well described by both ohmic and space-charge-limited-current (SCLC) mechanisms. Broad blue electroluminescence (EL) consisting of two sub peaks, are centered at 441 nm and the other at 495 nm, is observed, which indicates that the ZnO nanorod play a role as a recombination center for excitons. The red shift in the position of the EL compared to that photoluminescence is well explained through band offsets at the heterojunction between the PVK and ZnO NRs.

  10. A Hybrid Dynamic Programming for Solving Fixed Cost Transportation with Discounted Mechanism

    Directory of Open Access Journals (Sweden)

    Farhad Ghassemi Tari

    2016-01-01

    Full Text Available The problem of allocating different types of vehicles for transporting a set of products from a manufacturer to its depots/cross docks, in an existing transportation network, to minimize the total transportation costs, is considered. The distribution network involves a heterogeneous fleet of vehicles, with a variable transportation cost and a fixed cost in which a discount mechanism is applied on the fixed part of the transportation costs. It is assumed that the number of available vehicles is limited for some types. A mathematical programming model in the form of the discrete nonlinear optimization model is proposed. A hybrid dynamic programming algorithm is developed for finding the optimal solution. To increase the computational efficiency of the solution algorithm, several concepts and routines, such as the imbedded state routine, surrogate constraint concept, and bounding schemes, are incorporated in the dynamic programming algorithm. A real world case problem is selected and solved by the proposed solution algorithm, and the optimal solution is obtained.

  11. Mechanical Properties of High Volume Fly Ash Concrete Reinforced with Hybrid Fibers

    Directory of Open Access Journals (Sweden)

    Rooban Chakravarthy

    2016-01-01

    Full Text Available Fly ash substitution to cement is a well-recognized approach to reduce CO2 emissions. Although fly ash concrete is prone to brittle behavior, researchers have shown that addition of fibers could reduce brittle behavior. Previous research efforts seem to have utlised a single type of fiber or two types of fibers. In this research, three types of fibers, steel, polypropylene, and basalt as 0%, 0.50%, 0.75%, and 1% by volume of concrete, were mixed in varying proportions with concrete specimens substituted with 50% fly ash (class F. All specimens were tested for compressive strength, indirect tensile strength, and flexural strength over a period of 3 to 56 days of curing. Test results showed that significant improvement in mechanical properties could be obtained by a particular hybrid fiber reinforcement combination (1% steel fiber, 0.75% polypropylene fiber, and 0.75% basalt fiber. The strength values were observed to exceed previous research results. Workability of concrete was affected when the fiber combination exceeded 3%. Thus a limiting value for adding fibers and the combination to achieve maximum strengths have been identified in this research.

  12. Digital Actuator Technology

    Energy Technology Data Exchange (ETDEWEB)

    Ken Thomas; Ted Quinn; Jerry Mauck; Richard Bockhorst

    2014-09-01

    There are significant developments underway in new types of actuators for power plant active components. Many of these make use of digital technology to provide a wide array of benefits in performance of the actuators and in reduced burden to maintain them. These new product offerings have gained considerable acceptance in use in process plants. In addition, they have been used in conventional power generation very successfully. This technology has been proven to deliver the benefits promised and substantiate the claims of improved performance. The nuclear industry has been reluctant to incorporate digital actuator technology into nuclear plant designs due to concerns due to a number of concerns. These could be summarized as cost, regulatory uncertainty, and a certain comfort factor with legacy analog technology. The replacement opportunity for these types of components represents a decision point for whether to invest in more modern technology that would provide superior operational and maintenance benefits. Yet, the application of digital technology has been problematic for the nuclear industry, due to qualification and regulatory issues. With some notable exceptions, the result has been a continuing reluctance to undertake the risks and uncertainties of implementing digital actuator technology when replacement opportunities present themselves. Rather, utilities would typically prefer to accept the performance limitations of the legacy analog actuator technologies to avoid impacts to project costs and schedules. The purpose of this report is to demonstrate that the benefits of digital actuator technology can be significant in terms of plant performance and that it is worthwhile to address the barriers currently holding back the widespread development and use of this technology. It addresses two important objectives in pursuit of the beneficial use of digital actuator technology for nuclear power plants: 1. To demonstrate the benefits of digital actuator

  13. hybrid effect on the mechanical properties of sisal fiber and e-glass

    African Journals Online (AJOL)

    cles was added and the “mix” was vigorously stirred and poured into a mould. Appropriate quantities of fibers (sisal or E-glass) were im- pregnated in the “resin mix” which ultimately cured to give a solid laminate. 2.3. Tensile test. Standard tensile specimens were cut from the hybrid and non-hybrid composite lami-. Nigerian ...

