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Sample records for cfrp composite aircraft

  1. Structural Diagnostics of CFRP Composite Aircraft Components by Ultrasonic Guided Waves and Built-In Piezoelectric Transducers

    Energy Technology Data Exchange (ETDEWEB)

    Matt, Howard M. [Univ. of California, San Diego, CA (United States)

    2006-01-01

    To monitor in-flight damage and reduce life-cycle costs associated with CFRP composite aircraft, an autonomous built-in structural health monitoring (SHM) system is preferred over conventional maintenance routines and schedules. This thesis investigates the use of ultrasonic guided waves and piezoelectric transducers for the identification and localization of damage/defects occurring within critical components of CFRP composite aircraft wings, mainly the wing skin-to-spar joints. The guided wave approach for structural diagnostics was demonstrated by the dual application of active and passive monitoring techniques. For active interrogation, the guided wave propagation problem was initially studied numerically by a semi-analytical finite element method, which accounts for viscoelastic damping, in order to identify ideal mode-frequency combinations sensitive to damage occurring within CFRP bonded joints. Active guided wave tests across three representative wing skin-to-spar joints at ambient temperature were then conducted using attached Macro Fiber Composite (MFC) transducers. Results from these experiments demonstrate the importance of intelligent feature extraction for improving the sensitivity to damage. To address the widely neglected effects of temperature on guided wave base damage identification, analytical and experimental analyses were performed to characterize the influence of temperature on guided wave signal features. In addition, statistically-robust detection of simulated damage in a CFRP bonded joint was successfully achieved under changing temperature conditions through a dimensionally-low, multivariate statistical outlier analysis. The response of piezoceramic patches and MFC transducers to ultrasonic Rayleigh and Lamb wave fields was analytically derived and experimentally validated. This theory is useful for designing sensors which possess optimal sensitivity toward a given mode-frequency combination or for predicting the frequency dependent

  2. CFRP composites for optics and structures in telescope applications

    Science.gov (United States)

    Romeo, Robert C.

    1995-10-01

    The use of continuous fiber reinforced plastic, CFRP, composite materials is introduced here as a viable material for optical telescopes. The thermal characteristics of CFRPs make them attractive as dimensionally stable materials for all-composite telescope structures and mirrors. Composite mirrors have only recently shown promise as replacements for heavier and more fragile glass mirrors. The areal density of a CFRP mirror can be as much as 10 times less than that of a glass mirror. Optical test results show CFRP composite mirrors can be fabricated with an average surface roughness of less than 10 angstroms. Concept models of scope and CFRP optics with associated figure and roughness data are presented.

  3. NDE and SHM Simulation for CFRP Composites

    Science.gov (United States)

    Leckey, Cara A. C.; Parker, F. Raymond

    2014-01-01

    Ultrasound-based nondestructive evaluation (NDE) is a common technique for damage detection in composite materials. There is a need for advanced NDE that goes beyond damage detection to damage quantification and characterization in order to enable data driven prognostics. The damage types that exist in carbon fiber-reinforced polymer (CFRP) composites include microcracking and delaminations, and can be initiated and grown via impact forces (due to ground vehicles, tool drops, bird strikes, etc), fatigue, and extreme environmental changes. X-ray microfocus computed tomography data, among other methods, have shown that these damage types often result in voids/discontinuities of a complex volumetric shape. The specific damage geometry and location within ply layers affect damage growth. Realistic threedimensional NDE and structural health monitoring (SHM) simulations can aid in the development and optimization of damage quantification and characterization techniques. This paper is an overview of ongoing work towards realistic NDE and SHM simulation tools for composites, and also discusses NASA's need for such simulation tools in aeronautics and spaceflight. The paper describes the development and implementation of a custom ultrasound simulation tool that is used to model ultrasonic wave interaction with realistic 3-dimensional damage in CFRP composites. The custom code uses elastodynamic finite integration technique and is parallelized to run efficiently on computing cluster or multicore machines.

  4. Treatment of CFRP by IAR method and its effect on the fracture behavior of adhesive bonded CFRP/aluminum composites

    International Nuclear Information System (INIS)

    It was shown in the previous studies that adhesive shear strength of carbon fiber reinforced plastics (CFRP) to aluminum composites could be improved by the surface treatment of CFRP using Ar+ ion irradiation. In the present work, the effect of CFRP treatment by Ar+ ion irradiation on the fracture behavior of CFRP/aluminum joint was studied. The aluminum used was 7075-T6 and the CFRP used was multi-directional graphite/epoxy composites whose stacking sequence was [0 deg. /±45 deg. /0 deg. ]3s. The surface of CFRP was treated using Ar+ ion irradiation in an oxygen environment. The Ar+ ion dose used was 1x1016 ions cm-2. Fracture toughness of CFRP/aluminum joint was determined from cracked lap shear specimens using work factor approach. Then, the fracture toughness of ion beam-treated CFRP/aluminum joint was compared with that of untreated CFRP/aluminum joint. The results showed that the fracture toughness of ion beam-treated CFRP/aluminum case was about 72% higher than that of untreated CFRP/aluminum case. X-ray photoelectron spectrometer analysis showed that intensity of hydrophilic bonds, C-O (carbonyl group) and O-C-O (carboxyl group) was increased by the Ar+ ion-irradiation in an oxygen environment. Scanning electron microscope examination showed that cohesive failure occurred for ion beam-treated CFRP/aluminum joint while adhesive failure occurred for untreated CFRP/aluminum joint

  5. One-sided ultrasonic inspection to detect flaws in CFRP composite solid laminates

    Science.gov (United States)

    Im, Kwang-Hee; Zhang, Guilina; Hsu, David K.; Barnard, Dan; Kim, Sun-Kyu; Yang, Yong-Jun; Hwang, Woo-Chae; Yang, In-Young; Park, Je-Woong

    2012-04-01

    The importance of Carbon Fiber reinforced plastics (CFRP) has been generally recognized, and the CFRP composite laminates are widely used. When ultrasonic inspection is applied on actual aircraft components, the part geometry often lacks flat and parallel faces and the benefit of a backwall echo maybe unavailable. So, it is very necessary to detect flaws and defects in the CFRP composite solid laminates due to the flaws of CFRP composite laminates affecting the properties of the laminate. Firstly, we used miniature potted angle beam transducers (designed for generating mode-converted shear waves or Rayleigh waves in steel) on solid laminates of composites. A pair of such transducers was mounted in a holder in a nose-to-nose fashion to be used as a scanning probe on composites. Secondly, a method was utilized to determine the porosity content of a composite lay-up by processing micrograph images of the laminate. The results from the image processing method are compared with existing data. C-scan images of CFRP samples, which were based on the impacted samples were then produced by combining the pitch-catch probe with a portable manual scanner known as the Generic Scanner ("GenScan"). The signal amplitude of pitch-catch C-scan images was also correlated to the volume percent of porosity in carbon composite laminates. Finally, a simulation was performed with the numerical Wave-2000 Code for predicting the ultrasonic wave in the sample.

  6. Commercial aircraft composite technology

    CERN Document Server

    Breuer, Ulf Paul

    2016-01-01

    This book is based on lectures held at the faculty of mechanical engineering at the Technical University of Kaiserslautern. The focus is on the central theme of societies overall aircraft requirements to specific material requirements and highlights the most important advantages and challenges of carbon fiber reinforced plastics (CFRP) compared to conventional materials. As it is fundamental to decide on the right material at the right place early on the main activities and milestones of the development and certification process and the systematic of defining clear requirements are discussed. The process of material qualification - verifying material requirements is explained in detail. All state-of-the-art composite manufacturing technologies are described, including changes and complemented by examples, and their improvement potential for future applications is discussed. Tangible case studies of high lift and wing structures emphasize the specific advantages and challenges of composite technology. Finally,...

  7. STUDY ON DRILLING CHARACTERISTICS AND MECHANICAL PROPERTIES OF CFRP COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Seung-Chul Lee; Seong-Taek Jeong; Jong-Nam Park; Sun-Jin Kim; Gyu-Jae Cho

    2008-01-01

    Stacking plates of CFRP composite materials are increasingly used because of their unique characteristics.However,unlike other materials used in metallurgy they have a disadvan tage of uneven quality and anisotropy when combined with other composites.Hence,specimens of CFRP stacking plates are manufactured by changing orientation angles throughout three quasi isotropic plies (0°/45°/90°/-45°)6s (03°/453°/903°/-453°)2s,and (06°/456°/906°/- 456°)s and In this study 3-point bending tests and transverse bending tests have been carried out in order to find out mechanical characteristics according to orientation angles by stacking in 6 different types along with the change of stacking composition method of a CFRP composite.

  8. TEA CO2 laser machining of CFRP composite

    Science.gov (United States)

    Salama, A.; Li, L.; Mativenga, P.; Whitehead, D.

    2016-05-01

    Carbon fibre-reinforced polymer (CFRP) composites have found wide applications in the aerospace, marine, sports and automotive industries owing to their lightweight and acceptable mechanical properties compared to the commonly used metallic materials. Machining of CFRP composites using lasers can be challenging due to inhomogeneity in the material properties and structures, which can lead to thermal damages during laser processing. In the previous studies, Nd:YAG, diode-pumped solid-state, CO2 (continuous wave), disc and fibre lasers were used in cutting CFRP composites and the control of damages such as the size of heat-affected zones (HAZs) remains a challenge. In this paper, a short-pulsed (8 μs) transversely excited atmospheric pressure CO2 laser was used, for the first time, to machine CFRP composites. The laser has high peak powers (up to 250 kW) and excellent absorption by both the carbon fibre and the epoxy binder. Design of experiment and statistical modelling, based on response surface methodology, was used to understand the interactions between the process parameters such as laser fluence, repetition rate and cutting speed and their effects on the cut quality characteristics including size of HAZ, machining depth and material removal rate (MRR). Based on this study, process parameter optimization was carried out to minimize the HAZ and maximize the MRR. A discussion is given on the potential applications and comparisons to other lasers in machining CFRP.

  9. Bond Strength of Composite CFRP Reinforcing Bars in Timber

    Directory of Open Access Journals (Sweden)

    Marco Corradi

    2015-07-01

    Full Text Available The use of near-surface mounted (NSM fibre-reinforced polymer (FRP bars is an interesting method for increasing the shear and flexural strength of existing timber members. This article examines the behaviour of carbon FRP (CFRP bars in timber under direct pull-out conditions. The objective of this experimental program is to investigate the bond strength between composite bars and timber: bars were epoxied into small notches made into chestnut and fir wood members using a commercially-available epoxy system. Bonded lengths varied from 150 to 300 mm. Failure modes, stress and strain distributions and the bond strength of CFRP bars have been evaluated and discussed. The pull-out capacity in NSM CFRP bars at the onset of debonding increased with bonded length up to a length of 250 mm. While CFRP bar’s pull-out was achieved only for specimens with bonded lengths of 150 and 200 mm, bar tensile failure was mainly recorded for bonded lengths of 250 and 300 mm.

  10. Rotary ultrasonic machining of CFRP composites: a study on power consumption.

    Science.gov (United States)

    Cong, W L; Pei, Z J; Deines, T W; Srivastava, Anil; Riley, L; Treadwell, C

    2012-12-01

    Carbon fiber reinforced plastic (CFRP) composites are very difficult to machine. A large number of holes need to be drilled in CFRP for many applications. Therefore, it is important to develop cost-effective drilling processes. CFRP has been drilled by rotary ultrasonic machining (RUM) successfully. The literature has reports about the effects of input variables on output variables (including cutting force, torque, surface roughness, tool wear, and workpiece delamination) in RUM of CFRP. However, there are no reports on power consumption in RUM of CFRP. This paper reports the first study on power consumption in RUM of CFRP. It reports an experimental investigation on effects of input variables (ultrasonic power, tool rotation speed, feedrate, and type of CFRP) on power consumption of each component (including ultrasonic power supply, spindle motor, coolant pump, and air compressor) and the entire RUM system.

  11. Rotary ultrasonic machining of CFRP composites: a study on power consumption.

    Science.gov (United States)

    Cong, W L; Pei, Z J; Deines, T W; Srivastava, Anil; Riley, L; Treadwell, C

    2012-12-01

    Carbon fiber reinforced plastic (CFRP) composites are very difficult to machine. A large number of holes need to be drilled in CFRP for many applications. Therefore, it is important to develop cost-effective drilling processes. CFRP has been drilled by rotary ultrasonic machining (RUM) successfully. The literature has reports about the effects of input variables on output variables (including cutting force, torque, surface roughness, tool wear, and workpiece delamination) in RUM of CFRP. However, there are no reports on power consumption in RUM of CFRP. This paper reports the first study on power consumption in RUM of CFRP. It reports an experimental investigation on effects of input variables (ultrasonic power, tool rotation speed, feedrate, and type of CFRP) on power consumption of each component (including ultrasonic power supply, spindle motor, coolant pump, and air compressor) and the entire RUM system. PMID:22986155

  12. Strengthening of steel–concrete composite girders using carbon fibre reinforced polymer (CFRP) plates

    Indian Academy of Sciences (India)

    S M Mosavi; A Sadeghi Nik

    2015-02-01

    Applying composites in order to strengthen and renew the infrastructures has globally been accepted. Traditional methods to strengthen the out-of-standard structures are costly, time consuming and requires a lot of labour. Today, new techniques are hired using light and strong substances which also resist against corrosion, known as Carbon Fibre Reinforced Polymer (CFRP) plates. Regarding the high tensile strength and proper module of elasticity, CFRP plates are considered as a suitable alternative to strengthen girders. The behaviour of steel–concrete composite girders being statically loaded and strengthened by CFRP plates in this study. The CFRP plates used in this study have been stuck, with epoxy adhesive, under the tensile sections of three steel girders. The results accompanied with analytical study of moment–curvature and numerical analysis done with ANSYS, show that CFRP plates with epoxy adhesive increases the ultimate loading capacity of steel–concrete composite girder. Plastic stiffness of the girders was also increased.

  13. Ultrasonic Approach of Rayleigh Pitch-Catch Contact Ultrasound Waves on CFRP Laminated Composites

    Institute of Scientific and Technical Information of China (English)

    In-Young Yang; Kwang-Hee Im; Uk Heo; David K Hsu; Je-Woong Park; Hak-Joon Kim; Sung-Jin Song

    2008-01-01

    CFRP (carbon fiber reinforced plastics) composite materials have wide applicability because of their inherent design flexibility and improved material properties. However, impacted composite structures have 50%-75% less strength than undamaged structures. In this work, a CFRP composite material was nondestructively characterized in order to ensure product quality and structural integrity of CFRP and one-sided pitch-catch technique was developed to measure impacted-damaged area by using an automated-data acquisition system in an immersion tank. A pitch-catch signal was found to be more sensitive than normal incidence backwall echo of longitudinal wave under defect conditions in the composite.

  14. Development of composite aircraft components in INCDT COMOTI, Bucharest

    Directory of Open Access Journals (Sweden)

    Raluca VOICU

    2012-12-01

    Full Text Available This paper presents the recent research activities within INCDT COMOTI, in the composite materials field. The author makes a short introduction of this field and presents an example of application developed within the composite materials laboratory from INCDT COMOTI, targeting the aeronautic field. The aircraft component is a stator blade made of CFRP composites, integrating new active noise reduction technologies and manufactured by means of the autoclave technology.

  15. Effects of CFRP Strengthening on Dynamic and Fatigue Responses of Composite Bridge

    Directory of Open Access Journals (Sweden)

    Kittisak Kuntiyawichai

    2014-01-01

    Full Text Available This paper investigates the effect of CFRP strengthening on dynamic and fatigue responses of composite bridge using finite element program ABAQUS. Dynamic and fatigue responses of composite bridge due to truck load based on AASHTO standard are investigated. Two types of CFRP strengthening techniques, CFRP sheets and CFRP deck, are applied to both the damaged and undamaged bridges. For the case of damaged bridge, two through-thickness crack sizes, 3 mm and 6 mm in depth, are assumed at midspan of the steel girders. Furthermore, effects of the number of steel girders on the dynamic and fatigue responses are also considered. The results show that the maximum responses of composite bridges occur for dual lane cases. By using CFRP as a strengthening material, the maximum stress and deflection of the steel girders reduce and consequently increase the fatigue life of the girders. After introducing initial crack into the steel girders of the composite bridges, the fatigue life of the bridges is dramatically reduced. However, the overall performance of the damaged composite bridge can be improved by using CFRP, albeit with less effectiveness. Therefore, if cracks are found, steel welding must be performed before strengthening the composite bridge by CFRP.

  16. Nonlinear finite element analysis of mechanical characteristics on CFRP composite pressure vessels

    International Nuclear Information System (INIS)

    CFRP(Carbon Fibre Reinforced Plastic) composite pressure vessel was calculated using finite element program of ANSYS for their mechanical characteristics in this paper. The elastic-plastic model and elements of Solid95 were selected for aluminium alloys of gas cylinder. Also liner-elastic model and layer elements of Shell99 were adopted for carbon fibre/epoxy resin. The stress state of CFRP composite pressure vessel was calculated under different internal pressures include pre-stressing pressures, working pressures, test hydraulic pressures, minimum destructive pressures etcetera to determine the size of gas cylinder and layer parameter of carbon fibre. The mechanical characteristics CFRP composite vessel could were using to design and test of gas cylinder. Numerical results showed that finite element model and calculating method were efficient for study of CFRP gas cylinder and useful for engineering design.

  17. Finite element analysis when orthogonal cutting of hybrid composite CFRP/Ti

    Science.gov (United States)

    Xu, Jinyang; El Mansori, Mohamed

    2015-07-01

    Hybrid composite, especially CFRP/Ti stack, is usually considered as an innovative structural configuration for manufacturing the key load-bearing components in modern aerospace industry. This paper originally proposed an FE model to simulate the total chip formation process dominated the hybrid cutting operation. The hybrid composite model was established based on three physical constituents, i.e., Ti constituent, interface and CFRP constituent. Different constitutive models and damage criteria were introduced to replicate the interrelated cutting behaviour of the stack material. The CFRP/Ti interface was modelled as a third phase through the concept of cohesive zone (CZ). Particular attention was made on the comparative studies of the influence of different cutting-sequence strategies on the machining responses induced in hybrid stack cutting. The numerical results emphasized the pivotal role of cutting-sequence strategy on the various machining induced responses including cutting-force generation, machined surface quality and induced interface damage.

  18. Application of Desalination with CFRP Composite Electrode to Concrete Deteriorated by Chloride Attack

    Science.gov (United States)

    Yamaguchi, Keisuke; Ueda, Takao; Nanasawa, Akira

    As a new rehabilitation technique for recovery both of loading ability and durability of concrete structures deteriorated by chloride attack, desalination (electrochemical chloride removal technique from concrete) using CFRP composite electrode bonding to concrete has been developed. In this study, basic application was tried using small RC specimens, and also application to the large-scale RC beams deteriorated by the chloride attack through the long-term exposure in the outdoors was investigated. As the result of bending test of treated specimens, the decrease of strengthening effect with the electrochemical treatment was observed in the case of small specimens using low absorption rate resin for bonding, on the other hand, in the case of large-scale RC beam using 20% absorption rate resin for bonding CFRP composite electrode, enough strengthening effect was obtained by the bending failure of RC beam with the fracture of CFRP board.

  19. Potential emissions savings of lightweight composite aircraft components evaluated through life cycle assessment

    Directory of Open Access Journals (Sweden)

    2011-03-01

    Full Text Available A cradle-to-grave life cycle assessment (LCA of structural aircraft materials has been utilised to assess and compare the total emissions produced during manufacturing, use and disposal of aerospace materials and their selected components. First, a comparison of aluminium, GLARE and carbon fibre reinforced polymer (CFRP plates was performed to investigate the potential of lightweight composites in reducing aviation emissions. Subsequently, a case study is presented on a tubular component for which more accurate manufacturing data were directly available. A structural steel tube was replaced with a composite tubular component. The analysis has shown that once the composite material is used as a component in the aircraft, there is a cumulative saving of aircraft fuel and emissions, in particular from CFRP structures. The environmental analysis included the long-term use predictions for CFRPs, involving detailed raw materials production, use and operation, and disposal scenarios.

  20. ADHESIVE WEAR PERFORMANCE OF CFRP MULTILAYERED POLYESTER COMPOSITES UNDER DRY/WET CONTACT CONDITIONS

    OpenAIRE

    D. DANAELAN; B. F. YOUSIF

    2008-01-01

    The tribo-performance of a new engineering composite material based on coconut fibers was investigated. In this work, coconut fibers reinforced polyester (CFRP) composites were developed. The tribo-experiments were conducted by using pin-on-disc machine under dry and wet sliding contact condition against smooth stainless steel counterface. Worn surfaces were observed using optical microscope. Friction coefficient and specific wear rate were presented as a function of sliding distance (0–0.6 k...

  1. Pursing Contamination Detection on Aircraft CFRP Surfaces By Artificial Olfaction Techniques

    Science.gov (United States)

    De Vito, Saverio; Massera, Ettore; Fattoruso, Grazia; Miglietta, Maria Lucia; Di Francia, Girolamo

    2011-09-01

    Carbon Fiber Reinforced Polymer (CFRP) structures can be easily bonded via adhesive assembly procedures but their cleanliness is of fundamental importance to ensure the strength of the adhesive bonding. Actually, surface contamination by several aeronautics fluids eventually results in weak or kissing bonds. The goal of our research work is to investigate solid state chemical sensors and artificial olfaction techniques (AO) for the detection of CFRP surface contamination by aeronautic fluids. This result will allow the implementation of an instrumental NDT procedure for CFRP surface cleanliness assessment prior to bonding. Herein, results of our first experimental setup, based on the use of an array of polymer sensors for the detection of aeronautic fluids contamination, are presented.

  2. High-power picosecond laser drilling/machining of carbon fibre-reinforced polymer (CFRP) composites

    Science.gov (United States)

    Salama, A.; Li, L.; Mativenga, P.; Sabli, A.

    2016-02-01

    The large differences in physical and thermal properties of the carbon fibre-reinforced polymer (CFRP) composite constituents make laser machining of this material challenging. An extended heat-affected zone (HAZ) often occurs. The availability of ultrashort laser pulse sources such as picosecond lasers makes it possible to improve the laser machining quality of these materials. This paper reports an investigation on the drilling and machining of CFRP composites using a state-of-the-art 400 W picosecond laser system. Small HAZs (drilled on sample of 6 mm thickness, whereas no HAZ was seen below the top surface on the cut surfaces. Multiple ring material removal strategy was used. Furthermore, the effect of laser processing parameters such as laser power, scanning speed and repetition rate on HAZ sizes and ablation depth was investigated.

  3. Effects of the shock duration on the response of CFRP composite laminates

    International Nuclear Information System (INIS)

    Shock loads induce a local tensile stress within a sample. The location and amplitude of this high strain rate stress can be monitored respectively by the duration and intensity of the shock. The process is applied to carbon fibre reinforced polymer (CFRP) composites, involved in aeronautic or defense industry. This paper describes the response of CFRP laminates of different thicknesses to a shock load normal to the fibres direction. The effects of the shock duration on the wave propagation are key issues of this work. Experiments have been performed on high power laser facilities and on a high power pulsed generator to get a wide range of pulse duration from fs to µs. Numerical simulation provides a comprehensive approach of the wave propagation and tensile stress generation within these complex materials. The main result concerns the relation between the load duration, the tensile stress and the induced delamination within 1, 4 and 8 ply composite laminates. (paper)

  4. Detection of Fiber Layer-Up Lamination Order of CFRP Composite Using Thermal-Wave Radar Imaging

    Science.gov (United States)

    Wang, Fei; Liu, Junyan; Liu, Yang; Wang, Yang; Gong, Jinlong

    2016-09-01

    In this paper, thermal-wave radar imaging (TWRI) is used as a nondestructive inspection method to evaluate carbon-fiber-reinforced-polymer (CFRP) composite. An inverse methodology that combines TWRI with numerical optimization technique is proposed to determine the fiber layer-up lamination sequences of anisotropic CFRP composite. A 7-layer CFRP laminate [0°/45°/90°/0°]_{{s}} is heated by a chirp-modulated Gaussian laser beam, and then finite element method (FEM) is employed to calculate the temperature field of CFRP laminates. The phase based on lock-in correlation between reference chirp signal and the thermal-wave signal is performed to obtain the phase image of TWRI, and the least square method is applied to reconstruct the cost function that minimizes the square of the difference between the phase of TWRI inspection and numerical calculation. A hybrid algorithm that combines the simulation annealing with Nelder-Mead simplex research method is employed to solve the reconstructed cost function and find the global optimal solution of the layer-up sequences of CFRP composite. The result shows the feasibility of estimating the fiber layer-up lamination sequences of CFRP composite with optimal discrete and constraint conditions.

  5. Rotary ultrasonic machining of CFRP: A comparison with grinding.

    Science.gov (United States)

    Ning, F D; Cong, W L; Pei, Z J; Treadwell, C

    2016-03-01

    Carbon fiber reinforced plastic (CFRP) composites have been intensively used in various industries due to their superior properties. In aircraft and aerospace industry, a large number of holes are required to be drilled into CFRP components at final stage for aircraft assembling. There are two major types of methods for hole making of CFRP composites in industry, twist drilling and its derived multi-points machining methods, and grinding and its related methods. The first type of methods are commonly used in hole making of CFRP composites. However, in recent years, rotary ultrasonic machining (RUM), a hybrid machining process combining ultrasonic machining and grinding, has also been successfully used in drilling of CFRP composites. It has been shown that RUM is superior to twist drilling in many aspects. However, there are no reported investigations on comparisons between RUM and grinding in drilling of CFRP. In this paper, these two drilling methods are compared in five aspects, including cutting force, torque, surface roughness, hole diameter, and material removal rate.

  6. Rotary ultrasonic machining of CFRP: A comparison with grinding.

    Science.gov (United States)

    Ning, F D; Cong, W L; Pei, Z J; Treadwell, C

    2016-03-01

    Carbon fiber reinforced plastic (CFRP) composites have been intensively used in various industries due to their superior properties. In aircraft and aerospace industry, a large number of holes are required to be drilled into CFRP components at final stage for aircraft assembling. There are two major types of methods for hole making of CFRP composites in industry, twist drilling and its derived multi-points machining methods, and grinding and its related methods. The first type of methods are commonly used in hole making of CFRP composites. However, in recent years, rotary ultrasonic machining (RUM), a hybrid machining process combining ultrasonic machining and grinding, has also been successfully used in drilling of CFRP composites. It has been shown that RUM is superior to twist drilling in many aspects. However, there are no reported investigations on comparisons between RUM and grinding in drilling of CFRP. In this paper, these two drilling methods are compared in five aspects, including cutting force, torque, surface roughness, hole diameter, and material removal rate. PMID:26614168

  7. Composite components on commercial aircraft

    Science.gov (United States)

    Dexter, H. B.

    1980-01-01

    The paper considers the use of composite components in commercial aircraft. NASA has been active in sponsoring flight service programs with advanced composites for the last 10 years, with 2.5 million total composite component hours accumulated since 1970 on commercial transports and helicopters with no significant degradation in residual strength of composite components. Design, inspection, and maintenance procedures have been developed; a major NASA/US industry technology program has been developed to reduce fuel consumption of commercial transport aircraft through the use of advanced composites.

  8. Cutting Modeling of Hybrid CFRP/Ti Composite with Induced Damage Analysis

    Directory of Open Access Journals (Sweden)

    Jinyang Xu

    2016-01-01

    Full Text Available In hybrid carbon fiber reinforced polymer (CFRP/Ti machining, the bi-material interface is the weakest region vulnerable to severe damage formation when the tool cutting from one phase to another phase and vice versa. The interface delamination as well as the composite-phase damage is the most serious failure dominating the bi-material machining. In this paper, an original finite element (FE model was developed to inspect the key mechanisms governing the induced damage formation when cutting this multi-phase material. The hybrid composite model was constructed by establishing three disparate physical constituents, i.e., the Ti phase, the interface, and the CFRP phase. Different constitutive laws and damage criteria were implemented to build up the entire cutting behavior of the bi-material system. The developed orthogonal cutting (OC model aims to characterize the dynamic mechanisms of interface delamination formation and the affected interface zone (AIZ. Special focus was made on the quantitative analyses of the parametric effects on the interface delamination and composite-phase damage. The numerical results highlighted the pivotal role of AIZ in affecting the formation of interface delamination, and the significant impacts of feed rate and cutting speed on delamination extent and fiber/matrix failure.

  9. Influence of Interface Strength on Bending Properties of CFRP-Concrete Composite Beam%界面强度对CFRP-混凝土组合梁弯曲性能的影响

    Institute of Scientific and Technical Information of China (English)

    杨文龙; 张亚芳; 刘浩; 蔡北海

    2012-01-01

    CFRP(Carbon Fiber Reinforced Polymer)与混凝土之间的界面黏贴强度是影响CFRP-混凝上组合梁弯曲性能的一个重要因素.文中按CFRP布的黏结长度不同建立了3组不同界面强度的数值模型.模拟了采用位移控制梁的四点弯曲加载过程,分析了界面强度对CFRP-混凝土组合梁宏观弯曲性能的影响.结果表明:界面强度对组合梁的宏观承载力与开裂前刚度影响甚微;但对梁开裂后的刚度与延性影响较大;黏结长度越长,CFRP-混凝土组合梁对界面强度变化的敏感性越大.%The interfacial bond strength between CFRP (carbon fiber polymer) and concrete is an important factor for bending properties of CFRP-concrete composite beam. Three groups of numerical models are established based on the different bond length and interfacial strength . Four-point bending loading processes controlled by displacement are simulated. Influence of Interface Strength on Bending Properties of CFRP-concrete beam has been discussed. The results show that the interface strength has little effect on the macro-bearing capacity and the stiffness of composite beams pre-cracking, but significant effect on stiffness and ductility after cracking, and it also reflected that the longer CFRP is stuck, the more sensitive to the changes of the interfacial strength.

  10. CFRP composite optical telescope assembly for the 1 m ULTRA project

    Science.gov (United States)

    Martin, Robert N.; Romeo, Robert C.

    2006-06-01

    The focus of the ULTRA Project is to develop and test Ultra-Lightweight Technology for Research applications in Astronomy. The ULTRA project is a collaborative effort involving the private firm Composite Mirror Applications, Inc (CMA) and 3 universities: University of Kansas, San Diego State University, and Dartmouth College. Funding for ULTRA is predominately from a NSF three year MRI program grant to CMA and KU with additional support from CMA, KU and SDSU. The goal of the ULTRA program is to demonstrate that a viable alternative exists to traditional glass mirror and steel telescope technology by designing, fabricating and testing a research telescope constructed from carbon fiber reinforced plastic (CFRP) materials. In particular, a 1m diameter, Cassegrain telescope optics set and optical tube assembly (OTA) are being designed and fabricated by CMA. The completed telescope will be deployed at SDSU's Mt Laguna Observatory in a refurbished structure (new dome and mount provided via KU and SDSU). We expect that a successful completion and testing of this project will lead to future use of CFRP technology in larger telescopes and segmented telescopes. This paper describes the OTA (optical tube assembly) that has been developed for the ULTRA project. The mirror technology is described in another paper in this conference. A poster describes the ULTRA project overview in more detail.

  11. Adhesive Wear Performance of CFRP Multilayered Polyester Composites Under Dry/wet Contact Conditions

    Science.gov (United States)

    Danaelan, D.; Yousif, B. F.

    The tribo-performance of a new engineering composite material based on coconut fibers was investigated. In this work, coconut fibers reinforced polyester (CFRP) composites were developed. The tribo-experiments were conducted by using pin-on-disc machine under dry and wet sliding contact condition against smooth stainless steel counterface. Worn surfaces were observed using optical microscope. Friction coefficient and specific wear rate were presented as a function of sliding distance (0-0.6 km) at different sliding velocities (0.1-0.28 m/s). The effect of applied load and sliding velocity was evaluated. The results showed that all test parameters have significant influence on friction and wear characteristics of the composites. Moreover, friction coefficient increased as the normal load and speed increased, the values were about 0.7-0.9 under dry contact condition. Meanwhile, under wet contact condition, there was a great reduction in the friction coefficient, i.e. the values were about 0.1-0.2. Furthermore, the specific wear rates were found to be around 2-4 (10-3) mm3/Nm under dry contact condition and highly reduced under wet condition. In other words, the presence of water as cleaner and polisher assisted to enhance the adhesive wear performance of CFRP by about 10%. The images from optical microscope showed evidence of adhesive wear mode with transition to abrasive wear mode at higher sliding velocities due to third body abrasion. On the other hand, optical images for wet condition showed less adhesive wear and smooth surfaces.

  12. Remote Strain Sensing of CFRP Using Microwave Frequency Domain Reflectometry

    Science.gov (United States)

    Wilson, William C.; Moore, Jason P.; Juarez, Peter D.

    2016-01-01

    NASA's Advanced Composites Project is investigating technologies that increase automated remote inspection of aircraft composite structures. Therefore, microwave Frequency Domain Reflectometry (FDR) is being investigated as a method of enabling rapid remote measurement of strain occurring at the first ply of a composite fiber reinforced polymer (CFRP) structure using Radio Frequency (RF) Electro-Magnetic (EM) radiation. While microwave reflectometry has been used to detect disbonds in CFRP structures, its use in detecting strain has been limited. This work will present data demonstrating the measurement of the reactance changes due to loading conditions that are indicative of strain in a CFRP structure. In addition, the basic EM signature will be presented along with an analysis of temperature and humidity effects.

  13. Detection of stacking orientation error of CFRP composite laminates using ultrasound waves

    Institute of Scientific and Technical Information of China (English)

    Sun-Kyu KIM; David HSU; Young-Hwan SEO; Kwang-Hee IM

    2009-01-01

    A jig was developed for generating a shear wave. A pyramid with an isosceles triangle with two 45° was made of aluminum to generate shear waves using two longitudinal transducers based on ultrasonic-polarized mechanism. Also, the signal splitter was connected to the pulser jack on the pulser/receiver and to the longitudinal transducers. Therefore, an experimental way was performed in order to make shear wave on the bottom of aluminum alloyed pyramid. Also, a jig was manufactured and developed for generating a shear wave based on the computer numerical simulation. It is found that the experimentally shear wave variation of newly-designed jig is consistent with computer numerical simulation results and shear wave ultrasonic application can be very useful to detect the defects in CFRP composites.

  14. ULTRASONIC INFLUENCE OF POROSITY LEVEL ON CFRP COMPOSITE LAMINATES USING RAYLEIGH PROBE WAVES

    Institute of Scientific and Technical Information of China (English)

    Je-Woong Park; Do-Jung Kim; Kwang-Hee Im; Sang-Kyu Park; David K.Hsu; Adam H.Kite; Sun-Kyu Kim; Kil-Sung Lee; In-Young Yang

    2008-01-01

    It was found that a pitch-catch signal was more sensitive than normal incidence backwall echo of longitudinal wave to subtle flaw conditions in the composites (damages,fiber orientation,low level porosity,ply waviness,and cracks).Both the strength and stiffness depend on the fiber orientation and porosity volume in the composites.The porosity content of a composite structure is critical to the strength and performance of the structure in general.The depth of the sampling volume where the pitch-catch signal came from was relatively shallow with the head to-head miniature Rayleigh probes,but the depth can be increased by increasing the separation distance of the transmitting and receiving probes.Also,a method was utilized to determine the porosity content of a composite lay-up by processing micrograph images of the laminate.A free software package was utilized to process micrograph images of the test sample.The results from the image processing method were compared with existing data.Beam profile was characterized in unidirectional CFRP(carbon fiber reinforced plastics) using pitch-catch Rayleigh probes and the one-sided pitch-catch technique was utilized to produce C-scan images with the aid of the automatic scanner.

  15. Effect of tubing material on conventional and thin FBG sensor for embedded environment impact monitoring of CFRP composites

    Science.gov (United States)

    Park, Yurim; Shrestha, Pratik; Kwon, Hyunseok; Kim, Jin-Hyuk; Kwon, Heejung; Kim, Chun-Gon

    2016-04-01

    Applications of composite materials in aerospace structures is increasing due to the outstanding properties, however, monitoring such composite structures exposed to harsh environments is still a posing issue. Low Earth orbit space structures are exposed to property degradation and damage from high-degree vacuum, ultraviolet radiation, thermal cycling, and atomic oxygen attack which are detrimental to composite materials. In this study, FBG sensors for embedding in CFRP composite plates in different thickness locations to provide health and damage monitoring of the material exposed to such environments regarding the overall health of the material with a focus on the exposed surface are explored in comparison to conventional FBG sensors.

  16. DELAMINATION PREDICTION IN DRILLING OF CFRP COMPOSITES USING ARTIFICIAL NEURAL NETWORK

    Directory of Open Access Journals (Sweden)

    K. PALANIKUMAR

    2011-04-01

    Full Text Available Carbon fibre reinforced plastic (CFRP materials play a major role in the applications of aeronautic, aerospace, sporting and transportation industries. Machining is indispensible and hence drilling of CFRP materials is considered in this present study with respect to spindle speed in rpm, drill size in mm and feed in mm/min. Delamination is one of the major defects to be dealt with. The experiments are carried out using computer numerical control machine and the results are applied to an artificial neural network (ANN for the prediction of delamination factor at the exit plane of the CFRP material. It is found that ANN model predicts the delamination for any given set of machining parameters with a maximum error of 0.81% and a minimum error of 0.03%. Thus an ANN model is highly suitable for the prediction of delamination in CFRP materials.

  17. Measurement of Temperature and Residual Strain during Fatigue of a CFRP Composite Using Fiber Bragg Grating Sensors

    Institute of Scientific and Technical Information of China (English)

    SHEN Xiaoyan; LIN Yuchi; WANG Wei

    2009-01-01

    Fatigue behaviour has important implications for engineering composite structures in sectors ranging from automotive to aerospace. Optical sensing technology displays excellent performance in these fields for monitoring. In this paper, temperature and residual strain during fatigue of a carbon fiber reinforced polymer(CFRP) are investigated. Four autoclaved CFRP beam specimens, with fiber Bragg grating(FBG) sensors and thermocouples embedded at selected locations, are subjected to three-point bending cyclic loading on the BOSE testing machine for fatigue testing. Thermocouples are used to measure the temperature while FBGs can sense the temperature and strain as well. Seven tests in total are conducted at different frequencies, and each test lasts for several days. From the experimental results, transient steep peaks of temperature increases (up to 2.3 ℃) are discovered at the beginning of the load. The following constant temperature increments are around 1.0 ℃, which is not relevant to frequencies from 0.1 Hz to 20 Hz and suspected due to fatigue. Residual strains of 1×10-5-2×10-5 during fatigue, fading away rapidly when unloading, are also reported. Embedded FBGs here are validated to sense temperature and strains in composite structures, which demonstrates promising potentials in structure monitoring fields. CFRP are verified to have an excellent performance during fatigue with low temperature increase and residual strain.

  18. Optimisation of the rivet joints of the CFRP composite material and aluminium alloy

    Directory of Open Access Journals (Sweden)

    A. Czulak

    2007-01-01

    Full Text Available Purpose: The project included analysis of strain, cracking, and failure of riveted joints of plate elements madefrom the carbon-fibre-reinforced plastics (CFRP and from the 6061 aluminium alloy.Design/methodology/approach: The modelled static tensile strength test carried out for the plates from CFRPand from the 6061 aluminium alloy joined with the steel rivet. Computer simulation was carried out with IDEASsoftware package employing the FEM.Findings: Simulations using the mesh with a bigger number of FEM elements do not yield better accuracy ofcalculations and do not improve convergence with the results of laboratory experiments. Only the calculationtime gets longer. Computer simulation has also show that the type of contacts employed between elementsaffects the results significantly.Research limitations/implications: For the composite materials, joints between materials and computersimulation examinations are planed.Practical implications: Results obtained for the mesh with 4 and 5 FEM elements are the closest to the resultsof laboratory experiments, which is confirmed by the strain plot. Simulations using the mesh with a biggernumber of FEM elements do not yield better accuracy of calculations and do not improve convergence with theresults of laboratory experiments. Only the calculation time gets longer. Computer simulation has show that thetype of contacts employed between elements affects the results significantly.Originality/value: The paper presents influence of fibre mesh closeness on convergence of the results with laboratorytests. Simulation results were collected and compared with the laboratory static tensile strength tests results.

  19. Three-dimensional reconstruction of fracture surfaces of CFRP type composite materials; Reconstrucao tridimensional de superficies de fratura de materias compositos do tipo CFRP

    Energy Technology Data Exchange (ETDEWEB)

    Lobo, Raquel de Moraes

    2009-07-01

    The three-dimensional reconstruction of fracture surfaces of CFRP type composite materials is presented in this work as a possible method for the fractographic analysis of this material, whose rupture surface can present an accentuated roughness, with great variation in height. Two methods are presented for this purpose: the reconstruction for variable focus, carried through with images of optic microscopy and the reconstruction for parallax, carried through with pair of stereo images, obtained by means of scanning electronic microscopy. An evaluation is carried through for each one of the two methods, having argued its limits and the efficiency of each one of them, before the difficulties of analysis of unidirectional and multidirectional composite materials. The method of variable focus presented an excellent reconstruction result, but it has the need of a great number of images, spent time of the instrument and magnifying limit of the images as factors to be considered in the choice of better method. The tilting of the specimen, during the parallax method, discloses alterations in the histograms of the images acquired in the clockwise direction that limit the use of the method for materials with high roughness. The acquiring of images in only one direction and the construction of a region of interest, located in the center of the image are suggestions to turn the method most including. The linearity of the projections of features in the inclined image also suggests the possibility to carry through the reconstruction using, instead of only two, multiple images gotten in the counter-clockwise direction. The alterations proposals to modify the routine, are suggested so that the program can be applied in a more comprehensive form, independent of the quality of the observed fracture surface. (author)

  20. Development of a Fully Automated Guided Wave System for In-Process Cure Monitoring of CFRP Composite Laminates

    Science.gov (United States)

    Hudson, Tyler B.; Hou, Tan-Hung; Grimsley, Brian W.; Yaun, Fuh-Gwo

    2016-01-01

    A guided wave-based in-process cure monitoring technique for carbon fiber reinforced polymer (CFRP) composites was investigated at NASA Langley Research Center. A key cure transition point (vitrification) was identified and the degree of cure was monitored using metrics such as amplitude and time of arrival (TOA) of guided waves. Using an automated system preliminarily developed in this work, high-temperature piezoelectric transducers were utilized to interrogate a twenty-four ply unidirectional composite panel fabricated from Hexcel (Registered Trademark) IM7/8552 prepreg during cure. It was shown that the amplitude of the guided wave increased sharply around vitrification and the TOA curve possessed an inverse relationship with degree of cure. The work is a first step in demonstrating the feasibility of transitioning the technique to perform in-process cure monitoring in an autoclave, defect detection during cure, and ultimately a closed-loop process control to maximize composite part quality and consistency.

  1. Inclusion of CFRP-Epoxy Composite for End Anchorage in NSM-Epoxy Strengthened Beams

    Directory of Open Access Journals (Sweden)

    Md. Akter Hosen

    2015-01-01

    Full Text Available Nowadays, the use of near surface mounted (NSM technique strengthening reinforced concrete (RC structural members is going very popular. The failure modes of NSM strengthened reinforced concrete (RC beams have been shown to be largely due to premature failure such as concrete cover separation. In this study, CFRP U-wrap end anchorage with CFRP fabrics was used to eliminate the concrete cover separation failure. A total of eight RC rectangular beam specimens of 125 mm width, 250 mm depth, and 2300 mm length were tested. One specimen was kept unstrengthened as a reference; three specimens were strengthened with NSM steel bars and the remaining four specimens were strengthened with NSM steel bars together with the U-wrap end anchorage. The experimental results showed that wrapped strengthened beams had higher flexural strength and superior ductility performance. The results also show that these beams had less deflection, strain, crack width, and spacing.

  2. Analyzing the Effect of Machining Parameters Setting to the Surface Roughness during End Milling of CFRP-Aluminium Composite Laminates

    Directory of Open Access Journals (Sweden)

    M. Nurhaniza

    2016-01-01

    Full Text Available The quality of the machining is measured from surface finished and it is considered as the most important aspect in composite machining. An appropriate and optimum machining parameters setting is crucial during machining operation in order to enhance the surface quality. The objective of this research is to analyze the effect of machining parameters on the surface quality of CFRP-Aluminium in CNC end milling operation with PCD tool. The milling parameters evaluated are spindle speed, feed rate, and depth of cut. The L9 Taguchi orthogonal arrays, signal-to-noise (S/N ratio, and analysis of variance (ANOVA are employed to analyze the effect of these cutting parameters. The analysis of the results indicates that the optimal cutting parameters combination for good surface finish is high cutting speed, low feed rate, and low depth of cut.

  3. Open Circuit Resonant (SansEC) Sensor for Composite Damage Detection and Diagnosis in Aircraft Lightning Environments

    Science.gov (United States)

    Wang, Chuantong; Dudley, Kenneth L.; Szatkowski, George N.

    2012-01-01

    Composite materials are increasingly used in modern aircraft for reducing weight, improving fuel efficiency, and enhancing the overall design, performance, and manufacturability of airborne vehicles. Materials such as fiberglass reinforced composites (FRC) and carbon-fiber-reinforced polymers (CFRP) are being used to great advantage in airframes, wings, engine nacelles, turbine blades, fairings, fuselage and empennage structures, control surfaces and coverings. However, the potential damage from the direct and indirect effects of lightning strikes is of increased concern to aircraft designers and operators. When a lightning strike occurs, the points of attachment and detachment on the aircraft surface must be found by visual inspection, and then assessed for damage by maintenance personnel to ensure continued safe flight operations. In this paper, a new method and system for aircraft in-situ damage detection and diagnosis are presented. The method and system are based on open circuit (SansEC) sensor technology developed at NASA Langley Research Center. SansEC (Sans Electric Connection) sensor technology is a new technical framework for designing, powering, and interrogating sensors to detect damage in composite materials. Damage in composite material is generally associated with a localized change in material permittivity and/or conductivity. These changes are sensed using SansEC. Unique electrical signatures are used for damage detection and diagnosis. NASA LaRC has both experimentally and theoretically demonstrated that SansEC sensors can be effectively used for in-situ composite damage detection.

  4. Advantages of using CFRP cables in orthogonally loaded cable structures

    Directory of Open Access Journals (Sweden)

    Bernd Zwingmann

    2016-07-01

    Full Text Available Carbon Fiber Reinforced Polymer (CFRP is an advanced composite material with advantages of high strength and light weight, giving it great potential to be a new, reliable cable material. Ideal structures for CFRP cables are orthogonally loaded cable structures, where cables are loaded orthogonally or approximately orthogonally by external loads. Using CFRP cables in such structures, e.g. cable roofs and cable facades, has advantages over traditional steel cable structures. In order to demonstrate this point, two typical orthogonally loaded cable structures, i.e. a CFRP spoked wheel cable roof and a CFRP cable net façade, were investigated in a case study. Their mechanical properties and economies are compared with that of the steel counterparts. Results show that CFRP cables can effectively improve the mechanical and economical performances of orthogonally loaded cable structures; furthermore, the advantages of applying CFRP cables for cable net facade are more obvious than that for spoked wheel cable roof.

  5. Visual inspection reliability for composite aircraft structures

    OpenAIRE

    Cook, Lawrence

    2009-01-01

    This thesis presents a study of the effects of surface colour, surface finish and dent shape on the visual inspection reliability of 3D surface indentations common in shape to those produced by impact damage to carbon fibre reinforced epoxy laminates. Falling weight (2.5kg) apparatus was used to produce impact damage to non-painted, non-mesh Hexcel AS4/ 8552 carbon fibre reinforced plastic (CFRP) laminates and painted AS4/ 8552 laminates containing bronze mesh and glass fabric ...

  6. Composite Axial Flow Propulsor for Small Aircraft

    Directory of Open Access Journals (Sweden)

    R. Poul

    2005-01-01

    Full Text Available This work focuses on the design of an axial flow ducted fan driven by a reciprocating engine. The solution minimizes the turbulization of the flow around the aircraft. The fan has a rotor - stator configuration. Due to the need for low weight of the fan, a carbon/epoxy composite material was chosen for the blades and the driving shaft.The fan is designed for optimal isentropic efficiency and free vortex flow. A stress analysis of the rotor blade was performed using the Finite Element  Method. The skin of the blade is calculated as a laminate and the foam core as a solid. A static and dynamic analysis were made. The RTM technology is compared with other technologies and is described in detail. 

  7. Strain Rate Effects in CFRP Used For Blast Mitigation

    Directory of Open Access Journals (Sweden)

    Sarah. L. Orton

    2014-04-01

    Full Text Available The purpose of this research is to gain a better understanding of strain rate effects in carbon fiber reinforced polymer (CFRP laminates exposed to blast loading. The use of CFRP offers an attractive option for mitigating structures exposed to blasts. However, the effect of high strain rates in CFRP composites commonly used in the civil industry is unknown. This research conducted tensile tests of 21 CFRP coupons using a hydraulically powered dynamic loader. The strain rates ranged from 0.0015 s−1 to 7.86 s−1 and are representative of strain rates that CFRP may see in a blast when used to strengthen reinforced concrete structures. The results of the testing showed no increase in the tensile strength or stiffness of the CFRP at the higher strain rates. In addition, the results showed significant scatter in the tensile strengths possibly due to the rate of loading or manufacture of the coupon.

  8. Design of Carbon Composite Driveshaft for Ultralight Aircraft Propulsion System

    Directory of Open Access Journals (Sweden)

    R. Poul

    2006-01-01

    Full Text Available This paper deals with the design of the carbon fibre composite driveshaft. This driveshaft will be used for connection between piston engine and propulsor of the type of axial-flow fan. Three different versions of driveshaft were designed and produced. Version 1 if completely made of Al alloy. Version 2 is of hybrid design where the central part is made of high strength carbon composite and flanges are made of Al alloy. Adhesive bond is used for connection between flanges and the central CFRP tube. Version 3 differs from the version 2 by aplication of ultrahigh-strength carbon fibre on the central part. Dimensions and design conditions are equal for all three versions to obtain simply comparable results. Calculations of driveshafts are described in the paper. 

  9. Analytical and Experimental Study of Residual Stresses in CFRP

    Directory of Open Access Journals (Sweden)

    Chia-Chin Chiang

    2013-01-01

    Full Text Available Fiber Bragg Grating sensors (FBGs have been utilized in various engineering and photoelectric fields because of their good environment tolerance. In this research, residual stresses of carbon fiber reinforced polymer composites (CFRP were studied using both experimental and analytical approach. The FBGs were embedded inside middle layers of CFRP to study the formation of residual stress during curing process. Finite element analysis was performed using ABAQUS software to simulate the CFRP curing process. Both experimental and simulation results showed that the residual stress appeared during cooling process and the residual stresses could be released when the CFRP was machined to a different shape.

  10. Design and Analysis of Composite Propeller Blade for Aircraft

    Directory of Open Access Journals (Sweden)

    Madhusudhan BM

    2014-09-01

    Full Text Available Fiber reinforced composites is used for twin blade propeller because of its high strength, low temperature applications. Fiber has to be oriented in the loading direction while designing the composite propeller blade. The blade geometry and design are more complex involving many controlling parameters. In the present work a methodology to design a composite propeller to analyze its strength and deformation using ANSYS software. The weight of the composite blade is reduced compared to wooden blade by adopting the shell model. The present work is to carryout the static analysis of composite propeller which is a combination CFRP (Carbon Fiber Reinforced Plastics and epoxy resin materials. In order to evaluate the effectiveness of the composite blade over wooden stress analysis is performed on both the blades. To define the orientation and number of layers in the composite blade ANSYS classic software is used. From the results, the stresses of composite propeller obtained in static analysis are within the allowable stress limit. The deflection of the composite blade is less compared to the wooden blade.

  11. NASA service experience with composite components. [for aircraft structures

    Science.gov (United States)

    Dexter, H. B.; Chapman, A. J.

    1980-01-01

    NASA Langley has been active in sponsoring flight service programs with advanced composites during the past decade. A broad data base and confidence in the durability of composite structures are being developed. Flight service experience is reported for more than 140 composite aircraft components with up to 8 years service and almost two million successful component flight hours. Composite components are being evaluated on Boeing, Douglas, and Lockheed transport aircraft. Components are currently under development for service evaluation on Bell and Sikorsky helicopters. Design concepts and inspection and maintenance results are reported for components currently in service. Components under development in the NASA Aircraft Energy Efficiency (ACEE) program are discussed. Results of flight, outdoor ground, and controlled laboratory environmental tests on composite materials used in the flight service programs are also presented.

  12. Composite Bonded Joints’ Lifetime for Aircraft under Random Fatigue Loads

    Directory of Open Access Journals (Sweden)

    Wei Guo Shen

    2014-04-01

    Full Text Available In this present study, a lifetime prediction model of composite bonded joint in aircraft is developed based on variation of its elastic modulus under Random Fatigue Loads (RFL of aircraft and its approach is deduced by Miner linear damage accumulated theory. Considering some assumptions, this prediction model is conservative for aircraft engineering industry. Finally, simulation approach and analysis is developed and done for verification of deduction models. As a precondition, some assumptions are defined for simulation and verification. From simulating results, we can give a conclusion that models are properly accuracy for further study and engineering application.

  13. Low-Cost Composite Materials and Structures for Aircraft Applications

    Science.gov (United States)

    Deo, Ravi B.; Starnes, James H., Jr.; Holzwarth, Richard C.

    2003-01-01

    A survey of current applications of composite materials and structures in military, transport and General Aviation aircraft is presented to assess the maturity of composites technology, and the payoffs realized. The results of the survey show that performance requirements and the potential to reduce life cycle costs for military aircraft and direct operating costs for transport aircraft are the main reasons for the selection of composite materials for current aircraft applications. Initial acquisition costs of composite airframe components are affected by high material costs and complex certification tests which appear to discourage the widespread use of composite materials for aircraft applications. Material suppliers have performed very well to date in developing resin matrix and fiber systems for improved mechanical, durability and damage tolerance performance. The next challenge for material suppliers is to reduce material costs and to develop materials that are suitable for simplified and inexpensive manufacturing processes. The focus of airframe manufacturers should be on the development of structural designs that reduce assembly costs by the use of large-scale integration of airframe components with unitized structures and manufacturing processes that minimize excessive manual labor.

  14. Optimisation of the geometry of the drill bit and process parameters for cutting hybrid composite/metal structures in new aircrafts

    Science.gov (United States)

    Isbilir, Ozden

    Owing to their desirable strength-to-weight characteristics, carbon fibre reinforced polymer composites have been favourite materials for structural applications in different industries such as aerospace, transport, sports and energy. They provide a weight reduction in whole structure and consequently decrease fuel consumption. The use of lightweight materials such as titanium and its alloys in modern aircrafts has also increased significantly in the last couple of decades. Titanium and its alloys offer high strength/weight ratio, high compressive and tensile strength at high temperatures, low density, excellent corrosion resistance, exceptional erosion resistance, superior fatigue resistance and relatively low modulus of elasticity. Although composite/metal hybrid structures are increasingly used in airframes nowadays, number of studies regarding drilling of composite/metal stacks is very limited. During drilling of multilayer materials different problems may arise due to very different attributes of these materials. Machining conditions of drilling such structures play an important role on tool wear, quality of holes and cost of machining.. The research work in this thesis is aimed to investigate drilling of CFRP/Ti6Al4V hybrid structure and to optimize process parameters and drill geometry. The research work consist complete experimental study including drilling tests, in-situ and post measurements and related analysis; and finite element analysis including fully 3-D finite element models. The experimental investigations focused on drilling outputs such as thrust force, torque, delamination, burr formation, surface roughness and tool wear. An algorithm was developed to analyse drilling induced delamination quantitatively based on the images. In the numerical analysis, novel 3-D finite element models of drilling of CFRP, Ti6Al4V and CFRP/Ti6Al4V hybrid structure were developed with the use of 3-D complex drill geometries. A user defined subroutine was developed

  15. Open Circuit Resonant (SansEC) Sensor Technology for Lightning Mitigation and Damage Detection and Diagnosis for Composite Aircraft Applications

    Science.gov (United States)

    Szatkowski, George N.; Dudley, Kenneth L.; Smith, Laura J.; Wang, Chuantong; Ticatch, Larry A.

    2014-01-01

    aircraft composite damage detection and diagnosis. Experimental test results on seeded fault damage coupons and computational modeling simulation results are presented. This paper also presents the shielding effectiveness along with the lightning direct effect test results from several different SansEC LSP and baseline protected and unprotected carbon fiber reinforced polymer (CFRP) test panels struck at 40 and 100 kiloamperes following a universal common practice test procedure to enable damage comparisons between SansEC LSP configurations and common practice copper mesh LSP approaches. The SansEC test panels were mounted in a LSP test bed during the lightning test. Electrical, mechanical and thermal parameters were measured during lightning attachment and are presented with post test nondestructive inspection comparisons. The paper provides correlational results between the SansEC sensors computed electric field distribution and the location of the lightning attachment on the sensor trace and visual observations showing the SansEC sensor's affinity for dispersing the lightning attachment.

  16. Low velocity blunt impacts on composite aircraft structures

    OpenAIRE

    Whisler, Daniel A.

    2009-01-01

    As composites are increasingly used for primary structures in commercial aircrafts, it is necessary to understand damage initiation for composites subject to low velocity impacts from service conditions, maintenance, and other ground equipment mishaps. In particular, collisions with ground vehicles can present a wide area, blunt impact. Therefore, the effects of bluntness of an impactor are of interest as this is related to both the external visual detectability of an impact event, as well as...

  17. Problems and perspectives of application of composite materials in aircraft

    OpenAIRE

    Savchenko, V. A.

    2015-01-01

    Purpose. Aircraft uses a very wide range of constructional technologies, but the technological progress and economic crisis lead to the research of composite materials with high mechanical and operational properties level. The advantage of such materials is the low density, which reduces the overall weight and increase fuel economy and increases airplanes' passenger capacity. Methodology. The values of the exploitation characteristics (specific strength, specific stiffness) of composite mater...

  18. Bending Moment Decrease of Reinforced Concrete Beam Supported by Additional CFRP

    Directory of Open Access Journals (Sweden)

    Mykolas Daugevičius

    2011-04-01

    Full Text Available The calculation method of reinforced concrete beam with additional CFRP composite is proposed in this article. This method estimates tangential angular concrete deformations in tensioned beam layers between steel and bonded carbon fiber reinforced polymer. The horizontal slip of CFRP composite reduce beam bending moment capacity. An additional coefficient to reduce CFRP resultant force is necessary for better precision of bending moment capacity. Also, various calculation methods of bending moment capacity are considered. Article in Lithuanian

  19. Development of Textile Reinforced Composites for Aircraft Structures

    Science.gov (United States)

    Dexter, H. Benson

    1998-01-01

    NASA has been a leader in development of composite materials for aircraft applications during the past 25 years. In the early 1980's NASA and others conducted research to improve damage tolerance of composite structures through the use of toughened resins but these resins were not cost-effective. The aircraft industry wanted affordable, robust structures that could withstand the rigors of flight service with minimal damage. The cost and damage tolerance barriers of conventional laminated composites led NASA to focus on new concepts in composites which would incorporate the automated manufacturing methods of the textiles industry and which would incorporate through-the-thickness reinforcements. The NASA Advanced Composites Technology (ACT) Program provided the resources to extensively investigate the application of textile processes to next generation aircraft wing and fuselage structures. This paper discusses advanced textile material forms that have been developed, innovative machine concepts and key technology advancements required for future application of textile reinforced composites in commercial transport aircraft. Multiaxial warp knitting, triaxial braiding and through-the-thickness stitching are the three textile processes that have surfaced as the most promising for further development. Textile reinforced composite structural elements that have been developed in the NASA ACT Program are discussed. Included are braided fuselage frames and window-belt reinforcements, woven/stitched lower fuselage side panels, stitched multiaxial warp knit wing skins, and braided wing stiffeners. In addition, low-cost processing concepts such as resin transfer molding (RTM), resin film infusion (RFI), and vacuum-assisted resin transfer molding (VARTM) are discussed. Process modeling concepts to predict resin flow and cure in textile preforms are also discussed.

  20. Adhesive bonding of composite aircraft structures: Challenges and recent developments

    Science.gov (United States)

    Pantelakis, Sp.; Tserpes, K. I.

    2014-01-01

    In this review paper, the challenges and some recent developments of adhesive bonding technology in composite aircraft structures are discussed. The durability of bonded joints is defined and presented for parameters that may influence bonding quality. Presented is also, a numerical design approach for composite joining profiles used to realize adhesive bonding. It is shown that environmental ageing and pre-bond contamination of bonding surfaces may degrade significantly fracture toughness of bonded joints. Moreover, it is obvious that additional research is needed in order to design joining profiles that will enable load transfer through shearing of the bondline. These findings, together with the limited capabilities of existing non-destructive testing techniques, can partially explain the confined use of adhesive bonding in primary composite aircraft structural parts.

  1. Development of composite wing carrythrough bulkheads for fighter aircraft

    Science.gov (United States)

    Goering, J. C.; Behrens, R. S.; Libeskind, Mark

    1990-01-01

    Potential weight savings due to the use of composite materials for highly loaded primary structures are being demonstrated through the design, fabrication, and test of an all composite wing carrythrough bulkhead for the F/A-18 fighter aircraft. A one piece composite design which results in a 24 percent weight savings, relative to the existing aluminum bulkhead, was developed. Critical details of this design were evaluated through element tests, and a full scale prototype component was fabricated. The structural integrity of this design will be demonstrated in a comprehensive full scale test program.

  2. Advanced composite elevator for Boeing 727 aircraft

    Science.gov (United States)

    1979-01-01

    Detail design activities are reported for a program to develop an advanced composites elevator for the Boeing 727 commercial transport. Design activities include discussion of the full scale ground test and flight test activities, the ancillary test programs, sustaining efforts, weight status, and the production status. Prior to flight testing of the advanced composites elevator, ground, flight flutter, and stability and control test plans were reviewed and approved by the FAA. Both the ground test and the flight test were conducted according to the approved plan, and were witnessed by the FAA. Three and one half shipsets have now been fabricated without any significant difficulty being encountered. Two elevator system shipsets were weighed, and results validated the 26% predicted weight reduction. The program is on schedule.

  3. Flutter behaviour of composite aircraft wings

    OpenAIRE

    Ashawesh, Gamal Mohamed

    1999-01-01

    This research work presents series of investigations into the structural dynamics and dynamic aeroelastic (flutter) behaviour of composite and metal wings. The study begins with a literature review where the development and an over view of the previous investigations in this field are presented. Static stiffness is very important to any type of analysis, especially in both dynamic and flutter analysis as in this case. Therefore, different methods are presented and used for the ...

  4. Durability of commercial aircraft and helicopter composite structures

    Science.gov (United States)

    Dexter, H. B.

    1982-01-01

    The development of advanced composite technology during the past decade is discussed. Both secondary and primary components fabricated with boron, graphite, and Kevlar composites are evaluated. Included are spoilers, rudders, and fairings on commercial transports, boron/epoxy reinforced wing structure on C-130 military transports, and doors, fairings, tail rotors, vertical fins, and horizontal stabilizers on commercial helicopters. The development of composite structures resulted in advances in design and manufacturing technology for secondary and primary composite structures for commercial transports. Design concepts and inspection and maintenance results for the components in service are reported. The flight, outdoor ground, and controlled laboratory environmental effects on composites were also determined. Effects of moisture absorption, ultraviolet radiation, aircraft fuels and fluids, and sustained tensile stress are included. Critical parameters affecting the long term durability of composite materials are identified.

  5. Damage Detection in CFRP Plates Using Spectral Entropy

    Directory of Open Access Journals (Sweden)

    E. Castro

    2014-01-01

    Full Text Available Damage detection techniques using vibrations are based on measuring the changes in the vibration parameters of a structure. This paper studies the viability of the spectral entropy as a new damage detection parameter to detect the presence of damage in a composite fiber reinforced polymers (CFRP plate. To carry out this study, the vibrations in a CFRP plate with and without damage were measured and the correlation between damage and spectral entropy has been researched.

