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Sample records for strain distribution measurement

  1. Micro/Nano-scale Strain Distribution Measurement from Sampling Moiré Fringes.

    Science.gov (United States)

    Wang, Qinghua; Ri, Shien; Tsuda, Hiroshi

    2017-05-23

    This work describes the measurement procedure and principles of a sampling moiré technique for full-field micro/nano-scale deformation measurements. The developed technique can be performed in two ways: using the reconstructed multiplication moiré method or the spatial phase-shifting sampling moiré method. When the specimen grid pitch is around 2 pixels, 2-pixel sampling moiré fringes are generated to reconstruct a multiplication moiré pattern for a deformation measurement. Both the displacement and strain sensitivities are twice as high as in the traditional scanning moiré method in the same wide field of view. When the specimen grid pitch is around or greater than 3 pixels, multi-pixel sampling moiré fringes are generated, and a spatial phase-shifting technique is combined for a full-field deformation measurement. The strain measurement accuracy is significantly improved, and automatic batch measurement is easily achievable. Both methods can measure the two-dimensional (2D) strain distributions from a single-shot grid image without rotating the specimen or scanning lines, as in traditional moiré techniques. As examples, the 2D displacement and strain distributions, including the shear strains of two carbon fiber-reinforced plastic specimens, were measured in three-point bending tests. The proposed technique is expected to play an important role in the non-destructive quantitative evaluations of mechanical properties, crack occurrences, and residual stresses of a variety of materials.

  2. Distributed strain measurement in perfluorinated polymer optical fibres using optical frequency domain reflectometry

    International Nuclear Information System (INIS)

    Liehr, Sascha; Wendt, Mario; Krebber, Katerina

    2010-01-01

    We present the latest advances in distributed strain measurement in perfluorinated polymer optical fibres (POFs) using backscatter techniques. Compared to previously introduced poly(methyl methacrylate) POFs, the measurement length can be extended to more than 500 m at improved spatial resolution of a few centimetres. It is shown that strain in a perfluorinated POF can be measured up to 100%. In parallel to these investigations, the incoherent optical frequency domain reflectometry (OFDR) technique is introduced to detect strained fibre sections and to measure distributed length change along the fibre with sub-millimetre resolution by applying a cross-correlation algorithm to the backscatter signal. The overall superior performance of the OFDR technique compared to the optical time domain reflectometry in terms of accuracy, dynamic range, spatial resolution and measurement speed is presented. The proposed sensor system is a promising technique for use in structural health monitoring applications where the precise detection of high strain is required

  3. Simultaneous measurement of dynamic strain and temperature distribution using high birefringence PANDA fiber Bragg grating

    Science.gov (United States)

    Zhu, Mengshi; Murayama, Hideaki

    2017-04-01

    New approach in simultaneous measurement of dynamic strain and temperature has been done by using a high birefringence PANDA fiber Bragg grating sensor. By this technique, we have succeeded in discriminating dynamic strain and temperature distribution at the sampling rate of 800 Hz and the spatial resolution of 1 mm. The dynamic distribution of strain and temperature were measured with the deviation of 5mm spatially. In addition, we have designed an experimental setup by which we can apply quantitative dynamic strain and temperature distribution to the fiber under testing without bounding it to a specimen.

  4. Distributed strain measurement using modal interference in a birefringent optical fiber

    International Nuclear Information System (INIS)

    Kumar, Dilip; Sengupta, S; Ghorai, S K

    2008-01-01

    We propose a method based on modal interference in a birefringent optical fiber for distributed strain measurement. A frequency-modulated optical signal from a laser diode was launched in a birefringent fiber whose 'V' number was set in the range 2.405–3.831. The beat signal produced due to the interference of two lower order modes LP 01 and LP 11 was detected in a photodetector. The change in propagation constants between two modes under loading conditions leads to a phase variation of interference signal. The amplitude of the beat frequency was measured in the frequency domain by varying the modulating frequency, and it provides the measurand distribution along the beam. Results for strain distribution of a simply supported beam (51.0 cm × 3.0 cm × 0.6 cm) for an applied load of 250–1500 g are presented

  5. Distributed strain measurement with polymer optical fibers integrated into multifunctional geotextiles

    Science.gov (United States)

    Liehr, Sascha; Lenke, Philipp; Krebber, Katerina; Seeger, Monika; Thiele, Elke; Metschies, Heike; Gebreselassie, Berhane; Münich, Johannes Christian; Stempniewski, Lothar

    2008-04-01

    Fiber optic sensors based on polymer optical fibers (POF) have the advantage of being very elastic and robust at the same time. Unlike silica fibers, standard PMMA POF fibers can be strained to more than 40% while fully maintaining their light guiding properties. We investigated POF as a distributed strain sensor by analysing the backscatter increase at the strained section using the optical time domain reflectometry (OTDR) technique. This sensing ability together with its high robustness and break-down strain makes POF well-suited for integration into technical textiles for structural health monitoring purposes. Within the European research project POLYTECT (Polyfunctional textiles against natural hazards) technical textiles with integrated POF sensors, among others sensors are being developed for online structural health monitoring of geotechnical structures. Mechanical deformation in slopes, dams, dikes, embankments and retrofitted masonry structures is to be detected before critical damage occurs. In this paper we present the POF strain sensor properties, reactions to disturbing influences as temperature and bends as well as the results of the different model tests we conducted within POLYTECT. We further show the potential of perfluorinated graded-index POF for distributed strain sensing with increased spatial resolution and measurement lengths.

  6. In-situ measurement of the strain distribution in a tensile specimen by using a digital speckle pattern interferometer

    International Nuclear Information System (INIS)

    Park, Seung-Kyu; Baik, Sung-Hoon; Cha, Hyung-Ki; Kim, Young-Suk; Cheong, Yong-Moo

    2010-01-01

    Less sensitivity to environmental vibrations is essential for industrial applications of a digital speckle pattern interferometer (DSPI) to measure micro deformations. In this paper, a robust DSPI using single fringe to mechanical vibrations is designed for measuring the strain distribution of a tensile specimen. This system adopts a noise-immune signal processing algorithm to acquire a 3D strain distribution image. To acquire an accurate strain distribution for a tensile-specimen, locally-averaged and directionally-oriented filters operating in the frequency domain are used. This system uses a path-independent least-squares phase-unwrapping algorithm to acquire the 3D shape of the strain distribution. As for the initial experiments to measure the strain distribution of a tensile specimen in a vibration field, this system demonstrated a feasibility for industrial applications by providing reliable strain data.

  7. Three-Axis Distributed Fiber Optic Strain Measurement in 3D Woven Composite Structures

    Science.gov (United States)

    Castellucci, Matt; Klute, Sandra; Lally, Evan M.; Froggatt, Mark E.; Lowry, David

    2013-01-01

    Recent advancements in composite materials technologies have broken further from traditional designs and require advanced instrumentation and analysis capabilities. Success or failure is highly dependent on design analysis and manufacturing processes. By monitoring smart structures throughout manufacturing and service life, residual and operational stresses can be assessed and structural integrity maintained. Composite smart structures can be manufactured by integrating fiber optic sensors into existing composite materials processes such as ply layup, filament winding and three-dimensional weaving. In this work optical fiber was integrated into 3D woven composite parts at a commercial woven products manufacturing facility. The fiber was then used to monitor the structures during a VARTM manufacturing process, and subsequent static and dynamic testing. Low cost telecommunications-grade optical fiber acts as the sensor using a high resolution commercial Optical Frequency Domain Reflectometer (OFDR) system providing distributed strain measurement at spatial resolutions as low as 2mm. Strain measurements using the optical fiber sensors are correlated to resistive strain gage measurements during static structural loading. Keywords: fiber optic, distributed strain sensing, Rayleigh scatter, optical frequency domain reflectometry

  8. Distributed Strain Measurement along a Concrete Beam via Stimulated Brillouin Scattering in Optical Fibers

    Directory of Open Access Journals (Sweden)

    Romeo Bernini

    2011-01-01

    Full Text Available The structural strain measurement of tension and compression in a 4 m long concrete beam was demonstrated with a distributed fiber-optic sensor portable system based on Brillouin scattering. Strain measurements provided by the fiber-optic sensor permitted to detect the formation of a crack in the beam resulting from the external applied load. The sensor system is valuable for structural monitoring applications, enabling the long-term performance and health of structures to be efficiently monitored.

  9. Measurement of strain distribution in bonded joints by fiber Bragg gratings

    Science.gov (United States)

    Guemes, J. Alfredo; Diaz-Carrillo, Sebastian; Menendez, Jose M.

    1998-07-01

    Due to the small dimensions of the adhesive layer, the high non-uniformity of the strain field and the non linear elastic behavior of the adhesive material, the strain distribution at an adhesive joint can be predicted by FEM, but can not be experimentally obtained with classical approaches; only non standard procedures like Moire interferometry, or special artifacts like KGR extensometers may afford some insights on the behavior of the adhesive. Due to their small size, ensuring low perturbation of the strain field, and their innate ability to measure strain and strain gradient along the sensor, fiber Bragg gratings offer a good opportunity to solve this problem, and it is a good example of situations that may benefit from these new sensors. Fiber Bragg gratings may be placed or at the interface, within the adhesive layer, or embedded at the adherents, if these were made of composite material. Tests may be run at different temperatures, changing the adhesive characteristics from brittle to pseudoplastic without additional difficulties. When loading the joint, the strain field is obtained by analyzing the distorted spectrum of the reflected light pulse; the algorithm for doing it has already been published. A comparison with theoretical results is done, and the validity and utility of these sensors for this and similar applications is demonstrated.

  10. Self-Evaluation of PANDA-FBG Based Sensing System for Dynamic Distributed Strain and Temperature Measurement.

    Science.gov (United States)

    Zhu, Mengshi; Murayama, Hideaki; Wada, Daichi

    2017-10-12

    A novel method is introduced in this work for effectively evaluating the performance of the PANDA type polarization-maintaining fiber Bragg grating (PANDA-FBG) distributed dynamic strain and temperature sensing system. Conventionally, the errors during the measurement are unknown or evaluated by using other sensors such as strain gauge and thermocouples. This will make the sensing system complicated and decrease the efficiency since more than one kind of sensor is applied for the same measurand. In this study, we used the approximately constant ratio of primary errors in strain and temperature measurement and realized the self-evaluation of the sensing system, which can significantly enhance the applicability, as well as the reliability in strategy making.

  11. Distributed perfluorinated POF strain sensor using OTDR and OFDR techniques

    Science.gov (United States)

    Liehr, Sascha; Wendt, Mario; Krebber, Katerina

    2009-10-01

    This paper presents the latest advances in distributed strain sensing using perfluorinated (PF) polymer optical fibers (POF). Compared to previously introduced PMMA POF strain sensors, PF POF have the advantage of lower loss and therefore extended measurement length of more than 500 m at increased spatial resolution of 10 cm. It is shown that PF POF can measure strain distributed up to 100 %. The characteristic backscatter signature of this fiber type provides additional evaluation possibilities. We show that, by applying a cross-correlation algorithm to the backscatter signal, the distributed length change can be measured along the fiber. We also present, to our knowledge for the first time, incoherent Optical Frequency Domain Reflectometry (OFDR) in POF to measure distributed reflections and loss along the fiber. The OFDR technique proves superior to existing OTDR techniques in measurement speed, resolution and potential instrument costs.

  12. Structural health monitoring of cylindrical bodies under impulsive hydrodynamic loading by distributed FBG strain measurements

    International Nuclear Information System (INIS)

    Fanelli, Pierluigi; Ubertini, Stefano; Biscarini, Chiara; Jannelli, Elio; Ubertini, Filippo

    2017-01-01

    Various mechanical, ocean, aerospace and civil engineering problems involve solid bodies impacting the water surface and often result in complex coupled dynamics, characterized by impulsive loading conditions, high amplitude vibrations and large local deformations. Monitoring in such problems for purposes such as remaining fatigue life estimation and real time damage detection is a technical and scientific challenge of primary concern in this context. Open issues include the need for developing distributed sensing systems able to operate at very high acquisition frequencies, to be utilized to study rapidly varying strain fields, with high resolution and very low noise, while scientific challenges mostly relate to the definition of appropriate signal processing and modeling tools enabling the extraction of useful information from distributed sensing signals. Building on previous work by some of the authors, we propose an enhanced method for real time deformed shape reconstruction using distributed FBG strain measurements in curved bodies subjected to impulsive loading and we establish a new framework for applying this method for structural health monitoring purposes, as the main focus of the work. Experiments are carried out on a cylinder impacting the water at various speeds, proving improved performance in displacement reconstruction of the enhanced method compared to its previous version. A numerical study is then carried out considering the same physical problem with different delamination damages affecting the body. The potential for detecting, localizing and quantifying this damage using the reconstruction algorithm is thoroughly investigated. Overall, the results presented in the paper show the potential of distributed FBG strain measurements for real time structural health monitoring of curved bodies under impulsive hydrodynamic loading, defining damage sensitive features in terms of strain or displacement reconstruction errors at selected locations along

  13. Apodization Optimization of FBG Strain Sensor for Quasi-Distributed Sensing Measurement Applications

    Directory of Open Access Journals (Sweden)

    Fahd Chaoui

    2016-01-01

    Full Text Available A novel optimized apodization of Fiber Bragg Grating Sensor (FBGS for quasi-distributed strain sensing applications is developed and introduced in this paper. The main objective of the proposed optimization is to obtain a reflectivity level higher than 90% and a side lobe level around −40 dB, which is suitable for use in quasi-distributed strain sensing application. For this purpose, different design parameters as apodization profile, grating length, and refractive index have been investigated to enhance and optimize the FBGS design. The performance of the proposed apodization has then been compared in terms of reflectivity, side lobe level (SLL, and full width at half maximum (FWHM with apodization profiles proposed by other authors. The optimized sensor is integrated on quasi-distributed sensing system of 8 sensors demonstrating high reliability. Wide strain sensitivity range for each channel has also been achieved in the quasi-distributed system. Results prove the efficiency of the proposed optimization which can be further implemented for any quasi-distributed sensing application.

  14. Modeling borehole microseismic and strain signals measured by a distributed fiber optic sensor

    Science.gov (United States)

    Mellors, R. J.; Sherman, C. S.; Ryerson, F. J.; Morris, J.; Allen, G. S.; Messerly, M. J.; Carr, T.; Kavousi, P.

    2017-12-01

    The advent of distributed fiber optic sensors installed in boreholes provides a new and data-rich perspective on the subsurface environment. This includes the long-term capability for vertical seismic profiles, monitoring of active borehole processes such as well stimulation, and measuring of microseismic signals. The distributed fiber sensor, which measures strain (or strain-rate), is an active sensor with highest sensitivity parallel to the fiber and subject to varying types of noise, both external and internal. We take a systems approach and include the response of the electronics, fiber/cable, and subsurface to improve interpretation of the signals. This aids in understanding noise sources, assessing error bounds on amplitudes, and developing appropriate algorithms for improving the image. Ultimately, a robust understanding will allow identification of areas for future improvement and possible optimization in fiber and cable design. The subsurface signals are simulated in two ways: 1) a massively parallel multi-physics code that is capable of modeling hydraulic stimulation of heterogeneous reservoir with a pre-existing discrete fracture network, and 2) a parallelized 3D finite difference code for high-frequency seismic signals. Geometry and parameters for the simulations are derived from fiber deployments, including the Marcellus Shale Energy and Environment Laboratory (MSEEL) project in West Virginia. The combination mimics both the low-frequency strain signals generated during the fracture process and high-frequency signals from microseismic and perforation shots. Results are compared with available fiber data and demonstrate that quantitative interpretation of the fiber data provides valuable constraints on the fracture geometry and microseismic activity. These constraints appear difficult, if not impossible, to obtain otherwise.

  15. Qualification of a truly distributed fiber optic technique for strain and temperature measurements in concrete structures

    Science.gov (United States)

    Henault, J. M.; Salin, J.; Moreau, G.; Delepine-Lesoille, S.; Bertand, J.; Taillade, F.; Quiertant, M.; Benzarti, K.

    2011-04-01

    Structural health monitoring is a key factor in life cycle management of infrastructures. Truly distributed fiber optic sensors are able to provide relevant information on large structures, such as nuclear power plants or nuclear waste disposal facilities. The sensing chain includes an optoelectronic unit and a sensing cable made of one or more optical fibers. A new instrument based on Optical Frequency Domain Reflectometry (OFDR), enables to perform temperature and strain measurements with a centimeter scale spatial resolution over hundred of meters and with a level of precision equal to 1 μ strain and 0.1 °C. Several sensing cables are designed with different materials targeting to last for decades, either embedded in the concrete or attached to the surface of the structure. They must ensure an optimal transfer of temperature and strain from the concrete matrix to the optical fiber. Based on the European guide FD CEN/TR 14748 "Non-destructive testing - Methodology for qualification of non-destructive tests", a qualification method was developed. Tests were carried out using various sensing cables embedded in the volume or fixed to the surface of plain concrete specimens and representative-scale reinforced concrete structural elements. Measurements were performed with an OFDR instrument, while mechanical solicitations were imposed to the concrete element. Preliminary experiments seem very promising since measurements performed with distributed sensing systems are found comparable to values obtained with conventional sensors used in civil engineering and with the Strength of Materials Modelling. Moreover, the distributed sensing system makes it possible to detect and localize cracks appearing in concrete during the mechanical loading.

  16. Analysis of strain distribution and critical current of superconductors based on a strain-critical current measurement system

    International Nuclear Information System (INIS)

    Liu Fang; Wu Yu; Long Feng

    2010-01-01

    Based on Pacman device which is widely used to investigate the axial strain dependence of the critical current in superconductors, the finite element analysis method is employed to carry out the force analysis of the spring and the superconducting strand, thereby the axial and lateral strain distributions of the superconducting strand are obtained. According to the two extreme assumptions(low inter-filament resistance and high inter-filament resistance), the effects of the strain homogeneity at the cross section of the superconductor on the critical current is analyzed combined with the Nb 3 Sn deviatoric strain-critical current scaling law. (authors)

  17. Investigation of the interpolation method to improve the distributed strain measurement accuracy in optical frequency domain reflectometry systems.

    Science.gov (United States)

    Cui, Jiwen; Zhao, Shiyuan; Yang, Di; Ding, Zhenyang

    2018-02-20

    We use a spectrum interpolation technique to improve the distributed strain measurement accuracy in a Rayleigh-scatter-based optical frequency domain reflectometry sensing system. We demonstrate that strain accuracy is not limited by the "uncertainty principle" that exists in the time-frequency analysis. Different interpolation methods are investigated and used to improve the accuracy of peak position of the cross-correlation and, therefore, improve the accuracy of the strain. Interpolation implemented by padding zeros on one side of the windowed data in the spatial domain, before the inverse fast Fourier transform, is found to have the best accuracy. Using this method, the strain accuracy and resolution are both improved without decreasing the spatial resolution. The strain of 3 μϵ within the spatial resolution of 1 cm at the position of 21.4 m is distinguished, and the measurement uncertainty is 3.3 μϵ.

  18. Strain measurement on a compact nuclear reactor steam generator

    International Nuclear Information System (INIS)

    Scaldaferri, Denis Henrique Bianchi; Gomes, Paulo de Tarso Vida; Mansur, Tanius Rodrigues; Pozzo, Renato del; Mola, Jairo

    2011-01-01

    This work presents the strain measurement procedures applied to a compact nuclear reactor steam generator, during a hydrostatic test, using strain gage technology. The test was divided in two steps: primary side test and secondary side test. In the primary side test twelve points for strain measurement using rectangular rosettes, three points (two external and one internal) for temperature measurement using special strain gages and one point for pressure measurement using a pressure transducer were monitored. In the secondary side test 18 points for strain measurement using rectangular rosettes, four points (two external and two internal) for temperature measurement using special strain gages and one point for pressure measurement using a pressure transducer were monitored. The measurement points on both internal and external pressurizer walls were established from pre-calculated stress distribution by means of numerical approach (finite elements modeling). Strain values using a quarter Wheatstone bridge circuit were obtained. Stress values, from experimental strain were determined, and to numerical calculation results were compared. (author)

  19. XRD measurement of mean thickness, thickness distribution and strain for illite and illite-smectite crystallites by the Bertaut-Warren-Averbach technique

    Science.gov (United States)

    Drits, Victor A.; Eberl, Dennis D.; Środoń, Jan

    1998-01-01

    A modified version of the Bertaut-Warren-Averbach (BWA) technique (Bertaut 1949, 1950; Warren and Averbach 1950) has been developed to measure coherent scattering domain (CSD) sizes and strains in minerals by analysis of X-ray diffraction (XRD) data. This method is used to measure CSD thickness distributions for calculated and experimental XRD patterns of illites and illite-smectites (I-S). The method almost exactly recovers CSD thickness distributions for calculated illite XRD patterns. Natural I-S samples contain swelling layers that lead to nonperiodic structures in the c* direction and to XRD peaks that are broadened and made asymmetric by mixed layering. Therefore, these peaks cannot be analyzed by the BWA method. These difficulties are overcome by K-saturation and heating prior to X-ray analysis in order to form 10-Å periodic structures. BWA analysis yields the thickness distribution of mixed-layer crystals (coherently diffracting stacks of fundamental illite particles). For most I-S samples, CSD thickness distributions can be approximated by lognormal functions. Mixed-layer crystal mean thickness and expandability then can be used to calculate fundamental illite particle mean thickness. Analyses of the dehydrated, K-saturated samples indicate that basal XRD reflections are broadened by symmetrical strain that may be related to local variations in smectite interlayers caused by dehydration, and that the standard deviation of the strain increases regularly with expandability. The 001 and 002 reflections are affected only slightly by this strain and therefore are suited for CSD thickness analysis. Mean mixed-layer crystal thicknesses for dehydrated I-S measured by the BWA method are very close to those measured by an integral peak width method.

  20. Dynamic strain distribution measurement and crack detection of an adhesive-bonded single-lap joint under cyclic loading using embedded FBG

    International Nuclear Information System (INIS)

    Ning, Xiaoguang; Murayama, Hideaki; Kageyama, Kazuro; Wada, Daichi; Kanai, Makoto; Ohsawa, Isamu; Igawa, Hirotaka

    2014-01-01

    In this study, the dynamic strain distribution measurement of an adhesive-bonded single-lap joint was carried out in a cyclic load test using a fiber Bragg grating (FBG) sensor embedded into the adhesive/adherend interface along the overlap length direction. Unidirectional carbon fiber reinforced plastic (CFRP) substrates were bonded by epoxy resin to form the joint, and the FBG sensor was embedded into the surface of one substrate during its curing. The measurement was carried out with a sampling rate of 5 Hz by the sensing system, based on the optical frequency domain reflectometry (OFDR) throughout the test. A finite element analysis (FEA) was performed for the measurement evaluation using a three-dimensional model, which included the embedded FBG sensor. The crack detection method, based on the longitudinal strain distribution measurement, was introduced and performed to estimate the cracks that occurred at the adhesive/adherend interface in the test. (paper)

  1. Development of a Brillouin scattering based distributed fibre optic strain sensor

    Science.gov (United States)

    Brown, Anthony Wayne

    2001-07-01

    The parameters of the Brillouin spectrum of an optical fibre depend upon the strain and temperature conditions of the fibre. As a result, fibre optic distributed sensors based on Brillouin scattering can measure strain and temperature in arbitrary regions of a sensing fibre. In the past, such sensors have often been demonstrated under laboratory conditions, demonstrating the principle of operation. Although some field tests of temperature sensing have been reported, the actual deployment of such sensors in the field for strain measurements has been limited by poor spatial resolution (typically 1 m or more) and poor strain accuracy (+/-100 muepsilon). Also, cross-sensitivity of the Brillouin spectrum to temperature further reduces the accuracy of strain measurement while long acquisition times hinders field use. The high level of user knowledge and lack of automation required to operate the equipment is another limiting factor of the only commercially available unit. The potential benefits of distributed measurements are great for instrumentation of civil structures provided that the above limitations are overcome. However, before this system is used with confidence by practitioners, it is essential that it can be effectively operated in field conditions. In light of this, the fibre optics group at the University of New Brunswick has been developing an automated system for field measurement of strain in civil structures, particularly in reinforced concrete. The development of the sensing system hardware and software was the main focus of this thesis. This has been made possible, in part, by observation of the Brillouin spectrum for the case of using very short light pulses (performance to measure strain to an accuracy of 10 muepsilon; and allow the simultaneous measurement of strain and temperature to an accuracy of 204 muepsilon and 3°C are presented. Finally, the results of field measurement of strain on a concrete structure are presented.

  2. Strain measurement in a concrete beam by use of the Brillouin-scattering-based distributed fiber sensor with single-mode fibers embedded in glass fiber reinforced polymer rods and bonded to steel reinforcing bars.

    Science.gov (United States)

    Zeng, Xiaodong; Bao, Xiaoyi; Chhoa, Chia Yee; Bremner, Theodore W; Brown, Anthony W; DeMerchant, Michael D; Ferrier, Graham; Kalamkarov, Alexander L; Georgiades, Anastasis V

    2002-08-20

    The strain measurement of a 1.65-m reinforced concrete beam by use of a distributed fiber strain sensor with a 50-cm spatial resolution and 5-cm readout resolution is reported. The strain-measurement accuracy is +/-15 microepsilon (microm/m) according to the system calibration in the laboratory environment with non-uniform-distributed strain and +/-5 microepsilon with uniform strain distribution. The strain distribution has been measured for one-point and two-point loading patterns for optical fibers embedded in pultruded glass fiber reinforced polymer (GFRP) rods and those bonded to steel reinforcing bars. In the one-point loading case, the strain deviations are +/-7 and +/-15 microepsilon for fibers embedded in the GFRP rods and fibers bonded to steel reinforcing bars, respectively, whereas the strain deviation is +/-20 microepsilon for the two-point loading case.

  3. Strain measurement technique

    International Nuclear Information System (INIS)

    1987-01-01

    The 10 contributions are concerned with selected areas of application, such as strain measurements in wood, rubber/metal compounds, sets of strain measurements on buildings, reinforced concrete structures without gaps, pipes buried in the ground and measurements of pressure fluctuations. To increase the availability and safety of plant, stress analyses were made on gas turbine rotors with HT-DMS or capacitive HT-DMS (high temperature strain measurements). (DG) [de

  4. Unsteady Aerodynamic Force Sensing from Measured Strain

    Science.gov (United States)

    Pak, Chan-Gi

    2016-01-01

    A simple approach for computing unsteady aerodynamic forces from simulated measured strain data is proposed in this study. First, the deflection and slope of the structure are computed from the unsteady strain using the two-step approach. Velocities and accelerations of the structure are computed using the autoregressive moving average model, on-line parameter estimator, low-pass filter, and a least-squares curve fitting method together with analytical derivatives with respect to time. Finally, aerodynamic forces over the wing are computed using modal aerodynamic influence coefficient matrices, a rational function approximation, and a time-marching algorithm. A cantilevered rectangular wing built and tested at the NASA Langley Research Center (Hampton, Virginia, USA) in 1959 is used to validate the simple approach. Unsteady aerodynamic forces as well as wing deflections, velocities, accelerations, and strains are computed using the CFL3D computational fluid dynamics (CFD) code and an MSC/NASTRAN code (MSC Software Corporation, Newport Beach, California, USA), and these CFL3D-based results are assumed as measured quantities. Based on the measured strains, wing deflections, velocities, accelerations, and aerodynamic forces are computed using the proposed approach. These computed deflections, velocities, accelerations, and unsteady aerodynamic forces are compared with the CFL3D/NASTRAN-based results. In general, computed aerodynamic forces based on the lifting surface theory in subsonic speeds are in good agreement with the target aerodynamic forces generated using CFL3D code with the Euler equation. Excellent aeroelastic responses are obtained even with unsteady strain data under the signal to noise ratio of -9.8dB. The deflections, velocities, and accelerations at each sensor location are independent of structural and aerodynamic models. Therefore, the distributed strain data together with the current proposed approaches can be used as distributed deflection

  5. Non-Destructive Measurement of Residual Strain in Connecting Rods Using Neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, Tomohiro [Honda R& D; Bunn, Jeffrey R. [ORNL; Fancher, Christopher M. [ORNL; Seid, Alan [Honda R& D; Motani, Ryuta [Honda R& D; Matsuda, Hideki [Honda R& D; Okayama, Tatsuya [Honda R& D

    2018-04-01

    Increasing the strength of materials is effective in reducing weight and boosting structural part performance, but there are cases in where the residual strain generated during the process of manufacturing of high-strength materials results in a decline of durability. It is therefore important to understand how the residual strain in a manufactured component changes due to processing conditions. In the case of a connecting rod, because the strain load on the connecting rod rib sections is high, it is necessary to clearly understand the distribution of strain in the ribs. However, because residual strain is generally measured by using X-ray diffractometers or strain gauges, measurements are limited to the surface layer of the parts. Neutron beams, however, have a higher penetration depth than X-rays, allowing for strain measurement in the bulk material. The research discussed within this paper consists of non-destructive residual strain measurements in the interior of connecting rods using the 2nd Generation Neutron Residual Stress Mapping Facility (NRSF2) at Oak Ridge National Laboratory, measuring the Fe (211) diffraction peak position of the ferrite phase. The interior strain distribution of connecting rod, which prepared under different manufacturing processes, was revealed. By the visualization of interior strains, clear understandings of differences in various processing conditions were obtained. In addition, it is known that the peak width, which is also obtained during measurement, is suggestive of the size of crystallites in the structure; however the peak width can additionally be caused by microstresses and material dislocations.

  6. Application of computer picture processing to dynamic strain measurement under electromagnetic field

    International Nuclear Information System (INIS)

    Yagawa, G.; Soneda, N.

    1987-01-01

    For the structural design of fusion reactors, it is very important to ensure the structural integrity of components under various dynamic loading conditions due to a solid-electromagnetic field interaction, an earthquake, MHD effects and so on. As one of the experimental approaches to assess the dynamic fracture, we consider the strain measurement near a crack tip under a transient electromagnetic field, which in general involves several experimental difficulties. The authors have developed a strain measurement method using a picture processing technique. In this method, locations of marks printed on a surface of specimen are determined by the picture processing. The displacement field is interpolated using the mark displacements and finite elements. Finally the strain distribution is calculated by differentiating the displacement field. In the present study, the method is improved and automated apply to the measurement of dynamic strain distribution under an electromagnetic field. Then the effects of dynamic loading on the strain distribution are investigated by comparing the dynamic results with the static ones. (orig./GL)

  7. The use of pulsed neutron diffraction to measure strain in composites

    International Nuclear Information System (INIS)

    Bourke, M.A.M.; Goldstone, J.A.; Shi, N.; Gray, G.T. III; James, M.R.

    1994-01-01

    Neutron diffraction is a technique for measuring strain in crystalline materials. It is non destructive, phase discriminatory and more penetrating than X rays. Pulsed neutron sources (in contrast with steady state reactor sources) are particularly appropriate for examining heterogeneous materials or for recording the polycrystalline response of all lattice reflections. Several different aspects of composite behavior can be characterized and examples are given of residual strain measurements, strain relaxation during heating, applied loading, and determination of the strain distribution function

  8. Dynamic strain measurement of hydraulic system pipeline using fibre Bragg grating sensors

    Directory of Open Access Journals (Sweden)

    Qiang Wang

    2016-04-01

    Full Text Available Fatigue failure is a serious problem in hydraulic piping systems installed in the machinery and equipment working in harsh operational conditions. To alleviate this problem, health monitoring of pipes can be conducted by measuring and analysing vibration-induced strain. Fibre Bragg grating is considered as a promising sensing approach for dynamic load monitoring. In this article, dynamic strain measurements based on fibre Bragg grating sensors for small-bore metal pipes have been investigated. The quasi-distributed strain sensing of fibre Bragg grating sensors is introduced. Two comparison experiments were carried out under vibration and impact loads among the methods of electrical strain gauge, piezoelectric accelerometer and fibre Bragg grating sensor. Experimental results indicate that fibre Bragg grating sensor possesses an outstanding ability to resist electromagnetic interference compared with strain gauge. The natural frequency measurement results, captured by fibre Bragg grating sensor, agree well with the modal analysis results obtained from finite element analysis. In addition, the attached fibre Bragg grating sensor brings a smaller impact on the dynamic characteristics of the measured pipe than the accelerometer due to its small size and lightweight. Fibre Bragg grating sensors have great potential for the quasi-distributed measurement of dynamic strain for the dynamic characteristic research and health monitoring of hydraulic system pipeline.

  9. Strain measurement based battery testing

    Science.gov (United States)

    Xu, Jeff Qiang; Steiber, Joe; Wall, Craig M.; Smith, Robert; Ng, Cheuk

    2017-05-23

    A method and system for strain-based estimation of the state of health of a battery, from an initial state to an aged state, is provided. A strain gauge is applied to the battery. A first strain measurement is performed on the battery, using the strain gauge, at a selected charge capacity of the battery and at the initial state of the battery. A second strain measurement is performed on the battery, using the strain gauge, at the selected charge capacity of the battery and at the aged state of the battery. The capacity degradation of the battery is estimated as the difference between the first and second strain measurements divided by the first strain measurement.

  10. A three-dimensional strain measurement method in elastic transparent materials using tomographic particle image velocimetry.

    Directory of Open Access Journals (Sweden)

    Azuma Takahashi

    Full Text Available The mechanical interaction between blood vessels and medical devices can induce strains in these vessels. Measuring and understanding these strains is necessary to identify the causes of vascular complications. This study develops a method to measure the three-dimensional (3D distribution of strain using tomographic particle image velocimetry (Tomo-PIV and compares the measurement accuracy with the gauge strain in tensile tests.The test system for measuring 3D strain distribution consists of two cameras, a laser, a universal testing machine, an acrylic chamber with a glycerol water solution for adjusting the refractive index with the silicone, and dumbbell-shaped specimens mixed with fluorescent tracer particles. 3D images of the particles were reconstructed from 2D images using a multiplicative algebraic reconstruction technique (MART and motion tracking enhancement. Distributions of the 3D displacements were calculated using a digital volume correlation. To evaluate the accuracy of the measurement method in terms of particle density and interrogation voxel size, the gauge strain and one of the two cameras for Tomo-PIV were used as a video-extensometer in the tensile test. The results show that the optimal particle density and interrogation voxel size are 0.014 particles per pixel and 40 × 40 × 40 voxels with a 75% overlap. The maximum measurement error was maintained at less than 2.5% in the 4-mm-wide region of the specimen.We successfully developed a method to experimentally measure 3D strain distribution in an elastic silicone material using Tomo-PIV and fluorescent particles. To the best of our knowledge, this is the first report that applies Tomo-PIV to investigate 3D strain measurements in elastic materials with large deformation and validates the measurement accuracy.

  11. Microstructure and strain distribution in freestanding Si membrane strained by Si{sub x}N{sub y} deposition

    Energy Technology Data Exchange (ETDEWEB)

    Gao Hongye, E-mail: qgaohongye@msn.com [Faculty of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Ikeda, Ken-ichi; Hata, Satoshi; Nakashima, Hideharu [Faculty of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Wang Dong; Nakashima, Hiroshi [Art, Science and Technology Center for Cooperative Research, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan)

    2010-09-25

    Research highlights: {yields} Strain is introduced by deposition of amorphous Si{sub x}N{sub y} to improve the carrier mobility for a relatively large-size freestanding semiconductor film, which can be used for the fabrication of relatively large devices such like a bipolar junction transistor. However, standard Raman spectroscopy and X-ray diffraction cannot provide sufficient lateral resolution to the strain in a relatively long (x {mu}m in length) and thin (x nm in thickness) freestanding semiconductor film. {yields} In present research, strain in a bridge-shaped freestanding Si membrane (FSSM) was measured by convergent-beam electron diffraction (CBED) and finite element method (FEM). Compressive strain distribution was shown in three dimensions (3D) in FSSM, where no threading dislocation or stacking fault was found. Relaxation of the strain in FSSM in 3D was discussed based on a comparison of the strain magnitudes in FSSM as measured by CBED and FEM. - Abstract: Strain in a bridge-shaped freestanding Si membrane (FSSM) induced by depositing an amorphous Si{sub x}N{sub y} layer was measured by convergent-beam electron diffraction (CBED). CBED results show that the strain magnitude depends negatively on the FSSM thickness. FEM is a supplement of the result of CBED due to the relaxation of TEM samples during fabricating. The FEM analysis results ascertain the strain property in three dimensions, and show that the strain magnitude depends negatively on the length of FSSM, and the magnitude of the compressive strain in FSSM increases as the position is closer to the upper Si/Si{sub x}N{sub y} interface.

  12. Industrial Qualification Process for Optical Fibers Distributed Strain and Temperature Sensing in Nuclear Waste Repositories

    Directory of Open Access Journals (Sweden)

    S. Delepine-Lesoille

    2012-01-01

    Full Text Available Temperature and strain monitoring will be implemented in the envisioned French geological repository for high- and intermediate-level long-lived nuclear wastes. Raman and Brillouin scatterings in optical fibers are efficient industrial methods to provide distributed temperature and strain measurements. Gamma radiation and hydrogen release from nuclear wastes can however affect the measurements. An industrial qualification process is successfully proposed and implemented. Induced measurement uncertainties and their physical origins are quantified. The optical fiber composition influence is assessed. Based on radiation-hard fibers and carbon-primary coatings, we showed that the proposed system can provide accurate temperature and strain measurements up to 0.5 MGy and 100% hydrogen concentration in the atmosphere, over 200 m distance range. The selected system was successfully implemented in the Andra underground laboratory, in one-to-one scale mockup of future cells, into concrete liners. We demonstrated the efficiency of simultaneous Raman and Brillouin scattering measurements to provide both strain and temperature distributed measurements. We showed that 1.3 μm working wavelength is in favor of hazardous environment monitoring.