  14. Actuators based on polyurethanes with different types of polyol

    Science.gov (United States)

    Lim, Hyun-Ok; Bark, Geong-Mi; Jo, Nam-Ju

    2007-07-01

    This study dealt with the electrostrictive responses of polyurethane (PU) actuators with different microphase separation structure, which was a promising candidate for a material used in polymer actuators. In order to construct PUs with different higher-order structure, we synthesized PUs with different diols; poly(neopentyl glycol adipate) (PNAD), poly(tetramethylene glycol) (PTMG), and poly(dimethyl siloxnae) (PDMS). Synthesized PU was characterized by FT-IR spectroscopy and GPC. Thermal analysis and mechanical properties of PU films were carried out with DSC and UTM, respectively. And PU actuator was formed in a monomorph type which made by carbon black electrodes on the both surfaces of PU film by spin coating method. Actuation behavior was mainly influenced on microphase separation structure and mechanical property of PU. In result, PU actuator with PNAD, polyester urethane, had the largest field-induced displacement.

  15. Role of hybrid ratio in microstructural, mechanical and sliding wear properties of the Al5083/Graphitep/Al2O3p a surface hybrid nanocomposite fabricated via friction stir processing method

    International Nuclear Information System (INIS)

    Mostafapour Asl, A.; Khandani, S.T.

    2013-01-01

    Hybrid ratio of each reinforcement phase in hybrid composite can be defined as proportion of its volume to total reinforcement volume of the composite. The hybrid ratio is an important factor which controls the participation extent of each reinforcement phase in overall properties of hybrid composites. Hence, in the present work, surface hybrid nanocomposites of Al5083/Graphite p /Al 2 O 3p with different hybrid ratios were fabricated by friction stir processing method. Subsequently, effect of hybrid ratio on microstructural, mechanical and tribological properties of the nanocomposite was investigated. Optical microscopy and scanning electron microscopy were utilized to perform microstructural observation on the samples. Hardness value measurements, tensile and pin on disk dry sliding wear tests were carried out to investigate effect of hybrid ratio on mechanical and tribological properties of the nanocomposites. Microstructural investigations displayed better distribution with less agglomeration of reinforcement for lower volume fraction of reinforcement for both alumina and graphite particles. Hardness value, yield strength, ultimate tensile strength and wear rate of the nanocomposites revealed a two stage form along with hybrid ratio variation. The results are discussed based on microstructural observations of the nanocomposites and worn surface analyses.

  16. Short bursts of cyclic mechanical compression modulate tissue formation in a 3D hybrid scaffold.

    Science.gov (United States)

    Brunelli, M; Perrault, C M; Lacroix, D

    2017-07-01

    Among the cues affecting cells behaviour, mechanical stimuli are known to have a key role in tissue formation and mineralization of bone cells. While soft scaffolds are better at mimicking the extracellular environment, they cannot withstand the high loads required to be efficient substitutes for bone in vivo. We propose a 3D hybrid scaffold combining the load-bearing capabilities of polycaprolactone (PCL) and the ECM-like chemistry of collagen gel to support the dynamic mechanical differentiation of human embryonic mesodermal progenitor cells (hES-MPs). In this study, hES-MPs were cultured in vitro and a BOSE Bioreactor was employed to induce cells differentiation by mechanical stimulation. From day 6, samples were compressed by applying a 5% strain ramp followed by peak-to-peak 1% strain sinewaves at 1Hz for 15min. Three different conditions were tested: unloaded (U), loaded from day 6 to day 10 (L1) and loaded as L1 and from day 16 to day 20 (L2). Cell viability, DNA content and osteocalcin expression were tested. Samples were further stained with 1% osmium tetroxide in order to investigate tissue growth and mineral deposition by micro-computed tomography (µCT). Tissue growth involved volumes either inside or outside samples at day 21 for L1, suggesting cyclic stimulation is a trigger for delayed proliferative response of cells. Cyclic load also had a role in the mineralization process preventing mineral deposition when applied at the early stage of culture. Conversely, cyclic load during the late stage of culture on pre-compressed samples induced mineral formation. This study shows that short bursts of compression applied at different stages of culture have contrasting effects on the ability of hES-MPs to induce tissue formation and mineral deposition. The results pave the way for a new approach using mechanical stimulation in the development of engineered in vitro tissue as replacement for large bone fractures. Copyright © 2017 Elsevier Ltd. All rights

  17. Influence of natural and synthetic crosslinking reagents on the structural and mechanical properties of chitosan-based hybrid hydrogels.