  6. Dynamic tests of composite panels of an aircraft wing

    Science.gov (United States)

    Splichal, Jan; Pistek, Antonin; Hlinka, Jiri

    2015-10-01

    The paper describes the analysis of aerospace composite structures under dynamic loading. Today, it is common to use design procedures based on assumption of static loading only, and dynamic loading is rarely assumed and applied in design and certification of aerospace structures. The paper describes the application of dynamic loading for the design of aircraft structures, and the validation of the procedure on a selected structure. The goal is to verify the possibility of reducing the weight through improved design/modelling processes using dynamic loading instead of static loading. The research activity focuses on the modelling and testing of a composite panel representing a local segment of an aircraft wing section, investigating in particular the buckling behavior under dynamic loading. Finite Elements simulation tools are discussed, as well as the advantages of using a digital optical measurement system for the evaluation of the tests. The comparison of the finite element simulations with the results of the tests is presented.

  7. Modelling the impact of aircraft emissions on atmospheric composition

    Science.gov (United States)

    Wasiuk, D. K.; Lowenberg, M. H.; Shallcross, D. E.

    2012-12-01

    Emissions of the trace gases CO2, CO, H2O, HC, NOx, and SOx that have the potential to perturb large scale atmospheric composition are accumulating in the atmosphere at an unprecedented rate as the demand for air traffic continues to grow. We investigate the global and regional effects of aircraft emissions on the atmosphere and climate using mathematical modelling, sensitivity simulations, and perturbation simulations and present historical and spatial distribution evolution of the global and regional number of departures, fuel burn and emissions. A comprehensive aircraft movement database spanning years 2005 - 2012, covering 225 countries and over 223 million departures on approximately 41000 unique routes serves as a basis for our investigation. We combine air traffic data with output from an aircraft performance model (fuel burn and emissions) including 80 distinct aircraft types, representing 216 of all the aircraft flown in the world in 2005 - 2012. This accounts for fuel burn and emissions for 99.5% of the total number of departures during that time. Simulations are being performed using a state of the art 3D Lagrangian global chemical transport model (CTM) CRI-STOCHEM for simulation of tropospheric chemistry. The model is applied with the CRI (Common Representative Intermediates) chemistry scheme with 220 chemical species, and 609 reactions. This allows us to study in detail the chemical cycles driven by NOx, governing the rate of formation of O3 which controls the production of OH and indirectly determines the lifetime of other greenhouse gases. We also investigate the impact of the Eyjafjallajökull eruption on the European air traffic and present a model response to the perturbation of NOx emissions that followed.

  8. Composite Structure Modeling and Analysis of Advanced Aircraft Fuselage Concepts

    Science.gov (United States)

    Mukhopadhyay, Vivek; Sorokach, Michael R.

    2015-01-01

    NASA Environmentally Responsible Aviation (ERA) project and the Boeing Company are collabrating to advance the unitized damage arresting composite airframe technology with application to the Hybrid-Wing-Body (HWB) aircraft. The testing of a HWB fuselage section with Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) construction is presently being conducted at NASA Langley. Based on lessons learned from previous HWB structural design studies, improved finite-element models (FEM) of the HWB multi-bay and bulkhead assembly are developed to evaluate the performance of the PRSEUS construction. In order to assess the comparative weight reduction benefits of the PRSEUS technology, conventional cylindrical skin-stringer-frame models of a cylindrical and a double-bubble section fuselage concepts are developed. Stress analysis with design cabin-pressure load and scenario based case studies are conducted for design improvement in each case. Alternate analysis with stitched composite hat-stringers and C-frames are also presented, in addition to the foam-core sandwich frame and pultruded rod-stringer construction. The FEM structural stress, strain and weights are computed and compared for relative weight/strength benefit assessment. The structural analysis and specific weight comparison of these stitched composite advanced aircraft fuselage concepts demonstrated that the pressurized HWB fuselage section assembly can be structurally as efficient as the conventional cylindrical fuselage section with composite stringer-frame and PRSEUS construction, and significantly better than the conventional aluminum construction and the double-bubble section concept.

  9. Connecting Microscale And Macroscale Damage Models In A Bayesian Framework for Fatigue Damage Prognostics Of CFRP Composites

    Data.gov (United States)

    National Aeronautics and Space Administration — Composites offer unique advantages for aerospace structures and are increasingly being adopted into newer designs. However, it is also acknowledged that given...

  10. 碳纤维预应力棱柱体复合筋混凝土梁裂缝试验研究%EXPERIMENTAL STUDY OF CRACK OF CFRP-PCPS COMPOSITES REINFORCED CONCRETE BEAMS

    Institute of Scientific and Technical Information of China (English)

    张鹏; 刘闻冰; 邓宇; 屈建; 郭加加; 余兆航; 赵思敏

    2015-01-01

    通过6根混凝土梁的抗弯静力加载试验,对碳纤维预应力棱柱体复合筋( CFRP-PCPs )混凝土梁在使用荷载作用下裂缝的分布及发展进行研究。考虑到CFRP-PCPs复合筋的影响,在我国现有《混凝土结构设计规范》相关计算方法的基础上,对CFRP-PCPs复合筋混凝土梁的裂缝间距和最大裂缝宽度计算式进行修正,并将所提出的算式的计算结果与试验结果进行了对比,分析结果表明计算值与试验值吻合程度较好。%Based on the flexural static loading test of six concrete beams, the crack distribution and development of CFRP-PCPs ( carbon fiber reinforced plastics prestressed concrete prisms ) composites reinforced concrete beams under service load were researched.Considering the influence of CFRP -PCPs composites reinforcement, the calculation methods of maximum crack width and mean crack spacing of concrete beams with CFRP -PCPs composites reinforcement in current Chinese design code for concrete structures were modified.Whose results were compared with experimental results, showing a better agreement between test values and the calculated values given by the modified formulas.

  11. Performance analysis of bonded composite doublers on aircraft structures

    Energy Technology Data Exchange (ETDEWEB)

    Roach, D.

    1995-08-01

    Researchers contend that composite repairs (or structural reinforcement doublers) offer numerous advantages over metallic patches including corrosion resistance, light weight, high strength, elimination of rivets, and time savings in installation. Their use in commercial aviation has been stifled by uncertainties surrounding their application, subsequent inspection and long-term endurance. The process of repairing or reinforcing airplane structures is time consuming and the design is dependent upon an accompanying stress and fatigue analysis. A repair that is too stiff may result in a loss of fatigue life, continued growth of the crack being repaired, and the initiation of a new flaw in the undesirable high stress field around the patch. Uncertainties in load spectrums used to design repairs exacerbates these problems as does the use of rivets to apply conventional doublers. Many of these repair or structural reinforcement difficulties can be addressed through the use of composite doublers. Primary among unknown entities are the effects of non-optimum installations and the certification of adequate inspection procedures. This paper presents on overview of a program intended to introduce composite doubler technology to the US commercial aircraft fleet. In this project, a specific composite application has been chosen on an L-1011 aircraft in order to focus the tasks on application and operation issues. Through the use of laboratory test structures and flight demonstrations on an in-service L-1011 airplane, this study is investigating composite doubler design, fabrication, installation, structural integrity, and non-destructive evaluation. In addition to providing an overview of the L-1011 project, this paper focuses on a series of fatigue and strength tests which have been conducted in order to study the damage tolerance of composite doublers. Test results to-date are presented.

  12. Smart aircraft composite structures with embedded small-diameter optical fiber sensors

    Science.gov (United States)

    Takeda, Nobuo; Minakuchi, Shu

    2012-02-01

    This talk describes the embedded optical fiber sensor systems for smart aircraft composite structures. First, a summary of the current Japanese national project on structural integrity diagnosis of aircraft composite structures is described with special emphasis on the use of embedded small-diameter optical fiber sensors including FBG sensors. Then, some examples of life-cycle monitoring of aircraft composite structures are presented using embedded small-diameter optical fiber sensors for low-cost and reliable manufacturing merits.

  13. Development of Stitched Composite Structure for Advanced Aircraft

    Science.gov (United States)

    Jegley, Dawn; Przekop, Adam; Rouse, Marshall; Lovejoy, Andrew; Velicki, Alex; Linton, Kim; Wu, Hsi-Yung; Baraja, Jaime; Thrash, Patrick; Hoffman, Krishna

    2015-01-01

    NASA has created the Environmentally Responsible Aviation Project to develop technologies which will reduce the impact of aviation on the environment. A critical aspect of this pursuit is the development of a lighter, more robust airframe that will enable the introduction of unconventional aircraft configurations. NASA and The Boeing Company are working together to develop a structural concept that is lightweight and an advancement beyond state-of-the-art composites. The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) is an integrally stiffened panel design where elements are stitched together and designed to maintain residual load-carrying capabilities under a variety of damage scenarios. With the PRSEUS concept, through-the-thickness stitches are applied through dry fabric prior to resin infusion, and replace fasteners throughout each integral panel. Through-the-thickness reinforcement at discontinuities, such as along flange edges, has been shown to suppress delamination and turn cracks, which expands the design space and leads to lighter designs. The pultruded rod provides stiffening away from the more vulnerable skin surface and improves bending stiffness. A series of building blocks were evaluated to explore the fundamental assumptions related to the capability and advantages of PRSEUS panels. These building blocks addressed tension, compression, and pressure loading conditions. The emphasis of the development work has been to assess the loading capability, damage arrestment features, repairability, post-buckling behavior, and response of PRSEUS flat panels to out-of plane pressure loading. The results of this building-block program from coupons through an 80%-scale pressure box have demonstrated the viability of a PRSEUS center body for the Hybrid Wing Body (HWB) transport aircraft. This development program shows that the PRSEUS benefits are also applicable to traditional tube-andwing aircraft, those of advanced configurations, and other

  14. PRACTICAL STUDY ON THE CFRP REINFORCEMENT

    Directory of Open Access Journals (Sweden)

    Catalina IANASI

    2016-05-01

    Full Text Available One of the defining goals of this paper is getting new resistant material which combine the qualities of basic materials that get into its composition but not to borrow from them their negative properties. In recent years, carbon fiber composites have been increasingly used in different ways in reinforcing structural elements. Specifically, the use of CFRP composite materials as reinforcement for wood beams under bending loads requires paying attention to several aspects of the problem which are presented in this paper.

  15. Ply Orientation of Carbon Fiber Reinforced Aircraft Wing - A Parametric Study

    Directory of Open Access Journals (Sweden)

    Dr. Alice Mathai

    2014-05-01

    Full Text Available In the present day scenario, use of carbon fiber composites has been extended to a large number of aircraft components which includes structural and non-structural components. Carbon fiber reinforced polymer (CFRP is a composite material which consists of laminates having reinforcing fibers (carbon of significant strength embedded in a matrix material. Each lamina can have distinct fiber orientations which may vary from the adjoining lamina. The present study focuses on the effect of the ply orientation on the strength of the panels. The wing of a subsonic aircraft was modeled in the ANSYS software. The performance of wing under the application of loads was studied by varying the orientation of fiber layers. From the study, it was observed that the variation in stress occurs with variation in orientation of fiber layers of CFRP composites.

  16. Damage in woven CFRP laminates under impact loading

    Directory of Open Access Journals (Sweden)

    Silberschmidt V.V.

    2012-08-01

    Full Text Available Carbon fibre-reinforced polymer (CFRP composites used in sports products can be exposed to different in-service conditions such as large dynamic bending deformations caused by impact loading. Composite materials subjected to such loads demonstrate various damage modes such as matrix cracking, delamination and, ultimately, fabric fracture. Damage evolution affects both in-service properties and performance of CFRP that can deteriorate with time. These failure modes need adequate means of analysis and investigation, the major approaches being experimental characterisation and numerical simulations. This research deals with a deformation behaviour and damage in composite laminates due to dynamic bending. Experimental tests are carried out to characterise the behaviour of a woven CFRP material under large-deflection dynamic bending in impact tests carried out to obtain the force-time and absorbed energy profiles for CFRP laminates. Damage in the impacted laminates is analysed using optical microscopy. Numerical simulations are performed to study the deformation behaviour and damage in CFRP for cases of large-deflection bending based on three-dimensional finite-element models implemented in the commercial code Abaqus/Explicit. Multiple layers of bilinear cohesive-zone elements are employed to model the initiation and progression of inter-ply delamination observed in the microscopy studies. The obtained results of simulations show good agreement with experimental data.

  17. Damage in woven CFRP laminates under impact loading

    Science.gov (United States)

    Ullah, H.; Harland, A. R.; Silberschmidt, V. V.

    2012-08-01

    Carbon fibre-reinforced polymer (CFRP) composites used in sports products can be exposed to different in-service conditions such as large dynamic bending deformations caused by impact loading. Composite materials subjected to such loads demonstrate various damage modes such as matrix cracking, delamination and, ultimately, fabric fracture. Damage evolution affects both in-service properties and performance of CFRP that can deteriorate with time. These failure modes need adequate means of analysis and investigation, the major approaches being experimental characterisation and numerical simulations. This research deals with a deformation behaviour and damage in composite laminates due to dynamic bending. Experimental tests are carried out to characterise the behaviour of a woven CFRP material under large-deflection dynamic bending in impact tests carried out to obtain the force-time and absorbed energy profiles for CFRP laminates. Damage in the impacted laminates is analysed using optical microscopy. Numerical simulations are performed to study the deformation behaviour and damage in CFRP for cases of large-deflection bending based on three-dimensional finite-element models implemented in the commercial code Abaqus/Explicit. Multiple layers of bilinear cohesive-zone elements are employed to model the initiation and progression of inter-ply delamination observed in the microscopy studies. The obtained results of simulations show good agreement with experimental data.

  18. Interlaminar Fracture Toughness of CFRP Laminates Incorporating Multi-Walled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Elisa Borowski

    2015-06-01

    Full Text Available Carbon fiber reinforced polymer (CFRP laminates exhibit limited fracture toughness due to characteristic interlaminar fiber-matrix cracking and delamination. In this article, we demonstrate that the fracture toughness of CFRP laminates can be improved by the addition of multi-walled carbon nanotubes (MWCNTs. Experimental investigations and numerical modeling were performed to determine the effects of using MWCNTs in CFRP laminates. The CFRP specimens were produced using an epoxy nanocomposite matrix reinforced with carboxyl functionalized multi-walled carbon nanotubes (COOH–MWCNTs. Four MWCNTs contents of 0.0%, 0.5%, 1.0%, and 1.5% per weight of the epoxy resin/hardener mixture were examined. Double cantilever beam (DCB tests were performed to determine the mode I interlaminar fracture toughness of the unidirectional CFRP composites. This composite material property was quantified using the critical energy release rate, GIC. The experimental results show a 25%, 20%, and 17% increase in the maximum interlaminar fracture toughness of the CFRP composites with the addition of 0.5, 1.0, and 1.5 wt% MWCNTs, respectively. Microstructural investigations using Fourier transform infrared (FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS verify that chemical reactions took place between the COOH–MWCNTs and the epoxy resin, supporting the improvements experimentally observed in the interlaminar fracture toughness of the CFRP specimens containing MWCNTs. Finite element (FE simulations show good agreement with the experimental results and confirm the significant effect of MWCNTs on the interlaminar fracture toughness of CFRP.

  19. A study on the utilization of advanced composites in commercial aircraft wing structure: Executive summary

    Science.gov (United States)

    Watts, D. J.

    1978-01-01

    The overall wing study objectives are to study and plan the effort by commercial transport aircraft manufacturers to accomplish the transition from current conventional materials and practices to extensive use of advanced composites in wings of aircraft that will enter service in the 1985-1990 time period. Specific wing study objectives are to define the technology and data needed to support an aircraft manufacturer's commitment to utilize composites primary wing structure in future production aircraft and to develop plans for a composite wing technology program which will provide the needed technology and data.

  20. Finite element analysis of drilling in carbon fiber reinforced polymer composites

    International Nuclear Information System (INIS)

    Carbon fiber reinforced polymer composite (CFRP) laminates are attractive for many applications in the aerospace industry especially as aircraft structural components due to their superior properties. Usually drilling is an important final machining process for components made of composite laminates. In drilling of CFRP, it is an imperative task to determine the maximum critical thrust forces that trigger inter-laminar and intra-laminar damage modes owing to highly anisotropic fibrous media; and negotiate integrity of composite structures. In this paper, a 3D finite element (FE) model of drilling in CFRP composite laminate is developed, which accurately takes into account the dynamic characteristics involved in the process along with the accurate geometrical considerations. A user defined material model is developed to account for accurate though thickness response of composite laminates. The average critical thrust forces and torques obtained using FE analysis, for a set of machining parameters are found to be in good agreement with the experimental results from literature.

  1. Finite element analysis of drilling in carbon fiber reinforced polymer composites

    Science.gov (United States)

    Phadnis, V. A.; Roy, A.; Silberschmidt, V. V.

    2012-08-01

    Carbon fiber reinforced polymer composite (CFRP) laminates are attractive for many applications in the aerospace industry especially as aircraft structural components due to their superior properties. Usually drilling is an important final machining process for components made of composite laminates. In drilling of CFRP, it is an imperative task to determine the maximum critical thrust forces that trigger inter-laminar and intra-laminar damage modes owing to highly anisotropic fibrous media; and negotiate integrity of composite structures. In this paper, a 3D finite element (FE) model of drilling in CFRP composite laminate is developed, which accurately takes into account the dynamic characteristics involved in the process along with the accurate geometrical considerations. A user defined material model is developed to account for accurate though thickness response of composite laminates. The average critical thrust forces and torques obtained using FE analysis, for a set of machining parameters are found to be in good agreement with the experimental results from literature.

  2. Study on properties of CFRP fabricated by VA-RTM process

    Science.gov (United States)

    Jeoung, Sun Kyoung; Hwang, Ye Jin; Lee, Hyun Wook; Son, Soon Keun; Kim, Hyung Sik; Ha, Jin Uk

    2016-03-01

    Carbon fiber reinforced plastics (CFRP) have a lot of attention from industry and academia due to its excellent mechanical property. It has been used for aircraft, automotive and so on, since it can replace metallic materials and reduce total weight with increased physical properties. However, the manufacturing process and the material cost are still challenging to be commercialized in the automotive market. Therefore, many researchers are trying to minimize materials and process cost for broadening their applications. In this study, thermoset epoxy resins were used for binder of CFRP. Epoxy resins were investigated in order to figure out optimized curing speed under vacuum assisted resin transfer molding (VARTM) processing condition. Mechanical properties of CFRP with different carbon fiber orientation and woven carbon fiber were compared to mathematically simulated results. In order to develop the application of automobile component, reliability tests of CFRP were carried out. Tensile strength of CFRP is increased when the orientation angle between fiber and axis of load was decreased (90°→ 0°). It is considered that epoxy and carbon fiber absorbed the tensile energy because the orientation of fiber and the load bearing are matched with axis direction. In addition, the CFRP automobile engine hood was fabricated by VARTM process. Drop weight impact tests (20kg & 100kg weight) were carried out in order to simulate crash performance of CFRP engine hoods.

  3. Application of CFRP with High Hydrogen Gas Barrier Characteristics to Fuel Tanks of Space Transportation System

    Science.gov (United States)

    Yonemoto, Koichi; Yamamoto, Yuta; Okuyama, Keiichi; Ebina, Takeo

    In the future, carbon fiber reinforced plastics (CFRPs) with high hydrogen gas barrier performance will find wide applications in all industrial hydrogen tanks that aim at weight reduction; the use of such materials will be preferred to the use of conventional metallic materials such as stainless steel or aluminum. The hydrogen gas barrier performance of CFRP will become an important issue with the introduction of hydrogen-fuel aircraft. It will also play an important role in realizing fully reusable space transportation system that will have high specific tensile CFRP structures. Such materials are also required for the manufacture of high-pressure hydrogen gas vessels for use in the fuel cell systems of automobiles. This paper introduces a new composite concept that can be used to realize CFRPs with high hydrogen gas barrier performance for applications in the cryogenic tanks of fully reusable space transportation system by the incorporation of a nonmetallic crystal layer, which is actually a dense and highly oriented clay crystal laminate. The preliminary test results show that the hydrogen gas barrier characteristics of this material after cryogenic heat shocks and cyclic loads are still better than those of other polymer materials by approximately two orders of magnitude.

  4. Rotary ultrasonic machining of CFRP: a mechanistic predictive model for cutting force.

    Science.gov (United States)

    Cong, W L; Pei, Z J; Sun, X; Zhang, C L

    2014-02-01

    Cutting force is one of the most important output variables in rotary ultrasonic machining (RUM) of carbon fiber reinforced plastic (CFRP) composites. Many experimental investigations on cutting force in RUM of CFRP have been reported. However, in the literature, there are no cutting force models for RUM of CFRP. This paper develops a mechanistic predictive model for cutting force in RUM of CFRP. The material removal mechanism of CFRP in RUM has been analyzed first. The model is based on the assumption that brittle fracture is the dominant mode of material removal. CFRP micromechanical analysis has been conducted to represent CFRP as an equivalent homogeneous material to obtain the mechanical properties of CFRP from its components. Based on this model, relationships between input variables (including ultrasonic vibration amplitude, tool rotation speed, feedrate, abrasive size, and abrasive concentration) and cutting force can be predicted. The relationships between input variables and important intermediate variables (indentation depth, effective contact time, and maximum impact force of single abrasive grain) have been investigated to explain predicted trends of cutting force. Experiments are conducted to verify the model, and experimental results agree well with predicted trends from this model.

  5. CFRP panel concept design study for the CCAT

    Science.gov (United States)

    Martin, Robert N.; Romeo, Robert C.; Kingsley, Jeffrey S.

    2006-06-01

    Under contract from the Cornell-Caltech Atacama Telescope Project (CCAT), Composite Mirror Applications, Inc. (CMA) has undertaken a feasibility design study for the use of Carbon Fiber Reinforced Plastic (CFRP) panels in forming the primary mirror surface. We review some of the past projects using CFRP panel technology for millimeter and submillimeter wavelength radio astronomy telescopes. Pros and cons of the technology are discussed. A particular panel configuration was proposed and computer modeled with finite element analysis (FEA). The technology of replicated CFRP panels for short wavelength radio astronomical telescopes is mature and cost effective. For shorter wavelengths into the IR and visible, it is becoming a very attractive alternative to traditional, heavy glass or metal technologies.

  6. Material Distribution Optimization for the Shell Aircraft Composite Structure

    Science.gov (United States)

    Shevtsov, S.; Zhilyaev, I.; Oganesyan, P.; Axenov, V.

    2016-09-01

    One of the main goal in aircraft structures designing isweight decreasing and stiffness increasing. Composite structures recently became popular in aircraft because of their mechanical properties and wide range of optimization possibilities.Weight distribution and lay-up are keys to creating lightweight stiff strictures. In this paperwe discuss optimization of specific structure that undergoes the non-uniform air pressure at the different flight conditions and reduce a level of noise caused by the airflowinduced vibrations at the constrained weight of the part. Initial model was created with CAD tool Siemens NX, finite element analysis and post processing were performed with COMSOL Multiphysicsr and MATLABr. Numerical solutions of the Reynolds averaged Navier-Stokes (RANS) equations supplemented by k-w turbulence model provide the spatial distributions of air pressure applied to the shell surface. At the formulation of optimization problem the global strain energy calculated within the optimized shell was assumed as the objective. Wall thickness has been changed using parametric approach by an initiation of auxiliary sphere with varied radius and coordinates of the center, which were the design variables. To avoid a local stress concentration, wall thickness increment was defined as smooth function on the shell surface dependent of auxiliary sphere position and size. Our study consists of multiple steps: CAD/CAE transformation of the model, determining wind pressure for different flow angles, optimizing wall thickness distribution for specific flow angles, designing a lay-up for optimal material distribution. The studied structure was improved in terms of maximum and average strain energy at the constrained expense ofweight growth. Developed methods and tools can be applied to wide range of shell-like structures made of multilayered quasi-isotropic laminates.

  7. Aircraft

    Science.gov (United States)

    Hibbs, Bart D.; Lissaman, Peter B. S.; Morgan, Walter R.; Radkey, Robert L.

    1998-01-01

    This disclosure provides a solar rechargeable aircraft that is inexpensive to produce, is steerable, and can remain airborne almost indefinitely. The preferred aircraft is a span-loaded flying wing, having no fuselage or rudder. Travelling at relatively slow speeds, and having a two-hundred foot wingspan that mounts photovoltaic cells on most all of the wing's top surface, the aircraft uses only differential thrust of its eight propellers to turn. Each of five sections of the wing has one or more engines and photovoltaic arrays, and produces its own lift independent of the other sections, to avoid loading them. Five two-sided photovoltaic arrays, in all, are mounted on the wing, and receive photovoltaic energy both incident on top of the wing, and which is incident also from below, through a bottom, transparent surface. The aircraft is capable of a top speed of about ninety miles per hour, which enables the aircraft to attain and can continuously maintain altitudes of up to sixty-five thousand feet. Regenerative fuel cells in the wing store excess electricity for use at night, such that the aircraft can sustain its elevation indefinitely. A main spar of the wing doubles as a pressure vessel that houses hydrogen and oxygen gasses for use in the regenerative fuel cell. The aircraft has a wide variety of applications, which include weather monitoring and atmospheric testing, communications, surveillance, and other applications as well.

  8. Recent advances in bonded composite repair technology for metallic aircraft components

    Energy Technology Data Exchange (ETDEWEB)

    Baker, A.A.; Chester, R.J. [DSTO, Melbourne (Australia). Aeronautical Research Lab.

    1993-12-31

    Advanced fiber composites such as boron/epoxy can be employed as adhesively bonded patches to repair or to reinforce metallic aerospace components. This approach provides many advantages over conventional mechanically fastened metallic patches, including improved fatigue behavior, reduced corrosion and easy conformance to complex aerodynamic contours. Bonded composite repairs have been shown to provide high levels of bond durability under aircraft operating conditions. The recent application of bonded composite repairs to military and civil aircraft is described.

  9. 全封闭碳纤维与高强钢丝复合拉索的弹性模量%Elastic modulus of fully-enclosed composite cable made of CFRP and high-strength steel strand

    Institute of Scientific and Technical Information of China (English)

    陈云钢; 郭正兴; 刘家彬; 常瀚

    2011-01-01

    Coordination mechanism of the fully-enclosed composite cable is investigated, and the requirements that the elastic modulus of the high-strength steel strand and CFRP (carbon fiber reinforced polymer) should be equal is proposed in this paper. Firstly, the relationship between the twist and the elastic modulus of the high-strength steel strand is studied. Then, the calculation formula of the elastic modulus of the high-strength steel strand with 37 strands is derived. Finally, the correctness of the formula is verified by finite element analysis. Test results show that the elastic modulus of CFRP can reach that of high-strength steel strand. It is concluded that the force of the composite cable is distributed in accordance with the axial stiffness of carbon fiber and high-strength steel strand, and the elastic modulus of both CFRP and high-strength steel strand in fully-enclosed composite cable are equal. With the pull of the whole anchorage, the deformation of CFRP in fully-enclosed composite cable is consistent with the deformation of the high-strength steel strand. Equivalence of the elastic modulus determines that the force is distributed in accordance with the ratio of the cross-section of the carbon fiber and the high-strength steel strand, which can ensure the coordination mechanism of the fully-enclosed composite cable. The elastic modulus of the high-strength steel strand is associated with the twist and the torsion angle. With the decrease of the twist and increase of torsion angle, the elastic modulus of the high-strength steel strand decreases.%探讨了全封闭复合拉索的协调工作机理,即要求芯部高强钢丝束与碳纤维筋弹性模量接近或相等;研究了高强钢丝束捻距与弹性模量间的关系;推导了37股高强钢丝束弹性模量的计算表达式,通过有限元分析验证了表达式的正确性.试验表明,碳纤维筋弹性模量可以达到与高强钢丝束的弹性模量相近的要求.结论表明:复

  10. Laminated and pasting CFRP composite strengthening RC beam bending bearing capacity experimental study%叠合与粘贴CFRP复合加固RC简支梁的抗弯承载力试验研究

    Institute of Scientific and Technical Information of China (English)

    李红霞; 郭艳芹; 张雷顺

    2013-01-01

    通过分析叠合与粘贴CFRP复合加固RC简支梁承载力的两大主要影响因素,运用现有计算方法推导得出复合加固RC梁的抗弯承载力计算公式,试验发现:仅粘贴CFRP加固RC梁,虽能有效提高构件承载力,但由于下部受拉储备充足而使上部受压储备相对不足,使构件发生类似超筋梁的脆性破坏,其极限承载力明显低于上部同时有叠合层的RC梁.试验比较发现:所用计算方法得出的计算值与试验值相比偏小,计算公式偏于保守.%Through the analysis of laminated composite of RC beams strengthened with bonded CFRP bearing force of the two major influencing factors, using the existing calculation method of composite strengthening RC beam is derived the formula to calculate the bending bearing capacity, test found that: only paste CFRP strengthened RC beams, can effectively improve the bearing capacity of members, but due to the lower tensile reserves and the upper compression reserve is relatively insufficient, make a component similar over-reinforced beam brittle failure, its ultimate bearing capacity was significantly lower than the upper part while the laminated layer of RC beam. Test comparison showed that:this method calculated value compared with experiment data is small,conservative calculation formula.

  11. Nde for Water Ingression in Composite Radomes on Aircraft

    Science.gov (United States)

    Hsu, David K.; Barnard, Daniel J.; Kite, Adam H.; Kim, Ki-Bok

    2008-02-01

    Aircraft radomes, being an electronic window for the radar, are made of nonconducting composite sandwiches with glass or silica fiber-reinforced facesheet and Nomex honeycomb or foam core. Trapped water or moisture can produce shadow on the image and severely degrade the performance of the radar. To detect water ingression in radomes, the available NDE techniques include x-ray radiography, infrared thermography, and a radome moisture meter that measures the RF power loss caused by the presence of water. In this work we explore the utility of commercially available capacitive sensors with co-planar electrodes that measure the change of the dielectric constant in the fringing field. These capacitive sensors, such as the electronic stud finder and moisture meters for wood, can exploit the large dielectric constant of water and serve as one-sided detectors for water and moisture in radomes. The sensitivities of the various moisture meters were compared in the experimental detection of water introduced into radome panels and water and moisture trapped in retired radomes.

  12. High Energy Wide Area Blunt Impact on Composite Aircraft Structures

    Science.gov (United States)

    DeFrancisci, Gabriela K.

    The largest source of damage to commercial aircraft is caused by accidental contact with ground service equipment (GSE). The cylindrical bumper typically found on GSE distributes the impact load over a large contact area, possibly spanning multiple internal structural elements (frame bays) of a stiffened-skin fuselage. This type of impact can lead to damage that is widespread and difficult to detect visually. To address this problem, monolithic composite panels of various size and complexity have been modeled and tested quasi-statically and dynamically. The experimental observations have established that detectability is dependent on the impact location and immediately-adjacent internal structure of the panel, as well as the impactor geometry and total deformation of the panel. A methodology to model and predict damage caused by wide area blunt impact events was established, which was then applied to more general cases that were not tested in order to better understand the nature of this type of impact event and how it relates to the final damage state and visual detectability.

  13. Development and validation of bonded composite doubler repairs for commercial aircraft.

    Energy Technology Data Exchange (ETDEWEB)

    Roach, Dennis Patrick; Rackow, Kirk A.

    2007-07-01

    A typical aircraft can experience over 2,000 fatigue cycles (cabin pressurizations) and even greater flight hours in a single year. An unavoidable by-product of aircraft use is that crack, impact, and corrosion flaws develop throughout the aircraft's skin and substructure elements. Economic barriers to the purchase of new aircraft have placed even greater demands on efficient and safe repair methods. The use of bonded composite doublers offers the airframe manufacturers and aircraft maintenance facilities a cost effective method to safely extend the lives of their aircraft. Instead of riveting multiple steel or aluminum plates to facilitate an aircraft repair, it is now possible to bond a single Boron-Epoxy composite doubler to the damaged structure. The FAA's Airworthiness Assurance Center at Sandia National Labs (AANC), Boeing, and Federal Express completed a pilot program to validate and introduce composite doubler repair technology to the U.S. commercial aircraft industry. This project focused on repair of DC-10 fuselage structure and its primary goal was to demonstrate routine use of this repair technology using niche applications that streamline the design-to-installation process. As composite doubler repairs gradually appear in the commercial aircraft arena, successful flight operation data is being accumulated. These commercial aircraft repairs are not only demonstrating the engineering and economic advantages of composite doubler technology but they are also establishing the ability of commercial maintenance depots to safely adopt this repair technique. This report presents the array of engineering activities that were completed in order to make this technology available for widespread commercial aircraft use. Focused laboratory testing was conducted to compliment the field data and to address specific issues regarding damage tolerance and flaw growth in composite doubler repairs. Fatigue and strength tests were performed on a simulated wing

  14. Costs and benefits of composite material applications to a civil STOL aircraft

    Science.gov (United States)

    Logan, T. R.

    1974-01-01

    Costs and benefits of advanced composite primary airframe structure were studied to determine cost-effective applications to a civil STOL aircraft designed for introduction in the early 1980 time period. Applications were assessed by comparing costs and weights with a baseline metal aircraft which served as a basis of comparison throughout the study. Costs as well as weights were estimated from specific designs of principal airframe components, thus establishing a cost-data base for the study. Cost effectiveness was judged by an analysis that compared direct operating costs and return on investment of the composite and baseline aircraft. A systems operations analysis was performed to judge effects of the smaller, lighter composite aircraft. It was determined that broad applications of advanced composites to the airframe considered could be cost-effective, but this advantage is strongly influenced by structural configuration and several key cost categories.

  15. Crack growth monitoring at CFRP bond lines

    Science.gov (United States)

    Rahammer, M.; Adebahr, W.; Sachse, R.; Gröninger, S.; Kreutzbruck, M.

    2016-02-01

    With the growing need for lightweight technologies in aerospace and automotive industries, fibre-reinforced plastics, especially carbon-fibre (CFRP), are used with a continuously increasing annual growth rate. A promising joining technique for composites is adhesive bonding. While rivet holes destroy the fibres and cause stress concentration, adhesive bond lines distribute the load evenly. Today bonding is only used in secondary structures due to a lack of knowledge with regard to long-term predictability. In all industries, numerical simulation plays a critical part in the development process of new materials and structures, while it plays a vital role when it comes to CFRP adhesive bondings conducing the predictability of life time and damage tolerance. The critical issue with adhesive bondings is crack growth. In a dynamic tensile stress testing machine we dynamically load bonded CFRP coupon specimen and measure the growth rate of an artificially started crack in order to feed the models with the results. We also investigate the effect of mechanical crack stopping features. For observation of the bond line, we apply two non-contact NDT techniques: Air-coupled ultrasound in slanted transmission mode and active lockin-thermography evaluated at load frequencies. Both methods give promising results for detecting the current crack front location. While the ultrasonic technique provides a slightly higher accuracy, thermography has the advantage of true online monitoring, because the measurements are made while the cyclic load is being applied. The NDT methods are compared to visual inspection of the crack front at the specimen flanks and show high congruence. Furthermore, the effect of crack stopping features within the specimen on the crack growth is investigated. The results show, that not all crack fronts are perfectly horizontal, but all of them eventually come to a halt in the crack stopping feature vicinity.

  16. An Enhanced Vacuum Cure Technique for On-Aircraft Repair of Carbon-Bismaleimide Composites

    Science.gov (United States)

    Rider, Andrew N.; Baker, Alan A.; Wang, Chun H.; Smith, Graeme

    2011-06-01

    Carbon/bismaleimide (BMI) composite is increasingly employed in critical load carrying aircraft structures designed to operate at temperatures approaching 180°C. The high post-cure temperature (above 220°C) required to fully react the BMI resin, however, renders existing on-aircraft prepreg or wet layup repair methods invalid. This paper presents a new on-aircraft repair technique for carbon/BMI composites. The composite prepregs are first warm-staged to improve the ability to evacuate entrapped air. Then the patch is cured in the scarf cavity using the vacuum bag technique, followed by off-aircraft post-cure. The fully cured patch then can be bonded using a structural adhesive.

  17. 基于力学与造价的CFRP-钢组合拉索斜拉桥设计理论%Design of Cable-stayed Bridges with CFRP-steel Composite Stay Cables Based on Mechanical and Economical Behaviors

    Institute of Scientific and Technical Information of China (English)

    熊文; 肖汝诚; CAIC S; 叶见曙

    2012-01-01

    To solve the problem resulting from the low structural stiffness, authors proposed a new design of cable-stayed bridges with composite carbon fiber reinforced polymer (CFRP)-steel stay cables, especially for the cable-stayed bridges with main spans of 1 400 ~ 2 800 m. More specifically, the CFRP stay cables with high strength-to-weight ratio and traditional steel stay cables with high elastic modulus were combined together for application in cable-stayed bridges, which could improve the entire stiffness of bridges. Through a parametric study concerning the equivalent stiffness and economical behavior, three design strategies for the composite cable- stayed bridges were proposed in details: the best equivalent stiffness with equal safety factor, best equivalent stiffness-to-cost ratio with equal safety factor and best equivalent stiffness with equal budget. The design procedure and design chart based on the proposed strategies were also provided. Finally, the feasibility of the proposed cable-stayed bridges was discussed through a case study of a cable-stayed bridge with a main span of 1 400 m. The results indicate that the proposed composite cable-stayed bridges can demonstrate a high equivalent stiffness and can be an excellent selection for the bridges with main spans of 1 400~2 800 m.%针对1400~2800m主跨斜拉桥整体刚度不足的问题,提出一种新型结构方案——碳纤维增强塑料(CFRP)-钢组合拉索斜拉桥。该方案将CFRP斜拉索与传统钢斜拉索同时应用于斜拉桥中,组合2种材料高强轻质及弹性模量高的优点,以:达.到提高斜拉桥整体刚度的设计目的。通过基于力学与造价的参数分析提出该组合拉索斜拉桥的3种设计原则:等安全系数等效刚度最优、等安全系数等效刚度性价比最优、等造价等效刚度最优,并分别给出详细的设计步骤及设计用图。最后,进行了多种方案1400m主跨斜拉桥试设计。结果

  18. Further Evolution of Composite Doubler Aircraft Repairs Through a Focus on Niche Applications

    Energy Technology Data Exchange (ETDEWEB)

    ROACH,DENNIS P.

    2000-07-15

    The number of commercial airframes exceeding twenty years of service continues to grow. A typical aircraft can experience over 2,000 fatigue cycles (cabin pressurizations) and even greater flight hours in a single year. An unavoidable by-product of aircraft use is that crack and corrosion flaws develop throughout the aircraft's skin and substructure elements. Economic barriers to the purchase of new aircraft have created an aging aircraft fleet and placed even greater demands on efficient and safe repair methods. The use of bonded composite doublers offers the airframe manufacturers and aircraft maintenance facilities a cost effective method to safety extend the lives of their aircraft. Instead of riveting multiple steel or aluminum plates to facilitate an aircraft repair, it is now possible to bond a single Boron-Epoxy composite doubler to the damaged structure. The FAA's Airworthiness Assurance Center at Sandia National Labs (AANC) is conducting a program with Boeing and Federal Express to validate and introduce composite doubler repair technology to the US commercial aircraft industry. This project focuses on repair of DC-10 structure and builds on the foundation of the successful L-1011 door corner repair that was completed by the AANC, Lockheed-Martin, and Delta Air Lines. The L-1011 composite doubler repair was installed in 1997 and has not developed any flaws in over three years of service, As a follow-on effort, this DC-1O repair program investigated design, analysis, performance (durability, flaw containment, reliability), installation, and nondestructive inspection issues. Current activities are demonstrating regular use of composite doubler repairs on commercial aircraft. The primary goal of this program is to move the technology into niche applications and to streamline the design-to-installation process. Using the data accumulated to date, the team has designed, analyzed, and developed inspection techniques for an array of composite doubler

  19. A study on the utilization of advanced composites in commercial aircraft wing structure

    Science.gov (United States)

    Watts, D. J.

    1978-01-01

    A study was conducted to define the technology and data needed to support the introduction of advanced composite materials in the wing structure of future production aircraft. The study accomplished the following: (1) definition of acceptance factors, (2) identification of technology issues, (3) evaluation of six candidate wing structures, (4) evaluation of five program options, (5) definition of a composite wing technology development plan, (6) identification of full-scale tests, (7) estimation of program costs for the total development plan, (8) forecast of future utilization of composites in commercial transport aircraft and (9) identification of critical technologies for timely program planning.

  20. Comparison of Requirements for Composite Structures for Aircraft and Space Applications

    Science.gov (United States)

    Raju, Ivatury S.; Elliot, Kenny B.; Hampton, Roy W.; Knight, Norman F., Jr.; Aggarwal, Pravin; Engelstad, Stephen P.; Chang, James B.

    2010-01-01

    In this report, the aircraft and space vehicle requirements for composite structures are compared. It is a valuable exercise to study composite structural design approaches used in the airframe industry and to adopt methodology that is applicable for space vehicles. The missions, environments, analysis methods, analysis validation approaches, testing programs, build quantities, inspection, and maintenance procedures used by the airframe industry, in general, are not transferable to spaceflight hardware. Therefore, while the application of composite design approaches from aircraft and other industries is appealing, many aspects cannot be directly utilized. Nevertheless, experiences and research for composite aircraft structures may be of use in unexpected arenas as space exploration technology develops, and so continued technology exchanges are encouraged.

  1. Flight service evaluation of Kevlar-49/epoxy composite panels in wide-bodied commercial transport aircraft

    Science.gov (United States)

    Stone, R. H.

    1977-01-01

    Kevlar-49 fairing panels, installed as flight service components on three L-1011s, were inspected after three years' service, and found to be performing satisfactorily. There are six Kevlar-49 panels on each aircraft, including sandwich and solid laminate wing-body panels, and 150 C service aft engine fairings. The service history to date indicates that Kevlar-49 epoxy composite materials have satisfactory service characteristics for use in aircraft secondary structure.

  2. Development and utilization of composite honeycomb and solid laminate reference standards for aircraft inspections.

    Energy Technology Data Exchange (ETDEWEB)

    Roach, Dennis Patrick; Rackow, Kirk A.

    2004-06-01

    The FAA's Airworthiness Assurance NDI Validation Center, in conjunction with the Commercial Aircraft Composite Repair Committee, developed a set of composite reference standards to be used in NDT equipment calibration for accomplishment of damage assessment and post-repair inspection of all commercial aircraft composites. In this program, a series of NDI tests on a matrix of composite aircraft structures and prototype reference standards were completed in order to minimize the number of standards needed to carry out composite inspections on aircraft. Two tasks, related to composite laminates and non-metallic composite honeycomb configurations, were addressed. A suite of 64 honeycomb panels, representing the bounding conditions of honeycomb construction on aircraft, was inspected using a wide array of NDI techniques. An analysis of the resulting data determined the variables that play a key role in setting up NDT equipment. This has resulted in a set of minimum honeycomb NDI reference standards that include these key variables. A sequence of subsequent tests determined that this minimum honeycomb reference standard set is able to fully support inspections over the full range of honeycomb construction scenarios found on commercial aircraft. In the solid composite laminate arena, G11 Phenolic was identified as a good generic solid laminate reference standard material. Testing determined matches in key velocity and acoustic impedance properties, as well as, low attenuation relative to carbon laminates. Furthermore, comparisons of resonance testing response curves from the G11 Phenolic NDI reference standard was very similar to the resonance response curves measured on the existing carbon and fiberglass laminates. NDI data shows that this material should work for both pulse-echo (velocity-based) and resonance (acoustic impedance-based) inspections.

  3. Aeroelastic Loads Modeling for Composite Aircraft Design Support

    NARCIS (Netherlands)

    Baluch, H.A.

    2009-01-01

    With regard to the simulation of structural vibrations and consequent aeroelastic loads in aircraft components, the use of elastic axis e.a as reference of vibrations is quite common. The e.a decouples the bending and torsion degrees of freedom (D.o.F) during the dynamic analysis. The use of the e.a

  4. Inter-laminar shear stress in hybrid CFRP/austenitic steel

    Directory of Open Access Journals (Sweden)

    J. Lopes

    2015-01-01

    Full Text Available Bolted joints are the most common solution for joining composite components in aerospace structures. Critical structures such as wing to fuselage joints, or flight control surface fittings use bolted joining techniques. Recent research concluded that higher bearing strengths in composite bolted joints can be achieved by a CFRP/ Titanium hybrid lay-up in the vicinity of the bolted joint. The high costs of titanium motivate a similar research with the more cost competitive austenitic steel. An experimental program was performed in order to compare the apparent inter-laminar shear stress (ILSS of a CFRP reference beam with the ILSS of hybrid CFRP/Steel beams utilizing different surface treatments in the metallic ply. The apparent ILSS was determined by short beam test, a three-point bending test. Finite element models using cohesive elements in the CFRP/Steel interface were built to simulate the short beam test in the reference beam and in the highest interlaminar shear stress hybrid beam. The main parameters for a FEM simulation of inter laminar shear are the cohesive elements damage model and appropriate value for the critical energy release rate. The results show that hybrid CFRP/Steel have a maximum ILSS very similar to the ILSS of the reference beam. Hybrid CFRP/Steel is a competitive solution when compared with the reference beam ILSS. FEM models were able to predict the maximum ILSS in each type of beam.

  5. Analysis of laser ablation dynamics of CFRP in order to reduce heat affected zone

    Science.gov (United States)

    Sato, Yuji; Tsukamoto, Masahiro; Nariyama, Tatsuya; Nakai, Kazuki; Matsuoka, Fumihiro; Takahashi, Kenjiro; Masuno, Shinichiro; Ohkubo, Tomomasa; Nakano, Hitoshi

    2014-03-01

    A carbon fiber reinforced plastic [CFRP], which has high strength, light weight and weather resistance, is attractive material applied for automobile, aircraft and so on. The laser processing of CFRP is one of suitable way to machining tool. However, thermal affected zone was formed at the exposure part, since the heat conduction property of the matrix is different from that of carbon fiber. In this paper, we demonstrated that the CFRP plates were cut with UV nanosecond laser to reduce the heat affected zone. The ablation plume and ablation mass were investigated by laser microscope and ultra-high speed camera. Furthermore, the ablation model was constructed by energy balance, and it was confirmed that the ablation rate was 0.028 μg/ pulse in good agreement with the calculation value of 0.03 μg/ pulse.

  6. Evaluation of Cryogenic CFRP Tank Elements under Pressurized Liquid Hydrogen

    OpenAIRE

    吉田, 誠; Yoshida, Makoto; 須藤, 孝幸; SUDO,Takayuki; 野坂, 正隆; NOSAKA, Masataka

    2001-01-01

    To realize a fully reusable Single-Stage-To-Orbit (SSTO) transportation system, rocket engine performance must be greatly increased and total weight must be drastically reduced. To reduce the weight of the cryogenic tanks which occupy most of the dry weight of the system, it is effective to use lightweight composite materials such as carbon fiber reinforced plastic (CFRP). The goal of the present study was to reduce the weight of the propellant feed system (cryogenic tanks, turbopumps, feed l...

  7. On the role of CFRP reinforcement for wood beams stiffness

    Science.gov (United States)

    Ianasi, A. C.

    2015-11-01

    In recent years, carbon fiber composites have been increasingly used in different ways in reinforcing structural elements. Specifically, the use of composite materials as a reinforcement for wood beams under bending loads requires paying attention to several aspects of the problem such as the number of the composite layers applied on the wood beams. Study consolidation of composites revealed that they are made by bonding fibrous material impregnated with resin on the surface of various elements, to restore or increase the load carrying capacity (bending, cutting, compression or torque) without significant damage of their rigidity. Fibers used in building applications can be fiberglass, aramid or carbon. Items that can be strengthened are concrete, brick, wood, steel and stone, and in terms of structural beams, walls, columns and floors. This paper describes an experimental study which was designed to evaluate the effect of composite material on the stiffness of the wood beams. It proposes a summary of the fundamental principles of analysis of composite materials and the design and use. The type of reinforcement used on the beams is the carbon fiber reinforced polymer (CFRP) sheet and plates and also an epoxy resin for bonding all the elements. Structural epoxy resins remain the primary choice of adhesive to form the bond to fiber-reinforced plastics and are the generally accepted adhesives in bonded CFRP-wood connections. The advantages of using epoxy resin in comparison to common wood-laminating adhesives are their gap-filling qualities and the low clamping pressures that are required to form the bond between carbon fiber plates or sheets and the wood beams. Mechanical tests performed on the reinforced wood beams showed that CFRP materials may produce flexural displacement and lifting increases of the beams. Observations of the experimental load-displacement relationships showed that bending strength increased for wood beams reinforced with CFRP composite plates

  8. Analysis of nonlinear deformations and damage in CFRP textile laminates

    Science.gov (United States)

    Ullah, H.; Harland, A. R.; Lucas, T.; Price, D.; Silberschmidt, V. V.

    2011-07-01

    Carbon fibre-reinforced polymer (CFRP) textile composites are widely used in aerospace, automotive and construction components and structures thanks to their relatively low production costs, higher delamination and impact strength. They can also be used in various products in sports industry. These products are usually exposed to different in-service conditions such as large bending deformation and multiple impacts. Composite materials usually demonstrate multiple modes of damage and fracture due to their heterogeneity and microstructure, in contrast to more traditional homogeneous structural materials like metals and alloys. Damage evolution affects both their in-service properties and performance that can deteriorate with time. These damage modes need adequate means of analysis and investigation, the major approaches being experimental characterisation, numerical simulations and microtomography analysis. This research deals with a deformation behaviour and damage in composite laminates linked to their quasi-static bending. Experimental tests are carried out to characterise the behaviour of woven CFRP material under large-deflection bending. Two-dimensional finite element (FE) models are implemented in the commercial code Abaqus/Explicit to study the deformation behaviour and damage in woven CFRP laminates. Multiple layers of bilinear cohesive-zone elements are employed to model the onset and progression of inter-ply delamination process. X-ray Micro-Computed Tomography (MicroCT) analysis is carried out to investigate internal damage mechanisms such as cracking and delaminations. The obtained results of simulations are in agreement with experimental data and MicroCT scans.

  9. Full-Scale Structural and NDI Validation Tests of Bonded Composite Doublers for Commercial Aircraft Applications

    Energy Technology Data Exchange (ETDEWEB)

    Roach, D.; Walkington, P.

    1999-02-01

    Composite doublers, or repair patches, provide an innovative repair technique which can enhance the way aircraft are maintained. Instead of riveting multiple steel or aluminum plates to facilitate an aircraft repair, it is possible to bond a single Boron-Epoxy composite doubler to the damaged structure. Most of the concerns surrounding composite doubler technology pertain to long-term survivability, especially in the presence of non-optimum installations, and the validation of appropriate inspection procedures. This report focuses on a series of full-scale structural and nondestructive inspection (NDI) tests that were conducted to investigate the performance of Boron-Epoxy composite doublers. Full-scale tests were conducted on fuselage panels cut from retired aircraft. These full-scale tests studied stress reductions, crack mitigation, and load transfer capabilities of composite doublers using simulated flight conditions of cabin pressure and axial stress. Also, structures which modeled key aspects of aircraft structure repairs were subjected to extreme tension, shear and bending loads to examine the composite laminate's resistance to disbond and delamination flaws. Several of the structures were loaded to failure in order to determine doubler design margins. Nondestructive inspections were conducted throughout the test series in order to validate appropriate techniques on actual aircraft structure. The test results showed that a properly designed and installed composite doubler is able to enhance fatigue life, transfer load away from damaged structure, and avoid the introduction of new stress risers (i.e. eliminate global reduction in the fatigue life of the structure). Comparisons with test data obtained prior to the doubler installation revealed that stresses in the parent material can be reduced 30%--60% through the use of the composite doubler. Tests to failure demonstrated that the bondline is able to transfer plastic strains into the doubler and that

  10. Design and Analysis of Composite Propeller Blade for Aircraft

    OpenAIRE

    Madhusudhan BM; Dr P.V Srihari

    2014-01-01

    Fiber reinforced composites is used for twin blade propeller because of its high strength, low temperature applications. Fiber has to be oriented in the loading direction while designing the composite propeller blade. The blade geometry and design are more complex involving many controlling parameters. In the present work a methodology to design a composite propeller to analyze its strength and deformation using ANSYS software. The weight of the composite blade is reduced comp...

  11. Study on utilization of advanced composites in commercial aircraft wing structures. Volume 1: Executive summary

    Science.gov (United States)

    Sakata, I. F.; Ostrom, R. B.; Cardinale, S. V.

    1978-01-01

    The effort required by commercial transport manufacturers to accomplish the transition from current construction materials and practices to extensive use of composites in aircraft wings was investigated. The engineering and manufacturing disciplines which normally participate in the design, development, and production of an aircraft were employed to ensure that all of the factors that would enter a decision to commit to production of a composite wing structure were addressed. A conceptual design of an advanced technology reduced energy aircraft provided the framework for identifying and investigating unique design aspects. A plan development effort defined the essential technology needs and formulated approaches for effecting the required wing development. The wing development program plans, resource needs, and recommendations are summarized.

  12. Structural health monitoring and impact detection for primary aircraft structures

    Science.gov (United States)

    Kosters, Eric; van Els, Thomas J.

    2010-04-01

    The increasing use of thermoplastic carbon fiber-reinforced plastic (CFRP) materials in the aerospace industry for primary aircraft structures, such as wing leading-edge surfaces and fuselage sections, has led to rapid growth in the field of structural health monitoring (SHM). Impact, vibration, and load can all cause failure, such as delamination and matrix cracking, in composite materials. Moreover, the internal material damage can occur without being visible to the human eye, making inspection of and clear insight into structural integrity difficult using currently available evaluation methods. Here, we describe the detection of impact and its localization in materials and structures by high-speed interrogation of multiple-fiber Bragg grating (FBG) sensors mounted on a composite aircraft component.

  13. Development and validation of nondestructive inspection techniques for composite doubler repairs on commercial aircraft

    Energy Technology Data Exchange (ETDEWEB)

    Roach, D.; Walkington, P.

    1998-05-01

    Composite doublers, or repair patches, provide an innovative repair technique which can enhance the way aircraft are maintained. Instead of riveting multiple steel or aluminum plates to facilitate an aircraft repair, it is possible to bond a single boron-epoxy composite doubler to the damaged structure. In order for the use of composite doublers to achieve widespread use in the civil aviation industry, it is imperative that methods be developed which can quickly and reliably assess the integrity of the doubler. In this study, a specific composite application was chosen on an L-1011 aircraft in order to focus the tasks on application and operation issues. Primary among inspection requirements for these doublers is the identification of disbonds, between the composite laminate and aluminum parent material, and delaminations in the composite laminate. Surveillance of cracks or corrosion in the parent aluminum material beneath the doubler is also a concern. No single nondestructive inspection (NDI) method can inspect for every flaw type, therefore it is important to be aware of available NDI techniques and to properly address their capabilities and limitations. A series of NDI tests were conducted on laboratory test structures and on full-scale aircraft fuselage sections. Specific challenges, unique to bonded composite doubler applications, were highlighted. An array of conventional and advanced NDI techniques were evaluated. Flaw detection sensitivity studies were conducted on applicable eddy current, ultrasonic, X-ray and thermography based devices. The application of these NDI techniques to composite doublers and the results from test specimens, which were loaded to provide a changing flaw profile, are presented in this report. It was found that a team of these techniques can identify flaws in composite doubler installations well before they reach critical size.

  14. Probabilistic Remaining Useful Life Prediction of Composite Aircraft Components Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A Probabilistic Fatigue Damage Assessment Network (PFDAN) toolkit for Abaqus will be developed for probabilistic life management of a laminated composite structure...

  15. Probabilistic Remaining Useful Life Prediction of Composite Aircraft Components Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A composite fatigue damage assessment and risk informed prognosis toolkit will be developed by enhancing and integrating existing solution modules within a...

  16. Study on utilization of advanced composites in commercial aircraft wing structures, volume 2

    Science.gov (United States)

    Sakata, I. F.; Ostrom, R. B.

    1978-01-01

    A plan is defined for a composite wing development effort which will assist commercial transport manufacturers in reaching a level of technology readiness where the utilization of composite wing structure is a cost competitive option for a new aircraft production plan. The recommended development effort consists of two programs: a joint government/industry material development program and a wing structure development program. Both programs are described in detail.

  17. HTS SQUIDs for the nondestructive evaluation of composite structures

    Energy Technology Data Exchange (ETDEWEB)

    Carr, Chris; Graham, David; Macfarlane, John C; Donaldson, Gordon B [Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

    2003-12-01

    While LTS and HTS SQUIDs have successfully been applied in the detection of flaws in aircraft grade aluminium structures for well over a decade, interest has recently spread to a type of new material, namely composites. One example, carbon fibre reinforced polymer (CFRP), is increasingly being favoured by the aircraft industry because of its strength to weight ratio and the fact that it is corrosion-resistant. Material and defect characterization using SQUIDs is still at an early stage, but due to expected rapid expansion in the use of such materials, there is ample scope for the application of HTS SQUIDs. Here we have applied HTS SQUID single-layer gradiometers to investigate artificially created defects in CFRP samples.

  18. Spiral Passive Electromagnetic Sensor (SPES) for composite structural changes in aircraft structures

    Science.gov (United States)

    Iervolino, Onorio; Meo, Michele

    2016-04-01

    A major goal of structural health monitoring (SHM) is to provide accurate and responsive detection and monitoring of flaws. This research work reports an investigation of SPES sensors for damage detection, investigating different sensor sizes and how they affect the sensor's signal. A sensor able to monitor structural change that can be remotely interrogated and does not need a power supply is presented in this work. The SPES-sensor presents the great advantage of monitoring conductive and non-conductive structures such as fiberglass-reinforced composites (FRC) and carbon fiber-reinforced polymers (CFRP). Any phenomena that affect the magnetic field of the SPES can be detected and monitored. A study was conducted to investigate the capability of sensor to give information on structural changes, simulated by the presence of an external mass placed in the proximity of sensor. Effect of different positions of the SPES within the sample, and how to extend the area of inspection using multiple sensors was investigated. The sensor was tested embedded in the samples, simulating the structural change on both sides of the sample. In both configurations the sensor described herein demonstrated a great potential to monitor structural changes.

  19. Cradle-to-Grave Monitoring of Composite Aircraft Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NextGen is proposing a simple yet powerful damage identification technique for advanced composite structures. We propose to develop a damage index based on...

  20. Effect of CFRP Plate Location on Flexural Behavior of RC Beam Strengthened with CFRP Plate

    Directory of Open Access Journals (Sweden)

    Mohammed Jassam Mohammed Altaee

    2011-01-01

    Full Text Available Location of CFRP plate, as a mode of failure, is one of the major limitations when using externally bonded carbon fiber reinforced polymer (CFRP plates in strengthening of RC beams. In this work, mode of CFRP plate location was analytically investigated. A non-linear finite element model is proposed in order to analyze experimental data presented by David et.al.[1]. The eight node brick element (SOLID65 as denoted in ANSYS is used to model reinforced concrete and four node shell element (SHELL41 is used to represented CFRP plate, bond between concrete and CFRP plate represented by interface element (CONTAC52. The results obtained from analytical study explained that the best location of CFRP is at lower edges of concrete beam.

  1. Cutting and drilling of carbon fiber reinforced plastics (CFRP) by 70W short pulse nanosecond laser

    Science.gov (United States)

    Jaeschke, Peter; Stolberg, Klaus; Bastick, Stefan; Ziolkowski, Ewa; Roehner, Markus; Suttmann, Oliver; Overmeyer, Ludger

    2014-02-01

    Continuous carbon fibre reinforced plastics (CFRP) are recognized as having a significant lightweight construction potential for a wide variety of industrial applications. However, a today`s barrier for a comprehensive dissemination of CFRP structures is the lack of economic, quick and reliable manufacture processes, e.g. the cutting and drilling steps. In this paper, the capability of using pulsed disk lasers in CFRP machining is discussed. In CFRP processing with NIR lasers, carbon fibers show excellent optical absorption and heat dissipation, contrary to the plastics matrix. Therefore heat dissipation away from the laser focus into the material is driven by heat conduction of the fibres. The matrix is heated indirectly by heat transfer from the fibres. To cut CFRP, it is required to reach the melting temperature for thermoplastic matrix materials or the disintegration temperature for thermoset systems as well as the sublimation temperature of the reinforcing fibers simultaneously. One solution for this problem is to use short pulse nanosecond lasers. We have investigated CFRP cutting and drilling with such a laser (max. 7 mJ @ 10 kHz, 30 ns). This laser offers the opportunity of wide range parameter tuning for systematic process optimization. By applying drilling and cutting operations based on galvanometer scanning techniques in multi-cycle mode, excellent surface and edge characteristics in terms of delamination-free and intact fiber-matrix interface were achieved. The results indicate that nanosecond disk laser machining could consequently be a suitable tool for the automotive and aircraft industry for cutting and drilling steps.

  2. Certification of Discontinuous Composite Material Forms for Aircraft Structures

    Science.gov (United States)

    Arce, Michael Roger

    New, high performance chopped, discontinuous, or short fiber composites (DFCs), DFCs, such as HexMC and Lytex, made by compression molding of randomly oriented pre-impregnated unidirectional tape, can be formed into complex geometry while retaining mechanical properties suitable for structural use. These DFCs provide the performance benefits of Continuous Fiber Composites (CFCs) in form factors that were previously unavailable. These materials demonstrate some notably different properties from continuous fiber composites, especially with respect to damage tolerance and failure behavior. These behaviors are not very well understood, and fundamental research efforts are ongoing to better characterize the material and to ease certification for future uses. Despite this, these new DFCs show such promise that they are already in service in the aerospace industry, for instance in the Boeing 787. Unfortunately, the relative novelty of these parts means that they needed to be certified by “point design”, an excess of physical testing, rather than by a mix of physical testing and finite element analysis, which would be the case for CFCs or metals. In this study, one particular approach to characterizing both linear-elastic and failure behaviors are considered. The Stochastic Laminate Analogy, which represents a novel approach to modeling DFCs, and its combination with a Ply Discount scheme. Owing to limited available computational resources, only preliminary results are available, but those results are quite promising and warrant further investigation.

  3. Federal Aviation Administration (FAA airworthiness certification for ceramic matrix composite components in civil aircraft systems

    Directory of Open Access Journals (Sweden)

    Gonczy Stephen T.

    2015-01-01

    Full Text Available Ceramic matrix composites (CMCs are being designed and developed for engine and exhaust components in commercial aviation, because they offer higher temperature capabilities, weight savings, and improved durability compared to metals. The United States Federal Aviation Administration (FAA issues and enforces regulations and minimum standards covering the safe manufacture, operation, and maintenance of civil aircraft. As new materials, these ceramic composite components will have to meet the certification regulations of the FAA for “airworthiness”. The FAA certification process is defined in the Federal Aviation Regulations (Title 14 of the Code of Federal Regulations, FAA policy statements, orders, advisory circulars, technical standard orders, and FAA airworthiness directives. These regulations and documents provide the fundamental requirements and guidelines for design, testing, manufacture, quality assurance, registration, operation, inspection, maintenance, and repair of aircraft systems and parts. For metallic parts in aircraft, the FAA certification and compliance process is well-established for type and airworthiness certification, using ASTM and SAE standards, the MMPDS data handbook, and FAA advisory circulars. In a similar manner for polymer matrix composites (PMC, the PMC industry and the FAA have jointly developed and are refining parallel guidelines for polymer matrix composites (PMCs, using guidance in FAA circulars and the CMH-17 PMC handbook. These documents discuss design methods and codes, material testing, property data development, life/durability assessment, production processes, QA procedures, inspection methods, operational limits, and repairs for PMCs. For ceramic composites, the FAA and the CMC and aerospace community are working together (primarily through the CMH-17 CMC handbook to define and codify key design, production, and regulatory issues that have to be addressed in the certification of CMC components in

  4. Damage criticality and inspection concerns of composite-metallic aircraft structures under blunt impact

    Science.gov (United States)

    Zou, D.; Haack, C.; Bishop, P.; Bezabeh, A.