  13. Reliability Assessment for PSC Box-Girder Bridges Based on SHM Strain Measurements

    Directory of Open Access Journals (Sweden)

    Chuang Chen

    2017-01-01

    Full Text Available A reliability assessment method for prestressed concrete (PSC continuous box-girder bridges based on structural health monitoring (SHM strain measurements was proposed. First, due to the fact that measured strain was compositive and the variation periods of its components were different, a series of limit state equations under normal use limit state were given. Then, a linear fitting method was used to determine the relationship between the ambient temperature and the measured strain, which was aimed at extracting the vehicle load effect and the temperature load effect from the measured strain. Finally, according to the equivalent normalization method, the load effects unsatisfying the normal distribution by probability density function fitting were transformed, and the daily failure probabilities of monitored positions were calculated for evaluating the safety state of the girder. The results show that (1 the top plate of the box girder is more sensitive than the bottom plate to the high temperature, (2 the daily and seasonal strain variations induced by uniform temperature reveal an inconsistent tendency to the seasonal variation for mid-span cross sections, and (3 the generalized extreme value distribution is recommended for temperature gradient stress and vehicle induced stress fitting for box-girder bridges.

  14. Strain distributions and their influence on electronic structures of WSe2-MoS2 laterally strained heterojunctions

    Science.gov (United States)

    Zhang, Chendong; Li, Ming-Yang; Tersoff, Jerry; Han, Yimo; Su, Yushan; Li, Lain-Jong; Muller, David A.; Shih, Chih-Kang

    2018-02-01

    Monolayer transition metal dichalcogenide heterojunctions, including vertical and lateral p-n junctions, have attracted considerable attention due to their potential applications in electronics and optoelectronics. Lattice-misfit strain in atomically abrupt lateral heterojunctions, such as WSe2-MoS2, offers a new band-engineering strategy for tailoring their electronic properties. However, this approach requires an understanding of the strain distribution and its effect on band alignment. Here, we study a WSe2-MoS2 lateral heterojunction using scanning tunnelling microscopy and image its moiré pattern to map the full two-dimensional strain tensor with high spatial resolution. Using scanning tunnelling spectroscopy, we measure both the strain and the band alignment of the WSe2-MoS2 lateral heterojunction. We find that the misfit strain induces type II to type I band alignment transformation. Scanning transmission electron microscopy reveals the dislocations at the interface that partially relieve the strain. Finally, we observe a distinctive electronic structure at the interface due to hetero-bonding.

  15. Discussion on accuracy of weld residual stress measurement by neutron diffraction. Influence of strain free reference

    International Nuclear Information System (INIS)

    Suzuki, Hiroshi; Akita, Koichi

    2012-01-01

    It is required to evaluate a strain-free reference, α 0 , to perform accurate stress measurement using neutron diffraction. In this study, accuracy of neutron stress measurement was quantitatively discussed from α 0 evaluations on a dissimilar metal butt-weld between a type 304 austenitic stainless steel and an A533B low alloy ferritic steel. A strain-free standard specimen and a sliced specimen with 10 mm thickness taken from the dissimilar metal butt-weld were utilized. In the lattice constant evaluation using the standard specimen, average lattice constant derived from multiple hkl reflections was evaluated as the stress-free reference with cancelling out an intergranular strain. Comparing lattice constant distributions in each reflection with average lattice constant distribution in the standard specimen, αFe211 and γFe311 reflections were judged as a suitable reflection for neutron strain measurement to reduce intergranular strain effects. Residual stress distribution in the sliced specimen evaluated using α 0 measured here exhibited higher accuracy than that measured using strain gauges. On the other hand, α 0 distributions were evaluated using the sliced specimen under the plane-stress condition. Existence of slight longitudinal residual stresses near the weld center decreased accuracy of the α 0 evaluations, which means that it is required to optimize the thickness of the sliced specimen for accurate α 0 evaluation under plane strain condition. As a conclusion of this study, it was confirmed that procedures of accurate α 0 evaluation, optimization of the measurement condition, and multiple evaluations on the results play an important role to improve accuracy of the residual stress measurement using neutron diffraction. (author)

  16. Impact of measurement uncertainty from experimental load distribution factors on bridge load rating

    Science.gov (United States)

    Gangone, Michael V.; Whelan, Matthew J.

    2018-03-01

    Load rating and testing of highway bridges is important in determining the capacity of the structure. Experimental load rating utilizes strain transducers placed at critical locations of the superstructure to measure normal strains. These strains are then used in computing diagnostic performance measures (neutral axis of bending, load distribution factor) and ultimately a load rating. However, it has been shown that experimentally obtained strain measurements contain uncertainties associated with the accuracy and precision of the sensor and sensing system. These uncertainties propagate through to the diagnostic indicators that in turn transmit into the load rating calculation. This paper will analyze the effect that measurement uncertainties have on the experimental load rating results of a 3 span multi-girder/stringer steel and concrete bridge. The focus of this paper will be limited to the uncertainty associated with the experimental distribution factor estimate. For the testing discussed, strain readings were gathered at the midspan of each span of both exterior girders and the center girder. Test vehicles of known weight were positioned at specified locations on each span to generate maximum strain response for each of the five girders. The strain uncertainties were used in conjunction with a propagation formula developed by the authors to determine the standard uncertainty in the distribution factor estimates. This distribution factor uncertainty is then introduced into the load rating computation to determine the possible range of the load rating. The results show the importance of understanding measurement uncertainty in experimental load testing.

  17. Novel distributed strain sensing in polymeric materials

    International Nuclear Information System (INIS)

    Abot, Jandro L; Song, Yi; Medikonda, Sandeep; Rooy, Nathan; Schulz, Mark J

    2010-01-01

    Monitoring the state of strain throughout an entire structure is essential to determine its state of stress, detect potential residual stresses after fabrication, and also to help to establish its integrity. Several sensing technologies are presently available to determine the strain in the surface or inside a structure. Large sensor dimensions, complex signal conditioning equipment, and difficulty in achieving a widely distributed system have however hindered their development into robust structural health monitoring techniques. Recently, carbon nanotube forests were spun into a microscale thread that is electrically conductive, tough, and easily tailorable. The thread was integrated into polymeric materials and used for the first time as a piezoresistive sensor to monitor strain and also to detect damage in the material. It is revealed that the created self-sensing polymeric materials are sensitive to normal strains above 0.07% and that the sensor thread exhibits a perfectly linear delta resistance–strain response above 0.3%. The longitudinal gauge factors were determined to be in the 2–5 range. This low cost and simple built-in sensor thread may provide a new integrated and distributed sensor technology that enables robust real-time health monitoring of structures

  18. Validation Tests of Fiber Optic Strain-Based Operational Shape and Load Measurements

    Science.gov (United States)

    Bakalyar, John A.; Jutte, Christine

    2012-01-01

    Aircraft design has been progressing toward reduced structural weight to improve fuel efficiency, increase performance, and reduce cost. Lightweight aircraft structures are more flexible than conventional designs and require new design considerations. Intelligent sensing allows for enhanced control and monitoring of aircraft, which enables increased structurally efficiency. The NASA Dryden Flight Research Center (DFRC) has developed an instrumentation system and analysis techniques that combine to make distributed structural measurements practical for lightweight vehicles. Dryden's Fiber Optic Strain Sensing (FOSS) technology enables a multitude of lightweight, distributed surface strain measurements. The analysis techniques, referred to as the Displacement Transfer Functions (DTF) and Load Transfer Functions (LTF), use surface strain values to calculate structural deflections and operational loads. The combined system is useful for real-time monitoring of aeroelastic structures, along with many other applications. This paper describes how the capabilities of the measurement system were demonstrated using subscale test articles that represent simple aircraft structures. Empirical FOSS strain data were used within the DTF to calculate the displacement of the article and within the LTF to calculate bending moments due to loads acting on the article. The results of the tests, accuracy of the measurements, and a sensitivity analysis are presented.

  19. Effect of epoxy impregnation on strain distribution of materials in Bi2223 superconducting coils by using synchrotron X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Xinzhe, E-mail: xinzhe.jin@riken.jp [Center for Life Science Technologies, RIKEN, Yokohama-shi, Kanagawa 230-0045 (Japan); Osamura, Kozo [Research Institute for Applied Sciences, Sakyo-ku, Kyoto 606-8202 (Japan); Machiya, Shutaro [Daido University, Minami-ku, Nagoya 457-8530 (Japan); Kajiwara, Kentaro [Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5198 (Japan); Shobu, Takahisa [Japan Atomic Energy Agency, Sayo, Hyogo 679-5148 (Japan); Maeda, Hideaki [Center for Life Science Technologies, RIKEN, Yokohama-shi, Kanagawa 230-0045 (Japan)

    2015-11-25

    Synchrotron X-rays have been used to observe strain distributions in composite materials such as superconducting wires with a thickness of less than about 2 mm. In applications that employ wound coils of superconducting wire, it is necessary to understand the strain distribution within the coiled wire. Superconducting wires such as Bi2223 and REBCO wires approximately 4–5 mm wide are commercially available. Coiled wires of this width are too thick to easily measure using conventional X-ray techniques, especially the inner strain, because the penetration depth tends to be around 2 mm. Therefore, the beam penetration must be improved, and it is known that the penetration depth of an X-ray beam depends upon the beam energy, beam intensity, measurement material, and measurement method. In this study, we used a white X-ray diffractometer at SPring-8 to develop a method of observing the strain distribution in Bi2223 superconducting coils winded by a 4.5 mm wide Bi2223 wire. We successfully observed a clear (400) peak of the Bi2223 phase by an appropriate measurement condition, and then observed the strains of each material in the Bi2223 coils with and without epoxy impregnation. This is the first time that we have obtained the strain of a Bi2223 phase in coiled wire using synchrotron X-ray diffraction. Further synchrotron-based study of superconducting coils will be useful in the development of advanced high-field magnets. The appropriate measurement method and the obtained measurement results are presented in this paper. - Highlights: • We successfully obtained clear peaks of Bi2223 phase in 4.5 mm thick coils. • The strain behaviors of materials in the coil correspond to a three turn cycle model. • A uniform strain distribution of the Bi2223 phase was obtained by epoxy impregnation.

  20. Strain distributions and their influence on electronic structures of WSe2–MoS2 laterally strained heterojunctions

    KAUST Repository

    Zhang, Chendong

    2018-01-12

    Monolayer transition metal dichalcogenide heterojunctions, including vertical and lateral p–n junctions, have attracted considerable attention due to their potential applications in electronics and optoelectronics. Lattice-misfit strain in atomically abrupt lateral heterojunctions, such as WSe2–MoS2, offers a new band-engineering strategy for tailoring their electronic properties. However, this approach requires an understanding of the strain distribution and its effect on band alignment. Here, we study a WSe2–MoS2 lateral heterojunction using scanning tunnelling microscopy and image its moiré pattern to map the full two-dimensional strain tensor with high spatial resolution. Using scanning tunnelling spectroscopy, we measure both the strain and the band alignment of the WSe2–MoS2 lateral heterojunction. We find that the misfit strain induces type II to type I band alignment transformation. Scanning transmission electron microscopy reveals the dislocations at the interface that partially relieve the strain. Finally, we observe a distinctive electronic structure at the interface due to hetero-bonding.

  1. Strain distributions and their influence on electronic structures of WSe2–MoS2 laterally strained heterojunctions

    KAUST Repository

    Zhang, Chendong; Li, Ming-yang; Tersoff, Jerry; Han, Yimo; Su, Yushan; Li, Lain-Jong; Muller, David A.; Shih, Chih-Kang

    2018-01-01

    Monolayer transition metal dichalcogenide heterojunctions, including vertical and lateral p–n junctions, have attracted considerable attention due to their potential applications in electronics and optoelectronics. Lattice-misfit strain in atomically abrupt lateral heterojunctions, such as WSe2–MoS2, offers a new band-engineering strategy for tailoring their electronic properties. However, this approach requires an understanding of the strain distribution and its effect on band alignment. Here, we study a WSe2–MoS2 lateral heterojunction using scanning tunnelling microscopy and image its moiré pattern to map the full two-dimensional strain tensor with high spatial resolution. Using scanning tunnelling spectroscopy, we measure both the strain and the band alignment of the WSe2–MoS2 lateral heterojunction. We find that the misfit strain induces type II to type I band alignment transformation. Scanning transmission electron microscopy reveals the dislocations at the interface that partially relieve the strain. Finally, we observe a distinctive electronic structure at the interface due to hetero-bonding.

  2. Distributed Temperature and Strain Discrimination with Stimulated Brillouin Scattering and Rayleigh Backscatter in an Optical Fiber

    Directory of Open Access Journals (Sweden)

    Xiaoyi Bao

    2013-01-01

    Full Text Available A distributed optical fiber sensor with the capability of simultaneously measuring temperature and strain is proposed using a large effective area non-zero dispersion shifted fiber (LEAF with sub-meter spatial resolution. The Brillouin frequency shift is measured using Brillouin optical time-domain analysis (BOTDA with differential pulse-width pair technique, while the spectrum shift of the Rayleigh backscatter is measured using optical frequency-domain reflectometry (OFDR. These shifts are the functions of both temperature and strain, and can be used as two independent parameters for the discrimination of temperature and strain. A 92 m measurable range with the spatial resolution of 50 cm is demonstrated experimentally, and accuracies of ±1.2 °C in temperature and ±15 με in strain could be achieved.

  3. Measurement of in-plane strain with dual beam spatial phase-shift digital shearography

    International Nuclear Information System (INIS)

    Xie, Xin; Chen, Xu; Li, Junrui; Yang, Lianxiang; Wang, Yonghong

    2015-01-01

    Full-field in-plane strain measurement under dynamic loading by digital shearography remains a big challenge in practice. A phase measurement for in-plane strain information within one time frame has to be achieved to solve this problem. This paper presents a dual beam spatial phase-shift digital shearography system with the capacity to measure phase distribution corresponding to in-plane strain information within a single time frame. Two laser beams with different wavelengths are symmetrically arranged to illuminate the object under test, and two cameras with corresponding filters, which enable simultaneous recording of two shearograms, are utilized for data acquisition. The phase information from the recorded shearograms, which corresponds to the in-plane strain, is evaluated by the spatial phase-shift method. The spatial phase-shift shearography system realizes a measurement of the in-plane strain through the introduction of the spatial phase-shift technique, using one frame after the loading and one frame before loading. This paper presents the theory of the spatial phase-shift digital shearography for in-plane strain measurement and its derivation, experimental results, and the technique’s potential. (paper)

  4. Research on the novel FBG detection system for temperature and strain field distribution

    Science.gov (United States)

    Liu, Zhi-chao; Yang, Jin-hua

    2017-10-01

    In order to collect the information of temperature and strain field distribution information, the novel FBG detection system was designed. The system applied linear chirped FBG structure for large bandwidth. The structure of novel FBG cover was designed as a linear change in thickness, in order to have a different response at different locations. It can obtain the temperature and strain field distribution information by reflection spectrum simultaneously. The structure of novel FBG cover was designed, and its theoretical function is calculated. Its solution is derived for strain field distribution. By simulation analysis the change trend of temperature and strain field distribution were analyzed in the conditions of different strain strength and action position, the strain field distribution can be resolved. The FOB100 series equipment was used to test the temperature in experiment, and The JSM-A10 series equipment was used to test the strain field distribution in experiment. The average error of experimental results was better than 1.1% for temperature, and the average error of experimental results was better than 1.3% for strain. There were individual errors when the strain was small in test data. It is feasibility by theoretical analysis, simulation calculation and experiment, and it is very suitable for application practice.

  5. Fabrication and evaluation of hybrid silica/polymer optical fiber sensors for large strain measurement

    Science.gov (United States)

    Huang, Haiying

    2007-04-01

    Silica-based optical fiber sensors are widely used in structural health monitoring systems for strain and deflection measurement. One drawback of silica-based optical fiber sensors is their low strain toughness. In general, silica-based optical fiber sensors can only reliably measure strains up to 2%. Recently, polymer optical fiber sensors have been employed to measure large strain and deflection. Due to their high optical losses, the length of the polymer optical fibers is limited to 100 meters. In this paper, we present a novel economical technique to fabricate hybrid silica/polymer optical fiber strain sensors for large strain measurement. First, stress analysis of a surface-mounted optical fiber sensor is performed to understand the load distribution between the host structure and the optical fiber in relation to their mechanical properties. Next, the procedure of fabricating a polymer sensing element between two optical fibers is explained. The experimental set-up and the components used in the fabrication process are described in details. Mechanical testing results of the fabricated silica/polymer optical fiber strain sensor are presented.

  6. Inverse calculation of strain profiles from ETDR measurements using artificial neural networks

    Directory of Open Access Journals (Sweden)

    R. Höhne

    2017-12-01

    Full Text Available A novel carbon fibre sensor is developed for the spatially resolved strain measurement. A unique feature of the sensor is the fibre-break resistive measurement principle and the two-core transmission line design. The electrical time domain reflectometry (ETDR is used in order to realize a spatially resolved measurement of the electrical parameters of the sensor. In this contribution, the process of mapping between the ETDR signals to the existing strain profile is described. Artificial neural networks (ANNs are used to solve the inverse electromagnetic problem. The investigations were carried out with a sensor patch in a cantilever arm configuration. Overall, 136 experiments with varying strain distribution over the sensor length were performed to generate the necessary training data to learn the ANN model. The validation of the ANN highlights the feasibility as well as the current limits concerning the quantitative accuracy of mapping ETDR signals to strain profiles.

  7. Effects of gauge volume on pseudo-strain induced in strain measurement using time-of-flight neutron diffraction

    International Nuclear Information System (INIS)

    Suzuki, Hiroshi; Harjo, Stefanus; Abe, Jun; Xu, Pingguang; Aizawa, Kazuya; Akita, Koichi

    2013-01-01

    Spurious or pseudo-strains observed in time-of-flight (TOF) neutron diffraction due to neutron attenuation, surface-effects and a strain distribution within the gauge volume were investigated. Experiments were carried out on annealed and bent ferritic steel bars to test these effects. The most representative position in the gauge volume corresponds to the neutron-weighted center of gravity (ncog), which takes into account variations in intensity within the gauge volume due to neutron attenuation and/or absence of material in the gauge volume. The average strain in the gauge volume was observed to be weighted towards the ncog position but following an increase in the size of the gauge volume the weighted average strain was changed because of the change in the ncog position when a strain gradient appeared within the gauge volume. On the other hand, typical pseudo-strains, which are well known, did appear in through-surface strain measurements when the gauge volume was incompletely filled by the sample. Tensile pseudo-strains due to the surface-effect increased near the sample surface and exhibited a similar trend regardless of the size of the gauge volume, while the pseudo-strains increased faster for the smaller gauge volume. Furthermore, a pseudo-strain due to a change in the ncog position was observed even when the gauge volume was perfectly filled in the sample, and it increased with an increase in the size of the gauge volume. These pseudo-strains measured were much larger than those simulated by the conventional modeling, whereas they were simulated by taking into account an incident neutron beam divergence additionally in the model. Therefore, the incident divergence of the incident neutron beam must be carefully designed to avoid pseudo-strains in time-of-flight neutron diffractometry

  8. Experimental strain modal analysis for beam-like structure by using distributed fiber optics and its damage detection

    Science.gov (United States)

    Cheng, Liangliang; Busca, Giorgio; Cigada, Alfredo

    2017-07-01

    Modal analysis is commonly considered as an effective tool to obtain the intrinsic characteristics of structures including natural frequencies, modal damping ratios, and mode shapes, which are significant indicators for monitoring the health status of engineering structures. The complex mode indicator function (CMIF) can be regarded as an effective numerical tool to perform modal analysis. In this paper, experimental strain modal analysis based on the CMIF has been introduced. Moreover, a distributed fiber-optic sensor, as a dense measuring device, has been applied to acquire strain data along a beam surface. Thanks to the dense spatial resolution of the distributed fiber optics, more detailed mode shapes could be obtained. In order to test the effectiveness of the method, a mass lump—considered as a linear damage component—has been attached to the surface of the beam, and damage detection based on strain mode shape has been carried out. The results manifest that strain modal parameters can be estimated effectively by utilizing the CMIF based on the corresponding simulations and experiments. Furthermore, damage detection based on strain mode shapes benefits from the accuracy of strain mode shape recognition and the excellent performance of the distributed fiber optics.

  9. Response of a uniform optical fiber Bragg grating to strain with a non-smooth distribution: measurements and simulations

    Science.gov (United States)

    Detka, Małgorzata

    2017-08-01

    The paper presents results of numerical analyses of the response of a uniform fiber Bragg grating subjected to a strain with non-smooth profile. Results of measurements of the response of the grating to a compressive strain correspond well with results of the simulation and show, that the induced strain profile of the grating causes a widening of its reflection spectrum with a considerable shape irregularity, dependent on the location of the point where slope of the strain profile changes abruptly, and on the maximum value of the strain.

  10. Processing and Characterization of a Novel Distributed Strain Sensor Using Carbon Nanotube-Based Nonwoven Composites

    Directory of Open Access Journals (Sweden)

    Hongbo Dai

    2015-07-01

    Full Text Available This paper describes the development of an innovative carbon nanotube-based non-woven composite sensor that can be tailored for strain sensing properties and potentially offers a reliable and cost-effective sensing option for structural health monitoring (SHM. This novel strain sensor is fabricated using a readily scalable process of coating Carbon nanotubes (CNT onto a nonwoven carrier fabric to form an electrically-isotropic conductive network. Epoxy is then infused into the CNT-modified fabric to form a free-standing nanocomposite strain sensor. By measuring the changes in the electrical properties of the sensing composite the deformation can be measured in real-time. The sensors are repeatable and linear up to 0.4% strain. Highest elastic strain gage factors of 1.9 and 4.0 have been achieved in the longitudinal and transverse direction, respectively. Although the longitudinal gage factor of the newly formed nanocomposite sensor is close to some metallic foil strain gages, the proposed sensing methodology offers spatial coverage, manufacturing customizability, distributed sensing capability as well as transverse sensitivity.

  11. Methodology to measure strains at high temperatures using electrical strain gages with free filaments

    International Nuclear Information System (INIS)

    Atanazio Filho, Nelson N.; Gomes, Paulo T. Vida; Scaldaferri, Denis H.B.; Silva, Luiz L. da; Rabello, Emerson G.; Mansur, Tanius R.

    2013-01-01

    An experimental methodology used for strains measuring at high temperatures is show in this work. In order to do the measurements, it was used electric strain gages with loose filaments attached to a stainless steel 304 beam with specific cements. The beam has triangular shape and a constant thickness, so the strain is the same along its length. Unless the beam surface be carefully prepared, the strain gage attachment is not efficient. The showed results are for temperatures ranging from 20 deg C to 300 deg C, but the experimental methodology could be used to measure strains at a temperature up to 900 deg C. Analytical calculations based on solid mechanics were used to verify the strain gage electrical installation and the measured strains. At a first moment, beam deformations as a temperature function were plotted. After that, beam deformations with different weighs were plotted as a temperature function. The results shown allowed concluding that the experimental methodology is trustable to measure strains at temperatures up to 300 deg C. (author)

  12. Instrument for measuring fuel cladding strain

    International Nuclear Information System (INIS)

    Billeter, T.R.

    1976-01-01

    Development work to provide instrumentation for the continuous measurement of strain of material specimens such as nuclear fuel cladding has shown that a microwave sensor and associated instrumentation hold promise. The cylindrical sensor body enclosing the specimen results in a coaxial resonator absorbing microwave energy at frequencies dependent upon the diameter of the specimen. Diametral changes of a microinch can be resolved with use of the instrumentation. Very reasonable values of elastic strain were measured at 75 0 F and 1000 0 F for an internally pressurized 20 percent C.W. 316 stainless steel specimen simulating nuclear fuel cladding. The instrument also indicated the creep strain of the same specimen pressurized at 6500 psi and at a temperature of 1000 0 F for a period of 700 hours. Although the indicated strain appears greater than actual, the sensor/specimen unit experienced considerable oxidation even though an inert gas purge persisted throughout the test duration. By monitoring at least two modes of resonance, the measured strain was shown to be nearly independent of sensor temperature. To prevent oxidation, a second test was performed in which the specimen/sensor units were contained in an evacuated enclosure. The strain of the two prepressurized specimens as indicated by the microwave instrumentation agreed very closely with pre- and post-test measurements obtained with use of a laser interferometer

  13. Effect of different strain distributions on the phase transformations in steel. Einfluss verschiedener Dehnungszustaende auf das Umwandlungsverhalten eines Stahls

    Energy Technology Data Exchange (ETDEWEB)

    Lyra, A.; Dahl, W. (Technische Hochschule Aachen (Germany, F.R.). Inst. fuer Eisenhuettenkunde)

    1990-01-01

    Using tensile specimens with two different geometries (notched and unnotched) and five cooling rates the anisothermal phase transformation of a 100 Cr 6 steel has been investigated under influence of different strain distributions inside the specimens. The nonhomogeneous distribution of plastic strain has been achieved by tensile testing at high temperatures (800deg C). Measurement of the transformation temperatures was carried out by dilatometry and differential thermal analysis (DTA). The results reveal that due to hot deformation the pearlitic transformation curves in the CCT-Diagram are dislocated to shorter times and higher temperatures compared with the underformed state. The extent of the displacement is however a function of the strain distribution inside the specimens. (orig.).

  14. Synchrotron measurements of local microstructure and residual strains in ductile cast iron

    DEFF Research Database (Denmark)

    Zhang, Yubin; Andriollo, Tito; Fæster, Søren

    2017-01-01

    The local microstructure and distribution of thermally induced residual strains in ferrite matrix grains around an individual spherical graphite nodule in ductile cast iron (DCI) were measured using a synchrotron X-ray micro-diffraction technique. It is found that the matrix grains are deformed...

  15. An Approach for the Dynamic Measurement of Ring Gear Strains of Planetary Gearboxes Using Fiber Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Hang Niu

    2017-12-01

    Full Text Available The strain of the ring gear can reflect the dynamic characteristics of planetary gearboxes directly, which makes it an ideal signal to monitor the health condition of the gearbox. To overcome the disadvantages of traditional methods, a new approach for the dynamic measurement of ring gear strains using fiber Bragg gratings (FBGs is proposed in this paper. Firstly, the installation of FBGs is determined according to the analysis for the strain distribution of the ring gear. Secondly, the parameters of the FBG are determined in consideration of the accuracy and sensitivity of the measurement as well as the size of the ring gear. The strain measured by the FBG is then simulated under non-uniform strain field conditions. Thirdly, a dynamic measurement system is built and tested. Finally, the strains of the ring gear are measured in a planetary gearbox under normal and faulty conditions. The experimental results showed good agreement with the theoretical results in values, trends, and the fault features can be seen from the time domain of the measured strain signal, which proves that the proposed method is feasible for the measurement of the ring gear strains of planetary gearboxes.

  16. An Approach for the Dynamic Measurement of Ring Gear Strains of Planetary Gearboxes Using Fiber Bragg Gratings.

    Science.gov (United States)

    Niu, Hang; Zhang, Xiaodong; Hou, Chenggang

    2017-12-16

    The strain of the ring gear can reflect the dynamic characteristics of planetary gearboxes directly, which makes it an ideal signal to monitor the health condition of the gearbox. To overcome the disadvantages of traditional methods, a new approach for the dynamic measurement of ring gear strains using fiber Bragg gratings (FBGs) is proposed in this paper. Firstly, the installation of FBGs is determined according to the analysis for the strain distribution of the ring gear. Secondly, the parameters of the FBG are determined in consideration of the accuracy and sensitivity of the measurement as well as the size of the ring gear. The strain measured by the FBG is then simulated under non-uniform strain field conditions. Thirdly, a dynamic measurement system is built and tested. Finally, the strains of the ring gear are measured in a planetary gearbox under normal and faulty conditions. The experimental results showed good agreement with the theoretical results in values, trends, and the fault features can be seen from the time domain of the measured strain signal, which proves that the proposed method is feasible for the measurement of the ring gear strains of planetary gearboxes.

  17. Stress Measurement around a Circular Role in a Cantilever Beam under Bending Moment Using Strain Gage and Reflective Photoelasticity

    Energy Technology Data Exchange (ETDEWEB)

    Baek, Tae Hyun; Park, Tae Geun; Yang, Min Bok [Kunsan National University, Gunsan (Korea, Republic of)

    2006-10-15

    It is necessary to study on the stress concentration experimentally, which is the main reason to avoid mechanical dilapidation and failure, when designing a mechanical structure. Stress concentration factor of a specimen of cantilever beam with a circular hole in the center was measured using both strain gage and photoelastic methods in this paper. In strain-gage measurement, three strain gages along the line near a hole of the specimen were installed and maximum strain was extrapolated from three measurements. In photoelastic measurement, two methods were employed. First, the Babinet-Soleil compensation method was used to measure the maximum strain. Secondly, photoelastic 4-step phase shilling method was applied to observe the strain distribution around the hole. Measurements obtained by different experiments were comparable within the range of experimental error

  18. Stress Measurement around a Circular Role in a Cantilever Beam under Bending Moment Using Strain Gage and Reflective Photoelasticity

    International Nuclear Information System (INIS)

    Baek, Tae Hyun; Park, Tae Geun; Yang, Min Bok

    2006-01-01

    It is necessary to study on the stress concentration experimentally, which is the main reason to avoid mechanical dilapidation and failure, when designing a mechanical structure. Stress concentration factor of a specimen of cantilever beam with a circular hole in the center was measured using both strain gage and photoelastic methods in this paper. In strain-gage measurement, three strain gages along the line near a hole of the specimen were installed and maximum strain was extrapolated from three measurements. In photoelastic measurement, two methods were employed. First, the Babinet-Soleil compensation method was used to measure the maximum strain. Secondly, photoelastic 4-step phase shilling method was applied to observe the strain distribution around the hole. Measurements obtained by different experiments were comparable within the range of experimental error

  19. Thermal strain measurement of EAST W/Cu divertor structure using electric resistance strain gauges

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xingli [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Science Island Branch of Graduate School, University of Science & Technology of China, Hefei, 230031 (China); Wang, Wanjing, E-mail: wjwang@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Wang, Jichao [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Wei, Ran; Sun, Zhaoxuan [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Science Island Branch of Graduate School, University of Science & Technology of China, Hefei, 230031 (China); Li, Qiang; Xie, Chunyi [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Chen, Hong-En; Wang, Kaiqiang; Wu, Lei; Chen, Zhenmao [State Key Lab for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University (China); Luo, Guang-Nan [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Science Island Branch of Graduate School, University of Science & Technology of China, Hefei, 230031 (China); Hefei Center for Physical Science and Technology, Hefei, 230022 (China); Hefei Science Center of Chinese Academy of Sciences, Hefei, 230027 (China)

    2016-12-15

    Highlights: • To understand the service behavior of W/Cu divertor, an electrical resistance strain gauge system had been introduced in a thermal strain measurement experiment. • The measurement system successfully finished the experiment and obtained valued thermal strain data. • Two thermomechanical analyses had also been carried out and compared with the measurement results. • Experiment results corresponded well to simulations and threw a light upon the failure of W/Cu divertor in the previous baking tests. - Abstract: W/Cu divertor has complex structure and faces extreme work environment in EAST Tokamak device. To measure its thermal strain shall be a valued way to understand its service behavior and then optimize its design and manufacturing process. This work presents a preliminary study on measuring thermal strain of EAST W/Cu divertor structure using electric resistance strain gauges. Eight gauges had been used in the experiment and the heating temperature had been set to 230 °C with respect to the work temperature. To realize the measuring experiment, an appropriate fixing method of gauges in divertor narrow spaces had been taken and tested, which could not only withstand high temperature but also had no damage to the divertor sample. The measurement results were that three gauges showed positive strain while other three showed negative strain after having been compensated, which corresponded to tensile stress and compressed stress respectively. Two thermomechanical simulations had also been carried out and used for comparing with the experiment.

  20. Different distribution patterns of ten virulence genes in Legionella reference strains and strains isolated from environmental water and patients.

    Science.gov (United States)

    Zhan, Xiao-Yong; Hu, Chao-Hui; Zhu, Qing-Yi

    2016-04-01

    Virulence genes are distinct regions of DNA which are present in the genome of pathogenic bacteria and absent in nonpathogenic strains of the same or related species. Virulence genes are frequently associated with bacterial pathogenicity in genus Legionella. In the present study, an assay was performed to detect ten virulence genes, including iraA, iraB, lvrA, lvrB, lvhD, cpxR, cpxA, dotA, icmC and icmD in different pathogenicity islands of 47 Legionella reference strains, 235 environmental strains isolated from water, and 4 clinical strains isolated from the lung tissue of pneumonia patients. The distribution frequencies of these genes in reference or/and environmental L. pneumophila strains were much higher than those in reference non-L. pneumophila or/and environmental non-L. pneumophila strains, respectively. L. pneumophila clinical strains also maintained higher frequencies of these genes compared to four other types of Legionella strains. Distribution frequencies of these genes in reference L. pneumophila strains were similar to those in environmental L. pneumophila strains. In contrast, environmental non-L. pneumophila maintained higher frequencies of these genes compared to those found in reference non-L. pneumophila strains. This study illustrates the association of virulence genes with Legionella pathogenicity and reveals the possible virulence evolution of non-L. pneumophia strains isolated from environmental water.

  1. Apt strain measurement technique for impulsive loading applications

    International Nuclear Information System (INIS)

    Nanda, Soumya Ranjan; Kulkarni, Vinayak; Sahoo, Niranjan

    2017-01-01

    The necessity of precise measurement of strain time history for impulsive loading applications has been addressed in the present investigation. Finite element modeling is initially carried out for a hemispherical test model and stress bar assembly to arrive at an appropriate location for strain measurement. In dynamic calibration experiments, strain measurements are performed using two wire and three wire quarter bride arrangements along with half bridge circuit. Usefulness of these arrangements has been verified by analyzing strain signals in time and frequency domains. Comparison of recovered force time histories proved that the half bridge circuit is the most suitable for such applications. Actual shock tube testing of the instrumented hemispherical test model confirmed the applicability of half bridge circuit for short duration strain measurements. (technical note)

  2. Fiber Strain Measurement for Wide Region Quasidistributed Sensing by Optical Correlation Sensor with Region Separation Techniques

    Directory of Open Access Journals (Sweden)

    Xunjian Xu

    2010-01-01

    Full Text Available The useful application of optical pulse correlation sensor for wide region quasidistributed fiber strain measurement is investigated. Using region separation techniques of wavelength multiplexing with FBGs and time multiplexing with intensity partial reflectors, the sensor measures the correlations between reference pulses and monitoring pulses from several cascadable selected sensing regions. This novel sensing system can select the regions and obtain the distributed strain information in any desired sensing region.

  3. In-situ measurement of texture and elastic strains with HIPPO-CRATES

    International Nuclear Information System (INIS)

    Hartig, Ch.; Vogel, S.C.; Mecking, H.

    2006-01-01

    In this paper, the micromechanical interaction between constituents of a metallic material during elastic and plastic deformation are analyzed by comparing experimental results with modeling predictions. This comparison aims at determining the locally acting internal stresses, the spatial distribution of strains and the rules allowing deriving the macroscopic behavior of the material from the behavior of its microscopic constituents. We report the application of a new deformation apparatus CRATES, which allows measuring texture and crystal lattice spacings, and from these crystal lattice strains, using neutron diffraction. From the in-situ measured elastic lattice strains ε hkl the corresponding local stresses can be derived. The deformation apparatus allows uni-axial tensile or compressive deformation up to 100 kN and is specifically designed for use in the HIPPO neutron time-of-flight diffractometer. In this paper, we report initial results on an iron-copper model system (Fe100, Fe33Cu67, Fe67Cu33, vol.%) and commercial magnesium alloys (Mg-AZ31 and Mg-AZ80). Finite element calculations using a crystal-plastic constitutive law, allowing for shear and hardening of crystallographic slip-systems, were used for the interpretation of the measurements

  4. Strain localization band width evolution by electronic speckle pattern interferometry strain rate measurement

    Energy Technology Data Exchange (ETDEWEB)

    Guelorget, Bruno [Institut Charles Delaunay-LASMIS, Universite de technologie de Troyes, FRE CNRS 2848, 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)], E-mail: bruno.guelorget@utt.fr; Francois, Manuel; Montay, Guillaume [Institut Charles Delaunay-LASMIS, Universite de technologie de Troyes, FRE CNRS 2848, 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)

    2009-04-15

    In this paper, electronic speckle pattern interferometry strain rate measurements are used to quantify the width of the strain localization band, which occurs when a sheet specimen is submitted to tension. It is shown that the width of this band decreases with increasing strain. Just before fracture, this measured width is about five times wider than the shear band and the initial sheet thickness.

  5. Simultaneous measurement of temperature and strain using a phase-shifted fiber Bragg grating inscribed by femtosecond laser

    Science.gov (United States)

    Jiang, Yajun; Liu, Chi; Li, Dong; Yang, Dexing; Zhao, Jianlin

    2018-04-01

    A novel method for simultaneous measurement of temperature and strain using a single phase-shifted fiber Bragg grating (PS-FBG) is proposed. The PS-FBG is produced by exposing the fusion-spliced fiber with a femtosecond laser and uniform phase mask. Due to the non-uniform structure and strain distribution in the fusion-spliced region, the phase-shift changes with different responses during increases to the temperature and strain; by measuring the central wavelengths and the loss difference of two transmission dips, temperature and strain can be determined simultaneously. The resolutions of this particular sensor in measuring temperature and strain are estimated to be  ±1.5 °C and  ±12.2 µɛ in a range from  -50 °C to 150 °C and from 0 µɛ to 2070 µɛ.

  6. Strain distribution analysis in Si/SiGe line structures for CMOS technology using Raman spectroscopy

    International Nuclear Information System (INIS)

    Hecker, M; Roelke, M; Hermann, P; Zschech, E; Vartanian, V

    2010-01-01

    Strained silicon underneath the field-effect transistor gate increases significantly the charge carrier mobility and thus improves the performance of leading-edge Complementary Metal Oxide Semiconductor (CMOS) devices. For better understanding of the structure-strain relationship on the nanoscale and for optimization of device structures, the measurement of the local strain state has become essential. Raman spectroscopy is used in the present investigation to analyze the strain distribution in and close to silicon/embedded silicon-germanium (SiGe) line structures in conjunction with strain modeling applying finite element analysis. Both experimental results and modeling indicate the impact of geometry on the stress state. An increase of compressive stress within the Si lines is obtained for increasing SiGe line widths and decreasing Si line widths. The stress state within the Si lines is shown to be a mixed one deviating from a pure uniaxial state. Underneath the SiGe cavities, the presence of a tensile stress was observed. To investigate a procedure to scale down the spatial resolution of the Raman measurements, tip-enhanced Raman scattering experiments have been performed on free-standing SiGe lines with 100nm line width and line distance. The results show superior resolution and strain information not attainable in conventional Raman scans.