    Science.gov (United States)

    Garnica-Palafox, I M; Sánchez-Arévalo, F M

    2016-10-20

    The objective of this work was to correlate the physical and chemical properties of chitosan/poly(vinyl alcohol)/genipin (CS/PVA/GEN) and chitosan/poly(vinyl alcohol)/glutaraldehyde (CS/PVA/GA) hydrogels with their structural and mechanical responses. In addition, their molecular structures were determined and confirmed using FTIR spectroscopy. The results indicated that the hybrid hydrogels crosslinked with genipin showed similar crystallinity, thermal properties, elongation ratio and structural parameters as those crosslinked with glutaraldehyde. However, it was found that the elastic moduli of the two hybrid hydrogels were slightly different: 2.82±0.33MPa and 2.08±0.11MPa for GA and GEN, respectively. Although the hybrid hydrogels crosslinked with GEN presented a lower elastic modulus, the main advantage is that GEN is five to ten thousand times less cytotoxic than GA. This means that the structural and mechanical properties of hybrid hydrogels crosslinked with GEN can easily be tuned and could have potential applications in the tissue engineering, regenerative medicine, food, agriculture and environmental industries. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Emergency scram actuation device for nuclear reactors

    International Nuclear Information System (INIS)

    Noyes, R.C.; Zaman, S.U.; Stuteville, D.W.

    1979-01-01

    The safety parameter employed for emergency scrams of a liquid metal cooled reactor is the coolant pressure. An actuation bellows is provided which is connected to a measuring chamber by means of a flow system. Both units are installed in a coolant flow section. The measuring chamber proper is connected with the coolant by means of an aperture limiting the flow. Inside the measuring chamber there is an expansion space filled with gas. Pressure changes in the coolant affect the pressure in the expansion space. Expansion of the bellows actuates the release mechanism. (DG) [de

  19. Analysis of the mechanical and thermal properties of jute and glass fiber as reinforcement epoxy hybrid composites

    Energy Technology Data Exchange (ETDEWEB)

    Braga, R.A., E-mail: roney.braga@fiat.com.br [FIAT Automóveis S.A., Teardown, CEP 32530-000 Betim, MG (Brazil); Magalhaes, P.A.A., E-mail: pamerico@pucminas.br [PUC—MINAS, Instituto Politécnico, CEP 30535-610 Belo Horizonte, MG (Brazil)

    2015-11-01

    This work describes the study to investigate and compare the mechanical and thermal properties of raw jute and glass fiber reinforced epoxy hybrid composites. To improve the mechanical properties, jute fiber was hybridized with glass fiber. Epoxy resin, jute and glass fibers were laminated in three weight ratios (69/31/0, 68/25/7 and 64/18/19) respectively to form composites. The tensile, flexural, impact, density, thermal and water absorption tests were carried out using hybrid composite samples. This study shows that the addition of jute fiber and glass fiber in epoxy, increases the density, the impact energy, the tensile strength and the flexural strength, but decreases the loss mass in function of temperature and the water absorption. Morphological analysis was carried out to observe fracture behavior and fiber pull-out of the samples using scanning electron microscope. - Highlights: • The work is the study of the mechanical of raw jute and glass fiber with epoxy resin. • The mechanical properties increased with more proportions of glass fibers. • The density of E69-J31-V0 was the lower. • The flexural strength did not have a significant increase. • The water absorption of E69-J31-V0 was the best.

  20. Biomimetic Hybridization of Kevlar into Silk Fibroin: Nanofibrous Strategy for Improved Mechanic Properties of Flexible Composites and Filtration Membranes.

    Science.gov (United States)

    Lv, Lili; Han, Xiangsheng; Zong, Lu; Li, Mingjie; You, Jun; Wu, Xiaochen; Li, Chaoxu

    2017-08-22

    Silk, one of the strongest natural biopolymers, was hybridized with Kevlar, one of the strongest synthetic polymers, through a biomimetic nanofibrous strategy. Regenerated silk materials have outstanding properties in transparency, biocompatibility, biodegradability and sustainability, and promising applications as diverse as in pharmaceutics, electronics, photonic devices and membranes. To compete with super mechanic properties of their natural counterpart, regenerated silk materials have been hybridized with inorganic fillers such as graphene and carbon nanotubes, but frequently lose essential mechanic flexibility. Inspired by the nanofibrous strategy of natural biomaterials (e.g., silk fibers, hemp and byssal threads of mussels) for fantastic mechanic properties, Kevlar was integrated in regenerated silk materials by combining nanometric fibrillation with proper hydrothermal treatments. The resultant hybrid films showed an ultimate stress and Young's modulus two times as high as those of pure regenerated SF films. This is not only because of the reinforcing effect of Kevlar nanofibrils, but also because of the increasing content of silk β-sheets. When introducing Kevlar nanofibrils into the membranes of silk nanofibrils assembled by regenerated silk fibroin, the improved mechanic properties further enabled potential applications as pressure-driven nanofiltration membranes and flexible substrates of electronic devices.