    2015-04-01

    Composite aircraft structures such as fuselage and wings are subject to impact from many sources. Ground service equipment (GSE) vehicles are regarded as realistic sources of blunt impact damage, where the protective soft rubber is used. With the use of composite materials, blunt impact damage is of special interest, since potential significant structural damage may be barely visible or invisible on the structure's outer surface. Such impact can result in local or non-local damage, in terms of internal delamination in skin, interfacial delamination between stiffeners and skin, and fracture of internal reinforced component such as stringers and frames. The consequences of these events result in aircraft damage, delays, and financial cost to the industry. Therefore, it is necessary to understand the criticality of damage under this impact and provide reliable recommendations for safety and inspection technologies. This investigation concerns a composite-metallic 4-hat-stiffened and 5-frame panel, designed to represent a fuselage structure panel generic to the new generation of composite aircraft. The test fixtures were developed based on the correlation between finite element analyses of the panel model and the barrel model. Three static tests at certain amount of impact energy were performed, in order to improve the understanding of the influence of the variation in shear ties, and the added rotational stiffness. The results of this research demonstrated low velocity high mass impacts on composite aircraft fuselages beyond 82.1 kN of impact load, which may cause extensive internal structural damage without clear visual detectability on the external skin surface.

  5. Fibre Optic Sensors for Structural Health Monitoring of Aircraft Composite Structures: Recent Advances and Applications

    Directory of Open Access Journals (Sweden)

    Raffaella Di Sante

    2015-07-01

    Full Text Available In-service structural health monitoring of composite aircraft structures plays a key role in the assessment of their performance and integrity. In recent years, Fibre Optic Sensors (FOS have proved to be a potentially excellent technique for real-time in-situ monitoring of these structures due to their numerous advantages, such as immunity to electromagnetic interference, small size, light weight, durability, and high bandwidth, which allows a great number of sensors to operate in the same system, and the possibility to be integrated within the material. However, more effort is still needed to bring the technology to a fully mature readiness level. In this paper, recent research and applications in structural health monitoring of composite aircraft structures using FOS have been critically reviewed, considering both the multi-point and distributed sensing techniques.

  6. Fibre Optic Sensors for Structural Health Monitoring of Aircraft Composite Structures: Recent Advances and Applications.

    Science.gov (United States)

    Di Sante, Raffaella

    2015-01-01

    In-service structural health monitoring of composite aircraft structures plays a key role in the assessment of their performance and integrity. In recent years, Fibre Optic Sensors (FOS) have proved to be a potentially excellent technique for real-time in-situ monitoring of these structures due to their numerous advantages, such as immunity to electromagnetic interference, small size, light weight, durability, and high bandwidth, which allows a great number of sensors to operate in the same system, and the possibility to be integrated within the material. However, more effort is still needed to bring the technology to a fully mature readiness level. In this paper, recent research and applications in structural health monitoring of composite aircraft structures using FOS have been critically reviewed, considering both the multi-point and distributed sensing techniques. PMID:26263987

  7. Rheological behavior of composites based on carbon fibers recycled from aircraft waste

    OpenAIRE

    Marcaníková, Lucie; Hausnerová, Berenika; Kitano, Takeshi

    2009-01-01

    Rheological investigation of composite materials prepared from the recycled aircraft waste materials based on thermoset (epoxy/resin) matrix and long carbon fibers (CF) is presented with the aim of their utilization in consumer industry applications. The carbon fibers recovered via thermal process of pyrolysis were cut into about 150 pm length and melt mixed with thermoplastic matrices based on polypropylene (PP) and polyamide 6 (PA) and various modifiers - ethylene-ethyl acrylate-maleic anhy...

  8. Advanced composite elevator for Boeing 727 aircraft. Volume 1: Technical summary

    Science.gov (United States)

    Chovil, D. V.; Harvey, S. T.; Mccarty, J. E.; Desper, O. E.; Jamison, E. S.; Syder, H.

    1981-01-01

    The design, development, analysis, and testing activities and results that were required to produce five and one-half shipsets of advanced composite elevators for Boeing 727 aircraft are summarized. During the preliminary design period, alternative concepts were developed. After selection of the best design, detail design and basic configuration improvements were evaluated. Five and one-half shipsets were manufactured. All program goals (except competitive cost demonstration) were accomplished when our design met or exceeded all requirements, criteria, and objectives.

  9. Recent Development in Ultrasonic Guided Waves for Aircraft and Composite Materials

    Energy Technology Data Exchange (ETDEWEB)

    Rose, Joseph L. [Pennsylvania State University, Pennsylvania (United States)

    2009-12-15

    Emphasis in the paper is placed on describing guided wave successes and challenges for applications in aircraft and composite materials inspection. Guided wave imaging methods discussed includes line of sight, tomography, guided wave C-scan, phased array, and ultrasonic vibration methods. Applications outlined encircles lap splice, bonded repair patch, fuselage corrosion, water loaded structures, delamination, and ice detection and de-icing of various structures.

  10. Fibre Optic Sensors for Structural Health Monitoring of Aircraft Composite Structures: Recent Advances and Applications

    OpenAIRE

    Raffaella Di Sante

    2015-01-01

    In-service structural health monitoring of composite aircraft structures plays a key role in the assessment of their performance and integrity. In recent years, Fibre Optic Sensors (FOS) have proved to be a potentially excellent technique for real-time in-situ monitoring of these structures due to their numerous advantages, such as immunity to electromagnetic interference, small size, light weight, durability, and high bandwidth, which allows a great number of sensors to operate in the same s...

  11. Full-scale testing, production and cost analysis data for the advanced composite stabilizer for Boeing 737 aircraft, volume 2

    Science.gov (United States)

    Aniversario, R. B.; Harvey, S. T.; Mccarty, J. E.; Parson, J. T.; Peterson, D. C.; Pritchett, L. D.; Wilson, D. R.; Wogulis, E. R.

    1982-01-01

    The development, testing, production activities, and associated costs that were required to produce five-and-one-half advanced-composite stabilizer shipsets for Boeing 737 aircraft are defined and discussed.

  12. Evaluation of Seismic Behaviors of Partially Deteriorated Reinforced Concrete Circular Columns Retrofitted with CFRP

    Directory of Open Access Journals (Sweden)

    Dongxu Hou

    2014-01-01

    Full Text Available Deficiency of the concrete strength in some regions of reinforced concrete (RC columns in practice may weaken the seismic behaviors of columns. Its effects on RC columns should be well understood. This paper aims to investigate the influences of deteriorated segment on the seismic behaviors of partially deteriorated RC columns and attempts to recover the seismic behaviors of partially deteriorated columns with Carbon Fiber Reinforced Polymer (CFRP composites. A finite element analysis was carried out to simulate the seismic behaviors of CFRP-confined partially deteriorated RC columns. The numerical results were verified by the laboratory tests of six specimens. Based on the finite element results, the failure location of partially deteriorated columns in an earthquake was predicted, and the effectiveness of CFRP retrofitted on partially deteriorated columns was evaluated.

  13. Low-velocity impact damage characterization of carbon fiber reinforced polymer (CFRP) using infrared thermography

    Science.gov (United States)

    Li, Yin; Zhang, Wei; Yang, Zheng-wei; Zhang, Jin-yu; Tao, Sheng-jie

    2016-05-01

    Carbon fiber reinforced polymer (CFRP) after low-velocity impact is detected using infrared thermography, and different damages in the impacted composites are analyzed in the thermal maps. The thermal conductivity under pulse stimulation, frictional heating and thermal conductivity under ultrasonic stimulation of CFRP containing low-velocity impact damage are simulated using numerical simulation method. Then, the specimens successively exposed to the low-velocity impact are respectively detected using the pulse infrared thermography and ultrasonic infrared thermography. Through the numerical simulation and experimental investigation, the results obtained show that the combination of the above two detection methods can greatly improve the capability for detecting and evaluating the impact damage in CFRP. Different damages correspond to different infrared thermal images. The delamination damage, matrix cracking and fiber breakage are characterized as the block-shape hot spot, line-shape hot spot,

  14. X-ray inspection of composite materials for aircraft structures using detectors of Medipix type

    Science.gov (United States)

    Jandejsek, I.; Jakubek, J.; Jakubek, M.; Prucha, P.; Krejci, F.; Soukup, P.; Turecek, D.; Vavrik, D.; Zemlicka, J.

    2014-05-01

    This work presents an overview of promising X-ray imaging techniques employed for non-destructive defectoscopy inspections of composite materials intended for the Aircraft industry. The major emphasis is placed on non-tomographic imaging techniques which do not require demanding spatial and time measurement conditions. Imaging methods for defects visualisation, delamination detection and porosity measurement of various composite materials such as carbon fibre reinforced polymers and honeycomb sendwiches are proposed. We make use of the new large area WidePix X-ray imaging camera assembled from up to 100 edgeless Medipix type detectors which is highly suitable for this type of measurements.

  15. Damage in woven CFRP laminates subjected to low velocity impacts

    Science.gov (United States)

    Ullah, H.; Abdel-Wahab, A. A.; Harland, A. R.; Silberschmidt, V. V.

    2012-08-01

    Carbon fabric-reinforced polymer (CFRP) composites used in sports products can be exposed to different in-service conditions such as large dynamic bending deformations caused by impact loading. Composite materials subjected to such loads demonstrate various damage modes such as matrix cracking, delamination and, ultimately, fabric fracture. Damage evolution in these materials affects both their in-service properties and performance that can deteriorate with time. These processes need adequate means of analysis and investigation, the major approaches being experimental characterisation and non-destructive examination of internal damage in composite laminates. This research deals with a deformation behaviour and damage in woven composite laminates due to low-velocity dynamic out-of-plane bending. Experimental tests are carried out to characterise the behaviour of such laminates under large-deflection dynamic bending in un-notched specimens in Izod tests using a Resil Impactor. A series of low-velocity impact tests is carried out at various levels of impact energy to assess the energy absorbed and force-time response of CFRP laminates. X-ray micro computed tomography (micro-CT) is used to investigate material damage modes in the impacted specimens. X-ray tomographs revealed that through-thickness matrix cracking, inter-ply delamination and intra-ply delamination, such as tow debonding and fabric fracture, were the prominent damage modes.

  16. Analytical and experimental investigation of aircraft metal structures reinforced with filamentary composites. Phase 3: Major component development

    Science.gov (United States)

    Bryson, L. L.; Mccarty, J. E.

    1973-01-01

    Analytical and experimental investigations, performed to establish the feasibility of reinforcing metal aircraft structures with advanced filamentary composites, are reported. Aluminum-boron-epoxy and titanium-boron-epoxy were used in the design and manufacture of three major structural components. The components were representative of subsonic aircraft fuselage and window belt panels and supersonic aircraft compression panels. Both unidirectional and multidirectional reinforcement concepts were employed. Blade penetration, axial compression, and inplane shear tests were conducted. Composite reinforced structural components designed to realistic airframe structural criteria demonstrated the potential for significant weight savings while maintaining strength, stability, and damage containment properties of all metal components designed to meet the same criteria.

  17. Hygromechanical behaviour of CFRP under cyclic humidity loadings

    CERN Document Server

    Hauviller, Claude

    2001-01-01

    Stable lightweight structures are key issues in the design and construction of the LHC high precision particle detectors. This paper presents the results of long term measurements performed on plates manufactured in Carbon Fibre Reinforced Plastics (CFRP), material selected for these structures, subjected to cyclic humidity loadings. Test procedures are detailed; results on moisture absorption are described together with the related displacement measurements. These results indicate that cycling composites in the operating conditions of the LHC trackers does not provoke any major internal damage.

  18. CFRP strengthening of concrete beams - testing in sub-zero temperature

    DEFF Research Database (Denmark)

    Täljsten, Björn; Carolin, A.

    2007-01-01

    Strengthening structures with epoxy bonded Carbon Fibre-Reinforced Polymer (CFRP) plates and sheets are today a well-known and over the world common used method to improve a structure performance. The composite materials used for strengthening are very light and easy to handle,. have good...

  19. Energy Finite Element Analysis Developments for Vibration Analysis of Composite Aircraft Structures

    Science.gov (United States)

    Vlahopoulos, Nickolas; Schiller, Noah H.

    2011-01-01

    The Energy Finite Element Analysis (EFEA) has been utilized successfully for modeling complex structural-acoustic systems with isotropic structural material properties. In this paper, a formulation for modeling structures made out of composite materials is presented. An approach based on spectral finite element analysis is utilized first for developing the equivalent material properties for the composite material. These equivalent properties are employed in the EFEA governing differential equations for representing the composite materials and deriving the element level matrices. The power transmission characteristics at connections between members made out of non-isotropic composite material are considered for deriving suitable power transmission coefficients at junctions of interconnected members. These coefficients are utilized for computing the joint matrix that is needed to assemble the global system of EFEA equations. The global system of EFEA equations is solved numerically and the vibration levels within the entire system can be computed. The new EFEA formulation for modeling composite laminate structures is validated through comparison to test data collected from a representative composite aircraft fuselage that is made out of a composite outer shell and composite frames and stiffeners. NASA Langley constructed the composite cylinder and conducted the test measurements utilized in this work.

  20. Flight service evaluation of Kevlar-49 epoxy composite panels in wide-bodies commercial transport aircraft

    Science.gov (United States)

    Stone, R. H.

    1983-01-01

    Kevlar-49 fairing panels, installed as flight service components on three L-1011s, were inspected after 9 years of service. There are six Kevlar-49 panels on each aircraft: a left hand and right hand set of a wing body sandwich fairing; a solid laminate under wing fillet panel; and a 422 K (300 F) service aft engine fairing. The fairings have accumulated a total of 70,000 hours, with one ship set having over 24,000 hours service. The Kevlar-49 components were found to be performing satisfactorily in service with no major problems, or any condition requiring corrective action. The only defects noted were minor impact damage, a few minor disbonds and a minor degree of fastener hole fraying and elongation. These are for the most part comparable to damage noted on fiberglass fairings. The service history to date indicates that Kevlar-49 epoxy composite materials have satisfactory service characteristics for use in aircraft secondary structure.

  1. Effect of Thermal Distress on Residual Behavior of CFRP-Strengthened Steel Beams Including Periodic Unbonded Zones

    Directory of Open Access Journals (Sweden)

    Isamu Yoshitake

    2015-11-01

    Full Text Available This paper presents the residual behavior of wide-flange steel beams strengthened with high-modulus carbon fiber-reinforced polymer (CFRP laminates subjected to thermal loading. Because the coefficients of thermal expansion of the steel and the CFRP are different, temperature-induced distress may take place along their interface. Periodic unbonded zones are considered to represent local interfacial damage. Five test categories are designed depending on the size of the unbonded zones from 10 to 50 mm, and corresponding beams are loaded until failure occurs after exposing to a cyclic temperature range of ΔT = 25 °C (−10 to 15 °C up to 84 days. The composite action between the CFRP and the steel substrate is preserved until yielding of the beams happens, regardless of the thermal cycling and periodic unbonded zones. The initiation and progression of CFRP debonding become apparent as the beams are further loaded, particularly at geometric discontinuities in the vicinity of the unbonded zones along the interface. A simple analytical model is employed to predict the interfacial stress of the strengthened beams. A threshold temperature difference of ΔT = 30 °C is estimated for the initiation and progression of CFRP debonding. Multiple debonding-progression stages in conjunction with the extent of thermal distress appear to exist. It is recommended that high-modulus CFRP be restrictively used for strengthening steel members potentially exposed to a wide temperature variation range.

  2. Optical Sensing of the Fatigue Damage State of CFRP under Realistic Aeronautical Load Sequences

    Directory of Open Access Journals (Sweden)

    Pablo Zuluaga-Ramírez

    2015-03-01

    Full Text Available We present an optical sensing methodology to estimate the fatigue damage state of structures made of carbon fiber reinforced polymer (CFRP, by measuring variations on the surface roughness. Variable amplitude loads (VAL, which represent realistic loads during aeronautical missions of fighter aircraft (FALSTAFF have been applied to coupons until failure. Stiffness degradation and surface roughness variations have been measured during the life of the coupons obtaining a Pearson correlation of 0.75 between both variables. The data were compared with a previous study for Constant Amplitude Load (CAL obtaining similar results. Conclusions suggest that the surface roughness measured in strategic zones is a useful technique for structural health monitoring of CFRP structures, and that it is independent of the type of load applied. Surface roughness can be measured in the field by optical techniques such as speckle, confocal perfilometers and interferometry, among others.

  3. Experimental and Numerical Investigation of Wide Area Blunt Impact Damage to Composite Aircraft Structures

    Science.gov (United States)

    Chen, Zhi Ming

    Due to their high performance and weight efficiency, carbon fiber composites are increasingly being used in aircraft primary structure applications. Exposed composite structures (e.g., fuselage lower body) are susceptible accidental impacts by ground service equipment (GSE). The very high mass (over 10,000 kg) of GSE impact can involve high energy (over 1000 J) and thus can induce significant internal damage. Furthermore, the large contact area potentially involved with GSE impact can create significant internal delamination and fiber failure without leaving exterior-visible signs that any damage has occurred. The objectives of the research described herein are to: (1) conduct experimental investigation into the composite aircraft damage caused by GSE impact, (2) examine the small-scale failure modes in focused, element-level studies, (3) establish a finite element modeling methodology involving detailed simulation capability that is validated via small-scale tests, and (4) apply these modeling capabilities to accurately predict full-scale structural behavior without adjustment (e.g., tuning) of modeling input parameters.

  4. High-Temperature, Lightweight, Self-Healing Ceramic Composites for Aircraft Engine Applications

    Science.gov (United States)

    Raj, Sai V.; Bhatt, Ramkrishna

    2013-01-01

    The use of reliable, high-temperature, lightweight materials in the manufacture of aircraft engines is expected to result in lower fossil and biofuel consumption, thereby leading to cost savings and lower carbon emissions due to air travel. Although nickel-based superalloy blades and vanes have been successfully used in aircraft engines for several decades, there has been an increased effort to develop high-temperature, lightweight, creep-resistant substitute materials under various NASA programs over the last two decades. As a result, there has been a great deal of interest in developing SiC/SiC ceramic matrix composites (CMCs) due to their higher damage tolerance compared to monolithic ceramics. Current-generation SiC/SiC ceramic matrix composites rely almost entirely on the SiC fibers to carry the load, owing to the premature cracking of the matrix during loading. Thus, the high-temperature usefulness of these CMCs falls well below their theoretical capabilities. The objective of this work is to develop a new class of high-temperature, lightweight, self-healing, SiC fiber-reinforced, engineered matrix ceramic composites.

  5. Residual stress alleviation of aircraft metal structures reinforced with filamentary composites

    Science.gov (United States)

    Kelly, J. B.; June, R. R.

    1973-01-01

    Methods to eliminate or reduce residual stresses in aircraft metal structures reinforced by filamentary composites are discussed. Residual stress level reductions were achieved by modifying the manufacturing procedures used during adhesive bonding. The residual stress alleviation techniques involved various forms of mechanical constraint which were applied to the components during bonding. Nine methods were evaluated, covering a wide range in complexity. All methods investigated during the program affected the residual stress level. In general, residual stresses were reduced by 70 percent or more from the stress level produced by conventional adhesive bonding procedures.

  6. Advanced composites structural concepts and materials technologies for primary aircraft structures: Design/manufacturing concept assessment

    Science.gov (United States)

    Chu, Robert L.; Bayha, Tom D.; Davis, HU; Ingram, J. ED; Shukla, Jay G.

    1992-01-01

    Composite Wing and Fuselage Structural Design/Manufacturing Concepts have been developed and evaluated. Trade studies were performed to determine how well the concepts satisfy the program goals of 25 percent cost savings, 40 percent weight savings with aircraft resizing, and 50 percent part count reduction as compared to the aluminum Lockheed L-1011 baseline. The concepts developed using emerging technologies such as large scale resin transfer molding (RTM), automatic tow placed (ATP), braiding, out-of-autoclave and automated manufacturing processes for both thermoset and thermoplastic materials were evaluated for possible application in the design concepts. Trade studies were used to determine which concepts carry into the detailed design development subtask.

  7. Evaluation of energy absorption of new concepts of aircraft composite subfloor intersections

    Science.gov (United States)

    Jones, Lisa E.; Carden, Huey D.

    1989-01-01

    Forty-one composite aircraft subfloor intersection specimens were tested to determine the effects of geometry and material on the energy absorbing behavior, failure characteristics, and post-crush structural integrity of the specimens. The intersections were constructed of twelve ply + or - 45 sub 6 laminates of either Kevlar 49/934 or AS-4/934 graphite-epoxy in heights of 4, 8, and 12 inches. The geometry of the specimens varied in the designs of the intersection attachment angle. Four different geometries were tested.

  8. Chemical composition and photochemical reactivity of exhaust from aircraft turbine engines

    Directory of Open Access Journals (Sweden)

    T. F. Lyon

    Full Text Available Assessment of the environmental impact of aircraft emissions is required by planners and policy makers. Seveal areas of concern are: 1. exposure of airport workers and urban residents to toxic chemicals emitted when the engines operate at low power (idle and taxi on the ground; 2. contributions to urban photochemical air pollution of aircraft volatile organic and nitrogen oxides emissions from operations around airports; and 3. emissions of nitrogen oxides and particles during high-altitude operation. The environmental impact of chemicals emitted from jet aircraft turbine engines has not been firmly established due to lack of data regarding emission rates and identities of the compounds emitted. This paper describes an experimental study of two different aircraft turbine engines designed to determine detailed organic emissions, as well as emissions of inorganic gases. Emissions were measured at several engine power settings. Measurements were made of detailed organic composition from C1 through C17, CO, CO2, NO, NOx, and polycyclic aromatic hydrocarbons. Measurements were made using a multi-port sampling pro be positioned directly behind the engine in the exhaust exit plane. The emission measurements have been used to determine the organic distribution by carbon number and the distribution by compound class at each engine power level. The sum of the organic species was compared with an independent measurement of total organic carbon to assess the carbon mass balance. A portion of the exhaust was captured and irradiated in outdoor smog chambers to assess the photochemical reactivity of the emissions with respect to ozone formation. The reactivity of emissions from the two engines was apportioned by chemical compound class.

  9. Analysis and Testing of a Metallic Repair Applicable to Pressurized Composite Aircraft Structure

    Science.gov (United States)

    Przekop, Adam; Jegley, Dawn C.; Rouse, Marshall; Lovejoy, Andrew E.

    2014-01-01

    Development of repair technology is vital to the long-term application of new structural concepts on aircraft structure. The design, analysis, and testing of a repair concept applicable to a stiffened composite panel based on the Pultruded Rod Stitched Efficient Unitized Structure was recently completed. The damage scenario considered was a mid-bay to mid-bay saw-cut with a severed stiffener, flange, and skin. A bolted metallic repair was selected so that it could be easily applied in the operational environment. The present work describes results obtained from tension and pressure panel tests conducted to validate both the repair concept and finite element analysis techniques used in the design effort. Simulation and experimental strain and displacement results show good correlation, indicating that the finite element modeling techniques applied in the effort are an appropriate compromise between required fidelity and computational effort. Static tests under tension and pressure loadings proved that the proposed repair concept is capable of sustaining load levels that are higher than those resulting from the current working stress allowables. Furthermore, the pressure repair panel was subjected to 55,000 pressure load cycles to verify that the design can withstand a life cycle representative for a transport category aircraft. These findings enable upward revision of the stress allowables that had been kept at an overly-conservative level due to concerns associated with repairability of the panels. This conclusion enables more weight efficient structural designs utilizing the composite concept under investigation.

  10. An overview of the crash dynamics failure behavior of metal and composite aircraft structures

    Science.gov (United States)

    Carden, Huey D.; Boitnott, Richard L.; Fasanella, Edwin L.; Jones, Lisa E.

    1991-01-01

    An overview of failure behavior results is presented from some of the crash dynamics research conducted with concepts of aircraft elements and substructure not necessarily designed or optimized for energy absorption or crash loading considerations. Experimental and analytical data are presented that indicate some general trends in the failure behavior of a class of composite structures that includes fuselage panels, individual fuselage sections, fuselage frames, skeleton subfloors with stringers and floor beams without skin covering, and subfloors with skin added to the frame stringer structure. Although the behavior is complex, a strong similarity in the static/dynamic failure behavior among these structures is illustrated through photographs of the experimental results and through analytical data of generic composite structural models.

  11. Inter-laminar shear stress in hybrid CFRP/austenitic steel

    OpenAIRE

    Lopes, J.(Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil); Freitas, M; D. Stefaniak; Camanho, P.P.

    2015-01-01

    Bolted joints are the most common solution for joining composite components in aerospace structures. Critical structures such as wing to fuselage joints, or flight control surface fittings use bolted joining techniques. Recent research concluded that higher bearing strengths in composite bolted joints can be achieved by a CFRP/ Titanium hybrid lay-up in the vicinity of the bolted joint. The high costs of titanium motivate a similar research with the more cost competitive austeniti...

  12. A Study of the Utilization of Advanced Composites in Fuselage Structures of Commercial Aircraft

    Science.gov (United States)

    Watts, D. J.; Sumida, P. T.; Bunin, B. L.; Janicki, G. S.; Walker, J. V.; Fox, B. R.

    1985-01-01

    A study was conducted to define the technology and data needed to support the introduction of advanced composites in the future production of fuselage structure in large transport aircraft. Fuselage structures of six candidate airplanes were evaluated for the baseline component. The MD-100 was selected on the basis of its representation of 1990s fuselage structure, an available data base, its impact on the schedule and cost of the development program, and its availability and suitability for flight service evaluation. Acceptance criteria were defined, technology issues were identified, and a composite fuselage technology development plan, including full-scale tests, was identified. The plan was based on composite materials to be available in the mid to late 1980s. Program resources required to develop composite fuselage technology are estimated at a rough order of magnitude to be 877 man-years exclusive of the bird strike and impact dynamic test components. A conceptual composite fuselage was designed, retaining the basic MD-100 structural arrangement for doors, windows, wing, wheel wells, cockpit enclosure, major bulkheads, etc., resulting in a 32 percent weight savings.

  13. Analysis of the Dynamic Response in Blast-Loaded CFRP-Strengthened Metallic Beams

    Directory of Open Access Journals (Sweden)

    Zhenyu Wang

    2013-01-01

    Full Text Available Carbon fiber-reinforced polymer composites (CFRPs are good candidates in enhancing the blast resistant performance of vulnerable public buildings and in reinforcing old buildings. The use of CFRP in retrofitting and strengthening applications is traditionally associated with concrete structures. Nevertheless, more recently, there has been a remarkable aspiration in strengthening metallic structures and components using CFRP. This paper presents a relatively simple analytical solution for the deformation and ultimate strength calculation of hybrid metal-CFRP beams when subjected to pulse loading, with a particular focus on blast loading. The analytical model is based on a full interaction between the metal and the FRP and is capable of producing reasonable results in a dynamic loading scenario. A nonlinear finite element (FE model is also developed to reveal the full dynamic behavior of the CFRP-epoxy-steel hybrid beam, considering the detailed effects, that is, large strains, high strain rates in metal, and different failure modes of the hybrid beam. Experimental results confirm the analytical and the FE results and show a strong correlation.

  14. Rotary ultrasonic elliptical machining for side milling of CFRP: tool performance and surface integrity.

    Science.gov (United States)

    Geng, Daxi; Zhang, Deyuan; Xu, Yonggang; He, Fengtao; Liu, Dapeng; Duan, Zuoheng

    2015-05-01

    The rotary ultrasonic elliptical machining (RUEM) has been recognized as a new effective process to machining circular holes on CFRP materials. In CFRP face machining, the application of grinding tools is restricted for the tool clogging and the machined surface integrity. In this paper, we proposed a novel approach to extend the RUEM process to side milling of CFRP for the first time, which kept the effect of elliptical vibration in RUEM. The experiment apparatus was developed, and the preliminary experiments were designed and conducted, with comparison to conventional grinding (CG). The experimental results showed that when the elliptical vibration was applied in RUEM, a superior cutting process can be obtained compared with that in CG, including providing reduced cutting forces (2-43% decrement), an extended tool life (1.98 times), and improved surface integrity due to the intermittent material removal mechanism and the excellent chip removal conditions achieved in RUEM. It was concluded that the RUEM process is suitable to mill flat surface on CFRP composites.

  15. Flexural Strengthening of RC Slabs with Prestressed CFRP Strips Using Different Anchorage Systems

    Directory of Open Access Journals (Sweden)

    José Sena-Cruz

    2015-10-01

    Full Text Available Externally Bonded Reinforcement (EBR technique has been widely used for flexural strengthening of concrete structures by using carbon fiber-reinforced polymers (CFRP. EBR technique offers several structural advantages when the CFRP material is prestressed. This paper presents an experimental and numerical study on reinforced (RC slabs strengthened in flexure with prestressed CFRP strips as a structural strengthening system. The strips are applied as an externally bonded reinforcement (EBR and anchored with either a mechanical or a gradient anchorage. The former foresees metallic anchorage plates fixed to the concrete substrate, while the latter is based on an accelerated epoxy resin curing followed by a segment-wise prestress force decrease at the strip ends. Both anchorage systems, in combination with different CFRP strip geometries, were subjected to static loading tests. It could be demonstrated that the composite strip’s performance is better exploited when prestressing is used, with slightly higher overall load carrying capacities for mechanical anchorages than for the gradient anchorage. The performed investigations by means of a cross-section analysis supported the experimental observation that in case a mechanical anchorage is used, progressive strip debonding changes the fully bonded configuration to an unbonded end-anchored system. The inclusion of defined debonding criteria for both the anchorage zones and free length between the anchorage regions allowed to precisely capture the ultimate loading forces.

  16. CFRP Mechanical Anchorage for Externally Strengthened RC Beams under Flexure

    Science.gov (United States)

    Ali, Alnadher; Abdalla, Jamal; Hawileh, Rami; Galal, Khaled

    De-bonding of carbon fiber reinforced polymers (CFRP) sheets and plates from the concrete substrate is one of the major reasons behind premature failures of beams that are externally strengthened with such CFRP materials. To delay or prevent de-bonding and therefore enhancing the load carrying capacity of strengthened beams, several anchorage systems were developed and used. This paper investigates the use of CFRP mechanical anchorage of CFRP sheets and plates used to externally strengthen reinforced concrete beams under flexure. The pin-and-fan shape CFRP anchor, which is custom-made from typical rolled fiber sheets and bundles of loose fiber is used. Several reinforced concrete beams were casted and tested in standard four-point bending scheme to study the effectiveness of this anchorage system. The beams were externally strengthened in flexure with bonded CFRP sheets and plates and then fastened to the soffit of the beams' using various patterns of CFRP anchors. It is observed that the CFRP plates begins to separate from the beams as soon as de-bonding occurs in specimens without CFRP anchors, while in beams with CFRP anchors de-bonding was delayed leading to increase in the load carrying capacity over the un-anchored strengthened beams.

  17. Damage tolerance assessment of bonded composite doubler repairs for commercial aircraft applications

    Energy Technology Data Exchange (ETDEWEB)

    Roach, D.

    1998-08-01

    The Federal Aviation Administration has sponsored a project at its Airworthiness Assurance NDI Validation Center (AANC) to validate the use of bonded composite doublers on commercial aircraft. A specific application was chosen in order to provide a proof-of-concept driving force behind this test and analysis project. However, the data stemming from this study serves as a comprehensive evaluation of bonded composite doublers for general use. The associated documentation package provides guidance regarding the design, analysis, installation, damage tolerance, and nondestructive inspection of these doublers. This report describes a series of fatigue and strength tests which were conducted to study the damage tolerance of Boron-Epoxy composite doublers. Tension-tension fatigue and ultimate strength tests attempted to grow engineered flaws in coupons with composite doublers bonded to aluminum skin. An array of design parameters, including various flaw scenarios, the effects of surface impact, and other off-design conditions, were studied. The structural tests were used to: (1) assess the potential for interply delaminations and disbonds between the aluminum and the laminate, and (2) determine the load transfer and crack mitigation capabilities of composite doublers in the presence of severe defects. A series of specimens were subjected to ultimate tension tests in order to determine strength values and failure modes. It was demonstrated that even in the presence of extensive damage in the original structure (cracks, material loss) and in spite of non-optimum installations (adhesive disbonds), the composite doubler allowed the structure to survive more than 144,000 cycles of fatigue loading. Installation flaws in the composite laminate did not propagate over 216,000 fatigue cycles. Furthermore, the added impediments of impact--severe enough to deform the parent aluminum skin--and hot-wet exposure did not effect the doubler`s performance. Since the tests were conducting

  18. Evaluation of modal-based damage detection techniques for composite aircraft sandwich structures

    Science.gov (United States)

    Oliver, J. A.; Kosmatka, J. B.

    2005-05-01

    Composite sandwich structures are important as structural components in modern lightweight aircraft, but are susceptible to catastrophic failure without obvious forewarning. Internal damage, such as disbonding between skin and core, is detrimental to the structures' strength and integrity and thus must be detected before reaching critical levels. However, highly directional low density cores, such as Nomex honeycomb, make the task of damage detection and health monitoring difficult. One possible method for detecting damage in composite sandwich structures, which seems to have received very little research attention, is analysis of global modal parameters. This study will investigate the viability of modal analysis techniques for detecting skin-core disbonds in carbon fiber-Nomex honeycomb sandwich panels through laboratory testing. A series of carbon fiber prepreg and Nomex honeycomb sandwich panels-representative of structural components used in lightweight composite airframes-were fabricated by means of autoclave co-cure. All panels were of equal dimensions and two were made with predetermined sizes of disbonded areas, created by substituting areas of Teflon release film in place of epoxy film adhesive during the cure. A laser vibrometer was used to capture frequency response functions (FRF) of all panels, and then real and imaginary FRFs at different locations on each plate and operating shapes for each plate were compared. Preliminary results suggest that vibration-based techniques hold promise for damage detection of composite sandwich structures.

  19. Structural Analysis and Optimization of a Composite Fan Blade for Future Aircraft Engine

    Science.gov (United States)

    Coroneos, Rula M.

    2012-01-01

    This report addresses the structural analysis and optimization of a composite fan blade sized for a large aircraft engine. An existing baseline solid metallic fan blade was used as a starting point to develop a hybrid honeycomb sandwich construction with a polymer matrix composite face sheet and honeycomb aluminum core replacing the original baseline solid metallic fan model made of titanium. The focus of this work is to design the sandwich composite blade with the optimum number of plies for the face sheet that will withstand the combined pressure and centrifugal loads while the constraints are satisfied and the baseline aerodynamic and geometric parameters are maintained. To satisfy the requirements, a sandwich construction for the blade is proposed with composite face sheets and a weak core made of honeycomb aluminum material. For aerodynamic considerations, the thickness of the core is optimized whereas the overall blade thickness is held fixed so as to not alter the original airfoil geometry. Weight is taken as the objective function to be minimized by varying the core thickness of the blade within specified upper and lower bounds. Constraints are imposed on radial displacement limitations and ply failure strength. From the optimum design, the minimum number of plies, which will not fail, is back-calculated. The ply lay-up of the blade is adjusted from the calculated number of plies and final structural analysis is performed. Analyses were carried out by utilizing the OpenMDAO Framework, developed at NASA Glenn Research Center combining optimization with structural assessment.

  20. Structural Analysis and Optimization of a Composite Fan Blade for Future Aircraft Engine

    Science.gov (United States)

    Coroneos, Rula M.; Gorla, Rama Subba Reddy

    2012-09-01

    This paper addresses the structural analysis and optimization of a composite sandwich ply lay-up of a NASA baseline solid metallic fan blade comparable to a future Boeing 737 MAX aircraft engine. Sandwich construction with a polymer matrix composite face sheet and honeycomb aluminum core replaces the original baseline solid metallic fan model made of Titanium. The focus of this work is to design the sandwich composite blade with the optimum number of plies for the face sheet that will withstand the combined pressure and centrifugal loads while the constraints are satisfied and the baseline aerodynamic and geometric parameters are maintained. To satisfy the requirements a sandwich construction for the blade is proposed with composite face sheets and a weak core made of honeycomb aluminum material. For aerodynamic considerations, the thickness of the core is optimized where as the overall blade thickness is held fixed in order not to alter the original airfoil geometry. Weight reduction is taken as the objective function by varying the core thickness of the blade within specified upper and lower bounds. Constraints are imposed on radial displacement limitations and ply failure strength. From the optimum design, the minimum number of plies, which will not fail, is back-calculated. The ply lay-up of the blade is adjusted from the calculated number of plies and final structural analysis is performed. Analyses were carried out by utilizing the OpenMDAO Framework, developed at NASA Glenn Research Center combining optimization with structural assessment.

  1. Influence of Implementation of Composite Materials in Civil Aircraft Industry on reduction of Environmental Pollution and Greenhouse Effect

    International Nuclear Information System (INIS)

    Computer-based Life Cycle Analysis (LCA) models were carried out to compare lightweight composites with the traditional aluminium over their useful lifetime. The analysis included raw materials, production, useful life in operation and disposal at the end of the material's useful life. The carbon fibre epoxy resin composite could in some cases reduce the weight of a component by up to 40 % compared to aluminium. As the fuel consumption of an aircraft is strongly influenced by its total weight, the emissions can be significantly reduced by increasing the proportion of composites used in the aircraft structure. Higher emissions, compared to aluminium, produced during composites production meet their 'break even' point after certain number of time units when used in aircraft structures, and continue to save emissions over their long-term operation. The study highlighted the environmental benefits of using lightweight structures in aircraft design, and also showed that utilisation of composites in products without energy saving may lead to increased emissions in the environment.

  2. Weight Assessment for Fuselage Shielding on Aircraft With Open-Rotor Engines and Composite Blade Loss

    Science.gov (United States)

    Carney, Kelly; Pereira, Michael; Kohlman, Lee; Goldberg, Robert; Envia, Edmane; Lawrence, Charles; Roberts, Gary; Emmerling, William

    2013-01-01

    The Federal Aviation Administration (FAA) has been engaged in discussions with airframe and engine manufacturers concerning regulations that would apply to new technology fuel efficient "openrotor" engines. Existing regulations for the engines and airframe did not envision features of these engines that include eliminating the fan blade containment systems and including two rows of counter-rotating blades. Damage to the airframe from a failed blade could potentially be catastrophic. Therefore the feasibility of using aircraft fuselage shielding was investigated. In order to establish the feasibility of this shielding, a study was conducted to provide an estimate for the fuselage shielding weight required to provide protection from an open-rotor blade loss. This estimate was generated using a two-step procedure. First, a trajectory analysis was performed to determine the blade orientation and velocity at the point of impact with the fuselage. The trajectory analysis also showed that a blade dispersion angle of 3deg bounded the probable dispersion pattern and so was used for the weight estimate. Next, a finite element impact analysis was performed to determine the required shielding thickness to prevent fuselage penetration. The impact analysis was conducted using an FAA-provided composite blade geometry. The fuselage geometry was based on a medium-sized passenger composite airframe. In the analysis, both the blade and fuselage were assumed to be constructed from a T700S/PR520 triaxially-braided composite architecture. Sufficient test data on T700S/PR520 is available to enable reliable analysis, and also demonstrate its good impact resistance properties. This system was also used in modeling the surrogate blade. The estimated additional weight required for fuselage shielding for a wing- mounted counterrotating open-rotor blade is 236 lb per aircraft. This estimate is based on the shielding material serving the dual use of shielding and fuselage structure. If the

  3. Flight service evaluation of Kevlar-49 epoxy composite panels in wide-bodied commercial transport aircraft

    Science.gov (United States)

    Stone, R. H.

    1984-01-01

    Kevlar-49 fairing panels, installed as flight service components on three L-1011s, were inspected after 10 years of service. There are six Kevlar-49 panels on each aircraft: a left-hand and right-hand set of a wing-body sandwich fairing; a solid laminate under-wing fillet panel; and a 422 K (300 F) service aft engine fairing. The three L-1011s include one each in service with Eastern, Air Canada, and TWA. The fairings have accumulated a total of 79,568 hours, with one ship set having nearly 28,000 hours service. The inspections were conducted at the airlines' major maintenance bases with the participation of Lockheed Engineering. The Kevlar-49 components were found to be performing satisfactorily in service with no major problems, or any condition requiring corrective action. The only defects noted were minor impact damage, a few minor disbonds and a minor degree of fastener hole fraying and elongation. These are for the most part comparable to damage noted on fiberglass fairings. The service history obtained in this program indicates that Kevlar-49 epoxy composite materials have satisfactory service characteristics for use in aircraft secondary structure.

  4. Testing and Analysis of a Composite Non-Cylindrical Aircraft Fuselage Structure . Part II; Severe Damage

    Science.gov (United States)

    Przekop, Adam; Jegley, Dawn C.; Lovejoy, Andrew E.; Rouse, Marshall; Wu, Hsi-Yung T.

    2016-01-01

    The Environmentally Responsible Aviation Project aimed to develop aircraft technologies enabling significant fuel burn and community noise reductions. Small incremental changes to the conventional metallic alloy-based 'tube and wing' configuration were not sufficient to achieve the desired metrics. One airframe concept identified by the project as having the potential to dramatically improve aircraft performance was a composite-based hybrid wing body configuration. Such a concept, however, presented inherent challenges stemming from, among other factors, the necessity to transfer wing loads through the entire center fuselage section which accommodates a pressurized cabin confined by flat or nearly flat panels. This paper discusses a finite element analysis and the testing of a large-scale hybrid wing body center section structure developed and constructed to demonstrate that the Pultruded Rod Stitched Efficient Unitized Structure concept can meet these challenging demands of the next generation airframes. Part II of the paper considers the final test to failure of the test article in the presence of an intentionally inflicted severe discrete source damage under the wing up-bending loading condition. Finite element analysis results are compared with measurements acquired during the test and demonstrate that the hybrid wing body test article was able to redistribute and support the required design loads in a severely damaged condition.

  5. Behavior of preloaded RC beams strengthened with CFRP laminates

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Eighteen reinforced concrete beams, including 16 beams strengthened with CFRP laminate at different levels of preload and 2 control beams, were tested to investigate the influence ofpreload level on flexural behavior of CFRP-strengthened RC beam. The experimental parameters include rebar ratios, number of plies of CFRP laminates and preload level at the time of strengthening. Theoretical analysis was also carried out to explain the experimental phenomena and results. The experimental and theoretical results indicated that the preload level has more influence on the stiffness and deflection of the strengthened beam, bothat post-cracking and post-yielding stage, than that on the yielding and ultimate flexural strength of the strengthened beam. The main failure mode of CFRP-strengthened beam is the intermediate crack-induced debonding of CFRP laminates, provided that the development length of CFRP laminates and shear capacity of the beam are sufficient.

  6. Structural Design Optimization of a Tiltrotor Aircraft Composite Wing to Enhance Whirl Flutter Stability

    DEFF Research Database (Denmark)

    Kim, Taeseong; Kim, Jaehoon; Shin, Sang Joon;

    2013-01-01

    In order to enhance the aeroelastic stability of a tiltrotor aircraft, a structural optimization framework is developed by applying a multi-level optimization approach. Each optimization level is designed to achieve a different purpose; therefore, relevant optimization schemes are selected for each...... level. Enhancement of the aeroelastic stability is selected as an objective in the upper-level optimization. This is achieved by seeking the optimal structural properties of a composite wing, including its mass, vertical, chordwise, and torsional stiffness. In the upper-level optimization, the response...... surface method (RSM), is selected. On the other hand, lower-level optimization seeks to determine the local detailed cross-sectional parameters, such as the ply orientation angles and ply thickness, which are relevant to the wing structural properties obtained at the upper-level. To avoid manufacturing...

  7. Assessment of the State-of-the-Art in the Design and Manufacturing of Large Composite Structure

    Science.gov (United States)

    Harris, C. E.

    2001-01-01

    This viewgraph presentation gives an assessment of the state-of-the-art in the design and manufacturing of large component structures, including details on the use of continuous fiber reinforced polymer matrix composites (CFRP) in commercial and military aircraft and in space launch vehicles. Project risk mitigation plans must include a building-block test approach to structural design development, manufacturing process scale-up development tests, and pre-flight ground tests to verify structural integrity. The potential benefits of composite structures justifies NASA's investment in developing the technology. Advanced composite structures technology is enabling to virtually every Aero-Space Technology Enterprise Goal.

  8. Study of the Tensile Properties of CFRP Strengthened Steel Plates

    OpenAIRE

    Yiyan Lu; Weijie Li; Shan Li; Xiaojin Li; Tao Zhu

    2015-01-01

    This paper presents the experimental results of steel plates strengthened with carbon fiber reinforced polymer (CFRP) sheets under tensile load. The number of CFRP layers (ranging from one to four), strengthening schemes (single-sided and double-sided bonding), and temperatures (ranging from 25 to 120 °C) were investigated. Results showed that the number of CFRP layers and strengthening schemes had insignificant effects on failure modes of specimens. The failure modes were dominated by the de...

  9. Decontamination of radioactive P[sup 32] and I[sup 131] from aircraft and car surfaces by detergent compositions

    Energy Technology Data Exchange (ETDEWEB)

    Soliman, H.M. (King Abdulazis Military Academy, Dept. of Chemistry, Riyadh (Saudi Arabia)); Badawi, A.M. (Petroleum Research Inst., Dept. of Application, Cairo (Egypt)); Mokhtar, W.M.

    Sheets from aircrafts and cars having the same surfaces were contaminated with solutions of radioactive phosphorus salts and solutions of radioactive iodine salts. Different compositions from synthetic detergents and locally available complexing salts were prepared and their efficiencies in decontaminating the sheets were measured under the same conditions. The most effective compositions were those in which 'Berol Lanco' and 'Nestabon' were used. (orig.)

  10. Optimal design of a composite wing structure for a flying-wing aircraft subject to multi-constraint

    OpenAIRE

    Xu, Rongxin

    2012-01-01

    This thesis presents a research project and results of design and optimization of a composite wing structure for a large aircraft in flying wing configuration. The design process started from conceptual design and preliminary design, which includes initial sizing and stressing followed by numerical modelling and analysis of the wing structure. The research was then focused on the minimum weight optimization of the /composite wing structure /subject to multiple design /constraints. The modelli...

  11. Evaluation of Seismic Behaviors of Partially Deteriorated Reinforced Concrete Circular Columns Retrofitted with CFRP

    OpenAIRE

    Dongxu Hou; Jianyun Pan; Xinglang Fan; Zhimin Wu; Prosper Marindiko

    2014-01-01

    Deficiency of the concrete strength in some regions of reinforced concrete (RC) columns in practice may weaken the seismic behaviors of columns. Its effects on RC columns should be well understood. This paper aims to investigate the influences of deteriorated segment on the seismic behaviors of partially deteriorated RC columns and attempts to recover the seismic behaviors of partially deteriorated columns with Carbon Fiber Reinforced Polymer (CFRP) composites. A finite element analysis was c...

  12. A KBE-enabled design framework for cost/weight optimization study of aircraft composite structures

    Science.gov (United States)

    Wang, H.; La Rocca, G.; van Tooren, M. J. L.

    2014-10-01

    Traditionally, minimum weight is the objective when optimizing airframe structures. This optimization, however, does not consider the manufacturing cost which actually determines the profit of the airframe manufacturer. To this purpose, a design framework has been developed able to perform cost/weight multi-objective optimization of an aircraft component, including large topology variations of the structural configuration. The key element of the proposed framework is a dedicated knowledge based engineering (KBE) application, called multi-model generator, which enables modelling very different product configurations and variants and extract all data required to feed the weight and cost estimation modules, in a fully automated fashion. The weight estimation method developed in this research work uses Finite Element Analysis to calculate the internal stresses of the structural elements and an analytical composite plate sizing method to determine their minimum required thicknesses. The manufacturing cost estimation module was developed on the basis of a cost model available in literature. The capability of the framework was successfully demonstrated by designing and optimizing the composite structure of a business jet rudder. The study case indicates the design framework is able to find the Pareto optimal set for minimum structural weight and manufacturing costin a very quick way. Based on the Pareto set, the rudder manufacturer is in conditions to conduct both internal trade-off studies between minimum weight and minimum cost solutions, as well as to offer the OEM a full set of optimized options to choose, rather than one feasible design.

  13. The effect of material heterogeneity in curved composite beams for use in aircraft structures

    Science.gov (United States)

    Otoole, Brendan J.; Santare, Michael H.

    1992-01-01

    A design tool is presented for predicting the effect of material heterogeneity on the performance of curved composite beams for use in aircraft fuselage structures. Material heterogeneity can be induced during processes such as sheet forming and stretch forming of thermoplastic composites. This heterogeneity can be introduced in the form of fiber realignment and spreading during the manufacturing process causing a gradient in material properties in both the radial and tangential directions. The analysis procedure uses a separate two-dimensional elasticity solution for the stresses in the flanges and web sections of the beam. The separate solutions are coupled by requiring the forces and displacements match at the section boundaries. Analysis is performed for curved beams loaded in pure bending and uniform pressure. The beams can be of any general cross-section such as a hat, T-, I-, or J-beam. Preliminary results show that geometry of the beam dictates the effect of heterogeneity on performance. Heterogeneity plays a much larger role in beams with a small average radius to depth ratio, R/t, where R is the average radius of the beam and t is the difference between the inside and outside radius. Results of the analysis are in the form of stresses and displacements, and they are compared to both mechanics of materials and numerical solutions obtained using finite element analysis.

  14. The stable isotopic composition of molecular hydrogen in the tropopause region probed by the CARIBIC aircraft

    Science.gov (United States)

    Batenburg, A. M.; Schuck, T. J.; Baker, A. K.; Zahn, A.; Brenninkmeijer, C. A. M.; Röckmann, T.

    2012-05-01

    More than 450 air samples that were collected in the upper troposphere - lower stratosphere (UTLS) region by the CARIBIC aircraft (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) have been analyzed for molecular hydrogen (H2) mixing ratios (χ(H2)) and H2 isotopic composition (deuterium content, δD). More than 120 of the analyzed samples contained air from the lowermost stratosphere (LMS). These show that χ(H2) does not vary appreciably with O3-derived height above the thermal tropopause (TP), whereas δD does increase with height. The isotope enrichment is caused by H2 production and destruction processes that enrich the stratospheric H2 reservoir in deuterium (D); the exact shapes of the profiles are mainly determined by mixing of stratospheric with tropospheric air. Tight negative correlations are found between δD and the mixing ratios of methane (χ(CH4)) and nitrous oxide (χ(N2O)), as a result of the relatively long lifetimes of these three species. The correlations are described by δD[‰]=-0.35 · χ(CH4)[ppb]+768 and δD[‰]=-1.90· χ(N2O)[ppb]+745. These correlations are similar to previously published results and likely hold globally for the LMS. Samples that were collected from the Indian subcontinent up to 40° N before, during and after the summer monsoon season show no significant seasonal change in χ(H2), but δD is up to 12.3‰ lower in the July, August and September monsoon samples. This δD decrease is correlated with the χ(CH4) increase in these samples. The significant correlation with χ(CH4) and the absence of a perceptible χ(H2) increase that accompanies the δD decrease indicates that microbial production of very D-depleted H2 in the wet season may contribute to this phenomenon. Some of the samples have very high χ(H2) and very low δD values, which indicates a pollution effect. Aircraft engine exhaust plumes are a suspected cause, since the effect mostly occurs in samples

  15. Nonlinear Finite Element Analysis of a Composite Non-Cylindrical Pressurized Aircraft Fuselage Structure

    Science.gov (United States)

    Przekop, Adam; Wu, Hsi-Yung T.; Shaw, Peter

    2014-01-01

    The Environmentally Responsible Aviation Project aims to develop aircraft technologies enabling significant fuel burn and community noise reductions. Small incremental changes to the conventional metallic alloy-based 'tube and wing' configuration are not sufficient to achieve the desired metrics. One of the airframe concepts that might dramatically improve aircraft performance is a composite-based hybrid wing body configuration. Such a concept, however, presents inherent challenges stemming from, among other factors, the necessity to transfer wing loads through the entire center fuselage section which accommodates a pressurized cabin confined by flat or nearly flat panels. This paper discusses a nonlinear finite element analysis of a large-scale test article being developed to demonstrate that the Pultruded Rod Stitched Efficient Unitized Structure concept can meet these challenging demands of the next generation airframes. There are specific reasons why geometrically nonlinear analysis may be warranted for the hybrid wing body flat panel structure. In general, for sufficiently high internal pressure and/or mechanical loading, energy related to the in-plane strain may become significant relative to the bending strain energy, particularly in thin-walled areas such as the minimum gage skin extensively used in the structure under analysis. To account for this effect, a geometrically nonlinear strain-displacement relationship is needed to properly couple large out-of-plane and in-plane deformations. Depending on the loading, this nonlinear coupling mechanism manifests itself in a distinct manner in compression- and tension-dominated sections of the structure. Under significant compression, nonlinear analysis is needed to accurately predict loss of stability and postbuckled deformation. Under significant tension, the nonlinear effects account for suppression of the out-of-plane deformation due to in-plane stretching. By comparing the present results with the previously

  16. Insights into Submicron Aerosol Composition and Sources from the WINTER Aircraft Campaign Over the Eastern US.

    Science.gov (United States)

    Schroder, J. C.; Campuzano Jost, P.; Day, D. A.; Fibiger, D. L.; McDuffie, E. E.; Blake, N. J.; Hills, A. J.; Hornbrook, R. S.; Apel, E. C.; Weinheimer, A. J.; Campos, T. L.; Brown, S. S.; Jimenez, J. L.

    2015-12-01

    The WINTER aircraft campaign was a recent field experiment to probe the sources and evolution of gas pollutants and aerosols in Northeast US urban and industrial plumes during the winter. A highly customized Aerodyne aerosol mass spectrometer (AMS) was flown on the NCAR C-130 to characterize submicron aerosol composition and evolution. Thirteen research flights were conducted covering a wide range of conditions, including rural, urban, and marine environments during day and night. Organic aerosol (OA) was a large component of the submicron aerosol in the boundary layer. The fraction of OA (fOA) was smaller (35-40%) than in recent US summer campaigns (~60-70%). Biomass burning was observed to be an important source of OA in the boundary layer, which is consistent with recent wintertime studies that show a substantial contribution of residential wood burning to the OA loadings. OA oxygenation (O/C ratio) shows a broad distribution with a substantial fraction of smaller O/C ratios when compared to previous summertime campaigns. Since measurements were rarely made very close to primary sources (i.e. directly above urban areas), this is consistent with oxidative chemistry being slower during winter. SOA formation and aging in the NYC plume was observed during several flights and compared with summertime results from LA (CalNex) and Mexico City (MILAGRO). Additionally, an oxidation flow reactor (OFR) capable of oxidizing ambient air up to several equivalent days of oxidation was deployed for the first time in an aircraft platform. The aerosol outflow of the OFR was sampled with the AMS to provide real-time snapshots of the potential for aerosol formation and aging. For example, a case study of a flight through the Ohio River valley showed evidence of oxidation of SO2 to sulfate. The measured sulfate enhancements were in good agreement with our OFR chemical model. OFR results for SOA will be discussed.

  17. Strengthening of a railway bridge with NSMR and CFRP tubes

    DEFF Research Database (Denmark)

    Täljsten, Björn; Bennitz, Anders; Danielsson, Georg

    2008-01-01

    Strengthening of structures with CFRP is today considered an accepted method to upgrade concrete structures. In this paper two different CFRP strengthening systems are combined to give extended service life to a Swedish double-trough-double-track railway bridge, constructed in concrete with a 10...

  18. Finite element analysis of hypervelocity impact behaviour of CFRP-Al/HC sandwich panel

    Directory of Open Access Journals (Sweden)

    Phadnis Vaibhav A.

    2015-01-01

    Full Text Available The mechanical response of CFRP-Al/HC (carbon fibre-reinforced/epoxy composite face sheets with Al honeycomb core sandwich panels to hyper-velocity impact (up to 1 km/s is studied using a finite-element model developed in ABAQUS/Explicit. The intraply damage of CFRP face sheets is analysed by mean of a user-defined material model (VUMAT employing a combination of Hashin and Puck criteria, delamination modelled using cohesive-zone elements. The damaged Al/HC core is assessed on the basis of a Johnson Cook dynamic failure model while its hydrodynamic response is captured using the Mie-Gruneisen equation of state. The results obtained with the developed finite-element model showed a reasonable correlation to experimental damage patterns. The surface peeling of both face sheets was evident, with a significant delamination around the impact location accompanied by crushing HC core.

  19. CFRP mirror technology for cryogenic space interferometry: review and progress to date

    Science.gov (United States)

    Jones, Martyn L.; Walker, David; Naylor, David A.; Veenendaal, Ian T.; Gom, Brad G.

    2016-07-01

    The FP7 project, FISICA (Far Infrared Space Interferometer Critical Assessment), called for the investigation into the suitability of Carbon fiber Reinforced Plastic (CFRP) for a 2m primary mirror. In this paper, we focus on the major challenge for application, the development of a mirror design that would maintain its form at cryogenic temperatures. In order to limit self-emission the primary is to be cooled to 4K whilst not exceeding a form error of 275nm PV. We then describe the development of an FEA model that utilizes test data obtained from a cryogenic test undertaken at the University of Lethbridge on CFRP samples. To conclude, suggestions are made in order to advance this technology to be suitable for such an application in order to exploit the low density and superior specific properties of polymeric composites.

  20. Study on Evaluating Damage of CFRP Using the PVDF Comb Transducer

    International Nuclear Information System (INIS)

    Recently, fiber reinforced plastic (FRP) materials become to be used more in producing airplanes because of high specific strength and low weight. However, there can be delamination caused from unexpected impact during the service flight. Since strength reduce comes with these delamination defects, defects in the composite materials should be monitored for safety of the airplane. A PVDF transducer can be used for on-line health monitoring economically. In this study, comb type of PVDF transducer was fabricated for generating and receiving of the guided wave at specific wavelength and was applied to evaluate natural delamination defect with the guided wave. Natural delamination in CFRP was produced with free dropping weight on CFRP surface between the transmitter and the receiver transducers. At every impacts, guided wave was generated and received in the pitch-catch way with the PVDF(Polyvinylidene fluoride) comb transducer and variation of the guided wave signal was compared according to accumulation of impact damage.

  1. Multifunctional Hybrid Carbon Nanotube/Carbon Fiber Polymer Composites

    Science.gov (United States)

    Kang, Jin Ho; Cano, Roberto J.; Ratcliffe, James G.; Luong, Hoa; Grimsley, Brian W.; Siochi, Emilie J.

    2016-01-01

    For aircraft primary structures, carbon fiber reinforced polymer (CFRP) composites possess many advantages over conventional aluminum alloys due to their light weight, higher strengthand stiffness-to-weight ratio, and low life-cycle maintenance costs. However, the relatively low electrical and thermal conductivities of CFRP composites fail to provide structural safety in certain operational conditions such as lightning strikes. Despite several attempts to solve these issues with the addition of carbon nanotubes (CNT) into polymer matrices, and/or by interleaving CNT sheets between conventional carbon fiber (CF) composite layers, there are still interfacial problems that exist between CNTs (or CF) and the resin. In this study, hybrid CNT/CF polymer composites were fabricated by interleaving layers of CNT sheets with Hexcel® IM7/8852 prepreg. Resin concentrations from 1 wt% to 50 wt% were used to infuse the CNT sheets prior to composite fabrication. The interlaminar properties of the resulting hybrid composites were characterized by mode I and II fracture toughness testing (double cantilever beam and end-notched flexure test). Fractographical analysis was performed to study the effect of resin concentration. In addition, multi-directional physical properties like thermal conductivity of the orthotropic hybrid polymer composite were evaluated. Interleaving CNT sheets significantly improved the in-plane (axial and perpendicular direction of CF alignment) thermal conductivity of the hybrid composite laminates by 50 - 400%.

  2. Shear capacity of reinforced concrete columns strengthened with CFRP sheet

    Institute of Scientific and Technical Information of China (English)

    XIE Jian; LIU Xue-mei; ZHAO Tong

    2005-01-01

    This paper discusses the results of tests on the shear capacity of reinforced concrete columns strengthened with carbon fiber reinforced plastic (CFRP) sheet. The shear transfer mechanism of the specimens reinforced with CFRP sheet was studied. The factors affecting the shear capacity of reinforced concrete columns strengthened with CFRP sheet were analyzed. Several suggestions such as the number of layers, width and tensile strength of the CFRP sheet are proposed for this new strengthening technique. Finally, a simple and practical design method is presented in the paper. The calculated results of the suggested method are shown to be in good agreement with the test results. The suggested design method can be used in evaluating the shear capacity of reinforced concrete columns strengthened with CFRP sheet.

  3. Full-scale testing and progressive damage modeling of sandwich composite aircraft fuselage structure

    Science.gov (United States)

    Leone, Frank A., Jr.

    A comprehensive experimental and computational investigation was conducted to characterize the fracture behavior and structural response of large sandwich composite aircraft fuselage panels containing artificial damage in the form of holes and notches. Full-scale tests were conducted where panels were subjected to quasi-static combined pressure, hoop, and axial loading up to failure. The panels were constructed using plain-weave carbon/epoxy prepreg face sheets and a Nomex honeycomb core. Panel deformation and notch tip damage development were monitored during the tests using several techniques, including optical observations, strain gages, digital image correlation (DIC), acoustic emission (AE), and frequency response (FR). Additional pretest and posttest inspections were performed via thermography, computer-aided tap tests, ultrasound, x-radiography, and scanning electron microscopy. The framework to simulate damage progression and to predict residual strength through use of the finite element (FE) method was developed. The DIC provided local and full-field strain fields corresponding to changes in the state-of-damage and identified the strain components driving damage progression. AE was monitored during loading of all panels and data analysis methodologies were developed to enable real-time determination of damage initiation, progression, and severity in large composite structures. The FR technique has been developed, evaluating its potential as a real-time nondestructive inspection technique applicable to large composite structures. Due to the large disparity in scale between the fuselage panels and the artificial damage, a global/local analysis was performed. The global FE models fully represented the specific geometries, composite lay-ups, and loading mechanisms of the full-scale tests. A progressive damage model was implemented in the local FE models, allowing the gradual failure of elements in the vicinity of the artificial damage. A set of modifications

  4. Mechanical Properties of Composite Materials

    Directory of Open Access Journals (Sweden)

    Mitsuhiro Okayasu

    2014-10-01

    Full Text Available An examination has been made of the mechanical and failure properties of several composite materials, such as a short and a long carbon fiber reinforced plastic (short- and long-CFRP and metal based composite material. The short CFRP materials were used for a recycled CFRP which fabricated by the following process: the CFRP, consisting of epoxy resin with carbon fiber, is injected to a rectangular plate cavity after mixing with acrylonitrile butadiene styrene resin with different weight fractions of CFRP. The fatigue and ultimate tensile strength (UTS increased with increasing CFRP content. These correlations, however, break down, especially for tensile strength, as the CFPR content becomes more than 70%. Influence of sample temperature on the bending strength of the long-CFRP was investigated, and it appears that the strength slightly decreases with increasing the temperature, due to the weakness in the matrix. Broken fiber and pull-out or debonding between the fiber and matrix were related to the main failure of the short- and long-CFRP samples. Mechanical properties of metal based composite materials have been also investigated, where fiber-like high hardness CuAl2 structure is formed in aluminum matrix. Excellent mechanical properties were obtained in this alloy, e.g., the higher strength and the higher ductility, compared tothe same alloy without the fiber-like structure. There are strong anisotropic effects on the mechanical properties due to the fiber-like metal composite in a soft Al based matrix.

  5. Mechanical testing and modelling of carbon-carbon composites for aircraft disc brakes

    Science.gov (United States)

    Bradley, Luke R.

    The objective of this study is to improve the understanding of the stress distributions and failure mechanisms experienced by carbon-carbon composite aircraft brake discs using finite element (FE) analyses. The project has been carried out in association with Dunlop Aerospace as an EPSRC CASE studentship. It therefore focuses on the carbon-carbon composite brake disc material produced by Dunlop Aerospace, although it is envisaged that the approach will have broader applications for modelling and mechanical testing of carbon-carbon composites in general. The disc brake material is a laminated carbon-carbon composite comprised of poly(acrylonitrile) (PAN) derived carbon fibres in a chemical vapour infiltration (CVI) deposited matrix, in which the reinforcement is present in both continuous fibre and chopped fibre forms. To pave the way for the finite element analysis, a comprehensive study of the mechanical properties of the carbon-carbon composite material was carried out. This focused largely, but not entirely, on model composite materials formulated using structural elements of the disc brake material. The strengths and moduli of these materials were measured in tension, compression and shear in several orientations. It was found that the stress-strain behaviour of the materials were linear in directions where there was some continuous fibre reinforcement, but non-linear when this was not the case. In all orientations, some degree of non-linearity was observed in the shear stress-strain response of the materials. However, this non-linearity was generally not large enough to pose a problem for the estimation of elastic moduli. Evidence was found for negative Poisson's ratio behaviour in some orientations of the material in tension. Additionally, the through-thickness properties of the composite, including interlaminar shear strength, were shown to be positively related to bulk density. The in-plane properties were mostly unrelated to bulk density over the range of

  6. Preliminary study on rotary ultrasonic machining of CFRP/Ti stacks.

    Science.gov (United States)

    Cong, W L; Pei, Z J; Treadwell, C

    2014-08-01

    Reported drilling methods for CFRP/Ti stacks include twist drilling, end milling, core grinding, and their derived methods. The literature does not have any report on drilling of CFRP/Ti stacks using rotary ultrasonic machining (RUM). This paper, for the first time, reports a study on drilling of CFRP/Ti stacks using RUM. It also compares results on drilling of CFRP/Ti stacks using RUM with reported results on drilling of CFRP/Ti stacks using other methods. When drilling CFRP/Ti stacks using RUM, cutting force, torque, and CFRP surface roughness were lower, hole size variation was smaller, CFRP groove depth was smaller, tool life was longer, and there was no obvious Ti exit burr and CFRP entrance delamination. Ti surface roughness when drilling of CFRP/Ti stacks using RUM was about the same as those when using other methods.