  7. Strain gauge measurement uncertainties on hydraulic turbine runner blade

    International Nuclear Information System (INIS)

    Arpin-Pont, J; Gagnon, M; Tahan, S A; Coutu, A; Thibault, D

    2012-01-01

    Strains experimentally measured with strain gauges can differ from those evaluated using the Finite Element (FE) method. This difference is due mainly to the assumptions and uncertainties inherent to each method. To circumvent this difficulty, we developed a numerical method based on Monte Carlo simulations to evaluate measurement uncertainties produced by the behaviour of a unidirectional welded gauge, its position uncertainty and its integration effect. This numerical method uses the displacement fields of the studied part evaluated by an FE analysis. The paper presents a study case using in situ data measured on a hydraulic turbine runner. The FE analysis of the turbine runner blade was computed, and our numerical method used to evaluate uncertainties on strains measured at five locations with welded strain gauges. Then, measured strains and their uncertainty ranges are compared to the estimated strains. The uncertainty ranges obtained extended from 74 με to 165 με. Furthermore, the biases observed between the median of the uncertainty ranges and the FE strains varied from −36 to 36 με. Note that strain gauge measurement uncertainties depend mainly on displacement fields and gauge geometry.

  8. Measuring autogenous strain of concrete with corrugated moulds

    DEFF Research Database (Denmark)

    Tian, Qian; Jensen, Ole Mejlhede

    2008-01-01

    A reliable technique to quantify autogenous strain is a prerequisite to numerical modeling in stress calculations for high performance concrete. The introducing of a special kind of corrugated tube mould helps to transforming volume strain measurement into liner strain measurement in horizontal...... direction for fluid concrete, which not only realizes the continuous monitoring of the autogenous shrinkage since casting, but also effectively eliminates the disturbance resulting from gravity, temperature variation and mould restraint on measuring results. Based on this measuring technique, this paper...

  9. Performance of a distributed simultaneous strain and temperature sensor based on a Fabry-Perot laser diode and a dual-stage FBG optical demultiplexer.

    Science.gov (United States)

    Kim, Suhwan; Kwon, Hyungwoo; Yang, Injae; Lee, Seungho; Kim, Jeehyun; Kang, Shinwon

    2013-11-12

    A simultaneous strain and temperature measurement method using a Fabry-Perot laser diode (FP-LD) and a dual-stage fiber Bragg grating (FBG) optical demultiplexer was applied to a distributed sensor system based on Brillouin optical time domain reflectometry (BOTDR). By using a Kalman filter, we improved the performance of the FP-LD based OTDR, and decreased the noise using the dual-stage FBG optical demultiplexer. Applying the two developed components to the BOTDR system and using a temperature compensating algorithm, we successfully demonstrated the simultaneous measurement of strain and temperature distributions under various experimental conditions. The observed errors in the temperature and strain measured using the developed sensing system were 0.6 °C and 50 με, and the spatial resolution was 1 m, respectively.

  10. Standard guide for high-temperature static strain measurement

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1998-01-01

    1.1 This guide covers the selection and application of strain gages for the measurement of static strain up to and including the temperature range from 425 to 650°C (800 to 1200°F). This guide reflects some current state-of-the-art techniques in high temperature strain measurement, and will be expanded and updated as new technology develops. 1.2 This practice assumes that the user is familiar with the use of bonded strain gages and associated signal conditioning and instrumentation as discussed in Refs. (1) and (2). The strain measuring systems described are those that have proven effective in the temperature range of interest and were available at the time of issue of this practice. It is not the intent of this practice to limit the user to one of the gage types described nor is it the intent to specify the type of system to be used for a specific application. However, in using any strain measuring system including those described, the proposer must be able to demonstrate the capability of the proposed sy...

  11. Engineering strain measurements using the NPD at LANSCE

    International Nuclear Information System (INIS)

    Bourke, M.A.M.; Goldstone, J.A.; Lovell, K.J.

    1991-01-01

    The presence of residual stress in engineering components can affect their mechanical properties and structural integrity. Neutron diffraction is the only measuring technique which can provide spatially resolved non-destructive strain measurements in the interior of a component. By recording the change in the interplanar spacings elastic strains can be measured for individual lattice reflections. Also on a pulsed source, where all lattice reflections are recorded, profile refinement is an option which allows the strain to be obtained from changes in the lattice parameter. Measurements made at LANSCE demonstrate the potential for stress measurements on a pulsed source and indicate the advantages and disadvantages over measurements made on a reactor. (author)

  12. Performance of a Distributed Simultaneous Strain and Temperature Sensor Based on a Fabry-Perot Laser Diode and a Dual-Stage FBG Optical Demultiplexer

    Directory of Open Access Journals (Sweden)

    Shinwon Kang

    2013-11-01

    Full Text Available A simultaneous strain and temperature measurement method using a Fabry-Perot laser diode (FP-LD and a dual-stage fiber Bragg grating (FBG optical demultiplexer was applied to a distributed sensor system based on Brillouin optical time domain reflectometry (BOTDR. By using a Kalman filter, we improved the performance of the FP-LD based OTDR, and decreased the noise using the dual-stage FBG optical demultiplexer. Applying the two developed components to the BOTDR system and using a temperature compensating algorithm, we successfully demonstrated the simultaneous measurement of strain and temperature distributions under various experimental conditions. The observed errors in the temperature and strain measured using the developed sensing system were 0.6 °C and 50 με, and the spatial resolution was 1 m, respectively.

  13. Engineering strain measurements using the NPD at LANSCE

    International Nuclear Information System (INIS)

    Bourke, M.A.M.; Goldstone, J.A.; Lovell, K.J.

    1990-01-01

    The presence of residual stress in engineering components can affect their mechanical properties and structural integrity. Neutron diffraction is the only measuring technique which can provide spatially resolved non-destructive strain measurements in the interior of a component. By recording the change in the interplanar spacings elastic strains can be measured for individual lattice reflections. Also on a pulsed source, where all lattice reflections are recorded, profile refinement is an option which alloys the strain to be obtained from changes in the lattice parameter. Measurements made at LANSCE demonstrate the potential for stress measurements on a pulsed source and indicate the advantages and disadvantages over measurements made on a reactor. 5 refs., 5 figs

  14. Dark field electron holography for strain measurement

    Energy Technology Data Exchange (ETDEWEB)

    Beche, A., E-mail: armand.beche@fei.com [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Rouviere, J.L. [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Barnes, J.P.; Cooper, D. [CEA-LETI, Minatec Campus, F-38054 Grenoble (France)

    2011-02-15

    Dark field electron holography is a new TEM-based technique for measuring strain with nanometer scale resolution. Here we present the procedure to align a transmission electron microscope and obtain dark field holograms as well as the theoretical background necessary to reconstruct strain maps from holograms. A series of experimental parameters such as biprism voltage, sample thickness, exposure time, tilt angle and choice of diffracted beam are then investigated on a silicon-germanium layer epitaxially embedded in a silicon matrix in order to obtain optimal dark field holograms over a large field of view with good spatial resolution and strain sensitivity. -- Research Highlights: {yields} Step by step explanation of the dark field electron holography technique. {yields} Presentation of the theoretical equations to obtain quantitative strain map. {yields} Description of experimental parameters influencing dark field holography results. {yields} Quantitative strain measurement on a SiGe layer embedded in a silicon matrix.

  15. Influence of Cement Particle-Size Distribution on Early Age Autogenous Strains and Stresses in Cement-Based Materials

    DEFF Research Database (Denmark)

    Bentz, Dale P.; Jensen, Ole Mejlhede; Hansen, Kurt Kielsgaard

    2001-01-01

    The influence of cement particle-size distribution on autogenous strains and stresses in cement pastes of identical water-to-cement ratios is examined for cement powders of four different finenesses. Experimental measurements include chemical shrinkage, to quantify degree of hydration; internal r...

  16. Measurement of the residual stress distribution in a thick pre-stretched aluminum plate

    Science.gov (United States)

    Yuan, S. X.; Li, X. Q.; M, S.; Zhang, Y. C.; Gong, Y. D.

    2008-12-01

    Thick pre-stretched aluminum alloy plates are widely used in aircraft, while machining distortion caused by initial residual stress release in thick plates is a common and serious problem. To reduce the distortion, the residual stress distribution in thick plate must be measured. According to the characteristics of the thick pre-stretched aluminum alloy plate, based the elastic mechanical theory, this article deduces the modified layer-removal strain method adapting two different strain situations, which are caused by tensile and compressive stress. To validate this method, the residual stresses distribution along the thick direction of plate 2D70T351 is measured by this method, it is shown that the new method deduced in this paper is simple and accurate, and is very useful in engineering.

  17. Development of nondestructive hybrid measuring method for three-dimensional residual stress distribution of thick welded joint. Hybrid measuring method of inherent strain method and neutron diffraction method

    International Nuclear Information System (INIS)

    Nakacho, Keiji; Kasahara, Norifumi; Tamura, Ryota

    2012-01-01

    The measuring methods of the residual stress are classified into destructive one and nondestructive one. The inherent strain method (ISM) is destructive one. The neutron diffraction method (NDM) is nondestructive one. But the measurable depth is limited within about 20 mm and the method cannot measure the weld zone, without destruction of the object. So, in this study, the hybrid measuring method has been developed, by combining the ISM and the NDM. The theory of the hybrid method is the same as the ISM. In the analysis, the strains measured by the NDM without destruction are used. This hybrid measuring method is a true nondestructive measuring method for a thick welded joint. The applicability of the hybrid method has been verified by simulation, using a butt welded joint of thick pipes. In the simulation, the reliable order of the strains measured by the present NDM is very important, and was considered as 10 micro. The measurable regions by the present NDM were assumed. Under the above conditions, the data (the residual elastic strains assumed to be measured by the NDM) were made, and used in the ISM. As a result of such simulation, it has been cleared that the estimated residual stress has very high accuracy, if enough data are used. The required number of data is less than the ISM. (author)

  18. Longitudinally Jointed Edge-wise Compression Honeycomb Composite Sandwich Coupon Testing and FE Analysis: Three Methods of Strain Measurement, and Comparison

    Science.gov (United States)

    Farrokh, Babak; AbdulRahim, Nur Aida; Segal, Ken; Fan, Terry; Jones, Justin; Hodges, Ken; Mashni, Noah; Garg, Naman; Sang, Alex; Gifford, Dawn; hide

    2013-01-01

    Three means (i.e., typical foil strain gages, fiber optic sensors, and a digital image correlation (DIC) system) were implemented to measure strains on the back and front surfaces of a longitudinally jointed curved test article subjected to edge-wise compression testing, at NASA Goddard Space Flight Center, according to ASTM C364. The Pre-test finite element analysis (FEA) was conducted to assess ultimate failure load and predict strain distribution pattern throughout the test coupon. The predicted strain pattern contours were then utilized as guidelines for installing the strain measurement instrumentations. The strain gages and fiber optic sensors were bonded on the specimen at locations with nearly the same strain values, as close as possible to each other, so that, comparisons between the measured strains by strain gages and fiber optic sensors, as well as the DIC system are justified. The test article was loaded to failure (at approximately 38 kips), at the strain value of approximately 10,000mu epsilon As a part of this study, the validity of the measured strains by fiber optic sensors is examined against the strain gage and DIC data, and also will be compared with FEA predictions.

  19. Strain rate measurement by Electronic Speckle Pattern Interferometry: A new look at the strain localization onset

    International Nuclear Information System (INIS)

    Guelorget, Bruno; Francois, Manuel; Vial-Edwards, Cristian; Montay, Guillaume; Daniel, Laurent; Lu, Jian

    2006-01-01

    In-plane Electronic Speckle Pattern Interferometry has been successfully used during tensile testing of semi-hard copper sheets in order to measure the strain rate. On one hand, heterogeneity in strain rate field has been found before the maximum of the tensile force (ε t ≅ 19.4 and 25.4%, respectively). Thus, a localization phenomenon occurs before the classic Considere's criterion (dF = 0) for the diffuse neck initiation. On the other hand, strain rate measurement before fracture shows the moment where one of the two slip band systems becomes predominant, then strain concentrates in a small area, the shear band. Uncertainty evaluation has been carried out, which shows a very good accuracy of the total strain and the strain rate measurements

  20. Strain rate measurement by Electronic Speckle Pattern Interferometry: A new look at the strain localization onset

    Energy Technology Data Exchange (ETDEWEB)

    Guelorget, Bruno [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)]. E-mail: bruno.guelorget@utt.fr; Francois, Manuel [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Vial-Edwards, Cristian [Departemento de Ingenieria Mecanica y Metalurgica, Pontificia Universidad Catolica de Chile, Vicuna Mackenna 4860, 6904411 Santiago (Chile); Montay, Guillaume [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Daniel, Laurent [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Lu, Jian [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)

    2006-01-15

    In-plane Electronic Speckle Pattern Interferometry has been successfully used during tensile testing of semi-hard copper sheets in order to measure the strain rate. On one hand, heterogeneity in strain rate field has been found before the maximum of the tensile force ({epsilon} {sup t} {approx_equal} 19.4 and 25.4%, respectively). Thus, a localization phenomenon occurs before the classic Considere's criterion (dF = 0) for the diffuse neck initiation. On the other hand, strain rate measurement before fracture shows the moment where one of the two slip band systems becomes predominant, then strain concentrates in a small area, the shear band. Uncertainty evaluation has been carried out, which shows a very good accuracy of the total strain and the strain rate measurements.

  1. Effects of different numbers of mini-dental implants on alveolar ridge strain distribution under mandibular implant-retained overdentures.

    Science.gov (United States)

    Warin, Pongsakorn; Rungsiyakull, Pimduen; Rungsiyakull, Chaiy; Khongkhunthian, Pathawee

    2018-01-01

    To investigate the strains around mini-dental implants (MDIs) and retromolar edentulous areas when using different numbers of MDIs in order to retain mandibular overdentures. Four different prosthetic situations were fabricated on an edentulous mandibular model including a complete denture (CD), and three overdentures, retained by four, three or two MDIs in the interforaminal region with retentive attachments. A static load of 200N was applied on the posterior teeth of the dentures under bilateral or unilateral loading conditions. The strains at the mesial and distal of the MDIs and the retromolar edentulous ridges were measured using twelve strain gauges. Comparisons of the mean microstrains among all strain gauges in all situations were analyzed. The strain distribution determined during bilateral loading experienced a symmetrical distribution; while during unilateral loading, the recorded strains tended to change from compressive strains on the loaded side to tensile strains. Overall, the number of MDIs was found to be passively correlated to the generated compressive strain. The highest strains were recorded in the four MDIs followed by three, two MDIs retained overdenture and CD situations, respectively. The highest strain was found around the terminal MDI. The use of a low number of MDIs tends to produce low strain values in the retromolar denture-bearing area and around the terminal MDIs during posterior loadings. However, when using a high number of MDIs, the overdenture tends to have more stability during function. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  2. Development of a contact probe incorporating a Bragg grating strain sensor for nano coordinate measuring machines

    International Nuclear Information System (INIS)

    Ji, H; Hsu, H-Y; Kong, L X; Wedding, A B

    2009-01-01

    This paper presents a novel optical fibre based micro contact probe system with high sensitivity and repeatability. In this optical fibre probe with a fused spherical tip, a fibre Bragg grating has been utilized as a strain sensor in the probe stem. When the probe tip contacts the surface of the part, a strain will be induced along the probe stem and will produce a Bragg wavelength shift. The contact signal can be issued once the wavelength shift signal is produced and demodulated. With the fibre grating sensor element integrated into the probe directly, the probe system shows a high sensitivity. In this work, the strain distributions along the probe stem with the probe under axial and lateral load are analysed. A simulation of the strain distribution was performed using the finite element package ANSYS 11. Performance tests using a piezoelectric transducer stage with a displacement resolution of 1.5 nm yielded a measurement resolution of 60 nm under axial loading

  3. Strain distribution in single, suspended germanium nanowires studied using nanofocused x-rays

    DEFF Research Database (Denmark)

    Keplinger, Mario; Grifone, Raphael; Greil, Johannes

    2016-01-01

    Within the quest for direct band-gap group IV materials, strain engineering in germanium is one promising route. We present a study of the strain distribution in single, suspended germanium nanowires using nanofocused synchrotron radiation. Evaluating the probed Bragg reflection for different ill...

  4. A piezoelectric transducer for measurement of dynamic strain in pipes

    Energy Technology Data Exchange (ETDEWEB)

    Lannes, Daniel P.; Gama, Antonio L. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Dept. de Engenharia Mecanica

    2009-07-01

    This work presents a new strain transducer developed mainly for the inspection and evaluation of piping systems with excessive vibration. Vibration is one of the most common causes of piping failures. These failures could be avoided if the vibration problems were identified and quickly evaluated. Procedures for evaluation of piping vibration are usually based on pipe velocity or displacement. Although simple and fast, these procedures do not provide precise information on the risk of piping fatigue failure. Through the measurement of pipe dynamic strains the risk of failure due to vibration can be determined more accurately. The measurement of strain is usually performed using the conventional strain gauge method. Although efficient and accurate, the implementation of the conventional strain gauge technique may become a difficult task in certain industrial scenarios. Motivated by the need of a simple and rapid method for pipe dynamic strain measurement, a piezoelectric dynamic strain transducer was developed. This work presents a description of the piezoelectric strain transducer and the preliminary results of pipe strain measurements. The transducer can be applied directly to the pipe through magnetic bases allowing for the quick measurement of the dynamic strains in many points of the pipe. The transducer signal can be read with the same commercial data collectors used for accelerometers. (author)

  5. Internal Stress Distribution Measurement of TIG Welded SUS304 Samples Using Neutron Diffraction Technique

    Science.gov (United States)

    Muslih, M. Refai; Sumirat, I.; Sairun; Purwanta

    2008-03-01

    The distribution of residual stress of SUS304 samples that were undergone TIG welding process with four different electric currents has been measured. The welding has been done in the middle part of the samples that was previously grooved by milling machine. Before they were welded the samples were annealed at 650 degree Celsius for one hour. The annealing process was done to eliminate residual stress generated by grooving process so that the residual stress within the samples was merely produced from welding process. The calculation of distribution of residual stress was carried out by measuring the strains within crystal planes of Fe(220) SUS304. Strain, Young modulus, and Poisson ratio of Fe(220) SUS304 were measured using DN1-M neutron diffractometer. Young modulus and Poisson ratio of Fe(220) SUS304 sample were measured in-situ. The result of calculations showed that distribution of residual stress of SUS304 in the vicinity of welded area is influenced both by treatments given at the samples-making process and by the electric current used during welding process.

  6. Strain measurement in concrete using embedded carbon roving-based sensors

    International Nuclear Information System (INIS)

    Quadflieg, Till; Gries, Thomas; Stolyarov, Oleg

    2016-01-01

    This paper presents the results of the application of carbon rovings as strain sensors for measuring the strain in concrete. In this work, three types of electrically conductive carbon roving with different characteristics were used. The possibility of using carbon rovings as a strain sensor is demonstrated via measurements in tensile and four point bending tests. The experimental setups and methods for measuring the electrical resistance of carbon roving in the roving and concrete are described. The results of the characterization of the electrical behavior as a function of strain of carbon rovings and concrete are presented and discussed. The obtained results indicate that the strain range of carbon rovings optimally corresponds to the strain range of concrete. This characteristic behavior makes the carbon rovings well suited for the use as strain sensors. A good correlation has been found between the electrical resistance-strain curve of the carbon roving and the measurements in the concrete.

  7. Modelling non-uniform strain distributions in aerospace composites using fibre Bragg gratings

    NARCIS (Netherlands)

    Rajabzadehdizaji, Aydin; Groves, R.M.; Hendriks, R.C.; Heusdens, R.; Chung, Y.; Jin, W.; Lee, B.; Canning, J.; Nakamura, K.; Yuan, L.

    2017-01-01

    In this paper the behaviour of fibre Bragg grating (FBG) sensors under non-uniform strain distributions was analysed. Using the fundamental matrix approach, the length of the FBG sensor was discretised, with each segment undergoing different strain values. FBG sensors that are embedded inside

  8. X-ray microbeam measurements of individual dislocation cell elastic strains in deformed single-crystal copper

    Energy Technology Data Exchange (ETDEWEB)

    Levine, Lyle E. [National Institute of Standards and Technology (NIST); Larson, Ben C [ORNL; Yang, Wenge [Carnegie Institution of Washington; Kassner, Michael E. [University of Southern California; Tischler, Jonathan Zachary [ORNL; Delos-Reyes, Michael A. [University of Southern California; Fields, Richard J. [National Institute of Standards and Technology (NIST); Liu, Wenjun [Argonne National Laboratory (ANL)

    2006-01-01

    The distribution of elastic strains (and thus stresses) at the sub-micrometer length scale within deformed metal single crystals has surprisingly broad implications for our understanding of important physical phenomena. These include the evolution of the complex dislocation structures that govern mechanical behavior within individual grains [1-4], the transport of dislocations through such structures [5-7], changes in mechanical properties that occur during reverse loading [8-10] (e.g. sheet metal forming), and the analyses of diffraction line profiles for microstructural studies of these phenomena [11-17]. We present the first direct, spatially-resolved measurements of the elastic strains within individual dislocation cells in copper single crystals deformed in tension and compression along <100> axes. Broad distributions of elastic strains are found, with profound implications for theories of dislocation structure evolution [4,18], dislocation transport [5-7], and the extraction of dislocation parameters from X-ray line profiles [11-17,19].

  9. Measurement of minute local strain in semiconductor materials and electronic devices by using a highly parallel X-ray microbeam

    International Nuclear Information System (INIS)

    Matsui, J.; Tsusaka, Y.; Yokoyama, K.; Takeda, S.; Katou, M.; Kurihara, H.; Watanabe, K.; Kagoshima, Y.; Kimura, S.

    2003-01-01

    We have developed an X-ray microbeam with a small angular divergence by adopting X-ray optics with successive use of asymmetric Bragg reflection from silicon crystals for the both polarizations of the synchrotron X-rays. The microbeam actually obtained is several microns in size and possesses an angular divergence of less than 2 arcsec which enables us to measure the strain of 10 -5 -10 -6 . By scanning the sample against the microbeam, distribution of the minute local strain in various regions of semiconductor crystals for electronic devices, e.g., the strain around the SiO 2 /Si film edge in silicon devices, the strain in an InGaAsP/InP stripe laser were measured

  10. Deformation Measurement of a Driven Pile Using Distributed Fibre-optic Sensing

    Science.gov (United States)

    Monsberger, Christoph; Woschitz, Helmut; Hayden, Martin

    2016-03-01

    New developments in distributed fibre-optic sensing allow the measurement of strain with a very high precision of about 1 µm / m and a spatial resolution of 10 millimetres or even better. Thus, novel applications in several scientific fields may be realised, e. g. in structural monitoring or soil and rock mechanics. Especially due to the embedding capability of fibre-optic sensors, fibre-optic systems provide a valuable extension to classical geodetic measurement methods, which are limited to the surface in most cases. In this paper, we report about the application of an optical backscatter reflectometer for deformation measurements along a driven pile. In general, pile systems are used in civil engineering as an efficient and economic foundation of buildings and other structures. Especially the length of the piles is crucial for the final loading capacity. For optimization purposes, the interaction between the driven pile and the subsurface material is investigated using pile testing methods. In a field trial, we used a distributed fibre-optic sensing system for measuring the strain below the surface of an excavation pit in order to derive completely new information. Prior to the field trial, the fibre-optic sensor was investigated in the laboratory. In addition to the results of these lab studies, we briefly describe the critical process of field installation and show the most significant results from the field trial, where the pile was artificially loaded up to 800 kN. As far as we know, this is the first time that the strain is monitored along a driven pile with such a high spatial resolution.

  11. Measurement of Strain and Strain Rate during the Impact of Tennis Ball Cores

    Directory of Open Access Journals (Sweden)

    Ben Lane

    2018-03-01

    Full Text Available The aim of this investigation was to establish the strains and strain rates experienced by tennis ball cores during impact to inform material characterisation testing and finite element modelling. Three-dimensional surface strains and strain rates were measured using two high-speed video cameras and corresponding digital image correlation software (GOM Correlate Professional. The results suggest that material characterisation testing to a maximum strain of 0.4 and a maximum rate of 500 s−1 in tension and to a maximum strain of −0.4 and a maximum rate of −800 s−1 in compression would encapsulate the demands placed on the material during impact and, in turn, define the range of properties required to encapsulate the behavior of the material during impact, enabling testing to be application-specific and strain-rate-dependent properties to be established and incorporated in finite element models.

  12. Effect of Local Strain Distribution of Cold-Rolled Alloy 690 on Primary Water Stress Corrosion Crack Growth Behavior

    Directory of Open Access Journals (Sweden)

    Kim S.-W.

    2017-06-01

    Full Text Available This work aims to study the stress corrosion crack growth behavior of cold-rolled Alloy 690 in the primary water of a pressurized water reactor. Compared with Alloy 600, which shows typical intergranular cracking along high angle grain boundaries, the cold-rolled Alloy 690, with its heterogeneous microstructure, revealed an abnormal crack growth behavior in mixed mode, that is, in transgranular cracking near a banded region, and in intergranular cracking in a matrix region. From local strain distribution analysis based on local mis-orientation, measured along the crack path using the electron back scattered diffraction method, it was suggested that the abnormal behavior was attributable to a heterogeneity of local strain distribution. In the cold-rolled Alloy 690, the stress corrosion crack grew through a highly strained area formed by a prior cold-rolling process in a direction perpendicular to the maximum principal stress applied during a subsequent stress corrosion cracking test.

  13. Design and performance investigation of a highly accurate apodized fiber Bragg grating-based strain sensor in single and quasi-distributed systems.

    Science.gov (United States)

    Ali, Taha A; Shehata, Mohamed I; Mohamed, Nazmi A

    2015-06-01

    In this work, fiber Bragg grating (FBG) strain sensors in single and quasi-distributed systems are investigated, seeking high-accuracy measurement. Since FBG-based strain sensors of small lengths are preferred in medical applications, and that causes the full width at half-maximum (FWHM) to be larger, a new apodization profile is introduced for the first time, to the best of our knowledge, with a remarkable FWHM at small sensor lengths compared to the Gaussian and Nuttall profiles, in addition to a higher mainlobe slope at these lengths. A careful selection of apodization profiles with detailed investigation is performed-using sidelobe analysis and the FWHM, which are primary judgment factors especially in a quasi-distributed configuration. A comparison between the elite selection of apodization profiles (extracted from related literature) and the proposed new profile is carried out covering the reflectivity peak, FWHM, and sidelobe analysis. The optimization process concludes that the proposed new profile with a chosen small length (L) of 10 mm and Δnac of 1.4×10-4 is the optimum choice for single stage and quasi-distributed strain-sensor networks, even better than the Gaussian profile at small sensor lengths. The proposed profile achieves the smallest FWHM of 15 GHz (suitable for UDWDM), and the highest mainlobe slope of 130 dB/nm. For the quasi-distributed scenario, a noteworthy high isolation of 6.953 dB is achieved while applying a high strain value of 1500 μstrain (με) for a five-stage strain-sensing network. Further investigation was undertaken, proving that consistency in choosing the apodization profile in the quasi-distributed network is mandatory. A test was made of the inclusion of a uniform apodized sensor among other apodized sensors with the proposed profile in an FBG strain-sensor network.

  14. Influence of Palatal Coverage and Implant Distribution on Denture Strain in Maxillary Implant Overdentures.

    Science.gov (United States)

    Takahashi, Toshihito; Gonda, Tomoya; Tomita, Akiko; Mizuno, Yoko; Maeda, Yoshinobu

    2016-01-01

    As maxillary implant overdentures are being increasingly used in clinical practice, prosthodontic complications related to these dentures are also reported more often. The purpose of this study was to examine the influence of palatal coverage and implant distribution on the shear strain of maxillary implant overdentures. A maxillary edentulous model with implants inserted in the anterior, premolar, and molar areas was fabricated. Two kinds of experimental overdentures, with and without palatal coverage, were also fabricated, and two strain gauges were attached at the midline of the labial and palatal sides. A vertical occlusal load of 98 N was applied through a mandibular complete denture, and the shear strain in each denture was compared by analysis of variance (P = .05). In all situations, the shear strain in palateless dentures was significantly higher than in dentures with palate on both sides (P overdentures exhibited much higher strain than overdentures with palate regardless of the implant distribution; this may cause more prosthodontic and implant complications. The most favorable configuration to prevent complications in maxillary implant overdentures was palatal coverage that was supported by more than four widely distributed implants.

  15. Simultaneous distributed strain and temperature sensing based on combined Raman–Brillouin scattering using Fabry–Perot lasers

    International Nuclear Information System (INIS)

    Bolognini, Gabriele; Soto, Marcelo A; Di Pasquale, Fabrizio

    2010-01-01

    An investigation is performed of the possibility of achieving simultaneous distributed strain and temperature sensing based on hybrid Raman–Brillouin scattering with the use of multi-wavelength optical sources such as common Fabry–Perot (FP) lasers. By employing a self-heterodyne detection scheme based on a multi-wavelength optical local oscillator, the benefits of FP lasers are fully exploited, allowing for high-power Raman intensity measurements and a simultaneous high-accuracy detection of the Brillouin frequency shift parameter for each FP longitudinal mode. Experimental results point out a significant reduction of coherent Rayleigh noise, and highlight the enhanced performance in hybrid Raman–Brillouin sensing when using FP lasers; in particular using standard FP lasers at 1550 nm results in about 12 dB (7 dB) temperature (strain) accuracy improvement at 25 km sensing distance with respect to the use of standard distributed feedback lasers

  16. Development and Measurement of Strain Free RF Photoinjector Vacuum Windows

    CERN Document Server

    Biedron, Sandra G

    2004-01-01

    RF photoinjectors produce the highest brightness electron bunches only under nearly ideal illumination by a drive laser. The vacuum window used to introduce the laser beam is an essential element that may potentially degrade any distribution, making it difficult or impossible to know the actual uniformity achieved at the cathode. Because of the necessity to obtain ultrahigh vacuum near the photoinjector, some restrictions are imposed on the fabrication technology available to manufacture distortion-free windows. At the UV wavelengths commonly used for photoinjectors, it is challenging to measure and eliminate degradation caused by vacuum windows. Here, we discuss the initial laser-based measurements of a strain-free, coated, UHV window manufactured by Insulator Seal in collaboration with members of Brookhaven and Argonne National Laboratories.

  17. Dynamic strain measurements in a sliding microstructured contact

    International Nuclear Information System (INIS)

    Bennewitz, Roland; David, Jonathan; Lannoy, Charles-Francois de; Drevniok, Benedict; Hubbard-Davis, Paris; Miura, Takashi; Trichtchenko, Olga

    2008-01-01

    A novel experiment is described which measures the tangential strain development across the contact between a PDMS (polydimethylsiloxane) block and a glass surface during the initial stages of sliding. The surface of the PDMS block has been microfabricated to take the form of a regular array of pyramidal tips at 20 μm separation. Tangential strain is measured by means of light scattering from the interface between the block and surface. Three phases are observed in all experiments: initial shear deformation of the whole PDMS block, a pre-sliding tangential compression of the tip array with stepwise increase of the compressive strain, and sliding in stick-slip movements as revealed by periodic variation of the strain. The stick-slip sliding between the regular tip array and the randomly rough counter surface always takes on the periodicity of the tip array. The fast slip can cause either a sudden increase or a sudden decrease in compressive strain

  18. Measurement of minute local strain in semiconductor materials and electronic devices by using a highly parallel X-ray microbeam

    CERN Document Server

    Matsui, J; Yokoyama, K; Takeda, S; Katou, M; Kurihara, H; Watanabe, K; Kagoshima, Y; Kimura, S

    2003-01-01

    We have developed an X-ray microbeam with a small angular divergence by adopting X-ray optics with successive use of asymmetric Bragg reflection from silicon crystals for the both polarizations of the synchrotron X-rays. The microbeam actually obtained is several microns in size and possesses an angular divergence of less than 2 arcsec which enables us to measure the strain of 10 sup - sup 5 -10 sup - sup 6. By scanning the sample against the microbeam, distribution of the minute local strain in various regions of semiconductor crystals for electronic devices, e.g., the strain around the SiO sub 2 /Si film edge in silicon devices, the strain in an InGaAsP/InP stripe laser were measured.

  19. Measurement of minute local strain in semiconductor materials and electronic devices by using a highly parallel X-ray microbeam

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, J. E-mail: matsui@sci.himeji-tech.ac.jp; Tsusaka, Y.; Yokoyama, K.; Takeda, S.; Katou, M.; Kurihara, H.; Watanabe, K.; Kagoshima, Y.; Kimura, S

    2003-01-01

    We have developed an X-ray microbeam with a small angular divergence by adopting X-ray optics with successive use of asymmetric Bragg reflection from silicon crystals for the both polarizations of the synchrotron X-rays. The microbeam actually obtained is several microns in size and possesses an angular divergence of less than 2 arcsec which enables us to measure the strain of 10{sup -5}-10{sup -6}. By scanning the sample against the microbeam, distribution of the minute local strain in various regions of semiconductor crystals for electronic devices, e.g., the strain around the SiO{sub 2}/Si film edge in silicon devices, the strain in an InGaAsP/InP stripe laser were measured.

  20. Measured Strain of Nb3Sn Coils During Excitation and Quench

    International Nuclear Information System (INIS)

    Caspi, S.; Bartlett, S.E.; Dietderich, D.R.; Ferracin, P.; Gourlay, S.A.; Hannaford, C.R.; Hafalia, A.R.; Lietzke, S.; Mattafirri, M.; Nyman, M.; Sabbi, G.

    2005-01-01

    The strain in a high field Nb 3 Sn coil was measured during magnet assembly, cool-down, excitation and spot heater quenches. Strain was measured with a full bridge strain gauge mounted directly over the turns and impregnated with the coil. Two such coils were placed in a ''common coil'' fashion capable of reaching 11T at 4.2K. The measured steady state strain in the coil is compared with results obtained using the FEM code ANSYS. During quenches, the transient strain (due to temperature rise) was also measured and compared with the calculated mechanical time response to a quench

  1. Resonant tunneling measurements of size-induced strain relaxation

    Science.gov (United States)

    Akyuz, Can Deniz

    Lattice mismatch strain available in such semiconductor heterostructures as Si/SiGe or GaAs/AlGaAs can be employed to alter the electronic and optoelectronic properties of semiconductor structures and devices. When deep submicron structures are fabricated from strained material, strained layers relax by sidewall expansion giving rise to size- and geometry-dependent strain gradients throughout the structure. This thesis describes a novel experimental technique to probe the size-induced strain relaxation by studying the tunneling current characteristics of strained p-type Si/SiGe resonant tunneling diodes. Our current-voltage measurements on submicron strained p-Si/SiGe double- and triple-barrier resonant tunneling structures as a function of device diameter, D, provide experimental access to both the average strain relaxation (which leads to relative shifts in the tunneling current peak positions) and strain gradients (which give rise to a fine structure in the current peaks due to inhomogeneous strain-induced lateral quantization). We find that strain relaxation is significant, with a large fraction of the strain energy relaxed on average in D ≤ 0.25 m m devices. Further, the in-plane potentials that arise from inhomogeneous strain gradients are large. In the D ˜ 0.2 m m devices, the corresponding lateral potentials are approximately parabolic exceeding ˜ 25 meV near the perimeter. These potentials create discrete hole states in double-barrier structures (single well), and coupled hole states in triple-barrier structures (two wells). Our results are in excellent agreement with finite-element strain calculations in which the strained layers are permitted to relax to a state of minimum energy by sidewall expansion. Size-induced strain relaxation will undoubtedly become a serious technological issue once strained devices are scaled down to the deep submicron regime. Interestingly, our calculations predict and our measurements are consistent with the appearance of

  2. Lattice strain measurements on sandstones under load using neutron diffraction

    Science.gov (United States)

    Frischbutter, A.; Neov, D.; Scheffzük, Ch.; Vrána, M.; Walther, K.

    2000-11-01

    Neutron diffraction methods (both time-of-flight- and angle-dispersive diffraction) are applied to intracrystalline strain measurements on geological samples undergoing uniaxial increasing compressional load. The experiments were carried out on Cretaceous sandstones from the Elbezone (East Germany), consisting of >95% quartz which are bedded but without crystallographic preferred orientation of quartz. From the stress-strain relation the Young's modulus for our quartz sample was determined to be (72.2±2.9) GPa using results of the neutron time-of-flight method. The influence of different kinds of bedding in sandstones (laminated and convolute bedding) could be determined. We observed differences of factor 2 (convolute bedding) and 3 (laminated bedding) for the elastic stiffness, determined with angle dispersive neutron diffraction (crystallographic strain) and with strain gauges (mechanical strain). The data indicate which geological conditions may influence the stress-strain behaviour of geological materials. The influence of bedding on the stress-strain behaviour of a laminated bedded sandstone was indicated by direct residual stress measurements using neutron time-of-flight diffraction. The measurements were carried out six days after unloading the sample. Residual strain was measured for three positions from the centre to the periphery and within two radial directions of the cylinder. We observed that residual strain changes from extension to compression in a different manner for two perpendicular directions of the bedding plane.