  1. Fiber-Reinforced Origamic Robotic Actuator.

    Science.gov (United States)

    Yi, Juan; Chen, Xiaojiao; Song, Chaoyang; Wang, Zheng

    2018-02-01

    A novel pneumatic soft linear actuator Fiber-reinforced Origamic Robotic Actuator (FORA) is proposed with significant improvements on the popular McKibben-type actuators, offering nearly doubled motion range, substantially improved force profile, and significantly lower actuation pressure. The desirable feature set is made possible by a novel soft origamic chamber that expands radially while contracts axially when pressurized. Combining this new origamic chamber with a reinforcing fiber mesh, FORA generates very high traction force (over 150N) and very large contractile motion (over 50%) at very low input pressure (100 kPa). We developed quasi-static analytical models both to characterize the motion and forces and as guidelines for actuator design. Fabrication of FORA mostly involves consumer-grade three-dimensional (3D) printing. We provide a detailed list of materials and dimensions. Fabricated FORAs were tested on a dedicated platform against commercially available pneumatic artificial muscles from Shadow and Festo to showcase its superior performances and validate the analytical models with very good agreements. Finally, a robotic joint was developed driven by two antagonistic FORAs, to showcase the benefits of the performance improvements. With its simple structure, fully characterized mechanism, easy fabrication procedure, and highly desirable performance, FORA could be easily customized to application requirements and fabricated by anyone with access to a 3D printer. This will pave the way to the wider adaptation and application of soft robotic systems.

  2. Actuator with Multi Degrees of Freedom(Actuator)

    OpenAIRE

    矢野, 智昭; Tomoaki, YANO; 産業技術総合研究所

    2006-01-01

    The advantages, problems and the recent developments of the actuator with multi degrees of freedom are presented. At first, the advantages of the actuator with multi degrees of freedom are described. Next, the problems needed to solve for practical use are presented. The recent applications of the actuator with multi degrees of freedom are also reviewed.

  3. Electromechanical response and failure modes of a dielectric elastomer tube actuator with boundary constraints

    International Nuclear Information System (INIS)

    Zhou, Jianyou; Jiang, Liying; Khayat, Roger E

    2014-01-01

    As a widely used configuration for dielectric elastomer (DE) actuators, DE tube actuators (or cylindrical actuators) are also found to be susceptible to electromechanical instability (EMI), which may lead to a premature electrical breakdown (EB), and inhibit the potential actuation of DE actuators. This work investigates the electromechanical response of a DE tube actuator with and without boundary constraints to demonstrate an alternative to avoid EMI while achieving large actuation. Our simulation results based on the Gent strain energy model show that the EMI of a DE tube actuator can be eliminated, and larger actuation deformation can be achieved by applying boundary constraints. As a result of these constraints, consideration is also given to the possible mechanical buckling failure that may occur. Mechanisms of possible failure modes of constrained and unconstrained DE tube actuators, such as electromechanical instability, electrical breakdown and mechanical buckling, are elucidated. This paper should provide better theoretical guidance on how to improve the actuation performance of DE actuators, thus leading to the optimal design of DE-based devices. (paper)

  4. Stiffness Customization and Patterning for Property Modulation of Silicone-Based Soft Pneumatic Actuators.

    Science.gov (United States)

    Sun, Yi; Yap, Hong Kai; Liang, Xinquan; Guo, Jin; Qi, Peng; Ang, Marcelo H; Yeow, Chen-Hua

    2017-09-01

    Soft pneumatic actuators (SPAs), as novel types of motion drivers for robotic devices, excel in many applications, such as rehabilitation and biomimicry, which demand compliance and softness. To further expand their scope of utilization, the SPAs should be customizable to meet the distinctive requirements of different applications. This article proposes a novel perspective on the SPA working mechanism based on stiffness distribution and then presents a versatile method called stiffness customization and patterning (SCP) for SPA body stiffness layout as a novel attempt to customize SPAs with distinctive properties. We fabricated a hybrid type of material combining unstretchable material and silicone with customizable aggregated elasticity. The tensile results showed that embedding unstretchable material directly increases the stiffness of the hybrid material sample, and our stress-strain model for SCP is able to adequately predict the elasticity of hybrid samples with specific material ratios. By applying this approach to bending-type SPAs, we are able to mitigate SPA buckling, a main failure mode of SPAs, and improve the SPA tip force by using hybrid material with globally increased stiffness. We also diversify bending modalities with different stiffness configurations in the hybrid material. SCP offers numerous ways to engineer SPAs for more applications.