  7. Impact imaging of aircraft composite structure based on a model-independent spatial-wavenumber filter.

    Science.gov (United States)

    Qiu, Lei; Liu, Bin; Yuan, Shenfang; Su, Zhongqing

    2016-01-01

    The spatial-wavenumber filtering technique is an effective approach to distinguish the propagating direction and wave mode of Lamb wave in spatial-wavenumber domain. Therefore, it has been gradually studied for damage evaluation in recent years. But for on-line impact monitoring in practical application, the main problem is how to realize the spatial-wavenumber filtering of impact signal when the wavenumber of high spatial resolution cannot be measured or the accurate wavenumber curve cannot be modeled. In this paper, a new model-independent spatial-wavenumber filter based impact imaging method is proposed. In this method, a 2D cross-shaped array constructed by two linear piezoelectric (PZT) sensor arrays is used to acquire impact signal on-line. The continuous complex Shannon wavelet transform is adopted to extract the frequency narrowband signals from the frequency wideband impact response signals of the PZT sensors. A model-independent spatial-wavenumber filter is designed based on the spatial-wavenumber filtering technique. Based on the designed filter, a wavenumber searching and best match mechanism is proposed to implement the spatial-wavenumber filtering of the frequency narrowband signals without modeling, which can be used to obtain a wavenumber-time image of the impact relative to a linear PZT sensor array. By using the two wavenumber-time images of the 2D cross-shaped array, the impact direction can be estimated without blind angle. The impact distance relative to the 2D cross-shaped array can be calculated by using the difference of time-of-flight between the frequency narrowband signals of two different central frequencies and the corresponding group velocities. The validations performed on a carbon fiber composite laminate plate and an aircraft composite oil tank show a good impact localization accuracy of the model-independent spatial-wavenumber filter based impact imaging method.

  8. The stable isotopic composition of molecular hydrogen in the tropopause region probed by the CARIBIC aircraft

    Directory of Open Access Journals (Sweden)

    A. M. Batenburg

    2012-05-01

    Full Text Available More than 450 air samples that were collected in the upper troposphere – lower stratosphere (UTLS region by the CARIBIC aircraft (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container have been analyzed for molecular hydrogen (H2 mixing ratios (χ(H2 and H2 isotopic composition (deuterium content, δD.

    More than 120 of the analyzed samples contained air from the lowermost stratosphere (LMS. These show that χ(H2 does not vary appreciably with O3-derived height above the thermal tropopause (TP, whereas δD does increase with height. The isotope enrichment is caused by H2 production and destruction processes that enrich the stratospheric H2 reservoir in deuterium (D; the exact shapes of the profiles are mainly determined by mixing of stratospheric with tropospheric air. Tight negative correlations are found between δD and the mixing ratios of methane (χ(CH4 and nitrous oxide (χ(N2O, as a result of the relatively long lifetimes of these three species. The correlations are described by δD[‰]=−0.35 · χ(CH4[ppb]+768 and δD[‰]=−1.90· χ(N2O[ppb]+745. These correlations are similar to previously published results and likely hold globally for the LMS.

    Samples that were collected from the Indian subcontinent up to 40° N before, during and after the summer monsoon season show no significant seasonal change in χ(H2, but δD is up to 12.3‰ lower in the July, August and September monsoon samples. This δD decrease is correlated with the χ(CH4 increase in these samples. The significant correlation with χ(CH4 and the absence of a perceptible χ(H2 increase that accompanies the δD decrease indicates that microbial production of

  9. An assessment of tailoring of lightning protection design requirements for a composite wing structure on a metallic aircraft

    Science.gov (United States)

    Harwood, T. L.

    1991-01-01

    The Navy A-6E aircraft is presently being modified with a new wing which uses graphite/epoxy structures and substructures around a titanium load-bearing structure. The ability of composites to conduct electricity is less than that of aluminum. This is cause for concern when the wing may be required to conduct large lightning currents. The manufacturer attempted to solve lightning protection issues by performing a risk assessment based on a statistical approach which allows relaxation of the wing lightning protection design levels over certain locations of the composite wing. A sensitivity study is presented designed to define the total risk of relaxation of the design levels.

  10. Strengthening of defected beam–column joints using CFRP

    Directory of Open Access Journals (Sweden)

    Mohamed H. Mahmoud

    2014-01-01

    Full Text Available This paper presents an experimental study for the structural performance of reinforced concrete (RC exterior beam–column joints rehabilitated using carbon-fiber-reinforced polymer (CFRP. The present experimental program consists of testing 10 half-scale specimens divided into three groups covering three possible defects in addition to an adequately detailed control specimen. The considered defects include the absence of the transverse reinforcement within the joint core, insufficient bond length for the beam main reinforcement and inadequate spliced implanted column on the joint. Three different strengthening schemes were used to rehabilitate the defected beam–column joints including externally bonded CFRP strips and sheets in addition to near surface mounted (NSM CFRP strips. The failure criteria including ultimate capacity, mode of failure, initial stiffness, ductility and the developed ultimate strain in the reinforcing steel and CFRP were considered and compared for each group for the control and the CFRP-strengthened specimens. The test results showed that the proposed CFRP strengthening configurations represented the best choice for strengthening the first two defects from the viewpoint of the studied failure criteria. On the other hand, the results of the third group showed that strengthening the joint using NSM strip technique enabled the specimen to outperform the structural performance of the control specimen while strengthening the joints using externally bonded CFRP strips and sheets failed to restore the strengthened joints capacity.

  11. Strengthening of defected beam-column joints using CFRP.

    Science.gov (United States)

    Mahmoud, Mohamed H; Afefy, Hamdy M; Kassem, Nesreen M; Fawzy, Tarek M

    2014-01-01

    This paper presents an experimental study for the structural performance of reinforced concrete (RC) exterior beam-column joints rehabilitated using carbon-fiber-reinforced polymer (CFRP). The present experimental program consists of testing 10 half-scale specimens divided into three groups covering three possible defects in addition to an adequately detailed control specimen. The considered defects include the absence of the transverse reinforcement within the joint core, insufficient bond length for the beam main reinforcement and inadequate spliced implanted column on the joint. Three different strengthening schemes were used to rehabilitate the defected beam-column joints including externally bonded CFRP strips and sheets in addition to near surface mounted (NSM) CFRP strips. The failure criteria including ultimate capacity, mode of failure, initial stiffness, ductility and the developed ultimate strain in the reinforcing steel and CFRP were considered and compared for each group for the control and the CFRP-strengthened specimens. The test results showed that the proposed CFRP strengthening configurations represented the best choice for strengthening the first two defects from the viewpoint of the studied failure criteria. On the other hand, the results of the third group showed that strengthening the joint using NSM strip technique enabled the specimen to outperform the structural performance of the control specimen while strengthening the joints using externally bonded CFRP strips and sheets failed to restore the strengthened joints capacity. PMID:25685473

  12. Strengthening of defected beam–column joints using CFRP

    Science.gov (United States)

    Mahmoud, Mohamed H.; Afefy, Hamdy M.; Kassem, Nesreen M.; Fawzy, Tarek M.

    2013-01-01

    This paper presents an experimental study for the structural performance of reinforced concrete (RC) exterior beam–column joints rehabilitated using carbon-fiber-reinforced polymer (CFRP). The present experimental program consists of testing 10 half-scale specimens divided into three groups covering three possible defects in addition to an adequately detailed control specimen. The considered defects include the absence of the transverse reinforcement within the joint core, insufficient bond length for the beam main reinforcement and inadequate spliced implanted column on the joint. Three different strengthening schemes were used to rehabilitate the defected beam–column joints including externally bonded CFRP strips and sheets in addition to near surface mounted (NSM) CFRP strips. The failure criteria including ultimate capacity, mode of failure, initial stiffness, ductility and the developed ultimate strain in the reinforcing steel and CFRP were considered and compared for each group for the control and the CFRP-strengthened specimens. The test results showed that the proposed CFRP strengthening configurations represented the best choice for strengthening the first two defects from the viewpoint of the studied failure criteria. On the other hand, the results of the third group showed that strengthening the joint using NSM strip technique enabled the specimen to outperform the structural performance of the control specimen while strengthening the joints using externally bonded CFRP strips and sheets failed to restore the strengthened joints capacity. PMID:25685473

  13. Fatigue Behaviour of CFRP Strengthened Out-of-Plane Gusset Welded Joints with Double Cracks

    Directory of Open Access Journals (Sweden)

    Qian-Qian Yu

    2015-09-01

    Full Text Available This paper investigates the fatigue behaviour of out-of-plane gusset welded joints strengthened with carbon fibre reinforced polymer (CFRP laminates. Two notches were introduced at the weld toes adjacent to longitudinal plate ends to simulate the initial damage. Variables including the stress range, single- or double-sided strengthening and modulus of CFRP materials were considered. It was found that both cracks propagated under fatigue loading. All the specimens fractured along one predefined notch when the fatigue crack reached a certain length while the other crack also grew to some extent. Test results showed that the addition of composite materials significantly prolonged the fatigue life of specimens by as much as 1.28 to 8.17 times. Double-sided bond and ultra-high modulus CFRP materials led to a better strengthening efficiency. Thereafter, a series of numerical analyses were performed to study the stress intensity factor (SIF and crack opening displacement (COD. Local debonding around the crack tip at the adhesive-steel interface was taken into consideration. Finally, the fatigue life of all the specimens was evaluated based on the linear elastic fracture mechanism (LEFM theory and the predicted results agreed well with the experimental data.

  14. Cost-reduction method for delamination monitoring using electrical resistance changes of CFRP beam

    Science.gov (United States)

    Todoroki, A.; Ueda, M.

    2004-02-01

    Delamination is a significant defect of laminated composites. The present study employs an electrical resistance change method in an attempt to identify internal delaminations experimentally. The method adopts reinforcing carbon fibers as sensors. In our previous paper, an actual delamination crack in a Carbon Fiber Reinforced Plastics (CFRP) laminate was experimentally identified with artificial neural networks (ANN) or response surfaces created from a large number of experiments. The experimental results were used for learning of the ANN or regression of the response surfaces. For the actual application of the method, it is indispensable to reduce the number of experiments to suppress the total experimental cost. In the present study, therefore, FEM analyses are employed to make sets of data for learning of the ANN. First, electrical conductivity of the CFRP laminate is identified by means of the least estimation error method. After that, the results of FEM analyses are used for learning of the ANN. The method is applied to actual delamination monitoring of CFRP beams. As a result, the method successfully monitored the delamination location and size only with ten experiments.

  15. Quantitative impact characterization of aeronautical CFRP materials with non-destructive testing methods

    Energy Technology Data Exchange (ETDEWEB)

    Kiefel, Denis, E-mail: Denis.Kiefel@airbus.com, E-mail: Rainer.Stoessel@airbus.com; Stoessel, Rainer, E-mail: Denis.Kiefel@airbus.com, E-mail: Rainer.Stoessel@airbus.com [Airbus Group Innovations, Munich (Germany); Grosse, Christian, E-mail: Grosse@tum.de [Technical University Munich (Germany)

    2015-03-31

    In recent years, an increasing number of safety-relevant structures are designed and manufactured from carbon fiber reinforced polymers (CFRP) in order to reduce weight of airplanes by taking the advantage of their specific strength into account. Non-destructive testing (NDT) methods for quantitative defect analysis of damages are liquid- or air-coupled ultrasonic testing (UT), phased array ultrasonic techniques, and active thermography (IR). The advantage of these testing methods is the applicability on large areas. However, their quantitative information is often limited on impact localization and size. In addition to these techniques, Airbus Group Innovations operates a micro x-ray computed tomography (μ-XCT) system, which was developed for CFRP characterization. It is an open system which allows different kinds of acquisition, reconstruction, and data evaluation. One main advantage of this μ-XCT system is its high resolution with 3-dimensional analysis and visualization opportunities, which enables to gain important quantitative information for composite part design and stress analysis. Within this study, different NDT methods will be compared at CFRP samples with specified artificial impact damages. The results can be used to select the most suitable NDT-method for specific application cases. Furthermore, novel evaluation and visualization methods for impact analyzes are developed and will be presented.

  16. Acoustic Emission Monitoring of Lightning-Damaged CFRP Laminates during Compression-after-Impact Test

    International Nuclear Information System (INIS)

    Carbon-fiber reinforced plastic(CFRP) laminates made of nano-particle-coated carbon fibers and damaged by a simulated lightning strike were tested under compression-after-impact(CAI) mode, during which the damage progress due to compressive loading has been monitored by acoustic emission(AE). The impact damage was induced not by mechanical loading but by a simulated lightning strike. Conductive nano-particles were coated directly on the fibers, from which CFRP coupons were made. The coupon were subjected to the strikes with a high voltage/current impulse of 10-40 kA within a few . The effects of nano-particle coating and the degree of damage induced by the simulated lightning strikes on AE activities were examined, and the relationship between the compressive residual strength and AE behavior has been evaluated in terms of AE event counts and the onset of AE activity with the compressive loading. The degree of impact damage was also measured in terms of damage area by using ultrasonic C-scan images. The assessment during the CAI tests of damaged CFRP showed that AE monitoring appeared to be useful to differentiate the degree of damage hence the mechanical integrity of composite structures damaged by lightning strikes.

  17. A review on the development and properties of continuous fiber/epoxy/aluminum hybrid composites for aircraft structures

    Directory of Open Access Journals (Sweden)

    Edson Cocchieri Botelho

    2006-09-01

    Full Text Available Weight reduction and improved damage tolerance characteristics were the prime drivers to develop new family of materials for the aerospace/aeronautical industry. Aiming this objective, a new lightweight Fiber/Metal Laminate (FML has been developed. The combination of metal and polymer composite laminates can create a synergistic effect on many properties. The mechanical properties of FML shows improvements over the properties of both aluminum alloys and composite materials individually. Due to their excellent properties, FML are being used as fuselage skin structures of the next generation commercial aircrafts. One of the advantages of FML when compared with conventional carbon fiber/epoxy composites is the low moisture absorption. The moisture absorption in FML composites is slower when compared with polymer composites, even under the relatively harsh conditions, due to the barrier of the aluminum outer layers. Due to this favorable atmosphere, recently big companies such as EMBRAER, Aerospatiale, Boing, Airbus, and so one, starting to work with this kind of materials as an alternative to save money and to guarantee the security of their aircrafts.

  18. Active deformation and engineering analysis of CFRP mirror of various lay-up sequences within quasi-isotropic laminates

    Science.gov (United States)

    Zeng, Chunmei; Yu, Xia; Guo, Peiji

    2014-08-01

    A regularization stiffness coefficient method was verified further to optimize lay-up sequences of quasi-isotropic laminates for carbon fiber reinforced polymer (CFRP) composite mirrors. Firstly, the deformation due to gravity of 1G and temperature difference of 20-100°C and the modal were analyzed by finite element method (FEM). Secondly, the influence of angle error of ply stacking on quasi-isotropic of bending stiffness was evaluated. Finally, an active support system of 49 actuators in circular arrangement is designed for a 500mm CFRP mirror, and its goal is to deform the spherical CFRP mirror to a parabolic. Therefore, the response functions of the actuators were gotten, and the surface form errors and stresses were calculated and analyzed. The results show that the CFRP mirrors designed by the method have a better symmetrical bending deformation under gravity and thermal load and a higher fundamental frequency, and the larger n the better symmetry (for π/n quasi-isotropic laminates); the method reduces the sensitivity to misalignment of ply orientation for symmetric bending, and the mirror's maximum von Mises stress and maximum shear stress are less compared to those laminates not optimized in lay-up sequence.

  19. Experimental Investigation on Shear Resistance Behaviour of RC Precracked and Non-Precracked T-Beams using Discrete CFRP Strips

    Directory of Open Access Journals (Sweden)

    J. Jayaprakash

    2009-12-01

    Full Text Available The exploitation of Fibre Reinforced Polymer (FRP composites as external reinforcement is an evergreen technique for improving the structural performance of the existing Reinforced Concrete (RC structures. This paper presents a experimental investigation on shear strengthening capacity and modes of failure of precracked and non-precracked RC beams bonded externally with bi-directional Carbon Fibre Reinforced Polymer (CFRP fabric strips. Twelve RC T- beams were fabricated with different internal longitudinal and shear reinforcements. These beams were subjected to two types of loading; namely three point and four point bending systems. The beams were classified into three categories namely control, precracked-repaired, and initially strengthened (i.e. non-precracked beams. Prior to the application of CFRP shear reinforcement, the precracked-repaired beams were partially loaded to develop shear cracks along the shear spans, whereas the initially strengthened beams were strengthened with CFRP reinforcement without the application of any preloading. The overall increase in shear enhancement of the precracked-repaired and initially strengthened beams ranged between 13% and 61% greater over their control beams. It was found that the application of CFRP strips in the precracked-repaired beams attained better performance as compared to the initially strengthened beams.

  20. The effects of aircraft fuel and fluids on the strength properties of Resin Transfer Molded (RTM) composites

    Science.gov (United States)

    Falcone, Anthony; Dow, Marvin B.

    1993-01-01

    The resin transfer molding (RTM) process offers important advantages for cost-effective composites manufacturing, and consequently has become the subject of intense research and development efforts. Several new matrix resins have been formulated specifically for RTM applications in aircraft and aerospace vehicles. For successful use on aircraft, composite materials must withstand exposure to the fluids in common use. The present study was conducted to obtain comparative screening data on several state-ofthe-art RTM resins after environmental exposures were performed on RTM composite specimens. Four graphite/epoxy composites and one graphite/bismaleimide composite were tested; testing of two additional graphite epoxy composites is in progress. Zero-deg tension tests were conducted on specimens machined from eight-ply (+45-deg, -45-deg) laminates, and interlaminar shear tests were conducted on 32-ply 0-deg laminate specimens. In these tests, the various RTM resins demonstrated widely different strengths, with 3501-6 epoxy being the strongest. As expected, all of the matrix resins suffered severe strength degradation from exposure to methylene chloride (paint stripper). The 3501-6 epoxy composites exhibited about a 30 percent drop in tensile strength in hot, wet tests. The E905-L epoxy exhibited little loss of tensile strength (less than 8 percent) after exposure to water. The CET-2 and 862 epoxies as well as the bismaleimide exhibited reduced strengths at elevated temperature after exposure to oils and fuel. In terms of the percentage strength reductions, all of the RTM matrix resins compared favorably with 3501-6 epoxy.

  1. Confining concrete with sisal and jute FRP as alternatives for CFRP and GFRP

    Directory of Open Access Journals (Sweden)

    Tara Sen

    2015-12-01

    Full Text Available This research paper presents an experimental investigation on the confinement strength and confinement modulus of concrete cylinders confined using different types of natural fibre composites and a comparative performance analysis with different artificial fibre based composite materials. The paper also highlights the need to switch over from the utilization of artificial fibres, which are non-renewable and fossil fuel products, to environmental beneficial materials like green fibres. The utilization of plant products like sisal and jute fibres and their composites in various structural engineering applications addresses the issues of sustainability and renewability with constructional materials. The paper describes a suitable mechanical treatment method like high temperature conditioning, which aids us in further improving the properties of these woven natural materials like sisal and jute for composite fabrication and utilization. Heat treated natural fibres of woven sisal and jute were utilized for confining concrete cylinders similar to CFRP and GFRP confinement and their confinement characteristics were obtained and compared. All the cylinders were subjected to monotonic axial compressive loads, so as to evaluate the effect of confinement on the axial load carrying capacity and all their failure modes were discussed thoroughly. The results indicated superior performance by sisal FRP as well as jute FRP confined cylinders as compared to controlled or unconfined cylinders, also sisal FRP wrapped cylinders displayed ultimate axial load of comparable magnitude to CFRP confinement. Natural FRP confinement displayed superior confinement modulus and confinement strength, also the ultimate axial load of concrete cylinders confined with natural FRPs underwent 66% enhancement by sisal FRP and 48% enhancement by jute FRP, in comparison with controlled or unconfined cylinders. Enhancement in axial load carrying capacity was 83% with CFRP confinement

  2. Behaviour of RC beams shear strengthening with NSM CFRP laminates

    OpenAIRE

    Dias, Salvador J. E.; Barros, Joaquim A. O.

    2008-01-01

    The effectiveness of the Near Surface Mounted (NSM) technique with Carbon Fiber Reinforced Polymer (CFRP) laminates for the shear strengthening of T cross section reinforced concrete (RC) beams is assessed by experimental research. The influence of the percentage and inclination of CFRP laminates on the shear strengthening contribution was evaluated. The experimental program also includes beams strengthened according to the externally bonded reinforcement (EBR) technique in ord...

  3. A preliminary design study of a laminar flow control wing of composite materials for long range transport aircraft

    Science.gov (United States)

    Swinford, G. R.

    1976-01-01

    The results of an aircraft wing design study are reported. The selected study airplane configuration is defined. The suction surface, ducting, and compressor systems are described. Techniques of manufacturing suction surfaces are identified and discussed. A wing box of graphite/epoxy composite is defined. Leading and trailing edge structures of composite construction are described. Control surfaces, engine installation, and landing gear are illustrated and discussed. The preliminary wing design is appraised from the standpoint of manufacturing, weight, operations, and durability. It is concluded that a practical laminar flow control (LFC) wing of composite material can be built, and that such a wing will be lighter than an equivalent metal wing. As a result, a program of suction surface evaluation and other studies of configuration, aerodynamics, structural design and manufacturing, and suction systems are recommended.

  4. INTEGRITY OF GLASS/EPOXY AIRCRAFT COMPOSITE PART REPAIRED USING FIVE DIFFERENT METHODS

    Directory of Open Access Journals (Sweden)

    IEA AGHACHI

    2013-01-01

    Full Text Available Aircraft repairs are considered permanent repairs. This type of permanent repair is time- consuming and needs to be accomplished in a well-guided specification and precise accuracy. The critical demand for aircraft repaired part is to meet the integrity of the original parent body while in-service, which does not give room for trial anderror. Similarly, the cost of discarding parts that have minor to medium surface damage is very high. In this work, an experimental work was carried out to find other viable repair method that could be applied to surface repair of an aircraft. It was found that the pre-preg method is still the most preferred. The infusion process, ifperformed under well-controlled environment, can be good substitute for wet layup.

  5. The Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS mission: design, execution, and first results

    Directory of Open Access Journals (Sweden)

    D. J. Jacob

    2010-06-01

    Full Text Available The NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS mission was conducted in two 3-week deployments based in Alaska (April 2008 and western Canada (June–July 2008. Its goal was to better understand the factors driving current changes in Arctic atmospheric composition and climate, including (1 influx of mid-latitude pollution, (2 boreal forest fires, (3 aerosol radiative forcing, and (4 chemical processes. The June–July deployment was preceded by one week of flights over California (ARCTAS-CARB focused on (1 improving state emission inventories for greenhouse gases and aerosols, (2 providing observations to test and improve models of ozone and aerosol pollution. ARCTAS involved three aircraft: a DC-8 with a detailed chemical payload, a P-3 with an extensive aerosol and radiometric payload, and a B-200 with aerosol remote sensing instrumentation. The aircraft data augmented satellite observations of Arctic atmospheric composition, in particular from the NASA A-Train. The spring phase (ARCTAS-A revealed pervasive Asian pollution throughout the Arctic as well as significant European pollution below 2 km. Unusually large Siberian fires in April 2008 caused high concentrations of carbonaceous aerosols and also affected ozone. Satellite observations of BrO column hotspots were found not to be related to Arctic boundary layer events but instead to tropopause depressions, suggesting the presence of elevated inorganic bromine (5–10 pptv in the lower stratosphere. Fresh fire plumes from Canada and California sampled during the summer phase (ARCTAS-B indicated low NOx emission factors from the fires, rapid conversion of NOx to PAN, no significant secondary aerosol production, and no significant ozone enhancements except when mixed with urban pollution.

  6. Analysis and Fabrication of Paraboloidal CFRP Sandwich Mirrors

    Science.gov (United States)

    Hong, Tayo Steve

    The low areal weight requirements of telescopes in aerospace applications has driven the study on composite mirrors for several years. For example, the primary parabolic mirror in a balloon-borne, Cassegrain telescope required an optical quality better than 30 microns in figure RMS error. A parametric study on composite sandwich mirrors was conducted by using finite element analysis as well as optical analysis. The factors covered the cell sizes, core materials, core thicknesses, face layups, and support configurations. Based on theoretical calculations, many high quality spherical composite sandwich mirrors were generated by using a non-heat curing process. The CFRP faces and Nomex core were chosen as the baseline materials for mirror fabrication due to their high strength and low weight. The proposed replication method applied an interface layer between face and surface coat to eliminate print -through problems. Many important goals have been realized in those mirror samples with optical laser interferometer testing. These include the figure RMS error less than 2 microns and the surface RMS error less than 0.05 micron. The areal weights of the mirror samples are less than 7 kg/m ^2. The thermal stability of these mirrors was observed from the optical results with thermal cycling tests. The proposed 2-meter parabolic composite sandwich mirror, with an areal weight of less than 10 kg/m ^2, would consist of either (0/90/45/ -45) _{rm S} layup faces with an optimal 3^{' '} core or (QC) layup faces with a total core thickness of 5 inches. Both a ring support around the equator and the 18-point Hindle-type support would lead to the best optical quality under both self weight and thermal loading.

  7. Full-scale testing, production and cost analysis data for the advanced composite stabilizer for Boeing 737 aircraft. Volume 1: Technical summary

    Science.gov (United States)

    Aniversario, R. B.; Harvey, S. T.; Mccarty, J. E.; Parsons, J. T.; Peterson, D. C.; Pritchett, L. D.; Wilson, D. R.; Wogulis, E. R.

    1983-01-01

    The full scale ground test, ground vibration test, and flight tests conducted to demonstrate a composite structure stabilizer for the Boeing 737 aircraft and obtain FAA certification are described. Detail tools, assembly tools, and overall production are discussed. Cost analyses aspects covered include production costs, composite material usage factors, and cost comparisons.

  8. Effects of Z-pins on Lamb waves in composite plates

    Science.gov (United States)

    Swenson, Eric D.; Kapoor, Hitesh; Soni, Som R.

    2010-04-01

    This experimental research investigates the effects of adding z-pins to a carbon fiber reinforced plate (CFRP) on Lamb wave propagation, such as mode conversion and reflections. The motivation for this study is derived from the current and expected future use of z-pins in aircraft structures coupled with the requirement to design structural health monitoring (SHM) systems for detecting damage in regions of composite structures with z-pins. This experimental study is conducted on two 4.8 mm thick CFRP test articles, where one plate has a 20 by 279 mm2 band of z-pins and the other does not. The z-pins have an average diameter of 0.28 mm and are inserted through the thickness of the panel with an area density of 4% before curing. A three-dimensional (3D) laser Doppler vibrometer (LDV) was employed to collect velocity measurements over a 1 mm uniformly-spaced grid of 17,899 scan points. Time-sequenced 3D LDV scans are presented to show that adding this relatively small amount of z-pins to a 4.8 mm thick CFRP has few measureable effects on Lamb wave propagation.

  9. Infrared thermography for CFRP inspection: computational model and experimental results

    Science.gov (United States)

    Fernandes, Henrique C.; Zhang, Hai; Morioka, Karen; Ibarra-Castanedo, Clemente; López, Fernando; Maldague, Xavier P. V.; Tarpani, José R.

    2016-05-01

    Infrared Thermography (IRT) is a well-known Non-destructive Testing (NDT) technique. In the last decades, it has been widely applied in several fields including inspection of composite materials (CM), specially the fiber-reinforced polymer matrix ones. Consequently, it is important to develop and improve efficient NDT techniques to inspect and assess the quality of CM parts in order to warranty airworthiness and, at the same time, reduce costs of airline companies. In this paper, active IRT is used to inspect carbon fiber-reinforced polymer (CFRP) at laminate with artificial inserts (built-in sample) placed on different layers prior to the manufacture. Two optical active IRT are used. The first is pulsed thermography (PT) which is the most widely utilized IRT technique. The second is a line-scan thermography (LST) technique: a dynamic technique, which can be employed for the inspection of materials by heating a component, line-by-line, while acquiring a series of thermograms with an infrared camera. It is especially suitable for inspection of large parts as well as complex shaped parts. A computational model developed using COMSOL Multiphysics® was used in order to simulate the inspections. Sequences obtained from PT and LST were processed using principal component thermography (PCT) for comparison. Results showed that it is possible to detect insertions of different sizes at different depths using both PT and LST IRT techniques.

  10. Process-induced Distortions in CFRP Manufacturing: A bottle-neck for high-rate Production Scenarios

    OpenAIRE

    Kappel, Erik; Stefaniak, Daniel; Hühne, Christian

    2014-01-01

    Undesired process-induced distortions (PID) are an inherent issue in today's CFRP manufacturing scenarios. Distortions are inevitable due to an interaction of composite-specific and process-specific parameters. In academia it is distinguished in three main phenomena Spring-in, Warpage and Forced- interaction while their specific relevance depends on the part shape at hand. As process distortions remain widely unconsidered in current partdevelopment chains, they induce considera...

  11. Experimental Investigation on Shear Resistance Behaviour of RC Precracked and Non-Precracked T-Beams using Discrete CFRP Strips

    OpenAIRE

    J. Jayaprakash; Abdul Samad, A. A.; A.A. Ashrabov; K.K. Choong

    2009-01-01

    The exploitation of Fibre Reinforced Polymer (FRP) composites as external reinforcement is an evergreen technique for improving the structural performance of the existing Reinforced Concrete (RC) structures. This paper presents a experimental investigation on shear strengthening capacity and modes of failure of precracked and non-precracked RC beams bonded externally with bi-directional Carbon Fibre Reinforced Polymer (CFRP) fabric strips. Twelve RC T- beams were fabricated with different int...

  12. Properties of Multifunctional Hybrid Carbon Nanotube/Carbon Fiber Polymer Matrix Composites

    Science.gov (United States)

    Cano, Roberto J.; Kang, Jin Ho; Grimsley, Brian W.; Ratcliffe, James G.; Siochi, Emilie J.

    2016-01-01

    For aircraft primary structures, carbon fiber reinforced polymer (CFRP) composites possess many advantages over conventional aluminum alloys due to their light weight, higher strength- and stiffness-to-weight ratios, and low life-cycle maintenance costs. However, the relatively low electrical and thermal conductivities of CFRP composites fail to provide structural safety in certain operational conditions such as lightning strikes. Carbon nanotubes (CNT) offer the potential to enhance the multi-functionality of composites with improved thermal and electrical conductivity. In this study, hybrid CNT/carbon fiber (CF) polymer composites were fabricated by interleaving layers of CNT sheets with Hexcel® IM7/8852 prepreg. Resin concentrations from 1 wt% to 50 wt% were used to infuse the CNT sheets prior to composite fabrication. The interlaminar properties of the resulting hybrid composites were characterized by mode I and II fracture toughness testing. Fractographical analysis was performed to study the effect of resin concentration. In addition, multi-directional physical properties like thermal conductivity of the orthotropic hybrid polymer composite were evaluated.

  13. Analytical and experimental investigation of aircraft metal structures reinforced with filamentary composites. Phase 1: Concept development and feasibility

    Science.gov (United States)

    Oken, S.; June, R. R.

    1971-01-01

    The analytical and experimental investigations are described in the first phase of a program to establish the feasibility of reinforcing metal aircraft structures with advanced filamentary composites. The interactions resulting from combining the two types of materials into single assemblies as well as their ability to function structurally were studied. The combinations studied were boron-epoxy reinforced aluminum, boron-epoxy reinforced titanium, and boron-polyimide reinforced titanium. The concepts used unidirectional composites as reinforcement in the primary loading direction and metal for carrying the transverse loads as well as its portion of the primary load. The program established that several realistic concepts could be fabricated, that these concepts could perform to a level that would result in significant weight savings, and that there are means for predicting their capability within a reasonable degree of accuracy. This program also encountered problems related to the application of polyimide systems that resulted in their relatively poor and variable performance.

  14. Program for establishing long-time flight service performance of composite materials in the center wing structure of C-130 aircraft. Phase 5: Flight service and inspection

    Science.gov (United States)

    Kizer, J. A.

    1981-01-01

    Inspections of the C-130 composite-reinforced center wings were conducted over the flight service monitoring period of more than six years. Twelve inspections were conducted on each of the two C-130H airplanes having composite reinforced center wing boxes. Each inspection consisted of visual and ultrasonic inspection of the selective boron-epoxy reinforced center wings which included the inspection of the boron-epoxy laminates and the boron-epoxy reinforcement/aluminum structure adhesive bondlines. During the flight service monitoring period, the two C-130H aircraft accumulated more than 10,000 flight hours and no defects were detected in the inspections over this period. The successful performance of the C-130H aircraft with composite-reinforced center wings allowed the transfer of the responsibilities of inspecting and maintaining these two aircraft to the U. S. Air Force.

  15. Strut deformation in CFRP-strengthened reinforced concrete deep beams.

    Science.gov (United States)

    Panjehpour, Mohammad; Chai, Hwa Kian; Voo, Yen Lei

    2014-01-01

    Strut-and-tie model (STM) method evolved as one of the most useful designs for shear critical structures and discontinuity regions (D-regions). It provides widespread applications in the design of deep beams as recommended by many codes. The estimation of bottle-shaped strut dimensions, as a main constituent of STM, is essential in design calculations. The application of carbon fibre reinforced polymer (CFRP) as lightweight material with high tensile strength for strengthening D-regions is currently on the increase. However, the CFRP-strengthening of deep beam complicates the dimensions estimation of bottle-shaped strut. Therefore, this research aimed to investigate the effect of CFRP-strengthening on the deformation of RC strut in the design of deep beams. Two groups of specimens comprising six unstrengthened and six CFRP-strengthened RC deep beams with the shear span to the effective depth ratios (a/d) of 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00 were constructed in this research. These beams were tested under four-point bending configuration. The deformation of struts was experimentally evaluated using the values of strain along and perpendicular to the strut centreline. The evaluation was made by the comparisons between unstrengthened and CFRP-strengthened struts regarding the widening and shortening. The key variables were a/d ratio and applied load level. PMID:25197698

  16. Strengthening Reinforced Concrete Beams with CFRP and GFRP

    Directory of Open Access Journals (Sweden)

    Mehmet Mustafa Önal

    2014-01-01

    Full Text Available Concrete beams were strengthened by wrapping the shear edges of the beams twice at 45° in opposite directions by either carbon fiber reinforced polymer (CFRP or glass fiber reinforced polymer (GFRP. The study included 3 CFRP wrapped beams, 3 GFRP wrapped beams, and 3 control beams, all of which were 150 × 250 × 2200 mm and manufactured with C20 concrete and S420a structural steel at the Gazi University Technical Education Faculty labs, Turkey. Samples in molds were cured by watering in the open air for 21 days. Four-point bending tests were made on the beam test specimens and the data were collected. Data were evaluated in terms of load displacement, bearing strength, ductility, and energy consumption. In the CFRP and GFRP reinforced beams, compared to controls, 38% and 42%, respectively, strength increase was observed. In all beams, failure-flexural stress occurred in the center as expected. Most cracking was observed in the flexural region 4. A comparison of CFRP and GFRP materials reveals that GFRP enforced parts absorb more energy. Both materials yielded successful results. Thicker epoxy application in both CFRP and GFRP beams was considered to be effective in preventing break-ups.

  17. Strut Deformation in CFRP-Strengthened Reinforced Concrete Deep Beams

    Directory of Open Access Journals (Sweden)

    Mohammad Panjehpour

    2014-01-01

    Full Text Available Strut-and-tie model (STM method evolved as one of the most useful designs for shear critical structures and discontinuity regions (D-regions. It provides widespread applications in the design of deep beams as recommended by many codes. The estimation of bottle-shaped strut dimensions, as a main constituent of STM, is essential in design calculations. The application of carbon fibre reinforced polymer (CFRP as lightweight material with high tensile strength for strengthening D-regions is currently on the increase. However, the CFRP-strengthening of deep beam complicates the dimensions estimation of bottle-shaped strut. Therefore, this research aimed to investigate the effect of CFRP-strengthening on the deformation of RC strut in the design of deep beams. Two groups of specimens comprising six unstrengthened and six CFRP-strengthened RC deep beams with the shear span to the effective depth ratios (a/d of 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00 were constructed in this research. These beams were tested under four-point bending configuration. The deformation of struts was experimentally evaluated using the values of strain along and perpendicular to the strut centreline. The evaluation was made by the comparisons between unstrengthened and CFRP-strengthened struts regarding the widening and shortening. The key variables were a/d ratio and applied load level.

  18. Aerodynamic stability of cable-supported bridges using CFRP cables

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xin-jun; YING Lei-dong

    2007-01-01

    To gain understanding of the applicability of carbon fiber reinforced polymer (CFRP) cable in cable-supported bridges, based on the Runyang Bridge and Jinsha Bridge, a suspension bridge using CFRP cables and a cable-stayed bridge using CFRP stay cables are designed, in which the cable's cross-sectional area is determined by the principle of equivalent axial stiffness.Numerical investigations on the aerodynamic stability of the two bridges are conducted by 3D nonlinear aerodynamic stability analysis. The results showed that as CFRP cables are used in cable-supported bridges, for suspension bridge, its aerodynamic stability is superior to that of the case using steel cables due to the great increase of the torsional frequency; for cable-stayed bridge,its aerodynamic stability is basically the same as that of the case using steel stay cables. Therefore as far as the wind stability is considered, the use of CFRP cables in cable-supported bridges is feasible, and the cable's cross-sectional area should be determined by the principle of equivalent axial stiffness.

  19. Study of the Tensile Properties of CFRP Strengthened Steel Plates

    Directory of Open Access Journals (Sweden)

    Yiyan Lu

    2015-12-01

    Full Text Available This paper presents the experimental results of steel plates strengthened with carbon fiber reinforced polymer (CFRP sheets under tensile load. The number of CFRP layers (ranging from one to four, strengthening schemes (single-sided and double-sided bonding, and temperatures (ranging from 25 to 120 °C were investigated. Results showed that the number of CFRP layers and strengthening schemes had insignificant effects on failure modes of specimens. The failure modes were dominated by the degradation of resin matrix at temperatures lower than Tg + 10 or 20 °C, where Tg is the glass transition temperature, and were dominated by the volume decrease of resin matrix at temperatures above that. Through bonding CFRP sheets, the ultimate load and post-elastic stiffness of specimens were significantly increased. However, the increase in the number of CFRP layers also led to the decrease in strengthening and stiffening efficiency. The double-sided strengthened specimens showed more preferable mechanical properties than the single-sided strengthened specimens. As temperature increased, significant decreases in ultimate load and post-elastic stiffness were observed. Analytical modeling to predict the mechanical properties at ambient and elevated temperatures were conducted, respectively. The modeling results were verified by the test data.

  20. Strut Deformation in CFRP-Strengthened Reinforced Concrete Deep Beams

    Science.gov (United States)

    Panjehpour, Mohammad; Chai, Hwa Kian; Voo, Yen Lei

    2014-01-01

    Strut-and-tie model (STM) method evolved as one of the most useful designs for shear critical structures and discontinuity regions (D-regions). It provides widespread applications in the design of deep beams as recommended by many codes. The estimation of bottle-shaped strut dimensions, as a main constituent of STM, is essential in design calculations. The application of carbon fibre reinforced polymer (CFRP) as lightweight material with high tensile strength for strengthening D-regions is currently on the increase. However, the CFRP-strengthening of deep beam complicates the dimensions estimation of bottle-shaped strut. Therefore, this research aimed to investigate the effect of CFRP-strengthening on the deformation of RC strut in the design of deep beams. Two groups of specimens comprising six unstrengthened and six CFRP-strengthened RC deep beams with the shear span to the effective depth ratios (a/d) of 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00 were constructed in this research. These beams were tested under four-point bending configuration. The deformation of struts was experimentally evaluated using the values of strain along and perpendicular to the strut centreline. The evaluation was made by the comparisons between unstrengthened and CFRP-strengthened struts regarding the widening and shortening. The key variables were a/d ratio and applied load level. PMID:25197698

  1. Study on Design of High Efficiency and Light Weight Composite Propeller Blade for a Regional Turboprop Aircraft

    Science.gov (United States)

    Kong, Changduk; Lee, Kyungsun

    2013-03-01

    In this study, aerodynamic and structural design of the composite propeller blade for a regional turboprop aircraft is performed. The thin and wide chord propeller blade of high speed turboprop aircraft should have proper strength and stiffness to carry various kinds of loads such as high aerodynamic bending and twisting moments and centrifugal forces. Therefore the skin-spar-foam sandwich structure using high strength and stiffness carbon/epoxy composite materials is used to improve the lightness. A specific design procedure is proposed in this work as follows; firstly the aerodynamic configuration design, which is acceptable for the design requirements, is carried out using the in-house code developed by authors, secondly the structure design loads are determined through the aerodynamic load case analysis, thirdly the spar flange and the skin are preliminarily sized by consideration of major bending moments and shear forces using both the netting rule and the rule of mixture, and finally, the stress analysis is performed to confirm the structural safety and stability using finite element analysis commercial code, MSC. NASTRAN/PATRAN. Furthermore the additional analysis is performed to confirm the structural safety due to bird strike impact on the blade during flight operation using a commercial code, ANSYS. To realize the proposed propeller design, the prototype blades are manufactured by the following procedure; the carbon/epoxy composite fabric prepregs are laid up for skin and spar on a mold using the hand lay-up method and consolidated with a proper temperature and vacuum in the oven. To finalize the structural design, the full-scale static structural test is performed under the simulated aerodynamic loads using 3 point loading method. From the experimental results, it is found that the designed blade has a good structural integrity, and the measured results agree well with the analytical results as well.

  2. Preliminary weight and cost estimates for transport aircraft composite structural design concepts

    Science.gov (United States)

    1973-01-01

    Preliminary weight and cost estimates have been prepared for design concepts utilized for a transonic long range transport airframe with extensive applications of advanced composite materials. The design concepts, manufacturing approach, and anticipated details of manufacturing cost reflected in the composite airframe are substantially different from those found in conventional metal structure and offer further evidence of the advantages of advanced composite materials.

  3. Finite element simulation and testing of ISW CFRP anchorage

    DEFF Research Database (Denmark)

    Schmidt, Jacob Wittrup; Goltermann, Per; Hertz, Kristian Dahl

    2013-01-01

    Several Carbon Fibre Reinforced Polymers (CFRP) systems have been used successfully for strengthening of structures during the last decades. However, the fracture often occurs in the concrete adherent or in the adhesive interface when used for steel strengthening. As a consequence the CFRP...... to the remaining structure. However, reaching the full capacity of the CFRP material is difficult since anchoring often courses premature failure modes such as crushing of the Fibre Reinforced Polymers (FRP), slip in the FRP and adjacent adherent, cutting of the fibres, bending of fibres and frontal overload...... is modelled in the 3D finite Element program ABAQUS, just as digital image correlation (DIC) testing was performed to verify the finite element simulation. Also a new optimized design was produced to ensure that the finite element simulation and anchorage behaviour correlated well. It is seen...

  4. A study on non-contact ultrasonic technique for on-line inspection of CFRP

    International Nuclear Information System (INIS)

    The advantages of carbon fiber reinforced plastic materials (CFRP) are: they are light structure materials, they have corrosion resistance, and higher specific strength and elasticity. The recently developed 3-dimentional fiber placement system is able to produce a more complex and various shaped structures due to less limitations of a product shape according to the problem in conventional fabrication process. This fiber placement system stacks the narrow prepreg tape on the mold according to the designed sequence and thickness. Non-destructive evaluation was rquired for these composites to evaluate changes in strength caused by defects such as delamination and porosity. Additionally, the expectent quality should be satisfied for the high cost fabrication process using the fiber placement system. Therefore, an on line non-destructive evaluation system is required and real-time complement is needed when the defects are detected [1]. Defect imaging by the ultrasonic C-scan method is a useful technique for defect detection in CFRP. However, the conventional ultrasonic C-scan technique cannot be applied during the fabrication process because the test piece should be immersed into the water. Therefore, non-contact ultrasonic techniques should be applied during the fabricating process. For the development of non-contact ultrasonic techniques available in non-destructive evaluation of CFRP, a recent laser-generated ultrasonic technique and an air-coupled transducer that transmit and receive ultrasounds in the air are studied [2-3]. In this study, generating and receiving techniques of laser-generated ultrasound and the characteristics of received signals upon the internal defects of CFRO were studied for non-contact inspection

  5. Vibrational behavior of adaptive aircraft wing structures modelled as composite thin-walled beams

    Science.gov (United States)

    Song, O.; Librescu, L.; Rogers, C. A.

    1992-01-01

    The vibrational behavior of cantilevered aircraft wings modeled as thin-walled beams and incorporating piezoelectric effects is studied. Based on the converse piezoelectric effect, the system of piezoelectric actuators conveniently located on the wing yield the control of its associated vertical and lateral bending eigenfrequencies. The possibility revealed by this study enabling one to increase adaptively the eigenfrequencies of thin-walled cantilevered beams could play a significant role in the control of the dynamic response and flutter of wing and rotor blade structures.

  6. Design of a Low-Cost Easy-to-Fly STOL Ultralight Aircraft in Composite Material

    Directory of Open Access Journals (Sweden)

    D. P. Coiro

    2005-01-01

    Full Text Available The paper deals with the design of an aircraft, starting from a market survey, the conceptual design loop and the preliminary choice of dimensions, and leading to the detailed design of efficient high-lift systems and a low-drag fuselage shape. Technological challenges regarding the design of low-cost systems for flap/slat retraction and a simple wing folding system are highlighted. Aiming at an efficient optimization algorithm, we developed a new integration technique between CAD, aerodynamic and structural numerical calculation. Examples deriving from this new approach are presented. 

  7. Flight service evaluation of kevlar-49 epoxy composite panels in wide-bodied commercial transport aircraft: Flight service report

    Science.gov (United States)

    Stone, R. H.

    1981-01-01

    Kevlar-49 fairing panels, installed as flight service components on three L-1011s, were inspected after 7 years service. There are six Kevlar-49 panels on each aircraft: a left hand and right hand set of a wing-body sandwich fairing; a slid laminate under-wing fillet panel; and a 422 K service aft engine fairing. The three L-1011s include one each in service with Eastern, Air Canada, and TWA. The fairings have accumulated a total of 52,500 hours, with one ship set having 17.700 hours service. The inspections were conducted at the airlines' major maintenance bases with the participation of Lockheed Engineering. The Kevlar-49 components were found to be performing satisfactorily in service with no major problems or any condition requiring corrective action. The only defects noted were minor impact damage and a minor degree of fastener hole fraying and elongation. These are for the most part comparable to damage noted on fiberglass fairings. The service history to date indicates that Kevlar-49 epoxy composite materials have satisfactory service characteristics for use in aircraft secondary structure.

  8. Testing and Analysis of a Composite Non-Cylindrical Aircraft Fuselage Structure. Part 1; Ultimate Design Loads

    Science.gov (United States)

    Przekop, Adam; Jegley, Dawn C.; Lovejoy, Andrew E.; Rouse, Marshall; Wu, Hsi-Yung T.

    2016-01-01

    The Environmentally Responsible Aviation Project aimed to develop aircraft technologies enabling significant fuel burn and community noise reductions. Small incremental changes to the conventional metallic alloy-based 'tube and wing' configuration were not sufficient to achieve the desired metrics. One airframe concept identified by the project as having the potential to dramatically improve aircraft performance was a composite-based hybrid wing body configuration. Such a concept, however, presented inherent challenges stemming from, among other factors, the necessity to transfer wing loads through the entire center fuselage section which accommodates a pressurized cabin confined by flat or nearly flat panels. This paper discusses finite element analysis and testing of a large-scale hybrid wing body center section structure developed and constructed to demonstrate that the Pultruded Rod Stitched Efficient Unitized Structure concept can meet these challenging demands of the next generation airframes. Part I of the paper considers the five most critical load conditions, which are internal pressure only and positive and negative g-loads with and without internal pressure. Analysis results are compared with measurements acquired during testing. Performance of the test article is found to be closely aligned with predictions and, consequently, able to support the hybrid wing body design loads in pristine and barely visible impact damage conditions.

  9. Thermomechanical responses of concrete members strengthened with cfrp sheets

    Science.gov (United States)

    Alqurashi, Abdulaziz

    Strengthening structural members means to be able to carry additional loads. Since, 1990s, a lot of materials and techniques have been established to not only increasing the capacity of member but also facing deterioration. Deterioration has become one of the worst highly maintenance cost. According to The ASCE, 27.1% of all bridges in the United States are not effectual. This is because the high traffic reflects negatively to structural members and cause deterioration of these members. This problem has been cost a lot of money. In addition, FRP has approved that it can increase the capacity of member and overcome some disadvantages such as deterioration. Therefore, CFRP sheet has become widely used. However, high temperatures affect the performance of externally bonded CFRP sheet negatively. Investigation should be carried out on relaxation and flexural performance of members under different temperatures. Therefore, this thesis focus on analyzing and investigating the performance of strengthened members exposed to elevated temperatures (25 to 175 °C). The experimental program was divided to two main parts. First, 144 strengthen concrete blocks 100mm X 150mm X 75mm has been exposed to elevated temperatures. These blocks have two main categories, which are different CFRP sheet width, and different CFRP sheet length. Different CFRP width has three types, which are type 0.25B (25mm x 100mm), type 0.5B (50mm x 100mm) and type 0.75B (75mm x 100mm). Also, Different CFRP length has three types, which are type L e (bonded area of 50 mm by 90mm), 1.25 Le (area of 50mm by 125mm) and type 1.5Le (50mm by 137 mm). Second, studying the performance of RC beams exposed to elevated temperatures.

  10. Small- and medium-scale effects of high-flying aircraft exhausts on the atmospheric composition

    Directory of Open Access Journals (Sweden)

    Y. E. Ozolin

    Full Text Available Following numerous model studies of the global impacts of sub- and supersonic aircraft on the atmosphere, this paper assesses the separate aircraft engine exhaust effects of the 45°N cruise flight and at the 10- and 18-km levels of the July atmosphere. A box diffusion photochemical model in the cross-section plane of the flight trajectory is used to compute the effects of gas-phase and heterogeneous reactions on the condensation trail particles in the troposphere, and on the sulphate aerosols in the stratosphere. The enhanced horizontal dispersion of the exhaust plume is considered in the model. A significant but short term depletion of ozone is predicted, which is 99% restored in about 1 h in the wide plume with enhanced horizontal dispersion, but requires more than 24 h in the narrow plume without it. The oxidation rate of NO and NO2 into the HNO3 depends on the OH content in the exhausts and varies in all the cases. The heterogeneous photochemistry has only a small influence on the initial evolution of N2O5 and HO2 in the plume.

  11. Shear Strengthening of Corbels with Carbon Fibre Reinforced Polymers (CFRP

    Directory of Open Access Journals (Sweden)

    Nawaz, A.

    2010-09-01

    Full Text Available Corbels constitute what are known as “disturbed” regions in concrete structures, where typical shear failure may be anticipated on the grounds of small shear span-to-depth ratios. The concentration of stress induced by the weight of girders on the very small loadbearing areas in corbels often causes cracking in bridges and other structures. Little experimental research can be found in the literature on the shear strengthening of corbels. In the present study, nine such members were tested. Two had no carbon fibre reinforced polymers attached, while CFRP laminates were externally bonded to the other seven, in a number of different spatial arrangements. Ultimate shear strength was found and compared for all specimens. The results showed that CFRP configuration and geometry directly affected corbel shear strength, which was higher in all the CFRPstrengthened corbels than in the controls. The highest strength values were recorded for specimens whose shear-critical area was wrapped in CFRP.

    Las ménsulas constituyen lo que conocemos como regiones de “distorsión” en las estructuras de hormigón, zonas en que pueden preverse roturas por cortante debido a las bajas relaciones luz de cortante-canto presentes en ellas. La concentración de solicitaciones producida por el peso de las vigas sobre superficies de carga muy reducidas en las ménsulas a menudo provoca el agrietamiento de puentes y otras estructuras de obra civil. En la literatura especializada sobre el refuerzo a cortante de las ménsulas existen escasos ejemplos de estudios experimentales. Para la presente investigación se han realizado ensayos con nueve elementos de este tipo. Dos de ellos no incluían polímeros reforzados con fibra de carbono (CFRP, mientras que los siete restantes llevaban láminas externas de CFRP, dispuestas siguiendo distintas configuraciones espaciales. Los resultados indican que la configuración y la disposición geométrica de los CFRP repercuten

  12. Evaluation of low-cost aluminum composites for aircraft engine structural applications

    Science.gov (United States)

    Mcdanels, D. L.; Signorelli, R. A.

    1983-01-01

    Panels of discontinuous SiC composites, with several aluminum matrices, were fabricated and evaluated. Modulus, yield strength and tensile strength results indicated that the properties of composites containing SiC whisker, nodule or particulate reinforcements were similar. The modulus of the composites was controlled by the volume percentage of the SiC reinforcement content, while the strength and ductility were controlled by both the reinforcement content and the matrix alloy. The feasibility of fabricating structural shapes by both wire performs and direct casting was demonstrated for Al2O3/Al composites. The feasibility of fabricating high performance composites into structural shapes by low pressure hot molding was demonstrated for B4C-coated B/Al composites.

  13. The life times of polymer composites in construction

    Science.gov (United States)

    Meier, Urs

    2016-05-01

    This paper discusses examples that prove the long-term reliability of Fiber Reinforced Polymers (FRP) under extreme loading conditions and outdoor weathering. Results of polymer/steel-composite anchorage systems, Glass Fiber Reinforced Polymer (GFRP) plates and shells, GFRP box girders, Carbon Fiber Reinforced Polymer (CFRP) post-tensioning tendons and CFRP stays are going to be presented.

  14. A domain-specific design architecture for composite material design and aircraft part redesign

    Science.gov (United States)

    Punch, W. F., III; Keller, K. J.; Bond, W.; Sticklen, J.

    1992-01-01

    Advanced composites have been targeted as a 'leapfrog' technology that would provide a unique global competitive position for U.S. industry. Composites are unique in the requirements for an integrated approach to designing, manufacturing, and marketing of products developed utilizing the new materials of construction. Numerous studies extending across the entire economic spectrum of the United States from aerospace to military to durable goods have identified composites as a 'key' technology. In general there have been two approaches to composite construction: build models of a given composite materials, then determine characteristics of the material via numerical simulation and empirical testing; and experience-directed construction of fabrication plans for building composites with given properties. The first route sets a goal to capture basic understanding of a device (the composite) by use of a rigorous mathematical model; the second attempts to capture the expertise about the process of fabricating a composite (to date) at a surface level typically expressed in a rule based system. From an AI perspective, these two research lines are attacking distinctly different problems, and both tracks have current limitations. The mathematical modeling approach has yielded a wealth of data but a large number of simplifying assumptions are needed to make numerical simulation tractable. Likewise, although surface level expertise about how to build a particular composite may yield important results, recent trends in the KBS area are towards augmenting surface level problem solving with deeper level knowledge. Many of the relative advantages of composites, e.g., the strength:weight ratio, is most prominent when the entire component is designed as a unitary piece. The bottleneck in undertaking such unitary design lies in the difficulty of the re-design task. Designing the fabrication protocols for a complex-shaped, thick section composite are currently very difficult. It is in

  15. A model study of the size and composition distribution of aerosols in an aircraft exhaust

    Energy Technology Data Exchange (ETDEWEB)

    Sorokin, A.A. [SRC `ECOLEN`, Moscow (Russian Federation)

    1997-12-31

    A two-dimensional, axisymmetric flow field model which includes water and sulphate aerosol formation represented by moments of the size and composition distribution function is used to calculate the effect of radial turbulent jet mixing on the aerosol size distribution and mean modal composition. (author) 6 refs.

  16. TECHNICAL NOTE: Low-cost delamination monitoring of CFRP beams using electrical resistance changes with neural networks

    Science.gov (United States)

    Todoroki, Akira; Ueda, Masahito

    2006-08-01

    Delamination is a significant defect of laminated composites. The present study employs an electrical resistance change method in an attempt to identify internal delaminations experimentally. The method adopts reinforcing carbon fibers as sensors. In our previous paper, an actual delamination crack in a carbon fiber reinforced plastic (CFRP) laminate was experimentally identified with artificial neural networks (ANNs) or response surfaces created from a large number of experiments. The experimental results were used for the learning of the ANN or for regressions of the response surfaces. For the actual application of the method, it is necessary to minimize the number of experiments in order to keep the cost of the experiments to a minimum. In the present study, therefore, finite-element method (FEM) analyses are employed to make sets of data for the learning of the ANN. First, the electrical conductivity of the CFRP laminate is identified by means of the least estimation error method. After that, the results of the FEM analyses are used for the learning of the ANN. The method is applied to the actual delamination monitoring of CFRP beams. As a result, the method successfully monitored the delamination location and size using only ten experiments.

  17. Performances of super-long span prestressed cable-stayed bridge with CFRP cables and RPC girder

    Institute of Scientific and Technical Information of China (English)

    Fang Zhi; Fan Fenghong; Ren Liang

    2013-01-01

    To discuss the applicability of advanced composite carbon fiber reinforced polymer (CFRP) and ultra-high performance concrete reactive powder concrete (RPC) in super-long span cable-stayed bridges , taking a 1 008 m cable-stayed bridge with steel girders and steel cables as an example,a new cable-stayed bridge in the same span with RPC girders and CFRP cables was designed,in which the cable’s cross section was determined by the principle of equivalent cable capacity and the girder’s cross section was determined in virtual of its stiffness, shear capacity and local stability. Based on the methods of finite element analysis,the comparative analysis of these two cable-stayed bridge schemes about static performances,dynamic performances,stability and wind resis-tance behavior were carried out. The results showed that it was feasible to form a highly efficient,durable concrete cable-stayed bridge with RPC girders and CFRP cables and made its applicable span range expand to 1 000 m long around.

  18. Acoustic Emission Monitoring of Compression-after-Impact Test of Nano-Particles-Coated CFRP Damaged by Simulated Lightning Strikes

    International Nuclear Information System (INIS)

    Nanoparticles-coated and impact-damaged carbon-fiber reinforced plastics(CFRP) laminates were tested under compression-after-impact(CAI) mode and the propagation of damage due to compressive loading has been monitored by acoustic emission(AE). The impact damage was induced not by mechanical loading but by a simulated lightning strike. CFRP laminates were made of carbon prepregs prepared by coating of conductive nano-particles directly on the fibers and the coupons were subjected to simulated lightning strikes with a high voltage/current impulse of 10∼40 kA within a few microseconds. The effects of nano-particles coating and the degree of damage induced by the simulated lightning strikes on the AE activities were examined, and the relationship between the compressive residual strength and AE behavior has been evaluated in terms of AE event counts and the onset of AE activity with the compressive loading. The degree of impact damage was also measured in terns of damage area by using ultrasonic C-scan images. From the results assessed during the CAI tests of damaged CFRP showed that AE monitoring appeared to be very useful to differentiate the degree of damage hence the mechanical integrity of composite structures damaged by lightning strikes

  19. Impact Testing and Analysis of Composites for Aircraft Engine Fan Cases

    Science.gov (United States)

    Roberts, Gary D.; Revilock, Duane M.; Binienda, Wieslaw K.; Nie, Walter Z.; Mackenzie, S. Ben; Todd, Kevin B.

    2002-01-01

    The fan case in a jet engine is a heavy structure because of its size and because of the requirement that it contain a blade released during engine operation. Composite materials offer the potential for reducing the weight of the case. Efficient design, test, and analysis methods are needed to efficiently evaluate the large number of potential composite materials and design concepts. The type of damage expected in a composite case under blade-out conditions was evaluated using a subscale test in which a glass/epoxy composite half-ring target was impacted with a wedge-shaped titanium projectile. Fiber shearing occurred near points of contact between the projectile and target. Delamination and tearing occurred on a larger scale. These damage modes were reproduced in a simpler test in which flat glass/epoxy composites were impacted with a blunt cylindrical projectile. A surface layer of ceramic eliminated fiber shear fracture but did not reduce delamination. Tests on 3D woven carbon/epoxy composites indicated that transverse reinforcement is effective in reducing delamination. A 91 cm (36 in.) diameter full-ring sub-component was proposed for larger scale testing of these and other composite concepts. Explicit, transient, finite element analyses indicated that a full-ring test is needed to simulate complete impact dynamics, but simpler tests using smaller ring sections are adequate when evaluation of initial impact damage is the primary concern.

  20. Bonded repair of composite aircraft structures: A review of scientific challenges and opportunities

    Science.gov (United States)

    Katnam, K. B.; Da Silva, L. F. M.; Young, T. M.

    2013-08-01

    Advanced composite materials have gained popularity in high-performance structural designs such as aerospace applications that require lightweight components with superior mechanical properties in order to perform in demanding service conditions as well as provide energy efficiency. However, one of the major challenges that the aerospace industry faces with advanced composites - because of their inherent complex damage behaviour - is structural repair. Composite materials are primarily damaged by mechanical loads and/or environmental conditions. If material damage is not extensive, structural repair is the only feasible solution as replacing the entire component is not cost-effective in many cases. Bonded composite repairs (e.g. scarf patches) are generally preferred as they provide enhanced stress transfer mechanisms, joint efficiencies and aerodynamic performance. With an increased usage of advanced composites in primary and secondary aerospace structural components, it is thus essential to have robust, reliable and repeatable structural bonded repair procedures to restore damaged composite components. But structural bonded repairs, especially with primary structures, pose several scientific challenges with the current existing repair technologies. In this regard, the area of structural bonded repair of composites is broadly reviewed - starting from damage assessment to automation - to identify current scientific challenges and future opportunities.

  1. New Proposal for Flexural Strengthening of Reinforced Concrete Beams Using CFRP T-Shaped Profiles

    Directory of Open Access Journals (Sweden)

    Renata Kotynia

    2015-11-01

    Full Text Available The purpose of this study was to evaluate the performance of a novel strengthening system using T-shaped carbon fiber reinforced polymer (CFRP profiles. The proposed system successfully combines the advantages of two established strengthening techniques, namely the near surface mounted (NSM and externally bonded (EB methods. The paper presents the experimental results of structural tests carried out on seven flexurally-strengthened and two non-strengthened full-scale reinforced concrete (RC members. Two T-shaped profiles having heights of 15 and 30 mm were applied. The main parameters of concrete strength and composite strengthening ratio were investigated to evaluate the efficiency of the proposed flexural strengthening system. All specimens were tested under a quasi-static six-point bending configuration. The test results showed a significant increase in the load bearing capacity and the stiffness of the RC beams with strengthening and also a notable reduction in maximum deflections. The high tensile strength utilization of the CFRP profiles places this strengthening technique as a promising alternative to other, less structurally-efficient systems.

  2. The Cutting Process, Chips and Cutting Forces in Machining CFRP

    DEFF Research Database (Denmark)

    Koplev, A.; Lystrup, Aage; Vorm, T.

    1983-01-01

    The cutting of unidirectional CFRP, perpendicular as well as parallel to the fibre orientation, is examined. Shaping experiments, ‘quick-stop’ experiments, and a new chip preparation technique are used for the investigation. The formation of the chips, and the quality of the machined surface...