  3. Visual Measurement of Suture Strain for Robotic Surgery

    Directory of Open Access Journals (Sweden)

    John Martell

    2011-01-01

    Full Text Available Minimally invasive surgical procedures offer advantages of smaller incisions, decreased hospital length of stay, and rapid postoperative recovery to the patient. Surgical robots improve access and visualization intraoperatively and have expanded the indications for minimally invasive procedures. A limitation of the DaVinci surgical robot is a lack of sensory feedback to the operative surgeon. Experienced robotic surgeons use visual interpretation of tissue and suture deformation as a surrogate for tactile feedback. A difficulty encountered during robotic surgery is maintaining adequate suture tension while tying knots or following a running anastomotic suture. Displaying suture strain in real time has potential to decrease the learning curve and improve the performance and safety of robotic surgical procedures. Conventional strain measurement methods involve installation of complex sensors on the robotic instruments. This paper presents a noninvasive video processing-based method to determine strain in surgical sutures. The method accurately calculates strain in suture by processing video from the existing surgical camera, making implementation uncomplicated. The video analysis method was developed and validated using video of suture strain standards on a servohydraulic testing system. The video-based suture strain algorithm is shown capable of measuring suture strains of 0.2% with subpixel resolution and proven reliability under various conditions.

  4. Design and implementation of an x-ray strain measurement capability using a rotating anode machine

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, J.A.; Rangaswamy, P.; Lujan, M. Jr.; Bourke, M.A.M.

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Residual stresses close to the surface can improve the reliability and lifetime of parts for technological applications. X-ray diffraction plays a significant role in gaining an exact knowledge of the stresses at the surface and their depth distribution. An x-ray capability at Los Alamos is key to developing and maintaining industrial collaborations in strain effects. To achieve this goal, the authors implemented a residual strain measuring station on the rotating anode x-ray instrument at the Lujan Center. This capability has been used to investigate residual strains in heat treated automotive components, machining effects on titanium alloys, resistance welded steel joints, titanium matrix fiber reinforced composites, ceramic matrix composites, thin films, and ceramic coatings. The overall objective is to combine both x-ray and neutron diffraction measurements with numerical models (e.g., finite element calculations).

  5. Utilizing Photogrammetry and Strain Gage Measurement to Characterize Pressurization of an Inflatable Module

    Science.gov (United States)

    Valle, Gerard D.; Selig, Molly; Litteken, Doug; Oliveras, Ovidio

    2012-01-01

    This paper documents the integration of a large hatch penetration into an inflatable module. This paper also documents the comparison of analytical load predictions with measured results utilizing strain measurement. Strain was measured by utilizing photogrammetric measurement and through measurement obtained from strain gages mounted to selected clevises that interface with the structural webbings. Bench testing showed good correlation between strain measurement obtained from an extensometer and photogrammetric measurement especially after the fabric has transitioned through the low load/high strain region of the curve. Test results for the full-scale torus showed mixed results in the lower load and thus lower strain regions. Overall strain, and thus load, measured by strain gages and photogrammetry tracked fairly well with analytical predictions. Methods and areas of improvements are discussed.

  6. Utilizing Photogrammetry and Strain Gage Measurement to Characterize Pressurization of Inflatable Modules

    Science.gov (United States)

    Mohammed, Anil

    2011-01-01

    This paper focuses on integrating a large hatch penetration into inflatable modules of various constructions. This paper also compares load predictions with test measurements. The strain was measured by utilizing photogrammetric methods and strain gages mounted to select clevises that interface with the structural webbings. Bench testing showed good correlation between strain data collected from an extensometer and photogrammetric measurements, even when the material transitioned from the low load to high load strain region of the curve. The full-scale torus design module showed mixed results as well in the lower load and high strain regions. After thorough analysis of photogrammetric measurements, strain gage measurements, and predicted load, the photogrammetric measurements seem to be off by a factor of two.

  7. Internal displacement and strain measurement using digital volume correlation: a least-squares framework

    International Nuclear Information System (INIS)

    Pan, Bing; Wu, Dafang; Wang, Zhaoyang

    2012-01-01

    As a novel tool for quantitative 3D internal deformation measurement throughout the interior of a material or tissue, digital volume correlation (DVC) has increasingly gained attention and application in the fields of experimental mechanics, material research and biomedical engineering. However, the practical implementation of DVC involves important challenges such as implementation complexity, calculation accuracy and computational efficiency. In this paper, a least-squares framework is presented for 3D internal displacement and strain field measurement using DVC. The proposed DVC combines a practical linear-intensity-change model with an easy-to-implement iterative least-squares (ILS) algorithm to retrieve 3D internal displacement vector field with sub-voxel accuracy. Because the linear-intensity-change model is capable of accounting for both the possible intensity changes and the relative geometric transform of the target subvolume, the presented DVC thus provides the highest sub-voxel registration accuracy and widest applicability. Furthermore, as the ILS algorithm uses only first-order spatial derivatives of the deformed volumetric image, the developed DVC thus significantly reduces computational complexity. To further extract 3D strain distributions from the 3D discrete displacement vectors obtained by the ILS algorithm, the presented DVC employs a pointwise least-squares algorithm to estimate the strain components for each measurement point. Computer-simulated volume images with controlled displacements are employed to investigate the performance of the proposed DVC method in terms of mean bias error and standard deviation error. Results reveal that the present technique is capable of providing accurate measurements in an easy-to-implement manner, and can be applied to practical 3D internal displacement and strain calculation. (paper)

  8. Residual strains in girth-welded linepipe

    International Nuclear Information System (INIS)

    MacEwen, S.R.; Holden, T.M.; Powell, B.M.; Lazor, R.B.

    1987-07-01

    High resolution neutron diffraction has been used to measure the axial residual strains in and adjacent to a multipass girth weld in a complete section of 914 mm (36 inches) diameter, 16 mm (5/8 inch) wall, linepipe. The experiments were carried out at the NRU reactor, Chalk River using the L3 triple-axis spectrometer. The through-wall distribution of axial residual strain was measured at 0, 4, 8, 20 and 50 mm from the weld centerline; the axial variation was determined 1, 5, 8, and 13 mm from the inside surface of the pipe wall. The results have been compared with strain gauge measurements on the weld surface and with through-wall residual stress distributions determined using the block-layering and removal technique

  9. Engineering related neutron diffraction measurements probing strains, texture and microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Clausen, Bjorn [Los Alamos National Laboratory; Brown, Donald W [Los Alamos National Laboratory; Tome, Carlos N [Los Alamos National Laboratory; Balogh, Levente [Los Alamos National Laboratory; Vogel, Sven C [Los Alamos National Laboratory

    2010-01-01

    Neutron diffraction has been used for engineering applications for nearly three decades. The basis of the technique is powder diffraction following Bragg's Law. From the measured diffraction patterns information about internal, or residual, strain can be deduced from the peak positions, texture information can be extracted from the peak intensities, and finally the peak widths can provide information about the microstructure, e.g. dislocation densities and grain sizes. The strains are measured directly from changes in lattice parameters, however, in many cases it is non-trivial to determine macroscopic values of stress or strain from the measured data. The effects of intergranular strains must be considered, and combining the neutron diffraction measurements with polycrystal deformation modeling has proven invaluable in determining the overall stress and strain values of interest in designing and dimensioning engineering components. Furthelmore, the combined use of measurements and modeling has provided a tool for elucidating basic material properties, such as critical resolved shear stresses for the active deformation modes and their evolution as a function of applied deformation.

  10. Strain measurements of the tibial insert of a knee prosthesis using a knee motion simulator.

    Science.gov (United States)

    Sera, Toshihiro; Iwai, Yuya; Yamazaki, Takaharu; Tomita, Tetsuya; Yoshikawa, Hideki; Naito, Hisahi; Matsumoto, Takeshi; Tanaka, Masao

    2017-12-01

    The longevity of a knee prosthesis is influenced by the wear of the tibial insert due to its posture and movement. In this study, we assumed that the strain on the tibial insert is one of the main reasons for its wear and investigated the influence of the knee varus-valgus angles on the mechanical stress of the tibial insert. Knee prosthesis motion was simulated using a knee motion simulator based on a parallel-link six degrees-of-freedom actuator and the principal strain and pressure distribution of the tibial insert were measured. In particular, the early stance phase obtained from in vivo X-ray images was examined because the knee is applied to the largest load during extension/flexion movement. The knee varus-valgus angles were 0° (neutral alignment), 3°, and 5° malalignment. Under a neutral orientation, the pressure was higher at the middle and posterior condyles. The first and second principal strains were larger at the high and low pressure areas, respectively. Even for a 3° malalignment, the load was concentrated at one condyle and the positive first principal strain increased dramatically at the high pressure area. The negative second principal strain was large at the low pressure area on the other condyle. The maximum equivalent strain was 1.3-2.1 times larger at the high pressure area. For a 5° malalignment, the maximum equivalent strain increased slightly. These strain and pressure measurements can provide the mechanical stress of the tibial insert in detail for determining the longevity of an artificial knee joint.

  11. Electro optical system to measure strains at high temperature

    Science.gov (United States)

    Sciammarella, Cesar A.

    1991-12-01

    The measurement of strains at temperatures of the order of 1000 C has become a very important field of research. Technological advances in areas such as the analysis of high speed aircraft structures and high efficiency thermal engines require operational temperatures of this order of magnitude. Current techniques for the measurement of strains, such as electrical strain gages, are at the limit of their useful range and new methods need to be developed. Optical techniques are very attractive in this type of application because of their noncontacting nature. Holography is of particular interest because a minimal preparation of the surfaces is required. Optoelectronics holography is specially suited for this type of application, from the point of view of industrial use. There are a number of technical problems that need to be overcome to measure strains using holographic interferometry at high temperatures. Some of these problems are discussed, and solutions are given. A specimen instrumented with high temperature strains gages is used to compare the results of both technologies.

  12. Pilot study on rugged fiber optic brillouin sensors for large-strain measurements to ensure the safety of transportation structures.

    Science.gov (United States)

    2012-07-01

    Brillouin-scattering Optical Time Domain Reflectometry (BOTDR) is a viable technology for simultaneous, distributed : strain and temperature measurements for miles-long transportation structures. It is a promising tool to ensure the smooth : operatio...

  13. The application of a 3 dimensional image scanner to the strain measurement

    International Nuclear Information System (INIS)

    Mazda, Taiji; Ogawa, Hiroshi; Suzuki, Michiaki; Nakano, Yasuo.

    1993-01-01

    A large strain measuring method for a laminated seismic isolation rubber, which will be introduced to reactor buildings of the Demonstration Fast Breeder Reactor (DFBR), was developed. With using strain gages, it is difficult to measure the large strain under the large displacement condition. With using the optical instruments, it is also impossible to measure the strain of a 3 dimensional object. We developed a new measuring method in which strain is calculated from a 3 dimensional deformation with using a 3 dimensional image scanner. This method is noncontact measuring method, and it can measure the strain of a 3 dimensional object under the large deformation. This work is one part of 'The Development of FBR Seismic Isolation system' operated by Central Research Institute of Electric Power Industry. (author)

  14. A new strain gage method for measuring the contractile strain ratio of Zircaloy tubing

    International Nuclear Information System (INIS)

    Hwang, S.K.; Sabol, G.P.

    1988-01-01

    An improved strain gage method for determining the contractile strain ratio (CSR) of Zircaloy tubing was developed. The new method consists of a number of load-unload cyclings at approximately 0.2% plastic strain interval. With this method the CSR of Zircaloy-4 tubing could be determined accurately because it was possible to separate the plastic strains from the elastic strain involvement. The CSR values determined by use of the new method were in good agreement with those calculated from conventional post-test manual measurements. The CSR of the tubing was found to decrease with the amount of deformation during testing because of uneven plastic flow in the gage section. A new technique of inscribing gage marks by use of a YAG laser is discussed. (orig.)

  15. Data transfer of structural strain by wireless device

    International Nuclear Information System (INIS)

    Kim, Chi Yeop; Kwon, Il Bum; Choi, Man Yong

    2002-01-01

    The wireless measurement device was instrumented to measure the stress distribution of structures. This device was composed of the data recorder, transmitter and receiver with PC interface. The specification of this device was as follows: Analog inputs of 8 channels, 400 MHz transmitted frequency, and the transmitted power of 5 mW. This device was manufactured as the sending and receiving system of long-term strains to calculate the stress distribution. The 4 channel strains of 150 Hz were well transmitted by this device. Also, these strain data was able to show the stress distribution of the experimental specimen. Furthermore, the data quantity was equal to the data quantity during three months at 1 hour sampling time

  16. Strain Measurement System Developed for Biaxially Loaded Cruciform Specimens

    Science.gov (United States)

    Krause, David L.

    2000-01-01

    A new extensometer system developed at the NASA Glenn Research Center at Lewis Field measures test area strains along two orthogonal axes in flat cruciform specimens. This system incorporates standard axial contact extensometers to provide a cost-effective high-precision instrument. The device was validated for use by extensive testing of a stainless steel specimen, with specimen temperatures ranging from room temperature to 1100 F. In-plane loading conditions included several static biaxial load ratios, plus cyclic loadings of various waveform shapes, frequencies, magnitudes, and durations. The extensometer system measurements were compared with strain gauge data at room temperature and with calculated strain values for elevated-temperature measurements. All testing was performed in house in Glenn's Benchmark Test Facility in-plane biaxial load frame.

  17. Isolation and purification of Gallid herpesvirus 2 strains currently distributed in Japan.

    Science.gov (United States)

    Machida, Yuka; Murata, Shiro; Matsuyama-Kato, Ayumi; Isezaki, Masayoshi; Taneno, Akira; Sakai, Eishi; Konnai, Satoru; Ohashi, Kazuhiko

    2017-01-20

    Gallid herpesvirus 2 (GaHV-2) causes malignant lymphomas in chickens (Marek's disease, MD). Although MD is controlled through vaccination efforts, field isolates of GaHV-2 have increased in virulence worldwide and even cause MD in vaccinated chickens. GaHV-2 strains are classified into four categories (mild, virulent, very virulent and very virulent +) based on the virulence exhibited in experimental infection in unvaccinated or MD-vaccinated susceptible chickens. Although MD cases are sporadically reported in Japan, the recent field strains of GaHV-2 in Japan have not been characterized. During isolation of recent field strains by using primary chicken kidney cell cultures, a method classically used for GaHV-2 isolation, vaccine strains were simultaneously isolated. Therefore, it is necessary to separate vaccine strains to characterize the virulence and pathogenicity of the GaHV-2 strains currently distributed in Japan. In this study, we prepared cell suspensions from the spleens of MD-symptomatic chickens, inoculated day-old-chicks and isolated GaHV-2 strains by primary chicken kidney cell cultures at 2-3 weeks post inoculation. The isolated strains were passaged several times on chicken embryo fibroblast cells, and PCR analysis revealed that the isolated strains were not contaminated with vaccine strains. Moreover, the contaminant vaccine strains were completely removed by the purification of plaques observed in chicken kidney cells. These procedures are necessary to isolate GaHV-2 field strains from vaccine strains in order to carry out future studies to characterize these strains and glean insights into GaHV-2 virulence and pathogenicity.

  18. The influence of microstructure on surface strain distributions in a nickel micro-tension specimen

    International Nuclear Information System (INIS)

    Turner, T J; Shade, P A; Schuren, J C; Groeber, M A

    2013-01-01

    This work presents an integrated experimental and modeling approach for examining the deformation of a pure nickel polycrystal utilizing micro-mechanical testing and a crystal-based elasto-viscoplastic finite-element model (CPFEM). The objective is to study the influence of microstructure on the heterogeneous deformation in polycrystalline materials, and to utilize a modeling framework to explore aspects of the deformation that are difficult or impossible to measure experimentally. To accomplish this, a micro-tension specimen containing 259 grains was created from a pure nickel foil material and deformed in uniaxial tension. After the deformation, the specimen was destructively serial sectioned in concert with electron back scattering diffraction, and these data were used to instantiate a CPFEM simulation. The material parameters in the CPFEM model were calibrated by matching the experimental macroscopic stress-strain response of the micro-tension specimen, and then the simulation results were compared with experimental surface deformations measured with digital image correlation. After validating the simulation results by comparing measured and predicted surface strain distributions, a parametric study of the influence of both crystallographic texture and grain morphology is presented to better understand the influence of microstructure on the development of heterogeneous deformation in the pure nickel polycrystalline material. (paper)

  19. The mechanical behavior of metal alloys with grain size distribution in a wide range of strain rates

    Science.gov (United States)

    Skripnyak, V. A.; Skripnyak, V. V.; Skripnyak, E. G.

    2017-12-01

    The paper discusses a multiscale simulation approach for the construction of grain structure of metals and alloys, providing high tensile strength with ductility. This work compares the mechanical behavior of light alloys and the influence of the grain size distribution in a wide range of strain rates. The influence of the grain size distribution on the inelastic deformation and fracture of aluminium and magnesium alloys is investigated by computer simulations in a wide range of strain rates. It is shown that the yield stress depends on the logarithm of the normalized strain rate for light alloys with a bimodal grain distribution and coarse-grained structure.

  20. A production of non-strain spacing of lattice planes measurement equipment and a measurement of general structure material

    International Nuclear Information System (INIS)

    Minakawa, Nobuaki; Moriai, Atsushi; Morii, Yukio

    2001-01-01

    It is necessary to determine Δd/d in the internal stress measurement by the neutron diffraction method. Therefore, in case the non-strain spacing of lattice planes d 0 (hkl) is measured using bulk material, even though it does and attaches in a sample table length or every width and it is performing the diffraction measurement, it is difficult to determine for a true non-strain spacing of lattice planes by a processing strain, the grain-orientation, etc. It is available for the infinite thing spacing of lattice planes near non-strain condition to be measured by doing random rotation for bulk material in a beam center, and measuring an average spacing of lattice planes. Practical non-strain spacing of lattice planes measurement equipment was made, and the measurement was performed about much structure material. (author)

  1. Measuring systolic ankle and toe pressure using the strain gauge technique--a comparison study between mercury and indium-gallium strain gauges

    DEFF Research Database (Denmark)

    Broholm, Rikke; Wiinberg, Niels; Simonsen, Lene

    2014-01-01

    BACKGROUND: Measurement of the ankle and toe pressures are often performed using a plethysmograph, compression cuffs and a strain gauge. Usually, the strain gauge contains mercury but other alternatives exist. From 2014, the mercury-containing strain gauge will no longer be available in the Europ......BACKGROUND: Measurement of the ankle and toe pressures are often performed using a plethysmograph, compression cuffs and a strain gauge. Usually, the strain gauge contains mercury but other alternatives exist. From 2014, the mercury-containing strain gauge will no longer be available...... in the European Union. The aim of this study was to compare an indium-gallium strain gauge to the established mercury-containing strain gauge. METHODS: Consecutive patients referred to the Department of Clinical Physiology and Nuclear Medicine at Bispebjerg and Frederiksberg Hospitals for measurements of systolic...... ankle and toe pressures volunteered for the study. Ankle and toe pressures were measured twice with the mercury and the indium-gallium strain gauge in random order. Comparison of the correlation between the mean pressure using the mercury and the indium-gallium device and the difference between the two...

  2. Effects of Shape and Strain Distribution of Quantum Dots on Optical Transition in the Quantum Dot Infrared Photodetectors

    Directory of Open Access Journals (Sweden)

    Fu Y

    2008-01-01

    Full Text Available Abstract We present a systemic theoretical study of the electronic properties of the quantum dots inserted in quantum dot infrared photodetectors (QDIPs. The strain distribution of three different shaped quantum dots (QDs with a same ratio of the base to the vertical aspect is calculated by using the short-range valence-force-field (VFF approach. The calculated results show that the hydrostatic strain ɛHvaries little with change of the shape, while the biaxial strain ɛBchanges a lot for different shapes of QDs. The recursion method is used to calculate the energy levels of the bound states in QDs. Compared with the strain, the shape plays a key role in the difference of electronic bound energy levels. The numerical results show that the deference of bound energy levels of lenslike InAs QD matches well with the experimental results. Moreover, the pyramid-shaped QD has the greatest difference from the measured experimental data.

  3. Raman measurements of Kevlar-29 fiber pull-out test at different strain levels

    Science.gov (United States)

    Wang, Quan; Lei, Zhenkun; Kang, Yilan; Qiu, Wei

    2008-11-01

    This paper adopted Kevlar-29 fiber monofilament embedding technology to prepare fiber/ epoxy resin tensile specimen. The specimen was pulled on a homemade and portable mini-loading device. At the same time micro-Raman spectroscopy is introduced to detect the distributions of stress on the embedded fiber at different strain levels. The characteristic peak shift of the 1610 cm-1 in Raman band has a linear relationship with the strain or stress. The experimental results show that the fiber axial stress decreases gradually from the embedded fiber-start to the embedded fiber-end at the same strain level. At different strain levels, the fiber axial stress increases along with the applied load. It reveals that there is a larger fiber axial stress distribution under a larger strain level. And the stress transfer is realized gradually from the embedded fiber-start to the fiber-end. Stress concentration exists in the embedded fiber-end, which is a dangerous region for interfacial debonding easily.

  4. Development of shearography for surface strain measurement of non planar objects

    International Nuclear Information System (INIS)

    Groves, Roger Michael

    2001-01-01

    The subject of this thesis is the development of optical instrumentation for surface strain measurement of non-planar objects. The speckle interferometry technique of shearography is used to perform quantitative measurements of surface strain on non-planar objects and to compensate these measurements for the errors that are due to the shape and slope of the object. Shearography is an optical technique that is usually used for defect location and for qualitative strain characterisation. In this thesis a multi-component shearography system is described that can measure the six components of displacement gradient. From these measurements the surface strain can be fully characterised. For non-planar objects an error is introduced into the displacement gradient measurement due to the variation of the sensitivity vector across the field of view and the variation in the magnitude of applied shear due to the curvature of the object surface. To correct for these errors requires a knowledge of the slope and shape of the object. Shearography may also be used to measure object slope and shape by a source displacement technique. Therefore slope, shape and surface strain may be measured using the same optical system. The thesis describes a method of multiplexing the shear direction using polarisation switching, a method of measuring the source position using shadow Moire and the shearography source displacement technique for measuring the surface slope and shape of objects. The multi-component shearography system is used to perform measurements of the six components of surface strain, on an industrial component, with a correction applied for errors due to the shape and slope of the object. (author)

  5. Quantification of the spatial strain distribution of scoliosis using a thin-plate spline method.

    Science.gov (United States)

    Kiriyama, Yoshimori; Watanabe, Kota; Matsumoto, Morio; Toyama, Yoshiaki; Nagura, Takeo

    2014-01-03

    The objective of this study was to quantify the three-dimensional spatial strain distribution of a scoliotic spine by nonhomogeneous transformation without using a statistically averaged reference spine. The shape of the scoliotic spine was determined from computed tomography images from a female patient with adolescent idiopathic scoliosis. The shape of the scoliotic spine was enclosed in a rectangular grid, and symmetrized using a thin-plate spline method according to the node positions of the grid. The node positions of the grid were determined by numerical optimization to satisfy symmetry. The obtained symmetric spinal shape was enclosed within a new rectangular grid and distorted back to the original scoliotic shape using a thin-plate spline method. The distorted grid was compared to the rectangular grid that surrounded the symmetrical spine. Cobb's angle was reduced from 35° in the scoliotic spine to 7° in the symmetrized spine, and the scoliotic shape was almost fully symmetrized. The scoliotic spine showed a complex Green-Lagrange strain distribution in three dimensions. The vertical and transverse compressive/tensile strains in the frontal plane were consistent with the major scoliotic deformation. The compressive, tensile and shear strains on the convex side of the apical vertebra were opposite to those on the concave side. These results indicate that the proposed method can be used to quantify the three-dimensional spatial strain distribution of a scoliotic spine, and may be useful in quantifying the deformity of scoliosis. © 2013 Elsevier Ltd. All rights reserved.

  6. Comparison of Measured Residual Stress in an Extra Thick Multi-pass Weld Using Neutron Diffraction Method and Inherent Strain Method

    International Nuclear Information System (INIS)

    Park, JeongUng; An, GyuBaek; Woo, Wan Chuck

    2015-01-01

    With the increase of large-scale containership, a large amount of high-strength steels with extra thick plates is being extensively used. The welding stress existing in the extra thick welded plates has a significant effect on the integrity of the component in terms of brittle fracture and fatigue behavior. It has been reported that welding residual stress distribution in an extra thick plate can affect the propagation path of the crack. Therefore, it is important to measure the distribution of welding residual stresses for the reliable design of the welded structures. So far various researches have been carried out for the determination of residual stresses on the surface of steels. In this paper, the total residual stresses in the 70 mm thick multipass FACW butt joint were measured by integrating initial stress into ISM. Concretely, two methods named as initial stress integrated ISM and initial inherent strain integrated ISM were employed to determine the total residual stresses. Furthermore, the distributions of residual stresses were compared with the results of the Neutron Diffraction Method(NDM). In order to measure the three dimensional residual stresses in the welded joint with initial stresses existing before welding, initial stress integrated ISM and initial inherent strain integrated ISM were developed. The residual stresses in 70 mm-thick butt joint by flux cored arc welding were carried out with a good accuracy using the two developed methods. The residual stresses in welded joint using both initial stress integrated ISM and initial inherent strain integrated ISM agreed well with the results measured by Neutron Diffraction Method. This suggests that the integrated ISM is a reliable method for residual stress measurement if initial stress existed

  7. From Measurements Errors to a New Strain Gauge Design

    DEFF Research Database (Denmark)

    Mikkelsen, Lars Pilgaard; Zike, Sanita; Salviato, Marco

    2015-01-01

    Significant over-prediction of the material stiffness in the order of 1-10% for polymer based composites has been experimentally observed and numerical determined when using strain gauges for strain measurements instead of non-contact methods such as digital image correlation or less stiff method...

  8. Strain Distribution of Au and Ag Nanoparticles Embedded in Al2O3 Thin Film

    Directory of Open Access Journals (Sweden)

    Honghua Huang

    2014-01-01

    Full Text Available Au and Ag nanoparticles embedded in amorphous Al2O3 matrix are fabricated by the pulsed laser deposition (PLD method and rapid thermal annealing (RTA technique, which are confirmed by the experimental high-resolution transmission electron microscope (HRTEM results, respectively. The strain distribution of Au and Ag nanoparticles embedded in the Al2O3 matrix is investigated by the finite-element (FE calculations. The simulation results clearly indicate that both the Au and Ag nanoparticles incur compressive strain by the Al2O3 matrix. However, the compressive strain existing on the Au nanoparticle is much weaker than that on the Ag nanoparticle. This phenomenon can be attributed to the reason that Young’s modulus of Au is larger than that of Ag. This different strain distribution of Au and Ag nanoparticles in the same host matrix may have a significant influence on the technological potential applications of the Au-Ag alloy nanoparticles.

  9. Revealing differences in metabolic flux distributions between a mutant strain and its parent strain Gluconacetobacter xylinus CGMCC 2955.

    Directory of Open Access Journals (Sweden)

    Cheng Zhong

    Full Text Available A better understanding of metabolic fluxes is important for manipulating microbial metabolism toward desired end products, or away from undesirable by-products. A mutant strain, Gluconacetobacter xylinus AX2-16, was obtained by combined chemical mutation of the parent strain (G. xylinus CGMCC 2955 using DEC (diethyl sulfate and LiCl. The highest bacterial cellulose production for this mutant was obtained at about 11.75 g/L, which was an increase of 62% compared with that by the parent strain. In contrast, gluconic acid (the main byproduct concentration was only 5.71 g/L for mutant strain, which was 55.7% lower than that of parent strain. Metabolic flux analysis indicated that 40.1% of the carbon source was transformed to bacterial cellulose in mutant strain, compared with 24.2% for parent strain. Only 32.7% and 4.0% of the carbon source were converted into gluconic acid and acetic acid in mutant strain, compared with 58.5% and 9.5% of that in parent strain. In addition, a higher flux of tricarboxylic acid (TCA cycle was obtained in mutant strain (57.0% compared with parent strain (17.0%. It was also indicated from the flux analysis that more ATP was produced in mutant strain from pentose phosphate pathway (PPP and TCA cycle. The enzymatic activity of succinate dehydrogenase (SDH, which is one of the key enzymes in TCA cycle, was 1.65-fold higher in mutant strain than that in parent strain at the end of culture. It was further validated by the measurement of ATPase that 3.53-6.41 fold higher enzymatic activity was obtained from mutant strain compared with parent strain.

  10. Measurement of the uniaxial mechanical properties of rat skin using different stress-strain definitions.

    Science.gov (United States)

    Karimi, A; Navidbakhsh, M

    2015-05-01

    The mechanical properties of skin tissue may vary according to the anatomical locations of a body. There are different stress-strain definitions to measure the mechanical properties of skin tissue. However, there is no agreement as to which stress-strain definition should be implemented to measure the mechanical properties of skin at different anatomical locations. Three stress definitions (second Piola-Kichhoff stress, engineering stress, and true stress) and four strain definitions (Almansi-Hamel strain, Green-St. Venant strain, engineering strain, and true strain) are employed to determine the mechanical properties of skin tissue at back and abdomen locations of a rat body. The back and abdomen skins of eight rats are excised and subjected to a series of tensile tests. The elastic modulus, maximum stress, and strain of skin tissues are measured using three stress definitions and four strain definitions. The results show that the effect of varying the stress definition on the maximum stress measurements of the back skin is significant but not when calculating the elastic modulus and maximum strain. No significant effects are observed on the elastic modulus, maximum stress, and strain measurements of abdomen skin by varying the stress definition. In the true stress-strain diagram, the maximum stress (20%), and elastic modulus (35%) of back skin are significantly higher than that of abdomen skin. The true stress-strain definition is favored to measure the mechanical properties of skin tissue since it gives more accurate measurements of the skin's response using the instantaneous values. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Strain distribution of confined Ge/GeO2 core/shell nanoparticles engineered by growth environments

    Science.gov (United States)

    Wei, Wenyan; Yuan, Cailei; Luo, Xingfang; Yu, Ting; Wang, Gongping

    2016-02-01

    The strain distributions of Ge/GeO2 core/shell nanoparticles confined in different host matrix grown by surface oxidation are investigated. The simulated results by finite element method demonstrated that the strains of the Ge core and the GeO2 shell strongly depend on the growth environments of the nanoparticles. Moreover, it can be found that there is a transformation of the strain on Ge core from tensile to compressive strain during the growth of Ge/GeO2 core/shell nanoparticles. And, the transformation of the strain is closely related with the Young's modulus of surrounding materials of Ge/GeO2 core/shell nanoparticles.

  12. Development of a quick and easy-to-install strain measurement tool for piping stress evaluation

    International Nuclear Information System (INIS)

    Takahama, Tsunemichi; Nishimura, Kazuma; Ninomiya, Seiichiro; Matsumoto, Yoshihiro; Harada, Yutaka

    2015-01-01

    To avoid failures of small bore piping connections caused by high cycle fatigue, it is important to measure the stresses around the connections. To measure such stresses, the authors have developed an easily-attachable and detachable strain measurement tool which utilizes strain gauges in combination with our patented strain gauge holder. Traditionally, strain gauges have been bonded to piping surfaces using adhesive; however, with the newly-developed measurement tool, bonding adhesive is no longer necessary. The tool can be installed quickly and easily on a piping surface and measure the strains on the piping as accurately as adhesively-bonded strain gauges. Accordingly, the new strain measurement tool significantly reduces the work time without affecting the measurement accuracy. (author)

  13. Hybrid MEFPI/FBG sensor for simultaneous measurement of strain and magnetic field

    Science.gov (United States)

    Chen, Mao-qing; Zhao, Yong; Lv, Ri-qing; Xia, Feng

    2017-12-01

    A hybrid fiber-optic sensor consisting of a micro extrinsic Fabry-Perot Interferometer (MEFPI) and an etched fiber Bragg grating (FBG) is proposed, which can measure strain and magnetic field simultaneously. The etched FBG is sealed in a capillary with ferrofluids to detect the surrounding magnetic field. FBG with small diameter will be more sensitive to magnetic field is confirmed by simulation results. The MEFPI sensor that is prepared through welding a short section of hollow-core fiber (HCF) with single-mode fiber (SMF) is effective for strain detection. The experiment shows that strain and magnetic field can be successfully simultaneously detected based on hybrid MEFPI/FBG sensor. The sensitivities of the strain and magnetic field intensity are measured to be up to 1.41 pm/με and 5.11 pm/mT respectively. There is a negligible effect on each other, hence simultaneously measuring strain and magnetic field is feasible. It is anticipated that such easy preparation, compact and low-cost fiber-optic sensors for simultaneous measurement of strain and magnetic field could find important applications in practice.

  14. Increasing Accuracy of Tissue Shear Modulus Reconstruction Using Ultrasonic Strain Tensor Measurement

    Science.gov (United States)

    Sumi, C.

    Previously, we developed three displacement vector measurement methods, i.e., the multidimensional cross-spectrum phase gradient method (MCSPGM), the multidimensional autocorrelation method (MAM), and the multidimensional Doppler method (MDM). To increase the accuracies and stabilities of lateral and elevational displacement measurements, we also developed spatially variant, displacement component-dependent regularization. In particular, the regularization of only the lateral/elevational displacements is advantageous for the lateral unmodulated case. The demonstrated measurements of the displacement vector distributions in experiments using an inhomogeneous shear modulus agar phantom confirm that displacement-component-dependent regularization enables more stable shear modulus reconstruction. In this report, we also review our developed lateral modulation methods that use Parabolic functions, Hanning windows, and Gaussian functions in the apodization function and the optimized apodization function that realizes the designed point spread function (PSF). The modulations significantly increase the accuracy of the strain tensor measurement and shear modulus reconstruction (demonstrated using an agar phantom).

  15. Polymer film strain gauges for measuring large elongations

    Science.gov (United States)

    Kondratov, A. P.; Zueva, A. M.; Varakin, R. S.; Taranec, I. P.; Savenkova, I. A.

    2018-02-01

    The paper shows the possibility to print polymer strain gages, microstrip lines, coplanar waveguides, and other prints for avionics using printing technology and equipment. The methods of screen and inkjet printing have been complemented by three new operations of preparing print films for application of an electrically conductive ink layer. Such additional operations make it possible to enhance the conductive ink layer adhesion to the film and to manufacture strain gages for measuring large elongations.

  16. Damage identification method for continuous girder bridges based on spatially-distributed long-gauge strain sensing under moving loads

    Science.gov (United States)

    Wu, Bitao; Wu, Gang; Yang, Caiqian; He, Yi

    2018-05-01

    A novel damage identification method for concrete continuous girder bridges based on spatially-distributed long-gauge strain sensing is presented in this paper. First, the variation regularity of the long-gauge strain influence line of continuous girder bridges which changes with the location of vehicles on the bridge is studied. According to this variation regularity, a calculation method for the distribution regularity of the area of long-gauge strain history is investigated. Second, a numerical simulation of damage identification based on the distribution regularity of the area of long-gauge strain history is conducted, and the results indicate that this method is effective for identifying damage and is not affected by the speed, axle number and weight of vehicles. Finally, a real bridge test on a highway is conducted, and the experimental results also show that this method is very effective for identifying damage in continuous girder bridges, and the local element stiffness distribution regularity can be revealed at the same time. This identified information is useful for maintaining of continuous girder bridges on highways.

  17. Assessing the small-strain soil stiffness for offshore wind turbines based on in situ seismic measurements

    International Nuclear Information System (INIS)

    Versteijlen, W G; Van Dalen, K N; Metrikine, A V; Hamre, L

    2014-01-01

    The fundamental natural frequency as measured on installed offshore wind turbines is significantly higher than its designed value, and it is expected that the explanation for this can be found in the currently adopted modeling of soil-structure interaction. The small-strain soil stiffness is an important design parameter, as it has a defining influence on the first natural frequency of these structures. In this contribution, in situ seismic measurements are used to derive the small-strain shear modulus of soil as input for 3D soil-structure interaction models to assess the initial soil stiffness at small strains for offshore wind turbine foundations. A linear elastic finite element model of a half-space of solids attached to a pile is used to derive an equivalent first mode shape of the foundation. The second model extends the first one by introducing contact elements between pile and soil, to take possible slip and gap-forming into account. The deflections derived with the 3D models are smaller than those derived with the p- y curve design code. This higher stiffness is in line with the higher measured natural frequencies. Finally a method is suggested to translate the response of 3D models into 1D engineering models of a beam laterally supported by uncoupled distributed springs

  18. Measurement of strains by means of electro-optics holography

    Science.gov (United States)

    Sciammarella, Cesar A.; Bhat, Gopalakrishna K.; Albertazzi, Armando, Jr.

    1991-03-01

    The use of a TV camera as a recording medium and the observation of whole field displacements in real time makes holographic TV a very interesting and powerful tool in a variety of areas from NDE to research and development. The paper presents new developments in the field that add to the versatility of the technique by introducing portability and methods to obtain accurate quantitative results. Examples of applications are given to the measurement of strains both at room and at high temperatures and strain measurements at the microscopic level. 1.

  19. Technique for measurements of plane waves of uniaxial strain

    International Nuclear Information System (INIS)

    Graham, R.A.

    1977-01-01

    The measurement of plane waves in uniaxial strain, in which large surface areas are loaded and the measurements are restricted to a central region that is not influenced by lateral boundaries, is discussed. Measuring techniques are covered and instruments are discussed

  20. Controlling charges distribution at the surface of a single GaN nanowire by in-situ strain

    Directory of Open Access Journals (Sweden)

    Xiao Chen

    2017-08-01

    Full Text Available Effect of the strain on the charge distribution at the surface of a GaN semiconductor nanowire (NW has been investigated inside transmission electron microscope (TEM by in-situ off-axis electron holography. The outer and inner surfaces of the NW bent axially under compression of two Au electrodes were differently strained, resulting in difference of their Fermi levels. Consequently, the free electrons flow from the high Fermi level to the low level until the two Fermi levels aligned in a line. The potential distributions induced by charge redistribution in the two vacuum sides of the bent NW were examined respectively, and the opposite nature of the bounded charges on the outer and inner surfaces of the bent NW was identified. The results provide experimental evidence that the charge distribution at the surfaces of a single GaN NW can be controlled by different strains created along the NW.