  5. Tunable electromechanical actuation in silicone dielectric film

    International Nuclear Information System (INIS)

    Lamberti, Andrea; Di Donato, Marco; Giorgis, Fabrizio; Chiappone, Annalisa; Canavese, Giancarlo

    2014-01-01

    Dielectric elastomer actuator films were fabricated on transparent conductive electrode using bi-component poly(dimethyl)siloxane (PDMS). PDMS is a well-known material in microfluidics and soft lithography for biomedical applications, being easy to process, low cost, biocompatible and transparent. Moreover its mechanical properties can be easily tuned by varying the mixing ratio between the oligomer base and the crosslinking agent. In this work we investigate the chemical composition and the electromechanical properties of PDMS thin film verifying for the first time the tuneable actuation response by simply modifying the amount of the curing agent. We demonstrate that, for a 20:1 ratio of base:crosslinker mixture, a striking 150% enhancement of Maxwell strain occurs at 1 Hz actuating frequency. (paper)

  6. Electrothermally Actuated Microbeams With Varying Stiffness

    KAUST Repository

    Tella, Sherif Adekunle

    2017-11-03

    We present axially loaded clamped-guided microbeams that can be used as resonators and actuators of variable stiffness, actuation, and anchor conditions. The applied axial load is implemented by U-shaped electrothermal actuators stacked at one of the beams edges. These can be configured and wired in various ways, which serve as mechanical stiffness elements that control the operating resonance frequency of the structures and their static displacement. The experimental results have shown considerable increase in the resonance frequency and mid-point deflection of the microbeam upon changing the end conditions of the beam. These results can be promising for applications requiring large deflection and high frequency tunability, such as filters, memory devices, and switches. The experimental results are compared to multi-physics finite-element simulations showing good agreement among them.

  7. Biomimetic actuator and sensor for robot hand

    International Nuclear Information System (INIS)

    Kim, Baekchul; Chung, Jinah; Cho, Hanjoung; Shin, Seunghoon; Lee, Hyoungsuk; Moon, Hyungpil; Choi, Hyouk Ryeol; Koo, Jachoon

    2012-01-01

    To manufacture a robot hand that essentially mimics the functions of a human hand, it is necessary to develop flexible actuators and sensors. In this study, we propose the design, manufacture, and performance verification of flexible actuators and sensors based on Electro Active Polymer (EAP). EAP is fabricated as a type of film, and it moves with changes in the voltage because of contraction and expansion in the polymer film. Furthermore, if a force is applied to an EAP film, its thickness and effective area change, and therefore, the capacitance also changes. By using this mechanism, we produce capacitive actuators and sensors. In this study, we propose an EAP based capacitive sensor and evaluate its use as a robot hand sensor

  8. Biomimetic actuator and sensor for robot hand

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Baekchul; Chung, Jinah; Cho, Hanjoung; Shin, Seunghoon; Lee, Hyoungsuk; Moon, Hyungpil; Choi, Hyouk Ryeol; Koo, Jachoon [Sungkyunkwan Univ., Seoul (Korea, Republic of)

    2012-12-15

    To manufacture a robot hand that essentially mimics the functions of a human hand, it is necessary to develop flexible actuators and sensors. In this study, we propose the design, manufacture, and performance verification of flexible actuators and sensors based on Electro Active Polymer (EAP). EAP is fabricated as a type of film, and it moves with changes in the voltage because of contraction and expansion in the polymer film. Furthermore, if a force is applied to an EAP film, its thickness and effective area change, and therefore, the capacitance also changes. By using this mechanism, we produce capacitive actuators and sensors. In this study, we propose an EAP based capacitive sensor and evaluate its use as a robot hand sensor.