  3. Development of Mechanical Anchor for CFRP Tendons Using Integrated Sleeve

    DEFF Research Database (Denmark)

    Schmidt, Jacob Wittrup; Bennitz, Anders; Täljsten, Björn;

    2010-01-01

    A durable and very efficient external strengthening system is achieved if steel tendons for post-tensioning applications can be replaced with CFRP (Carbon Fibre Reinforced Polymer) tendons and if reliable anchorage systems are developed,. This paper presents a newly developed and simple-to-use two...

  4. RC T-Beams Externally Prestressed with Unbonded CFRP

    DEFF Research Database (Denmark)

    Schmidt, Jacob Wittrup; Bennitz, Anders; Nilimaa, Jonny;

    2010-01-01

    An experimental test series with seven beams externally prestressed with unbonded CFRP 7 (Carbon Fibre Reinforced Polymer) tendons has been performed. Presence of deviator, initial 8 tendon depth and prestressing force are varied. Results and behaviors are compared to 9 common beam theory, matching...

  5. FEA Based Analysis of Composite Torque Link for a Passenger Aircraft Landing Gear

    OpenAIRE

    R. Arravind; R. Mohamed Rijuvan

    2013-01-01

    In the implementation of a composite landing gear technology program was started, a composite torque link for transport airplane landing gear applications was developed. The torque link was designed by finite element analysis and analysis for maximum stress condition. The torque link was fabricated by Resin Transfer Moulding (RTM) for which a tooling concept was developed. Static tests demonstrated the load carrying capabilities in undamaged and damaged condition of the torque link since all ...

  6. Development of a continuous manufacturing method for a CFRP collapsible tube mast

    Science.gov (United States)

    Bowen, D. H.; Davidson, R.; Lee, R. J.; Thorpe, T.

    1986-06-01

    A sequential molding process was developed for forming continuous lengths of profiled carbon fiber reinforced plastic (CFRP) sheet, and for the edge-bonding of two identical profiles to produce a lenticular-shaped collapsible tube mast (CTM). The process was designed to enable a wide range of CTM sizes, characterized by the shape radius r, to be produced, and it will accept either thermosetting or thermoplastic matrix composites. The Tube Manufacturing Method (TMM) was proved by the construction of a laboratory scale rig and its use to produce continuously 10 m lengths of mast profile of uniform section and surface finish. The mechanical properties of the fabrics impregnated with the two resins were measured to provide basic tube mast design data. Viscoelastic relaxations in both types of composites were determined after storing sections of mast profile in the flattened condition over periods of time as a function of temperature.

  7. Experimental study and analysis on fatigue stiffness of RC beams strengthened with CFRP and steel plate

    Institute of Scientific and Technical Information of China (English)

    LU Yi-yan; HU Ling; LI Shan; WANG Kang-hao

    2016-01-01

    The objective of this work is to investigate the fatigue behavior of reinforced concrete (RC) beams strengthened with externally bonded carbon fiber reinforced polymer (CFRP) and steel plate. An experimental investigation and theoretical analysis were made on the law of deflection development and stiffness degradation, as well as the influence of fatigue load ranges. Test results indicate that the law of three-stage change under fatigue loading is followed by both midspan deflection and permanent deflection, which also have positive correlation with fatigue load amplitude. Fatigue stiffness of composite strengthened beams degrades gradually with the increasing of number of cycles. Based on the experimental results, a theoretical model by effective moment of inertia method is developed for calculating the sectional stiffness of such composite strengthened beams under fatigue loading, and the calculated results are in good agreement with the experimental results.

  8. Assessment of Multiple Delamination in Laminated Composites for Aircrafts using X-ray Backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Noh Yu [College of Medicine, Hanyang University, Cheonan (Korea, Republic of)

    2010-02-15

    A Compton X-ray backscatter technique has been developed to quantitatively assess impact damage in quasi-isotropic laminated composites made by a drop-weight tester. X-ray backscatter imaging system with a slit-type camera is constructed to obtain a cross-sectional profile of impact-damaged laminated composites from the electron-density variation of the cross section. A nonlinear scattering model based on Boltsman equation is introduced to compute Compton X-ray backscattering field for the defect assessment. An adaptive filter is also used to reduce noises from many sources including quantum noise and irregular distributions of fibers and matrix in composites. Delaminations masked or distorted by the first delamination are detected and characterized effectively by the Compton X-ray backscatter technique, both in width and location, by application of error minimization algorithm

  9. FEA Based Analysis of Composite Torque Link for a Passenger Aircraft Landing Gear

    Directory of Open Access Journals (Sweden)

    R. Arravind

    2013-08-01

    Full Text Available In the implementation of a composite landing gear technology program was started, a composite torque link for transport airplane landing gear applications was developed. The torque link was designed by finite element analysis and analysis for maximum stress condition. The torque link was fabricated by Resin Transfer Moulding (RTM for which a tooling concept was developed. Static tests demonstrated the load carrying capabilities in undamaged and damaged condition of the torque link since all specimens failed beyond their Design Ultimate Load level for that case we are hereby carryout the analysis process in order to find the ultimate load and yield stress for the torque link.

  10. Instrumentation on commercial aircraft for monitoring the atmospheric composition on a global scale: the IAGOS system, technical overview of ozone and carbon monoxide measurements

    Directory of Open Access Journals (Sweden)

    Phillipe Nédélec

    2015-06-01

    Full Text Available This article presents the In-service Aircraft of a Global Observing System (IAGOS developed for operations on commercial long-range Airbus aircraft (A330/A340 for monitoring the atmospheric composition. IAGOS is the continuation of the former Measurement of OZone and water vapour on Airbus In-service airCraft (MOZAIC programme (1994–2014 with five aircraft operated by European airlines over 20 yr. MOZAIC has provided unique scientific database used worldwide by the scientific community. In continuation of MOZAIC, IAGOS aims to equip a fleet up to 20 aircraft around the world and for operations over decades. IAGOS started in July 2011 with the first instruments installed aboard a Lufthansa A340-300, and a total of six aircraft are already in operation. We present the technical aircraft system concept, with basic instruments for O3, CO, water vapour and clouds; and optional instruments for measuring either NOy, NOx, aerosols or CO2/CH4. In this article, we focus on the O3 and CO instrumentation while other measurements are or will be described in specific papers. O3 and CO are measured by optimised but well-known methods such as UV absorption and IR correlation, respectively. We describe the data processing/validation and the data quality control for O3 and CO. Using the first two overlapping years of MOZAIC/IAGOS, we conclude that IAGOS can be considered as the continuation of MOZAIC with the same data quality of O3 and CO measurements.

  11. Novel Epoxy Particulate Composites for Mitigation of Insect Residue Adhesion on Future Aircraft Surfaces

    Science.gov (United States)

    Wohl, Christopher J.; Smith, Joseph G., Jr.; Gardner, John M.; Penner, Ronald K.; Connell, John W.; Siochi, Emilie J.

    2014-01-01

    Drag is reduced significantly for airflow over surfaces when laminar flow can be maintained over greater chord lengths, the distance from the leading edge of an airfoil.1 However, surface imperfections, such as chipped paint, scratches, and events that change topography on a microscopic scale can introduce airflow instabilities resulting in premature transition to turbulent flow.1 Although many of these surface imperfections can be avoided with proper maintenance, advanced materials, and advanced manufacturing practices, topographical surface anomalies arising during flight from insect impacts cannot be controlled and can influence laminar flow stability. Practical solutions to this operational challenge need to be developed for future aircraft to have full advantage of laminar flow designs that improve fuel efficiency.2 Researchers have investigated various methods to mitigate insect residue adhesion for decades.3 Although several techniques have demonstrated efficacy including mechanical scrapers, active liquid discharge systems, and sacrificial paper coatings, they have not been commercially implemented due to increased manufacturing and operational complexity, environmental impact, and weight penalties. Coatings offer a simple route for passive insect residue adhesion prevention without many of the challenges associated with maintenance of laminar flow.4 In our previous work, we determined that most commercially available materials were not effective at insect residue adhesion.5 We also identified improvements when both surface energy could be controlled by surface modifying agents and the topography could be altered through the use of micron-sized and nanometer-sized filler materials.6 In this work, these general principles were applied to an epoxy system to evaluate the behavior of the surface modifying agent, a fluorinated alkyl ether oligomer, on surface energy and insect residue adhesion properties.

  12. High Temperature Lightweight Self-Healing Ceramic Composites for Aircraft Engine Applications

    Science.gov (United States)

    Raj, Sai V.; Singh, Mrityunjay; Bhatt, Ramakrishna T.

    2014-01-01

    The present research effort was undertaken to develop a new generation of SiC fiber- reinforced engineered matrix composites (EMCs) with sufficient high temperature plasticity to reduce crack propagation and self-healing capabilities to fill surface-connected cracks to prevent the oxygen ingress to the fibers. A matrix engineered with these capabilities is expected to increase the load bearing capabilities of SiCSiC CMCs at high temperatures. Several matrix compositions were designed to match the coefficient of thermal expansion (CTE) of the SiC fibers using a rule of mixture (ROM) approach. The CTE values of these matrices were determined and it was demonstrated that they were generally in good agreement with that of monolithic SiC between room temperature and 1525 K. The parameters to hot press the powders were optimized, and specimens were fabricated for determining bend strength, CTE, oxidation and microstructural characteristics of the engineered matrices. The oxidation tests revealed that some of the matrices exhibited catastrophic oxidation, and therefore, these were eliminated from further consideration. Two promising compositions were down selected based on these results for further development. Four-point bend tests were conducted on these two promising matrices between room temperature and 1698 K. Although theses matrices were brittle and failed at low stresses at room temperature, they exhibited high temperature ductility and higher stresses at the higher temperatures. The effects of different additives on the self-healing capabilities of these matrices were investigated. The results of preliminary studies conducted to slurry and melt infiltration trials with CrSi2 are described.

  13. Elastomer toughened polyimide adhesives. [bonding metal and composite material structures for aircraft and spacecraft

    Science.gov (United States)

    St.clair, A. K.; St.clair, T. L. (Inventor)

    1985-01-01

    A rubber-toughened, addition-type polyimide composition is disclosed which has excellent high temperature bonding characteristics in the fully cured state and improved peel strength and adhesive fracture resistance physical property characteristics. The process for making the improved adhesive involves preparing the rubber-containing amic acid prepolymer by chemically reacting an amine-terminated elastomer and an aromatic diamine with an aromatic dianhydride with which a reactive chain stopper anhydride has been mixed, and utilizing solvent or mixture of solvents for the reaction.

  14. Multilevel probabilistic approach to evaluate manufacturing defect in composite aircraft structures

    Energy Technology Data Exchange (ETDEWEB)

    Caracciolo, Paola, E-mail: paola.caracciolo@airbus.com [AIRBUS INDUSTRIES Germany, Department of Airframe Architecture and Integration-Research and Technology-Kreetslag, 10, D-21129, Hamburg (Germany)

    2014-05-15

    In this work it is developed a reliable approach and its feasibility to the design and analysis of a composite structures. The metric is compared the robustness and reliability designs versus the traditional design, to demonstrate the gain that can be achieved with a probabilistic approach. The use of the stochastic approach of the uncertain parameteters in combination with the multi-scale levels analysis is the main objective of this paper. The work is dedicated to analyze the uncertainties in the design, tests, manufacturing process, and key gates such as materials characteristic.

  15. Multilevel probabilistic approach to evaluate manufacturing defect in composite aircraft structures

    Science.gov (United States)

    Caracciolo, Paola

    2014-05-01

    In this work it is developed a reliable approach and its feasibility to the design and analysis of a composite structures. The metric is compared the robustness and reliability designs versus the traditional design, to demonstrate the gain that can be achieved with a probabilistic approach. The use of the stochastic approach of the uncertain parameteters in combination with the multi-scale levels analysis is the main objective of this paper. The work is dedicated to analyze the uncertainties in the design, tests, manufacturing process, and key gates such as materials characteristic.

  16. Interaction between Crosswind and Aviation-Fuel Fire Engulfing a Full-Scale Composite-Type Aircraft: A Numerical Study

    Directory of Open Access Journals (Sweden)

    Hui Ying Wang

    2015-05-01

    Full Text Available This numerical study focuses on the fire phenomenology associated with the presence of a composite-type aircraft immersed, at one particular location and orientation, within a large aviation-fuel fire in a moving fluid medium. An extension of the eddy dissipation concept is incorporated, allowing one to investigate the roles of the wind speed and its direction on the fire growth, heat flux distribution and smoke products, such as carbon monoxide and soot. The predicted flame shape compares well with the measurements for an intermediate-scale fire. The outcome of the study is interesting, and the interaction model between turbulence and combustion is indeed adequate. The prediction indicates that interaction between the large object and fire environment combined with the influence of wind conditions dramatically affects the continuous flame shape. The increase of the wind speed results in an alteration of the distribution of the incident heat fluxes to the engulfed fuselage skin for a case where the fire and fuselage are of comparable size. The highest heat flux occurs on the windward side of the fuselage for the low and medium winds, but on the leeward side of the fuselage for the high wind. The peak in heat flux to the medium or high wind is almost equal in magnitude, but about a factor four increase of that to the low wind.

  17. Reliability-based aeroelastic optimization of a composite aircraft wing via fluid-structure interaction of high fidelity solvers

    International Nuclear Information System (INIS)

    We consider reliability based aeroelastic optimization of a AGARD 445.6 composite aircraft wing with stochastic parameters. Both commercial engineering software and an in-house reliability analysis code are employed in this high-fidelity computational framework. Finite volume based flow solver Fluent is used to solve 3D Euler equations, while Gambit is the fluid domain mesh generator and Catia-V5-R16 is used as a parametric 3D solid modeler. Abaqus, a structural finite element solver, is used to compute the structural response of the aeroelastic system. Mesh based parallel code coupling interface MPCCI-3.0.6 is used to exchange the pressure and displacement information between Fluent and Abaqus to perform a loosely coupled fluid-structure interaction by employing a staggered algorithm. To compute the probability of failure for the probabilistic constraints, one of the well known MPP (Most Probable Point) based reliability analysis methods, FORM (First Order Reliability Method) is implemented in Matlab. This in-house developed Matlab code is embedded in the multidisciplinary optimization workflow which is driven by Modefrontier. Modefrontier 4.1, is used for its gradient based optimization algorithm called NBI-NLPQLP which is based on sequential quadratic programming method. A pareto optimal solution for the stochastic aeroelastic optimization is obtained for a specified reliability index and results are compared with the results of deterministic aeroelastic optimization.

  18. Design and Optimization of a Composite Canard Control Surface of an Advanced Fighter Aircraft under Static Loading

    Directory of Open Access Journals (Sweden)

    Shrivastava Sachin

    2015-01-01

    Full Text Available The minimization of weight and maximization of payload is an ever challenging design procedure for air vehicles. The present study has been carried out with an objective to redesign control surface of an advanced all-metallic fighter aircraft. In this study, the structure made up of high strength aluminum, titanium and ferrous alloys has been attempted to replace by carbon fiber composite (CFC skin, ribs and stiffeners. This study presents an approach towards development of a methodology for optimization of first-ply failure index (FI in unidirectional fibrous laminates using Genetic-Algorithms (GA under quasi-static loading. The GAs, by the application of its operators like reproduction, cross-over, mutation and elitist strategy, optimize the ply-orientations in laminates so as to have minimum FI of Tsai-Wu first-ply failure criterion. The GA optimization procedure has been implemented in MATLAB and interfaced with commercial software ABAQUS using python scripting. FI calculations have been carried out in ABAQUS with user material subroutine (UMAT. The GA's application gave reasonably well-optimized ply-orientations combination at a faster convergence rate. However, the final optimized sequence of ply-orientations is obtained by tweaking the sequences given by GA's based on industrial practices and experience, whenever needed. The present study of conversion of an all metallic structure to partial CFC structure has led to 12% of weight reduction. Therefore, the approach proposed here motivates designer to use CFC with a confidence.

  19. Effect of CFRP strengthening on the response of RC slabs to hard projectile impact

    Energy Technology Data Exchange (ETDEWEB)

    Almusallam, Tarek; Al-Salloum, Yousef; Alsayed, Saleh; Iqbal, Rizwan; Abbas, Husain, E-mail: abbas_husain@hotmail.com

    2015-05-15

    Highlights: • Studied response of CFRP-strengthened RC slabs under the impact load. • Slabs were tested under the strike of hemispherical steel projectiles at varying impact. • The slabs were analyzed numerically using LS-DYNA. • Strengthening increased the ballistic limit velocity by 18% and perforation energy by 56.7%. • CFRP sheet reduced the crater damage and contained the flying concrete fragments. - Abstract: In this paper impact response of CFRP-strengthened RC panels under the impact of non-deformable projectiles has been presented. The control and CFRP-strengthened RC slab panels were tested under the strike of hemispherical nosed steel projectiles at varying impact velocities. The response of these panels was investigated experimentally as well as numerically. The damage of the slab panels was measured in terms of the penetration depth, formation of cracks, spalling and scabbing areas and fracture of CFRP sheet. This study presents a practical and efficient numerical method for analyzing the impact response of CFRP-strengthened RC structures using LS-DYNA. The CFRP strengthening was found to increase the ballistic limit velocity by 18%, perforation energy of RC slabs by 56.7%, reduce the front crater damage and contains the flying of concrete fragments from the rear face. The maximum impact force occurs at almost same penetration depth for the control and CFRP-strengthened slabs but the restraint provided by CFRP increased the penetration depth by about 1/19.3 of the thickness of slab.

  20. Novel approaches for alleviation of electrical hazards of graphite-fiber composites. [aircraft safety

    Science.gov (United States)

    Ramohalli, K.

    1979-01-01

    Four basically different approaches were considered: gasification of fibers, retention in the matrix, clumping to prevent entrainment, and electrical insulation of fibers. The techniques used to achieve them are described in some detail. These involved surface treatment of fibers to improve the wettability of fibers and coating the fibers with the selected substances before laying them up for composite fabrication. Thermogravimetric analyses were performed on the plain and treated fibers in inert (nitrogen, argon) and reactive (air) atmospheres. The treated fibers embedded in epoxy were ignited in a Bunsen flame to determine the efficiency of these treatments. A simple apparatus was assembled to detect the time for the first short circuit (in a typical electrical circuit) when exposed to the combustion products from a graphite fiber composite fire. The state-of-the-art and treated fibers cast in typical epoxy were burned and ranked for potential success. It was inferred that the gasification schemes appear promising when reduction or oxidation is tried. It was also found that some very promising candidates were available for the clumping and for the electrical insulation of fibers.

  1. Development and test verification of the Ariane 4 interstage 2/3 in CFRP

    Science.gov (United States)

    Blaas, C.; Wiggenraad, J. F. M.

    The interstage 2/3 configuration of the Ariane 4 launcher has been redesigned, using the CFRP composite (instead of aluminum) for the curved blade-stiffened panels, in order to reduce weight. Verification analysis of the design was performed using NASTRAN and BOSOR4 models. In experimental tests, flat stiffened panels were tested in compression to verify the selected design details of the cylinder. Three different sizes of subcomponent panels were tested with the objectives of determining the local buckling behavior at room temperature and at 180 C, assessing the strength of the panel to end-ring connections, and establishing the global panel buckling behavior between ring frames. As a result of the tests, the stiffener run-out configuration was modified to prevent premature separation at the tip.

  2. Experimental and numerical analysis of defects in composite panels used in business aircrafts interior

    Science.gov (United States)

    Ruiz, Edu; Courteau-Godmaire, H.; Fotsing, R.; Billotte, C.; Levesque, M.

    2016-05-01

    This paper provides an optical characterization and numerical prediction of local deformations appearing on the visible side of composite sandwich panels used for interior furniture of business airplanes. During manufacturing of furniture panels, metallic inserts are bonded inside the sandwich panel using an epoxy adhesive. Surface defects appear on the visible side of the panels due to curing of the adhesive, but also because of temperature gradients and humidity during manufacturing and in service. This paper presents an optical characterization based on deflectometry principle, that allows qualitative and quantitative analyses of the surface deformations in 3-dimensions. In addition, this paper presents a parametric model based on finite elements to predict the formation of surface defects using ABAQUS. A comparison is presented between the experimental observations and numerical predictions with good agreement between them.

  3. RC Columns Strengthened with Novel CFRP Systems: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Annalisa Napoli

    2015-10-01

    Full Text Available This paper presents an experimental study undertaken to investigate the seismic behavior of full scale square (300 mm × 300 mm reinforced concrete (RC columns strengthened with novel systems employing carbon fiber-reinforced polymers (CFRP wraps. Experimental tests were carried out by subjecting specimens to a constant axial load and a cyclically reversed horizontal force applied in displacement control. Results have allowed for investigating the influence of the used strengthening systems on the specimens’ performance in terms of flexural strength and ductility as well as on the exhibited failure modes. The effectiveness of the studied techniques is also evaluated by comparing the performance of tested specimens with that of companion columns strengthened with alternative CFRP systems investigated in a previous experimental campaign.

  4. Experimental Study on CFRP Strengthened Cold Formed Channel Columns

    Directory of Open Access Journals (Sweden)

    Sreedhar Kalavagunta

    2013-09-01

    Full Text Available Cold-formed steel members usually display local-global buckling interaction which strongly effects the structural strength of columns. Through strengthening web of the members this buckling can be controlled to some extent. In this investigation, Carbon Fibre Reinforced Polymers (CFRP is used for strengthening cold formed steel channel member. This paper presents compression tests of cold-formed plain and CFRP strengthened steel channel section columns. This paper also proposes a design method based on Direct Strength Method provisions specified in American Iron and Steel Institute (AISI, for determining the axial compression strength. Results obtained from the proposed design method are compared with experimental test data and are found to be in good agreement.

  5. Repair and Strengthening of Reinforced Concrete Structures Using CFRP Plates

    International Nuclear Information System (INIS)

    The infrastructure's increasing decay is frequently combined with the need for upgrading so that structures can meet more stringent design requirements (e.g., increased traffic volumes in bridges exceeding the initial design loads), and hence the aspect of civil engineering infrastructure renewal has received considerable attention over the past few years throughout the world. At the same time, seismic retrofit has become equally important, especially in the areas of high seismic risk. The worldwide acceptance of external plate bonding using CFRP laminates for the repair of under strengthened or damaged reinforced concrete beams is the real incentive for many investigators to devote a great deal of effort to physically understand the response of such beams under externally applied loads. This paper is aimed towards providing a review of the repair and strengthening of the RC concrete structures using CFRP plates along with introducing the basics of the above mentioned technique

  6. Evaluation of electrical transverse conductivity of the unidirectional CFRP

    Science.gov (United States)

    Khebbab, Mohamed; Feliachi, Mouloud; El Hadi Latreche, M.

    2016-01-01

    In this paper, a technique for the calculation of the electrical transverse conductivity of unidirectional carbon fiber reinforced polymer (CFRP), based on Markov chains, is proposed. Inspired by the microscopic cross-sectional structure of CFRP, an electrical percolation system is constructed. The effective transverse conductivity is derived from an equivalent conductance of the percolation network. To achieve such a determination, a notion of escape probability associated to absorbing Markov chains is applied. The obtained results are compared with those given by percolation theory; and also with published experimental data. Our results are shown to be in good agreement with the references. Contribution to the topical issue "Numelec 2015 - Elected submissions", edited by Adel Razek

  7. EXPERIMENTAL FIRE BEHAVIOUR OF PRECAST CFRP PRETENSIONED HPSCC SLABS

    OpenAIRE

    Maluk, Cristian; Giovanni P. Terrasi; Bisby, Luke; Stutz, Alex; Hugi, Erich

    2014-01-01

    Optimized concrete elements have been developed using high-performance, self- consolidating, fibre-reinforced concrete (HPSCC) reinforced with high-strength, lightweight, non-corroding pre-stressed carbon fibre reinforced plastic tendons. This new type of thin-walled precast carbon FRP (CFRP) pretensioned HPSCC slab has been used in building façades and is under consideration for a range of other applications in buildings. However, it is well known that the bond strength between both steel an...

  8. Stress-strain model for partial CFRP confined concrete

    OpenAIRE

    Ferreira, Débora R. S. M.; Barros, Joaquim A. O.

    2008-01-01

    Concrete columns requiring strengthening intervention always contain a certain percentage of steel hoops. Applying strips of wet lay-up carbon fiber reinforced polymer (CFRP) sheets in-between the existent steel hoops might, therefore, be an appropriate confinement technique with both technical and economic advantages, when full wrapping of a concrete column is taken as a basis of comparison. To assess the effectiveness of the partial wrapping technique, circular cross section con...

  9. Strengthening of old metallic structures in fatigue with CFRP materials

    DEFF Research Database (Denmark)

    Hansen, Christian Skodborg; Schmidt, Jacob Wittrup; Täljsten, Björn

    2007-01-01

    Research regarding strengthening of old metallic structures using unidirectional carbon fibre reinforced polymer(CFRP) laminates has shown very usable to lengthen the service life of structural members in tension With the basis in a 110 year old riveted beam, centre notched test specimens have been...... to a direct linear elastic theory and compared with measured results. The experiments showed a good match between theory and measurements....

  10. Damage monitoring of CFRP retrofit using optical fiber sensors

    Science.gov (United States)

    Joshi, Kunal; Breaux Frketic, Jolie; Olawale, David; Dickens, Tarik

    2015-04-01

    With nearly 25% of bridge infrastructure deemed deficient, repair of concrete structures is a critical need. FRP materials as thin laminates or fabrics are appearing to be an ideal alternative to traditional repair technology, because of their high strength to weight ratios and stiffness to weight ratios. In addition, FRP materials offer significant potential for lightweight, high strength, cost-effective and durable retrofit. One drawback of using CFRP retrofitting is its brittle-type failure; caused by its nearly linear elastic nature of the stress-strain behavior. This causes a strength reduction of the retrofitted member, thus the health of the retrofit applied on the structure becomes equally important to sustain the serviceability of the structure. This paper provides a system to monitor damage on the CFRP retrofits through optical fiber sensors which are woven into the structure to provide damage sensing. Precracked reinforced concrete beams were retrofitted using CFRP laminates with the most commonly used FRP application technique. The beams were tested under constant stress to allow the retrofitting to fail while evaluating the performance of the sensing system. Debonding failure modes at a stress of 9 MPa were successfully detected by TL optical fiber sensors in addition to detection during flexural failure. Real-time failure detection of FRP strengthened beams was successfully achieved and the retrofit damage-monitoring scheme aims at providing a tool to reduce the response time and decision making involved in maintenance of deficient structures.

  11. Delamination detection in CFRP laminates using FOD sensor

    Science.gov (United States)

    Li, Fucai; Kageyama, Kazuro; Murayama, Hideaki; Ohsawa, Isamu

    2009-07-01

    In this paper, carbon fiber reinforced plastic (CFRP) laminates (pristine and delaminated) are addressed for the purpose of damage assessment. Recently developed Doppler effect-based fiber optic (FOD) sensor was bonded on surface of each CFRP laminate to acquire piezoceramic-disc-excited guided waves propagating in the specimen. Characteristics of the captured guided wave signals were extracted by taking advantage of two well-developed signal processing algorithms, namely, linear-phase finite impulse response filter and Hilbert transform, so as to investigate the influence of the delaminations to the guided wave propagation. When guided waves are incident on discontinuities, mode conversion may occur as a result of satisfying the boundary conditions along the discontinuities. Both the dispersive characteristics of multi-mode guided waves and features of the guided-wave-generated fundamental shear horizontal (SH0) wave were applied for damage evaluation and multiple-damage detection. The results demonstrate that the FOD sensor is effective in multiple delamination detection for CFRP laminates because of its omnidirectional property in ultrasonic detection.

  12. Investigation on drilling-grinding of CFRP

    Institute of Scientific and Technical Information of China (English)

    Yanming QUAN; Wenwang ZHONG

    2009-01-01

    It is difficult to machine polymer matrix composites reinforced by carbon fibre, and the hole-making process is the most necessary machining process for composite plate products. Conventional drills have a very short life in the drilling of this kind of composites and the quality of the hole is very poor. In this paper, the cemented or plated diamond core tools are tested to make holes in carbon fibre/epoxy composite plates. The effects of machining parameters, cooling and chip removal on the tool life, and the hole quality are investigated. The results indicate that the material removal mechanism of the two kinds of diamond tools is not like the cutting effect of the conventional drilling but similar to that of grinding. Satisfactory effects in making holes in the composites are obtained--quite acceptable machined hole quality, low costs, and long wear-resistant endurance.

  13. Modelling Strategies for Predicting the Residual Strength of Impacted Composite Aircraft Fuselages

    Science.gov (United States)

    Lachaud, Frederic; Espinosa, Christine; Michel, Laurent; Rahme, Pierre; Piquet, Robert

    2015-12-01

    Aeronautic Certification rules established for the metallic materials are not convenient for the composite structures concerning the resistance against impact. The computer-based design is a new methodology that is thought about to replace the experimental tests. It becomes necessary for numerical methods to be robust and predictive for impact. Three questions are addressed in this study: (i) can a numerical model be "mechanically intrinsic" to predict damage after impact, (ii) can this model be the same for a lab sample and a large structure, and (iii) can the numerical model be predictive enough to predict the Compression After Impact (CAI)? Three different computational strategies are used and compared: a Cohesive Model (CM), a Continuous Damage Model (CDM) coupling failure modes and damage, and a Mixed Methodology (MM) using the CDM for delamination initiation and the CM for cracks propagation. The first attempts to use the Smooth Particle Hydrodynamics method are presented. Finally, impact on a fuselage is modelled and a numerical two-stage strategy is developed to predict the CAI.

  14. Evaluation of Ceramic Matrix Composite Technology for Aircraft Turbine Engine Applications

    Science.gov (United States)

    Halbig, Michael C.; Jaskowiak, Martha H.; Kiser, James D.; Zhu, Dongming

    2013-01-01

    The goals of the NASA Environmentally Responsible Aviation (ERA) Project are to reduce the NO(x) emissions, fuel burn, and noise from turbine engines. In order to help meet these goals, commercially-produced ceramic matrix composite (CMC) components and environmental barrier coatings (EBCs) are being evaluated as parts and panels. The components include a CMC combustor liner, a CMC high pressure turbine vane, and a CMC exhaust nozzle as well as advanced EBCs that are tailored to the operating conditions of the CMC combustor and vane. The CMC combustor (w/EBC) could provide 2700 F temperature capability with less component cooling requirements to allow for more efficient combustion and reductions in NOx emissions. The CMC vane (w/EBC) will also have temperature capability up to 2700 F and allow for reduced fuel burn. The CMC mixer nozzle will offer reduced weight and improved mixing efficiency to provide reduced fuel burn. The main objectives are to evaluate the manufacturability of the complex-shaped components and to evaluate their performance under simulated engine operating conditions. Progress in CMC component fabrication, evaluation, and testing is presented in which the goal is to advance from the proof of concept validation (TRL 3) to a system/subsystem or prototype demonstration in a relevant environment (TRL 6).

  15. On the plastic behaviour of multi directional epoxy-bolted CFRP laminates

    DEFF Research Database (Denmark)

    Jensen, Aage; Poulsen, Ervin

    2004-01-01

    The second generation of CFRP laminate has recently been developed. It is a multi directional CFRP laminate, i.e. a laminate with carbon fibres having several directions other than the first generation. The paper describes the laboratory tests carried out in order to develop anchorage devices...

  16. Simulation and detection of flaws in pre-cured CFRP using laser displacement sensing

    NARCIS (Netherlands)

    Miesen, N.; Sinke, J.; Groves, R.M.; Benedictus, R.

    2015-01-01

    The novelty of the research is the detection of different types of flaws in the prepreg carbon fibre-reinforced fibres (CFRP) layup compared to in cured products. This paper presents the development of a new method for in situ detection of prepreg CFRP production flaws combining laser displacement s

  17. The influence of temperature variations on ultrasonic guided waves in anisotropic CFRP plates.

    Science.gov (United States)

    Putkis, O; Dalton, R P; Croxford, A J

    2015-07-01

    Carbon Fibre Reinforced Polymer (CFRP) materials are lightweight and corrosion-resistant and therefore are increasingly used in aerospace, automotive and construction industries. In Structural Health Monitoring (SHM) applications of CFRP materials, ultrasonic guided waves potentially offer large area inspection or inspection from a remote location. This paper addresses the effect of temperature variation on guided wave propagation in highly anisotropic CFRP materials. Temperature variations cause changes in guided wave velocity that can in turn compromise the baseline subtraction procedures employed by many SHM systems for damage detection. A simple model that describes the dependence of elastic properties of the CFRP plates on temperature is presented in this paper. The model can be used to predict anisotropic velocity changes and baseline subtraction performance under varying thermal conditions. The results produced by the model for unidirectional and 0/90 CFRP plates are compared with experimental measurements. PMID:25812468

  18. Use of laser reflection technique for defect detection in CFRP-concrete systems

    Science.gov (United States)

    Qiu, Qiwen; Lau, Denvid

    2016-04-01

    This paper presents a new laser reflection technique which can identify the near-surface defects in concrete structures bonded with carbon fiber reinforced polymer (CFRP). In this study, a laser beam is used to illuminate the surface of CFRP-concrete panel, and the pattern of the laser reflection is recorded by a high resolution digital camera. Under the laser illumination, the surface of the tested object is heated and expanded. The surface expansion can be identified through observing the expanding reflection pattern. Based on our experimental observation, the defect region exhibits much greater expansion of laser reflection pattern than that in intact region. Results also indicate that both the defect area and the defect depth can influence the change of reflection pattern. In view of the measurement principle of the laser reflection technique, it is expected that the application can be further extended to the areas like CFRP-wood structures, CFRP-masonry structures and CFRP-steel structures.

  19. Finite element analysis of frame beams strengthened by CFRP in the structure%CFRP 加固结构中框架梁有限元分析

    Institute of Scientific and Technical Information of China (English)

    刘强; 乔文正; 高树峰

    2015-01-01

    In order to research the influence of performance on RC structure strengthened by CFRP,non-linear analysis is performed on RC frame beams by ANSYS. Research on the mechanical performance of RC frame beams with a rectangle cut is being performed before or after strengthe-ning. The result can be summarized as follows:the mechanical performance of RC frame beams strengthened by CFRP is greatly improved,and the function of the CFRP is used fully.%为了研究 CFRP(碳纤维复合材料)对于结构性能的影响,采用 ANSYS 有限元分析软件对加固工程中的 RC 框架梁进行了非线性分析,研究了 RC 矩形截面框架梁在 CFRP 加固前后的力学性能,研究结果表明:CFRP 加固后的框架梁的力学性能明显提高,CFRP 充分发挥了作用。

  20. Experimental Investigation on Contribution of CFRP Attachment to Durability of Reinforced Concrete Structure Subjected to Chloride Attack

    Institute of Scientific and Technical Information of China (English)

    Chen Fengshan; Zhao Guofan; Pan Deqiang

    2006-01-01

    The function of externally-bonded carbon fiber reinforced polymer (CFRP) in preventing chloride from entering into concrete is verified by experiment. The results show that externally-bonded CFRP can be considered as a part of corrosion prevention system of strengthened concrete structures subjected to chloride ingress, and the contribution of CFRP should be considered in evaluation of durability of reinforced concrete structures with externally-bonded CFRP. With the effective shielding function of CFRP considered, an equation for residual lifetime prediction of concrete structures with externally-bonded CFRP is derived from Ficks dispersion law. CFRP has two functions for coastal concrete structures, including strengthening and increasing durability as part of corrosion prevention system.

  1. 复合材料结构健康监测技术在飞机中的应用%Application of Structural Health Monitoring on Composite Aircraft

    Institute of Scientific and Technical Information of China (English)

    朱新宇; 卢俊文

    2011-01-01

    结构健康监测(SHM)实现了工程结构设计与使用上的技术性跨越.将SHM应用于复合材料中,使得智能结构的设计与制造成为了现实.文章重点阐述了飞机复合材料结构SHM技术所面临的技术问题.SHM使飞机复合材料结构得视情维修以及降低其使用周期内成本成为可能,可以促使复合材料结构设计与制造的优化,最后指出了为实现复合材料SHMS所需要重点研究的理论与技术.%Structural health monitoring (SHM) achieves technological leaps in the design and operation of engineering structures. Composite materials incorporating SHM systems enable the design and manufacture of tailored smart structures. This paper mainly focuses on their application to aircraft as a means of highlighting the issues that face SHM in composite structures. Incorporation of SHM has the potential to reduce through-life costs by the adoption of condition based maintenance and to reduce operating costs by the design of more structurally efficient aircraft. The paper addresses issues involved in the design, certification, manufacture and through life support of such structures. Critical areas of development have been identified to enable the implementation of SHM in future composite aircraft structures.

  2. Program for establishing long-time flight service performance of composite materials in the center wing structure of C-130 aircraft. Phase 3: Fabrication

    Science.gov (United States)

    Harvill, W. E.; Kays, A. O.

    1974-01-01

    The manufacturing plan for three C-130 aircraft center wing box test articles, selectively reinforced with boron-epoxy composites, is outlined for the following tasks: (1) tooling; (2) metal parts fabrication: (3) reinforcing laminate fabrication; (4) laminate-to-metal parts bonding; and (5) wing box assembly. The criteria used for reliability and quality assurance are discussed, and several solutions to specific manufacturing problems encountered during fabrication are given. For Vol. 1, see N73-13011; for Vol. 2, see N73-22929.

  3. Development of CFRP Mirrors for Space Telescopes Using Replica Technique

    Science.gov (United States)

    Utsunomiya, Shin; Kamiya, Tomohiro; Shimizu, Ryuzo

    2012-07-01

    Ultra-lightweight and high-accuracy CFRP (Carbon Fiber Reinforced Plastics) mirrors for space telescopes have developed and their feasibility for ultrared applications was demonstrated. The CTE (Coefficient of Thermal Expansion) of the all-CFRP sandwich panels was tailored in ±1x10-7/K. The surface accuracy of mirrors of 150 mm in diameter was 0.8 μm RMS (Root Mean Square) as fabricated and the surface smoothness was improved to 5 nm RMS. The surface of front face skins of sandwich panels was coated with epoxy resin and surface accuracy and smoothness were transcribed from an optically-polished glass tool of λ/20 accuracy by replica technique. Surface preciseness was measured before and after replica coating using a 3D optical profiler of white light interferometer. Observed patterns of the asperity of mirror surfaces were classified into four categories, overall warping and line patterns of fiber tows and core patterns and print-through of individual fibers. Replica improved all kinds of asperity.

  4. Strengthening of Corroded Reinforced SCC-RAP Members with CFRP

    Directory of Open Access Journals (Sweden)

    Ahmed Abdel-Mohti

    2016-01-01

    Full Text Available Corrosion is one of the major problems affecting the durability of reinforced concrete (RC structures. This paper investigates the effect of rebar corrosion on the performance of reinforced self-consolidating concrete (SCC members and the effectiveness of repair. A control RC member, which has no corrosion problem, was prepared to compare against corroded and repaired members. A number of reinforced concrete members having up to 50% corrosion level were constructed and tested to study the effect of corrosion on the structural performance of RC members. The beams with corrosion problem were repaired using carbon fiber reinforced polymer (CFRP sheets and U-wraps. All of the beams constructed, which are either not repaired or repaired, in this study were tested under two static line loads until failure. The effect of corrosion and effectiveness of repairing technique were assessed by evaluating the performance in terms of load carrying capacity, deflection, and ductility. Test results revealed that as the corrosion level increases, the loss in load carrying capacity increases. Repairing using CFRP improved the performance of corroded members. For example, when 50% corrosion level was achieved, the beam lost approximately 57% of its load carrying capacity, but when it was repaired, it recovered about 42% of its load carrying capacity.

  5. Advanced Aircraft Material

    Directory of Open Access Journals (Sweden)

    Vivek Kumar Prince

    2013-06-01

    Full Text Available There has been long debate on “advanced aircraft material” from past decades & researchers too came out with lots of new advanced material like composites and different aluminum alloys. Now days a new advancement that is in great talk is third generation Aluminum-lithium alloy. Newest Aluminum-lithium alloys are found out to have low density, higher elastic modulus, greater stiffness, greater cryogenic toughness, high resistance to fatigue cracking and improved corrosion resistance properties over the earlier used aircraft material as mentioned in Table 3 [1-5]. Comparison had been made with nowadays used composite material and is found out to be more superior then that

  6. Finite Element Analysis for Fatigue Damage Reduction in Metallic Riveted Bridges Using Pre-Stressed CFRP Plates

    Directory of Open Access Journals (Sweden)

    Elyas Ghafoori

    2014-04-01

    Full Text Available Many old riveted steel bridges remain operational and require retrofit to accommodate ever increasing demands. Complicating retrofit efforts, riveted steel bridges are often considered historical structures where structural modifications that affect the original construction are to be avoided. The presence of rivets along with preservation requirements often prevent the use of traditional retrofit methods, such as bonding of fiber reinforced composites, or the addition of supplementary steel elements. In this paper, an un-bonded post-tensioning retrofit method is numerically investigated using existing railway riveted bridge geometry in Switzerland. The finite element (FE model consists of a global dynamic model for the whole bridge and a more refined sub-model for a riveted joint. The FE model results include dynamic effects from axle loads and are compared with field measurements. Pre-stressed un-bonded carbon fiber reinforced plastic (CFRP plates will be considered for the strengthening elements. Fatigue critical regions of the bridge are identified, and the effects of the un-bonded post-tensioning method with different pre-stress levels on fatigue susceptibility are explored. With an applied 40% CFRP pre-stress, fatigue damage reductions of more than 87% and 85% are achieved at the longitudinal-to-cross beam connections and cross-beam bottom flanges, respectively.

  7. In-service Structural Health Monitoring of a Full-scale Composite Horizontal Tail

    Institute of Scientific and Technical Information of China (English)

    WU Zhanjun; GAO Dongyue; WANG Yishou; Gorgin RAHIM

    2015-01-01

    In-service structural health monitoring (SHM) technologies are critical for the utilization of composite aircraft structures. We developed a Lamb wave-based in-service SHM technology using built-in piezoelectric actuator/sensor networks to monitor delamination extension in a full-scale composite horizontal tail. The in-service SHM technology combine of damage rapid monitoring (DRM) stage and damage imaging diagnosis (DID) stage allows for real-time monitoring and long term tracking of the structural integrity of composite aircraft structures. DRM stage using spearman rank correlation coefifcient was introduced to generate a damage index which can be used to monitor the trend of damage extension. The DID stage based on canonical correlation analysis aimed at intuitively highlighting structural damage regions in two-dimensional images. The DRM and DID stages were trialed by an in-service SHM experiment of CFRP T-joint. Finally, the detection capability of the in-service SHM technology was verified in the SHM experiment of a full-scale composite horizontal tail. Experimental results show that the rapid monitoring method effectively monitors the damage occurrence and extension tendency in real time;damage imaging diagnosis results are consistent with those from the failure model of the composite horizontal tail structure.

  8. Comparison of PZT and FBG sensing technologies for debonding detection on reinforced concrete beams strengthened with external CFRP strips subjected to bending loads

    Directory of Open Access Journals (Sweden)

    Sevillano, E.

    2016-06-01

    Full Text Available The development of monitoring technologies particularly suitable to be used with novel CFRP strengthening techniques has gained great attention in recent years. However, in spite of the high performance of these advanced composite materials in the strengthening and repairing of structures in service, they are usually associated with brittle and sudden failure mainly caused by debonding phenomena, originated either at the CFRP-plate end or at the intermediate areas in the vicinity of flexural cracks in the RC beam. Thus, it is highly recommended for these structures to be monitored in order to ensure their integrity while in service. Specifically, the feasibility of smart sensing technologies such as Fiber Bragg Grating (FBG sensors and piezo-impedance transducers (PZT has been studied. To the knowledge of the authors, none serious study has been carried out until now concerned to the topic of damage detection due to debonding in rehabilitated structures with CFRP composites.El desarrollo de tecnologías de monitorización aplicables junto con las novedosas técnicas de refuerzo basadas en materiales CFRP ha recibido una atención creciente los últimos años. Sin embargo, a pesar del alto rendimiento de estos avanzados materiales compuestos en la reparación y refuerzo de estructuras en servicio, están habitualmente asociados a fallos frágiles y repentinos causados principalmente por fenómenos de despegue, originados bien en los extremos del refuerzo, bien en áreas intermedias en las proximidades de grietas de flexión existentes en la viga. Por tanto, es altamente recomendable monitorizar estas soluciones estructurales de cara a garantizar su integridad en servicio. Específicamente, se ha estudiado la viabilidad de sensores inteligentes tales como los sensores Fiber Bragg Grating (FBG o los transductores piezoeléctricos (PZT. Hasta donde los autores saben, no se han realizado estudios serios hasta la fecha abordando la detección de da

  9. ACEE Composite Structures Technology: Review of selected NASA research on composite materials and structures

    Science.gov (United States)

    1984-01-01

    The NASA Aircraft Energy Efficiency (ACEE) Composite Primary Aircraft Structures Program was designed to develop technology for advanced composites in commercial aircraft. Research on composite materials, aircraft structures, and aircraft design is presented herein. The following parameters of composite materials were addressed: residual strength, damage tolerance, toughness, tensile strength, impact resistance, buckling, and noise transmission within composite materials structures.

  10. Program for establishing long-time flight service performance of composite materials in the center wing structure of C-130 aircraft. Phase 5: flight service and inspection. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kizer, J.A.

    1981-10-01

    Inspections of the C-130 composite-reinforced center wings were conducted over the flight service monitoring period of more than six years. Twelve inspections were conducted on each of the two C-130H airplanes having composite reinforced center wing boxes. Each inspection consisted of visual and ultrasonic inspection of the selective boron-epoxy reinforced center wings which included the inspection of the boron-epoxy laminates and the boron-epoxy reinforcement/aluminum structure adhesive bondlines. During the flight service monitoring period, the two C-130H aircraft accumulated more than 10,000 flight hours and no defects were detected in the inspections over this period. The successful performance of the C-130H aircraft with composite-reinforced center wings allowed the transfer of the responsibilities of inspecting and maintaining these two aircraft to the U. S. Air Force.

  11. Atmospheric composition and thermodynamic retrievals from the ARIES airborne TIR-FTS system – Part 2: Validation and results from aircraft campaigns

    Directory of Open Access Journals (Sweden)

    G. Allen

    2014-04-01

    Full Text Available This study validates trace gas and thermodynamic retrievals from nadir infrared spectroscopic measurements recorded by the UK Met Office Airborne Research Interferometer Evaluation System (ARIES – a Thermal InfraRed Fourier Transform Spectrometer (TIR-FTS on the UK Facility for Airborne Atmospheric Measurements (FAAM BAe-146 aircraft. Trace-gas-concentration and thermodynamic profiles have been retrieved and validated for this study throughout the troposphere and planetary boundary layer over a range of environmental variability using data from aircraft campaigns over and around London, the US Gulf Coast, and the Arctic Circle during the ClearfLo, JAIVEX, and MAMM aircraft campaigns, respectively. Vertically-resolved retrievals of temperature and water vapour (H2O, and partial-column retrievals of methane (CH4, carbon monoxide (CO, and ozone (O3, over both land and sea, were compared to corresponding measurements from high-precision in-situ analysers and dropsondes operated on the FAAM aircraft. Average Degrees of Freedom for Signal (DOFS over a 0–9 km column range were found to be 4.97, 3.11, 0.91, 1.10, and 1.62 for temperature, H2O, CH4, CO, and O3, respectively, when retrieved on 10 vertical levels. Partial column mean biases (and 1σ bias averaged across all flight campaigns were −0.4 (±1.9%, −6.0 (±13.1%, −0.6 (±2.1%, −3.0(±18.4%, and +4.7 (±24.9%, respectively, while the typical total a posteriori errors for individually retrieved profiles were 0.4%, 9.5%, 5.0%, 21.2%, and 15.0%, respectively. Averaging kernels derived for progressively lower altitudes show improving sensitivity to lower atmospheric layers when flying at lower altitudes. Temperature and H2O display significant vertically resolved sensitivity throughout the column, whilst trace gases are usefully retrieved only as partial column quantities, with maximal sensitivity for trace gases other than H2O within a layer 1 km and 2 km below the aircraft. This study

  12. Modal content based damage indicators and phased array transducers for structural health monitoring of aircraft structures using ultrasonic guided waves

    Science.gov (United States)

    Ren, Baiyang

    Composite materials, especially carbon fiber reinforced polymers (CFRP), have been widely used in the aircraft industry because of their high specific strength and stiffness, resistance to corrosion and good fatigue life. Due to their highly anisotropic material properties and laminated structures, joining methods like bolting and riveting are no longer appropriate for joining CFRP since they initiate defects during the assembly and severely compromise the integrity of the structure; thus new techniques for joining CFRP are highly demanded. Adhesive bonding is a promising method because it relieves stress concentration, reduces weight and provides smooth surfaces. Additionally, it is a low-cost alternative to the co-cured method which is currently used to manufacture components of aircraft fuselage. Adhesive defects, disbonds at the interface between adherend and adhesive layer, are focused on in this thesis because they can be initialized by either poor surface preparation during the manufacturing or fatigue loads during service. Aircraft need structural health monitoring (SHM) systems to increase safety and reduce loss, and adhesive bonds usually represent the hotspots of the assembled structure. There are many nondestructive evaluation (NDE) methods for bond inspection. However, these methods cannot be readily integrated into an SHM system because of the bulk size and weight of the equipment and requirement of accessibility to one side of the bonded joint. The first objective of this work is to develop instruments, actuators, sensors and a data acquisition system for SHM of bond lines using ultrasonic guided waves which are well known to be able to cover large volume of the structure and inaccessible regions. Different from widely used guided wave sensors like PZT disks, the new actuators, piezoelectric fiber composite (PFC) phased array transducers0 (PAT), can control the modal content of the excited waves and the new sensors, polyvinylidene fluoride (PVDF

  13. Surface Irregularity Factor as a Parameter to Evaluate the Fatigue Damage State of CFRP

    Directory of Open Access Journals (Sweden)

    Pablo Zuluaga-Ramírez

    2015-11-01

    Full Text Available This work presents an optical non-contact technique to evaluate the fatigue damage state of CFRP structures measuring the irregularity factor of the surface. This factor includes information about surface topology and can be measured easily on field, by techniques such as optical perfilometers. The surface irregularity factor has been correlated with stiffness degradation, which is a well-accepted parameter for the evaluation of the fatigue damage state of composite materials. Constant amplitude fatigue loads (CAL and realistic variable amplitude loads (VAL, representative of real in- flight conditions, have been applied to “dog bone” shaped tensile specimens. It has been shown that the measurement of the surface irregularity parameters can be applied to evaluate the damage state of a structure, and that it is independent of the type of fatigue load that has caused the damage. As a result, this measurement technique is applicable for a wide range of inspections of composite material structures, from pressurized tanks with constant amplitude loads, to variable amplitude loaded aeronautical structures such as wings and empennages, up to automotive and other industrial applications.

  14. Nonlinear FE Analysis of Reinforced H.S. Concrete Continuous Beam Strengthened with CFRP Sheet

    Directory of Open Access Journals (Sweden)

    Majid Mohammed Ali Kadhim

    2011-01-01

    Full Text Available This paper is focused on the nonlinear finite element analysis of the reinforced high strength concrete continuous beam strength with carbon fiber reinforced polymer sheet. Three full scale continuous beams are analyzed under two points load; the data of analysis are compared with the experimental data provided by Akbarzadeh and Maghsoudi [1]. ANSYS V.11 program is used in FE analysis, the results obtained from analysis give good agreement with experimental result when compared load-deflection responses, ultimate strength, and the crack patterns. The results showed that with increasing the number of layers, the ultimate strength of beams are increase by amount reached (14% for each layer. The failure mode different by increasing number of CFRP sheet layers when the beam strengthened by one layer of CFRP sheet failed by tensile rupture of CFRP sheet, and beam strengthened by more than one layer failed by intermediate crack (IC debonding of CFRP sheet.

  15. Amphibious Aircraft

    Data.gov (United States)

    National Aeronautics and Space Administration — A brief self composed research article on Amphibious Aircrafts discussing their use, origin and modern day applications along with their advantages and...

  16. Bond Strength Degradation for CFRP and Steel reinforcing Bars in Concrete at Elevated Temperature

    OpenAIRE

    Maluk, Cristian; Bisby, Luke; Terrasi, Giovanni; Green, Mark

    2011-01-01

    Novel concrete elements are emerging utilizing high performance self-consolidating concrete (HPSCC) reinforced with high-strength, lightweight, and non-corroding carbon fiber reinforced polymer (CFRP) prestressed reinforcement. The fire performance of these elements must be understood before they can be used with confidence. In particular, the bond performance of the novel CFRP reinforcement at elevated temperatures requires investigation. This paper examines the bond performance of a specifi...

  17. In-Flight Chemical Composition Observations of Aircraft Emissions using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer

    Science.gov (United States)

    Ziemba, L. D.; Martin, R.; Moore, R.; Shook, M.; Thornhill, K. L., II; Winstead, E.; Anderson, B. E.

    2015-12-01

    Commercial aircraft are an important source of aerosols to the upper troposphere. The microphysical and chemical properties of these emitted aerosols govern their ability to act as ice nuclei, both in near-field contrails and for cirrus formation downstream. During the ACCESS-II (Alternative Fuel Effects on Contrails and Cruise Emissions) campaign, NASA DC-8 CFM56-2-C1 engine emissions were sampled systematically at a range of cruise-relevant thrust levels and at several altitudes. Sampling was done aboard the NASA HU-25 Falcon aircraft, which was equipped with a suite of aerosol and gas-phase instruments focused on assessing the effects of burning different fuel mixtures on aerosol properties and their associated contrails. Here we present in-flight measurements of particle chemical composition made by a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS). The AMS was able to sufficiently resolve near-field (within 100m) aircraft emissions plumes. Low-sulfur HEFA (hydro-processed esters and fatty-acids) and JetA fuels yielded particles that contained 11 and 8% sulfate, respectively, compared to 30% sulfate contribution for traditional JetA fuel. Each of the fuels produced organic aerosol with similarly low oxygen content. Lubrication oils, which are not a combustion product but result from leaks in the engine, were likely a dominant fraction of the measured organic mass based on mass-spectral marker analysis. These results are compared to similar engine conditions from ground-based testing.

  18. The Influence of CFRP Anchorage on Achieving Sectional Flexural Capacity of Strengthened Concrete Beams

    Directory of Open Access Journals (Sweden)

    Hayder A. Rasheed

    2015-12-01

    Full Text Available This research program is intended to verify the influence of using distributed external U-wrap CFRP anchorage to shift the failure mode from overall debonding to sectional flexural failure for concrete beams externally bonded with CFRP sheets. Premature cover delamination and FRP debonding are predominant failure modes in FRP flexural strengthening that may be delayed or prevented by using FRP anchorage. The present experimental study aims to comparatively prove that proper anchorage of flexural strengthening is anticipated to yield a classical flexural failure by FRP rupture or concrete crushing. Once the cohesion of concrete and/or the adhesion with the FRP is exhausted, the U-wraps are engaged to provide anchorage to the flexural FRP through shear friction. Accordingly, three identical T beams and three identical rectangular beams were designed and constructed to examine the capacity improvement by preventing premature debonding failure. The first specimen in each series was tested as a control beam. The second specimen in each series was strengthened using five layers of flexural CFRP in order to admit a debonding failure. The third specimen in each series was strengthened with the same five layers of flexural CFRP plus additional transverse CFRP U-wraps. This study proved that it is possible to quantify the higher flexural capacity of CFRP strengthened beams using external anchorage.

  19. CFRP strengthened openings in two-way concrete slabs

    DEFF Research Database (Denmark)

    Enochsson, O.; Lundqvist, J.; Täljsten, Björn;

    2006-01-01

    are very suitable, not only because of their strength, but also due to that they are easy to apply in comparison to traditional steel girders or other lintel systems. Even though many benefits have been shown by strengthening openings with FRPs not much research have been presented in the literature....... In this paper, laboratory tests on I I slabs with openings, loaded with a distributed load are presented together with analytical and numerical evaluations. Six slabs with openings have been strengthened with carbon fibre reinforced polymers (CFRPs) sheets. These slabs are compared with traditionally steel...... with externally bonded CFRP sheets. The performance is even better than for traditionally steel reinforced slabs. The numerical and analytical evaluations show good agreement with the experimental results. (c) 2006 Elsevier Ltd. All rights reserved....

  20. Analytical and experimental investigation of aircraft metal structures reinforced with filamentary composites. Phase 2: Structural fatigue, thermal cycling, creep, and residual strength

    Science.gov (United States)

    Blichfeldt, B.; Mccarty, J. E.

    1972-01-01

    Specimens representative of metal aircraft structural components reinforced with boron filamentary composites were manufactured and tested under cyclic loading, cyclic temperature, or continuously applied loading to evaluate some of the factors that affect structural integrity under cyclic conditions. Bonded, stepped joints were used throughout to provide composite-to-metal transition regions at load introduction points. Honeycomb panels with titanium or aluminum faces reinforced with unidirectional boron composite were fatigue tested at constant amplitude under completely reversed loading. Results indicated that the matrix material was the most fatigue-sensitive part of the design, with debonding initiating in the stepped joints. However, comparisons with equal weight all-metal specimens show a 10 to 50 times improved fatigue life. Fatigue crack propagation and residual strength were studied for several different stiffened panel concepts, and were found to vary considerably depending on the configuration. Composite-reinforced metal specimens were also subjected to creep and thermal cycling tests. Thermal cycling of stepped joint tensile specimens resulted in a ten percent decrease in residual strength after 4000 cycles.

  1. Aircraft Noise

    Science.gov (United States)

    Michel, Ulf; Dobrzynski, Werner; Splettstoesser, Wolf; Delfs, Jan; Isermann, Ullrich; Obermeier, Frank

    Aircraft industry is exposed to increasing public pressure aiming at a continuing reduction of aircraft noise levels. This is necessary to both compensate for the detrimental effect on noise of the expected increase in air traffic and improve the quality of living in residential areas around airports.

  2. Aircraft Design

    Science.gov (United States)

    Bowers, Albion H. (Inventor); Uden, Edward (Inventor)

    2016-01-01

    The present invention is an aircraft wing design that creates a bell shaped span load, which results in a negative induced drag (induced thrust) on the outer portion of the wing; such a design obviates the need for rudder control of an aircraft.

  3. The NASA Aircraft Energy Efficiency program

    Science.gov (United States)

    Klineberg, J. M.

    1979-01-01

    A review is provided of the goals, objectives, and recent progress in each of six aircraft energy efficiency programs aimed at improved propulsive, aerodynamic and structural efficiency for future transport aircraft. Attention is given to engine component improvement, an energy efficient turbofan engine, advanced turboprops, revolutionary gains in aerodynamic efficiency for aircraft of the late 1990s, laminar flow control, and composite primary aircraft structures.

  4. Calibrated Heat Flow Model for Determining the Heat Conduction Losses in Laser Cutting of CFRP

    Science.gov (United States)

    Mucha, P.; Weber, R.; Speker, N.; Berger, P.; Sommer, B.; Graf, T.

    Laser machining has great potential regarding automation in fabrication of CFRP (carbon-fiber-reinforced plastics) parts, due to the nearly force and tool-wear free processing at high process speeds. The high vaporization temperatures and the large heat conductivity of the carbon fibers lead to a large heat transport into the sample. This causes the formation of a heat-affected zone and a decrease of the process speed. In the present paper,an analytical heat flow model was adapted in order to understand and investigate the heat conduction losses. Thermal sensors were embedded in samples at different distances from the kerf to fit the calculated to the measured temperatures. Heat conduction losses of up to 30% of the laser power were determined. Furthermore, the energy not absorbed by the sample, the energy for sublimating the composite material in the kerf, the energy for the formation of the HAZ, and the residual heat in the sample are compared in an energy balance.

  5. Development of a Low Heat Leak CFRP Stand for Miri Cooler jt Heat Exchanger Stage

    Science.gov (United States)

    Makowski, K. P.; Larson, M. E.; Loc, A. S.; Zhang, B. X.; Leland, R. S.; Hayashi1, B.

    2010-04-01

    A low heat leak stand is being developed for the Heat exchanger Stage Assembly (HSA) of the cryocooler subsystem for the Mid Infra-Red Instrument (MIRI) of the James Webb Space Telescope (JWST). The HSA stand is a hexapod structure supporting the 18 K HSA in a nominal 40 K background environment. Carbon fiber reinforced plastic (CFRP) has been selected for this application to meet the stringent design requirements of a low parasitic heat leak (less than 3.8 mW including both conductive and radiative heat loads for the thermal environment defined above) and a resonance frequency above 120 Hz. A directional lay-up of T300/polycyanate has been chosen for the construction of the hexapod struts. End fittings made of Invar 36 are bonded to the struts to provide structural interfaces. The development effort includes fabricating and testing (including cryogenic thermal cycling) six types of coupons for material characterization, determination of structural degradation due to thermal cycling, and selection of the joint bonding epoxy. Consequently, strut samples are used for final material characterization, performance assessment, and bond joint design evaluation. This paper describes the development process and addresses the challenges in meeting the design requirements. Results of finite element analysis (FEA) for the composite structure and experimental data collected through structural and thermal testing are also presented.

  6. Damage Modes Recognition and Hilbert-Huang Transform Analyses of CFRP Laminates Utilizing Acoustic Emission Technique

    Science.gov (United States)

    WenQin, Han; Ying, Luo; AiJun, Gu; Yuan, Fuh-Gwo

    2016-04-01

    Discrimination of acoustic emission (AE) signals related to different damage modes is of great importance in carbon fiber-reinforced plastic (CFRP) composite materials. To gain a deeper understanding of the initiation, growth and evolution of the different types of damage, four types of specimens for different lay-ups and orientations and three types of specimens for interlaminar toughness tests are subjected to tensile test along with acoustic emission monitoring. AE signals have been collected and post-processed, the statistical results show that the peak frequency of AE signal can distinguish various damage modes effectively. After a AE signal were decomposed by Empirical Mode Decomposition (EMD) method, it may separate and extract all damage modes included in this AE signal apart from damage mode corresponding to the peak frequency. Hilbert-Huang Transform (HHT) of AE signals can clearly illustrate the frequency distribution of Intrinsic Mode Functions (IMF) components in time-scale in different damage stages, and can calculate accurate instantaneous frequency for damage modes recognition to help understanding the damage process.

  7. Development of high performance CFRP shell structures for the pixel detector in the ATLAS experiment at CERN

    CERN Document Server

    Himmel, N; Pfaff, Thomas; Schmitt, Uwe

    2003-01-01

    The "Large Hadron Collider (LHC)" which will be the world's largest and most powerful accelerator and particle collider for particle research experiments is planned to start operation at CERN in 2007. The reported work includes the development of three interleaved cylindrical CFRP shell support structures for a high-resolution detector device within an experimental test equipment named ATLAS, which will be installed into LHC. As the shell structures will be positioned only a few centimetres apart from the point of particle collision, an ultra-light weight component design with extremely tight geometrical tolerances, applying composite materials with extreme stiffness and high radiation hardness is stipulated. The article describes the development of these structures including the design of all components and the manufacturing technology to be used. Furthermore, it reports on geometry testing efforts on a prototype structure to prove the design concept and to derive optimisation potential.

  8. Composition and Trends of Short-Lived Trace Gases in the UT/LS over Europe Observed by the CARIBIC Aircraft

    Science.gov (United States)

    Baker, A. K.; Brenninkmeijer, C. A.; Oram, D. E.; O'Sullivan, D. A.; Slemr, F.; Schuck, T. J.

    2009-12-01

    The CARIBIC project (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) involves the monthly deployment of an instrument container equipped to make atmospheric measurements from aboard a commercial airliner, and has operated since 2005 from aboard a Lufthansa Airbus 340-600 . Measurements from the container include in-situ trace gas and aerosol analyses and the collection of aerosol and whole air samples for post-flight laboratory analysis. Measurements made from the sampling flasks include greenhouse gas (GHG), halocarbon and nonmethane hydrocarbon (NMHC) analysis. CARIBIC flights originate in Frankfurt, Germany with routes to India, East Asia, South America, North America and Africa, and typical aircraft cruising altitudes of 10-12km allow for the monitoring of the upper troposphere/lower stratosphere (UT/LS) along these routes. Data collected during the aircraft’s departure from and return to Frankfurt provide a 4 year time series of near-monthly measurements of the composition of the UT/LS above Europe. Here we present a discussion of the composition of short-lived trace gases in the whole air samples collected above Europe during CARIBIC flights. Over 150 air samples were collected between May 2005 and July 2009, or about 4 samples per month. Of the whole air samples collected, about 45% showed influence by stratospheric air (i.e. very low values of GHG, NMHC and halocarbons, elevated O3, high potential vorticity). The remaining samples were representative of the upper troposphere; back trajectories for these samples indicate that a little over half were collected in air masses that had been in the boundary layer within the previous 8 days. The predominant source regions for these samples were the Gulf of Mexico and continental North America. Owing to their wide range of chemical lifetimes and the varying composition of emissions, short-lived trace gases transported to the UT/LS can be useful indicators of source

  9. Aircraft Structural Analysis, Design Optimization, and Manufacturing Tool Integration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Innovative research is proposed in integrating fundamental aircraft design processes with an emphasis on composite structures. Efficient, lightweight composite...