  1. Synchrotron X-ray measurement of residual strain within the nose of a worn manganese steel railway crossing

    Science.gov (United States)

    Dhar, S.; Zhang, Y.; Xu, R.; Danielsen, HK; Jensen, D. Juul

    2017-07-01

    Switches and crossings are an integral part of any railway network. Plastic deformation associated with wear and rolling contact fatigue due to repeated passage of trains cause severe damage leading to the formation of surface and sub-surface cracks which ultimately may result in rail failure. Knowledge of the internal stress distribution adds to the understanding of crack propagation and may thus help to prevent catastrophic rail failures. In this work, the residual strains inside the bulk of a damaged nose of a manganese railway crossing that was in service for five years has been investigated by using differential aperture synchrotron X-ray diffraction. The main purpose of this paper is to describe how this method allows non-destructive measurement of residual strains in selected local volumes in the bulk of the rail. Measurements were conducted on the transverse surface at a position about 6.5 mm from the rail running surface of a crossing nose. The results revealed the presence of significant compressive residual strains along the running direction of the rail.

  2. Stress strain tensors with their application to x-ray stress measurement

    International Nuclear Information System (INIS)

    Kurita, Masanori

    2015-01-01

    This paper describes in detail the method of obtaining the formulas of stress-strain tensor that express the directional dependence of stress-strain, that is, how these values change in response to coordinate transformation, and clarifies the preconditions for supporting both formulas. The two conversion formulas are both the second order of tensor, and the formula of strain tensor not only does not use the relational expression of stress and strain at all, but also is obtained completely independently of the formula of stress tensor. Except for the condition that the strain is very small (elastic deformation) in the conversion formula of strain, both formulas unconditionally come into effect. In other words, both formulas hold true even in the isotropic elastic body or anisotropic elastic body. It was shown that the conversion formula of strain can be derived from the conversion formula of stress using the formula of Hooke for isotropic elastic body. From these three-dimensional expressions, the two-dimensional stress-strain coordinate conversion formula that is used for Mohr's stress-strain circle was derived. It was shown that these formulas hold true for three-dimensional stress condition with stress-strain components in the three-axial direction that are not plane stress nor plane strain condition. In addition, as an application case of this theory, two-dimensional and three-dimensional X-ray stress measurements that are effective for residual stress measurement were shown. (A.O.)

  3. Residual stress distribution in carbon steel pipe welded joint measured by neutron diffraction

    International Nuclear Information System (INIS)

    Hayashi, Makoto; Ishiwata, Masayuki; Morii, Yukio; Minakawa, Nobuaki

    2000-01-01

    In order to estimate crack growth behavior of fatigue and stress corrosion cracking in pipes, the residual stress distribution near the pipe weld region has to be measured through the wall thickness. Since the penetration depth of neutron is deep enough to pass through the thick pipe wall, the neutron diffraction technique for the residual stress measurement is effective for this purpose. At the first step the residual stress distribution near the weld region in a butt-welded carbon steel pipe was measured by the neutron diffraction. Significant stresses extended only to a distance of 30 mm from the center of the weld. The major tensile stresses occurred in the hoop direction in the fusion and heat affected zones of the weldment, and they attained a level greater than 200 MPa through the thickness. While the axial residual stress at the inside surface was 50 MPa, the stress at the outside surface was -100 MPa. The comparison of residual stress distributions measured by the neutron diffraction, the X-ray diffraction and the strain gauge method reveals that the neutron diffraction is the most effective for measuring the residual stress inside the structural components. (author)

  4. Role of Prion Replication in the Strain-dependent Brain Regional Distribution of Prions.

    Science.gov (United States)

    Hu, Ping Ping; Morales, Rodrigo; Duran-Aniotz, Claudia; Moreno-Gonzalez, Ines; Khan, Uffaf; Soto, Claudio

    2016-06-10

    One intriguing feature of prion diseases is their strain variation. Prion strains are differentiated by the clinical consequences they generate in the host, their biochemical properties, and their potential to infect other animal species. The selective targeting of these agents to specific brain structures have been extensively used to characterize prion strains. However, the molecular basis dictating strain-specific neurotropism are still elusive. In this study, isolated brain structures from animals infected with four hamster prion strains (HY, DY, 139H, and SSLOW) were analyzed for their content of protease-resistant PrP(Sc) Our data show that these strains have different profiles of PrP deposition along the brain. These patterns of accumulation, which were independent of regional PrP(C) production, were not reproduced by in vitro replication when different brain regions were used as substrate for the misfolding-amplification reaction. On the contrary, our results show that in vitro replication efficiency depended exclusively on the amount of PrP(C) present in each part of the brain. Our results suggest that the variable regional distribution of PrP(Sc) in distinct strains is not determined by differences on prion formation, but on other factors or cellular pathways. Our findings may contribute to understand the molecular mechanisms of prion pathogenesis and strain diversity. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. In operando X-ray diffraction strain measurement in Ni3Sn2 - Coated inverse opal nanoscaffold anodes for Li-ion batteries

    Science.gov (United States)

    Glazer, Matthew P. B.; Wang, Junjie; Cho, Jiung; Almer, Jonathan D.; Okasinski, John S.; Braun, Paul V.; Dunand, David C.

    2017-11-01

    Volume changes associated with the (de)lithiation of a nanostructured Ni3Sn2 coated nickel inverse opal scaffold anode create mismatch stresses and strains between the Ni3Sn2 anode material and its mechanically supporting Ni scaffold. Using in operando synchrotron x-ray diffraction measurements, elastic strains in the Ni scaffold are determined during cyclic (dis)charging of the Ni3Sn2 anode. These strains are characterized using both the center position of the Ni diffraction peaks, to quantify the average strain, and the peak breadth, which describes the distribution of strain in the measured volume. Upon lithiation (half-cell discharging) or delithiation (half-cell charging), compressive strains and peak breadth linearly increase or decrease, respectively, with charge. The evolution of the average strains and peak breadths suggests that some irreversible plastic deformation and/or delamination occurs during cycling, which can result in capacity fade in the anode. The strain behavior associated with cycling of the Ni3Sn2 anode is similar to that observed in recent studies on a Ni inverse-opal supported amorphous Si anode and demonstrates that the (de)lithiation-induced deformation and damage mechanisms are likely equivalent in both anodes, even though the magnitude of mismatch strain in the Ni3Sn2 is lower due to the lower (de)lithiation-induced contraction/expansion.

  6. Local, atomic-level elastic strain measurements of metallic glass thin films by electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Ebner, C. [Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria); Sarkar, R. [Department of Materials Science and Engineering, School for Engineering of Matter Transport and Energy, Arizona State University, Tempe 85287 (United States); Rajagopalan, J. [Department of Materials Science and Engineering, School for Engineering of Matter Transport and Energy, Arizona State University, Tempe 85287 (United States); Department of Mechanical and Aerospace Engineering, School for Engineering of Matter Transport and Energy, Arizona State University, Tempe 85287 (United States); Rentenberger, C., E-mail: christian.rentenberger@univie.ac.at [Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria)

    2016-06-15

    A novel technique is used to measure the atomic-level elastic strain tensor of amorphous materials by tracking geometric changes of the first diffuse ring of selected area electron diffraction patterns (SAD). An automatic procedure, which includes locating the centre and fitting an ellipse to the diffuse ring with sub-pixel precision is developed for extracting the 2-dimensional strain tensor from the SAD patterns. Using this technique, atomic-level principal strains from micrometre-sized regions of freestanding amorphous Ti{sub 0.45}Al{sub 0.55} thin films were measured during in-situ TEM tensile deformation. The thin films were deformed using MEMS based testing stages that allow simultaneous measurement of the macroscopic stress and strain. The calculated atomic-level principal strains show a linear dependence on the applied stress, and good correspondence with the measured macroscopic strains. The calculated Poisson’s ratio of 0.23 is reasonable for brittle metallic glasses. The technique yields a strain accuracy of about 1×10{sup −4} and shows the potential to obtain localized strain profiles/maps of amorphous thin film samples. - Highlights: • A TEM method to measure elastic strain in metallic glass films is proposed. • Method is based on tracking geometric changes in TEM diffraction patterns. • An automatic procedure is developed for extracting the local strain tensor. • Atomic-level strain in amorphous TiAl film was analysed during in-situ deformation. • Capability of the method to obtain micrometer scale strain profiles/maps is shown.

  7. Analytical stiffness matrices with Green-Lagrange strain measure

    DEFF Research Database (Denmark)

    Pedersen, Pauli

    2005-01-01

    Separating the dependence on material and stress/strain state from the dependence on initial geometry, we obtain analytical secant and tangent stiffness matrices. For the case of a linear displacement triangle with uniform thickness and uniform constitutive behaviour closed-form results are listed...... a solution based on Green-Lagrange strain measure. The approach is especially useful in design optimization, because analytical sensitivity analysis then can be performed. The case of a three node triangular ring element for axisymmetric analysis involves small modifications and extension to four node...

  8. Application of a fiber optic grating strain sensor for the measurement of strain under irradiation environment

    International Nuclear Information System (INIS)

    Kaji, Yoshiyuki; Matsui, Yoshinori; Kita, Satoshi; Ide, Hiroshi; Tsukada, Takashi; Tsuji, Hirokazu

    2002-01-01

    In the Japan Atomic Energy Research Institute (JAERI), in-pile strain measurement techniques have been developed using the Japan Materials Testing Reactor (JMTR). In order to evaluate the performance of fiber optic grating sensors under irradiation environment, heat-up and performance tests at elevated temperatures before irradiation and in-pile tests were performed in JMTR. It was determined that it is possible to measure strain under irradiation environment below 1x10 23 n m -2 (E>1 MeV) by a fiber optic grating sensor, because in-pile temperature characteristics were in good agreement with out-of-pile test results

  9. Measurement of probability distributions for internal stresses in dislocated crystals

    Energy Technology Data Exchange (ETDEWEB)

    Wilkinson, Angus J.; Tarleton, Edmund; Vilalta-Clemente, Arantxa; Collins, David M. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Jiang, Jun; Britton, T. Benjamin [Department of Materials, Imperial College London, Royal School of Mines, Exhibition Road, London SW7 2AZ (United Kingdom)

    2014-11-03

    Here, we analyse residual stress distributions obtained from various crystal systems using high resolution electron backscatter diffraction (EBSD) measurements. Histograms showing stress probability distributions exhibit tails extending to very high stress levels. We demonstrate that these extreme stress values are consistent with the functional form that should be expected for dislocated crystals. Analysis initially developed by Groma and co-workers for X-ray line profile analysis and based on the so-called “restricted second moment of the probability distribution” can be used to estimate the total dislocation density. The generality of the results are illustrated by application to three quite different systems, namely, face centred cubic Cu deformed in uniaxial tension, a body centred cubic steel deformed to larger strain by cold rolling, and hexagonal InAlN layers grown on misfitting sapphire and silicon carbide substrates.

  10. Photonic Crystal Fiber Sensors for Strain and Temperature Measurement

    Directory of Open Access Journals (Sweden)

    Jian Ju

    2009-01-01

    Full Text Available This paper discusses the applications of photonic crystal fibers (PCFs for strain and temperature measurement. Long-period grating sensors and in-fiber modal interferometric sensors are described and compared with their conventional single-mode counterparts. The strain sensitivities of the air-silica PCF sensors are comparable or higher than those implemented in conventional single-mode fibers but the temperature sensitivities of the PCF sensors are much lower.

  11. Modeling of stress-strain diagram on the basis of magnetic measurements

    International Nuclear Information System (INIS)

    Gorkunov, Eh.S.; Fedotov, V.P.; Bukhvalov, A.B.; Veselov, I.N.

    1997-01-01

    The model of a stress-strain diagram with taking into account the strain hardening and the growth of metal damageing is proposed. The model is applied to calculate a stress-strain curve for continuous cast 45 steel using the results of magnetic properties measuring. The latter permits predicting the durability of construction elements with the use of nondestructive magnetic testing

  12. Measurement of strains at high temperatures by means of electro-optics holography

    Science.gov (United States)

    Sciammarella, Cesar A.; Bhat, G.; Vaitekunas, Jeffrey

    Electro-optics holographic-moire interferometry is used to measure strains at temperatures up to 1000 C. A description of the instrumentation developed to carry out the measurements is given. The data processing technique is also explained. Main problems encountered in recording patterns at high temperatures are analyzed and possible solutions are outlined. Optical results are compared with strain gage values obtained with instrumented specimens and with theoretical results. Very good agreement is found between optical, strain gage and theoretical results.

  13. A novel compliance measurement in radial arteries using strain-gauge plethysmography

    International Nuclear Information System (INIS)

    Liu, Shing-Hong; Tyan, Chu-Chang; Chang, Kang-Ming

    2009-01-01

    We propose a novel method for assessing the compliance of the radial artery by using a two-axis mechanism and a standard positioning procedure for detecting the optimal measuring site. A modified sensor was designed to simultaneously measure the arterial diameter change waveform (ADCW) and pressure pulse waveform with a strain gauge and piezoresistor. In the x-axis scanning, the sensor could be placed close to the middle of the radial artery when the ADCW reached the maximum amplitude. In the z-axis scanning, the contact pressure was continuously increased for data measurement. Upon the deformation of the strain gauge following the change in the vascular cross-section, the ADCW was transferred to the change of the vascular radius. The loaded strain compliance of the radial artery (C strain ) can be determined by dividing the dynamic changed radius by the pulse pressure. Twenty-three untreated, mild or moderate hypertensive patients aged 29–85 were compared with 14 normotensive patients aged 25–62. The maximum strain compliance between the two groups was significantly different (p < 0.005). Of the hypertensive patients, 14 were at risk of developing hyperlipidemia. There was a significant difference between this and the normotension group (p < 0.005)

  14. A novel compliance measurement in radial arteries using strain-gauge plethysmography.

    Science.gov (United States)

    Liu, Shing-Hong; Tyan, Chu-Chang; Chang, Kang-Ming

    2009-09-01

    We propose a novel method for assessing the compliance of the radial artery by using a two-axis mechanism and a standard positioning procedure for detecting the optimal measuring site. A modified sensor was designed to simultaneously measure the arterial diameter change waveform (ADCW) and pressure pulse waveform with a strain gauge and piezoresistor. In the x-axis scanning, the sensor could be placed close to the middle of the radial artery when the ADCW reached the maximum amplitude. In the Z-axis scanning, the contact pressure was continuously increased for data measurement. Upon the deformation of the strain gauge following the change in the vascular cross-section, the ADCW was transferred to the change of the vascular radius. The loaded strain compliance of the radial artery (C(strain)) can be determined by dividing the dynamic changed radius by the pulse pressure. Twenty-three untreated, mild or moderate hypertensive patients aged 29-85 were compared with 14 normotensive patients aged 25-62. The maximum strain compliance between the two groups was significantly different (p < 0.005). Of the hypertensive patients, 14 were at risk of developing hyperlipidemia. There was a significant difference between this and the normotension group (p < 0.005).

  15. Passive wireless strain measurement based upon the Villari effect and giant magnetoresistance

    Science.gov (United States)

    Windl, Roman; Bruckner, Florian; Abert, Claas; Huber, Christian; Vogler, Christoph; Huber, Thomas; Oezelt, Harald; Suess, Dieter

    2016-12-01

    A passive wireless radio frequency-identification (RFID) stress/strain sensor is presented. Stress is transformed into a change of magnetic field by utilizing an amorphous metal ribbon. This magnetic field change is measured by a giant magnetoresistance magnetic field sensor and converted into a digital value with a RFID chip for wireless access. Standard metal foil strain gauges have a gauge factor GF from around 2 to 5 and suffer from the disadvantage of a physically connected power supply and measurement equipment. For the presented sensor, a strain range of -10 μm/m to 190 μm/m results in a linear sensor response, a gauge factor of GF ≈ 245, and a detectivity of 4.10 nm/m 1/√{Hz } . The detectivity of the presented sensor is similar to the detectivity of a reference metal foil strain gauge. Due to low power consumption and easy signal analysis, this sensor is well suited for long term strain measurement inside closed spaces. RFID adds features like multiple tag detection, wireless passive operation and a user data storage.

  16. Enhanced Strain Measurement Range of an FBG Sensor Embedded in Seven-Wire Steel Strands.

    Science.gov (United States)

    Kim, Jae-Min; Kim, Chul-Min; Choi, Song-Yi; Lee, Bang Yeon

    2017-07-18

    FBG sensors offer many advantages, such as a lack of sensitivity to electromagnetic waves, small size, high durability, and high sensitivity. However, their maximum strain measurement range is lower than the yield strain range (about 1.0%) of steel strands when embedded in steel strands. This study proposes a new FBG sensing technique in which an FBG sensor is recoated with polyimide and protected by a polyimide tube in an effort to enhance the maximum strain measurement range of FBG sensors embedded in strands. The validation test results showed that the proposed FBG sensing technique has a maximum strain measurement range of 1.73% on average, which is 1.73 times higher than the yield strain of the strands. It was confirmed that recoating the FBG sensor with polyimide and protecting the FBG sensor using a polyimide tube could effectively enhance the maximum strain measurement range of FBG sensors embedded in strands.

  17. Characterization of oriented cracks with differential strain analysis

    International Nuclear Information System (INIS)

    Siegfried, R.; Simmons, G.

    1978-01-01

    Linear strain of a rock sample as a function of hydrostatic pressure can be measured with a precision of 2 x 10 -6 . Such high-precision data for three orthogonal directions allow calculation of the distribution function for the porosity due to cracks closing completely at a given pressure. Such data for at least six independent directions yield the zero-pressure strain tensor due to cracks closing completely at a given pressure. The principal values and axes of this tensor distribution function provide information about the orientation of cracks as a function of closure pressure. In this manuscript we first develop the mathematical basis for the technique and then illustrate it with differential strain data for two samples, the Westerly (Rhode Island) granite and the Twin Sisters (Washington) dunite. Strain tensor calculations reveal that each of these samples has a different type of anisotropic crack distribution

  18. Strain sensing systems tailored for tensile measurement of fragile wires

    Science.gov (United States)

    Nyilas, Arman

    2005-12-01

    Fundamental stress versus strain measurements were completed on superconducting Nb3Sn wires within the framework of IEC/TC90 and VAMAS/TWA16. A key task was the assessment of sensing systems regarding resolution, accuracy, and precision when measuring Young's modulus. Prior to actual Nb3Sn wire measurements metallic wires, consisting of copper and stainless steel having diameters similar to the Nb3Sn wire, were extensively investigated with respect to their elastic line properties using different types of extensometers. After these calibration tests Nb3Sn wire measurements of different companies resulted in several important facts with respect to total size and weight of the used extensometers. The size could be correlated to the initial stage of stress versus strain behaviour. In fact, the effect of wire curls resulting from the production line had a profound effect on Young's modulus measurements. Within this context, the possibility of determining Young's modulus from unloading compliance lines in the plastic regime of the stress-strain curve was considered. The data obtained using this test methodology were discussed under consideration of the composite nature of Nb3Sn wire. In addition, a non-contacting sensing system based on a double-beam laser extensometer was used to investigate the potential of this new sensing system.

  19. Strain sensing systems tailored for tensile measurement of fragile wires

    International Nuclear Information System (INIS)

    Nyilas, Arman

    2005-01-01

    Fundamental stress versus strain measurements were completed on superconducting Nb 3 Sn wires within the framework of IEC/TC90 and VAMAS/TWA16. A key task was the assessment of sensing systems regarding resolution, accuracy, and precision when measuring Young's modulus. Prior to actual Nb 3 Sn wire measurements metallic wires, consisting of copper and stainless steel having diameters similar to the Nb 3 Sn wire, were extensively investigated with respect to their elastic line properties using different types of extensometers. After these calibration tests Nb 3 Sn wire measurements of different companies resulted in several important facts with respect to total size and weight of the used extensometers. The size could be correlated to the initial stage of stress versus strain behaviour. In fact, the effect of wire curls resulting from the production line had a profound effect on Young's modulus measurements. Within this context, the possibility of determining Young's modulus from unloading compliance lines in the plastic regime of the stress-strain curve was considered. The data obtained using this test methodology were discussed under consideration of the composite nature of Nb 3 Sn wire. In addition, a non-contacting sensing system based on a double-beam laser extensometer was used to investigate the potential of this new sensing system

  20. Interpretation of strain measurements on nuclear pressure vessels

    International Nuclear Information System (INIS)

    Andersen, S.I.; Engbaek, P.

    1979-11-01

    Selected results from strain measurements on 4 nuclear pressure vessels are presented and discussed. The measurements were made in several different regions of the vessels: transition zones in vessel heads, flanges and bottom parts, nozzels, internal vessel structure and flange bolts. The results presented are based on data obtained by approximately 700 strain-gauges, and a comprehensive knowledge of the quality obtained by such measurements is established. It is shown that a thorough control procedure before and after the test as well as detailed knowledge of the behaviour of the signal from the individual gauges during the test is necessary. If this is omitted, it can be extremely difficult to distinguish between the real structural behaviour and a malfunctioning of a specific gauge installation. In general, most of the measuring results exhibit a very linear behaviour with a negligible zeroshift. However, deviations from linear behaviour are observed in several cases. This nonlinearity can be explained by friction (flange connections) or by gaps (concentrical nozzles) in certain regions, whereas local plastic deformations during the first pressure loadings of the vessel seem to be the reason in other regions. (author)

  1. Measurement test on creep strain rate of uranium-zirconium solid solutions

    International Nuclear Information System (INIS)

    Ogata, Takanari; Akabori, Mitsuo; Ogawa, Toru

    1996-11-01

    In order to measure creep strain rate of a small specimen of U-Zr solid solution, authors proposed an estimation method which was based upon the stress relaxation after compression. It was applied to measurement test on creep strain rate of the U-10wt%Zr specimen in the temperature range of 757 to 911degC. It may be concluded that the proposed method is valid, provided that the strain is within the appropriate range and that sufficient amount of the load decrement is observed. The obtained creep rate of U-10wt%Zr alloy indicated significantly smaller value, compared to the experimental data for pure U metal and evaluated data for U-Pu-Zr alloy. However, more careful measurement is desired in future since the present data are thought to be influenced by the precipitations included in the specimen. (author)

  2. X-Ray-Scattering Measurements Of Strain In PEEK

    Science.gov (United States)

    Cebe, Peggy; Lowry, Lynn E.; Chung, Shirley Y.; Yavrouian, Andre H.; Gupta, Amitava

    1988-01-01

    Internal stress relieved by heating above glass-transition temperature. Report describes wide-angle x-ray scattering and differential scanning calorimetry of specimens of poly(etheretherketone) having undergone various thermal treatments. Wide-angle x-ray scattering particularly useful in determining distances between atoms, crystallinity, and related microstructurally generated phenomena, as thermal expansion and strain. Calorimetric measurements aid interpretation of scattering measurements by enabling correlation with thermal effects.

  3. Influence of Palatal Coverage and Implant Distribution on Implant Strain in Maxillary Implant Overdentures.

    Science.gov (United States)

    Takahashi, Toshihito; Gonda, Tomoya; Mizuno, Yoko; Fujinami, Yozo; Maeda, Yoshinobu

    2016-01-01

    Maxillary implant overdentures are often used in clinical practice. However, there is no agreement or established guidelines regarding prosthetic design or optimal implant placement configuration. The purpose of this study was to examine the influence of palatal coverage and implant number and distribution in relation to impact strain under maxillary implant overdentures. A maxillary edentulous model with implants and experimental overdentures with and without palatal coverage was fabricated. Four strain gauges were attached to each implant, and they were positioned in the anterior, premolar, and molar areas. A vertical occlusal load of 98 N was applied through a mandibular complete denture, and the implant strains were compared using one-way analysis of variance (P = .05). The palatolabial strain was much higher on anterior implants than on other implants in both denture types. Although there was no significant difference between the strain under dentures with and without palatal coverage, palateless dentures tended to result in higher implant strain than dentures with palatal coverage. Dentures supported by only two implants registered higher strain than those supported by four or six implants. Implants under palateless dentures registered higher strain than those under dentures with palatal coverage. Anterior implants exhibited higher palatolabial strain than other implants regardless of palatal coverage and implant configuration; it is therefore recommended that maxillary implant overdentures should be supported by six implants with support extending to the distal end of the arch.

  4. Measuring techniques for autogenous strain of cement paste

    DEFF Research Database (Denmark)

    Lura, Pietro; Jensen, Ole Mejlhede

    2006-01-01

    of the volumetric method. Water absorption is driven by a lowering of the water activity in the cement paste due to dissolved salts in the pore fluid and to self-desiccation. From the moment of casting, significant water uptake was registered in all experiments. This water uptake influenced the volumetric...... measurements by the same order of magnitude as the autogenous strain itself. By performing the measurements in a paraffin oil bath instead of a water bath, this artefact was eliminated. Furthermore, volumetric measurements performed in paraffin oil gave almost identical results as linear measurements performed...

  5. Strain distribution and band structure of InAs/GaAs quantum ring superlattice

    Science.gov (United States)

    Mughnetsyan, Vram; Kirakosyan, Albert

    2017-12-01

    The elastic strain distribution and the band structure of InAs/GaAs one-layer quantum ring superlattice with square symmetry has been considered in this work. The Green's function formalism based on the method of inclusions has been implied to calculate the components of the strain tensor, while the combination of Green's function method with the Fourier transformation to momentum space in Pikus-Bir Hamiltonian has been used for obtaining the miniband energy dispersion surfaces via the exact diagonalization procedure. The dependencies of the strain tensor components on spatial coordinates are compared with ones for single quantum ring and are in good agreement with previously obtained results for cylindrical quantum disks. It is shown that strain significantly affects the miniband structure of the superlattice and has contribution to the degeneracy lifting effect due to heavy hole-light hole coupling. The demonstrated method is simple and provides reasonable results for comparatively small Hamiltonian matrix. The obtained results may be useful for further investigation and construction of novel devices based on quantum ring superlattices.

  6. Novel method for measuring a dense 3D strain map of robotic flapping wings

    Science.gov (United States)

    Li, Beiwen; Zhang, Song

    2018-04-01

    Measuring dense 3D strain maps of the inextensible membranous flapping wings of robots is of vital importance to the field of bio-inspired engineering. Conventional high-speed 3D videography methods typically reconstruct the wing geometries through measuring sparse points with fiducial markers, and thus cannot obtain the full-field mechanics of the wings in detail. In this research, we propose a novel system to measure a dense strain map of inextensible membranous flapping wings by developing a superfast 3D imaging system and a computational framework for strain analysis. Specifically, first we developed a 5000 Hz 3D imaging system based on the digital fringe projection technique using the defocused binary patterns to precisely measure the dynamic 3D geometries of rapidly flapping wings. Then, we developed a geometry-based algorithm to perform point tracking on the precisely measured 3D surface data. Finally, we developed a dense strain computational method using the Kirchhoff-Love shell theory. Experiments demonstrate that our method can effectively perform point tracking and measure a highly dense strain map of the wings without many fiducial markers.

  7. Apparatus Producing an Even Distribution of Strain into Carries

    Science.gov (United States)

    Hrabovský, Leopold

    2017-10-01

    In many high-rise residential buildings or multi-storey warehouses, machinery, so called lifts, is used for the vertical transportation of people or weights between two or more altitudinally distant places. Carriers used for lifts are steel ropes or sprocket chains, on which a cage or a counterbalance is hinged. Apparatus of all carriers, attached to the hinge of the cage or counterbalance, should be even. This can be made only by hammer hinge. Fixed or springe hinge cannot be a perfect equalizing apparatus. This article describes an apparatus, which allows an even distribution of the strain into lift carriers, which use springe hinge of carrier ropes.

  8. Draft Genome Sequence of Two Sphingopyxis sp. Strains, Dominant Members of the Bacterial Community Associated with a Drinking Water Distribution System Simulator

    Science.gov (United States)

    We report the draft genome of two Sphingopyxis spp. strains isolated from a chloraminated drinking water distribution system simulator. Both strains are ubiquitous residents and early colonizers of water distribution systems. Genomic annotation identified a class 1 integron (in...

  9. Estimation of piping temperature fluctuations based on external strain measurements

    International Nuclear Information System (INIS)

    Morilhat, P.; Maye, J.P.

    1993-01-01

    Due to the difficulty to carry out measurements at the inner sides of nuclear reactor piping subjected to thermal transients, temperature and stress variations in the pipe walls are estimated by means of external thermocouples and strain-gauges. This inverse problem is solved by spectral analysis. Since the wall harmonic transfer function (response to a harmonic load) is known, the inner side signal will be obtained by convolution of the inverse transfer function of the system and of the strain measurement enables detection of internal temperature fluctuations in a frequency range beyond the scope of the thermocouples. (authors). 5 figs., 3 refs

  10. Measuring heavy-tailedness of distributions

    Science.gov (United States)

    Jordanova, Pavlina K.; Petkova, Monika P.

    2017-12-01

    Different questions related with analysis of extreme values and outliers arise frequently in practice. To exclude extremal observations and outliers is not a good decision, because they contain important information about the observed distribution. The difficulties with their usage are usually related with the estimation of the tail index in case it exists. There are many measures for the center of the distribution, e.g. mean, mode, median. There are many measures for the variance, asymmetry and kurtosis, but there is no easy characteristic for heavy-tailedness of the observed distribution. Here we propose such a measure, give some examples and explore some of its properties. This allows us to introduce classification of the distributions, with respect to their heavy-tailedness. The idea is to help and navigate practitioners for accurate and easier work in the field of probability distributions. Using the properties of the defined characteristics some distribution sensitive extremal index estimators are proposed and their properties are partially investigated.

  11. Strain measurement in and analysis for hydraulic test of CPR1000 reactor pressure vessel

    International Nuclear Information System (INIS)

    Zhou Dan; Zhuang Dongzhen

    2013-01-01

    The strain measurement in hydraulic test of CPR1000 reactor pressure vessel performed in Dongfang Heavy Machinery Co., Ltd. is introduced. The detail test scheme and method was introduced and the measurement results of strain and stress was given. Meanwhile the finite element analysis was performed for the pressure vessel, which was generally matched with the measurement results. The reliability of strain measurement was verified and the high strength margin of vessel was shown, which would give a good reference value for the follow-up hydraulic tests and strength analysis of reactor pressure vessel. (authors)

  12. Development of a fiber optic pavement subgrade strain measurement system

    Science.gov (United States)

    Miller, Craig Emerson

    2000-11-01

    This dissertation describes the development of a fiber optic sensing system to measure strains within the soil subgrade of highway pavements resulting from traffic loads. The motivation to develop such a device include improvements to: (1)all phases of pavement design, (2)theoretical models used to predict pavement performance, and (3)pavement rehabilitation. The design of the sensing system encompasses selecting an appropriate transducer design as well as the development of optimal optical and demodulation systems. The first is spring based, which attempts to match its spring stiffness to that of the soil-data indicate it is not an optimal transducer design. The second transducer implements anchoring plates attached to two telescoping tubes which allows the soil to be compacted to a desired density between the plates to dictate the transducer's behavior. Both transducers include an extrinsic Fabry- Perot cavity to impose the soil strains onto a phase change of the optical signal propagating through the cavity. The optical system includes a low coherence source and allows phase modulation via path length stretching by adding a second interferometer in series with the transducer, resulting in a path matched differential interferometer. A digitally implemented synthetic heterodyne demodulator based on a four step phase stepping algorithm is used to obtain unambiguous soil strain information from the displacement of the Fabry-Perot cavity. The demodulator is calibrated and characterized by illuminating the transducer with a second long coherence source of different wavelength. The transducer using anchoring plates is embedded within cylindrical soil specimens of varying soil types and soil moisture contents. Loads are applied to the specimen and resulting strains are measured using the embedded fiber optic gage and LVDTs attached to the surface of the specimen. This experimental verification is substantiated using a finite element analysis to predict any differences

  13. The measurement of the modal strain fields using digital shearography

    Directory of Open Access Journals (Sweden)

    Gomes J.M.

    2010-06-01

    Full Text Available This work presents a Michelson shearography interferometer configuration associated with stroboscopic double illumination technique for the measurement of modal rotation fields and their strain fields on a clamped circular aluminium plate. The speckle pattern is frozen by the synchronization between the LASER illumination and the modal vibration of the object. The quantitative evaluation is performed for each digital shearogram using a time modulation technique. The setup of double illumination LASER with out-of-plane opposite sensitivity allows the two phase maps measurement of the modal spatial gradient. The modal rotation and strain fields are extracted by the combination of this two digital phase maps. Image processing techniques are applied on the phase maps to obtain full-field measurements using a dedicated post-processing algorithm. Finally, is presented a comparison between the experimental measurement and the numerical solution.

  14. The influence of texture on the strain measured by diffraction

    International Nuclear Information System (INIS)

    Penning, P.; Brakman, C.M.

    1988-01-01

    Strain, as determined by diffraction techniques, is calculated from its constituents. First, the fraction of the crystals that have the proper orientation for diffraction. One degree of freedom is present: the angle of rotation φ 2 '' about the scattering vector that the diffracting crystals have in common. The proper orientations, expressed in Euler angles, lie on a line ('trace') in orientation space. The density along the trace is asserted to be known as a Fourier series in φ 2 ''. Second, the strain in the diffracting crystals. The simplest possible models are discussed: the Voigt and Reuss approximations. The symmetries of the crystal (m3 or m3m) and of the orientation distribution function (o.d.f.) are taken into account. The dilatation in spacing of the reflecting planes is found as a Fourier series in φ 2 '' also. Only the zeroth, first and second harmonic (including phase angles: five parameters) play a part. The diffraction strain is the average over the angle φ 2 '' of the dilatation, weighted with the product of the orientation density and the square of the structure factor. For each contributing trace, the corresponding Fourier coefficients have to be multiplied and added to obtain the diffraction strain. The symmetry of the diffraction pole figure is derived. (orig.)

  15. Strain study of gold nanomaterials as HR-TEM calibration standard.

    Science.gov (United States)

    Peng, X Y; Zhou, L Q; Li, X; Tao, X F; Ren, L L; Cao, W H; Xu, G F

    2015-12-01

    This work presents the use of high resolution electron microscopy (HREM) and geometric phase analysis (GPA) to measure the interplanar spacing and strain distribution of three gold nanomaterials, respectively. The results showed that the {111} strain was smaller than the {002} strain for any kind of gold materials at the condition of same measuring method. The 0.65% of {111} strain in gold film measured by HREM (0.26% measured by GPA) was smaller than the {111} strains in two gold particles. The presence of lattice strain was interpreted according to the growth mechanism of metallic thin film. It is deduced that the {111} interplanar spacing of the gold thin film is suitable for high magnification calibration of transmission electron microscopy (TEM) and the gold film is potential to be a new calibration standard of TEM. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Bluetooth-based distributed measurement system

    International Nuclear Information System (INIS)

    Tang Baoping; Chen Zhuo; Wei Yuguo; Qin Xiaofeng

    2007-01-01

    A novel distributed wireless measurement system, which is consisted of a base station, wireless intelligent sensors and relay nodes etc, is established by combining of Bluetooth-based wireless transmission, virtual instrument, intelligent sensor, and network. The intelligent sensors mounted on the equipments to be measured acquire various parameters and the Bluetooth relay nodes get the acquired data modulated and sent to the base station, where data analysis and processing are done so that the operational condition of the equipment can be evaluated. The establishment of the distributed measurement system is discussed with a measurement flow chart for the distributed measurement system based on Bluetooth technology, and the advantages and disadvantages of the system are analyzed at the end of the paper and the measurement system has successfully been used in Daqing oilfield, China for measurement of parameters, such as temperature, flow rate and oil pressure at an electromotor-pump unit

  17. Bluetooth-based distributed measurement system

    Science.gov (United States)

    Tang, Baoping; Chen, Zhuo; Wei, Yuguo; Qin, Xiaofeng

    2007-07-01

    A novel distributed wireless measurement system, which is consisted of a base station, wireless intelligent sensors and relay nodes etc, is established by combining of Bluetooth-based wireless transmission, virtual instrument, intelligent sensor, and network. The intelligent sensors mounted on the equipments to be measured acquire various parameters and the Bluetooth relay nodes get the acquired data modulated and sent to the base station, where data analysis and processing are done so that the operational condition of the equipment can be evaluated. The establishment of the distributed measurement system is discussed with a measurement flow chart for the distributed measurement system based on Bluetooth technology, and the advantages and disadvantages of the system are analyzed at the end of the paper and the measurement system has successfully been used in Daqing oilfield, China for measurement of parameters, such as temperature, flow rate and oil pressure at an electromotor-pump unit.

  18. Bluetooth-based distributed measurement system

    Energy Technology Data Exchange (ETDEWEB)

    Tang Baoping; Chen Zhuo; Wei Yuguo; Qin Xiaofeng [Department of Mechatronics, College of Mechanical Engineering, Chongqing University, Chongqing, 400030 (China)

    2007-07-15

    A novel distributed wireless measurement system, which is consisted of a base station, wireless intelligent sensors and relay nodes etc, is established by combining of Bluetooth-based wireless transmission, virtual instrument, intelligent sensor, and network. The intelligent sensors mounted on the equipments to be measured acquire various parameters and the Bluetooth relay nodes get the acquired data modulated and sent to the base station, where data analysis and processing are done so that the operational condition of the equipment can be evaluated. The establishment of the distributed measurement system is discussed with a measurement flow chart for the distributed measurement system based on Bluetooth technology, and the advantages and disadvantages of the system are analyzed at the end of the paper and the measurement system has successfully been used in Daqing oilfield, China for measurement of parameters, such as temperature, flow rate and oil pressure at an electromotor-pump unit.

  19. Pipeline Bending Strain Measurement and Compensation Technology Based on Wavelet Neural Network

    Directory of Open Access Journals (Sweden)

    Rui Li

    2016-01-01

    Full Text Available The bending strain of long distance oil and gas pipelines may lead to instability of the pipeline and failure of materials, which seriously deteriorates the transportation security of oil and gas. To locate the position of the bending strain for maintenance, an Inertial Measurement Unit (IMU is usually adopted in a Pipeline Inspection Gauge (PIG. The attitude data of the IMU is usually acquired to calculate the bending strain in the pipe. However, because of the vibrations in the pipeline and other system noises, the resulting bending strain calculations may be incorrect. To improve the measurement precision, a method, based on wavelet neural network, was proposed. To test the proposed method experimentally, a PIG with the proposed method is used to detect a straight pipeline. It can be obtained that the proposed method has a better repeatability and convergence than the original method. Furthermore, the new method is more accurate than the original method and the accuracy of bending strain is raised by about 23% compared to original method. This paper provides a novel method for precisely inspecting bending strain of long distance oil and gas pipelines and lays a foundation for improving the precision of inspection of bending strain of long distance oil and gas pipelines.