  9. Development of a soft untethered robot using artificial muscle actuators

    Science.gov (United States)

    Cao, Jiawei; Qin, Lei; Lee, Heow Pueh; Zhu, Jian

    2017-04-01

    Soft robots have attracted much interest recently, due to their potential capability to work effectively in unstructured environment. Soft actuators are key components in soft robots. Dielectric elastomer actuators are one class of soft actuators, which can deform in response to voltage. Dielectric elastomer actuators exhibit interesting attributes including large voltage-induced deformation and high energy density. These attributes make dielectric elastomer actuators capable of functioning as artificial muscles for soft robots. It is significant to develop untethered robots, since connecting the cables to external power sources greatly limits the robots' functionalities, especially autonomous movements. In this paper we develop a soft untethered robot based on dielectric elastomer actuators. This robot mainly consists of a deformable robotic body and two paper-based feet. The robotic body is essentially a dielectric elastomer actuator, which can expand or shrink at voltage on or off. In addition, the two feet can achieve adhesion or detachment based on the mechanism of electroadhesion. In general, the entire robotic system can be controlled by electricity or voltage. By optimizing the mechanical design of the robot (the size and weight of electric circuits), we put all these components (such as batteries, voltage amplifiers, control circuits, etc.) onto the robotic feet, and the robot is capable of realizing autonomous movements. Experiments are conducted to study the robot's locomotion. Finite element method is employed to interpret the deformation of dielectric elastomer actuators, and the simulations are qualitatively consistent with the experimental observations.

  10. The Actuated Guitar

    DEFF Research Database (Denmark)

    Larsen, Jeppe Veirum; Overholt, Daniel; Moeslund, Thomas B.

    2013-01-01

    Playing a guitar is normally only for people with fully functional hands. In this work we investigate alternative interaction concepts to enable or re-enable people with non-functional right hands or arms to play a guitar via actuated strumming. The functionality and complexity of right hand...... interaction with the guitar is immense. We therefore divided the right hand techniques into three main areas: Strumming, string picking / skipping, and string muting. This paper explores the first stage, strum- ming. We have developed an exploratory platform called the Actuated Guitar that utilizes a normal...

  11. Fault tolerant linear actuator

    Science.gov (United States)

    Tesar, Delbert

    2004-09-14

    In varying embodiments, the fault tolerant linear actuator of the present invention is a new and improved linear actuator with fault tolerance and positional control that may incorporate velocity summing, force summing, or a combination of the two. In one embodiment, the invention offers a velocity summing arrangement with a differential gear between two prime movers driving a cage, which then drives a linear spindle screw transmission. Other embodiments feature two prime movers driving separate linear spindle screw transmissions, one internal and one external, in a totally concentric and compact integrated module.

  12. Solid electroytes for CNT-based actuators

    Science.gov (United States)

    Riemenschneider, Johannes; Geier, Sebastian; Mahrholz, Thorsten; Mosch, Jürgen; Monner, Hans Peter; Sinapius, Michael

    2009-03-01

    Actuators based on carbon nanotubes (CNT) have the potential to generate high forces at very low voltages. The density of the raw material is just 1330 kg/m3, which makes them well applicable for lightweight applications. Moreover, active strains of up to 1% can be achieved - due to the CNTs dimensional changes on charge injection. Therefore the nanotubes have to be arranged and electrically wired like electrodes of a capacitor. In previous works the system's response of the Nanotubes comprising a liquid electrolyte was studied in detail. The major challenge is to repeat such experiments with solid electrolytes, which is a prerequisite for structural integration. In this paper a method is proposed which makes sure the expansion is not based on thermal expansion. This is done by analysing the electrical system response. As thermal expansion is dominated by ohmic resistance the CNT based actuators show a strong capacitive behavior. This behavior is referable to the constitution of the electrochemical double layer around the nanotubes, which causes the tubes to expand. Also a novel test setup is described, which guarantees that the displacement which is measured will not be caused by bending of a bimorph but due to expansion of a single layer of nanotubes. This paper also presents experimental results demonstrating both, the method of electrical characterization of CNT based actuators with implemented solid electrolytes and the novel test setup which is used to measure the needed data. The actuators which were characterized are hybrids of CNT and the solid electrolyte NAFION which is supplying the ions needed to constitute the electrochemical double layer. The manufacturing, processing of these actuators and also some first experimental results are shown. Unfortunately, the results are not as clear as those for liquid electrolytes, which depend on the hybrid character of the analyzed devices. In the liquid electrolyte based case the CNTs are the only source of

  13. Quantum mechanical/molecular mechanical and docking study of the novel analogues based on hybridization of common pharmacophores as potential anti-breast cancer agents.