  10. Fatigue Damage Prognosis in FRP Composites by Combining Multi-Scale Degradation Fault Modes in an Uncertainty Bayesian Framework

    Data.gov (United States)

    National Aeronautics and Space Administration — In this work, a framework for the estimation of the fatigue damage propagation in CFRP composites is proposed. Macro-scale phenomena such as stiffness and strength...

  11. Structural FEM analysis of the strut-to-fuselage joint of a two-seat composite aircraft

    Energy Technology Data Exchange (ETDEWEB)

    Vargas-Rojas, Erik, E-mail: erikvargasrojas@hotmail.com; Camarena-Arellano, Diego, E-mail: erikvargasrojas@hotmail.com; Hernández-Moreno, Hilario, E-mail: erikvargasrojas@hotmail.com [IPN, ESIME Ticomán, Av. Ticomán 600, Col. San José Ticomán 07340 (Mexico)

    2014-05-15

    An analysis of a strut-to-fuselage joint is realized in order to evaluate the zones with a high probability of failure by means of a safety factor. The whole section is analyzed using the Finite Element Method (FEM) so as to estimate static resistance behavior, therefore it is necessary a numerical mock-up of the section, the mechanical properties of the Carbon-Epoxy (C-Ep) material, and to evaluate the applied loads. Results of the analysis show that the zones with higher probability of failure are found around the wing strut and the fuselage joint, with a safety factor lower than expected in comparison with the average safety factor used on aircrafts built mostly with metals.

  12. Structural FEM analysis of the strut-to-fuselage joint of a two-seat composite aircraft

    Science.gov (United States)

    Vargas-Rojas, Erik; Camarena-Arellano, Diego; Hernández-Moreno, Hilario

    2014-05-01

    An analysis of a strut-to-fuselage joint is realized in order to evaluate the zones with a high probability of failure by means of a safety factor. The whole section is analyzed using the Finite Element Method (FEM) so as to estimate static resistance behavior, therefore it is necessary a numerical mock-up of the section, the mechanical properties of the Carbon-Epoxy (C-Ep) material, and to evaluate the applied loads. Results of the analysis show that the zones with higher probability of failure are found around the wing strut and the fuselage joint, with a safety factor lower than expected in comparison with the average safety factor used on aircrafts built mostly with metals.

  13. Research of layered CFRP ultrasonic resonance characteristics based on reflection coefficient modelling%基于反射系数建模的层状 CFRP 超声共振特性研究

    Institute of Scientific and Technical Information of China (English)

    陈越超; 杨辰龙; 周晓军; 郑慧峰

    2016-01-01

    对层状碳纤维复合材料(CFRP)超声反射系数进行建模并研究超声波在 CFRP 内的共振特性。首先建立了声波在多层介质中传播时的反射系数频响模型;在此基础上对多层 CFRP 反射系数频域响应进行数值计算并对反射系数频响随 CFRP 层数的变化特征进行分析;结果表明使用中心频率接近层状 CFRP 固有共振频率的超声探头进行检测时,超声波在层状 CFRP 中将产生共振现象;在 CFRP 层数较少时,共振结构噪声中会夹杂其他频率的信号成分。随着CFRP 层数增加,共振结构噪声在信号共振区域的占比将会提高;当 CFRP 层数增加到一定数量后,共振结构噪声将只在离超声波入射表面较近的区域出现;随着超声波远离入射表面,共振结构噪声将逐渐消失。最后对薄板型 CFRP 和厚截面 CFRP 的实验信号进行分析,得到的实验结果和数值计算结果相一致。%The ultrasonic reflection coefficient model for layered carbon fiber reinforced polymer (CFRP)was built,and the characteristics of ultrasonic resonance in CFRP were studied.First,the reflection coefficient frequency response model of acoustic wave propagation in a multilayered medium was established.Then the frequency response of multilayered CFRP reflection coefficient was numerically calculated based on the model and the influence of the CFRP layer number on the frequency response characteristics was analyzed.The results are as follows.When the ultrasonic probe,whose center frequency is close to the resonant frequency of the layered CFRP,is used to test the CFRP,the ultrasonic wave resonance phenomenon will appear.If the layer number of the CFRP is small,the resonance structure noise will be mixed with signal components of other frequencies.With the increase in the CFRP layer number,the proportion of the resonance structure noise in the signal resonance region will increase.When the CFRP layer increases

  14. Study on shear strengthening of RC continuous T-beams using different layers of CFRP strips

    Energy Technology Data Exchange (ETDEWEB)

    Alferjani, M. B. S.; Samad, A. A. Abdul; Mohamad, Noridah [Faculty of Civil and Environmental Engineering, Universiti Tun Hussein Onn Malaysia, Batu Pahat (Malaysia); Elrawaff, Blkasem S.; Elzaroug, Omer [Faculty of Civil Engineering Omar Al Mukhtar University, Bayda, Libya, Africa (Libya)

    2015-05-15

    Carbon fiber reinforced polymer (CFRP) laminates are externally bonded to reinforced concrete (RC) members to provide additional strength such as flexural, shear, etc. However, this paper presents the results of an experimental investigation for enhancing the shear capacity of reinforced concrete (RC) continuous T- beams using different layers of CFRP wrapping schemes. A total of three concrete beams were tested and various sheet configurations and layouts were studied to determine their effects on ultimate shear strength and shear capacity of the beams. One beam was kept as control beams, while other beams were strengthened with externally bonded CFRP strips with three side bonding and one or two layers of CFRP strips. From the test results, it was found that all schemes were found to be effective in enhancing the shear strength of RC beams. It was observed that the strength increases with the number of sheet layers provided the most effective strengthening for RC continuous T- beam. Beam strengthened using this scheme showed 23.21% increase in shear capacity as compared to the control beam. Two prediction models available in literature were used for computing the contribution of CFRP strips and compared with the experimental results.

  15. Strengthening an in-service reinforcement concrete bridge with prestressed CFRP bars

    Institute of Scientific and Technical Information of China (English)

    Hai-long WANG; Wei-liang JIN; David J.CLELAND; Ai-hui ZHANG

    2009-01-01

    Carbon fiber reinforced polymer(CFRP)bars were prestressed for the structural strengthening of 8 T-shaped rein-forced concrete (RC)beams of a 21-year-old bridge in China.The ultimate bearing capacity of the existing bridge after retrofit was discussed on the basis of concrete structures theory.The flexural strengths of RC beams strengthened with CFRP bars were controlled by the failure of concrete in compression and a prestressing method was applied in the retrofit.The field construction processes of strengthening with CFRP bars-including grouting cracks,cutting groove,grouting epoxy and embedding CFRP bars,surface treating,banding with the U-type CFRP sheets,releasing external prestressed steel tendons-were introduced in detail.In order to evaluate the effectiveness of this strengthening method,field tests using vehicles as live load were applied before and after the retrofit.The test results of deflection and concrete strain of the T-shaped beams with and without strengthening show that the capacity of the repaired bridge,including the bending strength and stiffness,is enhanced.The measurements of crack width also indicate that this strengthening method can enhance the durability of bridges.Therefore,the proposed strengthening technology is feasible and effective.

  16. Study on shear strengthening of RC continuous T-beams using different layers of CFRP strips

    Science.gov (United States)

    Alferjani, M. B. S.; Samad, A. A. Abdul; Elrawaff, Blkasem S.; Elzaroug, Omer; Mohamad, Noridah

    2015-05-01

    Carbon fiber reinforced polymer (CFRP) laminates are externally bonded to reinforced concrete (RC) members to provide additional strength such as flexural, shear, etc. However, this paper presents the results of an experimental investigation for enhancing the shear capacity of reinforced concrete (RC) continuous T- beams using different layers of CFRP wrapping schemes. A total of three concrete beams were tested and various sheet configurations and layouts were studied to determine their effects on ultimate shear strength and shear capacity of the beams. One beam was kept as control beams, while other beams were strengthened with externally bonded CFRP strips with three side bonding and one or two layers of CFRP strips. From the test results, it was found that all schemes were found to be effective in enhancing the shear strength of RC beams. It was observed that the strength increases with the number of sheet layers provided the most effective strengthening for RC continuous T- beam. Beam strengthened using this scheme showed 23.21% increase in shear capacity as compared to the control beam. Two prediction models available in literature were used for computing the contribution of CFRP strips and compared with the experimental results.

  17. Study on shear strengthening of RC continuous T-beams using different layers of CFRP strips

    International Nuclear Information System (INIS)

    Carbon fiber reinforced polymer (CFRP) laminates are externally bonded to reinforced concrete (RC) members to provide additional strength such as flexural, shear, etc. However, this paper presents the results of an experimental investigation for enhancing the shear capacity of reinforced concrete (RC) continuous T- beams using different layers of CFRP wrapping schemes. A total of three concrete beams were tested and various sheet configurations and layouts were studied to determine their effects on ultimate shear strength and shear capacity of the beams. One beam was kept as control beams, while other beams were strengthened with externally bonded CFRP strips with three side bonding and one or two layers of CFRP strips. From the test results, it was found that all schemes were found to be effective in enhancing the shear strength of RC beams. It was observed that the strength increases with the number of sheet layers provided the most effective strengthening for RC continuous T- beam. Beam strengthened using this scheme showed 23.21% increase in shear capacity as compared to the control beam. Two prediction models available in literature were used for computing the contribution of CFRP strips and compared with the experimental results

  18. Vertical and Horizontal Gradients in Aerosol Black Carbon and Its Mass Fraction to Composite Aerosols over the East Coast of Peninsular India from Aircraft Measurements

    Directory of Open Access Journals (Sweden)

    S. Suresh Babu

    2010-01-01

    Full Text Available During the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB experiment of ISRO-GBP, altitude profiles of mass concentrations of aerosol black carbon (MB and total (composite aerosols (MT in the lower troposphere were made onboard an aircraft from an urban location, Chennai (13.04 ∘N, 80.17 ∘E. The profiling was carried out up to 3 km (AGL in eight levels to obtain higher resolution in altitude. Besides, to explore the horizontal gradient in the vertical profiles, measurements were made at two levels [500 m (within ABL and 1500 m (above ABL] from ∼10 N∘ to 16 N∘ and ∼80 E∘ to 84 E∘. The profiles showed a significant vertical extent of aerosols over coastal and offshore regions around Chennai with BC concentrations (∼2 μg m−3 and its contribution to composite aerosols remaining at the same level (between 8 to 10% for FBC as at the surface. Even though the values are not unusually high as far as an urban location is concerned, but their constancy throughout the vertical column will have important implications to climate impact of aerosols.

  19. The Effects of Temperature, Humidity and Aircraft Fluid Exposure on T800H/3900-2 Composites Bonded with AF-555M Adhesive

    Science.gov (United States)

    Miner, Gilda A.; Hou, Tan-Hung; Lowther, Sharon E.; Thibeault, Sheila A.; Connell, John W.; Blasini, Sheila Roman

    2010-01-01

    Fiber reinforced resin matrix composites and structural adhesives have found increased usage on commercial and military aircraft in recent years. Due to the lack of service history of these relatively new material systems, their long-term aging performance has not been well established. In this study, single lap shear specimens (SLS) were fabricated by secondary bonding of Scotch-Weld(TradeMark) AF-555M between pre-cured adherends comprised of T800H/3900-2 uni-directional laminates. The adherends were co-cured with wet peel-ply for surface preparation. Each bond-line of the SLS specimen was measured to determine thickness and inspected visually using an optical microscope for voids. A three-year environmental aging plan for the SLS specimens at 82 C (180 F) and 85% relative humidity was initiated. SLS strengths were measured for both controls and aged specimens at room temperature and 82 C. The effect of this exposure on lap shear strength and failure modes to date is reported. In addition, the effects of water, saline water, deicing fluid, JP-5 jet fuel and hydraulic fluid on both the composite material and the adhesive bonds were investigated. The up to date results on the effects of these exposures will be discussed.

  20. Experimental Test of Stainless Steel Wire Mesh and Aluminium Alloy With Glass Fiber Reinforcement Hybrid Composite

    Directory of Open Access Journals (Sweden)

    Ranga Raj R.,

    2015-05-01

    Full Text Available At present, composite materials are mostly used in aircraft structural components, because of their excellent properties like lightweight, high strength to weight ratio, high stiffness, and corrosion resistance and less expensive. In this experimental work, the mechanical properties of laminate, this is reinforced with stainless steel wire mesh, aluminum sheet metal, perforated aluminum sheet metal and glass fibers to be laminate and investigated. The stainless steel wire mesh and perforated aluminum metal were sequentially stacked to fabricate, hybrid composites. The aluminum metal sheet is also employed with that sequence to get maximum strength and less weight. The tensile, compressive and flexure tests carried out on the hybrid composite. To investigate the mechanical properties and elastic properties of the metal matrix composite laminate of a material we are using experimental test and theoretical calculation. The experimental work consists of Tensile, compressive and flexural test. The expectation of this project results in the tensile and compressive properties of this hybrid composite it is slightly lesser than carbon fibers but it could facilitate a weight reduction compared with CFRP panels. So this hybrid laminates composite material offering significant weight savings and maximum strength over some other GFRP conventional panels.

  1. Matrix phased arrays for the inspection of CFRP-components

    Science.gov (United States)

    Kreutzbruck, M.; Brackrock, D.; Brekow, G.; Montag, H.-J.; Boehm, R.; Illerhaus, B.

    2014-02-01

    Lightweight components are increasingly used in different industrial sectors such as transportation, energy generation and automotive. This growing field includes different types of CFRP-structures, hybrid materials and glued components showing - compared to their pure metallic counterparts- a significant more complicated structure in terms of internal interfaces and anisotropy of material parameters. In this work we present the use of matrix phased array to increase the amount of obtained information to enhance the inspection quality. We used different types of carbon materials such as 6 mm thick uni- and bidirectional prepreg specimens containing impact damages. The latter were introduced with different energy levels ranging from 1.3 to 7.2 J. By scanning a 2.25 MHz matrix array with 6 × 10 elements above the prepreg surface and using different angels of incidence a complete 3D-image was generated which allows the detection of defects as small as 1mm in a depth of 4 mm. A comparison with conventional approaches show that the signal-to-noise ratio can be highly increased. This enables us to visualize the region of damage within the impact zone, clearly showing the cone-like damage distribution along increasing material depth. The detection quality allows the estimation of the opening angles of the cone shaped damage, which can be used for further evaluation and quantitation of energy dependent impact damages.

  2. Matrix phased arrays for the inspection of CFRP-components

    Energy Technology Data Exchange (ETDEWEB)

    Kreutzbruck, M.; Brackrock, D.; Brekow, G.; Montag, H.-J.; Boehm, R.; Illerhaus, B. [BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin (Germany)

    2014-02-18

    Lightweight components are increasingly used in different industrial sectors such as transportation, energy generation and automotive. This growing field includes different types of CFRP-structures, hybrid materials and glued components showing - compared to their pure metallic counterparts- a significant more complicated structure in terms of internal interfaces and anisotropy of material parameters. In this work we present the use of matrix phased array to increase the amount of obtained information to enhance the inspection quality. We used different types of carbon materials such as 6 mm thick uni- and bidirectional prepreg specimens containing impact damages. The latter were introduced with different energy levels ranging from 1.3 to 7.2 J. By scanning a 2.25 MHz matrix array with 6 × 10 elements above the prepreg surface and using different angels of incidence a complete 3D-image was generated which allows the detection of defects as small as 1mm in a depth of 4 mm. A comparison with conventional approaches show that the signal-to-noise ratio can be highly increased. This enables us to visualize the region of damage within the impact zone, clearly showing the cone-like damage distribution along increasing material depth. The detection quality allows the estimation of the opening angles of the cone shaped damage, which can be used for further evaluation and quantitation of energy dependent impact damages.

  3. Damage Assessment of Composite Structures Using Digital Image Correlation

    Science.gov (United States)

    Caminero, M. A.; Lopez-Pedrosa, M.; Pinna, C.; Soutis, C.

    2014-02-01

    The steady increase of Carbon-Fiber Reinforced Polymer (CFRP) Structures in modern aircraft will reach a new dimension with the entry into service of the Boeing 787 and Airbus 350. Replacement of damaged parts will not be a preferable solution due to the high level of integration and the large size of the components involved. Consequently the need to develop repair techniques and processes for composite components is readily apparent. Bonded patch repair technologies provide an alternative to mechanically fastened repairs with significantly higher performance, especially for relatively thin skins. Carefully designed adhesively bonded patches can lead to cost effective and highly efficient repairs in comparison with conventional riveted patch repairs that cut fibers and introduce highly strained regions. In this work, the assessment of the damage process taking place in notched (open-hole) specimens under uniaxial tensile loading was studied. Two-dimensional (2D) and three-dimensional (3D) Digital Image Correlation (DIC) techniques were employed to obtain full-field surface strain measurements in carbon-fiber/epoxy T700/M21 composite plates with different stacking sequences in the presence of an open circular hole. Penetrant enhanced X-ray radiographs were taken to identify damage location and extent after loading around the hole. DIC strain fields were compared to finite element predictions. In addition, DIC techniques were used to characterise damage and performance of adhesively bonded patch repairs in composite panels under tensile loading. This part of work relates to strength/stiffness restoration of damaged composite aircraft that becomes more important as composites are used more extensively in the construction of modern jet airliners. The behaviour of bonded patches under loading was monitored using DIC full-field strain measurements. Location and extent of damage identified by X-ray radiography correlates well with DIC strain results giving confidence to

  4. NDT evaluation of long-term bond durability of CFRP-structural systems applied to RC highway bridges

    Science.gov (United States)

    Crawford, Kenneth C.

    2016-06-01

    The long-term durability of CFRP structural systems applied to reinforced-concrete (RC) highway bridges is a function of the system bond behavior over time. The sustained structural load performance of strengthened bridges depends on the carbon fiber-reinforced polymer (CFRP) laminates remaining 100 % bonded to concrete bridge members. Periodic testing of the CFRP-concrete bond condition is necessary to sustain load performance. The objective of this paper is to present a non-destructive testing (NDT) method designed to evaluate the bond condition and long-term durability of CFRP laminate (plate) systems applied to RC highway bridges. Using the impact-echo principle, a mobile mechanical device using light impact hammers moving along the length of a bonded CFRP plate produces unique acoustic frequencies which are a function of existing CFRP plate-concrete bond conditions. The purpose of this method is to test and locate CFRP plates de-bonded from bridge structural members to identify associated deterioration in bridge load performance. Laboratory tests of this NDT device on a CFRP plate bonded to concrete with staged voids (de-laminations) produced different frequencies for bonded and de-bonded areas of the plate. The spectra (bands) of frequencies obtained in these tests show a correlation to the CFRP-concrete bond condition and identify bonded and de-bonded areas of the plate. The results of these tests indicate that this NDT impact machine, with design improvements, can potentially provide bridge engineers a means to rapidly evaluate long lengths of CFRP laminates applied to multiple highway bridges within a national transportation infrastructure.

  5. Experimental Study of RC Beams Strengthened with CFRP Sheets Under Sustaining Loads

    Institute of Scientific and Technical Information of China (English)

    WANG Wenwei; LI Guo

    2006-01-01

    Seven reinforced concrete (RC) beams strengthened in flexure using carbon fiber reinforced polymer (CFRP) sheets subjected to different sustaining loads were tested. The effects of initial load and load history on the ultimate strength of strengthened RC beams were examined by externally bonded CFRP sheets. The main experimental parameters included different levels of sustaining load at the time of strengthening, and load history. Experimental results show that sustaining load levels at the time of strengthening have important influences on the ultimate strength of strengthened RC beams. If the initial load is the same, the ultimate strength of RC beams strengthened with CFRP sheets is almost the same regardless of load history at the time of strengthening.

  6. Numerical Simulation and Experimental Validation of an Integrated Sleeve-Wedge Anchorage for CFRP Rods

    DEFF Research Database (Denmark)

    Schmidt, Jacob Wittrup; Smith, Scott T.; Täljsten, Björn;

    2011-01-01

    The tensioning of carbon fibre-reinforced polymer (CFRP) rods for prestressed concrete applications or post-tensioning repair and strengthening has met with mixed success. This is primarily due to limitations inherent in the use of traditional wedge anchors typically used for steel tendons....... Recently, an integrated sleeve-wedge anchorage has been successfully developed specifically for CFRP rods. This paper in turn presents a numerical simulation of the newly developed anchorage using ABAQUS. The three-dimensional finite element (FE) model, which considers material non-linearity, uses...... hexagonal elements for the barrel and CFRP rod and tetrahedral elements for the integrated sleeve-wedge. The simulated barrel surface strains are shown to compare well with optically measured strains, however, the numerical results are shown to be sensitive to the mechanical properties of the anchorage...

  7. Pull-out behavior of CFRP single-strap ground anchors

    OpenAIRE

    Fan, Haifeng; Keller, Thomas; Vassilopoulos, Anastasios

    2016-01-01

    Pull-out experiments were performed on four carbon fiber-reinforced polymer (CFRP) ground anchors simulating their applications in rock and soil. The CFRP tendons used in these anchors comprise a single-strap end on both the ground and air sides. On the ground side, the single-strap end is embedded in a cylinder of high-strength grout which fits into the borehole. In rock applications, the ground-side anchor can be used directly without additional confinement, while in the case of soil, an ad...

  8. External post-tensioning of cfrp tendons using integrated sleeve-wedge anchorage

    DEFF Research Database (Denmark)

    Schmidt, Jacob Wittrup; Bennitz, Anders; Goltermann, Per;

    2012-01-01

    Strengthening of structures using external post-tension CFRP systems have proven to be anefficient method as such system increases the structural capacity and reduces cracks and deflection. Sufficient anchorage is of significant importance since the anchorage provides the connection between...... anchorage was obtained using the novel anchorage and that its behaviour is stable and predicatble when short term static load is applied. Desired strengthening was also observed in external post-tensioning on reinforced concrete T-beams. The requirements and definitions on a stable anchorage of CFRP tendons...

  9. Laser ablation of CFRP using picosecond laser pulses at different wavelengths from UV to IR

    Science.gov (United States)

    Wolynski, Alexander; Herrmann, Thomas; Mucha, Patrick; Haloui, Hatim; L'huillier, Johannes

    Laser processing of carbon fibre reinforced plastics (CFRP) has a great industrial relevance for high performance structural parts in airplanes, machine tools and cars. Through-holes drilled by nanosecond laser pulses show thermal induced molten layers and voids. Recently, picosecond lasers have demonstrated the ability to drill high-efficient and high-quality rivet through-holes. In this paper a high-power picosecond laser system operating at different wavelengths (355 nm, 532 nm and 1064 nm) has been used for CFRP ablation experiments to study the influence of different laser parameters in terms of machining quality and processing time.

  10. Fiber optic system for the real time detection, localization, and classification of damage in composite aircraft structures

    Science.gov (United States)

    Mendoza, Edgar; Prohaska, John; Kempen, Connie; Esterkin, Yan; Sun, Sunjian; Krishnaswamy, Sridhar

    2014-05-01

    Acoustic emission is the leading structural health monitoring technique use for the early warning detection of structural damage in advanced composite structures associated with impacts, cracks, fracture, and delaminations. This paper describes progress towards the development of a fiber optic acoustic emission sensor (FAESense™) system based on the use of a novel two-wave mixing interferometer produced on a photonic integrated circuit (PIC) microchip.

  11. Design, ancillary testing, analysis and fabrication data for the advanced composite stabilizer for Boeing 737 aircraft. Volume 1: Technical summary

    Science.gov (United States)

    Aniversario, R. B.; Harvey, S. T.; Mccarty, J. E.; Parsons, J. T.; Peterson, D. C.; Pritchett, L. D.; Wilson, D. R.; Wogulis, E. R.

    1983-01-01

    The horizontal stabilizer of the 737 transport was redesigned. Five shipsets were fabricated using composite materials. Weight reduction greater than the 20% goal was achieved. Parts and assemblies were readily produced on production-type tooling. Quality assurance methods were demonstrated. Repair methods were developed and demonstrated. Strength and stiffness analytical methods were substantiated by comparison with test results. Cost data was accumulated in a semiproduction environment. FAA certification was obtained.

  12. Separation of airborne and structureborne noise radiated by plates constructed of conventional and composite materials with applications for prediction of interior noise paths in propeller driven aircraft. Ph.D. Thesis

    Science.gov (United States)

    Mcgary, M. C.

    1986-01-01

    The anticipated application of advanced turboprop propulsion systems and use of composite materials in primary structure is expected to increase the interior noise of future aircraft to unacceptability high levels. The absence of technically and economically feasible noise source-path diagnostic tools has been a primer obstacle in the development of efficient noise control treatments for propeller driven aircraft. A new diagnostic method which permits the separation and prediction of the fully coherent airborne and structureborne components of the sound radiated by plates or thin shells has been developed. Analytical and experimental studies of the proposed method were performed on plates constructed of both conventional and composite materials. The results of the study indicate that the proposed method can be applied to a variety of aircraft materials, could be used in flight, and has fewer encumbrances than the other diagnostic tools currently available. The study has also revealed that the noise radiation of vibrating plates in the low frequency regime due to combined airborne and structureborne inputs possesses a strong synergistic nature. The large influence of the interaction between the airborne and structureborne terms has been hitherto ignored by researchers of aircraft interior noise problems.

  13. Composites

    Science.gov (United States)

    Taylor, John G.

    The Composites market is arguably the most challenging and profitable market for phenolic resins aside from electronics. The variety of products and processes encountered creates the challenges, and the demand for high performance in critical operations brings value. Phenolic composite materials are rendered into a wide range of components to supply a diverse and fragmented commercial base that includes customers in aerospace (Space Shuttle), aircraft (interiors and brakes), mass transit (interiors), defense (blast protection), marine, mine ducting, off-shore (ducts and grating) and infrastructure (architectural) to name a few. For example, phenolic resin is a critical adhesive in the manufacture of honeycomb sandwich panels. Various solvent and water based resins are described along with resin characteristics and the role of metal ions for enhanced thermal stability of the resin used to coat the honeycomb. Featured new developments include pultrusion of phenolic grating, success in RTM/VARTM fabricated parts, new ballistic developments for military vehicles and high char yield carbon-carbon composites along with many others. Additionally, global regional market resin volumes and sales are presented and compared with other thermosetting resin systems.

  14. CFRP platform and hexapod mount for the Array of MIcrowave Background Anisotropy (AMiBA)

    Science.gov (United States)

    Raffin, Philippe A.; Martin, Robert N.; Huang, Yau-De; Patt, Ferdinand; Romeo, Robert C.; Chen, Ming-Tang; Kingsley, Jeffrey S.

    2004-09-01

    AMiBA consists of a 90 GHz interferometric array telescope with dishes ranging in size from 0.3 to 2.4 meter in diameter, mounted on a 6-meter fully steerable platform. The dishes are attached to the receivers, which are mounted on a platform controlled by a six degree of freedom hexapod mount. The hexapod mount is a parallel connection manipulator also called Stewart Platform. The basic reference for this mechanism is a paper by Stewart. The Stewart Platform is a unique kinematically constrained work platform. It can be manipulated through the six degrees of freedom. The hexapod also provides better accuracy, rigidity, load to weight ratio and load distribution than a serial manipulator or traditional manipulator. The advantages of the hexapod shows that it is a great choice for the AMiBA project. Vertex Antennentechnik GmbH fabricates the hexapod. Testing has started in Germany. The telescope will be delivered in the summer of 2004. The 6m in diameter hexagonal platform is made of carbon fiber reinforced plastics (CFRP) and consists of seven pieces of three different unique types. The platform can be disassembled and fits in a container for transportation. The mounting plane flatness is an important issue for the platform assembly. The deflection angle of the mounting plane relative to any other mounting position must be less than 20 arcsec. Meanwhile, the platform must endure a loading of 3 tons. The platform has been built by Composite Mirror Applications, Inc. (CMA) in Tucson, and mounted on the Hexapod in Germany. This report describes the design and testing of platform and mount for the AMiBA telescope.

  15. Aircraft cybernetics

    Science.gov (United States)

    1977-01-01

    The use of computers for aircraft control, flight simulation, and inertial navigation is explored. The man-machine relation problem in aviation is addressed. Simple and self-adapting autopilots are described and the assets and liabilities of digital navigation techniques are assessed.

  16. Influence of Jet Fuel Composition on Aircraft Engine Emissions: A Synthesis of Aerosol Emissions Data from the NASA APEX, AAFEX, and ACCESS Missions

    Science.gov (United States)

    Moore, R.; Shook, M.; Beyersdorf, A. J.; Corr, C.; Herndon, S. C.; Knighton, W. B.; Miake-Lye, R. C.; Thornhill, K. L., II; Winstead, E.; Yu, Z.; Ziemba, L. D.; Anderson, B. E.

    2015-12-01

    We statistically analyze the impact of jet fuel properties on aerosols emitted by the NASA McDonnell Douglas DC-8 CFM56-2-C1 engines burning fifteen different aviation fuels. Data were collected for this single engine type during four different, comprehensive ground tests conducted over the past decade, which allow us to clearly link changes in aerosol emissions to fuel compositional changes. It is found that the volatile aerosol fraction dominates the number and volume emissions indices (EIs) over all engine powers, which are driven by changes in fuel aromatic and sulfur content. Meanwhile, the naphthalenic content of the fuel determines the magnitude of the non-volatile number and volume EI as well as the black carbon mass EI. Linear regression coefficients are reported for each aerosol EI in terms of these properties, engine fuel flow rate, and ambient temperature, and show that reducing both fuel sulfur content and napththalenes to near-zero levels would result in roughly a ten-fold decrease in aerosol number emitted per kg of fuel burn. This work informs future efforts to model aircraft emissions changes as the aviation fleet gradually begins to transition toward low-aromatic, low-sulfur alternative jet fuels from bio-based or Fischer-Tropsch production pathways.

  17. Study of Composite Laminates Layup Design Method for Civil Aircraft%民用飞机复合材料层压板铺层设计方法研究

    Institute of Scientific and Technical Information of China (English)

    方芳

    2013-01-01

    The key technologies of composite material application for civil aircraft include material choosing, structure design, stress analysis, processing & assembling, structure repair, and airworthiness etc. Based on the study of civil aircraft composite laminates layup design method, the engineering method is used to complete the layup and sizing design at the primary design stage.%在民用飞机复合材料应用中,关键技术领域包括选材、结构设计、强度分析、制件成型及装配工艺、结构修理、适航等。针对民用飞机复合材料层压板铺层设计方法展开研究,在结构初步设计阶段运用工程方法完成结构铺层设计和尺寸设计。

  18. 预应力碳纤维布加固无腹筋混凝土梁试验研究%Experiment Study on Oblique Cross-Section of Concrete Beams Reinforced by Prestressed CFRP

    Institute of Scientific and Technical Information of China (English)

    翟爱良; 王东海; 胡培稳

    2009-01-01

    为改善被加固混凝土梁的抗剪性能,提出在梁底粘贴预应力碳纤维布和在梁端部两侧粘贴碳纤维布复合加固技术.本文设计了五根无腹筋混凝土梁,进行静力加载试验,试验分析预应力碳纤布加固后的斜截面受力性能,研究不同加固方式对混凝土梁的抗剪承载力影响,提出了具有一定工程实用价值的技术结论与建议.%In order to improve the shear capacity of concrete beam,a new composite reinforcement technique that pasting CFRP on both side of the end of the concrete beam and prestressed CFRP at the bottom was used. This paper designed five concrete beams without web reinforcement to carry out static loading experiment and analyzed oblique cross-section mechanical properties of the beams which reinforced by prestressed CFRP through experiment, researched the impact of concrete beams on the shear strength in different reinforcement and made a technical conclusions and recommendations which had a certain practical value.

  19. Application Prospect Analysis of Environmental Protection Composites on Large Passenger Aircraft%环保复合材料在大型客机上的应用前景分析

    Institute of Scientific and Technical Information of China (English)

    张婷

    2013-01-01

    At present, composites widely used in large aircraft are mainly thermosetting resin matrix composites, while the problems of high cost of manufac-ture and dififculty of material recycle restrict its extensive application in aircraft. Today, people pay more and more attention on low cost manufacturing and environmental protection. “Green material” thermoplastic composites could be used as promising alternative materials in large aircraft structure parts owing to its excellent comprehen-sive properties and low cost advantage. In this paper, the possible application of thermoplastic composites in large aircraft are be analyzed from the manufacturing cost, mate-rials performance, materials processing, material recycling and reuse.%目前,在大型客机上广泛应用的复合材料主要是热固性树脂基复合材料,但由于高制造成本及材料难回收等问题,一定程度上制约其在飞机上的应用扩展。在强调低成本制造和环保的今天,“绿色材料”热塑性树脂基复合材料由于其优良的综合性能和低成本优势,可以作为一种有前途的替代材料使用在大型客机结构件上。本文将从热塑性复合材料制件的综合制造成本、性能、工艺以及材料的回收和再利用等方面分析热塑性复合材料在大型客机上的应用前景。

  20. Effects of EB irradiation on stress-strain curves for carbon fiber reinforced composite materials

    Science.gov (United States)

    Kobayashi, H.; Yamada, K.; Mizutani, A.; Uchida, N.; Tanaka, K.; Nishi, Yoshitake

    2004-02-01

    In order to evaluate influence of electron beam (EB) irradiation on elasticity and stress- strain curve of composite materials reinforced by carbon fiber (CF), carbon fiber reinforced polymer (CFRP) and carbon fiber reinforced graphite (C/C) were treated by EB irradiation of 0.3 MGy. Since the EB strengthening was mainly dominated by the ductility enhancements of carbon fiber and matrix of epoxy resin, EB irradiation enlarged fracture stress and enhanced fracture strain of CFRP. Furthermore, EB irradiation slightly enhanced bending elasticity of CFRP and largely enhanced the initial spring constant related to elasticity of C/C coil. Although the elasticity enhancement of carbon fibers did not largely contribute that of CFRP, that of treated graphite matrix in C/C mainly caused the C/C coil elasticity enhancement by EB irradiation. Such a new treatment is a dream-worthy technology for structural materials to be applied in the fields of future engineering.

  1. Study of a reinforced concrete beam strengthened using a combination of SMA wire and CFRP plate

    Science.gov (United States)

    Liu, Zhi-qiang; Li, Hui

    2006-03-01

    Traditional methods used for strengthening of reinforced concrete (RC) structures, such as bonding of steel plates, suffer from inherent disadvantages. In recent years, strengthening of RC structures using carbon fiber reinforced polymer (CFRP) plates has attracted considerable attentions around the world. Most existing research on CFRP plate bonding for flexural strengthening of RC beams has been carried out for the strength enhancement. However, little research is focused on effect of residual deformations on the strengthening. The residual deformations have an important effect on the strengthening by CFRP plates. There exists a very significant challenge how the residual deformations are reduced. Shape memory alloy (SMA) has showed outstanding functional properties as an actuator. It is a possibility that SMA can be used to reduce the residual deformation and make cracks of concrete close by imposing the recovery forces on the concrete in the tensile zone. It is only an emergency damage repair since the SMA wires need to be heated continuously. So, an innovative method of a RC beam strengthened by CFRP plates in combination with SMA wires was first investigated experimentally in this paper. In addition, the nonlinear finite element software of ABAQUS was employed to further simulate the behavior of RC beams strengthened through the new strengthening method. It can be found that this is an excellent and effective strengthening method.

  2. The CFRP primary structure of the MIRI instrument onboard the James Webb Space Telescope

    DEFF Research Database (Denmark)

    Jessen, Niels Christian; Nørgaard-Nielsen, Hans Ulrik; Schroll, J;

    2004-01-01

    The design of the Primary Structure of the Mid Infra-Red Instrument (MIRI) onboard the NASA/ESA James Webb Space Telescope will be presented. The main design driver is the energy flow from the 35 K "hot" satellite interface to the 7 K "cold" MIRI interface. Carbon fibre reinforced plastic (CFRP...

  3. Remote laser cutting of CFRP: influence of the edge quality on fatigue strength

    Science.gov (United States)

    Stock, Johannes W.; Zaeh, Michael F.; Spaeth, Justinian P.

    2014-02-01

    The additional weight of the batteries in electric cars can be compensated by using carbon fiber reinforced plastics (CFRP) for structural parts of the passenger cell. Various machining processes for CFRP are currently subject to investigations. Milling and abrasive waterjet cutting implicate fiber pull out or delamination and, thus, do not thoroughly meet the requirements for mass production. Despite this, laser beam cutting has a great potential in large scale cutting of CFRP and is a predominant research topic. Remote laser beam cutting especially provides a good cut surface quality. Currently, the correlation between cutting parameters and edge quality is not sufficiently known. In particular, studies on the dynamic strength of remote laser cut parts are missing. Therefore, fatigue testing was performed with specimens cut by laser radiation and the results were compared with others made by milling and abrasive waterjet cutting. With these experiments, a comparable study of the different methods of CFRP cutting was achieved. The influence of both the heat affected zone (HAZ) and of defects like micro-fissures on the fatigue strength were evaluated.

  4. Experimental and numerical study of the splaying mode crush of CFRP laminates

    OpenAIRE

    Guillon, Damien; Rivallant, Samuel; Barrau, Jean-Jacques; Petiot, Caroline; Thévenet, Pascal; Malherbe, Benoît

    2009-01-01

    Thanks to an innovative plate crushing test fixture, elementary crushing modes of CFRP laminates have been observed and analysed for static and dynamic loading. These analyses enabled to propose a 2D explicit finite element model at mesoscale for the simulation of splaying mode, with a good correlation between model and test data.

  5. Parameters of static response of carbon fiber reinforced polymer (CFRP) suspension cables

    Institute of Scientific and Technical Information of China (English)

    王立彬; 吴勇

    2015-01-01

    The feasibility of longer spans relies on the successful implementation of new high-strength light weight materials such as carbon fiber reinforced polymer (CFRP). First, a dimensionless equilibrium equation and the corresponding compatibility equation are established to develop the cable force equation and cable displacement governing equation for suspension cables, respectively. Subsequently, the inextensible cable case is introduced. The formula of the Irvine parameter is considered and its physical interpretation as well as its relationship with the chord gravity stiffness is presented. The influences on the increment of cable force and displacement byλ2 and load ratiop′are analyzed, respectively. Based on these assumptions and the analytical formulations, a 2000 m span suspension cable is utilized as an example to verify the proposed formulation and the responses of the relative increment of cable force and cable displacement under symmetrical and asymmetrical loads are studied and presented. In each case, the deflections resulting from elastic elongation or solely due to geometrical displacement are analyzed for the lower elastic modulus CFRP. Finally, in comparison with steel cables, the influences on the cable force equation and the governing displacement equation by span and rise span ratio are analyzed. Moreover, the influences on the static performance of suspension bridge by span and sag ratios are also analyzed. The substantive characteristics of the static performance of super span CFRP suspension bridges are clarified and the superiority and the characteristics of CFRP cable structure are demonstrated analytically.

  6. Strengthening of old metallic structures in fatigue with prestressed and non-prestressed CFRP laminates

    DEFF Research Database (Denmark)

    Täljsten, Björn; Hansen, Christian Skodborg; Schmidt, Jacob Wittrup

    2009-01-01

    Test results and theoretical considerations on four different configurations of strengthened old steel plates with a centre notch loaded in fatigue are presented in this paper. The main interest of the research was to improve fatigue life by adhesive bonding of CFRP laminates on the steel surface...

  7. Tensile and fatigue behaviour of self-piercing rivets of CFRP to aluminium for automotive application

    Science.gov (United States)

    Kang, J.; Rao, H.; Zhang, R.; Avery, K.; Su, X.

    2016-07-01

    In this study, the tensile and fatigue behaviour of self-piercing rivets (SPRs) in carbon fibre reinforced plastic (CFRP) to aluminium 6111 T82 alloys were evaluated. An average maximum lap-shear tensile load capacity of 3858 N was achieved, which is comparable to metal-to-metal SPR lap-shear joints. The CFRP-Al SPRs failed in lap-shear tension due to pull-out of the rivet head from the CFRP upper sheet. The CFRP-Al SPR lap- shear specimens exhibited superior fatigue life compared to previously studied aluminium-to- aluminium SPR lap-shear joints. The SPR lap-shear joints under fatigue loads failed predominantly due to kinked crack growth along the width of the bottom aluminium sheet. The fatigue cracks initiated in the plastically deformed region of the aluminium sheet close to the rivet shank in the rivet-sheet interlock region. Scatter in fatigue life and failure modes was observed in SPR lap-shear specimens tested close to maximum tensile load.

  8. Laser drilling of carbon fiber reinforced plastics (CFRP) by picosecond laser pulses: comparative study of different drilling tools

    Science.gov (United States)

    Herrmann, T.; Stolze, M.; L'huillier, J.

    2014-03-01

    Carbon fiber reinforced plastic (CFRP) as a lightweight material with superior properties is increasingly being used in industrial manufacturing. Using ultrashort laser pulses can improve the quality in cutting or drilling applications, but at high power levels it is more complicated to maintain the accuracy and precision in CFRP drilling. According to the application requirements for the extent of the heat affected zone, the geometric precision and the productivity different drilling tools can be used. Therefore we report on the application of three different beam delivery systems to drilling processes of CFRP: Galvanometer scanner, trepanning head and diffractive optical elements.

  9. Relation between repeatability and speed of robot-based systems for composite aircraft production through multilateration sensor system

    Science.gov (United States)

    Bock, M.; Perner, M.; Krombholz, C.; Beykirch, B.

    2015-03-01

    Fiber composites are becoming increasingly important in different fields of lightweight application. To guarantee the estimated demand of components made of carbon fiber reinforced plastics the use of industrial robots is suggested in production. High velocity of the layup process is addressed to significantly increase the production rate. Today, the layup of the fiber material is performed by gantry systems. They are heavy weight, slow and the variety of possible part shapes is limited. Articulated robots offer a huge operational area in relation to their construction size. Moreover, they are flexible enough to layup fiber material into different shaped molds. Thus, standard articulated robots are less accurate and more susceptible to vibration than gantry systems. Therefore, this paper illustrates an approach to classify volumetric errors to obtain a relation between the achievable speed in production and precision. The prediction of a precision at a defined speed is the result. Based on the measurement results the repeatability of the robotic unit within the workspace is calculated and presented. At the minimum speed that is applicable in production the repeatability is less than 30 mm. Subsequently, an online strategy for path error compensation is presented. The approach uses a multilateration system that consists of four laser tracer units and measures the current absolute position of a reflector mounted at the end-effector of the robot. By calculating the deviation between the planned and the actual position a compensated motion is applied. The paper concludes with a discussion for further investigations.

  10. Large Scale Applications Using FBG Sensors: Determination of In-Flight Loads and Shape of a Composite Aircraft Wing

    Directory of Open Access Journals (Sweden)

    Matthew J. Nicolas

    2016-06-01

    Full Text Available Technological advances have enabled the development of a number of optical fiber sensing methods over the last few years. The most prevalent optical technique involves the use of fiber Bragg grating (FBG sensors. These small, lightweight sensors have many attributes that enable their use for a number of measurement applications. Although much literature is available regarding the use of FBGs for laboratory level testing, few publications in the public domain exist of their use at the operational level. Therefore, this paper gives an overview of the implementation of FBG sensors for large scale structures and applications. For demonstration, a case study is presented in which FBGs were used to determine the deflected wing shape and the out-of-plane loads of a 5.5-m carbon-composite wing of an ultralight aerial vehicle. The in-plane strains from the 780 FBG sensors were used to obtain the out-of-plane loads as well as the wing shape at various load levels. The calculated out-of-plane displacements and loads were within 4.2% of the measured data. This study demonstrates a practical method in which direct measurements are used to obtain critical parameters from the high distribution of FBG sensors. This procedure can be used to obtain information for structural health monitoring applications to quantify healthy vs. unhealthy structures.

  11. Damage Detection in Composite Structures with Wavenumber Array Data Processing

    Science.gov (United States)

    Tian, Zhenhua; Leckey, Cara; Yu, Lingyu

    2013-01-01

    Guided ultrasonic waves (GUW) have the potential to be an efficient and cost-effective method for rapid damage detection and quantification of large structures. Attractive features include sensitivity to a variety of damage types and the capability of traveling relatively long distances. They have proven to be an efficient approach for crack detection and localization in isotropic materials. However, techniques must be pushed beyond isotropic materials in order to be valid for composite aircraft components. This paper presents our study on GUW propagation and interaction with delamination damage in composite structures using wavenumber array data processing, together with advanced wave propagation simulations. Parallel elastodynamic finite integration technique (EFIT) is used for the example simulations. Multi-dimensional Fourier transform is used to convert time-space wavefield data into frequency-wavenumber domain. Wave propagation in the wavenumber-frequency domain shows clear distinction among the guided wave modes that are present. This allows for extracting a guided wave mode through filtering and reconstruction techniques. Presence of delamination causes spectral change accordingly. Results from 3D CFRP guided wave simulations with delamination damage in flat-plate specimens are used for wave interaction with structural defect study.

  12. A Material Model for FE-Simulation of UD Composites

    Science.gov (United States)

    Fischer, Sebastian

    2016-04-01

    Composite materials are being increasingly used for industrial applications. CFRP is particularly suitable for lightweight construction due to its high specific stiffness and strength properties. Simulation methods are needed during the development process in order to reduce the effort for prototypes and testing. This is particularly important for CFRP, as the material is costly. For accurate simulations, a realistic material model is needed. In this paper, a material model for the simulation of UD-composites including non-linear material behaviour and damage is developed and implemented in Abaqus. The material model is validated by comparison with test results on a range of test specimens.

  13. APPLICATION FOR AIRCRAFT TRACKING

    OpenAIRE

    Ostroumov, Ivan; Kuz’menko, Natalia

    2011-01-01

    Abstract. In the article the important problems of software development for aircraft tracking have beendiscussed. Position reports of ACARS have been used for aircraft tracking around the world.An algorithm of aircraft coordinates decoding and visualization of aircraft position on the map has beenrepresented.Keywords: ACARS, aircraft, internet, position, software, tracking.

  14. Experimental Research and Fnite Element Analysis on Steel Bridge Deck in CFRP Reinforced SFRC Pavements%CFRP 增强钢纤维混凝土钢桥面铺装力学性能试验与数值模拟

    Institute of Scientific and Technical Information of China (English)

    徐欣; 方海; 徐超; 刘伟庆; 庄勇

    2015-01-01

    由于我国日益增加的交通量,很多正交异性钢桥面铺装和正交异性钢板在服役期内都出现了很多病害。碳纤维(CFRP)具有轻质、高强、耐腐蚀等优越性,钢纤维混凝土具有沥青混凝土没有的刚度和普通混凝土没有的抗裂性能。对于将这两种材料用于钢桥面铺装中形成的组合桥面板,取涡河大桥主桥钢箱梁的一段正交异性钢板,分别对“无铺装”,“沥青混凝土铺装”,“钢纤维混凝土铺装”3种模型进行有限元模拟,比较正交异性钢板的应力、挠度、铺装层的纵向拉应力和横向拉应力,找出最不利荷载工况及变化规律。通过计算比较“沥青混凝土铺装”、“钢纤维混凝土铺装”和“CFRP -钢纤维混凝土铺装”3种铺装层的纵向和横向拉应力,得出 CFRP 网格筋对铺装层表面拉应力的控制作用。结果表明低弹模铺装时横向拉应力为控制应力,而高弹模铺装时纵向拉应力为控制应力,正交异性钢板应力最大部位发生在横隔板开孔附近,碳纤维网格筋可以有效地降低铺装面层的横向和纵向拉应力。%Most orthotropic steel deck pavements and orthotropic steel plates appeared many seri-ous diseases in the service period because of the increasing traffic in our country.Carbon Fibre Reinforced Polymer(CFRP)has the superiority of light weight,high strength,corrosion resistance and so on.The stiff-ness of bitulith concrete is small and normal concrete crack resistance is poor.But the steel fiber rein-forced concrete has great stiffness and good crack resistance.This paper proposed a new composite deck combined with CFRP and SFRC.An orthotropic plate of Guohe Bridge is calculated as a case.The Stress and deflection of Orthotropic steel plate,the longitudinal tensile stress and transverse tensile stress of pavement have been calculated in three models,including “without pavement”,“with bitumen

  15. 碳纤维复合材料手工制孔刀具和工具的选择方案%Scheme of Choosing Cutting Tool and Tool for Manual Drilling in CFRP

    Institute of Scientific and Technical Information of China (English)

    罗海勇; 郑伟; 涂卿

    2013-01-01

    At present, CFRP is widely applied in aircraft manufacture. Drill is very important process in assembly. So choosing the right cutting tool and tool is very necessary to make sure the quality of drill. Now vari-ous kinds of drills and tools are used in domestic factory. To improve the technology of drill for CFRP, the better scheme should be summarized from practice.%目前,碳纤维复合材料正广泛应用于飞机制造,而装配中制孔是重要的一环,因此,选择合适的刀具和工具是保证制孔质量的前提。国内各公司采用的工具和刀具各不相同,为提高复合材料的制孔技术,应从众多实际应用实例中总结出更优的选择方案。

  16. CFRP-Strengthening and Long-Term Performance of Fatigue Critical Welds of a Steel Box Girder

    Directory of Open Access Journals (Sweden)

    Roland E. Koller

    2014-02-01

    Full Text Available Empa’s research efforts in the 1990s provided evidence that a considerable increase of the fatigue strength of welded aluminum beams can be achieved by externally bonding pultruded carbon fiber reinforced polymer (CFRP laminates using rubber-toughened epoxies over the fatigue-weak welding zone on their tensile flange. The reinforcing effect obtained is determined by the stiffness of the unidirectional CFRP laminate which has twice the elastic modulus of aluminum. One can therefore easily follow that an unstressed CFRP laminate reinforcement of welded beams made of steel will not lead to a substantial increase in fatigue strength of the steel structure. This consideration led to the idea of prestressing an external reinforcement of the welded zone. The present investigation describes experimental studies to identify the adhesive system suitable for achieving high creep and fatigue strength of the prestressed CFRP patch. Experimental results (Wöhler-fields of shear-lap-specimens and welded steel beams reinforced with prestressed CFRP laminates are presented. The paper concludes by presenting a field application, the reinforcement of a steel pendulum by adhesively bonded prestressed CFRP laminates to the tensile flanges of the welded box girder. Inspections carried out periodically on this structure revealed neither prestress losses nor crack initiation after nine years of service.

  17. Modification of strut effectiveness factor for reinforced concrete deep beams strengthened with CFRP laminates

    Directory of Open Access Journals (Sweden)

    Panjehpour, M.

    2014-05-01

    Full Text Available This paper proposes a method to modify the strut effectiveness factor in the strut-and-tie model for CFRP-strengthened reinforced concrete deep beams. Two groups of deep beams comprising six ordinary reinforced concrete deep beams and six CFRP-strengthened reinforced concrete deep beams were experimentally tested under the four-point bending configuration. The shear span-to-effective depth ratio of the beams in each group was 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00. The theoretical principal tensile strain in CFRP-strengthened struts was modified based on a proposed empirical relationship, based on two ratios: the experimental to the theoretical value of principal tensile strain and the shear span-to-effective depth of deep beams.En este trabajo se propone un método en el que se modifica el factor de eficacia que se aplica a las bielas en el modelo de bielas y tirantes para vigas de canto de hormigón reforzadas con laminados CFRP (polímero reforzado con fibras de carbono. Mediante el ensayo a cuatro puntos se determina la resistencia a flexotracción de doce vigas de canto divididas en dos grupos de seis, las del primer grupo de hormigón armado normal y las del segundo de hormigón reforzado con laminados de CFRP. En ambos grupos cada una de las seis vigas se caracteriza por una relación luz de cortante-canto útil distinta, con valores utilizados de: 0.75, 1.00, 1.25, 1.50, 1.75, y 2.00. El valor teórico de la deformación principal por tracción de la biela reforzada con CFRP se modifica de acuerdo con la relación empírica propuesta en este trabajo. Esta se establece a partir de otras dos: la relación entre los valores experimental y teórico de la deformación por tracción principal y la relación luz de cortante-canto útil de las vigas de canto.

  18. Impact of Advanced Propeller Technology on Aircraft/Mission Characteristics of Several General Aviation Aircraft

    Science.gov (United States)

    Keiter, I. D.

    1982-01-01

    Studies of several General Aviation aircraft indicated that the application of advanced technologies to General Aviation propellers can reduce fuel consumption in future aircraft by a significant amount. Propeller blade weight reductions achieved through the use of composites, propeller efficiency and noise improvements achieved through the use of advanced concepts and improved propeller analytical design methods result in aircraft with lower operating cost, acquisition cost and gross weight.

  19. 预应力CFRP/GFRP纤维加固梁的延性性能研究%Ductility Performance of Beams Strengthened with Prestressed CFRP/GFRP Sheets

    Institute of Scientific and Technical Information of China (English)

    张剑; 江雷; 殷王华

    2016-01-01

    碳纤维具有高强度、高弹性模量和延性较差的特点,玻璃纤维相对于碳纤维可起到互补作用,采用预应力碳纤维/玻璃纤维(CFRP/GFRP)加固混凝土梁是一项新的加固技术.基于分层单元理论,建立了加固混凝土梁的计算模型,分析了加固后混凝土梁在荷载作用下三分点加载全过程数据,对比分析了加固梁的屈服荷载、极限荷载、变形和延性性能开展情况,研究了不同混杂纤维配比等对加固梁延性性能的影响.结果表明,将CFRP与GFRP混杂后能充分发挥各自的优势,且能提高预应力纤维加固梁的特征荷载.%Carbon fiber has high tensile strength and modulus of elasticity,but the ductility of the carbon fiber is poor. Relative to the carbon fibers,glass fiber plays a complementary role.It is a new reinforcement technique to reinforce con-crete beams by prestressed CFRP/GFRP.Based on the theory of hierarchical units,a calculation model of reinforced con-crete beam is established for the prestressed strengthened beams in CFRP/GFRP.The overall dates of the concrete beam under loads at three dividing point are analyzed.The comparative analysis of yield load,ultimate load,deformation and duc-tility performance has been worked out and the influence of ductility performance of reinforced beam has been researched in many factors such as the different ratio of hybrid fiber.The results show that when CFRP and GFRP are mixed,the proper-ty and the characteristic loads can both be improved.

  20. Performance of externally CFRP confined RC columns with changes in thickness of the wrap, slenderness of the column and shape of the section

    Directory of Open Access Journals (Sweden)

    Gahmous M.

    2012-09-01

    Full Text Available The present study deals with the analysis of experimental results, in terms of load carrying capacity and strains, obtained from tests on reinforced concrete (RC columns, strengthened with external carbon fiber reinforced polymer (CFRP sheets. The experimental parameters include: number of wrap layers, slenderness of the columns (L/a or L/D and shape of the section (circular and square. A total of 48 specimens were subjected to axial compression. All test specimens were loaded to failure in axial compression. Compressive stress, axial and hoop strains have been recorded to evaluate the stress-strain relationship, ultimate strength, stiffness, and ductility of the specimens. Results clearly demonstrate that composite wrapping can enhance the structural performance of RC columns in terms of both maximum strength and ductility. The effects of test parameters are evidenced and compared.

  1. Synergistic effect of a new wedge-bond-type anchor for CFRP tendons

    Institute of Scientific and Technical Information of China (English)

    谢桂华; 刘荣桂; 陈蓓; 李明君; 石天罡

    2015-01-01

    In order to improve the anchoring force of anchors for carbon fiber reinforced polymer (CFRP) tendons further, a new wedge-bond-type anchor for CFRP tendons was developed. The increment in anchoring force induced by the clamping segment of anchor was studied. Taking the deformation of all parts in clamping segment in the transverse direction into consideration, the calculation formula for the increment of anchoring force was proposed based on the linear elastic hypotheses. The proposed model is verified by experiments and conclusions are drawn that the anchoring force is influenced mainly by the inclination angle of clamping pieces, the length of clamping part and the thickness of bonding medium. Especially, the thickness of bonding medium should be lowered in design to improve the synergistic effect of anchors.

  2. Experimental and Theoretical Analysis of Hollow Steel Columns Strengthening by CFRP

    Directory of Open Access Journals (Sweden)

    Keykha A.H.

    2015-09-01

    Full Text Available The need for strengthening and retrofitting is well known and extensive research is progressing in this field. The reasons for strengthening and retrofitting are numerous: increased loads, changes in use, deterioration, and so on. In recent years, the use of carbon fiber reinforced polymer (CFRP for strengthening has shown to be a competitive method, both regarding structural performance, and economical aspects. Extensive research has been carried out in this field. However, most of the research has been undertaken on concrete structures and for confinement, flexural, and shear strengthening. Limited research has been carried out on steel structures strengthened with CFRP. This paper presents axially loaded steel columns strengthened for increased load. The topic is studied theoretically and through laboratory tests. The theory covers analytical methods. Carbon fiber reinforced polymers has been used to strengthen the columns. The tests have been undertaken on full scale specimens, non-strengthened for reference, partially strengthened and fully strengthened

  3. Experimental investigation on CFRP milling by low power Q-switched Yb:YAG laser source

    Science.gov (United States)

    Genna, S.; Tagliaferri, F.; Papa, I.; Leone, C.; Palumbo, B.

    2016-05-01

    In the present study, laser milling of CFRP plate by means of a 30W Q-Switched Yb:YAG fiber laser is investigated through statistical analysis. Milling tests were performed at the nominal power changing the pulse power; the scanning speed, the hatch distance and the released energy. Design of Experiments (DoE) and ANalysis Of VAriance (ANOVA) were applied with the aim to improve the process performances in term of material removal rate and heat affected zone extension. The results show that, the adopted laser is an effective solution for the CFRP milling. Moreover, adopting an accurate approach to the problem, process variability and material damages can be easily reduced.

  4. Experimental behaviour of RC beams shear strengthened with NSM CFRP laminates

    OpenAIRE

    Dias, Salvador J. E.; Barros, Joaquim A. O.

    2011-01-01

    The near-surface mounted (NSM) is one of the most recent techniques applied for the increase of the shear resistance of reinforced concrete (RC) beams. This technique involves the installation of carbon fibre reinforcement polymers (CFRP) laminates into thin slits open on the concrete cover of the elements to strengthen. The effectiveness of this technique for the shear strengthening of T crosssection RC beams was assessed by experimental research. For this purpose, three inclination...

  5. Evaluation of the performance of full-scale RC beams prestressed with NSM-CFRP laminates

    OpenAIRE

    Costa, Inês; M. Rezazadeh; Barros, Joaquim A. O.

    2014-01-01

    Carbon Fibre Reinforced Polymers (CFRP) applied according to the Near Surface Mounted (NSM) technique are known as capable of increasing the ultimate flexural resistance of Reinforced Concrete (RC) elements, but for Serviceability Limit States (SLS) the load increment it provides is, in general, relatively limited. Recently, researchers are giving attention towards the possibility of applying prestressed NSM-CFRPs to increase significantly the load carrying capacity of RC elements at SLS. As ...

  6. Bond and flexural behavior of concrete elements strengthened with NSM CFRP laminate strips under fatigue loading

    OpenAIRE

    Fernandes, Pedro Miguel Gomes; Silva, Patrícia; Sena-Cruz, José

    2015-01-01

    This paper presents the results of an experimental research on bond and flexural behavior of concrete elements strengthened with carbon fiber reinforced polymer (CFRP) laminate strips under fatigue loading conditions, applied according to the near-surface mounted (NSM) strengthening technique. Long-term performance of the NSM system could be compromised by fatigue loading, which may result in deterioration and weakening of individual components (steel, FRP, concrete), or loss of b...

  7. Assessing the efficiency of CFRP discrete confinement systems for concrete column elements

    OpenAIRE

    Barros, Joaquim A. O.; Ferreira, Débora R. S. M.

    2008-01-01

    Concrete columns requiring strengthening intervention always contain a certain percentage of steel hoops. Applying strips of wet lay-up carbon fiber reinforced polymer (CFRP) sheets in-between the existent steel hoops might, therefore, be an appropriate confinement technique with both technical and economic advantages, when full wrapping of a concrete column is taken as a basis of comparison. To assess the effectiveness of this discrete confinement strategy, circular cross section...

  8. Assessing the efficiency of CFRP discrete confinement systems for concrete cylinders

    OpenAIRE

    Barros, Joaquim; Ferreira, Débora

    2008-01-01

    Concrete columns requiring strengthening intervention always contain a certain percentage of steel hoops. Applying strips of wet lay-up carbon fiber reinforced polymer (CFRP) sheets in-between the existent steel hoops might, therefore, be an appropriate confinement technique with both technical and economic advantages, when full wrapping of a concrete column is taken as a basis of comparison. To assess the effectiveness of this discrete confinement strategy, circular cross section concrete el...

  9. NONLINEAR ANALYSIS OF CFRP- PRESTRESSED CONCRETE BEAMS SUBJECTED TO INCREMENTAL STATIC LOADING BY FINITE ELEMENTS

    OpenAIRE

    Husain M. Husain; Nazar K. Oukaili

    2013-01-01

    In this work a program is developed to carry out the nonlinear analysis (material nonlinearity) of prestressed concrete beams using tendons of carbon fiber reinforced polymer (CFRP) instead of steel. The properties of this material include high strength, light weight, and insusceptibility to corrosion and magnetism. This material is still under investigation, therefore it needs continuous work to make it beneficial in concrete design. Four beams which are tested experimentally by Yan et al. a...

  10. Bond strength of short lap splices in RC beams confined with steel stirrups or external CFRP

    OpenAIRE

    Garcia, R.; Helal, Y.; Pilakoutas, K.; GUADAGNINI, M

    2015-01-01

    This paper investigates the bond behaviour of lapped steel bars using fifteen RC beams tested in flexure. Twelve of the beams were designed to fail by bond splitting at midspan, where the main flexural reinforcement was lapped 10 bar diameters. The parameters studied include the amount and type of confinement at midspan (no confinement, internal steel stirrups or externally bonded carbon FRP), concrete cover and bar size. The results show that the CFRP confinement enhanced the bond strength o...

  11. Experimental Investigation of CFRP Confined Columns Damaged by Alkali Aggregate Reaction

    Directory of Open Access Journals (Sweden)

    Siti Radziah Abdullah

    2012-10-01

    Full Text Available Fiber reinforced polymer is the most effective repair material in use to enhance the strength and ductility of deteriorated reinforced concrete columns. Often, fiber reinforced polymer (FRP provides passive confinement to columns until the dilation and cracking of concrete occurs. In the case of concrete suspected of Alkali Aggregate Reaction (AAR where concrete undergoes expansion, FRP wrap provides active confinement to the expanded concrete. In this study, the performance of carbon fiber reinforced polymer (CFRP wrapped columns damaged by AAR is evaluated based on the number of FRP layers and the time of the polymer application which provides two types of confinement: active or passive. The columns were tested under axial compression to evaluate the residual strength of the columns in comparison with unwrapped columns. The results reveal that the strength of the wrapped columns is enhanced with an increase in the number of CFRP layers. The strength of the columns under passive confinement is higher than the columns under active confinement. Under active confinement, early CFRP wrapping leads to improvement in the strength of the columns.