  20. Measurements and predictions of strain pole figures for uniaxially compressed stainless steel

    International Nuclear Information System (INIS)

    Larsson, C.; Clausen, B.; Holden, T.M.; Bourke, M.A.M.

    2004-01-01

    Strain pole figures representative of residual intergranular strains were determined from an -2.98% uniaxially compressed austenitic stainless steel sample. The measurements were made using neutron diffraction on the recently commissioned Spectrometer for Materials Research at Temperature and Stress (SMARTS) at Los Alamos National Laboratory, USA. The measurements were compared with predictions from an elasto-plastic self-consistent model and found to be in good agreement

  1. Measurements and predictions of strain pole figures for uniaxially compressed stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, C. [Division of Engineering Materials, Department of Mechanical Engineering, Linkoeping University, 58183 Linkoeping (Sweden)]. E-mail: clarsson@cfl.rr.com; Clausen, B. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Holden, T.M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Bourke, M.A.M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2004-09-15

    Strain pole figures representative of residual intergranular strains were determined from an -2.98% uniaxially compressed austenitic stainless steel sample. The measurements were made using neutron diffraction on the recently commissioned Spectrometer for Materials Research at Temperature and Stress (SMARTS) at Los Alamos National Laboratory, USA. The measurements were compared with predictions from an elasto-plastic self-consistent model and found to be in good agreement.

  2. Dislocation, crystallite size distribution and lattice strain of magnesium oxide nanoparticles

    Science.gov (United States)

    Sutapa, I. W.; Wahid Wahab, Abdul; Taba, P.; Nafie, N. L.

    2018-03-01

    The oxide of magnesium nanoparticles synthesized using sol-gel method and analysis of the structural properties was conducted. The functional groups of nanoparticles has been analysed by Fourier Transform Infrared Spectroscopy (FT-IR). Dislocations, average size of crystal, strain, stress, the energy density of crystal, crystallite size distribution and morphologies of the crystals were determined based on X-ray diffraction profile analysis. The morphological of the crystal was analysed based on the image resulted from SEM analysis. The crystallite size distribution was calculated with the contention that the particle size has a normal logarithmic form. The most orientations of crystal were determined based on the textural crystal from diffraction data of X-ray diffraction profile analysis. FT-IR results showed the stretching vibration mode of the Mg-O-Mg in the range of 400.11-525 cm-1 as a broad band. The average size crystal of nanoparticles resulted is 9.21 mm with dislocation value of crystal is 0.012 nm-2. The strains, stress, the energy density of crystal are 1.5 x 10-4 37.31 MPa; 0.72 MPa respectively. The highest texture coefficient value of the crystal is 0.98. This result is supported by morphological analysis using SEM which shows most of the regular cubic-shaped crystals. The synthesis method is suitable for simple and cost-effective synthesis model of MgO nanoparticles.

  3. Thermal Aging Effects on Residual Stress and Residual Strain Distribution on Heat Affected Zone of Alloy 600 in Dissimilar Metal Weld

    Energy Technology Data Exchange (ETDEWEB)

    Ham, Junhyuk; Choi, Kyoung Joon; Kim, Ji Hyun [UNIST, Ulsan (Korea, Republic of)

    2016-10-15

    Dissimilar metal weld (DMW), consisting of Alloy 600, Alloy 182, and A508 Gr.3, has been widely used as a joining material of the reactor pressure vessel penetration nozzle and the steam generator tubing for pressurized water reactors (PWR) because of its good mechanical strength, thermal conductivity, and corrosion resistance. Residual tensile stress is mainly nominated as a cause of SCC in light water reactors by IAEA report. So, to relax the residual stress, post-weld heat treatment is required after manufacturing process such as welding. However, thermal treatment has a great effect on the microstructure and the chromium depletion profile on Alloy 600, so called sensitization. By this reason, HAZ on Alloy 600 is critical to crack. According to G.A. Young et al., Crack growth rates (CGR) in the Alloy 600 HAZ were about 30 times faster than those in the Alloy 600 base metal tested under the same conditions. And according to Z.P. Lu et al., CGR in the Alloy 600 HAZ can be more than 20 times higher than that in its base metal. There are some methods to measure the exact value of residual stress on the material surface. The most common way is X-ray diffraction method (XRD). The principle of XRD is based on lattice strains and depends on the changes in the spacing of the atomic planes in material. And there is a computer simulation method to estimate residual stress distribution which is called ANSYS. This study was conducted to investigate how thermal aging affects residual stress and residual strain distribution of Alloy 600 HAZ. Following conclusions can be drawn from this study. According to preceding researches and this study, both the relaxation of residual stress and the change of residual strain follow as similar way, spreading out from concentrated region. The result of Vickers micro-hardness tester shows that tensile residual stresses are distributed broadly on the material aged by 15 years. Therefore, HT400{sub Y}15 material is weakest state for PWSCC. The

  4. The role of silicon, vacancies, and strain in carbon distribution in low temperature bainite

    Energy Technology Data Exchange (ETDEWEB)

    Sampath, S. [Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-Universität Bochum, Bochum 44780 (Germany); Rementeria, R. [Department of Physical Metallurgy, National Center for Metallurgical Research (CENIM-CSIC), Avda. Gregorio del Amo, 8, Madrid E-28040 (Spain); Huang, X. [Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-Universität Bochum, Bochum 44780 (Germany); Poplawsky, J.D. [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, 1 Bethel Valley Road, P.O. Box 2008, MS-6064, Oak Ridge, TN 37831 (United States); Garcia-Mateo, C.; Caballero, F.G. [Department of Physical Metallurgy, National Center for Metallurgical Research (CENIM-CSIC), Avda. Gregorio del Amo, 8, Madrid E-28040 (Spain); Janisch, R., E-mail: rebecca.janisch@rub.de [Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-Universität Bochum, Bochum 44780 (Germany)

    2016-07-15

    We investigated the phenomenon of carbon supersaturation and carbon clustering in bainitic ferrite with atom probe tomography (APT) and ab-initio density functional theory (DFT) calculations. The experimental results show a homogeneous distribution of silicon in the microstructure, which contains both ferrite and retained austenite. This distribution is mimicked well by the computational approach. In addition, an accumulation of C in certain regions of the bainitic ferrite with C concentrations up to 13 at % is observed. Based on the DFT results, these clusters are explained as strained, tetragonal regions in the ferritic bainite, in which the solution enthalpy of C can reach large, negative values. It seems that Si itself only has a minor influence on this phenomenon. - Highlights: • Atom-probe tomography shows supersaturation of bainitic ferrite with C. • Ab initio calculations show that Si has negative influence on C solubility. • Combination of tetragonality of the lattice and strain can explain C accumulation.

  5. Application of fiber optic grating strain sensor for measurement of strain under irradiation environment

    International Nuclear Information System (INIS)

    Kaji, Y.; Matsui, Y.; Kita, S.; Ide, H.; Tsukada, T.; Tsuji, H.

    2001-01-01

    In Japan Atomic Energy Research Institute (JAERI), in-pile strain measurement techniques have been developed using Japan Materials Testing Reactor (JMTR). In order to evaluate the performance of fiber optic grating sensor under irradiation environment, heat-up and performance tests at elevated temperature before irradiation and in-pile tests were performed in JMTR. (author)

  6. NDE (Nondestructive examination) by ultrasonic, photo-elastic, strain measuring and FEM (Finite Element Method)

    International Nuclear Information System (INIS)

    Gu Fangyu; Zeng Xiao

    1990-01-01

    It is considered impossible to inspect flaw by using ordinary mechanical measuring methods. In this paper, it is found that the stree and strain distortions of pressure vessel with 2D linear shape crack in the deep location appear the 'cat effect' on the surface of stracture, and that the location and size of the crack can be determined with strain measuring and FEM according to 'cat effect' of strain distortion

  7. Molecular markers for tracking the origin and worldwide distribution of invasive strains of Puccinia striiformis

    DEFF Research Database (Denmark)

    Walter, Stephanie; Ali, Sajid; Kemen, Eric

    2016-01-01

    .g., the spreading of two aggressive and high temperature adapted strains to three continents since 2000. The combination of sequence-characterized amplified region (SCAR) markers, which were developed from two specific AFLP fragments, differentiated the two invasive strains, PstS1 and PstS2 from all other P....... striiformis strains investigated at a worldwide level. The application of the SCAR markers on 566 isolates showed that PstS1 was present in East Africa in the early 1980s and then detected in the Americas in 2000 and in Australia in 2002. PstS2 which evolved from PstS1 became widespread in the Middle East...... as the most plausible origin of the two invasive strains. The SCAR markers developed in the present study provide a rapid, inexpensive, and efficient tool to track the distribution of P. striiformis invasive strains, PstS1 and PstS2....

  8. Strain distribution in freestanding Si/Si{sub x}N{sub y} membranes studied by transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Hongye, E-mail: hongye18@mm.kyushu-u.ac.j [Faculty of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Ikeda, Ken-ichi; Hata, Satoshi; Nakashima, Hideharu [Faculty of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Wang, Dong; Nakashima, Hiroshi [Art, Science and Technology Center for Cooperative Research, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan)

    2010-09-30

    Strain was induced in a bridge-shaped freestanding Si membrane (FSSM) by depositing an amorphous Si{sub x}N{sub y} layer to surround the Si membrane. Convergent beam electron diffraction revealed that compressive strain is distributed uniformly along the horizontal direction in Si{sub x}N{sub y}-deposited FSSM. On the other hand, strain decreases to almost zero at the ends of the FSSM, where the Si{sub x}N{sub y} layer beneath the Si layer is replaced by a SiO{sub 2} buried oxide layer.

  9. Direct Strain and Slope and Slope Measurement Using 2D DSPSI

    International Nuclear Information System (INIS)

    Dandach, W.; Molimard, J.; Picart, P.

    2011-01-01

    Large variety of optical full-field measurement techniques are being developed and applied to solve mechanical problems. Since each technique possesses its own merits, it is important to know the capabilities and limitations of such techniques. Among these optical full-field methods, interferometry techniques take an important place. They are based on illumination with coherent light (laser). In shearing interferometry the difference of the out of-plane displacement in two neighboring object points is directly measured. Since object displacement does not result in interferometry fringes, the method is suited for localization of strain concentrations and is indeed used in industry for this purpose. DSPSI possesses the advantage over conventional out-of-plane displacement-sensitive interferometry, that only a single difference of the unwrapped phase map is required to obtain flexural strains, thereby relieving problems with noise and reduction in the field of view. A first work in this domain (DSPSI) [1] was made in 1973, later recent studies emerged to provide a quantitative system of measurements [2]. This work aims to present the results of strain and slope measurements using digital speckle pattern shearing interferometry (DSPSI). (author)

  10. Variation of Shrinkage Strain within the Depth of Concrete Beams

    Directory of Open Access Journals (Sweden)

    Jong-Hyun Jeong

    2015-11-01

    Full Text Available The variation of shrinkage strain within beam depth was examined through four series of time-dependent laboratory experiments on unreinforced concrete beam specimens. Two types of beam specimens, horizontally cast and vertically cast, were tested; shrinkage variation was observed in the horizontally cast specimens. This indicated that the shrinkage variation within the beam depth was due to water bleeding and tamping during the placement of the fresh concrete. Shrinkage strains were measured within the beam depth by two types of strain gages, surface-attached and embedded. The shrinkage strain distribution within the beam depth showed a consistent tendency for the two types of gages. The test beams were cut into four sections after completion of the test, and the cutting planes were divided into four equal sub-areas to measure the aggregate concentration for each sub-area of the cutting plane. The aggregate concentration increased towards the bottom of the beam. The shrinkage strain distribution was estimated by Hobbs’ equation, which accounts for the change of aggregate volume concentration.

  11. Development of a strain measurement method for non-plane specimens by means of computer picture processing

    International Nuclear Information System (INIS)

    Yoshioka, Akira; Soneda, Naoki; Yagawa, Genki; Miyoshi, Akio.

    1988-01-01

    Integrity Tests of the Fast Breeder Reactor components are often conducted at an elevated temperature, say 550deg C. Since high-temperature strain measurement using special strain gauges is costly and unappropriate for large and repeated strains, the authors have developed an optical strain measurement method and system based on computer picture processing and the triangulation principle. The present method enables us to measure the strain in specimen with curved surfaces. Its operation is also easy, because of the automatic distinction of marks from noises. The verification tests with a plate specimen and a cylindrical one are performed under elevated temperatures. The results show that the present method is very suitable to the tests under elevated temperatures and that the measurement error of strain is within 0.2 % (2000μ), which is reasonable considering the limitation of hardware. (author)

  12. Measuring techniques for autogenous strain of cement paste

    DEFF Research Database (Denmark)

    Lura, Pietro; Jensen, Ole Mejlhede

    2007-01-01

    Volumetric measurement of autogenous strain is frequently performed by placing the fresh cement paste in a rubber membrane submerged in water. The volume change of the cement paste is measured by the amount of water displaced by the submerged sample. Volumetric and linear measurements of autogenous...... of the volumetric method. Water absorption is driven by a lowering of the water activity in the cement paste due to dissolved salts in the pore fluid and to self-desiccation. From the moment of casting, significant water uptake was registered in all experiments. This water uptake influenced the volumetric...... on the same cement pastes....

  13. Stress and strain distribution in three different mini dental implant designs using in implant retained overdenture: a finite element analysis study

    Science.gov (United States)

    AUNMEUNGTONG, W.; KHONGKHUNTHIAN, P.; RUNGSIYAKULL, P.

    2016-01-01

    SUMMARY Finite Element Analysis (FEA) has been used for prediction of stress and strain between dental implant components and bone in the implant design process. Purpose Purpose of this study was to characterize and analyze stress and strain distribution occurring in bone and implants and to compare stress and strain of three different implant designs. Materials and methods Three different mini dental implant designs were included in this study: 1. a mini dental implant with an internal implant-abutment connection (MDIi); 2. a mini dental implant with an external implant-abutment connection (MDIe); 3. a single piece mini dental implant (MDIs). All implant designs were scanned using micro-CT scans. The imaging details of the implants were used to simulate models for FEA. An artificial bone volume of 9×9 mm in size was constructed and each implant was placed separately at the center of each bone model. All bone-implant models were simulatively loaded under an axial compressive force of 100 N and a 45-degree force of 100 N loading at the top of the implants using computer software to evaluate stress and strain distribution. Results There was no difference in stress or strain between the three implant designs. The stress and strain occurring in all three mini dental implant designs were mainly localized at the cortical bone around the bone-implant interface. Oblique 45° loading caused increased deformation, magnitude and distribution of stress and strain in all implant models. Conclusions Within the limits of this study, the average stress and strain in bone and implant models with MDIi were similar to those with MDIe and MDIs. The oblique 45° load played an important role in dramatically increased average stress and strain in all bone-implant models. Clinical implications Mini dental implants with external or internal connections have similar stress distribution to single piece mini dental implants. In clinical situations, the three types of mini dental implant

  14. Stress and strain distribution in three different mini dental implant designs using in implant retained overdenture: a finite element analysis study.

    Science.gov (United States)

    Aunmeungtong, W; Khongkhunthian, P; Rungsiyakull, P

    2016-01-01

    Finite Element Analysis (FEA) has been used for prediction of stress and strain between dental implant components and bone in the implant design process. Purpose of this study was to characterize and analyze stress and strain distribution occurring in bone and implants and to compare stress and strain of three different implant designs. Three different mini dental implant designs were included in this study: 1. a mini dental implant with an internal implant-abutment connection (MDIi); 2. a mini dental implant with an external implant-abutment connection (MDIe); 3. a single piece mini dental implant (MDIs). All implant designs were scanned using micro-CT scans. The imaging details of the implants were used to simulate models for FEA. An artificial bone volume of 9×9 mm in size was constructed and each implant was placed separately at the center of each bone model. All bone-implant models were simulatively loaded under an axial compressive force of 100 N and a 45-degree force of 100 N loading at the top of the implants using computer software to evaluate stress and strain distribution. There was no difference in stress or strain between the three implant designs. The stress and strain occurring in all three mini dental implant designs were mainly localized at the cortical bone around the bone-implant interface. Oblique 45° loading caused increased deformation, magnitude and distribution of stress and strain in all implant models. Within the limits of this study, the average stress and strain in bone and implant models with MDIi were similar to those with MDIe and MDIs. The oblique 45° load played an important role in dramatically increased average stress and strain in all bone-implant models. Mini dental implants with external or internal connections have similar stress distribution to single piece mini dental implants. In clinical situations, the three types of mini dental implant should exhibit the same behavior to chewing force.

  15. Internal electric-field-lines distribution in CdZnTe detectors measured using X-ray mapping

    International Nuclear Information System (INIS)

    Bolotnikov, A.E.; Camarda, G.S.; Cui, Y.; Hossain, A.; Yang, G.; Yao, H.W.; James, R.B.

    2009-01-01

    The ideal operation of CdZnTe devices entails having a uniformly distributed internal electric field. Such uniformity especially is critical for thick long-drift-length detectors, such as large-volume CPG and 3-D multi-pixel devices. Using a high-spatial resolution X-ray mapping technique, we investigated the distribution of the electric field in real devices. Our measurements demonstrate that in thin detectors, 1 cm, with a large aspect ratio (thickness-to-width ratio), we observed two effects: the electric field lines bending away from or towards the side surfaces, which we called, respectively, the focusing field-line distribution and the defocusing field-line distribution. In addition to these large-scale variations, the field-line distributions were locally perturbed by the presence of extended defects and residual strains existing inside the crystals. We present our data clearly demonstrating the non-uniformity of the internal electric field

  16. From measurements errors to a new strain gauge design for composite materials

    DEFF Research Database (Denmark)

    Mikkelsen, Lars Pilgaard; Salviato, Marco; Gili, Jacopo

    2015-01-01

    Significant over-prediction of the material stiffness in the order of 1-10% for polymer based composites has been experimentally observed and numerical determined when using strain gauges for strain measurements instead of non-contact methods such as digital image correlation or less stiff method...

  17. Comprehensive comparison of macro-strain mode and displacement mode based on different sensing technologies

    Science.gov (United States)

    Hong, Wan; Zhang, Jian; Wu, Gang; Wu, Zhishen

    2015-01-01

    A comprehensive comparison of macro-strain mode and displacement mode obtained from distributed macro-strain sensing and high-density point sensing (such as accelerometers) technologies is presented in this paper. Theoretical derivation reveals that displacement mode shape from accelerometers and modal macro-strain from distributed macro-strain sensors can be converted into each other. However, it is realized that displacement mode shape as global behavior of a structure can still be calculated with high-precision from modal macro-strain considering measurement errors in practical monitoring, whereas modal macro-strain can hardly be accurately achieved from displacement mode shape when signals are corrupted with noise in practical monitoring. Simulation and experiment results show that the calculated displacement mode shapes are very close to the actual ones even if the noise level reaches 5%. Meanwhile, damage index using measured modal macro-strain is still effective when the measurements are corrupted with 5% noise which is reliable for damage detection in practical monitoring. Calculating modal macro-strain from noise-polluted displacement mode shape will cause an unacceptable error if the noise level reaches only 0.5%, which has been verified in the simulation.

  18. Stress and strain measurements in solids

    International Nuclear Information System (INIS)

    Askegaard, V.

    1978-01-01

    A design basis is given for stress- and strain cells to be used in a solid either externally loaded or with a stressfree strain field (for example shrinkage). A stress- and a strain cell has been designed for use in granular materials. Calibration tests show either good or reasonably good correspondance with calculated values. (orig.) [de

  19. Temperature and strain measurements in concrete using micro-structure optical fiber sensors

    Energy Technology Data Exchange (ETDEWEB)

    Areias, Lou [EURIDICE/SCK - CEN, Mol (Belgium); Vrije Univ. Brussels (Belgium); Geernaert, Thomas; Sulejmani, Sanne [Vrije Univ. Brussels (Belgium); and others

    2015-07-01

    A recent test carried out to evaluate the construction feasibility of the Belgian supercontainer concept incorporated several types of state-of-the-art sensors and innovative monitoring techniques, including the use of different types of optical fiber sensors. One of these is a relatively new type of sensor developed by the Brussels Photonics Team (B-PHOT) of the Vrije Universiteit Brussel. The sensor uses highly birefringent microstructured optical fibers equipped with fiber Bragg gratings (MOFBGs) sensors. They were embedded in a carbon-fiber reinforced composite plate to provide protection against the concrete's highly alkaline environment, facilitate installation in the concrete mould and allow the transfer of strain onto the fiber. The double reflection spectrum of the MOFBGs allows monitoring strain and temperature simultaneously. This paper presents results of temperature and strain measurements obtained with MOFBG sensors during a {sup 1}/{sub 2}-scale test performed in 2013. The results compare well with similar measurements obtained using conventional thermocouples and vibrating wire strain gauges.

  20. Fast recovery strain measurements in a nuclear test environment

    International Nuclear Information System (INIS)

    Kitchen, W.R.; Nauman, W.J.; Vollmer, D.W.

    1979-01-01

    The recovery of early-time (50 μs or less) strain gage data on structural response experiments in underground nuclear tests has been a continuing problem for experimenters at the Nevada Test Site. Strain measurement is one of the primary techniques used to obtain experimental data for model verification and correlation with predicted effects. Peak strains generally occur within 50 to 100 μs of the radiation exposure. Associated with the exposure is an intense electromagnetic impulse that produces potentials of kilovolts and currents of kiloamperes on the experimental structures. For successful operation, the transducer and associated recording system must recover from the initial noise overload and accurately track the strain response within about 50 μs of the nuclear detonation. A gaging and fielding technique and a recording system design that together accomplish these objectives are described. Areas discussed include: (1) noise source model; (2) experimental cassette design, gage application, grounding, and shielding; (3) cable design and shielding between gage and recorder; (4) recorder design including signal conditioner/amplifier, digital encoder, buffer memory, and uphole data transmission; and (5) samples of experimental data

  1. Distribution, persistence and interchange of Epstein-Barr virus strains among PBMC, plasma and saliva of primary infection subjects.

    Science.gov (United States)

    Kwok, Hin; Chan, Koon Wing; Chan, Kwok Hung; Chiang, Alan Kwok Shing

    2015-01-01

    Our study aimed at investigating the distribution, persistence and interchange of viral strains among peripheral blood mononuclear cells (PBMC), plasma and saliva of primary Epstein-Barr virus (EBV) infection subjects. Twelve infectious mononucleosis (IM) patients and eight asymptomatic individuals (AS) with primary EBV infection were followed longitudinally at several time points for one year from the time of diagnosis, when blood and saliva samples were collected and separated into PBMC, plasma and saliva, representing circulating B cell, plasma and epithelial cell compartments, respectively. To survey the viral strains, genotyping assays for the natural polymorphisms in two latent EBV genes, EBNA2 and LMP1, were performed and consisted of real-time PCR on EBNA2 to distinguish type 1 and 2 viruses, fluorescent-based 30-bp typing assay on LMP1 to distinguish deletion and wild type LMP1, and fluorescent-based heteroduplex tracking assays on both EBNA2 and LMP1 to distinguish defined polymorphic variants. No discernible differences were observed between IM patients and AS. Multiple viral strains were acquired early at the start of infection. Stable persistence of dominant EBV strains in the same tissue compartment was observed throughout the longitudinal samples. LMP1-defined strains, China 1, China 2 and Mediterranean+, were the most common strains observed. EBNA2-defined groups 1 and 3e predominated the PBMC and saliva compartments. Concordance of EBNA2 and LMP1 strains between PBMC and saliva suggested ready interchange of viruses between circulating B cell and epithelial cell pools, whilst discordance of viral strains observed between plasma and PBMC/saliva indicated presence of viral pools in other undetermined tissue compartments. Taken together, the results indicated that the distribution, persistence and interchange of viral strains among the tissue compartments are more complex than those proposed by the current model of EBV life cycle.

  2. Strain measurements during pressurized thermal shock experiment

    International Nuclear Information System (INIS)

    Tarso Vida Gomes, P. de; Julio Ricardo Barreto Cruz; Tanius Rodrigues Mansur; Denis Henrique Bianchi Scaldaferri; Miguel Mattar Neto

    2005-01-01

    For the life extension of nuclear power plants, the residual life of most of their components must be evaluated along all their operating time. Concerning the reactor pressure vessel, the pressurized thermal shock (PTS) is a very important event to be considered. For better understanding the effects of this kind of event, tests are made. The approach described here consisted of building a simplified in-scale physical model of the reactor pressure vessel, submitting it to the actual operating temperature and pressure conditions and provoking a thermal shock by means of cold water flow in its external surface. To conduct such test, the Nuclear Technology Development Center (CDTN) has been conducting several studies related to PTS and has also built a laboratory that has made possible the simulation of the PTS loading conditions. Several cracks were produced in the external surface of the reactor pressure vessel model. Strain gages were fixed by means of electrical discharge welding over the cracks regions in both external and internal surfaces. The temperature was monitored in 10 points across the vessel wall. The internal pressure was manually controlled and monitored using a pressure transducer. Two PTS experiments were conducted and this paper presents the strain measurement procedures applied to the reactor pressure vessel model, during the PTS, using strain gages experimental methodology. (authors)

  3. Evaluation of resilient abutment components on measured strain using dynamic loading conditions.

    Science.gov (United States)

    Morton, D; Stanford, C M; Aquilino, S A

    1998-07-01

    Factors that affect transmission of strain from prostheses to bone may affect the long-term success of loaded implants. Current in vitro models are theoretically predictive (finite element modeling) or facsimile (photoelastic) in nature. A more clinically relevant in vitro model for strain evaluation should be investigated. This study attempted: (1) to validate a human cadaver bone model for vitro measurement of cortical bone strain, and (2) to evaluate the effect on cortical strain measurements of a resilient plastic component incorporated within a titanium implant in response to variable dynamic loading. Two IMZ (Interpore International) abutment alternatives were used: the titanium Abutment Complete and the polyoxymethylene Intra-mobile Element. The model system consisted of two implants placed in unfixed human cadaver ulna bone to simulate an implant bound edentulous region. Four biaxial rosette strain gauges simultaneously recorded cortical bone strain immediately mesial and distal to each implant. During experimentation a simulated prosthetic framework supported by either titanium or polyoxymethylene abutments was dynamically loaded 6 min from the terminal abutment along a cantilever extension. Cyclic nominal peak loads were applied with a materials testing machine at 20-N intervals from 20 to 200 N at a crosshead speed of 5 mm/minute. The protocol allowed frequency of load application to vary. A Newtonian linear correlation (r2 > or = 0.98) between load application and strain output was determined for each gauge position except for the terminal gauge located opposite the cantilever. Cortical strains recorded were within reported physiologic ranges involved in bone modeling and remodeling. Further, the polyoxymethylene abutment components did not result in reduction of peak microstrain at any gauge position. The Intra-mobile Element abutments, however, did increase the time required to complete 10 loading cycles when compared with the titanium Abutment

  4. Internal strain measurement using pulsed neutron diffraction at LANSCE

    International Nuclear Information System (INIS)

    Goldstone, J.A.; Bourke, M.A.M.; Shi, N.

    1994-01-01

    The presence of residual stress in engineering components can effect their mechanical properties and structural integrity. Neutron diffraction in the only technique that can make nondestructive measurements in the interior of components. By recording the change in crystalline lattice spacings, elastic strains can be measured for individual lattice reflections. Using a pulsed neutron source, all lattice reflections are recorded in each measurement, which allows for easy examination of heterogeneous materials such as metal matrix composites. Measurements made at the Manuel Lujan Jr. Neutron Scattering Center (LANSCE) demonstrate the potential at pulsed sources for in-situ stress measurements at ambient and elevated temperatures

  5. Up-taper-based Mach-Zehnder interferometer for temperature and strain simultaneous measurement.

    Science.gov (United States)

    Kang, Zexin; Wen, Xiaodong; Li, Chao; Sun, Jiang; Wang, Jing; Jian, Shuisheng

    2014-04-20

    A novel all-fiber sensing configuration for simultaneous measurements of temperature and strain based on the up-taper Mach-Zehnder interferometer (MZI) with an in-line embedded fiber Bragg grating (FBG) is proposed and experimentally demonstrated. This configuration consists of two up-tapers fabricated by an excessive fusion splicing method and a short segment of inscribed FBG. Due to the different responses of the up-taper MZI and the FBG to the uniform variation of temperature and strain, the simultaneous measurement for these two variables could be achieved by real-time monitoring the transmission spectrum. For 0.01 nm wavelength resolution, a resolution of 0.311°C in temperature can be achieved, and the average strain resolution is 10.07 με.

  6. Measurement of stress strain and vibrational properties of tendons

    Science.gov (United States)

    Revel, Gian Marco; Scalise, Alessandro; Scalise, Lorenzo

    2003-08-01

    The authors present a new non-intrusive experimental procedure based on laser techniques for the measurement of mechanical properties of tendons. The procedure is based on the measurement of the first resonance frequency of the tendon by laser Doppler vibrometry during in vitro tensile experiments, with the final aim of establishing a measurement procedure to perform the mechanical characterization of tendons by extracting parameters such as the resonance frequency, also achievable during in vivo investigation. The experimental procedure is reported, taking into account the need to simulate the physiological conditions of the Achilles tendon, and the measurement technique used for the non-invasive determination of tendon cross-sectional area during tensile vibration tests at different load levels is described. The test procedure is based on a tensile machine, which measures longitudinal tendons undergoing controlled load conditions. Cross-sectional area is measured using a new non-contact procedure for the measurement of tendon perimeter (repeatability of 99% and accuracy of 2%). For each loading condition, vibration resonance frequency and damping, cross-sectional area and tensile force are measured, allowing thus a mechanical characterization of the tendon. Tendon stress-strain curves are reported. Stress-strain curves have been correlated to the first vibration resonance frequency and damping of the tendon measured using a single-point laser Doppler vibrometer. Moreover, experimental results have been compared with a theoretical model of a vibrating cord showing discrepancies. In vitro tests are reported, demonstrating the validity of the method for the comparison of different aged rabbit tendons.

  7. Printed strain sensors for early damage detection in engineering structures

    Science.gov (United States)

    Zymelka, Daniel; Yamashita, Takahiro; Takamatsu, Seiichi; Itoh, Toshihiro; Kobayashi, Takeshi

    2018-05-01

    In this paper, we demonstrate the analysis of strain measurements recorded using a screen-printed sensors array bonded to a metal plate and subjected to high strains. The analysis was intended to evaluate the capabilities of the printed strain sensors to detect abnormal strain distribution before actual defects (cracks) in the analyzed structures appear. The results demonstrate that the developed device can accurately localize the enhanced strains at the very early stage of crack formation. The promising performance and low fabrication cost confirm the potential suitability of the printed strain sensors for applications within the framework of structural health monitoring (SHM).

  8. Design and Testing of the Strain Transducer for Measuring Deformations of Pipelines Operating in the Mining-deformable Ground Environment

    Directory of Open Access Journals (Sweden)

    Gawedzki Waclaw

    2015-10-01

    Full Text Available Design and laboratory test results of the strain transducer intended for monitoring and assessing stress states of pipelines sited in mining areas are presented in this paper. This transducer allows measuring strains of pipelines subjected to external forces - being the mining operations effect. Pipeline strains can have a direct influence on a tightness loss and penetration of the transported fluid into the environment. The original strain gauge transducer was proposed for performing measurements of strains. It allows measuring circumferential strains and determining the value and direction of the main longitudinal strain. This strain is determined on the basis of measuring component longitudinal strains originating from axial forces and the resultant bending moment. The main purpose of investigations was the experimental verification of the possibility of applying the strain transducer for measuring strains of polyethylene pipelines. The obtained results of the transducer subjected to influences of tensile and compression forces are presented and tests of relaxation properties of polyethylene are performed.

  9. Bragg-edge neutron transmission strain tomography for in situ loadings

    Energy Technology Data Exchange (ETDEWEB)

    Wensrich, C.M., E-mail: christopher.wensrich@newcastle.edu.au [School of Engineering, The University of Newcastle, Callaghan, NSW 2308 (Australia); Hendriks, J.N.; Gregg, A. [School of Engineering, The University of Newcastle, Callaghan, NSW 2308 (Australia); Meylan, M.H. [School of Mathematical and Physical Sciences, The University of Newcastle, Callaghan, NSW 2308 (Australia); Luzin, V. [Bragg Institute, Australian Nuclear Science and Technology Organisation (ANSTO), Kirrawee, NSW 2232 (Australia); Tremsin, A.S. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

    2016-09-15

    An approach for tomographic reconstruction of three-dimensional strain distributions from Bragg-edge neutron transmission strain images is outlined and investigated. This algorithm is based on the link between Bragg-edge strain measurements and the Longitudinal Ray Transform, which has been shown to be sensitive only to boundary displacement. By exploiting this observation we provide a method for reconstructing boundary displacement from sets of Bragg-edge strain images. In the case where these displacements are strictly the result of externally applied tractions, corresponding internal strain fields can then be found through traditional linear-static finite element methods. This approach is tested on synthetic data in two-dimensions, where the rate of convergence in the presence of measurement noise and beam attenuation is examined.

  10. Soft tissue strain measurement using an optical method

    Science.gov (United States)

    Toh, Siew Lok; Tay, Cho Jui; Goh, Cho Hong James

    2008-11-01

    Digital image correlation (DIC) is a non-contact optical technique that allows the full-field estimation of strains on a surface under an applied deformation. In this project, the application of an optimized DIC technique is applied, which can achieve efficiency and accuracy in the measurement of two-dimensional deformation fields in soft tissue. This technique relies on matching the random patterns recorded in images to directly obtain surface displacements and to get displacement gradients from which the strain field can be determined. Digital image correlation is a well developed technique that has numerous and varied engineering applications, including the application in soft and hard tissue biomechanics. Chicken drumstick ligaments were harvested and used during the experiments. The surface of the ligament was speckled with black paint to allow for correlation to be done. Results show that the stress-strain curve exhibits a bi-linear behavior i.e. a "toe region" and a "linear elastic region". The Young's modulus obtained for the toe region is about 92 MPa and the modulus for the linear elastic region is about 230 MPa. The results are within the values for mammalian anterior cruciate ligaments of 150-300 MPa.

  11. Strain Measurements of Chondrules and Refraction Inclusion in Allende

    Science.gov (United States)

    Tait, Alastair W.; Fisher, Kent R.; Simon, Justin I.

    2013-01-01

    This study uses traditional strain measurement techniques, combined with X-ray computerized tomography (CT), to evaluate petrographic evidence in the Allende CV3 chondrite for preferred orientation and to measure strain in three dimensions. The existence of petrofabrics and lineations was first observed in carbonaceous meteorites in the 1960's. Yet, fifty years later only a few studies have reported that meteorites record such features. Impacts are often cited as the mechanism for this feature, although plastic deformation from overburden and nebular imbrication have also been proposed. Previous work conducted on the Leoville CV3 and the Parnallee LL3 chondrites, exhibited a minimum uniaxial shortening of 33% and 21%, respectively. Petrofabrics in Allende CV3 have been looked at before; previous workers using Electron Back Scatter Diffraction (EBSD) found a major-axis alignment of olivine inside dark inclusions and an "augen"-like preferred orientation of olivine grains around more competent chondrules

  12. Dependence of Strain Distribution on In Content in InGaN/GaN Quantum Wires and Spherical Quantum Dots

    Science.gov (United States)

    Sharma, Akant Sagar; Dhar, S.

    2018-02-01

    The distribution of strain, developed in zero-dimensional quantum spherical dots and one-dimensional cylindrical quantum wires of an InGaN/GaN system is calculated as functions of radius of the structure and indium mole fraction. The strain shows strong dependence on indium mole fraction at small distances from the center. The strain associated with both the structures is found to decrease exponentially with the increase in dot or cylinder radius and increases linearly with indium content.

  13. Measuring strain and rotation fields at the dislocation core in graphene

    Science.gov (United States)

    Bonilla, L. L.; Carpio, A.; Gong, C.; Warner, J. H.

    2015-10-01

    Strain fields, dislocations, and defects may be used to control electronic properties of graphene. By using advanced imaging techniques with high-resolution transmission electron microscopes, we have measured the strain and rotation fields about dislocations in monolayer graphene with single-atom sensitivity. These fields differ qualitatively from those given by conventional linear elasticity. However, atom positions calculated from two-dimensional (2D) discrete elasticity and three-dimensional discrete periodized Föppl-von Kármán equations (dpFvKEs) yield fields close to experiments when determined by geometric phase analysis. 2D theories produce symmetric fields whereas those from experiments exhibit asymmetries. Numerical solutions of dpFvKEs provide strain and rotation fields of dislocation dipoles and pairs that also exhibit asymmetries and, compared with experiments, may yield information on out-of-plane displacements of atoms. While discrete theories need to be solved numerically, analytical formulas for strains and rotation about dislocations can be obtained from 2D Mindlin's hyperstress theory. These formulas are very useful for fitting experimental data and provide a template to ascertain the importance of nonlinear and nonplanar effects. Measuring the parameters of this theory, we find two characteristic lengths between three and four times the lattice spacings that control dilatation and rotation about a dislocation. At larger distances from the dislocation core, the elastic fields decay to those of conventional elasticity. Our results may be relevant for strain engineering in graphene and other 2D materials of current interest.

  14. Neutron-diffraction measurement of the evolution of strain for non-uniform plastic deformation

    CERN Document Server

    Rogge, R B; Boyce, D

    2002-01-01

    Neutrons are particularly adept for the validation of modeling predictions of stress and strain. In recent years, there has been a significant effort to model the evolution of both the macroscopic stresses and the intergranular stress during plastic deformation. These have had broad implications with regard to understanding the evolution of residual stress and to diffraction-based measurements of strain. Generally the modeling and associated measurements have been performed for simple uniaxial tension, leaving questions with regard to plastic deformation under multi-axial stress and non-uniform stress. Extensive measurements of the strain profile across a plastic hinge for each of a series of loading and unloading cycles to progressively higher degrees of plastic deformation are presented. These measurements are used to assess multiple-length-scale finite-element modeling (FEM) of the plastic hinge, in which the elements will range in size from single crystallites (as used in successful simulations of uniaxia...