    Science.gov (United States)

    Asadi, Parvin; Khodarahmi, Ghadamali; Farrokhpour, Hossein; Hassanzadeh, Farshid; Saghaei, Lotfollah

    2017-06-01

    In an attempt to identify some new potential leads as anti-breast cancer agents, novel hybrid compounds were designed by molecular hybridization approach. These derivatives were structurally derived from hybrid benzofuran-imidazole and quinazolinone derivatives, which had shown good cytotoxicity against the breast cancer cell line (MCF-7). Since aromatase enzyme (CYP19) is highly expressed in the MCF-7 cell line, the binding of these novel hybrid compounds to aromatase was investigated using the docking method. In this study, due to the positive charge on the imidazole ring of the designed ligands and also, the presence of heme iron in the active site of the enzyme, it was decided to optimize the ligand inside the protein to obtain more realistic atomic charges for it. Quantum mechanical/molecular mechanical (QM/MM) method was used to obtain more accurate atomic charges of ligand for docking calculations by considering the polarization effects of CYP19 on ligands. It was observed that the refitted charge improved the binding energy of the docked compounds. Also, the results showed that these novel hybrid compounds were adopted properly within the aromatase binding site, thereby suggesting that they could be potential inhibitors of aromatase. The main binding modes in these complexes were through hydrophobic and H bond interactions showing agreement with the basic physicochemical features of known anti aromatase compounds. Finally, the complex structures obtained from the docking study were used for single point QM/MM calculations to obtain more accurate electronic interaction energy, considering the electronic polarization of the ligand by its protein environment.

  14. Quantum Mechanics/Molecular Mechanics Method Combined with Hybrid All-Atom and Coarse-Grained Model: Theory and Application on Redox Potential Calculations.

    Science.gov (United States)

    Shen, Lin; Yang, Weitao

    2016-04-12

    We developed a new multiresolution method that spans three levels of resolution with quantum mechanical, atomistic molecular mechanical, and coarse-grained models. The resolution-adapted all-atom and coarse-grained water model, in which an all-atom structural description of the entire system is maintained during the simulations, is combined with the ab initio quantum mechanics and molecular mechanics method. We apply this model to calculate the redox potentials of the aqueous ruthenium and iron complexes by using the fractional number of electrons approach and thermodynamic integration simulations. The redox potentials are recovered in excellent accordance with the experimental data. The speed-up of the hybrid all-atom and coarse-grained water model renders it computationally more attractive. The accuracy depends on the hybrid all-atom and coarse-grained water model used in the combined quantum mechanical and molecular mechanical method. We have used another multiresolution model, in which an atomic-level layer of water molecules around redox center is solvated in supramolecular coarse-grained waters for the redox potential calculations. Compared with the experimental data, this alternative multilayer model leads to less accurate results when used with the coarse-grained polarizable MARTINI water or big multipole water model for the coarse-grained layer.

  15. Microstructural, mechanical, and thermal characteristics of recycled cellulose fiber-halloysite-epoxy hybrid nanocomposites

    KAUST Repository

    Alamri, H.; Low, I. M.

    2012-01-01

    Epoxy hybrid-nanocomposites reinforced with recycled cellulose fibers (RCF) and halloysite nanotubes (HNTs) have been fabricated and investigated. The dispersion of HNTs was studied by synchrotron radiation diffraction (SRD) and transmission

  16. Actuating movement in refined wearables

    NARCIS (Netherlands)

    Toeters, M.J.; Feijs, L.M.G.

    2014-01-01

    Nowadays it is quite possible to deploy textiles as sensors and avoid traditional hard sensors. Actuation (movement) turns out more difficult. It is advantageous to combine sensing and actuation, similar to ecological perception theory. Although several actuators are known: SMA, voice coil, motors,

  17. An Assessment of Mechanical and Tribological Property of Hybrid Aluminium Metal Matrix Composite

    Directory of Open Access Journals (Sweden)

    R. Santosh Kumar

    2017-04-01

    Full Text Available Composite materials has huge requirement in the area of automobile, aerospace, and wear resistant applications. This study presents the synthesis of composite reinforced with SiC and Al2O3 using gravity stir casting. Stir casting is the manufacturing process that is incorporated to produce the composite material because of its extreme bonding capacity with base material. The composition of reinforcement with 6061 aluminium matrix is SiC-7.5% and Al2O3 -2.5% respectively. The average size of reinforcement particle is 30-40 microns. The synthesised composite casting is machined using EDM to prepare specimens for various tests. Microstructure study was carried and the microstructure images prove the existence and dispersion of reinforcement particles in the metal matrix. There is no visible porosity is observed. The hardness of the specimen is tested using Vickers hardness tester and found considerable increase when compare with parent alloy Al 6061. Also mechanical and tribological properties of hybrid Aluminium metal matrix composite were employed. The fortifying material, Silicon Carbide is composed of tetrahedral of carbon and silicon atoms with strong bonds in crystal lattice along with its excellent wear resistance property and alumina have high strength and wear resistance. To avoid enormous material wastage and to achieve absolute accuracy, wire-cut EDM process is capitalised to engrave the specimen as per required dimensions. Three Tensile test specimens were prepared, in order to achieve reliability in results as per ASTM- E8 standard, and the values were tabulated. Impact test was carried out and the readings were tabulated. Wear test was carried out using pin on disc wear test apparatus and the results show considerable increase in wear resistant property when compare with parent alloy Al6061.The above work proves the successful fabrication of composite and evaluation of properties.