  12. Helical Milling of CFRP/Ti-6Al-4V Stacks with Varying Machining Parameters

    Institute of Scientific and Technical Information of China (English)

    He Gaiyun; Li Hao; Jiang Yuedong; Qin Xuda; Zhang Xinpei; Guan Yi

    2015-01-01

    The hole-making process in stack materials consisting of carbon fiber reinforced plastics(CFRP) and Ti-6Al-4V remains a critical challenge. In this paper, an experimental study on the helical milling of CFRP/Ti-6Al-4V stacks was conducted by using two different machining strategies. Helical milling strategyⅠmachines both materials with identical machining parameters, while machining strategyⅡuses two sets of machining parameters to machine each material. Helical milling performance was evaluated by the following indicators: tool life, cutting forces, hole quality(including diameter deviation, roundness, roughness, and hole edge quality). The results demonstrate that heli-cal milling strategyⅡoutperformed strategyⅠ, leading to longer tool life(up to 48 holes), smaller cutting forces and better hole quality with higher geometric accuracy and smoother surface finish(Ra≤0.58μm for Ti-6Al-4V and Ra≤0.81μm for CFRP), eliminating the need for reaming or de-burring.

  13. Shear response and design of RC beams strengthened using CFRP laminates

    Science.gov (United States)

    Singh, Shamsher B.

    2013-12-01

    The present investigation addresses the shear strengthening of deficient reinforced concrete (RC) beams using carbon fiber-reinforced polymer (CFRP) sheets. The effect of the pattern and orientation of the strengthening fabric on the shear capacity of the strengthened beams were examined. Three beams with various lay-ups of strengthening fabric, 45°, 0°/90°, and 0°/90°/45° were examined, in addition to an unstrengthened control beam. Principal and shear strains were measured at different locations at the critical sections of the strengthened beams corresponding to each applied shear force. Experimental results showing the advantage of beam strengthened using the various lay-ups of CFRP sheets are discussed. It is concluded that Beam-45°, Beam-0°/90°, and Beam-0°/90°/45° show about 25%, 19%, and 40% increases in shear-load carrying capacity in comparison to the control beam, respectively. Also, there exists a critical value of shear force up to which there is no appreciable shear strain in the CFRP sheets/beam. This shear force marks the ultimate shear resistance of the control beam. However, the strengthened beams exhibited significant strength and stiffness even beyond the critical value of the shear force. A design example for shear strengthening shows that the design equations available in the literature underestimate the actual shear strength of the beams.

  14. Nonlinear finite element modeling of concrete deep beams with openings strengthened with externally-bonded composites

    International Nuclear Information System (INIS)

    Highlights: ► A 3D nonlinear FE model is developed of RC deep beams with web openings. ► We used cohesion elements to simulate bond. ► The developed FE model is suitable for analysis of such complex structures. -- Abstract: This paper aims to develop 3D nonlinear finite element (FE) models for reinforced concrete (RC) deep beams containing web openings and strengthened in shear with carbon fiber reinforced polymer (CFRP) composite sheets. The web openings interrupted the natural load path either fully or partially. The FE models adopted realistic materials constitutive laws that account for the nonlinear behavior of materials. In the FE models, solid elements for concrete, multi-layer shell elements for CFRP and link elements for steel reinforcement were used to simulate the physical models. Special interface elements were implemented in the FE models to simulate the interfacial bond behavior between the concrete and CFRP composites. A comparison between the FE results and experimental data published in the literature demonstrated the validity of the computational models in capturing the structural response for both unstrengthened and CFRP-strengthened deep beams with openings. The developed FE models can serve as a numerical platform for performance prediction of RC deep beams with openings strengthened in shear with CFRP composites.

  15. 航母航空弹药组成及需求分析%The composition and requirement analysis of aviation ammunition in aircraft carrier

    Institute of Scientific and Technical Information of China (English)

    史文强; 陈练; 蒋志勇

    2012-01-01

    为了保证持续的打击能力,舰载机必须往返于航母和战场上空,通过飞行甲板上的挂弹作业完成弹药补给,因而挂弹架次以及弹药需求量对于航空作业的规划安排具有重要意义.针对美国现役“尼米兹”级航母及其舰载机F/A-18E/F“超级大黄蜂”,重点分析了航母航空弹药类型及舰载机挂弹配置;讨论了作战架次的基本组成并总结了挂弹架次计算的基本步骤.以“尼米兹”级和“福特”级航母为例,详细计算了挂弹架次以及航空弹药需求量,并对弹药库自持力进行分析.结果表明,舰载机挂弹架次和航空弹药需求之间存在互相制约的关系.弹药需求量的分析对于航母设计和作战使用具有一定参考价值.%In order to ensure the sustained strike ability,embarked aircraft's should fly between the aircraft carrier and the midair of battlefield,completing the ammunition supplies by ordnance handling on the flight deck. Therefore, arming sortie of embarked aircrafts and requirement for ammunition have an important significance for planning arrangement of aviation operation. Based on the operation experience of USS Niinitz and F/A-l 8E/F Super Hornet onboard, analysis was firstly focused on the main types of aviation ammunition and the basic ordnance configuration for embarked aircraft. Then following by the discussion about breakdown of strike sorties and basic calculation steps of arming sortie, attention was drawn to the detailed calculation of arming sortie and ammunition requirement for USS Nimitz and Ford class aircraft carrier( CVN78). In the end,analysis was also performed on the self-supplying capacity of magazine stock in aircraft carrier. The conclusion is that it is interdependent between the arming sortie and requirement for ammunition. Paper's research production is valuable to the design and operation for aircraft carrier.

  16. Influence of surface preparation on fusion bonding of thermoplastic composites

    NARCIS (Netherlands)

    Sacchetti, F.; Grouve, W.J.B.; Warnet, L.L.; Fernandez Villegas, I.

    2015-01-01

    Carbon fibre-reinforced thermoplastic composites laminates (CFRP) meant for fusion bonding have been moulded using different release media. The potential contamination of the laminate surface by the release media and its effect on the mechanical performance of fusion bonded joints was studied. The p

  17. Experimental and Numerical Research on Seismic Performance of Earthquake-Damaged RC Frame Strengthened with CFRP Sheets

    Directory of Open Access Journals (Sweden)

    Lai Wang

    2016-01-01

    Full Text Available In order to assess the seismic performance of damaged reinforced concrete (RC frame strengthened with carbon fiber reinforced polymers (CFRP sheets, two experimental specimens with identical reinforcement ratio and geometric dimensions were designed following Chinese code for seismic design of buildings. Experimental specimens consist of a reference (undamaged RC frame, namely, KJ-1, and an earthquake-damaged RC frame strengthened with CFRP sheets, namely, KJ-2. A pseudostatic test was conducted on the two specimens to simulate moderate earthquake damage. The strengthening effects of CFRP sheets on damaged RC frame were discussed in terms of hysteretic curve, skeleton curve, stiffness degradation, and ductility. In addition, numerical method based on fiber model method was utilized to analyze the seismic performance of KJ-1 and KJ-2 and it is compared with the experimental result. Both the results confirm that the method of exterior bonding CFRP sheets on the damaged RC frame has restored the seismic performance such as bearing capacity, stiffness, and ductility to its original undamaged level, and some of the seismic performance of the damaged RC frame strengthened with CFRP sheets is even better than the undamaged one, which proves that the method has significant effect in strengthening postearthquake-damaged RC frames.

  18. Experimental research on refractory performance of reinforced concrete beams strengthened with CFRP sheets bonded with an inorganic adhesive

    Institute of Scientific and Technical Information of China (English)

    ZHENG Wen-zhong; WAN Fu-xiong; LI Shi-guang

    2010-01-01

    To meet the requirement of fire endurance for concrete structures strengthened with CFRP sheets,this study develops an inorganic adhesive whose strength at 600℃ is not lower than that at normal room temper ature.The inorganic adhesive is then used to bond CFRP sheets on reinforced concrete beams in order to strengthen them.The fire protection of the CFRP sheets is done using the thick-type fireproofing coatings for tunnel(TFCT)and steel structure(TFCSS)respectively.Four specimens are tested in the furnace together.Specimens are exposed to fire for 1.5 h in according to the ISO834 standard fire curve,and then naturally cooled for 1 h.In the tests,the largest displacements at the mid-span positions of specimens are only from1/1400 to 1/318 of actual span corresponding to the highest temperatures from 300 ℃ to 470 ℃.After the specimens are naturally cooled to the normal temperature and the fireproofing coatings are then removed,it can be seen that the CFRP sheets keep in a good state,which indicates that CFRP sheets can be tightly bonded on the concrete and work well together with the concrete beams during and after fire.Besides,the tests also verify that the fire performance of TFCT is superior to TFCSS for the strengthened beams.

  19. Time-variant flexural reliability of RC beams with externally bonded CFRP under combined fatigue-corrosion actions

    International Nuclear Information System (INIS)

    Time-variant reliability analysis of RC highway bridges strengthened with carbon fibre reinforced polymer CFRP laminates under four possible competing damage modes (concrete crushing, steel rupture after yielding, CFRP rupture and FRP plate debonding) and three degradation factors is analyzed in terms of reliability index β using FORM. The first degradation factor is chloride-attack corrosion which induces reduction in steel area and concrete cover cracking at characteristic key times (corrosion initiation, severe surface cover cracking). The second degradation factor considered is fatigue which leads to damage in concrete and steel rebar. Interaction between corrosion and fatigue crack growth in steel reinforcing bars is implemented. The third degradation phenomenon is the CFRP properties deterioration due to aging. Considering these three degradation factors, the time-dependent flexural reliability profile of a typical simple 15 m-span intermediate girder of a RC highway bridge is constructed under various traffic volumes and under different corrosion environments. The bridge design options follow AASHTO-LRFD specifications. Results of the study have shown that the reliability is very sensitive to factors governing the corrosion. Concrete damage due to fatigue slightly affects reliability profile of non-strengthened section, while service life after strengthening is strongly related to fatigue damage in concrete. - Highlights: • We propose a method to follow the time-variant reliability of strengthened RC beams. • We consider multiple competing failure modes of CFRP strengthened RC beams. • We consider combined degradation mechanisms (corrosion, fatigue, ageing of CFRP)

  20. Acoustic characterization of void distributions across carbon-fiber composite layers

    Science.gov (United States)

    Tayong, Rostand B.; Smith, Robert A.; Pinfield, Valerie J.

    2016-02-01

    Carbon Fiber Reinforced Polymer (CFRP) composites are often used as aircraft structural components, mostly due to their superior mechanical properties. In order to improve the efficiency of these structures, it is important to detect and characterize any defects occurring during the manufacturing process, removing the need to mitigate the risk of defects through increased thicknesses of structure. Such defects include porosity, which is well-known to reduce the mechanical performance of composite structures, particularly the inter-laminar shear strength. Previous work by the authors has considered the determination of porosity distributions in a fiber-metal laminate structure [1]. This paper investigates the use of wave-propagation modeling to invert the ultrasonic response and characterize the void distribution within the plies of a CFRP structure. Finite Element (FE) simulations are used to simulate the ultrasonic response of a porous composite laminate to a typical transducer signal. This simulated response is then applied as input data to an inversion method to calculate the distribution of porosity across the layers. The inversion method is a multi-dimensional optimization utilizing an analytical model based on a normal-incidence plane-wave recursive method and appropriate mixture rules to estimate the acoustical properties of the structure, including the effects of plies and porosity. The effect of porosity is defined through an effective wave-number obtained from a scattering model description. Although a single-scattering approach is applied in this initial study, the limitations of the method in terms of the considered porous layer, percentage porosity and void radius are discussed in relation to single- and multiple-scattering methods. A comparison between the properties of the modeled structure and the void distribution obtained from the inversion is discussed. This work supports the general study of the use of ultrasound methods with inversion to

  1. Key Technology of Advanced Composite Materials from Aircraft to Automobile%先进复合材料从飞机转向汽车应用的关键技术

    Institute of Scientific and Technical Information of China (English)

    张靠民; 李敏; 顾轶卓; 张佐光

    2013-01-01

    Lightweight is a critical approach for sustainable development of auto industry .Advanced composite materials ( ACM) , especially carbon fiber reinforced plastics ( CFRP) , supply the most feasible way due to the lightweight and high strength characteristics.Although there has been forty years since the application of ACM in aviation industry , character-istics of auto industry obviously differ from aviation industry , the most prominent of which is the higher requirement on production efficiency.Taking consideration of the features of ACM in combination with the important requirements of auto industry, the related research plans of developed country and the latest typical applications of ACM in automobile structure were introduced first.On the basis of this, key technologies which block potential application development of ACM in auto industry including integration design and manufacture of composite , low cost carbon fiber, efficient processing and recy-cling issues are discussed, it will be our best wishes if the paper is helpful to develop advanced technology of composite suited auto industry .%轻量化是汽车工业实现可持续发展的重要途径,先进复合材料( Advanced Composite Mate-rials, ACM)特别是碳纤维增强聚合物基复合材料具有质轻高强的性能特点,是最为重要的轻量化材料之一。 ACM在航空工业已有四十年的技术和应用积累,但汽车工业的产业特点明显不同于航空,其中最突出的就是对成本和生产效率的要求更高。因此,将 ACM的技术特点与汽车工业的重要需求相结合,本文首先介绍了碳纤维复合材料用于汽车结构的最新应用进展,列举了发达国家的相关研发计划。在此基础上,从复合材料设计制造一体化、低成本碳纤维、复合材料高效制造和材料循环利用等四个方面讨论了制约汽车用 ACM规模化应用的关键技术。以期为研究发展适合我国汽车工业的

  2. A Simple Buckling Analysis Method for Airframe Composite Stiffened Panel by Finite Strip Method

    Science.gov (United States)

    Tanoue, Yoshitsugu

    Carbon fiber reinforced plastics (CFRP) have been used in structural components for newly developed aircraft and spacecraft. The main structures of an airframe, such as the fuselage and wings, are essentially composed of stiffened panels. Therefore, in the structural design of airframes, it is important to evaluate the buckling strength of the composite stiffened panels. Widely used finite element method (FEM) can analyzed any stiffened panel shape with various boundary conditions. However, in the early phase of airframe development, many studies are required in structural design prior to carrying out detail drawing. In this phase, performing structural analysis using only FEM may not be very efficient. This paper describes a simple buckling analysis method for composite stiffened panels, which is based on finite strip method. This method can deal with isotropic and anisotropic laminated plates and shells with several boundary conditions. The accuracy of this method was verified by comparing it with theoretical analysis and FEM analysis (NASTRAN). It has been observed that the buckling coefficients calculated via the present method are in agreement with results found by detail analysis methods. Consequently, this method is designed to be an effective calculation tool for the buckling analysis in the early phases of airframe design.

  3. Characterisation of CFRP Through Enhanced Ultrasonic Testing Methods

    Science.gov (United States)

    Helfen, T. B.; Venkat, R. Sridaran; Rabe, U.; Hirsekorn, S.; Boller, C.

    2012-12-01

    Carbon fibre reinforced composite materials enjoy an increasing field of application in the aeronautical environment and are due to expand into the automotive and leisure sectors in due course. Those materials need to be qualified at reasonable cost and with considerable experience, where ultrasonic testing has become the procedure of primary choice for nondestructive testing (NDT) so far. However, the two-phase anisotropic structure of a composite material implies a variety of challenges such as scattering, beam skewing, and sound field distortion complicating the localization, sizing, and characterization of defects. Besides qualification during the manufacturing stage, additional tasks emerge once the composite material ages, maybe by mechanical fatigue, chemical ageing, or irradiation. Again characterisation of the material based on ultrasonics would allow comparisons to be made along a material's life cycle. The knowledge generated could be used for in-situ monitoring procedures such as considered in the context of structural health monitoring (SHM).

  4. Study on power consumption of CFRP grinding wheel used in high speed and ultra-high speed grinding%高速超高速磨削用 CFRP 砂轮功率消耗试验研究

    Institute of Scientific and Technical Information of China (English)

    刘勇涛; 傅玉灿; 杨路; 徐九华; 朱鑫乐; 张亮

    2015-01-01

    针对钢基体砂轮质量大、在高速超高速磨削中功率消耗大的问题,从启动功率、空耗功率、磨削功率等几方面,测量并分析了碳纤维增强树脂基复合材料(carbon fiber reinforced polymer,CFRP)基体砂轮与钢基体砂轮功率消耗的情况。试验结果表明:与钢基体砂轮相比,CFRP 砂轮的质量轻,能够有效减小砂轮在高速超高速磨削中的启动功率、空耗功率以及磨削功率;验证了 CFRP 砂轮在高速超高速磨削中减轻主轴负荷、减少能源消耗的优越性能。%In high speed and ultra-high speed grinding power consumption of steel substrate grinding wheel with large mass is high Aimed at this problem the power consumption situation which consisted of starting power depletion power and grinding power of CFRP substrate grinding wheel and steel substrate grinding wheel was measured and analyzed The results indicated that compared with steel substrate grinding wheel the lighter CFRP grinding wheel could effectively reduce power consumption of the spindle Also the superior performances of CFRP grinding wheel in reducing the spindle load and energy consumption were verified.

  5. The drive for Aircraft Energy Efficiency

    Science.gov (United States)

    James, R. L., Jr.; Maddalon, D. V.

    1984-01-01

    NASA's Aircraft Energy Efficiency (ACEE) program, which began in 1976, has mounted a development effort in four major transport aircraft technology fields: laminar flow systems, advanced aerodynamics, flight controls, and composite structures. ACEE has explored two basic methods for achieving drag-reducing boundary layer laminarization: the use of suction through the wing structure (via slots or perforations) to remove boundary layer turbulence, and the encouragement of natural laminar flow maintenance through refined design practices. Wind tunnel tests have been conducted for wide bodied aircraft equipped with high aspect ratio supercritical wings and winglets. Maneuver load control and pitch-active stability augmentation control systems reduce fuel consumption by reducing the drag associated with high aircraft stability margins. Composite structures yield lighter airframes that in turn call for smaller wing and empennage areas, reducing induced drag for a given payload. In combination, all four areas of development are expected to yield a fuel consumption reduction of 40 percent.

  6. Propulsion controlled aircraft computer

    Science.gov (United States)

    Cogan, Bruce R. (Inventor)

    2010-01-01

    A low-cost, easily retrofit Propulsion Controlled Aircraft (PCA) system for use on a wide range of commercial and military aircraft consists of an propulsion controlled aircraft computer that reads in aircraft data including aircraft state, pilot commands and other related data, calculates aircraft throttle position for a given maneuver commanded by the pilot, and then displays both current and calculated throttle position on a cockpit display to show the pilot where to move throttles to achieve the commanded maneuver, or is automatically sent digitally to command the engines directly.

  7. Stochastic finite element analysis of long-span bridges with CFRP cables under earthquake ground motion

    Indian Academy of Sciences (India)

    Özlem Çavdar; Alemdar Bayraktar; Süleyman Adanur; Hasan Basri Başaǧa

    2010-06-01

    Stochastic seismic analysis of long-span bridges with Carbon fibre reinforced polymer (CFRP) cables are presented in this study through combination of the advantages of the perturbation based stochastic finite element method (SFEM) and Monte Carlo simulation (MCS) method. Jindo cable-stayed and Fatih Sultan Mehmet (Second Bosporus) suspension bridges are chosen as an example. Carbon fibre reinforced polymer cable (CFRP) and steel cables are used separately, in which the cable’s cross sectional area is determined by the principle equivalent axial stiffness. Geometric nonlinear effects are considered in the analysis. Uncertainties in the material are taken into account and Kocaeli earthquake in 1999 is chosen as a ground motion. The efficiency and accuracy of the proposed algorithm are validated by comparing with results of MCS method. It can be stated that using of CFRP cables in long-span bridges subjected to earthquake forces is feasible.

  8. Multifunctional Composite Materials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Polymeric composite materials that are currently utilized in aircraft structures are susceptible to significant damage from lightning strikes. Enhanced electrical...

  9. Experimental Study and Nonlinear FEM Analysis on Seismic Performance of CFRP Steel Tube Composite Columns Filled with Steel Reinforced Concrete%碳纤维钢骨-钢管混凝土柱抗震性能试验与有限元分析

    Institute of Scientific and Technical Information of China (English)

    徐亚丰; 王越

    2013-01-01

    In order to research the mechanical properties of carbon fiber steel tube composite columns filled with steel reinforced concrete under low frequency cyclic loads to provide a reference for practical engineering application,3 specimens of different axial compression ratio are on the pseudo-static test and load displacement component hysteretic curve,skeleton curve,ductility coefficient of mechanics performance is analyzed.At the same time,the large-scale general finite element analysis software ABAQUS is adopted to the numerical analysis and experimental verification of hysteretic performance of carbon fiber reinforced concrete filled steel tube columns.The simulation results of carbon fiber steel tube composite columns filled with steel reinforced concrete are in good agreement with experimental results.No matter how to change axial compression ratio,load-displacement hysteretic curves graphics has good stability and curve graph are plump spindle or arched without significant pinch phenomenon.It shows that the plastic deformation ability of the components is strong.As the axial compression ratio increases,the skeleton curve appears obvious decline and the ultimate bearing capacity of the component reduces and extreme value point corresponding to the displacement is smaller.Limit load and limit displacement and ductility coefficient decreases with the increasing of axial compression ratio.The carbon fiber steel tube composite columns fiiled with steel reinforced concrete has good ductility,good seismic performance,adaptation combined with practical engineering applications.%目的 研究碳纤维钢骨-钢管混凝土柱在低周往复荷载作用下的力学性能,为实际工程应用提供参考.方法 制作了3个试件并对其进行拟静力试验,分析不同轴压比下构件的荷载-位移滞回曲线、骨架曲线、延性系数等力学性能.同时采用ABAQUS对碳纤维钢骨-钢管混凝土柱的滞回性能进行了数值分析及试验

  10. Terahertz Wave Approach and Application on FRP Composites

    Directory of Open Access Journals (Sweden)

    Kwang-Hee Im

    2013-01-01

    Full Text Available Terahertz (THz applications have emerged as one of the most new powerful nondestructive evaluation (NDE techniques. A new T-ray time-domain spectroscopy system was utilized for detecting and evaluating orientation influence in carbon fiber-reinforced plastics (CFRPs composite laminates. Investigation of terahertz time-domain spectroscopy (THz-TDS was made, and reflection and transmission configurations were studied as a nondestructive evaluation technique. Here, the CFRP composites derived their excellent mechanical strength, stiffness, and electrical conductivity from carbon fibers. Especially, the electrical conductivity of the CFRP composites depends on the direction of unidirectional fibers since carbon fibers are electrically conducting while the epoxy matrix is not. In order to solve various material properties, the index of refraction (n and the absorption coefficient (α are derived in reflective and transmission configurations using the terahertz time-domain spectroscopy. Also, for a 48-ply thermoplastic polyphenylene-sulfide-(PPS- based CFRP solid laminate and nonconducting materials, the terahertz scanning images were made at the angles ranged from 0° to 180° with respect to the nominal fiber axis. So, the images were mapped out based on the electrical field (E-field direction in the CFRP solid laminates. It is found that the conductivity (σ depends on the angles of the nominal axis in the unidirectional fiber.

  11. Thermal conductivity measurement below 40 K of the CFRP tubes for the Mid-Intrared Instrument mounting struts

    DEFF Research Database (Denmark)

    Shaughnessy, B. M.; Eccleston, P.; Fereday, K. J.;

    2007-01-01

    The Mid-Infrared Instrument (MIRI) is one of four instruments on the James Webb Space Telescope observatory, scheduled for launch in 2013. It must be cooled to about 7 K and is supported within the telescope’s 40 K instrument module by a hexapod of carbon fibre reinforced plastic (CFRP) tubing. T....... This article describes the measurement of cryogenic thermal conductivity of the candidate CFRP. Measured thermal conductivities were about 0.05 W/m K at a mean temperature of 10 K increasing to about 0.20 W/m K at a mean temperature of 40 K....

  12. Experimental investigation of reinforced concrete beams with and without CFRP wrapping

    Science.gov (United States)

    Venkatesha, K. V.; Dinesh, S. V.; Balaji Rao, K.; Bharatkumar, B. H.; Balasubramanian, S. R.; Iyer, Nagesh R.

    2012-11-01

    This paper presents the results of experimental investigations on six reinforced concrete beams, with three different shear span-to-depth ratios, which were tested under two-point loading. The aim of the work was to study the efficacy of Carbon Fibre Reinforced Polymer (CFRP) strips in enhancing shear capacity and/or changing the failure mode from brittle shear failure to ductile flexural failure. The results of the study indicate that while there is a marginal increase in first crack and ultimate loads, it is possible to achieve a change in the failure mode, and the monitored strain gauge data can be used to explain the failure pattern observed.

  13. Numerical Study of Bird Impact on the Aircraft Windshield Structure with Composite Material%民机机头复合材料风挡结构鸟撞分析

    Institute of Scientific and Technical Information of China (English)

    简成文; 李书

    2015-01-01

    The relative velocity is always very large when the bird impacting on the aircraft windshield, and the body of the bird will present the property of fluid. This kind of problem belongs to the category of fluid dynamics. At first, this paper analyzed a numerical simulation of bird impacting on aluminum plate with the method of ALE, and the result of simulation and the test data are compared. Then a full scale model which contains windshield, framework and the skin is set up. The framework and the skin are made of composite materials. Numerical study of bird strike on this model is done and the result proves that the structure meets the design requirements. At present, a full scale framework of aircraft windshield with composite materials has not been applied to the civil aircraft yet, so the study of this windshield structure with composite materials is of great significance.%在鸟体撞击风挡结构过程中,鸟体与风挡结构撞击相对速度很大,呈现出流体特性,属于典型的流固耦合瞬态冲击动力学问题。首先针对文献中的鸟撞铝板试验采用任意的拉格朗日-欧拉( ALE )流固耦合方法进行了分析,对计算方法与鸟体模型进行了验证。然后建立了包括风挡玻璃、风挡骨架以及蒙皮在内的民机全尺寸风挡结构抗鸟撞动响应分析的有限元模型,进行了鸟撞数值模拟,其中风挡骨架与蒙皮采用复合材料。全尺寸的复合材料风挡骨架目前还没有应用到民机上,因此,对复合材料风挡结构的研究是很有意义的。

  14. Fracture morphology of carbon fiber reinforced plastic composite laminates

    Directory of Open Access Journals (Sweden)

    Vinod Srinivasa

    2010-09-01

    Full Text Available Carbon fiber reinforced plastic (CFRP composites have been extensively used in fabrication of primary structures for aerospace, automobile and other engineering applications. With continuous and widespread use of these composites in several advanced technology, the frequency of failures is likely to increase. Therefore, to establish the reasons for failures, the fracture modes should be understood thoroughly and unambiguously. In this paper, CFRP composite have been tested in tension, compression and flexural loadings; and microscopic study with the aid of Scanning Electron Microscope (SEM has been performed on failed (fractured composite surfaces to identify the principle features of failure. Efforts have been made in correlating the fracture surface characteristics to the failure mode. The micro-mechanics analysis of failure serves as a useful guide in selecting constituent materials and designing composites from the failure behavior point of view. Also, the local failure initiation results obtained here has been reliably extended to global failure prediction.

  15. Behaviors of super-long span prestressed cable-stayed bridge with CFRP cables and UHPC girder%CFRP拉索预应力超高性能混凝土斜拉桥力学性能分析

    Institute of Scientific and Technical Information of China (English)

    方志; 任亮; 凡凤红

    2012-01-01

    To discuss the applicability of carbon fiber reinforced polymer (CFRP) cables and reactive powder concrete ( RPC) in super-long span cable-stayed bridges, taking a 1 008 m cable-stayed bridge using steel girder and steel cables as example, a cable-stayed bridge with the same span using RPC (reactive powder concrete) as the girder and advanced composite material CFRP (carbon fiber reinforced polymer) as the cable was designed, in which the cable cross section was determined by the principles of equivalent cable strength and the beam cross section was determined considering the stiffness, shear capacity and local stability. Based on the method of finite element analysis, the comparative study of these two structures on their static properties, dynamic properties, stability and wind resistance were carried out. The results show that it is feasible for using RPC as the girder and CFRP as the cable so as to form a highly efficient, durable cable-stayed bridge of concrete structure and make its applicable span reach about 1 000 m long.%为了探讨碳纤维复合材料(carbon fiber reinforced polymer,CFRP)和超高性能活性粉末混凝土(reactive powder concrete,RPC)在超大跨度斜拉桥中应用的可行性,以主跨1008m的大跨度钢主梁斜拉桥设计方案为例,采用拉索的等强度原则将原桥钢索替换成CFRP索,考虑截面刚度、截面应力和局部稳定等要求,将原桥钢主梁替换成RPC主梁,拟订了一座等跨度的CFRP拉索、RPC主梁斜拉桥方案.采用有限元法分别对两种方案结构的静力特性、动力特性、稳定性能以及抗风性能等进行了分析与比较.结果表明:从结构受力性能角度而言,采用超高性能混凝土主梁和CFRP拉索构成千米级跨度混凝土斜拉桥的结构体系是可行的.

  16. Aircraft Lightning Electromagnetic Environment Measurement

    Science.gov (United States)

    Ely, Jay J.; Nguyen, Truong X.; Szatkowski, George N.

    2011-01-01

    This paper outlines a NASA project plan for demonstrating a prototype lightning strike measurement system that is suitable for installation onto research aircraft that already operate in thunderstorms. This work builds upon past data from the NASA F106, FAA CV-580, and Transall C-180 flight projects, SAE ARP5412, and the European ILDAS Program. The primary focus is to capture airframe current waveforms during attachment, but may also consider pre and post-attachment current, electric field, and radiated field phenomena. New sensor technologies are being developed for this system, including a fiber-optic Faraday polarization sensor that measures lightning current waveforms from DC to over several Megahertz, and has dynamic range covering hundreds-of-volts to tens-of-thousands-of-volts. A study of the electromagnetic emission spectrum of lightning (including radio wave, microwave, optical, X-Rays and Gamma-Rays), and a compilation of aircraft transfer-function data (including composite aircraft) are included, to aid in the development of other new lightning environment sensors, their placement on-board research aircraft, and triggering of the onboard instrumentation system. The instrumentation system will leverage recent advances in high-speed, high dynamic range, deep memory data acquisition equipment, and fiber-optic interconnect.

  17. Porosity and Inclusion Detection in CFRP by Infrared Thermography

    Directory of Open Access Journals (Sweden)

    C. Toscano

    2012-01-01

    Full Text Available The ever wide use of composite materials in the aeronautical industry has evidenced the need for development of ever more effective nondestructive evaluation methodologies in order to reduce rejected parts and to optimize production costs. Infrared thermography has been recently enclosed amongst the standardized non destructive testing techniques, but its usefulness needs still complete assessment since it can be employed in several different arrangements and for many purposes. In this work, the possibility to detect slag inclusions and porosity is analyzed with both lock-in themography and pulse thermography in the transmission mode. To this end, carbon-fiber-peinforced polymers different specimens are specifically fabricated of several different stacking sequences and with embedded slag inclusions and porosity percentages. As main results, both of the techniques are found definitely able to reveal the presence of the defects above mentioned. Moreover, these techniques could be considered complementary in order to better characterize the nature of the detected defects.

  18. Quantification of fatigue state in CFRP using ultrasonic birefringence

    Science.gov (United States)

    Fey, Peter; Kreutzbruck, Marc

    2016-02-01

    Fiber reinforced plastics are widely used in high performance application areas such as aerospace, automotive and wind energy. They are preferred over classic materials such as metals because of their superior weight to stiffness ratio. When subjected to cyclic or static loading, micro-cracks develop and hence their stiffness degrades. The rate of stiffness degradation depends on the angle between the fibers and the applied load. Because commonly used fiber reinforced composites consist of multiple layers with different fiber directions to cope with different loads applied to the material, the stiffness degradation has to be analyzed for each fiber direction. One method to analyze the stiffness degradation in fiber reinforced materials is ultrasonic birefringence. A birefringent effect as it is known for light in optics is also observed for ultrasonic shear waves in fiber reinforced composites because of their elastic anisotropy. The role of the polarization dependent refractive index is taken by the propagation velocity of shear waves. If polarized parallel to the fiber direction they have a higher velocity than polarized perpendicularly to the fiber direction. The velocity depends on shear stiffness of the material. A model to predict the behavior of shear waves in multi-ply layups has been presented previously by Rheinfurth, Fey, Allinger and Busse[1]. That model was used to manually match measured and simulated phase and amplitude curves for waves that traversed the material under different angles between polarization direction of the emitting transducer and fiber direction in the first ply. Here another mode of interpreting the simulated results is used: amplitude and phase for each transducer orientation angle are combined to a complex number. Displaying them in the complex plane for one half rotation of the transducer yields an ellipse. Semi axis lengths and orientation can be obtained by Fourier transform and are used to compare the simulation to measured

  19. Cost and Ductility Effectiveness of Concrete Columns Strengthened with CFRP and SFRP Sheets

    Directory of Open Access Journals (Sweden)

    Khaled Abdelrahman

    2014-05-01

    Full Text Available Recently, steel fibre reinforced polymers (SFRP sheets have been introduced for the repair and rehabilitation of concrete structures. Few researchers studied the behaviour of the concrete columns wrapped with SFRP sheets; however, several critical parameters such as the cost and ductility effectiveness of the SFRP wrapped concrete columns have been lightly addressed. Thus, the main objective of this paper is to study the cost and ductility effectiveness of SFRP wrapped concrete columns and compare the results with the conventionally used carbon FRP (CFRP wrapped concrete columns. In addition, an analytical procedure to predict the cost effectiveness of SFRP wrapped concrete columns is also suggested, from which, a parametric study was conducted. The parametric study investigated the effect of the concrete strength, the number of SFRP layers, and the size and slenderness effects on the cost effectiveness of the concrete columns wrapped with SFRP sheets. The results from the cost and ductility effectiveness study indicated that the SFRP wrapped concrete columns showed enhanced performance over the CFRP wrapped concrete columns. The suggested analytical procedure proved to be a reliable and accurate method to predict the cost effectiveness parameter of SFRP wrapped concrete columns. The parametric study showed the significant impact of the investigated parameters on the cost effectiveness of concrete columns wrapped with SFRP sheets.

  20. Study on electromechanical impedance characteristics of part of structures made of CFRP

    Science.gov (United States)

    Malinowski, Paweł H.; Wandowski, Tomasz; Ostachowicz, Wiesław M.

    2016-04-01

    Carbon Fibre Reinforced Polymers (CFRP) are more and more used in many branches of industry. Researchers are developing numerous techniques of non-destructive assessment of the structures made out of CFRP such as guided waves, ultrasonics, laser induced fluorescence and others. In this research we focus on electromechanical impedance (EMI) technique. In this technique a piezoelectric sensor is either surface mounted or embedded into investigated host structure. The electrical quantities of the sensor are measured for wide frequency range. Due to piezoelectric effect the electrical response of the sensor is related to mechanical response of the structure to which the sensors is bonded to. In the reported research impedance spectra in the vicinity of the transducer thickness mode were investigated as well as the lower frequency range. The spectra that were analysed were gathered from samples with surface treatment such as thermal degradation and samples adhesively bonded with film adhesive with symmetric and unsymmetric bond. Moreover, the samples with modified adhesive bonds were investigated. These spectra for different cases were compared with reference measurement results gathered from pristine samples. Numerical indexes for comparison of the EMI characteristics were proposed. The comparison of the indexes was also conducted. In the experimental part of the research the piezoelectric transducer was mounted at the sample surface. Measurements were conducted using HIOKI Impedance Analyzer IM3570.

  1. Pulsed thermographic inspection of CFRP structures: experimental results and image analysis tools

    Science.gov (United States)

    Theodorakeas, P.; Avdelidis, N. P.; Ibarra-Castanedo, C.; Koui, M.; Maldague, X.

    2014-03-01

    In this study, three different CFRP specimens with internal artificial delaminations of various sizes and located at different depths were investigated by means of Pulsed Thermography (PT) under laboratory conditions. The three CFRP panels, having the same thickness and defects characteristics but with a different shape (planar, trapezoid and curved), were assessed after applying various signal processing tools on the acquired thermal data (i.e. Thermographic Signal Reconstruction, Pulsed Phase Thermography and Principal Component Thermography). The effectiveness of the above processing tools was initially evaluated in a qualitative manner, comparing the imaging outputs and the information retrieval in terms of defect detectability enhancement and noise reduction. Simultaneously, the produced defect detectability was evaluated through Signal-to-Noise Ratio (SNR) computations, quantifying the image quality and the intensity contrast produced between the defected area and the adjacent background area of the test panel. From the results of this study, it can be concluded that the implementation of PT along with the application of advanced signal processing algorithms can be a useful technique for NDT assessment, providing enhanced qualitative information. Nevertheless, SNR analysis showed that despite the enhanced visibility resulting from these algorithms, these can be properly applied in order to retrieve the best possible information according to the user's demands.

  2. Numerical Determination of Shear Strength of Steel Reinforced Concrete Column Strengthened by CFRP Sheets

    Institute of Scientific and Technical Information of China (English)

    王铁成; 余流; 王立军

    2003-01-01

    The earthquake-resistant property of reinforced concrete members depends on the interaction between reinforcing bars and surrounding concrete through bond to a large degree. In this paper a general system aimed at dealing with the failure analysis of reinforced concrete columns strengthened with carbon-fiber-reinforced plastic (CFRP) sheets including bond-slip of the anchored reinforcing bars at the foot of the columns is presented. It is based on the yield design theory with a mixed modeling of the structure, according to which the concrete material is treated as a classical two-dimensional continuum, whereas the longitudinal reinforcing bars are regarded as one-dimensional rods including bond-slip at the foot of the columns. In shear reinforced zones both the shear CFRP sheets and transverse reinforcing bars are incorporated in the analysis through a homogenization procedure and they are only in tension. The approach is then implemented numerically by means of the finite-element formulation. The numerical procedure produces accurate estimates for the loading-carrying capacity of the shear members taken as an illustrative application by correlation with the experimental results, so the proposed approach is valid.

  3. Evaluation of Fatigue Strength Improvement by CFRP Laminates and Shot Peening onto the Tension Flanges Joining Corrugated SteelWebs

    Directory of Open Access Journals (Sweden)

    Zhi-Yu Wang

    2015-08-01

    Full Text Available Corrugated steel web with inherent high out-of-plane stiffness has a promising application in configuring large span highway bridge girders. Due to the irregularity of the configuration details, the local stress concentration poses a major fatigue problem for the welded flange plates of high strength low alloy structural steels. In this work, the methods of applying CFRP laminate and shot peening onto the surfaces of the tension flanges were employed with the purpose of improving the fatigue strength of such configuration details. The effectiveness of this method in the improvement of fatigue strength has been examined experimentally. Test results show that the shot peening significantly increases hardness and roughness in contrast to these without treatment. Also, it has beneficial effects on the fatigue strength enhancement when compared against the test data of the joints with CFRP strengthening. The stiffness degradation during the loading progress is compared with each treatment. Incorporating the stress acting on the constituent parts of the CFRP laminates, a discussion is made regarding the mechanism of the retrofit and related influencing factors such as corrosion and economic cost. This work could enhance the understanding of the CFRP and shot peening in repairing such welded details and shed light on the reinforcement design of welded joints between corrugated steel webs and flange plates.

  4. Designing A Conventional Aircraft

    OpenAIRE

    Sonei, Arash

    2014-01-01

    This paper is explaining the important design phases of dimensioning an unmanned conventional aircraft from scratch and will also design one according to a few chosen requirements. The design phases discussed will be all from wing dimensioning to stability and spin recovery, aircraft performance requirements and how to select a motor which overcomes these. As well as the optimal rate of climb for improved efficiency is discussed. In the end an aircraft which manages the set requirements and i...

  5. Lightning effects on aircraft

    Science.gov (United States)

    1977-01-01

    Direct and indirect effects of lightning on aircraft were examined in relation to aircraft design. Specific trends in design leading to more frequent lightning strikes were individually investigated. These trends included the increasing use of miniaturized, solid state components in aircraft electronics and electric power systems. A second trend studied was the increasing use of reinforced plastics and other nonconducting materials in place of aluminum skins, a practice that reduces the electromagnetic shielding furnished by a conductive skin.

  6. Development of the experimental procedure to examine the response of carbon fiber-reinforced polymer composites subjected to a high-intensity pulsed electric field and low-velocity impact

    Science.gov (United States)

    Hart, Robert J.; Zhupanska, Olesya I.

    2016-01-01

    A new fully automated experimental setup has been developed to study the response of carbon fiber reinforced polymer (CFRP) composites subjected to a high-intensity pulsed electric field and low-velocity impact. The experimental setup allows for real-time measurements of the pulsed electric current, voltage, impact load, and displacements on the CFRP composite specimens. The setup includes a new custom-built current pulse generator that utilizes a bank of capacitor modules capable of producing a 20 ms current pulse with an amplitude of up to 2500 A. The setup enabled application of the pulsed current and impact load and successfully achieved coordination between the peak of the current pulse and the peak of the impact load. A series of electrical, impact, and coordinated electrical-impact characterization tests were performed on 32-ply IM7/977-3 unidirectional CFRP composites to assess their ability to withstand application of a pulsed electric current and determine the effects of the pulsed current on the impact response. Experimental results revealed that the electrical resistance of CFRP composites decreased with an increase in the electric current magnitude. It was also found that the electrified CFRP specimens withstood higher average impact loads compared to the non-electrified specimens.

  7. Development of the experimental procedure to examine the response of carbon fiber-reinforced polymer composites subjected to a high-intensity pulsed electric field and low-velocity impact.

    Science.gov (United States)

    Hart, Robert J; Zhupanska, Olesya I

    2016-01-01

    A new fully automated experimental setup has been developed to study the response of carbon fiber reinforced polymer (CFRP) composites subjected to a high-intensity pulsed electric field and low-velocity impact. The experimental setup allows for real-time measurements of the pulsed electric current, voltage, impact load, and displacements on the CFRP composite specimens. The setup includes a new custom-built current pulse generator that utilizes a bank of capacitor modules capable of producing a 20 ms current pulse with an amplitude of up to 2500 A. The setup enabled application of the pulsed current and impact load and successfully achieved coordination between the peak of the current pulse and the peak of the impact load. A series of electrical, impact, and coordinated electrical-impact characterization tests were performed on 32-ply IM7/977-3 unidirectional CFRP composites to assess their ability to withstand application of a pulsed electric current and determine the effects of the pulsed current on the impact response. Experimental results revealed that the electrical resistance of CFRP composites decreased with an increase in the electric current magnitude. It was also found that the electrified CFRP specimens withstood higher average impact loads compared to the non-electrified specimens. PMID:26827355

  8. Inverse model for defect characterisation of externally glued CFRP on reinforced concrete structures: comparative study of square pulsed and pulsed thermography

    OpenAIRE

    CRINIERE, Antoine; Dumoulin, Jean; IBARRA CASTANEDO, Clemente; MALDAGUE, Xavier

    2014-01-01

    The objective of the study summarised, hereafter, is to compare square pulsed and pulsed thermography for defect detection and characterisation of carbon fibre-reinforced polymer (CFRP) plates used as structural reinforcement in Civil Engineering applications. For this purpose, two specimens built with cement concrete support were manufactured in the laboratory. They were reinforced with CFRP plates bonded to their surface and different artificial defects were inserted during gluing. Two type...

  9. Recycling of CFRP for high value applications: Effect of sizing removal and environmental analysis of the SuperCritical Fluid Solvolysis

    OpenAIRE

    DAUGUET, Michel; MANTAUX, Olivier; PERRY, Nicolas; ZHAO, Yaoyao Fiona

    2015-01-01

    The recycling of Carbon Fibers Reinforced Plastics (CFRP) wastes is becoming increasingly important in the aerospace industry. For most of the technologies, the recycled CF (rCF) are discontinuous, misaligned and unsized. Compared to thermal treatments, the orientation, the length and the brittleness of the rCF are better preserved with the SuperCritical Water Solvolysis (SCWS). The effect of the sizing removal on the recycled CFRP behavior is studied by conducting static characterizations. R...

  10. Composites

    OpenAIRE

    Zhao, Hanqing; Guo, Yuanzheng

    2014-01-01

    This thesis was a literature study concerning composites. With composites becoming increasingly popular in various areas such as aerospace industry and construction, the research about composites has a significant meaning accordingly. This thesis was aim at introducing some basic information of polymer matrix composites including raw mate-rial, processing, testing, applications and recycling to make a rough understanding of this kind of material for readers. Polymeric matrices, fillers,...

  11. In-flight fiber optic acoustic emission sensor (FAESense) system for the real time detection, localization, and classification of damage in composite aircraft structures

    Science.gov (United States)

    Mendoza, Edgar; Prohaska, John; Kempen, Connie; Esterkin, Yan; Sun, Sunjian

    2013-05-01

    Acoustic emission sensing is a leading structural health monitoring technique use for the early warning detection of structural damage associated with impacts, cracks, fracture, and delaminations in advanced materials. Current AE systems based on electronic PZT transducers suffer from various limitations that prevent its wide dynamic use in practical avionics and aerospace applications where weight, size and power are critical for operation. This paper describes progress towards the development of a wireless in-flight distributed fiber optic acoustic emission monitoring system (FAESense™) suitable for the onboard-unattended detection, localization, and classification of damage in avionics and aerospace structures. Fiber optic AE sensors offer significant advantages over its counterpart electronic AE sensors by using a high-density array of micron-size AE transducers distributed and multiplex over long lengths of a standard single mode optical fiber. Immediate SHM applications are found in commercial and military aircraft, helicopters, spacecraft, wind mil turbine blades, and in next generation weapon systems, as well as in the petrochemical and aerospace industries, civil structures, power utilities, and a wide spectrum of other applications.

  12. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2010-01-01

    New Year is an open composition to be realised by improvising musicians. It is included in "From the Danish Seasons" (see under this title). See more about my composition practise in the entry "Composition - General Introduction". This work is licensed under a Creative Commons "by-nc" License. You...

  13. FE ANALYSIS OF WELDED STEEL BEAM STRENGTHENED BY CFRP%CFRP加固焊接工字钢梁的有限元分析

    Institute of Scientific and Technical Information of China (English)

    赵芳琴; 牛忠荣; 鲁栋; 闫艳

    2009-01-01

    碳纤维增强复合材料(CFRP)加固混凝土结构目前已经得到广泛应用,但在钢结构加回方面应用尚少.通过有限元软件ANSYS对碳纤维布和碳纤维板加固焊接工字钢梁进行变形和应力场分析,得出CFRP片材加固可增强钢梁的刚度,降低钢梁的最大应力.该分析结果可用于钢梁疲劳寿命分析.%A significant number of concrete members were strengthened by carbon fiber reinforced polymer (CFRP). However there are only a few applications in strengthening steel structure with CFRP. In this paper, the influences of CFRP plates and sheets in strengthening steel structure are studied with finite element method (FEM).The computed results show that the CFRP enhance the rigidity and reduce the maximum stress of welded steel beams. The present results can be used to evaluate the fatigue life of welded 1-beam strengthened with CFRP.

  14. NONLINEAR ANALYSIS OF CFRP- PRESTRESSED CONCRETE BEAMS SUBJECTED TO INCREMENTAL STATIC LOADING BY FINITE ELEMENTS

    Directory of Open Access Journals (Sweden)

    Husain M. Husain

    2013-05-01

    Full Text Available In this work a program is developed to carry out the nonlinear analysis (material nonlinearity of prestressed concrete beams using tendons of carbon fiber reinforced polymer (CFRP instead of steel. The properties of this material include high strength, light weight, and insusceptibility to corrosion and magnetism. This material is still under investigation, therefore it needs continuous work to make it beneficial in concrete design. Four beams which are tested experimentally by Yan et al. are examined by the developed computer program to reach a certain analytical approach of the design and analysis of such beams because there is no available restrictions or recommendations covering this material in the codes. The program uses the finite element analysis by dividing the beams into isoparametric 20-noded brick elements. The results obtained are good in comparison with experimental results.

  15. Failure Load Test of a CFRP Strengthened Railway Bridge in Oumlrnskoumlldsvik, Sweden

    DEFF Research Database (Denmark)

    Täljsten, Björn; Bergström, Markus; Carolin, Anders

    2009-01-01

    The results obtained when performing a load test to failure of an existing structure are valuable when assessing calculation models, updating finite element models, and investigating the true structural behavior. In this paper a destructive testing and monitoring of a railway bridge in Örnsköldsvik...... using carbon fiber reinforced polymer (CFRP) rectangular rods epoxy bonded in sawed up slots, e.g., near surface mounted reinforcement. The strengthening was very successful and resulted in a desired shear failure when the bridge was loaded to failure. The load-carrying capacity in bending...... for the unstrengthened and strengthened bridge as well as the shear capacity was predicted with Monte Carlo simulations. The particular calculation presented showed that there was a 25% probability of a bending failure instead of a shear failure. Monitoring showed that the strengthening reduced the strain in the tensile...

  16. Technology for aircraft energy efficiency

    Science.gov (United States)

    Klineberg, J. M.

    1977-01-01

    Six technology programs for reducing fuel use in U.S. commercial aviation are discussed. The six NASA programs are divided into three groups: Propulsion - engine component improvement, energy efficient engine, advanced turboprops; Aerodynamics - energy efficient transport, laminar flow control; and Structures - composite primary structures. Schedules, phases, and applications of these programs are considered, and it is suggested that program results will be applied to current transport derivatives in the early 1980s and to all-new aircraft of the late 1980s and early 1990s.

  17. Structural ballistic armour for transport aircraft

    OpenAIRE

    Horsfall, I; Austin, S J; Bishop, W.

    2000-01-01

    This paper describes the structural response of a current ceramic-faced composite armour system and a proposed structural armour system for aircraft use. The proposed structural ballistic armour system is shown to be capable of providing significant structural integrity even after ballistic impact whilst providing ballistic protection equivalent to an existing applique system. The addition of a carbon fibre reinforced plastic front panel to the existing ceramic faced composite armour system i...

  18. Cable Tensiometer for Aircraft

    Science.gov (United States)

    Nunnelee, Mark (Inventor)

    2008-01-01

    The invention is a cable tensiometer that can be used on aircraft for real-time, in-flight cable tension measurements. The invention can be used on any aircraft cables with high precision. The invention is extremely light-weight, hangs on the cable being tested and uses a dual bending beam design with a high mill-volt output to determine tension.

  19. Flexural strengthening of RC beams using hybrid composite plate (HCP): experimental and analytical study

    OpenAIRE

    Esmaeeli, Esmaeel; Barros, Joaquim A. O.

    2015-01-01

    Hybrid Composite Plate (HCP) is a reliable recently proposed retrofitting solution for concrete structures, which is composed of a strain hardening cementitious composite (SHCC) plate reinforced with Carbon Fibre Reinforced Polymer (CFRP). This system benefits from the synergetic advantages of these two composites, namely the high ductility of SHCC and the high tensile strength of CFRPs. In the materialstructural of HCP, the ultra-ductile SHCC plate acts as a suitable medium for s...

  20. Crack propagation and arrest in CFRP materials with strain softening regions

    Science.gov (United States)

    Dilligan, Matthew Anthony

    Understanding the growth and arrest of cracks in composite materials is critical for their effective utilization in fatigue-sensitive and damage susceptible applications such as primary aircraft structures. Local tailoring of the laminate stack to provide crack arrest capacity intermediate to major structural components has been investigated and demonstrated since some of the earliest efforts in composite aerostructural design, but to date no rigorous model of the crack arrest mechanism has been developed to allow effective sizing of these features. To address this shortcoming, the previous work in the field is reviewed, with particular attention to the analysis methodologies proposed for similar arrest features. The damage and arrest processes active in such features are investigated, and various models of these processes are discussed and evaluated. Governing equations are derived based on a proposed mechanistic model of the crack arrest process. The derived governing equations are implemented in a numerical model, and a series of simulations are performed to ascertain the general characteristics of the proposed model and allow qualitative comparison to existing experimental results. The sensitivity of the model and the arrest process to various parameters is investigated, and preliminary conclusions regarding the optimal feature configuration are developed. To address deficiencies in the available material and experimental data, a series of coupon tests are developed and conducted covering a range of arrest zone configurations. Test results are discussed and analyzed, with a particular focus on identification of the proposed failure and arrest mechanisms. Utilizing the experimentally derived material properties, the tests are reproduced with both the developed numerical tool as well as a FEA-based implementation of the arrest model. Correlation between the simulated and experimental results is analyzed, and future avenues of investigation are identified

  1. Aircraft operations management manual

    Science.gov (United States)

    1992-01-01

    The NASA aircraft operations program is a multifaceted, highly diverse entity that directly supports the agency mission in aeronautical research and development, space science and applications, space flight, astronaut readiness training, and related activities through research and development, program support, and mission management aircraft operations flights. Users of the program are interagency, inter-government, international, and the business community. This manual provides guidelines to establish policy for the management of NASA aircraft resources, aircraft operations, and related matters. This policy is an integral part of and must be followed when establishing field installation policy and procedures covering the management of NASA aircraft operations. Each operating location will develop appropriate local procedures that conform with the requirements of this handbook. This manual should be used in conjunction with other governing instructions, handbooks, and manuals.

  2. Analysis of Influence of CFRP Embeded Length on Bending Performance of RC Beams Strengthened with Near Surface Mounted CFRP Strips%CFRP嵌条长度对加固RC梁抗弯性能影响的分析

    Institute of Scientific and Technical Information of China (English)

    唐忠亮; 陆洲导; 余江滔; 刘媛

    2012-01-01

    The near surfaced mounted ( NSM) method of CFRP strips is a new effective method used to strengthen structural components. Based on the tests carried on 5 beams strengthened with the NSM method, this paper investigates the effect of CFRP embeded length on failure modes and the ultimate bearing capacity of strengthened RC beams with the help of ABAQUS. The comparing results show that the ABAQUS can simulate accurately the failure mode, ultimate bearing capacity,concrete strain of the actual RC beams. From the simulation , It is also found that CFRP strips can maintain useful in preventing the growing of deflection after steel yielding with the increasing of CFRP strips' length.%内嵌CFRP板条加固钢筋混凝土梁在结构加固中是一种新兴的、经济有效的方法.以5根CFRP嵌入法加固RC梁的抗弯性能试验为依据,采用ABAQUS有限元分析软件模拟嵌帖长度对RC梁破坏模式及承载能力的影响.模拟结果在构件破坏模式、承载力、混凝土应变等指标上均与试验结果能较好吻合,且由模拟结果能够看出,随着嵌条长度的增大,CFRP的贡献会持续存在,钢筋屈服后挠度增大的情况得以改善.

  3. Surface Acoustic Wave Vibration Sensors for Measuring Aircraft Flutter

    Science.gov (United States)

    Wilson, William C.; Moore, Jason P.; Juarez, Peter D.

    2016-01-01

    Under NASA's Advanced Air Vehicles Program the Advanced Air Transport Technology (AATT) Project is investigating flutter effects on aeroelastic wings. To support that work a new method for measuring vibrations due to flutter has been developed. The method employs low power Surface Acoustic Wave (SAW) sensors. To demonstrate the ability of the SAW sensor to detect flutter vibrations the sensors were attached to a Carbon fiber-reinforced polymer (CFRP) composite panel which was vibrated at six frequencies from 1Hz to 50Hz. The SAW data was compared to accelerometer data and was found to resemble sine waves and match each other closely. The SAW module design and results from the tests are presented here.

  4. Program for establishing long-time flight service performance of composite materials in the center wing structure of C-130 aircraft. Phase 4: Ground/flight acceptance tests

    Science.gov (United States)

    Harvill, W. E.; Kizer, J. A.

    1976-01-01

    The advantageous structural uses of advanced filamentary composites are demonstrated by design, fabrication, and test of three boron-epoxy reinforced C-130 center wing boxes. The advanced development work necessary to support detailed design of a composite reinforced C-130 center wing box was conducted. Activities included the development of a basis for structural design, selection and verification of materials and processes, manufacturing and tooling development, and fabrication and test of full-scale portions of the center wing box. Detailed design drawings, and necessary analytical structural substantiation including static strength, fatigue endurance, flutter, and weight analyses are considered. Some additional component testing was conducted to verify the design for panel buckling, and to evaluate specific local design areas. Development of the cool tool restraint concept was completed, and bonding capabilities were evaluated using full-length skin panel and stringer specimens.

  5. Strength Analysis of Sandwitch Panels with CFRP Quasi Isotropic Layup or Isotropic Material Facesheets in Dynamic Environment Using MSC Nastran and SineMOS

    Science.gov (United States)

    Di Carlo, A.; Carbonell Garcia, A.

    2012-07-01

    The frequency response solution (SOL 111) of MSC Nastran versions prior to 2012 only allows the output of element stress components and element forces and does not allow the calculation of composite failure indices or Von-Mises stress for metallic parts. The analysis of a sandwich panel comprises several strength verifications, such as the check of facesheet and core failure as well as the check of facesheet and core local stability (shear crimping, wrinkling). In static analysis (SOL 101), MSC Nastran provides failure index output which can be used to generate fringe plots of Margins of Safety (MoS) in any post- processing tool. The other verifications (core strength and local stability) must be performed using different tools. For the dynamic analysis of sandwich panels, an analysis technique based on element forces and on failure envelope at laminate level has been developed and implemented in a Fortran program (SineMOS) which allows evaluating facesheet and core failure as well as local stability, taking into account modulus and phase information of the element forces. SineMOS is able to produce files containing information used to generate plots of minimum Margin of Safety in Patran for each failure mode. This paper shows the various steps of the analysis process, starting from the building of the failure envelope for the CFRP facesheet laminate. Finally some validation example is shown, comparing SineMOS results with results based on the application of static displacements to the nodes of the model.

  6. Application of a novel optical fiber sensor to detection of acoustic emissions by various damages in CFRP laminates

    Science.gov (United States)

    Wu, Qi; Yu, Fengming; Okabe, Yoji; Kobayashi, Satoshi

    2015-01-01

    In this research, we applied a novel optical fiber sensor, phase-shifted fiber Bragg grating balanced sensor with high sensitivity and broad bandwidth, to acoustic emission (AE) detection in carbon fiber reinforced plastics (CFRPs). AE signals generated in the tensile testing of angle-ply and cross-ply CFRP laminates were both detected by the novel optical fiber sensor and traditional PZT sensors. The cumulative hits detected by both sensors coincided after applying simple data processing to eliminate the noise, and clearly exhibited Kaiser effect and Felicity effect. Typical AE signals detected by both sensors were discussed and were tried to relate to micro CFRP damages observed via microscope. These results demonstrate that this novel optical fiber sensor can reliably detect AE signals from various damages. It has the potential to be used in practical AE detection, as an alternative to the piezoelectric PZT sensor.

  7. Application of a novel optical fiber sensor to detection of acoustic emissions by various damages in CFRP laminates

    International Nuclear Information System (INIS)

    In this research, we applied a novel optical fiber sensor, phase-shifted fiber Bragg grating balanced sensor with high sensitivity and broad bandwidth, to acoustic emission (AE) detection in carbon fiber reinforced plastics (CFRPs). AE signals generated in the tensile testing of angle-ply and cross-ply CFRP laminates were both detected by the novel optical fiber sensor and traditional PZT sensors. The cumulative hits detected by both sensors coincided after applying simple data processing to eliminate the noise, and clearly exhibited Kaiser effect and Felicity effect. Typical AE signals detected by both sensors were discussed and were tried to relate to micro CFRP damages observed via microscope. These results demonstrate that this novel optical fiber sensor can reliably detect AE signals from various damages. It has the potential to be used in practical AE detection, as an alternative to the piezoelectric PZT sensor. (paper)

  8. Ensayos de resistencia de pórticos de concreto a escala, reforzados con CFRP en los nudos

    Directory of Open Access Journals (Sweden)

    Andrés Duque

    2011-06-01

    Full Text Available The results of an experimental study of four scale concrete frames (1:2 subjected to monotonic load are presented. The four frames were designed and constructed without confinement zones in the joints and considering only the gravitational load. Two of the four concrete frames of concrete were reinforced in the joints with a confinement with polymers reinforced with carbon fiber (CFRP. The instrumentation of the tests consisted of a load cell, analogous deformimeters and strain gages in the reinforcement steel bars and in the carbonfibers. According to the experimental results, the reinforcement with fibers duplicates the resistance and the rigidity of the frames and increases its total displacement without loss of resistance in 60%.Also the confinement of the joints with CFRP diminishes remarkably the fissures and the cracks of the structural elements.

  9. Advanced materials for aircraft engine applications.

    Science.gov (United States)

    Backman, D G; Williams, J C

    1992-02-28

    A review of advances for aircraft engine structural materials and processes is presented. Improved materials, such as superalloys, and the processes for making turbine disks and blades have had a major impact on the capability of modern gas turbine engines. New structural materials, notably composites and intermetallic materials, are emerging that will eventually further enhance engine performance, reduce engine weight, and thereby enable new aircraft systems. In the future, successful aerospace manufacturers will combine product design and materials excellence with improved manufacturing methods to increase production efficiency, enhance product quality, and decrease the engine development cycle time.

  10. Titanium alloys Russian aircraft and aerospace applications

    CERN Document Server

    Moiseyev, Valentin N

    2005-01-01

    This text offers previously elusive information on state-of-the-art Russian metallurgic technology of titanium alloys. It details their physical, mechanical, and technological properties, as well as treatments and applications in various branches of modern industry, particularly aircraft and aerospace construction. Titanium Alloys: Russian Aircraft and Aerospace Applications addresses all facets of titanium alloys in aerospace and aviation technology, including specific applications, fundamentals, composition, and properties of commercial alloys. It is useful for all students and researchers interested in the investigation and applications of titanium.

  11. Efficient processing of CFRP with a picosecond laser with up to 1.4 kW average power

    Science.gov (United States)

    Onuseit, V.; Freitag, C.; Wiedenmann, M.; Weber, R.; Negel, J.-P.; Löscher, A.; Abdou Ahmed, M.; Graf, T.

    2015-03-01

    Laser processing of carbon fiber reinforce plastic (CFRP) is a very promising method to solve a lot of the challenges for large-volume production of lightweight constructions in automotive and airplane industries. However, the laser process is actual limited by two main issues. First the quality might be reduced due to thermal damage and second the high process energy needed for sublimation of the carbon fibers requires laser sources with high average power for productive processing. To achieve thermal damage of the CFRP of less than 10μm intensities above 108 W/cm² are needed. To reach these high intensities in the processing area ultra-short pulse laser systems are favored. Unfortunately the average power of commercially available laser systems is up to now in the range of several tens to a few hundred Watt. To sublimate the carbon fibers a large volume specific enthalpy of 85 J/mm³ is necessary. This means for example that cutting of 2 mm thick material with a kerf width of 0.2 mm with industry-typical 100 mm/sec requires several kilowatts of average power. At the IFSW a thin-disk multipass amplifier yielding a maximum average output power of 1100 W (300 kHz, 8 ps, 3.7 mJ) allowed for the first time to process CFRP at this average power and pulse energy level with picosecond pulse duration. With this unique laser system cutting of CFRP with a thickness of 2 mm an effective average cutting speed of 150 mm/sec with a thermal damage below 10μm was demonstrated.

  12. Ensayos de resistencia de pórticos de concreto a escala, reforzados con CFRP en los nudos

    OpenAIRE

    Andrés Duque; Ingrid Amazo; Daniel Ruiz

    2011-01-01

    The results of an experimental study of four scale concrete frames (1:2) subjected to monotonic load are presented. The four frames were designed and constructed without confinement zones in the joints and considering only the gravitational load. Two of the four concrete frames of concrete were reinforced in the joints with a confinement with polymers reinforced with carbon fiber (CFRP). The instrumentation of the tests consisted of a load cell, analogous deformimeters and strain gages in the...

  13. 0.4-1.2 GHz hybrid Al-CFRP open-boundary quad-ridge horn

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Pivnenko, Sergey; Breinbjerg, Olav

    2011-01-01

    We present a 0.4-1.2 GHz open-boundary quad-ridge horn to be used as a wide-band probe at the DTU-ESA Spherical Near-Field Antenna Test Facility at the Technical University of Denmark (DTU). Due to adopted hybrid Al-CFRP fabrication technology, the weight of the probe is reduced by a factor of 2...