  15. Neutron-diffraction measurement of the evolution of strain for non-uniform plastic deformation

    International Nuclear Information System (INIS)

    Rogge, R.B.; Dawson, P.R.; Boyce, D.

    2002-01-01

    Neutrons are particularly adept for the validation of modeling predictions of stress and strain. In recent years, there has been a significant effort to model the evolution of both the macroscopic stresses and the intergranular stress during plastic deformation. These have had broad implications with regard to understanding the evolution of residual stress and to diffraction-based measurements of strain. Generally the modeling and associated measurements have been performed for simple uniaxial tension, leaving questions with regard to plastic deformation under multi-axial stress and non-uniform stress. Extensive measurements of the strain profile across a plastic hinge for each of a series of loading and unloading cycles to progressively higher degrees of plastic deformation are presented. These measurements are used to assess multiple-length-scale finite-element modeling (FEM) of the plastic hinge, in which the elements will range in size from single crystallites (as used in successful simulations of uniaxial tension) to macroscopic elements (as typically used in FEM simulations). (orig.)

  16. Assessment of strain and strain rate by two-dimensional speckle tracking in mice: comparison with tissue Doppler echocardiography and conductance catheter measurements.

    Science.gov (United States)

    Ferferieva, V; Van den Bergh, A; Claus, P; Jasaityte, R; La Gerche, A; Rademakers, F; Herijgers, P; D'hooge, J

    2013-08-01

    This study was designed in order to compare the strain and strain rate deformation parameters assessed by speckle tracking imaging (STI) with those of tissue Doppler imaging (TDI) and conductance catheter measurements in chronic murine models of left ventricular (LV) dysfunction. Twenty-four male C57BL/6J mice were assigned to wild-type (n = 8), myocardial infarction (n = 8) and transaortic constriction (n = 8) groups. Echocardiographic and conductance measurements were simultaneously performed at rest and during dobutamine infusion (5 µg/kg/min) in all animals 10 weeks post-surgery. The LV circumferential strain (Scirc) and the strain rate (SRcirc) were derived from grey scale and tissue Doppler data at frame rates of 224 and 375 Hz, respectively. Scirc and SRcirc by TDI/STI correlated well with the preload recruitable stroke work (PRSW) (r = -0.64 and -0.71 for TDI; r = -0.46 and -0.50 for STI, P < 0.05). Both modalities showed a good agreement with respect to Scirc and SRcirc (r = 0.60 and r = 0.63, P < 0.05). During stress, however, TDI-estimated Scirc and SRcirc values were predominantly higher than those measured by STI (P < 0.05). The similarity of Scirc and SRcirc measurements with respect to the STI/TDI data was examined by the Bland-Altman analysis. In mice, the STI- and TDI-derived strain and strain rate deformation parameters relate closely to intrinsic myocardial function. At low heart rate-to-frame rate ratios (HR/FR), both STI and TDI are equally acceptable for assessing the LV function non-invasively in these animals. At HR/FR (e.g. dobutamine challenge), however, these methods cannot be used interchangeably as STI underestimates S and SR at high values.

  17. A Research on Low Modulus Distributed Fiber Optical Sensor for Pavement Material Strain Monitoring.

    Science.gov (United States)

    Meng, Lingjian; Wang, Linbing; Hou, Yue; Yan, Guannan

    2017-10-19

    The accumulated irreversible deformation in pavement under repeated vehicle loadings will cause fatigue failure of asphalt concrete. It is necessary to monitor the mechanical response of pavement under load by using sensors. Previous studies have limitations in modulus accommodation between the sensor and asphalt pavement, and it is difficult to achieve the distributed monitoring goal. To solve these problems, a new type of low modulus distributed optical fiber sensor (DOFS) for asphalt pavement strain monitoring is fabricated. Laboratory experiments have proved the applicability and accuracy of the newly-designed sensor. This paper presents the results of the development.

  18. Measurement of strain and strain relaxation in free-standing Si membranes by convergent beam electron diffraction and finite element method

    International Nuclear Information System (INIS)

    Gao, H.; Ikeda, K.; Hata, S.; Nakashima, H.; Wang, D.; Nakashima, H.

    2011-01-01

    Bridge-shaped free-standing Si membranes (FSSM), strained by low-pressure (LP) Si x N y , plasma-enhanced (PE) Si x N y and Si x Ge 1-x stressors, were measured by convergent beam electron diffraction (CBED) and the finite element method (FEM). The results of CBED show that, while the strain along the length of the FSSM is compressive in an LPSi x N y /Si sample, those along the length of the FSSM are tensile in PESi x N y /Si and Si x Ge 1-x /Si samples. The average absolute values of strains are different in FSSM with LPSi x N y , PESi x N y and Si x Ge 1-x as stressors. The FEM was used to compensate the results of CBED taking into account the strain relaxation in transmission electron microscopy (TEM) sample preparation. The FEM results give the strain properties in three dimensions, and are in good agreement with the results of CBED. There is approximately no strain relaxation along the length of FSSM, and the elastic strains along the other two axes in FSSM are partially relaxed by thinning down for the preparation of TEM samples.

  19. Quantitative size-dependent structure and strain determination of CdSe nanoparticles using atomic pair distribution function analysis

    Energy Technology Data Exchange (ETDEWEB)

    Masadeh, A S; Bozin, E S; Farrow, C L; Paglia, G; Juhas, P; Billinge, S J. L.; Karkamkar, A; Kanatzidis, M G [Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-1116 (United States); Department of Chemistry, Michigan State University, East Lansing, Michigan 48824-1116 (United States)

    2007-09-15

    The size-dependent structure of CdSe nanoparticles, with diameters ranging from 2 to 4 nm, has been studied using the atomic pair distribution function (PDF) method. The core structure of the measured CdSe nanoparticles can be described in terms of the wurtzite atomic structure with extensive stacking faults. The density of faults in the nanoparticles is {approx}50%. The diameter of the core region was extracted directly from the PDF data and is in good agreement with the diameter obtained from standard characterization methods, suggesting that there is little surface amorphous region. A compressive strain was measured in the Cd-Se bond length that increases with decreasing particle size being 0.5% with respect to bulk CdSe for the 2 nm diameter particles. This study demonstrates the size-dependent quantitative structural information that can be obtained even from very small nanoparticles using the PDF approach.

  20. Measurement of stress-strain behaviour of human hair fibres using optical techniques.

    Science.gov (United States)

    Lee, J; Kwon, H J

    2013-06-01

    Many studies have presented stress-strain relationship of human hair, but most of them have been based on an engineering stress-strain curve, which is not a true representation of stress-strain behaviour. In this study, a more accurate 'true' stress-strain curve of human hair was determined by applying optical techniques to the images of the hair deformed under tension. This was achieved by applying digital image cross-correlation (DIC) to 10× magnified images of hair fibres taken under increasing tension to estimate the strain increments. True strain was calculated by summation of the strain increments according to the theoretical definition of 'true' strain. The variation in diameter with the increase in longitudinal elongation was also measured from the 40× magnified images to estimate the Poisson's ratio and true stress. By combining the true strain and the true stress, a true stress-strain curve could be determined, which demonstrated much higher stress values than the conventional engineering stress-strain curve at the same degree of deformation. Four regions were identified in the true stress-strain relationship and empirical constitutive equations were proposed for each region. Theoretical analysis on the necking condition using the constitutive equations provided the insight into the failure mechanism of human hair. This analysis indicated that local thinning caused by necking does not occur in the hair fibres, but, rather, relatively uniform deformation takes place until final failure (fracture) eventually occurs. © 2012 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  1. Design of triaxial test with controlled suction: measure of strain

    International Nuclear Information System (INIS)

    Gasc-Barbier, M.; Cosenza, Ph.; Ghoreychi, M.; Chanchole, S.; Cosenza, Ph.; Tessier, D.

    2000-01-01

    Experimental study of mechanical behavior of clayey materials under hygrometric condition is usually performed either on unloaded samples or by means of classical odometer tests used in soil mechanics. Such methods are not well adapted to hard deep clayey rocks with little deformability, porosity and permeability. Moreover, stress and strain tensors having a significant effect on hygro-mechanical behaviour and properties cannot be measured and investigated appropriately by classical tests. This is why a specific triaxial test was designed in which the sample is surrounded by a fiber glass tissue allowing air circulation and then by silicon on which confining pressure is applied. Thus, equilibrium between air and sample was reduced. Stress and strain tensors were also measured in time on the sample subjected to a mechanical loading and to a controlled suction. After presentation of the test, preliminary results are given. (authors)

  2. Determination of strain concentration by microfluorescent densitometry of X-ray topography: a bridge between microfracture and continuum mechanics

    International Nuclear Information System (INIS)

    Kalman, Z.H.; Chaudhuri, J.; Weng, G.J.; Weissmann, S.

    1980-01-01

    The strain distribution in the vicinity of the notches of a double-notched, elastically bent silicon crystal was determined by measuring the diffracted X-ray intensities. The measurements were carried out on traverse-oscillation topographs of a crystal section extending through both notches. Strain distributions were determined by measuring the local densities of silver deposits (measurements of 'opacities') with a scanning electron microscope. It was shown that both the density range and spatial resolution of X-ray densitometry were larger by an order of magnitude than those of optical densitometry. The strain concentration factors associated with the notches were measured experimentally and calculated by continuum mechanics. The results were in satisfactory agreement. Also, the experimentally found rise of strains, to a maximum in the critical area adjacent to the notch root, followed the trend predicted by continuum mechanics. (Auth.)

  3. Surface Crack Detection in Prestressed Concrete Cylinder Pipes Using BOTDA Strain Sensors

    Directory of Open Access Journals (Sweden)

    Zhigang Xu

    2017-01-01

    Full Text Available Structural deterioration after a period of service can induce the failure of prestressed concrete cylinder pipes (PCCPs, with microcracks in the coating leading to the corrosion of the prestressed wires. In this paper, we propose the use of Brillouin optical time-domain analysis (BOTDA strain sensors for detecting the onset of microcracking in PCCP coating: the BOTDA strain sensors are mounted on the surface of the PCCP, and distributed strain measurements are employed to assess the cracks in the mortar coating and the structural state of the pipe. To validate the feasibility of the proposed approach, experimental investigations were conducted on a prototype PCCP segment, wherein the inner pressure was gradually increased to 1.6 MPa. Two types of BOTDA strain sensors—the steel wire packaged fiber optic sensor and the polyelastic packaged fiber optic sensor—were employed in the experiments. The experimental distributed measurements agreed well with the finite element computations, evidencing that the investigated strain sensors are sensitive to localized deterioration behaviors such as PCCP microcracking.

  4. High-resolution spatiotemporal strain mapping reveals non-uniform deformation in micropatterned elastomers

    Science.gov (United States)

    Aksoy, B.; Rehman, A.; Bayraktar, H.; Alaca, B. E.

    2017-04-01

    Micropatterns are generated on a vast selection of polymeric substrates for various applications ranging from stretchable electronics to cellular mechanobiological systems. When these patterned substrates are exposed to external loading, strain field is primarily affected by the presence of microfabricated structures and similarly by fabrication-related defects. The capturing of such nonhomogeneous strain fields is of utmost importance in cases where study of the mechanical behavior with a high spatial resolution is necessary. Image-based non-contact strain measurement techniques are favorable and have recently been extended to scanning tunneling microscope and scanning electron microscope images for the characterization of mechanical properties of metallic materials, e.g. steel and aluminum, at the microscale. A similar real-time analysis of strain heterogeneity in elastomers is yet to be achieved during the entire loading sequence. The available measurement methods for polymeric materials mostly depend on cross-head displacement or precalibrated strain values. Thus, they suffer either from the lack of any real-time analysis, spatiotemporal distribution or high resolution in addition to a combination of these factors. In this work, these challenges are addressed by integrating a tensile stretcher with an inverted optical microscope and developing a subpixel particle tracking algorithm. As a proof of concept, the patterns with a critical dimension of 200 µm are generated on polydimethylsiloxane substrates and strain distribution in the vicinity of the patterns is captured with a high spatiotemporal resolution. In the field of strain measurement, there is always a tradeoff between minimum measurable strain value and spatial resolution. Current noncontact techniques on elastomers can deliver a strain resolution of 0.001% over a minimum length of 5 cm. More importantly, inhomogeneities within this quite large region cannot be captured. The proposed technique can

  5. High-resolution spatiotemporal strain mapping reveals non-uniform deformation in micropatterned elastomers

    International Nuclear Information System (INIS)

    Aksoy, B; Alaca, B E; Rehman, A; Bayraktar, H

    2017-01-01

    Micropatterns are generated on a vast selection of polymeric substrates for various applications ranging from stretchable electronics to cellular mechanobiological systems. When these patterned substrates are exposed to external loading, strain field is primarily affected by the presence of microfabricated structures and similarly by fabrication-related defects. The capturing of such nonhomogeneous strain fields is of utmost importance in cases where study of the mechanical behavior with a high spatial resolution is necessary. Image-based non-contact strain measurement techniques are favorable and have recently been extended to scanning tunneling microscope and scanning electron microscope images for the characterization of mechanical properties of metallic materials, e.g. steel and aluminum, at the microscale. A similar real-time analysis of strain heterogeneity in elastomers is yet to be achieved during the entire loading sequence. The available measurement methods for polymeric materials mostly depend on cross-head displacement or precalibrated strain values. Thus, they suffer either from the lack of any real-time analysis, spatiotemporal distribution or high resolution in addition to a combination of these factors. In this work, these challenges are addressed by integrating a tensile stretcher with an inverted optical microscope and developing a subpixel particle tracking algorithm. As a proof of concept, the patterns with a critical dimension of 200 µ m are generated on polydimethylsiloxane substrates and strain distribution in the vicinity of the patterns is captured with a high spatiotemporal resolution. In the field of strain measurement, there is always a tradeoff between minimum measurable strain value and spatial resolution. Current noncontact techniques on elastomers can deliver a strain resolution of 0.001% over a minimum length of 5 cm. More importantly, inhomogeneities within this quite large region cannot be captured. The proposed technique can

  6. Estimation of strain from piezoelectric effect and domain switching in morphotropic PZT by combined analysis of macroscopic strain measurements and synchrotron X-ray data

    International Nuclear Information System (INIS)

    Kungl, Hans; Theissmann, Ralf; Knapp, Michael; Baehtz, Carsten; Fuess, Hartmut; Wagner, Susanne; Fett, Theo; Hoffmann, Michael J.

    2007-01-01

    Morphotropic PZT ceramics are State of the art materials for ferroelectric actuators. Essential performance parameters for these materials are strain and hysteresis. On a microscopic scale the strain provided by an electric field is due to two different mechanisms. The piezoelectric effect causes an elongation of the unit cells, whereas domain switching changes their crystallographic orientation by aligning the polarization axis towards the field direction. A method is outlined to estimate the contribution of the two mechanisms to total strain by combining macroscopic strain measurements and X-ray diffraction (XRD) data. Results from macroscopic measurements of remanent and unipolar strain with the corresponding data on texture, derived from in situ synchrotron radiation XRD patterns, are analyzed and evaluated by a semi-empirical approach. The method was applied to six morphotropic, LaSr doped PZT materials of different Zr/Ti ratios. Results are discussed with respect to the differences between the materials

  7. Strain measurements in a rotary engine housing

    Science.gov (United States)

    Lee, C. M.; Bond, T. H.; Addy, H. E.; Chun, K. S.; Lu, C. Y.

    1989-01-01

    The development of structural design tools for Rotary Combustion Engines (RCE) using Finite Element Modeling (FEM) requires knowledge about the response of engine materials to various service conditions. This paper describes experimental work that studied housing deformation as a result of thermal, pressure and mechanical loads. The measurement of thermal loads, clamping pressure, and deformation was accomplished by use of high-temperature strain gauges, thermocouples, and a high speed data acquisition system. FEM models for heat transfer stress analysis of the rotor housing will be verified and refined based on these experimental results.

  8. Method for independent strain and temperature measurement in polymeric tensile test specimen using embedded FBG sensors

    DEFF Research Database (Denmark)

    Pereira, Gilmar Ferreira; McGugan, Malcolm; Mikkelsen, Lars Pilgaard

    2016-01-01

    to calculate independently the strain and temperature are presented in the article, together with a measurement resolution study. This multi-parameter measurement method was applied to an epoxy tensile specimen, tested in a unidirectional tensile test machine with a temperature controlled cabinet. A full......A novel method to obtain independent strain and temperature measurements using embedded Fibre Bragg Grating (FBG) in polymeric tensile test specimens is presented in this paper. The FBG strain and temperature cross-sensitivity was decoupled using two single mode FBG sensors, which were embedded...... of temperature, from 40 C to -10 C. The consistency of the expected theoretical results with the calibration procedure and the experimental validation shows that this proposed method is applicable to measure accurate strain and temperature in polymers during static or fatigue tensile testing. Two different...

  9. Notch root strain measurement of WE43-T6 magnesium alloy using electronic speckle pattern interferometry

    International Nuclear Information System (INIS)

    Liew, H.L.; Ahmad, A.; Ramesh, S.; Purbolaksono, J.

    2013-01-01

    Highlights: • The use of ESPI for measuring total strains at the notch root of specimens. • Fine meshing in micron scale at the notch root regions. • The maximum elastic strain is shifted to be further away from the notch root tip. - Abstract: The notch root elasto-plastic strains of circumferentially grooved round specimen of cast magnesium WE43-T6 were experimentally measured using the electronic speckle pattern interferometry (ESPI) and numerically evaluated using the finite element analysis (FEA). The specimens have notch radii of 1.6 mm and 0.8 mm and an opening angle of 60°. The technique of ESPI showed its accuracy in measuring three-dimensional surface deformations on large negatively curved manifolds. The measured nominal stress for rupture is well beyond the ultimate strength, suggesting the existence of significant biaxial stress at the notch root region. The ESPI-based strains on the notch tips were shown to be in agreement with those evaluated by the FEA. The FEA also showed that the maximum elastic strain is shifted away from the notch root surface as the plastic strain is predominant

  10. Localized strain measurements of the intervertebral disc annulus during biaxial tensile testing.

    Science.gov (United States)

    Karakolis, Thomas; Callaghan, Jack P

    2015-01-01

    Both inter-lamellar and intra-lamellar failures of the annulus have been described as potential modes of disc herniation. Attempts to characterize initial lamellar failure of the annulus have involved tensile testing of small tissue samples. The purpose of this study was to evaluate a method of measuring local surface strains through image analysis of a tensile test conducted on an isolated sample of annular tissue in order to enhance future studies of intervertebral disc failure. An annulus tissue sample was biaxial strained to 10%. High-resolution images captured the tissue surface throughout testing. Three test conditions were evaluated: submerged, non-submerged and marker. Surface strains were calculated for the two non-marker conditions based on motion of virtual tracking points. Tracking algorithm parameters (grid resolution and template size) were varied to determine the effect on estimated strains. Accuracy of point tracking was assessed through a comparison of the non-marker conditions to a condition involving markers placed on tissue surface. Grid resolution had a larger effect on local strain than template size. Average local strain error ranged from 3% to 9.25% and 0.1% to 2.0%, for the non-submerged and submerged conditions, respectively. Local strain estimation has a relatively high potential for error. Submerging the tissue provided superior strain estimates.

  11. Straining and wrinkling processes during turbulence-premixed flame interaction measured using temporally-resolved diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Steinberg, Adam M.; Driscoll, James F. [Department of Aerospace Engineering, The University of Michigan, Ann Arbor, MI 48109 (United States)

    2009-12-15

    The dynamical processes of flame surface straining and wrinkling that occur as turbulence interacts with a premixed flame were measured using cinema-stereoscopic PIV (CS-PIV) and orthogonal-plane cinema-stereoscopic PIV (OPCS-PIV). These diagnostics provided temporally resolved measurements of turbulence-flame interaction at frame rates of up to 3 kHz and spatial resolutions as small as 280{mu} m. Previous descriptions of flame straining and wrinkling have typically been derived based on a canonical interaction between a pair of counter-rotating vortices and a planar flame surface. However, it was found that this configuration did not properly represent real turbulence-flame interaction. Interactions resembling the canonical configuration were observed in less than 10% of the recorded frames. Instead, straining and wrinkling were generally caused more geometrically complex turbulence, consisting of large groups of structures that could be multiply curved and intertwined. The effect of the interaction was highly dependent on the interaction geometry. Furthermore, even when the turbulence did exist in the canonical geometry, the straining and wrinkling of the flame surface were not well characterized by the vortical structures. A new mechanistic description of the turbulence-flame interaction was therefore identified and confirmed by the measurements. In this description, flame surface straining is caused by coherent structures of fluid-dynamic strain-rate (strain-rate structures). The role of vortical structures is to curve existing flame surface, creating wrinkles. By simultaneously considering both forms of turbulent structure, turbulence-flame interactions in both the canonical configuration and more complex geometries could be understood. (author)

  12. Study of V-OTDR stability for dynamic strain measurement in piezoelectric vibration

    Science.gov (United States)

    Ren, Meiqi; Lu, Ping; Chen, Liang; Bao, Xiaoyi

    2016-09-01

    In a phase-sensitive optical-time domain reflectometry (Φ-OTDR) system, the challenge for dynamic strain measurement lies in large intensity fluctuations from trace to trace. The intensity fluctuation caused by stochastic characteristics of Rayleigh backscattering sets detection limit for the minimum strength of vibration measurement and causes the large measurement uncertainty. Thus, a trace-to-trace correlation coefficient is introduced to quantify intensity fluctuation of Φ-OTDR traces and stability of the sensor system theoretically and experimentally. A novel approach of measuring dynamic strain induced by various driving voltages of lead zirconate titanate (PZT) in Φ-OTDR is also demonstrated. Piezoelectric vibration signals are evaluated through analyzing peak values of fast Fourier transform spectra at the fundamental frequency and high-order harmonics based on Bessel functions. High trace-to-trace correlation coefficients varying from 0.824 to 0.967 among 100 measurements are obtained in experimental results, showing the good stability of our sensor system, as well as small uncertainty of measured peak values.

  13. Strain measurements of nuclear power plant steam generator antiseismic supports

    International Nuclear Information System (INIS)

    Kulichevsky, R.

    1997-01-01

    The nuclear power plants steam generators have different types of structural supports. One of these types are the antiseismic supports, which are intended to be under stress only if a seismic event takes place. Nevertheless, the antiseismic supports lugs, that are welded to the steam generator vessel, are subjected to thermal fatigue because of the temperature cycles related with the shut down and start up operations performed during the life of the nuclear power plant. In order to evaluate the stresses that the lugs are subjected to, several strain gages were welded on two supports lugs, positioned at two heights of one of the Embalse nuclear power plant steam generators. In this paper, the instrumentation used and the strain measurements obtained during two start up operations are presented. The influence of the plant start up operation parameters on the lugs strain evolution is also analyzed. (author) [es

  14. Measurement of strain and strain relaxation in free-standing Si membranes by convergent beam electron diffraction and finite element method

    Energy Technology Data Exchange (ETDEWEB)

    Gao, H., E-mail: hongye18@mm.kyushu-u.ac.jp [Faculty of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Ikeda, K.; Hata, S.; Nakashima, H. [Faculty of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Wang, D.; Nakashima, H. [Art, Science and Technology Center for Cooperative Research, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan)

    2011-04-15

    Bridge-shaped free-standing Si membranes (FSSM), strained by low-pressure (LP) Si{sub x}N{sub y}, plasma-enhanced (PE) Si{sub x}N{sub y} and Si{sub x}Ge{sub 1-x} stressors, were measured by convergent beam electron diffraction (CBED) and the finite element method (FEM). The results of CBED show that, while the strain along the length of the FSSM is compressive in an LPSi{sub x}N{sub y}/Si sample, those along the length of the FSSM are tensile in PESi{sub x}N{sub y}/Si and Si{sub x}Ge{sub 1-x}/Si samples. The average absolute values of strains are different in FSSM with LPSi{sub x}N{sub y}, PESi{sub x}N{sub y} and Si{sub x}Ge{sub 1-x} as stressors. The FEM was used to compensate the results of CBED taking into account the strain relaxation in transmission electron microscopy (TEM) sample preparation. The FEM results give the strain properties in three dimensions, and are in good agreement with the results of CBED. There is approximately no strain relaxation along the length of FSSM, and the elastic strains along the other two axes in FSSM are partially relaxed by thinning down for the preparation of TEM samples.

  15. Strain measurements using Fiber Bragg Grating sensors in Structural Health Monitoring

    Directory of Open Access Journals (Sweden)

    Daniela ENCIU

    2017-06-01

    Full Text Available The paper presents some results obtained within a project of the “NUCLEU” Program financed by the Ministry of Research and Innovation-ANCS. The project supposes, among others, the design and the realization of a demonstrator for strain and stress measurements made with Fiber Bragg Gratings optical sensors. The paper details the construction of the demonstrator. The strain measurements induced in a cantilevered aluminum plate are compared with the analytical values provided by a mathematical model, and with the numerical values obtained by FEM analysis. The consistency of these comparative data indicates the achievement within the project of a level of competence necessary for later use of FBG sensors in the applicative researches involving the aerospace structures monitoring.

  16. Measurement of internal forces in superconducting accelerator magnets with strain gauge transducers

    International Nuclear Information System (INIS)

    Goodzeit, C.L.; Anerella, M.D.; Ganetis, G.L.

    1988-01-01

    An improved method has been developed for the measurement of internal forces in superconducting accelerator magnets, in particular the compressive stresses in coils and the end restraint forces on the coils. The transducers have been designed to provide improved sensitivity to purely mechanical strain by using bending mode deflections for sensing the applied loads. Strain gauge resistance measurements are made with a new system that eliminates sources of errors due to spurious resistance changes in interconnecting wiring and solder joints. The design of the transducers and their measurement system is presented along with a discussion of the method of compensation for thermal and magnetic effects, methods of calibration with typical calibration data, and measured effect in actual magnets of the thermal stress changes from cooldown and the Lorentz forces during magnet excitation. 13 figs., 1 tab

  17. Strain mapping near a triple junction in strained Ni-based alloy using EBSD and biaxial nanogauges

    Energy Technology Data Exchange (ETDEWEB)

    Clair, A. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France); Foucault, M.; Calonne, O. [Areva ANP, Centre Technique Departement Corrosion-Chimie, 30 Bd de l' industrie, BP 181, 71205 Le Creusot (France); Lacroute, Y.; Markey, L.; Salazar, M.; Vignal, V. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France); Finot, E., E-mail: Eric.Finot@u-bourgogne.fr [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France)

    2011-05-15

    Research highlights: > Surface strains measured using nanogauge were compared to the texture obtained by EBSD. > Statistics of the principal strain discern the grains according to the Schmid factor. > Strain hotspots were localized near a triple junction of alloy 600 under tensile loading. > Asymetrical profile of the GB strains is a criterion for surface cracking initiation. - Abstract: A key element for analyzing the crack initiation in strained polycrystalline alloys is the local quantification of the surface strain distribution according to the grain texture. Using electron backscattered diffraction, the local microstructure was determined to both localize a triple junction and deduce the local Schmid factors. Kernel average misorientation (KAM) was also used to map the areas of defect concentration. The maximum principal strain and the in-plane shear strain were quantified using the biaxial nanogauge. Distortions of the array of nanodots used as spot markers were analyzed near the triple junction. The crystallographic orientation and the surface strain were then investigated both statistically for each grain and locally at the grain boundaries. The superimposition of microstructure and strain maps allows the high strain gradient (reaching 3-fold the applied strain) to be localized at preferential grain boundaries near the triple junction. The Schmid factors and the KAM were compared to the maximum principal strain and the in-plane shear strain respectively. The polycrystalline deformation was attributable first to the rotation of some grains, followed by the elongation of all grains along their preferential activated slip systems.

  18. Plastic strain caused by contraction of pores in polycrystalline graphites

    International Nuclear Information System (INIS)

    Ioka, Ikuo; Yoda, Shinichi; Konishi, Takashi.

    1989-01-01

    The effects of porosity on mechanical properties and deformation behavior of four isotropic polycrystalline graphites were studied. The pore size distributions of the graphites were measured using a conventional mercury penetration technique. The average pore radius of ISO-88 graphite was about one-tenth of that of ISEM-1, IG-11 or IG-15 graphites. Young's modulus of the graphites decreased with increasing porosity. The stress-strain curve of each graphite was measured in its lateral and axial directions. Young's modulus of graphite decreased with increasing load. The plastic strain at a given compressive load was calculated from the stress-strain curve and the initial gradient of the unloading curve at the load. The ratio of lateral plastic strain to axial plastic strain for the graphites was less than 0.5, indicating that the volume of the graphites decreased during compressive loading. By assuming that the volume change was caused by contraction of pores, plastic strain associated with contraction of pores was calculated from the axial plastic strain and lateral plastic strain by slips along the basal planes. The plastic strain increased with increasing axial plastic strain and porosity of graphite. (author)

  19. Triaxial extensometer for volumetric strain measurement in a hydro-compression loading test for foam materials

    International Nuclear Information System (INIS)

    Feng, Bo; Xu, Ming-long; Zhao, Tian-fei; Zhang, Zhi-jun; Lu, Tian-jian

    2010-01-01

    A new strain gauge-based triaxial extensometer (radial extensometers x, y and axial extensometer z) is presented to improve the volumetric strain measurement in a hydro-compression loading test for foam materials. By the triaxial extensometer, triaxial deformations of the foam specimen can be measured directly, from which the volumetric strain is determined. Sensitivities of the triaxial extensometer are predicted using a finite-element model, and verified through experimental calibrations. The axial extensometer is validated by conducting a uniaxial compression test in aluminium foam and comparing deformation measured by the axial extensometer to that by the advanced optical 3D deformation analysis system ARAMIS; the result from the axial extensometer agrees well with that from ARAMIS. A new modus of two-wire measurement and transmission in a hydrostatic environment is developed to avoid the punching and lead sealing techniques on the pressure vessel for the hydro-compression test. The effect of hydrostatic pressure on the triaxial extensometer is determined through an experimental test. An application in an aluminium foam hydrostatic compression test shows that the triaxial extensometer is effective for volumetric strain measurement in a hydro-compression loading test for foam materials

  20. A fiber-optic strain measurement and quench localization system for use in superconducting accelerator dipole magnets

    NARCIS (Netherlands)

    van Oort, J.M.; Scanlan, Ronald M.; ten Kate, Herman H.J.

    1995-01-01

    A novel fiber-optic measurement system for superconducting accelerator magnets is described. The principal component is an extrinsic Fabry-Perot interferometer to determine localized strain and stress in coil windings. The system can be used either as a sensitive relative strain measurement system

  1. Non destructive neutron diffraction measurements of cavities, inhomogeneities, and residual strain in bronzes of Ghiberti's relief from the Gates of Paradise

    Science.gov (United States)

    Festa, G.; Senesi, R.; Alessandroni, M.; Andreani, C.; Vitali, G.; Porcinai, S.; Giusti, A. M.; Materna, T.; Paradowska, A. M.

    2011-03-01

    Quantitative neutron studies of cultural heritage objects provide access to microscopic, mesoscopic, and macroscopic structures in a nondestructive manner. In this paper we present a neutron diffraction investigation of a Ghiberti Renaissance gilded bronze relief devoted to the measurement of cavities and inhomogeneities in the bulk of the sample, along with the bulk phase composition and residual strain distribution. The quantitative measurements allowed the determination of the re-melting parts extension, as well as improving current knowledge about the manufacturing process. The study provides significant and unique information to conservators and restorators about the history of the relief.

  2. Non destructive neutron diffraction measurements of cavities, inhomogeneities, and residual strain in bronzes of Ghiberti's relief from the Gates of Paradise

    International Nuclear Information System (INIS)

    Festa, G.; Senesi, R.; Alessandroni, M.; Andreani, C.; Vitali, G.; Porcinai, S.; Giusti, A. M.; Materna, T.; Paradowska, A. M.

    2011-01-01

    Quantitative neutron studies of cultural heritage objects provide access to microscopic, mesoscopic, and macroscopic structures in a nondestructive manner. In this paper we present a neutron diffraction investigation of a Ghiberti Renaissance gilded bronze relief devoted to the measurement of cavities and inhomogeneities in the bulk of the sample, along with the bulk phase composition and residual strain distribution. The quantitative measurements allowed the determination of the re-melting parts extension, as well as improving current knowledge about the manufacturing process. The study provides significant and unique information to conservators and restorators about the history of the relief.

  3. Stretching positions for the coracohumeral ligament: Strain measurement during passive motion using fresh/frozen cadaver shoulders

    Directory of Open Access Journals (Sweden)

    Izumi Tomoki

    2011-01-01

    Full Text Available Abstract Background Contracture of the coracohumeral ligament is reported to restrict external rotation of the shoulder with arm at the side and restrict posterior-inferior shift of the humeral head. The contracture is supposed to restrict range of motion of the glenohumeral joint. Methods To obtain stretching position of the coracohumeral ligament, strain on the ligament was measured at the superficial fibers of the ligament using 9 fresh/frozen cadaver shoulders. By sequential measurement using a strain gauge, the ligament strain was measured from reference length (L0. Shoulder positions were determined using a 3 Space Tracker System. Through a combination of previously reported coracohumeral stretching positions and those observed in preliminary measurement, ligament strain were measured by passive external rotation from 10° internal rotation, by adding each 10° external rotation, to maximal external rotation. Results Stretching positions in which significantly larger strain were obtained compared to the L0 values were 0° elevation in scapula plane with 40°, 50° and maximum external rotation (5.68%, 7.2%, 7.87%, 30° extension with 50°, maximum external rotation (4.20%, 4.79%, and 30° extension + adduction with 30°, 40°, 50° and maximum external rotation (4.09%, 4.67%, 4.78%, 5.05%(P Conclusions Significant strain of the coracohumeral ligament will be achieved by passive external rotation at lower shoulder elevations, extension, and extension with adduction.

  4. Failure strains and proposed limit strains for an reactor pressure vessel under severe accident conditions

    International Nuclear Information System (INIS)

    Krieg, R.

    2005-01-01

    The local failure strains of essential design elements of a reactor vessel are investigated. The size influence of the structure is of special interest. Typical severe accident conditions including elevated temperatures and dynamic loads are considered. The main part of work consists of test families with specimens under uniaxial and biaxial load. Within one test family the specimen geometry and the load conditions are similar, but the size is varied up to reactor dimensions. Special attention is given to geometries with a hole or a notch causing non-uniform stress and strain distributions typical for the reactor vessel. A key problem is to determine the local failure strain. Here suitable methods had to be developed including the so-called 'vanishing gap method', and the 'forging die method'. They are based on post-test geometrical measurements of the fracture surfaces and reconstructions of the related strain fields using finite element models. The results indicate that stresses versus dimensionless deformations are approximately size independent up to failure for specimens of similar geometry under similar load conditions. Local failure strains could be determined. The values are rather high and size dependent. Statistical evaluation allow the proposal of limit strains which are also size dependent. If these limit strains are not exceeded, the structures will not fracture

  5. Strain measurements at the HDR-pipe-system under LOCA-load: Effects on elbows and displaced weldings

    International Nuclear Information System (INIS)

    Hunger, H.

    1985-01-01

    This paper characterizes some effects which have been detected during strain gauge measurements on a test piping with feed water check valve oscillating under blowdown-load. The ovalization of a pipe elbow subjected to in-plane-bending affects the connected straight pipe; this is shown by means of circumferential stresses. Very high LOCA-load produces plastic strain and changes the pipe dynamics. Artificial displaced welds increase the local strain but no defects have occurred. One example compares stresses from measurement and post-calculation. Moreover there are given some remarks on the optimization of the comparison of measurement and calculation. (orig.)

  6. Heat capacity measurements of Sr{sub 2}RuO{sub 4} under uni-axial strain

    Energy Technology Data Exchange (ETDEWEB)

    Li, You-sheng; Mackenzie, Andrew [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany); University of St. Andrews, School of Physics and Astronomy (United Kingdom); Gibbs, Alexandra [Max Planck Institute for Solid State Research, Stuttgart (Germany); Hicks, Clifford [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany); Nicklas, Michael [University of St. Andrews, School of Physics and Astronomy (United Kingdom)

    2016-07-01

    One of the most-discussed possible pairing symmetries of Sr{sub 2}RuO{sub 4} is p{sub x} ± ip{sub y}. By applying strain along left angle 100 right angle -direction, the degeneracy of the p{sub x} and p{sub y} components is lifted, and thus there should be two critical temperatures (T{sub c}). Hicks et al. have observed an increase of T{sub c} of Sr{sub 2}RuO{sub 4} under both compressive and tensile strains, by measuring the susceptibility, which is sensitive only to the first transition. Their results also indicate, indirectly, that any splitting of T{sub c}s might be small. For a direct test of possible splitting, we measure the heat capacity of Sr{sub 2}RuO{sub 4} under strain. To do so, we are developing an approach to measure heat capacity under non-adiabatic conditions. We have observed an increase of T{sub c} under compressive strain. This is the first thermodynamic evidence of the strain-induced increase in T{sub c} of Sr{sub 2}RuO{sub 4}.

  7. Measurement of mean rotation and strain-rate tensors by using stereoscopic PIV

    DEFF Research Database (Denmark)

    Özcan, Oktay; Meyer, Knud Erik; Larsen, Poul Scheel

    2005-01-01

    A technique is described for measuring the mean velocity gradient (rate-of-displacement) tensor by using a conventional stereoscopic particle image velocimetry (SPIV) system. Planar measurement of the mean vorticity vector, rate-of-rotation and rate-of-strain tensors and the production of turbule...

  8. A Practical Device for Measuring the Luminance Distribution

    Directory of Open Access Journals (Sweden)

    Thijs Kruisselbrink

    2017-06-01

    Full Text Available Various applications in building lighting such as automated daylight systems, dynamic lighting control systems, lighting simulations, and glare analyzes can be optimized using information on the actual luminance distributions of the surroundings. Currently, commercially available luminance distribution measurement devices are often not suitable for these kind of applications or simply too expensive for broad application. This paper describes the development of a practical and autonomous luminance distribution measurement device based on a credit card-sized single-board computer and a camera system. The luminance distribution was determined by capturing High Dynamic Range images and translating the RGB information to the CIE XYZ color space. The High Dynamic Range technology was essential to accurately capture the data needed to calculate the luminance distribution because it allows to capture luminance ranges occurring in real scenarios. The measurement results were represented in accordance with established methods in the field of daylighting. Measurements showed that the accuracy of the luminance distribution measurement device ranged from 5% to 20% (worst case which was deemed acceptable for practical measurements and broad applications in the building realm.