  18. Miniaturized 3 × 3 array film vibrotactile actuator made with cellulose acetate for virtual reality simulators

    International Nuclear Information System (INIS)

    Ko, Hyun-U; Chan Kim, Hyun; Kim, Jaehwan; Kim, Sang-Youn

    2015-01-01

    This paper reports an array vibrotactile actuator which is suitable for fitting into virtual reality simulators. A 3 × 3 array actuator, of size 15 × 15 × 1 mm 3 , consists of nine cantilever structured cells of which the pillars are supported and made with cellulose acetate by a molding technique. The fabrication process and performance test along with results for the suggested vibrotactile actuator are explained. To simulate the touch force, the top mass is added on the actuator and the actuator performance is measured under actuation. When 2000 V p–p voltage is applied to the actuator, the averaged maximum acceleration for all cells is 0.44 ± 0.19 g, which is above the vibrotactile threshold. The actuation mechanism is associated with the electrostatic force between top and bottom electrodes. (paper)

  19. Coupling between the Output Force and Stiffness in Different Variable Stiffness Actuators

    Directory of Open Access Journals (Sweden)

    Amir Jafari

    2014-08-01

    Full Text Available The fundamental objective in developing variable stiffness actuators is to enable the actuator to deliberately tune its stiffness. This is done through controlling the energy flow extracted from internal power units, i.e., the motors of a variable stiffness actuator (VSA. However, the stiffness may also be unintentionally affected by the external environment, over which, there is no control. This paper analysis the correlation between the external loads, applied to different variable stiffness actuators, and their resultant output stiffness. Different types of variable stiffness actuators have been studied considering springs with different types of nonlinearity. The results provide some insights into how to design the actuator mechanism and nonlinearity of the springs in order to increase the decoupling between the load and stiffness in these actuators. This would significantly widen the application range of a variable stiffness actuator.

  20. Static and dynamic mechanical properties of alkali treated unidirectional continuous Palmyra Palm Leaf Stalk Fiber/jute fiber reinforced hybrid polyester composites

    International Nuclear Information System (INIS)

    Shanmugam, D.; Thiruchitrambalam, M.

    2013-01-01

    Highlights: • New type of hybrid composite with Palmyra Palm Leaf Stalk Fibers (PPLSF) and jute. • Composites fabricated with continuous, unidirectional fibers. • Alkali treatment and hybridizing jute imparted good static and dynamic properties. • Properties are comparable with well know natural/glass fiber composites. • New hybrid composite can be an alternative in place of synthetic fiber composites. - Abstract: Alkali treated continuous Palmyra Palm Leaf Stalk Fiber (PPLSF) and jute fibers were used as reinforcement in unsaturated polyester matrix and their static and dynamic mechanical properties were evaluated. Continuous PPLSF and jute fibers were aligned unidirectionally in bi-layer arrangement and the hybrid composites were fabricated by compression molding process. Positive hybrid effect was observed for the composites due to hybridization. Increasing jute fiber loading showed a considerable increase in tensile and flexural properties of the hybrid composites as compared to treated PPLSF composites. Scanning Electron microscopy (SEM) of the fractured surfaces showed the nature of fiber/matrix interface. The impact strength of the hybrid composites were observed to be less compared to pure PPLSF composites. Addition of jute fibers to PPLSF and alkali treatment of the fibers has enhanced the storage and loss modulus of the hybrid composites. A positive shift of Tan δ peaks to higher temperature and reduction in the peak height of the composites was also observed. The composites with higher jute loading showed maximum damping behavior. Overall the hybridization was found to be efficient showing increased static and dynamic mechanical properties. A comparative study of properties of this hybrid composite with other hybrids made out of using natural/glass fibers is elaborated. Hybridization of alkali treated jute and PPLSF has resulted in enhanced properties which are comparable with other natural/glass fiber composites thus increasing the scope of