  14. Flame Retardancy Effects of Graphene Nanoplatelet/Carbon Nanotube Hybrid Membranes on Carbon Fiber Reinforced Epoxy Composites

    Directory of Open Access Journals (Sweden)

    Dongxian Zhuo

    2013-01-01

    Full Text Available Carbon nanotube/graphene nanoplatelet (MWCNT/GNP hybrid membranes with lower liquid permeability and better barrier effect compared to MWCNT membranes were successfully synthesized by vacuum filtering. Their morphologies, water permeability, and pore structures were characterized by a scanning electron microscope (SEM and nitrogen adsorption isotherms. Furthermore, MWCNT/GNP membranes were used to improve the flame retardancy of carbon fiber reinforced polymer (CFRP composites, and the influence of weight percentage of GNPs on the permeability and flame retardancy of MWCNT/GNP membranes was systematically investigated. Results show that incorporation of MWCNT/GNP membranes on CFRP composite plates can remarkably improve the flame retardancy of CFRP composites. Specifically, the incorporation of hierarchical MWCNT/GNP membrane with 7.5 wt% of GNP displays a 35% reduction in the peak heat release rate (PHRR for a CFRP composite plate with the epoxy as matrix and a 11% reduction in PHRR compared with the incorporation of MWCNT membrane only. A synergistic flame retarding mechanism is suggested to be attributed to these results, which includes controlling the pore size and penetrative network structure.

  15. Program for establishing long-time flight service performance of composite materials in the center wing structure of C-130 aircraft. Phase 1: Advanced development

    Science.gov (United States)

    Harvill, W. E.; Kays, A. O.; Young, E. C.; Mcgee, W. M.

    1972-01-01

    Areas where selective reinforcement of conventional metallic structure can improve static strength/fatigue endurance at lower weight than would be possible if metal reinforcement were used are discussed. These advantages are now being demonstrated by design, fabrication, and tests of three boron-epoxy reinforced C-130E center wing boxes. This structural component was previously redesigned using an aluminum build-up to meet increased severity of fatigue loadings. Direct comparisons of relative structural weights, manufacturing costs, and producibility can therefore be obtained, and the long-time flight service performance of the composite reinforced structure can be evaluated against the wide background of metal reinforced structure.

  16. Scanning tone burst eddy-current thermography (S-TBET) for NDT of carbon fiber reinforced plastic (CFRP) components

    Science.gov (United States)

    Libin, M. N.; Maxfield, B. W.; Balasubramanian, Krishnan

    2014-02-01

    Tone Burst Eddy Current technique uses eddy current to apply transient heating inside a component and uses a conventional IR camera for visualization of the response to the transient heating. This technique has been earliest demonstrated for metallic components made of AL, Steel, Stainless Steel, etc., and for detection of cracks, corrosion and adhesive dis-bonds. Although, not nearly as conducting as metals, the Carbon Fibre Reinforced Plastic (CFRP) material absorbs measurable electromagnetic radiation in the frequency range above 10 kHz. When the surface temperature is observed on the surface that is being heated (defined as the surface just beneath and slightly to one side of the heating coil), the surface temperature increases with increasing frequency because the internal heating increases with frequency. A 2-D anisotropic transient Eddy current heating and thermal conduction model has been developed that provides a reasonable description of the processes described above. The inherent anisotropy of CFRP laminates is included in this model by calculating the heating due to three superimposed, tightly coupled isotropic layers having a specified ply-layup. The experimental apparatus consists of an induction heating coil and an IR camera with low NETD and high frame rates. The coil is moved over the sample using a stepper motor controlled manipulator. The IR data recording is synchronized with the motion control to provide a movie of the surface temperature over time. Several components were evaluated for detection of impact damage, location of stiffeners, etc. on CFRP components.

  17. Scanning tone burst eddy-current thermography (S-TBET) for NDT of carbon fiber reinforced plastic (CFRP) components

    Energy Technology Data Exchange (ETDEWEB)

    Libin, M. N.; Maxfield, B. W.; Balasubramanian, Krishnan [Centre for Nondestructive Evaluation, Indian Institute of Technology Madras, Chennai 600036 (India)

    2014-02-18

    Tone Burst Eddy Current technique uses eddy current to apply transient heating inside a component and uses a conventional IR camera for visualization of the response to the transient heating. This technique has been earliest demonstrated for metallic components made of AL, Steel, Stainless Steel, etc., and for detection of cracks, corrosion and adhesive dis-bonds. Although, not nearly as conducting as metals, the Carbon Fibre Reinforced Plastic (CFRP) material absorbs measurable electromagnetic radiation in the frequency range above 10 kHz. When the surface temperature is observed on the surface that is being heated (defined as the surface just beneath and slightly to one side of the heating coil), the surface temperature increases with increasing frequency because the internal heating increases with frequency. A 2-D anisotropic transient Eddy current heating and thermal conduction model has been developed that provides a reasonable description of the processes described above. The inherent anisotropy of CFRP laminates is included in this model by calculating the heating due to three superimposed, tightly coupled isotropic layers having a specified ply-layup. The experimental apparatus consists of an induction heating coil and an IR camera with low NETD and high frame rates. The coil is moved over the sample using a stepper motor controlled manipulator. The IR data recording is synchronized with the motion control to provide a movie of the surface temperature over time. Several components were evaluated for detection of impact damage, location of stiffeners, etc. on CFRP components.

  18. Assessment of alternative joining techniques for Ti–6Al–4V/CFRP hybrid joints regarding tensile and fatigue strength

    International Nuclear Information System (INIS)

    Highlights: • Nd:YAG laser riveting of Ti–6Al–4V/CFRP lap joint was successfully realized. • Tensile strength is comparable to that of conventional riveted lap joints. • Fatigue strength of conventional riveted joint can be increased by adhesive bonding. • The effect of adhesive bonding is comparable to surface structuring of Ti–6Al–4V. - Abstract: CFRP and titanium joints are used in the aerospace industry. These materials are usually joined by titanium rivets which are inserted into holes drilled through both materials. Conventional riveted hybrid joints of CFRP and titanium parts fail under quasi static loading due to the uneven load distribution at the titanium rivets. Under cyclic loading, the fatigue failure occurs mainly in the titanium part because of the higher notch sensitivity. The aim of this work is the comparison of different joining concepts in terms of stiffness, strength and fatigue limit. First, laser riveting, here titanium pins are Nd:YAG laser beam welded to the Ti–6Al–4V parts. Second, conventional riveted hybrid joint is combined with adhesive bonding. Third, surface structuring of the Ti–6Al–4V parts is used to enhance friction in the riveted joint. Tensile and fatigue tests as well as fractographical examinations are performed to establish the process–property–performance relationship of the hybrid joints. Laser riveting leads to higher stiffness but equal strength, when compared to conventional riveted joints. Fatigue life is improved by the implementation of adhesive bonding and surface structuring

  19. Strengthening of RC Beams with Large Openings in Shear by CFRP Laminates: Experiment and 2D Nonlinear Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    S.C. Chin

    2012-05-01

    Full Text Available This study presents the experimental study and numerical analysis of Reinforced Concrete (RC beams with large square openings placed in the shear region, at a distance 0.5d and d away from the support, strengthened by Carbon Fiber Reinforced Polymer (CFRP laminates. This research aims to investigate the strength losses in RC beam due to the presence of large square openings placed at two different locations in shear region. Also, in order to re-gain the beam structural capacity loss due to the openings, strengthening by CFRP laminates around the openings were studied. A total of six RC beams were tested to failure under four point loading including control beams, un-strengthened and strengthened RC beams with large square openings in shear region at a distance 0.5d and d away from the support. The CFRP strengthening configuration considered in this study was a full wrapping system around the square openings. A nonlinear finite element program, ATENA was used to validate the results of the tested beams. Comparisons between the finite element predictions and experimental results in terms of crack patterns and load deflection relationships are presented. The crack pattern results of the finite element model show good agreement with the experimental data. The load midspan deflection curves of the finite element models exhibited a stiffer result compared to the experimental beams. The possible reason may be due to the perfect bond assumption between the concrete and steel reinforcement.

  20. SOLAR AIRCRAFT DESIGN

    OpenAIRE

    RAHMATI, Sadegh; GHASED, Amir

    2015-01-01

    Abstract. Generally domain Aircraft uses conventional fuel. These fuel having limited life, high cost and pollutant. Also nowadays price of petrol and other fuels are going to be higher, because of scarcity of those fuels. So there is great demand of use of non-exhaustible unlimited source of energy like solar energy. Solar aircraft is one of the ways to utilize solar energy. Solar aircraft uses solar panel to collect the solar radiation for immediate use but it also store the remaining part ...

  1. Aircraft Fire Protection Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Navy Aircraft Protection Laboratory provides complete test support for all Navy air vehicle fire protection systems. The facility allows for the simulation of a...

  2. Solar thermal aircraft

    Science.gov (United States)

    Bennett, Charles L.

    2007-09-18

    A solar thermal powered aircraft powered by heat energy from the sun. A heat engine, such as a Stirling engine, is carried by the aircraft body for producing power for a propulsion mechanism, such as a propeller. The heat engine has a thermal battery in thermal contact with it so that heat is supplied from the thermal battery. A solar concentrator, such as reflective parabolic trough, is movably connected to an optically transparent section of the aircraft body for receiving and concentrating solar energy from within the aircraft. Concentrated solar energy is collected by a heat collection and transport conduit, and heat transported to the thermal battery. A solar tracker includes a heliostat for determining optimal alignment with the sun, and a drive motor actuating the solar concentrator into optimal alignment with the sun based on a determination by the heliostat.

  3. Depreciation of aircraft

    Science.gov (United States)

    Warner, Edward P

    1922-01-01

    There is a widespread, and quite erroneous, impression to the effect that aircraft are essentially fragile and deteriorate with great rapidity when in service, so that the depreciation charges to be allowed on commercial or private operation are necessarily high.

  4. Aircraft electromagnetic compatibility

    Science.gov (United States)

    Clarke, Clifton A.; Larsen, William E.

    1987-01-01

    Illustrated are aircraft architecture, electromagnetic interference environments, electromagnetic compatibility protection techniques, program specifications, tasks, and verification and validation procedures. The environment of 400 Hz power, electrical transients, and radio frequency fields are portrayed and related to thresholds of avionics electronics. Five layers of protection for avionics are defined. Recognition is given to some present day electromagnetic compatibility weaknesses and issues which serve to reemphasize the importance of EMC verification of equipment and parts, and their ultimate EMC validation on the aircraft. Proven standards of grounding, bonding, shielding, wiring, and packaging are laid out to help provide a foundation for a comprehensive approach to successful future aircraft design and an understanding of cost effective EMC in an aircraft setting.

  5. Aircraft Data Acquisition

    Directory of Open Access Journals (Sweden)

    Elena BALMUS

    2016-03-01

    Full Text Available The introduction of digital systems instead of analog ones has created a major separation in the aviation technology. Although the digital equipment made possible that the increasingly faster controllers take over, we should say that the real world remains essentially analogue [4]. Fly-by-wire designers attempting to control and measure the real feedback of an aircraft were forced to find a way to connect the analogue environment to their digital equipment. In order to manage the implications of this division in aviation, data optimization and comparison has been quite an important task. The interest in using data acquisition boards is being driven by the technology and design standards in the new generation of aircraft and the ongoing efforts of reducing weight and, in some cases addressing the safety risks. This paper presents a sum of technical report data from post processing and diversification of data acquisition from Arinc 429 interface on a research aircraft platform. Arinc 429 is by far the most common data bus in use on civil transport aircraft, regional jets and executive business jets today. Since its introduction on the Boeing 757/767 and Airbus aircraft in the early 1980s hardly any aircraft has been produced without the use of this data bus. It was used widely by the air transport indu

  6. Scarf Repair of Composite Laminates

    Directory of Open Access Journals (Sweden)

    Xie Zonghong

    2016-01-01

    Full Text Available The use of composite materials, such as carbon-fiber reinforced plastic (CFRP composites, aero-structures has led to an increased need of advanced assembly joining and repair technologies. Adhesive bonded repairs as an alternative to recover full or part of initial strength were investigated. Tests were conducted with the objective of evaluating the effectiveness of techniques used for repairing damage fiber reinforced laminated composites. Failure loads and failure modes were generated and compared with the following parameters: scarf angles, roughness of grind tool and number of external plies. Results showed that scarf angle was the critical parameter and the largest tensile strength was observed with the smallest scarf angle. Besides, the use of external plies at the outer surface could not increase the repairs efficiency for large scarf angle. Preparing the repair surfaces by sanding them with a sander ranging from 60 to 100 grit number had significant effect on the failure load. These results allowed the proposal of design principles for repairing CFRP structures.

  7. CFRP加固旧木柱性能的试验研究%Experimental Research on CFRP-Strengthened Old Timber Columns

    Institute of Scientific and Technical Information of China (English)

    李向民; 许清风; 朱雷; 卢永锋; 汤瑞忠

    2009-01-01

    Eight old timber columns strengthened with CFRP strips are tested in the paper and effective factors such as layout and layer of CFRP strips are studied. The ultimate load-bearing capacities of old timber columns reinforced with CFRP have 9.2%~26.6% increases over the control specimen, and the ductility performance also has a significant betterment. The ultimate load-bearing capacities of old timber column strengthened with angle steel and confined by CFRP strip has 68.0% increases over the control specimen. Strengthened old timber column with CFRP is an effective method, and it can be used for strengthening timber structures.%通过8根CFRP加固旧木柱的试验,重点研究了CFRP形式、层数对加固旧木柱受力性能的影响.研究结果表明,粘贴CFRP布加固的旧木柱受压承载力提高9.2%~26.6%,延性性能也得到明显改善.采用角钢加固并用CFRP包裹后木柱的受压承载力提高68.0%.CFRP加固旧木柱能显著提高其受压承载力和延性,可应用于木结构维修加固的工程实践.

  8. CFRP布加固圆形木梁抗弯性能的试验%Experimental of Bending Behavior of Circular Timber Beams Strengthened with CFRP Sheets

    Institute of Scientific and Technical Information of China (English)

    欧阳煜; 李游

    2012-01-01

    In practice, most wood beams to be repaired have already been damaged or degraded. It is necessary to study the structural performances of damaged wood beams reinforced by carbon fiber reinforced polymer (CFRP) sheets. Based on static tests of 8 damaged circular timber beams strengthened with CFRP sheets, bending behaviors are studied, including failure characteristics, ultimate bearing capacity, rigidity, and strain of timber section. The results show that CFRP sheets have a good strengthening effect for timber beams. The loading capacity of a timber beam reinforced by CFRP is effectively enhanced. The results are useful to practical design.%对在实际工程中已经受损的木梁加固后的结构性能进行研究.通过对8根圆形木梁进行静力试验,研究碳纤维增强复合材料(carbon fiber reinforced polymer,CFRP)布加固受损木梁的抗弯性能,包括破坏特性、极限荷载、刚度、截面应变等结构性能.试验结果表明,CFRP布加固受损木梁具有良好的效果,能够有效提高木梁的承载力和刚度.研究结论对碳纤维工程加固的应用具有一定的参考价值.

  9. Bonded structure application for aircraft. Kokuki ni okeru secchaku gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, O. (Japan Airlines Co. Ltd., Tokyo (Japan))

    1991-01-05

    Adhesives play an important role in a technology of the aircraft structure for which lightness and strength are required. The paper explains the present situation of bonding technology employed for aircraft, the honeycomb structure, production of composite materials and the related problems. Advantages and purposes of employing adhesives as substitutes for fasteners like screws, rivets, etc. are as follows: decreases in stress concentration, weight reduction, smoothing of surfaces, improvement of acoustic fatigue by adhesives flexibility, prevention of gas-liquid leakage. Epoxide adhesives are mainly used for aircraft. Together with tear straps, which are metal-metal bonded to the rear fuselage plate of aircraft, and waffle doublers, an aluminium honeycomb sandwich structure, whose weight is 1/7 of an aluminium plate same in rigidity, is used in such parts of aircraft as spoilers, outer plates of flaps, etc. The problem of the bonded structure is detachment. Therefore, how to prevent, discover and repair it is most important. 3 figs.

  10. Reusing recycled fibers in high-value fiber-reinforced polymer composites: Improving bending strength by surface cleaning

    OpenAIRE

    SHI, JIAN; Bao, Limin; Kobayashi, Ryouhei; Kato, Jun; Kemmochi, Kiyoshi

    2012-01-01

    Glass fiber-reinforced polymer (GFRP) composites and carbon fiber-reinforced polymer (CFRP) composites were recycled using superheated steam. Recycled glass fibers (R-GFs) and recycled carbon fibers (R-CFs) were surface treated for reuse as fiber-reinforced polymer (FRP) composites. Treated R-GFs (TR-GFs) and treated R-CFs (TR-CFs) were characterized by scanning electron microscopy (SEM) and remanufactured by vacuum-assisted resin transfer molding (VARTM). Most residual resin impurities were ...

  11. Fine aerosol bulk composition measured on WP-3D research aircraft in vicinity of the Northeastern United States – results from NEAQS

    Directory of Open Access Journals (Sweden)

    C. Warneke

    2007-02-01

    Full Text Available During the New England Air Quality Study (NEAQS in the summer of 2004, airborne measurements were made of the major inorganic ions and the water-soluble organic carbon (WSOC of the submicron (PM1.0 aerosol. These and ancillary data are used to describe the overall aerosol chemical characteristics encountered during the study. Fine particle mass was estimated from particle volume and a calculated density based on measured particle composition. Fine particle organic matter (OM was estimated from WSOC and a mass balance analysis. The aerosol over the northeastern United States (U.S. and Canada was predominately sulfate and associated ammonium, and organic components, although in unique plumes additional ionic components were also periodically above detection limits. In power generation regions, and especially in the Ohio River Valley region, the aerosol tended to be predominantly sulfate (~60% μg μg−1 and apparently acidic, based on an excess of measured anions compared to cations. In all other regions where sulfate concentrations were lower and a smaller fraction of overall mass, the cations and anions were balanced suggesting a more neutral aerosol. In contrast, the WSOC and estimated OM were more spatially uniform and the fraction of OM relative to PM mass largely influenced by sources of sulfate. The study median OM mass fraction was 40%. Throughout the study region, sulfate and organic aerosol mass were highest near the surface and decreased rapidly with increasing altitude. The relative fraction of organic mass to sulfate was similar within the boundary layer (altitude less than ~2.5 km, but was significantly higher in the free troposphere (above ~2.5 km. A number of distinct biomass burning plumes from fires in Alaska and the Yukon were periodically intercepted, mostly at altitudes between 3 and 4 km. These plumes were associated with highest aerosol concentrations of the study and were largely comprised of organic aerosol components

  12. Electrical Resistance and Acoustic Emission Measurements for Monitoring the Structural Behavior of CFRP Laminate

    KAUST Repository

    Zhou, Wei

    2015-07-12

    Electrical resistance and acoustic emission (AE) measurement are jointly used to monitor the degradation in CFRP laminates subjected to tensile tests. The objective of this thesis is to perform a synergertic analysis between a passive and an active methods to better access how these perform when used for Structural Health Moni- toring (SHM). Laminates with three different stacking sequences: [0]4, [02/902]s and [+45/ − 45]2s are subjected to monotonic and cyclic tensile tests. In each laminate, we carefully investigate which mechanisms of degradation can or cannot be detect- ed by each technique. It is shown that most often, that acoustic emission signals start before any electrical detection is possible. This is is explained based on the redundance of the electrical network that makes it less sensitive to localized damages. Based on in depth study of AE signals clustering, a new classification is proposed to recognize the different damage mechanims based on only two parameters: the RA (rise time/amplitude) and the duration of the signal.

  13. Radiation resistance of GFRP and CFRP using bisphenol A system epoxy as matrix

    International Nuclear Information System (INIS)

    The use of fiber-reinforced plastics as structural materials is increasing, but they are apt to be affected by the environment of their use unlike metals. When FRPs are used as the material requiring endurance, the resin composing the FRPs deteriorates due to radiation, and it causes the lowering of the characteristics of the FRPs. Accordingly, it is very important to evaluate the radiation resistance of FRPs and to understand the mechanism of deterioration. In this study, the deterioration due to electron beam irradiation and its mechanism of glass fiber reinforced plastics (GFRP) and carbon fiber reinforced plastics (CFRP) using bisphenol A system epoxy as the matrix were evaluated by bending strength test, rate of boiling water absorption test and scanning acoustic microscope observation, and the radiation resistance based on the difference of fiber materials was examined. The samples, the irradiation using a Dynamitron electron accelerator, the above mentioned testing methods and the results are reported. The nondestructive information on interface separation, microvoids and cracks in the matrix was given by acoustic microscope images. (K.I.)

  14. Defect Detection on Carbon Fibre Reinforced Plastics (cfrp) with Laser Generated Lamb Waves

    Science.gov (United States)

    Focke, O.; Huke, P.; Hildebrandt, A.

    2011-06-01

    Standard ultrasound methods using a phased-array or a single transducer are commonly used for non-destructive evaluation (NDE) during manufacturing of carbon fiber reinforced plastics (CFRP) parts and certificated testing schemes were developed for individual parts and geometries. However, most testing methods need direct contact, matching gels and remain therefore time consuming. Laser-Ultrasonics is advantageous due to the contactless measurement technology and high accessibility even on complex parts. Despite the non-destructive testing with body waves, we show that the NDE can be expanded using two-dimensional surface (Lamb) waves for detection of delaminations close to the surface or small deteriorations caused by e.g. impacts. Lamb waves have been excited with a single transducer and with a short-pulse Laser with additionally producing A0-and S0-Lamb waves. The waves were detected with a shearography setup that allows for measuring two-dimensionally the displacement of a surface. Short integration times of the camera were realized using a pulsed ruby laser for illumination. As a consequence to the anisotropy the propagation in different directions exhibits individual characteristics like amplitude, damping and velocity. This has motivated to build up models for the propagation of Lamb waves and to compare them with experimental results.

  15. Fretting Fatigue Behaviour of Pin-Loaded Thermoset Carbon-Fibre-Reinforced Polymer (CFRP Straps

    Directory of Open Access Journals (Sweden)

    Fabio Baschnagel

    2016-04-01

    Full Text Available This paper focuses on the fretting fatigue behaviour of pin-loaded carbon-fibre-reinforced polymer (CFRP straps studied as models for rigging systems in sailing yachts, for suspenders of arch bridges and for pendent cables in cranes. Eight straps were subjected to an ultimate tensile strength test. In total, 26 straps were subjected to a fretting fatigue test, of which ten did not fail. An S–N curve was generated for a load ratio R of 0.1 and a frequency f of 10 Hz, showing a fatigue limit stress of the straps around the matrix fatigue limit, corresponding to 46% of the straps’ ultimate tensile strength (σUTS. The fatigue limit was defined as 3 million load cycles (N = 3 × 106, but tests were even conducted up to N = 11.09 × 106. Catastrophic failure of the straps was initiated in their vertex areas. Investigations on the residual strength and stiffness properties of straps tested around the fatigue limit stress (for N ≥ 1 × 106 showed little influence of the fatigue loading on these properties. Quasi-static finite element analyses (FEA were conducted. The results obtained from the FEA are in good agreement with the experiments and demonstrate a fibre parallel stress concentration in the vertex area of factor 1.3, under the realistic assumption of a coefficient of friction (cof between pin and strap of 0.5.

  16. Interfacial stresses in damaged RC beams strengthened with externally bonded CFRP plate

    International Nuclear Information System (INIS)

    A theoretical method to predict the interfacial stresses in the adhesive layer of damaged reinforced concrete beams strengthened with externally bonded carbon fiber-reinforced polymer (CFRP) plate is presented. The adopted model is developed including the adherend shear deformations by assuming a linear shear stress through the depth of the RC beam [A. Tounsi, Int. J. Solids Struct., in press], while all existing solutions neglect this effect [e.g. S. Benyoucef, A. Tounsi, S.A. Meftah, E.A. Adda Bedia, Compos. Interfaces, in press; S.T. Smith, J.G. Teng, Eng. Struct. 23 (7) (2001) 857-871; T.M. Roberts, Struct. Eng. 67 (12) (1989) 229-233; A. Tounsi, S. Benyoucef, Int. J. Adhes. Adhes., in press; T. Stratford, J. Cadei, Construct. Building Mater. 20 (2006) 34-35]. In addition, in the present study the anisotropic damage model is adopted to describe the damage of the RC beams. It is shown that the damage has a significant effect on the interfacial stresses in FRP-damaged RC beam

  17. Behavior of Reinforced Concrete Box Beam Strengthened with CFRP U-Wrap Strips Under Torsion

    Directory of Open Access Journals (Sweden)

    Ma Shengqiang

    2016-01-01

    Full Text Available The present study focuses on the torsional strengthening behavior of reinforced concrete (RC box section beams that are widely used in bridges. Four RC box beams were fabricated, and three of them were wrapped by carbon fiber-reinforced polymer (CFRP U-wrap strips with or without longitudinal strips. The different wrapping configuration, cracking angle, failure pattern, and tensile strain of fibers were investigated and discussed accordingly. The experimental results addressed that U-wrap strips strengthening also can upgrade the ultimate torque of beams moderately. In particular, using U-wrap and longitudinal strips to bond the box beams increased the torsional stiffness slightly. The same equation from different codes for calculating RC specimens can accurately predict the ultimate strength of the control beam, but the calculation of the fib model overestimated the torsional strengthening improvement of the wrapped specimens. However, Ghobarah et al. assumed approximately 3000με of the average ultimate fiber strain in calculating the ultimate strength of the wrapped box beams which shows in relatively appropriate agreement with testing results.

  18. Shear strengthening of damaged reinforced concrete beams with hybrid composite plates

    OpenAIRE

    Baghi, Hadi; Barros, Joaquim A. O.; Rezazadeh, Mohammadali; Laranjeira, João Pedro Santos

    2015-01-01

    This paper aims to evaluate experimentally the potentialities of Hybrid Composite Plates (HCPs) technique for the shear strengthening of reinforced concrete (RC) beams that were previously subjected to intense damage in shear. HCP is a thin plate of Strain Hardening Cementitious Composite (SHCC) reinforced with Carbon Fiber Reinforced Polymer (CFRP) laminates. For this purpose, an experimental program composed of two series of beams (rectangular and T cross section) was executed t...

  19. Temperature and humidity dependent performance of FBG-strain sensors embedded in carbon/epoxy composites

    Science.gov (United States)

    Frövel, Malte; Carrión, Gabriel; Gutiérrez, César; Moravec, Carolina; Pintado, José María

    2009-03-01

    Fiber Bragg Grating Sensors, FBGSs, are very promising for Structural Health Monitoring, SHM, of aerospace vehicles due to their capacity to measure strain and temperature, their lightweight harnesses, their multiplexing capacities and their immunity to electromagnetic interferences, within others. They can be embedded in composite materials that are increasingly forming an important part of aerospace structures. The use of embedded FBGSs for SHM purposes is advantageous, but their response under all operative environmental conditions of an aerospace structure must be well understood for the necessary flight certification of these sensors. This paper describes the first steps ahead for a possible in future flight certification of FBGSs embedded in carbon fiber reinforced plastics, CFRP. The investigation work was focused on the validation of the dependence of the FBGS's strain sensitivity in tensile and compression load, in dry and humid condition and in a temperature range from -150°C to 120°C. The test conditions try to simulate the in service temperature and humidity range and static load condition of military aircraft. FBGSs with acrylic and with polyimide coating have been tested. The FBGSs are embedded in both, unidirectional and quasi isotropic carbon/epoxy composite material namely M21/T800 and also MTM-45-1/IM7. Conventional extensometers and strain gages have been used as reference strain sensors. The performed tests show an influence of the testing temperatures, the dry or wet specimen condition, the load direction and the coating material on the sensor strain sensitivity that should be taken into account when using these sensors.

  20. The velocity measurement of Se mode in the transient signals of lamb wave and determination of the Young's modulus in unidirectional and bidirectional CFRP plates

    International Nuclear Information System (INIS)

    Lamb waves were generated by breaking pencil leads on the surface and edge of unidirectional and (0 degree/90 degree) bidirectional carbon fibre reinforced plastic(CFRP) plates. The transient signals of Lamb waves were detected with two broad band piezoelectric transducers of 6.35 mm diameter with 10 MHz center frequency. The fundamental symmetric mode was identified by the power spectrum analysis and the group velocities of these modes were obtained by measuring the delay time of the signals received by two transducers placed at different positions. Young's moduli, determined with the group velocities of the fundamental symmetric mode, are 9.1 GPa and 120 GPa normal and along the fibre direction respectively in unidirectional CFRP plate. And those along the two fibre directions in [0 degree/90 degree]12s bidirectional CFRP plates are 64.8 GPa and 63.7 GPa, respectively.

  1. IDENTIFICATION OF AIRCRAFT HAZARDS

    International Nuclear Information System (INIS)

    Aircraft hazards were determined to be potentially applicable to a repository at Yucca Mountain in the ''Monitored Geological Repository External Events Hazards Screening Analysis'' (BSC 2004, Section 6.4.1). That determination was conservatively based on limited knowledge of flight data in the area of concern and on crash data for aircraft of the type flying near Yucca Mountain. The purpose of this report is to identify specific aircraft hazards that may be applicable to a Monitored Geologic Repository (MGR) at Yucca Mountain using NUREG-0800, ''Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants'' (NRC 1987, Section 3.5.1.6), as guidance for the inclusion or exclusion of identified aircraft hazards. NUREG-0800 is being used here as a reference because some of the same considerations apply. The intended use of this report is to provide inputs for further screening and analysis of the identified aircraft hazards based on the criteria that apply to Category 1 and 2 event sequence analyses as defined in 10 CFR 63.2 (see Section 4). The scope of this technical report includes the evaluation of military, private, and commercial use of airspace in the 100-mile regional setting of the MGR at Yucca Mountain with the potential for reducing the regional setting to a more manageable size after consideration of applicable screening criteria (see Section 7)

  2. Aircraft Operations Classification System

    Science.gov (United States)

    Harlow, Charles; Zhu, Weihong

    2001-01-01

    Accurate data is important in the aviation planning process. In this project we consider systems for measuring aircraft activity at airports. This would include determining the type of aircraft such as jet, helicopter, single engine, and multiengine propeller. Some of the issues involved in deploying technologies for monitoring aircraft operations are cost, reliability, and accuracy. In addition, the system must be field portable and acceptable at airports. A comparison of technologies was conducted and it was decided that an aircraft monitoring system should be based upon acoustic technology. A multimedia relational database was established for the study. The information contained in the database consists of airport information, runway information, acoustic records, photographic records, a description of the event (takeoff, landing), aircraft type, and environmental information. We extracted features from the time signal and the frequency content of the signal. A multi-layer feed-forward neural network was chosen as the classifier. Training and testing results were obtained. We were able to obtain classification results of over 90 percent for training and testing for takeoff events.

  3. Identification of Aircraft Hazards

    International Nuclear Information System (INIS)

    Aircraft hazards were determined to be potentially applicable to a repository at Yucca Mountain in ''Monitored Geological Repository External Events Hazards Screening Analysis'' (BSC 2005 [DIRS 174235], Section 6.4.1). That determination was conservatively based upon limited knowledge of flight data in the area of concern and upon crash data for aircraft of the type flying near Yucca Mountain. The purpose of this report is to identify specific aircraft hazards that may be applicable to a monitored geologic repository (MGR) at Yucca Mountain, using NUREG-0800, ''Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants'' (NRC 1987 [DIRS 103124], Section 3.5.1.6), as guidance for the inclusion or exclusion of identified aircraft hazards. The intended use of this report is to provide inputs for further screening and analysis of identified aircraft hazards based upon the criteria that apply to Category 1 and Category 2 event sequence analyses as defined in 10 CFR 63.2 [DIRS 176544] (Section 4). The scope of this report includes the evaluation of military, private, and commercial use of airspace in the 100-mile regional setting of the repository at Yucca Mountain with the potential for reducing the regional setting to a more manageable size after consideration of applicable screening criteria (Section 7)

  4. IDENTIFICATION OF AIRCRAFT HAZARDS

    Energy Technology Data Exchange (ETDEWEB)

    K.L. Ashley

    2005-03-23

    Aircraft hazards were determined to be potentially applicable to a repository at Yucca Mountain in the ''Monitored Geological Repository External Events Hazards Screening Analysis'' (BSC 2004, Section 6.4.1). That determination was conservatively based on limited knowledge of flight data in the area of concern and on crash data for aircraft of the type flying near Yucca Mountain. The purpose of this report is to identify specific aircraft hazards that may be applicable to a Monitored Geologic Repository (MGR) at Yucca Mountain using NUREG-0800, ''Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants'' (NRC 1987, Section 3.5.1.6), as guidance for the inclusion or exclusion of identified aircraft hazards. NUREG-0800 is being used here as a reference because some of the same considerations apply. The intended use of this report is to provide inputs for further screening and analysis of the identified aircraft hazards based on the criteria that apply to Category 1 and 2 event sequence analyses as defined in 10 CFR 63.2 (see Section 4). The scope of this technical report includes the evaluation of military, private, and commercial use of airspace in the 100-mile regional setting of the MGR at Yucca Mountain with the potential for reducing the regional setting to a more manageable size after consideration of applicable screening criteria (see Section 7).

  5. Identification of Aircraft Hazards

    Energy Technology Data Exchange (ETDEWEB)

    K. Ashley

    2006-12-08

    Aircraft hazards were determined to be potentially applicable to a repository at Yucca Mountain in ''Monitored Geological Repository External Events Hazards Screening Analysis'' (BSC 2005 [DIRS 174235], Section 6.4.1). That determination was conservatively based upon limited knowledge of flight data in the area of concern and upon crash data for aircraft of the type flying near Yucca Mountain. The purpose of this report is to identify specific aircraft hazards that may be applicable to a monitored geologic repository (MGR) at Yucca Mountain, using NUREG-0800, ''Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants'' (NRC 1987 [DIRS 103124], Section 3.5.1.6), as guidance for the inclusion or exclusion of identified aircraft hazards. The intended use of this report is to provide inputs for further screening and analysis of identified aircraft hazards based upon the criteria that apply to Category 1 and Category 2 event sequence analyses as defined in 10 CFR 63.2 [DIRS 176544] (Section 4). The scope of this report includes the evaluation of military, private, and commercial use of airspace in the 100-mile regional setting of the repository at Yucca Mountain with the potential for reducing the regional setting to a more manageable size after consideration of applicable screening criteria (Section 7).

  6. Lamb wave detection in prepreg composite materials with fibre Bragg grating sensors

    Science.gov (United States)

    Miesen, Nick; Mizutani, Yoshihiro; Groves, Roger M.; Sinke, Jos; Benedictus, Rinze

    2011-04-01

    This paper demonstrates that existing Structural Health Monitoring (SHM) techniques have potential during the production phase in addition to their application for maintenance and for in-flight monitoring. Flaws occur during composite fabrication in industry, due to an imperfect process control and human errors. This decreases production efficiency and increases costs. In this paper, the monitoring of Lamb waves in unidirectional carbon fibre (UD-CFRP) prepreg material is demonstrated using both Fibre Bragg Gratings (FBG)s and piezolectric acoustic sensors, and that these SHM sensors may be used for flaw detection and production monitoring. The detection of Lamb waves in a one ply thick sheet of prepreg UD-CFRP material is demonstrated for an FBG sensor aligned with the carbon fibre orientation and bonded to the surface of the prepreg, Furthermore, the velocity of Lamb waves in prepreg UD-CFRP in different orientations is investigated. Finally the successful detection of a material crack in a prepreg UD-CFRP sheet using the Lamb wave detection method is demonstrated.

  7. Nondestructive Evaluation of Carbon Fiber Reinforced Polymer Composites Using Reflective Terahertz Imaging.

    Science.gov (United States)

    Zhang, Jin; Li, Wei; Cui, Hong-Liang; Shi, Changcheng; Han, Xiaohui; Ma, Yuting; Chen, Jiandong; Chang, Tianying; Wei, Dongshan; Zhang, Yumin; Zhou, Yufeng

    2016-01-01

    Terahertz (THz) time-domain spectroscopy (TDS) imaging is considered a nondestructive evaluation method for composite materials used for examining various defects of carbon fiber reinforced polymer (CFRP) composites and fire-retardant coatings in the reflective imaging modality. We demonstrate that hidden defects simulated by Teflon artificial inserts are imaged clearly in the perpendicular polarization mode. The THz TDS technique is also used to measure the thickness of thin fire-retardant coatings on CFRP composites with a typical accuracy of about 10 micrometers. In addition, coating debonding is successfully imaged based on the time-delay difference of the time-domain waveforms between closely adhered and debonded sample locations. PMID:27314352

  8. Nondestructive Evaluation of Carbon Fiber Reinforced Polymer Composites Using Reflective Terahertz Imaging

    Directory of Open Access Journals (Sweden)

    Jin Zhang

    2016-06-01

    Full Text Available Terahertz (THz time-domain spectroscopy (TDS imaging is considered a nondestructive evaluation method for composite materials used for examining various defects of carbon fiber reinforced polymer (CFRP composites and fire-retardant coatings in the reflective imaging modality. We demonstrate that hidden defects simulated by Teflon artificial inserts are imaged clearly in the perpendicular polarization mode. The THz TDS technique is also used to measure the thickness of thin fire-retardant coatings on CFRP composites with a typical accuracy of about 10 micrometers. In addition, coating debonding is successfully imaged based on the time-delay difference of the time-domain waveforms between closely adhered and debonded sample locations.

  9. Guided Wave Propagation Study on Laminated Composites by Frequency-Wavenumber Technique

    Science.gov (United States)

    Tian, Zhenhua; Yu, Lingyu; Leckey, Cara A. C.

    2014-01-01

    Toward the goal of delamination detection and quantification in laminated composites, this paper examines guided wave propagation and wave interaction with delamination damage in laminated carbon fiber reinforced polymer (CFRP) composites using frequency-wavenumber (f-kappa) analysis. Three-dimensional elastodynamic finite integration technique (EFIT) is used to acquire simulated time-space wavefields for a CFRP composite. The time-space wavefields show trapped waves in the delamination region. To unveil the wave propagation physics, the time-space wavefields are further analyzed by using two-dimensional (2D) Fourier transforms (FT). In the analysis results, new f-k components are observed when the incident guided waves interact with the delamination damage. These new f-kappa components in the simulations are experimentally verified through data obtained from scanning laser Doppler vibrometer (SLDV) tests. By filtering the new f-kappa components, delamination damage is detected and quantified.

  10. Investigation of composite materials using SLM-based phase retrieval.

    Science.gov (United States)

    Agour, Mostafa; Falldorf, Claas; Bergmann, Ralf B

    2013-07-01

    We present a robust method to inspect a typical composite material constructed of carbon fiber reinforced plastic (CFRP). It is based on optical surface contouring using the spatial light modulator (SLM)-based phase retrieval technique. The method utilizes multiple intensity observations of the wave field, diffracted by the investigated object, captured at different planes along the optical axis to recover the phase information across the object plane. The SLM-based system allows for the recording of the required consecutive intensity measurements in various propagation states across a common recording plane. This overcomes the mechanical shifting of a camera sensor required within the capturing process. In contrast to existing phase retrieval approaches, the measuring time is considerably reduced, since the switching time of the SLM is less than 50 ms. This enables nondestructive testing under thermal load. Experimental results are presented that demonstrate the approach can be used to assess structural properties of technical components made from CFRP.

  11. Investigation of composite materials using SLM-based phase retrieval.

    Science.gov (United States)

    Agour, Mostafa; Falldorf, Claas; Bergmann, Ralf B

    2013-07-01

    We present a robust method to inspect a typical composite material constructed of carbon fiber reinforced plastic (CFRP). It is based on optical surface contouring using the spatial light modulator (SLM)-based phase retrieval technique. The method utilizes multiple intensity observations of the wave field, diffracted by the investigated object, captured at different planes along the optical axis to recover the phase information across the object plane. The SLM-based system allows for the recording of the required consecutive intensity measurements in various propagation states across a common recording plane. This overcomes the mechanical shifting of a camera sensor required within the capturing process. In contrast to existing phase retrieval approaches, the measuring time is considerably reduced, since the switching time of the SLM is less than 50 ms. This enables nondestructive testing under thermal load. Experimental results are presented that demonstrate the approach can be used to assess structural properties of technical components made from CFRP. PMID:23811877

  12. Loading and fracture response of CFRP-to-steel adhesively bonded joints with thick adherents – Part I: Experiments

    DEFF Research Database (Denmark)

    Anyfantis, Konstantinos; Tsouvalis, Nicholas G.

    2013-01-01

    and fracture response of such joints, but limited to joints with thin adherents. On this basis, the present work provides an experimental parametric study of adhesively bonded Single Lap Joint geometries between thick dissimilar adherents. For this purpose, mild steel and CFRP laminates have been considered...... in the adhesive bondline. The global response was recorded and corresponding results are presented. It was concluded that for the current material systems and geometries tested, the effect of the adhesive thickness and stiffness ratio is negligible compared to the effect of the overlap length to the stiffness...

  13. Auralization of novel aircraft configurations

    OpenAIRE

    Arntzen, M.; Bertsch, E.L.; Simons, D.G.

    2015-01-01

    A joint initiative of NLR, DLR, and TU Delft has been initiated to streamline the process of generating audible impressions of novel aircraft configurations. The integrated approach adds to the value of the individual tools and allows predicting the sound of future aircraft before they actually fly. Hence, an existing process for the aircraft design and system noise prediction at DLR has been upgraded to generate the required input data for an aircraft auralization framework developed by NLR ...

  14. Long Range Aircraft Trajectory Prediction

    OpenAIRE

    Magister, Tone

    2009-01-01

    The subject of the paper is the improvement of the aircraft future trajectory prediction accuracy for long-range airborne separation assurance. The strategic planning of safe aircraft flights and effective conflict avoidance tactics demand timely and accurate conflict detection based upon future four–dimensional airborne traffic situation prediction which is as accurate as each aircraft flight trajectory prediction. The improved kinematics model of aircraft relative flight considering flight ...

  15. Debris of carbon-fibers originated from a CFRP (pEEK) wrist-plate triggered a destruent synovitis in human.

    Science.gov (United States)

    Merolli, Antonio; Rocchi, Lorenzo; De Spirito, Marco; Federico, Francesco; Morini, Alessandro; Mingarelli, Luigi; Fanfani, Francesco

    2016-03-01

    Application of carbon-fiber-reinforced-polymer (CFRP) artifacts in humans has been promoted in Orthopedic and Trauma Surgery. Literature documents the biocompatibility of materials used, namely carbon fibers (CF) and poly-ether thermoplastics, like poly-ether-ether-ketone (PEEK). A properly designed and accurately implanted composite artifact should not expose its fibers during or after surgery: however this may happen. A white Caucasian woman came to our attention 11 months after surgery for a wrist fracture. She had a severe impairment, being unable to flex the thumb; index finger and distal phalanx of third finger. We retrieved a correctly positioned plate and documented an aggressive erosive flexor tendons synovitis with eroded stumps of flexor tendons. The plate and soft tissues were analyzed by Visible Light and Scanning Electron Microscopy. Histopathology showed granulomatous fibrogenic process with CF engulfed inside multinucleated giant cells. Fibers were unmasked and disrupted inside the holes where screws were tightened and corrugation of the polymer coating led to further unmasking. The mechanism of foreign-body reaction to CF has not been studied in depth yet, particularly at the ultrastructural level and in Humans. This case documents a damage occurred in a clinical application and which was theoretically possible. Our opinion is that a proper way to promote the use of CRFP in the Clinic in the short term is to direct Research towards finding a better way to prevent CF debris to be exposed and released. In the longer term, the biological response to CF deserves a deeper understanding.

  16. Aircraft noise prediction

    Science.gov (United States)

    Filippone, Antonio

    2014-07-01

    This contribution addresses the state-of-the-art in the field of aircraft noise prediction, simulation and minimisation. The point of view taken in this context is that of comprehensive models that couple the various aircraft systems with the acoustic sources, the propagation and the flight trajectories. After an exhaustive review of the present predictive technologies in the relevant fields (airframe, propulsion, propagation, aircraft operations, trajectory optimisation), the paper addresses items for further research and development. Examples are shown for several airplanes, including the Airbus A319-100 (CFM engines), the Bombardier Dash8-Q400 (PW150 engines, Dowty R408 propellers) and the Boeing B737-800 (CFM engines). Predictions are done with the flight mechanics code FLIGHT. The transfer function between flight mechanics and the noise prediction is discussed in some details, along with the numerical procedures for validation and verification. Some code-to-code comparisons are shown. It is contended that the field of aircraft noise prediction has not yet reached a sufficient level of maturity. In particular, some parametric effects cannot be investigated, issues of accuracy are not currently addressed, and validation standards are still lacking.

  17. Robots for Aircraft Maintenance

    Science.gov (United States)

    1993-01-01

    Marshall Space Flight Center charged USBI (now Pratt & Whitney) with the task of developing an advanced stripping system based on hydroblasting to strip paint and thermal protection material from Space Shuttle solid rocket boosters. A robot, mounted on a transportable platform, controls the waterjet angle, water pressure and flow rate. This technology, now known as ARMS, has found commercial applications in the removal of coatings from jet engine components. The system is significantly faster than manual procedures and uses only minimal labor. Because the amount of "substrate" lost is minimal, the life of the component is extended. The need for toxic chemicals is reduced, as is waste disposal and human protection equipment. Users of the ARMS work cell include Delta Air Lines and the Air Force, which later contracted with USBI for development of a Large Aircraft Paint Stripping system (LARPS). LARPS' advantages are similar to ARMS, and it has enormous potential in military and civil aircraft maintenance. The technology may also be adapted to aircraft painting, aircraft inspection techniques and paint stripping of large objects like ships and railcars.

  18. 侵蚀性环境下桥梁CFRP/BFRP加固后的长期性能试验%Experiment for Long-term Performance of Bridge Girders Strengthened with CFRP/BFRP Sheets and Subjected to Erosion Environment

    Institute of Scientific and Technical Information of China (English)

    孙晓燕; 董伟伟; 王海龙; 何世钦

    2013-01-01

    为了研究侵蚀性环境下服役桥梁构件采用纤维材料加固后的长期性能,对11根具有初始锈蚀损伤的钢筋混凝土梁式构件采用碳纤维布(CFRP)和玄武岩纤维布(BFRP)加固后继续退化的承载力及服役性能进行试验.通过对加固后构件进行电化学加速锈蚀和盐液浸润干湿循环模拟不同程度的后续服役性能退化,研究侵蚀性环境对CFRP和BFRP加固构件在不同后续服役期的承载力、刚度等性能影响规律,同时对比了2种加固材料的耐久性能和成本效益.结果表明:侵蚀性环境下加固后的桥梁构件承载能力评估需综合考虑钢筋锈蚀引起的承载力降低和侵蚀性环境对纤维利用效率的降低;CFRP对刚度提高显著,而BFRP加固具有更好的延性;考虑加固后长期服役性能,CFRP加固后具有较好的耐久性,而BFRP具有较高的成本效益.%To investigate the long-term performance of existing bridge girders strengthened with fiber reinforced plastics (FRP) sheets and subjected to erosion environment, the bearing capacity and service performance experiments of 11 reinforced concrete (RC) girders, which were strengthened with carbon fiber reinforced plastics (CFRP) and basalt fiber reinforced polymer (BFRP) sheets after initial corrosion damage, were conducted. Different subsequent performance degradations for strengthened girders were simulated through electrochemical accelerated corrosion together with wet/dry cycles of salt solution. The effect of environmental erosion on capacity, stiffness and other parameters of CFRP/BFRP strengthened girders in different follow-up service time was tested. The durabilities and costs of the two strengthening materials were also investigated. The results show that the capacity evaluation of bridge girders strengthened with FRP sheets should consider the effect of rebar corrosion together with the environmental reduction of FRP strengthening; the CFRP strengthening improves

  19. Braking performance of aircraft tires

    Science.gov (United States)

    Agrawal, Satish K.

    This paper brings under one cover the subject of aircraft braking performance and a variety of related phenomena that lead to aircraft hydroplaning, overruns, and loss of directional control. Complex processes involving tire deformation, tire slipping, and fluid pressures in the tire-runway contact area develop the friction forces for retarding the aircraft; this paper describes the physics of these processes. The paper reviews the past and present research efforts and concludes that the most effective way to combat the hazards associated with aircraft landings and takeoffs on contaminated runways is by measuring and displaying in realtime the braking performance parameters in the aircraft cockpit.

  20. Assessment of the efficiency of prefabricated hybrid composite plates (HCPs) for retrofitting of damaged interior RC beam–column joints

    OpenAIRE

    Esmaeeli, Esmaeel; Barros, Joaquim A. O.; Sena-Cruz, José; Varum, H.; Melo, J.

    2015-01-01

    The effectiveness of prefabricated hybrid composite plates (HCPs) as a seismic retrofitting solution for damaged interior RC beam-column joints is experimentally studied. HCP is composed of a thin plate made of strain hardening cementitious composite (SHCC) reinforced with CFRP sheets/laminates. Two full-scale severely damaged interior beam-column joints are retrofitted using two different configurations of HCPs. The effectiveness of these retrofitting solutions mainly in terms of hysteretic ...

  1. Compression Molding of Chemical/Thermal Resistant Composite Materials Using Wastes of Glass Fiber Reinforced PTFE and Carbon Fiber

    OpenAIRE

    Kimura, Teruo||木村, 照夫||キムラ, テルオ

    2013-01-01

    This report proposed the compression molding method of chemical/thermal resistant composite materials reinforced by the carbon fiber extracted from CFRP waste and the waste of glass fiber coated by PTFE. The FEP resin was used for the matrix material. The contents of carbon fiber and FEP resin were varied in the experiments, and the machanical properties of composite materials were discussed in detail. As a result, the bending strength and modulus increased with increasing the content of carb...

  2. Assessing and controlling the effect of aircraft on the environment: Pollution

    Science.gov (United States)

    Poppoff, I. G.; Grobman, J. S.

    1975-01-01

    The air pollution created by aircraft engines around airports and the global atmospheric problem of supersonic aircraft operating in the stratosphere are discussed. Methods for assessing the air pollution impact are proposed. The use of atmospheric models to determine the air pollution extent is described. Methods for controlling the emissions of aircraft engines are examined. Diagrams of the atmospheric composition resulting from exhaust gas emissions are developed.

  3. REVERSE ENGINEERING IN MODELING OF AIRCRAFT PROPELLER BLADE - FIRST STEP TO PRODUCT OPTIMIZATION

    OpenAIRE

    Muhammad Yasir Anwar; Shahid Ikramullah; Farrukh Mazhar

    2014-01-01

    ABSTRACT: Propeller aircrafts have had many ups and downs throughout their use in the aviation history. Due to the current economic recession and price hikes in fuels, propeller aircrafts may yet again be a choice for aerial transport and has thus re-emerged as an active area for research. On modern propeller aircrafts old aluminum propellers are being replaced with fiber reinforced composite propellers. However, owing to their reliability, strength, and integrity, aluminum propellers are sti...

  4. Pollution from Aircraft Emissions in the North Atlantic Flight Corridor: Overview on the POLINAT Projects

    OpenAIRE

    Schumann, U.; H. Schlager; F. Arnold; J. Ovarlez; Kelder, H.; O. Hov; Hayman, G.; I. S. A. Isaksen; Staehelin, J.; Whitefield, P.D.

    2000-01-01

    The Pollution From Aircraft Emissions in the North Atlantic Flight Corridor (POLINAT) projects were undertaken to investigate the impact of aircraft engine exhaust emissions on the state of the atmosphere in the North Atlantic flight corridor. Changes in the composition of the lower stratosphere and upper troposphere from aircraft emissions are identified from combined measurements and model analyses. Measurements were performed using the Deutsches Zentrum für Luft- und Raumfahrt Falcon resea...

  5. Fatigue and post-fatigue performance of Fabry-Perot FOS installed on CFRP-strengthened RC-beams

    Science.gov (United States)

    Gheorghiu, Catalin; Labossiere, Pierre; Proulx, Jean

    2004-07-01

    There is a growing need for built-in monitoring systems for civil engineering infrastructures, due to problems such as increasing traffic loads and rising costs of maintenance and repair. Fibre optic sensors (FOS), capable of reading various parameters are promising candidates for life-long health monitoring of these structures. However, since FOS have only been introduced recently into the field of structural monitoring, their acceptance and widespread implementation will be conditioned by their durability under severe climatic and loading conditions. This paper reports on the performance of strain extrinsic FOS attached to carbon fibre reinforced polymer (CFRP) plates used to strengthen concrete structures. The specimens tested in this project are reinforced concrete (RC) beams with an additional external CFRP reinforcement. The FOS-instrumented beams were first subjected to fatigue loading for various numbers of cycles and load amplitudes. Then, they were tested monotonically to failure under four-point-bending. The test results provide an insight on the fatigue and post-fatigue behaviour of FOS used for monitoring reinforced concrete structures.

  6. Recent progress in composite materials application for Ariane

    Science.gov (United States)

    Klug, J.; Kalk, K. W.

    Reductions in dry mass by using carbon fiber reinforced plastics (CFRP) in launch vehicles are illustrated. The interstage structure of the Ariane second stage as CFRP and metal structure are compared. The CFRP shell comprises built up walls of inner and outer skin, covering stiffening stringers and frames. Attachment flanges are also made of CFRP. The CFRP structure mass is 157 kg, compared with 240 kg for aluminum.

  7. The effects of aircraft on climate and pollution. Part II: 20-year impacts of exhaust from all commercial aircraft worldwide treated individually at the subgrid scale.

    Science.gov (United States)

    Jacobson, M Z; Wilkerson, J T; Naiman, A D; Lele, S K

    2013-01-01

    This study examines the 20-year impacts of emissions from all commercial aircraft flights worldwide on climate, cloudiness, and atmospheric composition. Aircraft emissions from each individual flight worldwide were modeled to evolve from the subgrid to grid scale with the global model described and evaluated in Part I of this study. Simulations with and without aircraft emissions were run for 20 years. Aircraft emissions were found to be responsible for -6% of Arctic surface global warming to date, -1.3% of total surface global warming, and -4% of global upper tropospheric warming. Arctic warming due to aircraft slightly decreased Arctic sea ice area. Longer simulations should result in more warming due to the further increase in CO2. Aircraft increased atmospheric stability below cruise altitude and decreased it above cruise altitude. The increase in stability decreased cumulus convection in favor of increased stratiform cloudiness. Aircraft increased total cloud fraction on average. Aircraft increased surface and upper tropospheric ozone by -0.4% and -2.5%, respectively and surface and upper-tropospheric peroxyacetyl nitrate (PAN) by -0.1% and -5%, respectively. Aircraft emissions increased tropospheric OH, decreasing column CO and CH4 by -1.7% and -0.9%, respectively. Aircraft emissions increased human mortality worldwide by -620 (-240 to 4770) deaths per year, with half due to ozone and the rest to particulate matter less than 2.5 micrometers in diameter (PM2.5). PMID:24601012

  8. Standardization of Tests for Advanced Composites

    OpenAIRE

    石川, 隆司; Ishikawa, Takashi; 野口, 義男; Noguchi, Yoshio; 濱口, 泰正; Hamaguchi, Yasumasa

    2003-01-01

    Advanced composites are essentially the only feasible materials for the construction of newly developed aerospace vehicle. However, the path to be followed for the validation, evaluation and certification of composite aircraft structures is quite different from that of traditional metallic aircraft structures, and the importance of a composites database is now well recognized. A key issue in constructing a fully descriptive composites database is to establish standard composite test methods, ...

  9. 19 CFR 10.183 - Duty-free entry of civil aircraft, aircraft engines, ground flight simulators, parts, components...

    Science.gov (United States)

    2010-04-01

    ... Duty-free entry of civil aircraft, aircraft engines, ground flight simulators, parts, components, and... aircraft, aircraft engines, and ground flight simulators, including their parts, components, and... United States (HTSUS) by meeting the following requirements: (1) The aircraft, aircraft engines,...

  10. Research of carbon composite material for nonlinear finite element method

    Science.gov (United States)

    Kim, Jung Ho; Garg, Mohit; Kim, Ji Hoon

    2012-04-01

    Works on the absorption of collision energy in the structural members are carried out widely with various material and cross-sections. And, with ever increasing safety concerns, they are presently applied in various fields including railroad trains, air crafts and automobiles. In addition to this, problem of lighting structural members became important subject by control of exhaust gas emission, fuel economy and energy efficiency. CFRP(Carbon Fiber Reinforced Plastics) usually is applying the two primary structural members because of different result each design parameter as like stacking thickness, stacking angle, moisture absorption ect. We have to secure the data for applying primary structural members. But it always happens to test design parameters each for securing the data. So, it has much more money and time. We can reduce the money and the time, if can ensure the CFRP material properties each design parameters. In this study, we experiment the coupon test each tension, compression and shear using CFRP prepreg sheet and simulate non-linear analyze at the sources - test result, Caron longitudinal modulus and matrix poisson's ratio using GENOAMQC is specialized at Composite analysis. And then we predict the result that specimen manufacture changing stacking angle and experiment in such a way of test method using GENOA-MCQ.

  11. Applicability Study of Composite Laminates to the Cryogenic Propellant Tanks

    Science.gov (United States)

    Aoki, T.; Ishikawa, T.

    2002-01-01

    Extensive application of light weight composite materials is one of the major technical challenges for drastic reduction of structural weight of the planned reusable launch vehicles (RLV) and space planes. Cryogenic propellant tanks are the dominating structural components of the vehicle structure and thus the application of carbon fiber reinforced plastics (CFRP) to these components is one of the most promising but challenging technologies for achieving the aimed goal of weight reduction. Research effort has been made to scrutinize the cryogenic mechanical performance of currently available candidates of CFRP material systems suitable for use under cryogenic conditions. Seven different types of material systems of CFRP are chosen and are experimentally and analytically evaluated to discuss their applicability to the liquid propellant tanks and to provide basic information for material selections. Static tensile tests were conducted with quasi-isotropic laminates to acquire static strengths, both under cryogenic and room temperatures. The development of matrix cracks and free-edge delaminations were also experimentally investigated and were compared with the numerical calculations. Interlaminar fracture toughness at cryogenic temperature was also evaluated to investigate the damage susceptibility of the materials. The decrease in matrix crack onset stresses observed in the laminate performance experiments suggested that the propellant leakage may be a key issue when applying CFRP to the propellant tanks, as well as the durability concern. Thus the propellant leakage under matrix crack accumulation was simulated by the gas helium leakage tests. Leakage model was also developed and successfully applied to the prediction of the propellant leakage. Preliminary results of adhesive joint tests under cryogenic conditions will also be referred to.

  12. Lamb wave detection in prepreg composite materials with fibre Bragg grating sensors

    OpenAIRE

    Miesen. N.; Mizutani, Y; Groves, R.M.; Sinke, J.; Benedictus, R.

    2011-01-01

    This paper demonstrates that existing Structural Health Monitoring (SHM) techniques have potential during the production phase in addition to their application for maintenance and for in-flight monitoring. Flaws occur during composite fabrication in industry, due to an imperfect process control and human errors. This decreases production efficiency and increases costs. In this paper, the monitoring of Lamb waves in unidirectional carbon fibre (UD-CFRP) prepreg material is demonstrated using b...

  13. Delamination effects on cracked steel members reinforced by prestressed composite patch

    OpenAIRE

    Colombi, P.; Bassetti, A.; Nussbaumer, A

    2002-01-01

    Prestressed composite patch bonded on cracked steel section is a promising technique to reinforce cracked details or to prevent fatigue cracking on steel structural elements. It introduces compressive stresses that produce crack closure effect. Moreover, it modifies the crack geometry by bridging the crack lips and reduces the stress range at crack tip. Fatigue tests were performed on notched steel plate reinforced by CFRP strips as a step toward the validation of crack patching for fatigue l...

  14. Improving the vacuum-infusion process to manufacture high quality structural composite for the aeronautic market

    OpenAIRE

    Oliveira, Luís; Nunes, J. P.; F. Ferreira

    2014-01-01

    In last years, the vacuum-infusion processing method is being replacing successfully autoclave technologies to manufacture advanced composite structures, namely, the carbon-fibre reinforced plastic (CFRP) ones, for aeronautical and aerospace applications. The high investment associated with autoclave “prepreg” manufacturing has prompted interest in the use of alternative vacuum-infusion technologies that proven to be much more cost-effective processing methods. The present work presents, desc...

  15. A Fiber Optic Doppler Sensor and Its Application in Debonding Detection for Composite Structures

    OpenAIRE

    Fucai Li; Hideaki Murayama; Kazuro Kageyama; Guang Meng; Isamu Ohsawa; Takehiro Shirai

    2010-01-01

    Debonding is one of the most important damage forms in fiber-reinforced composite structures. This work was devoted to the debonding damage detection of lap splice joints in carbon fiber reinforced plastic (CFRP) structures, which is based on guided ultrasonic wave signals captured by using fiber optic Doppler (FOD) sensor with spiral shape. Interferometers based on two types of laser sources, namely the He-Ne laser and the infrared semiconductor laser, are proposed and compared in this study...

  16. Mission management aircraft operations manual

    Science.gov (United States)

    1992-01-01

    This manual prescribes the NASA mission management aircraft program and provides policies and criteria for the safe and economical operation, maintenance, and inspection of NASA mission management aircraft. The operation of NASA mission management aircraft is based on the concept that safety has the highest priority. Operations involving unwarranted risks will not be tolerated. NASA mission management aircraft will be designated by the Associate Administrator for Management Systems and Facilities. NASA mission management aircraft are public aircraft as defined by the Federal Aviation Act of 1958. Maintenance standards, as a minimum, will meet those required for retention of Federal Aviation Administration (FAA) airworthiness certification. Federal Aviation Regulation Part 91, Subparts A and B, will apply except when requirements of this manual are more restrictive.

  17. 19 CFR 122.64 - Other aircraft.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Other aircraft. 122.64 Section 122.64 Customs... AIR COMMERCE REGULATIONS Clearance of Aircraft and Permission To Depart § 122.64 Other aircraft. Clearance or permission to depart shall be requested by the aircraft commander or agent for aircraft...

  18. Guidance Systems of Fighter Aircraft

    Directory of Open Access Journals (Sweden)

    K.N. Rajanikanth

    2005-07-01

    Full Text Available Mission performance of a fighter aircraft is crucial for survival and strike capabilities in todays' aerial warfare scenario. The guidance functions of such an aircraft play a vital role inmeeting the requirements and accomplishing the mission success. This paper presents the requirements of precision guidance for various missions of a fighter aircraft. The concept ofguidance system as a pilot-in-loop system is pivotal in understanding and designing such a system. Methodologies of designing such a system are described.

  19. Advanced composites: Design and application. Proceedings of the meeting of the Mechanical Failures Prevention Group

    Science.gov (United States)

    Shives, T. R.; Willard, W. A.

    1979-01-01

    The design and application of advanced composites is discussed with emphasis on aerospace, aircraft, automotive, marine, and industrial applications. Failure modes in advanced composites are also discussed.

  20. Study on the Shear Strength Calculation of Masonry Walls Strengthened with CFRP%粘贴CFRP砖砌体墙受剪承载力计算方法

    Institute of Scientific and Technical Information of China (English)

    左宏亮; 郭亮; 樊越

    2013-01-01

    The purpose of this paper is to propose the calculation formula of coefficients of exertion for CFRP strain and the applicable conditions in brick masonry walls strengthened with CFRP under low cyclic loading. Combining with the authors'experience and related references, experimental data of 4 groups of brick masonry walls strengthened with CFRP with different height-width ratio under low cyclic loading are analyzed,coefficients of exertion for CFRP strain and the measured value of shear capacity provided by CFRP are obtained. Then the relationship between coefficients of exertion for CFRP strain and height-width ratio is studied, the calculation formula of coefficients of exertion for CFRP strain is proposed and the consistency between the measured value and the theoretical value is checked. The results show that there is an approximate linear relationship between coefficients of exertion for CFRP strain and height-width ratio when the height-width ratio of a brick masonry walls is between 0. 56 and 0. 71 and the calculation formula is α = 0. 923 -0. 85 8 A ,The average ratios of the measured value of shear capacity provided by CFRP to the theo-retical value is 1. 07, standard deviation is 0. 33 and variation coefficient is 0. 31. The conclusions show that when the height-width ratio of brick masonry walls is between 0. 56 and 0. 71, the calculation formula of coefficients of exertion for CFRP strain can accurately figure out the value of the shear capacity provided by CFRP and has certain guidance in the field of seismic strengthening design of masonry walls in actual engineering. When σy/fm <0. 32 and the stickup method of CFRP could not effectively inhibit the emergence of horizontal cracks,or 0. 67≤σy/fm < 1. 0,the increasing shear capacity provided by CFRP should be ignored. As for the brick masonry wall which is strengthened with a large amount of CFRP,the pattern of diagonal compression failure should be discriminated..%目的 研究粘贴CFRP砖砌