  9. Twin-Core Fiber-Based Mach Zehnder Interferometer for Simultaneous Measurement of Strain and Temperature

    Science.gov (United States)

    Kowal, Dominik; Urbanczyk, Waclaw; Mergo, Pawel

    2018-01-01

    In this paper we present an all-fiber interferometric sensor for the simultaneous measurement of strain and temperature. It is composed of a specially fabricated twin-core fiber spliced between two pieces of a single-mode fiber. Due to the refractive index difference between the two cores in a twin-core fiber, a differential interference pattern is produced at the sensor output. The phase response of the interferometer to strain and temperature is measured in the 850–1250 nm spectral range, showing zero sensitivity to strain at 1000 nm. Due to the significant difference in sensitivities to both parameters, our interferometer is suitable for two-parameter sensing. The simultaneous response of the interferometer to strain and temperature was studied using the two-wavelength interrogation method and a novel approach based on the spectral fitting of the differential phase response. As the latter technique uses all the gathered spectral information, it is more reliable and yields the results with better accuracy. PMID:29558386

  10. Strain analysis of I-c(epsilon) characteristic of YBCO coated conductor measured by a Walters spring

    OpenAIRE

    Sugano, M; Choi, S; Miyazoe, A; Miyamatsu, K; Ando, T; Itoh, K; Kiyoshi, T; Wada, H; Selvamanickam, V

    2008-01-01

    lc-strain characteristic of YBCO coated conductor was measured using a Walters spring (WASP). In this technique, additional bending and thermal strains induced to the YBCO layer should be considered. In order to produce different initial bending strain to the YBCO layer, the conductor was wound around the springs with different diameters and in the different bending directions. The clear evidence was obtained that -strain curves using a WASP strongly depend on the initial bending strain state...

  11. Development of serial measurement system for three-dimensional stress determination by over-coring the strains on borehole wall

    International Nuclear Information System (INIS)

    Itamoto, Masaharu; Kuwabara, Kazumichi; Tanno, Takeo; Nakayama, Yoshiki; Mizuta, Yoshiaki

    2007-01-01

    In order to determine the three-dimensional stress state in serial order, the authors developed the serial measurement system for three-dimensional stress determination by over-coring the strains on the borehole wall. The serial stress measurements give the value of the stresses with high accuracy and bring the regional stress variations. In this paper, the authors describe the studies through FEM analysis on the effect of over-coring diameter, the influence of strain gauge length and the behavior of strain on the borehole wall, induced by biaxial external loading. We developed the multi-strain gauge mounted packer and examined it by measuring the strains on the borehole wall through biaxial loading test. The Laboratory tests showed its applicability to practical use. (author)

  12. Time-dependent strains and stresses in a pumpkin balloon

    Science.gov (United States)

    Gerngross, T.; Xu, Y.; Pellegrino, S.

    This paper presents a study of pumpkin-shaped superpressure balloons consisting of gores made from a thin polymeric film attached to high stiffness meridional tendons This type of design is being used for the NASA ULDB balloons The gore film shows considerable time-dependent stress relaxation whereas the behaviour of the tendons is essentially time-independent Upon inflation and pressurization the instantaneous i e linear-elastic strain and stress distributions in the film show significantly higher values in the meridional direction However over time and due to the biaxial visco-elastic stress relaxation of the the gore material the em hoop strains increase and the em meridional stresses decrease whereas the em remaining strain and stress components remain substantially unchanged These results are important for a correct assessment of the structural integrity of a pumpkin balloon in a long-duration mission both in terms of the material performance and the overall stability of the shape of the balloon An experimental investigation of the time dependence of the biaxial strain distribution in the film of a 4 m diameter 48 gore pumpkin balloon is presented The inflated shape of selected gores has been measured using photogrammetry and the time variation in strain components at some particular points of these gores has been measured under constant pressure and temperature The results show good correlation with a numerical study using the ABAQUS finite-element package that includes a widely used model of

  13. Analysis of simultaneous measurement of temperature and strain using different combinations of FBG

    Science.gov (United States)

    Ashik T., J.; Kachare, Nitin; Kalyani bai, K.; Kumar, D. Sriram

    2017-06-01

    The Fiber Bragg Grating (FBG) can be used for measuring temperature and or strain. In this paper analysis of different combinations of FBG is made. Certain parameters of FBG are considered such as Bandwidth, Side lobes, Peak power, and Sensitivity. Simultaneous measurement of temperature and strain is made using two combinations of FBG. The setup is simulated using two software. Optigrating 4.2.2 is used for designing different types of gratings such as Uniform, Apodized, Tilted and Superstructure. After designing, these files are exported to Optisystem 12 to simulate the spectrum and to observe the parameters.

  14. Job Strain and Casual Blood Pressure Distribution: Looking beyond the Adjusted Mean and Taking Gender, Age, and Use of Antihypertensives into Account. Results from ELSA-Brasil

    Science.gov (United States)

    Juvanhol, Leidjaira Lopes; Melo, Enirtes Caetano Prates; Carvalho, Marilia Sá; Chor, Dóra; Mill, José Geraldo; Griep, Rosane Härter

    2017-01-01

    Methodological issues are pointed to as the main sources of inconsistencies in studies about the association between job strain and blood pressure (BP)/hypertension. Our aim was to analyze the relationship between job strain and the whole BP distribution, as well as potential differences by gender, age, and use of antihypertensives. Additionally, we addressed issues relating to the operationalization of the exposure and outcome variables that influence the study of their inter-relations. We evaluated the baseline date of 12,038 participants enrolled in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) (2008–2010), a multicenter cohort study of 35–74-year-old civil servants. Job strain was assessed by the Demand-Control-Support Questionnaire. The distribution of casual BP by categories of job strain was compared by a combination of exploratory techniques. Participants were classified into three subgroups (normotensives, medicated hypertensives, and unmedicated hypertensives), and analyses were stratified by gender and age. The relationship between job strain and casual BP varied along the whole outcome distribution. Hypertensive participants had greater differences in casual BP by job strain category, especially medicated hypertensives. Differences in casual BP were also greater for systolic than for diastolic BP and for older participants. No differences were encountered by gender. The exclusion of participants susceptible to misclassification for the exposure and outcome variables increased the differences observed between the categories of low and high job strain. In conclusion, the relationship between job strain and casual BP varied along the whole outcome distribution and by use of antihypertensive drugs, age, and BP parameter evaluated. Misclassification for exposure and outcome variables should be considered in analyses of this topic. PMID:28441727

  15. Strain ratio measurement of femoral cartilage by real-time elastosonography: preliminary results

    International Nuclear Information System (INIS)

    Ipek, Ali; Unal, Ozlem; Kartal, Merve Gulbiz; Arslan, Halil; Isik, Cetin; Bozkurt, Murat

    2015-01-01

    The purpose of this study was to evaluate strain ratio measurement of femoral cartilage using real-time elastosonography. Twenty-five patients with femoral cartilage pathology on MRI (study group) were prospectively compared with 25 subjects with normal findings on MRI (control group) using real-time elastosonography. Strain ratio measurements of pathologic and normal cartilage were performed and compared, both within the study group and between the two groups. Elastosonography colour-scale coding showed a colour change from blue to red in pathologic cartilage and only blue colour-coding in normal cartilage. In the study group, the median strain ratio was higher in pathologic cartilage areas compared to normal areas (median, 1.49 [interquartile range, 0.80-2.53] vs. median, 0.01 [interquartile range, 0.01-0.01], p < 0.001, respectively). The median strain ratio of the control group was 0.01 (interquartile range, 0.01-0.01), and there was no significant difference compared to normal areas of the study group. There was, however, a significant difference between the control group cartilage and pathologic cartilage of the study group (p < 0.001). Elastosonography may be an effective, easily accessible, and relatively simple tool to demonstrate pathologic cartilage and to differentiate it from normal cartilage in the absence of advanced imaging facility such as MRI. (orig.)

  16. Finite Element Simulation of Temperature and Strain Distribution during Friction Stir Welding of AA2024 Aluminum Alloy

    Science.gov (United States)

    Jain, Rahul; Pal, Surjya Kanta; Singh, Shiv Brat

    2017-02-01

    Friction Stir Welding (FSW) is a solid state joining process and is handy for welding aluminum alloys. Finite Element Method (FEM) is an important tool to predict state variables of the process but numerical simulation of FSW is highly complex due to non-linear contact interactions between tool and work piece and interdependency of displacement and temperature. In the present work, a three dimensional coupled thermo-mechanical method based on Lagrangian implicit method is proposed to study the thermal history, strain distribution and thermo-mechanical process in butt welding of Aluminum alloy 2024 using DEFORM-3D software. Workpiece is defined as rigid-visco plastic material and sticking condition between tool and work piece is defined. Adaptive re-meshing is used to tackle high mesh distortion. Effect of tool rotational and welding speed on plastic strain is studied and insight is given on asymmetric nature of FSW process. Temperature distribution on the workpiece and tool is predicted and maximum temperature is found in workpiece top surface.

  17. A strain gauge

    DEFF Research Database (Denmark)

    2016-01-01

    The invention relates to a strain gauge of a carrier layer and a meandering measurement grid positioned on the carrier layer, wherein the strain gauge comprises two reinforcement members positioned on the carrier layer at opposite ends of the measurement grid in the axial direction....... The reinforcement members are each placed within a certain axial distance to the measurement grid with the axial distance being equal to or smaller than a factor times the grid spacing. The invention further relates to a multi-axial strain gauge such as a bi-axial strain gauge or a strain gauge rosette where each...... of the strain gauges comprises reinforcement members. The invention further relates to a method for manufacturing a strain gauge as mentioned above....

  18. Measuring Local Strain Rates In Ductile Shear Zones: A New Approach From Deformed Syntectonic Dykes

    Science.gov (United States)

    Sassier, C.; Leloup, P.; Rubatto, D.; Galland, O.; Yue, Y.; Ding, L.

    2006-12-01

    At the Earth surface, deformation is mostly localized in fault zones in between tectonic plates. In the upper crust, the deformation is brittle and the faults are narrow and produce earthquakes. In contrast, deformation in the lower ductile crust results in larger shear zones. While it is relatively easy to measure in situ deformation rates at the surface using for example GPS data, it is more difficult to determinate in situ values of strain rate in the ductile crust. Such strain rates can only be estimated in paleo-shear zones. Various methods have been used to assess paleo-strain rates in paleo-shear zones. For instance, cooling and/or decompression rates associated with assumptions on geothermic gradients and shear zone geometry can lead to such estimates. Another way to estimate strain rates is the integration of paleo-stress measurements in a power flow law. But these methods are indirect and imply strong assumptions. Dating of helicitic garnets or syntectonic fibres are more direct estimates. However these last techniques have been only applied in zones of low deformation and not in major shear zones. We propose a new direct method to measure local strain rates in major ductile shear zones from syntectonic dykes by coupling quantification of deformation and geochronology. We test our method in a major shear zone in a well constrained tectonic setting: the Ailao-Shan - Red River Shear Zone (ASRRsz) located in SE Asia. For this 10 km wide shear zone, large-scale fault rates, determined in three independent ways, imply strain rates between 1.17×10^{-13 s-1 and 1.52×10^{-13 s-1 between 35 and 16 Ma. Our study focused on one outcrop where different generations of syntectonic dykes are observed. First, we quantified the minimum shear strain γ for each dyke using several methods: (1) by measuring the stretching of dykes with a surface restoration method (2) by measuring the final angle of the dykes with respect to the shear direction and (3) by combining the two

  19. Spectral-Domain Measurement of Strain Sensitivity of a Two-Mode Birefringent Side-Hole Fiber

    Directory of Open Access Journals (Sweden)

    Waclaw Urbanczyk

    2012-09-01

    Full Text Available The strain sensitivity of a two-mode birefringent side-hole fiber is measured in the spectral domain. In a simple experimental setup comprising a broadband source, a polarizer, a two-mode birefringent side-hole fiber under varied elongations, an analyzer and a compact spectrometer, the spectral interferograms are resolved. These are characterized by the equalization wavelength at which spectral interference fringes have the highest visibility (the largest period due to the zero group optical path difference between the fundamental, the LP01 mode and the higher-order, the LP11 mode. The spectral interferograms with the equalization wavelength are processed to retrieve the phase as a function of the wavelength. From the retrieved phase functions corresponding to different elongations of a two-mode birefringent side-hole fiber under test, the spectral strain sensitivity is obtained. Using this approach, the intermodal spectral strain sensitivity was measured for both x and y polarizations. Moreover, the spectral polarimetric sensitivity to strain was measured for the fundamental mode when a birefringent delay line was used in tandem with the fiber. Its spectral dependence was also compared with that obtained from a shift of the spectral interferograms not including the equalization wavelength, and good agreement was confirmed.

  20. Segregation of genes from donor strain during the production of recombinant congenic strains.

    Science.gov (United States)

    van Zutphen, L F; Den Bieman, M; Lankhorst, A; Demant, P

    1991-07-01

    Recombinant congenic strains (RCS) constitute a set of inbred strains which are designed to dissect the genetic control of multigenic traits, such as tumour susceptibility or disease resistance. Each RCS contains a small fraction of the genome of a common donor strain, while the majority of genes stem from a common background strain. We tested at two stages of the inbreeding process in 20 RCS, derived from BALB/cHeA and STS/A, to see whether alleles from the STS/A donor strain are distributed over the RCS in a ratio as would theoretically be expected. Four marker genes (Pep-3; Pgm-1; Gpi-1 and Es-3) located at 4 different chromosomes were selected and the allelic distribution was tested after 3-4 and after 12 generations of inbreeding. The data obtained do not significantly deviate from the expected pattern, thus supporting the validity of the concept of RCS.

  1. Residual strain sensor using Al-packaged optical fiber and Brillouin optical correlation domain analysis.

    Science.gov (United States)

    Choi, Bo-Hun; Kwon, Il-Bum

    2015-03-09

    We propose a distributed residual strain sensor that uses an Al-packaged optical fiber for the first time. The residual strain which causes Brillouin frequency shifts in the optical fiber was measured using Brillouin optical correlation domain analysis with 2 cm spatial resolution. We quantified the Brillouin frequency shifts in the Al-packaged optical fiber by the tensile stress and compared them for a varying number of Al layers in the optical fiber. The Brillouin frequency shift of an optical fiber with one Al layer had a slope of 0.038 MHz/με with respect to tensile stress, which corresponds to 78% of that for an optical fiber without Al layers. After removal of the stress, 87% of the strain remained as residual strain. When different tensile stresses were randomly applied, the strain caused by the highest stress was the only one detected as residual strain. The residual strain was repeatedly measured for a time span of nine months for the purpose of reliability testing, and there was no change in the strain except for a 4% reduction, which is within the error tolerance of the experiment. A composite material plate equipped with our proposed Al-packaged optical fiber sensor was hammered for impact experiment and the residual strain in the plate was successfully detected. We suggest that the Al-packaged optical fiber can be adapted as a distributed strain sensor for smart structures, including aerospace structures.

  2. A study on plastic strain accumulation caused by traveling of temperature distribution synchronizing with temperature rise

    International Nuclear Information System (INIS)

    Okajima, Satoshi

    2016-01-01

    The prevention of excessive deformation by thermal ratcheting is important in the design of high-temperature components of fast breeder reactors (FBR). This includes evaluation methods for a new type of thermal ratcheting caused by an axial traveling of temperature distribution, which corresponds to moving-up of liquid sodium surface in startup phase. Long range traveling of the axial temperature distribution brings flat plastic deformation profile in wide range. Therefore, at the center of this range, residual stress that brings shakedown behavior does not accumulate. As a result, repeating of this temperature traveling brings continuous accumulation of the plastic strain, even if there is no primary stress. In contrast, in the case with short range traveling, residual stress is caused by constraint against elastic part, and finally it results in shakedown. Because of this mechanism, we supposed that limit for the shakedown behavior depends on distance from the elastic part (i.e. half length of region with plastic deformation). In this paper, we examined characteristics of the accumulation of the plastic strain caused by realistic heat transients, namely, traveling of temperature distribution synchronizing with temperature rise. This examination was based on finite element analyses using elastic-perfectly plastic material. As a result, we confirmed that the shakedown limit depends not on the traveling range of the temperature distribution but the plastic deformation range, which was predicted by the elastic analysis. In the actual application, we can control the plastic deformation range by changing rate of the moving-up of liquid sodium surface. (author)

  3. Effect of nonlinear stress-strain relationship on bending strength of isotropic graphite

    International Nuclear Information System (INIS)

    Arai, Taketoshi; Oku, Tatsuo

    1978-05-01

    Four-point bending tests were made on rectangular isotropic 7477PT graphite specimens of different sizes to observe the relation between load and outermost fiber strain. Analytical methods, allowing for nonlinear stress-strain relationships different between tension and compression, were developed for calculating the fiber stress distribution in a beam and the failure probability based on the Weibull statistical theory for bending fracture. With increase of the stress, the stress-strain curves for tension deviate from the linearity and also from those for compression. The true bending strengths of the rectangular bars are 10 -- 20 percent lower than elastic bending strengths. Revised Weibull theory gives failure probability distributions agreeing with measured ones, compared with the theory based on elastic behavior. (auth.)

  4. Distributed Long-Gauge Optical Fiber Sensors Based Self-Sensing FRP Bar for Concrete Structure

    OpenAIRE

    Tang, Yongsheng; Wu, Zhishen

    2016-01-01

    Brillouin scattering-based distributed optical fiber (OF) sensing technique presents advantages for concrete structure monitoring. However, the existence of spatial resolution greatly decreases strain measurement accuracy especially around cracks. Meanwhile, the brittle feature of OF also hinders its further application. In this paper, the distributed OF sensor was firstly proposed as long-gauge sensor to improve strain measurement accuracy. Then, a new type of self-sensing fiber reinforced p...

  5. Recent Progress in Distributed Fiber Optic Sensors

    Directory of Open Access Journals (Sweden)

    Xiaoyi Bao

    2012-06-01

    Full Text Available Rayleigh, Brillouin and Raman scatterings in fibers result from the interaction of photons with local material characteristic features like density, temperature and strain. For example an acoustic/mechanical wave generates a dynamic density variation; such a variation may be affected by local temperature, strain, vibration and birefringence. By detecting changes in the amplitude, frequency and phase of light scattered along a fiber, one can realize a distributed fiber sensor for measuring localized temperature, strain, vibration and birefringence over lengths ranging from meters to one hundred kilometers. Such a measurement can be made in the time domain or frequency domain to resolve location information. With coherent detection of the scattered light one can observe changes in birefringence and beat length for fibers and devices. The progress on state of the art technology for sensing performance, in terms of spatial resolution and limitations on sensing length is reviewed. These distributed sensors can be used for disaster prevention in the civil structural monitoring of pipelines, bridges, dams and railroads. A sensor with centimeter spatial resolution and high precision measurement of temperature, strain, vibration and birefringence can find applications in aerospace smart structures, material processing, and the characterization of optical materials and devices.

  6. Measurement of light-atom distributions in solids

    International Nuclear Information System (INIS)

    Blewer, R.S.

    1977-01-01

    We have developed a sensitive technique that is capable of nondestructively measuring the abundance and depth-distribution of isotopes of hydrogen or helium imbedded in a solid. The measurement is a form of ion-backscattering spectrometry which uses protons to probe within approximately 10μm of the surface of a solid. By analyzing the energy of the backscattered protons we can determine the number of atoms of a given mass present at various depths in the target material. This method permits detection of the lightest elements (i.e., those most difficult to detect by conventional ion-backscattering spectrometry) without sacrificing the capability of revealing the abundance and depth-distribution of heavier elements. For example, we have measured the initial distribution of helium implanted in a metal, then in subsequent measurements kept track of the helium migration

  7. Strain features and condition assessment of orthotropic steel deck cable-supported bridges subjected to vehicle loads by using dense FBG strain sensors

    Science.gov (United States)

    Wei, Shiyin; Zhang, Zhaohui; Li, Shunlong; Li, Hui

    2017-10-01

    Strain is a direct indicator of structural safety. Therefore, strain sensors have been used in most structural health monitoring systems for bridges. However, until now, the investigation of strain response has been insufficient. This paper conducts a comprehensive study of the strain features of the U ribs and transverse diaphragm on an orthotropic steel deck and proposes a statistical paradigm for crack detection based on the features of vehicle-induced strain response by using the densely distributed optic fibre Bragg grating (FBG) strain sensors. The local feature of strain under vehicle load is highlighted, which enables the use of measurement data to determine the vehicle loading event and to make a decision regarding the health status of a girder near the strain sensors via technical elimination of the load information. Time-frequency analysis shows that the strain contains three features: the long-term trend item, the short-term trend item, and the instantaneous vehicle-induced item (IVII). The IVII is the wheel-induced strain with a remarkable local feature, and the measured wheel-induced strain is only influenced by the vehicle near the FBG sensor, while other vehicles slightly farther away have no effect on the wheel-induced strain. This causes the local strain series, among the FBG strain sensors in the same transverse locations of different cross-sections, to present similarities in shape to some extent and presents a time delay in successive order along the driving direction. Therefore, the strain series induced by an identical vehicle can be easily tracked and compared by extracting the amplitude and calculating the mutual ratio to eliminate vehicle loading information, leaving the girder information alone. The statistical paradigm for crack detection is finally proposed, and the detection accuracy is then validated by using dense FBG strain sensors on a long-span suspension bridge in China.

  8. Neutron Diffraction Residual Strain Tensor Measurements Within The Phase IA Weld Mock-up Plate P-5

    Energy Technology Data Exchange (ETDEWEB)

    Hubbard, Camden R [ORNL

    2011-09-01

    Oak Ridge National Laboratory (ORNL) has worked with NRC and EPRI to apply neutron and X-ray diffraction methods to characterize the residual stresses in a number of dissimilar metal weld mockups and samples. The design of the Phase IA specimens aimed to enable stress measurements by several methods and computational modeling of the weld residual stresses. The partial groove in the 304L stainless steel plate was filled with weld beads of Alloy 82. A summary of the weld conditions for each plate is provided in Table 1. The plates were constrained along the long edges during and after welding by bolts with spring-loaded washers attached to the 1-inch thick Al backing plate. The purpose was to avoid stress relief due to bending of the welded stainless steel plate. The neutron diffraction method was one of the methods selected by EPRI for non-destructive through thickness strain and stress measurement. Four different plates (P-3 to P-6) were studied by neutron diffraction strain mapping, representing four different welding conditions. Through thickness neutron diffraction strain mappings at NRSF2 for the four plates and associated strain-free d-zero specimens involved measurement along seven lines across the weld and at six to seven depths. The mountings of each plate for neutron diffraction measurements were such that the diffraction vector was parallel to each of the three primary orthogonal directions of the plate: two in-plane directions, longitudinal and transverse, and the direction normal to the plate (shown in left figure within Table 1). From the three orthogonal strains for each location, the residual stresses along the three plate directions were calculated. The principal axes of the strain and stress tensors, however, need not necessarily align with the plate coordinate system. To explore this, plate P-5 was selected for examination of the possibility that the principal axes of strain are not along the sample coordinate system axes. If adequate data could

  9. Strain distribution during tensile deformation of nanostructured aluminum samples

    DEFF Research Database (Denmark)

    Kidmose, Jacob; Lu, L.; Winther, Grethe

    2012-01-01

    To optimize the mechanical properties, especially formability, post-process deformation by cold rolling in the range 5–50 % reduction was applied to aluminum sheets produced by accumulative roll bonding to an equivalent strain of 4.8. During tensile testing high resolution maps of the strain...

  10. In situ study of annealing-induced strain relaxation in diamond nanoparticles using Bragg coherent diffraction imaging

    Directory of Open Access Journals (Sweden)

    S. O. Hruszkewycz

    2017-02-01

    Full Text Available We observed changes in morphology and internal strain state of commercial diamond nanocrystals during high-temperature annealing. Three nanodiamonds were measured with Bragg coherent x-ray diffraction imaging, yielding three-dimensional strain-sensitive images as a function of time/temperature. Up to temperatures of 800 °C, crystals with Gaussian strain distributions with a full-width-at-half-maximum of less than 8×10−4 were largely unchanged, and annealing-induced strain relaxation was observed in a nanodiamond with maximum lattice distortions above this threshold. X-ray measurements found changes in nanodiamond morphology at temperatures above 600 °C that are consistent with graphitization of the surface, a result verified with ensemble Raman measurements.

  11. Progress of a Cross-Correlation Based Optical Strain Measurement Technique for Detecting Radial Growth on a Rotating Disk

    Science.gov (United States)

    Clem, Michelle M.; Woike, Mark R.; Abdul-Aziz, Ali

    2014-01-01

    The Aeronautical Sciences Project under NASA's Fundamental Aeronautics Program is interested in the development of novel measurement technologies, such as optical surface measurements for the in situ health monitoring of critical constituents of the internal flow path. In situ health monitoring has the potential to detect flaws, i.e. cracks in key components, such as engine turbine disks, before the flaws lead to catastrophic failure. The present study, aims to further validate and develop an optical strain measurement technique to measure the radial growth and strain field of an already cracked disk, mimicking the geometry of a sub-scale turbine engine disk, under loaded conditions in the NASA Glenn Research Center's High Precision Rotordynamics Laboratory. The technique offers potential fault detection by imaging an applied high-contrast random speckle pattern under unloaded and loaded conditions with a CCD camera. Spinning the cracked disk at high speeds (loaded conditions) induces an external load, resulting in a radial growth of the disk of approximately 50.0-µm in the flawed region and hence, a localized strain field. When imaging the cracked disk under static conditions, the disk will be undistorted; however, during rotation the cracked region will grow radially, thus causing the applied particle pattern to be 'shifted'. The resulting particle displacements between the two images is measured using the two-dimensional cross-correlation algorithms implemented in standard Particle Image Velocimetry (PIV) software to track the disk growth, which facilitates calculation of the localized strain field. A random particle distribution is adhered onto the surface of the cracked disk and two bench top experiments are carried out to evaluate the technique's ability to measure the induced particle displacements. The disk is shifted manually using a translation stage equipped with a fine micrometer and a hotplate is used to induce thermal growth of the disk, causing the

  12. Micro-mechanics of polycrystals subjected to small strains

    International Nuclear Information System (INIS)

    Sauzay, M.

    2009-04-01

    The author proposes an overview of the different research works he performed during several years. His aim is the understanding and the modelling of plasticity and damage mechanisms in metal polycrystals subjected to small strains, mainly under long duration creep and fatigue. Three topics are more particularly developed: the distribution of mechanical fields in polycrystals subjected to small strains, the strain localisation at the grain scale, and the softening of martensitic steels under creep or fatigue loadings. For each of these topics, the author reports the investigation of microstructure and of damage and strain mechanisms (mechanical tests, microstructure observations), the modelling of these mechanisms (based on continuum mechanics, crystalline elasto-plasticity, finite elements calculations, theory of dislocations and diffusion), and the validation of these predictions at a microscopic and macroscopic scale by comparison with experimental measurements and observations

  13. A Monte Carlo simulation on critical current distribution of bent-damaged multifilamentary Bi2223 composite tape

    International Nuclear Information System (INIS)

    Ochiai, S.; Okuda, H.; Fujimoto, M.; Shin, J.K.; Oh, S.S.; Ha, D.W.

    2011-01-01

    We simulate critical current distribution of bent-damaged Bi2223 composite tape. We use a Monte Carlo method and a damage evolution model for simulation. With the present simulation approach, experimental results are described well. Critical current distribution stems mainly from difference in damage evolution. It was attempted to reproduce the measured critical current (I c ) distributions of the Bi2223 composite tape bent by 0-0.833% by simulation. Simulation was carried out with a Monte Carlo method in combination with a model that correlates the critical current to damage evolution. Two variables that differ from specimen to specimen were input in the simulation. One was the damage strain parameter, with which the difference in extent of damage among specimens was expressed. Another was the original critical current (I c0 ) values at zero bending strain. With the present simulation approach, the measured distributions of critical current at various bending strains, and the measured variations of average and coefficient of variation of critical current values with increasing bending strain were reproduced well.

  14. Multi-Functional Measurement Using a Single FBG Sensor

    NARCIS (Netherlands)

    Mizutani, Y.; Groves, R.M.

    2011-01-01

    This paper describes the measurement of average strain, strain distribution and vibration of a cantilever beam made of Carbon Fiber Reinforced Plastics (CFRP), using a single Fibre Bragg Grating (FBG) sensor mounted on the beam surface. Average strain is determined from the displacement of the peak

  15. Flight demonstration of aircraft fuselage and bulkhead monitoring using optical fiber distributed sensing system

    Science.gov (United States)

    Wada, Daichi; Igawa, Hirotaka; Tamayama, Masato; Kasai, Tokio; Arizono, Hitoshi; Murayama, Hideaki; Shiotsubo, Katsuya

    2018-02-01

    We have developed an optical fiber distributed sensing system based on optical frequency domain reflectometry (OFDR) that uses long-length fiber Bragg gratings (FBGs). This technique obtains strain data not as a point data from an FBG but as a distributed profile within the FBG. This system can measure the strain distribution profile with an adjustable high spatial resolution of the mm or sub-mm order in real-time. In this study, we applied this OFDR-FBG technique to a flying test bed that is a mid-sized jet passenger aircraft. We conducted flight tests and monitored the structural responses of a fuselage stringer and the bulkhead of the flying test bed during flights. The strain distribution variations were successfully monitored for various events including taxiing, takeoff, landing and several other maneuvers. The monitoring was effective not only for measuring the strain amplitude applied to the individual structural parts but also for understanding the characteristics of the structural responses in accordance with the flight maneuvers. We studied the correlations between various maneuvers and strains to explore the relationship between the operation and condition of aircraft.

  16. New strain measurement method at axial tensile test of thin films through direct imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Jong-Eun [Department of Automotive Engineering, Seoul National Uinversity of Technolgy, 172 Gongneung-2 Dong, Nowon-Gu, Seoul (Korea, Republic of); Park, Jun-Hyub [Department of Mechatronics Engineering, College of Engineering, Tongmyong University, 535, Yongdang-Dong, Nam-Gu, Busan 608-711 (Korea, Republic of); Kang, Dong-Joong [School of Mechanical Eng., Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of)], E-mail: jhyubpark@korea.com

    2008-09-07

    This paper proposes a new method for measuring strain during a tensile test of the specimen with micrometre size through direct imaging. A specimen was newly designed for adoption of direct imaging which was the main contribution of the proposed system. The structure of the specimen has eight indicators that make it possible to adopt direct imaging and it is fabricated using the same process of microelectromechanical system (MEMS) devices to guarantee the feasibility of the tensile test. We implemented a system for non-contact in situ measurement of strain with the specimen, the image-based displacement measurement system. Extension of the gauge length in the specimen could be found robustly by computing the positions of the eight rectangular-shape indicators on the image. Also, for an easy setup procedure, the region of interest was found automatically through the analysis of the edge projection profile along the horizontal direction. To gain confidence in the reliability of the system, the tensile test for the Al-3%Ti thin film was performed, which is widely used as a material in MEMS devices. Tensile tests were performed and displacements were measured using the proposed method and also the capacitance type displacement sensor for comparison. It is demonstrated that the new strain measurement system can be effectively used in the tensile test of the specimen at microscale with easy setup and better accuracy.

  17. The applicability of the Poisson distribution in radiochemical measurements

    International Nuclear Information System (INIS)

    Luthardt, M.; Proesch, U.

    1980-01-01

    The fact that, on principle, the Poisson distribution describes the statistics of nuclear decay is generally accepted. The applicability of this distribution to nuclear radiation measurements has recently been questioned. Applying the chi-squared test for goodness of fit on the analogy of the moving average, at least 3 cases may be distinguished, which lead to an incorrect rejection of the Poisson distribution for measurements. Examples are given. Distributions, which make allowance for special parameters, should only be used after careful examination of the data with regard to other interfering effects. The Poisson distribution will further on be applicable to many simple measuring operations. Some basic equations for the analysis of poisson-distributed data are given. (author)

  18. Direct production of feruloyl oligosaccharides and hemicellulase inducement and distribution in a newly isolated Aureobasidium pullulans strain.

    Science.gov (United States)

    Yu, Xiao-hong; Gu, Zhen-xin

    2014-02-01

    Studies were carried out to screen and identify strains that are able to directly produce ferulic oligosaccharides (FOs) from wheat bran (WB). The inducement and distribution of hemicellulases from strain 2012, which was identified as a non-melanin secreting strain of Aureobasidium pullulans (A. pullulans), were also determined. In a 60 g/L WB solution, A. pullulans could produce 545 nmol/L FOs, 64.12 IU/mL xylanase and 0.14 IU/mL ferulic acid esterase (FAE). A. pullulans was cultivated in media with WB, glucose, xylose, sucrose, lactose or xylan as the carbon source, and hemicellulases were mainly induced by xylan and WB and inhibited by glucose and sucrose. Xylanase and FAE were mainly present in the culture filtrate, xylosidase in the hyphal filaments and arabinofuranosidase was a membrane-bound enzyme. The yield of FOs was positively correlated to the hemicellulases activity, and significantly positively (P < 0.05) correlated to the xylanase activity (r = 0.992).

  19. Strain measurements of temperatures up to 3000C in a concrete structure

    International Nuclear Information System (INIS)

    Schittenhelm, Ch.

    1975-10-01

    Strain measurements in a concrete structure representing a cylindrical section of a Prestressed Concrete Reactor Vessel with hot liner, were made. In order to interpret these values in terms of strain and stress in a three dimensional structure, the gauge characteristics as well as the material date of the concrete have to be known in great detail. The paper deals with the performance of different gauges embedded in small concrete blocks and others of the same type embedded in the test ring. Temperature resistance, long-time performance, electrical drift and hysteresis of the gauges were investigated. (author)

  20. Influence of undersized cementless hip stems on primary stability and strain distribution.

    Science.gov (United States)

    Fottner, Andreas; Woiczinski, Matthias; Kistler, Manuel; Schröder, Christian; Schmidutz, Tobias F; Jansson, Volkmar; Schmidutz, Florian

    2017-10-01

    Undersizing of cementless hip stems is a risk factor for aseptic loosening and early subsidence. The purpose of this study was to evaluate the effects of undersized stems and determine whether a biomechanical study can predict the clinical results. Three consecutive sizes of a clinically proven stem (CLS Spotorno) were implanted into six composite femora (size large, Sawbones ® ), respectively. According to the Canal Fill Index (CFI), two stems (size 11.25 and 12.5) were undersized (CFI  80%). The primary stability was evaluated by measurement of 3-dimensional (3D)-micromotions under physiological adapted load and surface strains were recorded before and after implantation to detect stress-shielding processes. Both undersized stems revealed significantly higher micromotions in all regions compared to the appropriate stem. The highest micromotions were registered at the distal tip of the three stem sizes. The changes in surface strain did not show a significant difference between the three stem sizes, but the highest strain reduction was observed proximally indicating a tendency for stress shielding. This study confirms the clinical assumption that undersized stem result in a significantly reduced primary stability. Furthermore, in vitro studies allow to determine the effects of undersizing and stress shielding processes.

  1. Measuring distributed leadership agency in a hospital context

    DEFF Research Database (Denmark)

    Jønsson, Thomas; Unterrainer, Christine; Jeppesen, Hans Jeppe

    2016-01-01

    and valid quantitative instrument that measures how much employees’ at all hierarchical levels are involved in concrete leadership activities in the hospital context. Taking a normative perspective we could show that Distributed Leadership – measured with the DLA-questionnaire – has positive effects......Purpose: The purpose of this study is to develop and validate an instrument that can measure Distributed Leadership as employees’ active participation in distributed leadership tasks. We designate this as the Distributed Leadership Agency (DLA). Methodology: Data were collected throughout all......, discriminant and convergent validity, and ANOVAs were applied to analyze group differences in DLA. Findings: The identified uni-dimensional questionnaire consists of seven items, as it is different from, but associated with, empowering leadership, organizational influence, attitude to participation and trust...

  2. Evaluation of Strain Distribution in Bone around Implant in Treatment Design of Overdentures Using Computer and Modeling of Finite Elements

    Directory of Open Access Journals (Sweden)

    Masoumeh Khoshhal

    2016-03-01

    Full Text Available Introduction: Introduction: Few studies have investigated the distribution of stress around implants. In this study the distribution of stress in bones around implants was investigated in five overdenture (OD treatment designs including OD-1, OD-2, OD-3, OD-4 and OD-5. Materials and methods: The Catia modeling software was used in order to simulate the tooth/implant model and bone. First, the borders of cancellous and cortical bone in each section of the CT images were attained by Photoshop software. Then, modeling softwares SolidWorks and NUMBER were applied to make the final three-dimensional model of jaw. Finally, the amount of stress on the surface of bone/implant was studied by means of stress analysis software (Ansys v11.0. Results: Protrusive movements of implants B and D in OD-1 showed the highest amount of strain, 2435 εµ. Also, high amounts of strain, 1668 and 1557 εµwere observed in OD-1 and OD-2 designs in lateral movements respectively. Conclusion: The bottom line is that no forces to the extent of destruction based on the Ferost model were found for these designs. The highest amount of strain occurred in OD-1 design, which is held in mild overload window. Moreover, the amounts of strain in the rest of designs investigated were in adaptive window.

  3. Evaluation of Strain Distribution in Bone around Implant in Treatment Design of Overdentures Using Computer and Modeling of Finite Elements

    Directory of Open Access Journals (Sweden)

    Masoumeh Khoshhal

    2015-12-01

    Full Text Available Introduction: Introduction: Few studies have investigated the distribution of stress around implants. In this study the distribution of stress in bones around implants was investigated in five overdenture (OD treatment designs including OD-1, OD-2, OD-3, OD-4 and OD-5. Materials and methods: The Catia modeling software was used in order to simulate the tooth/implant model and bone. First, the borders of cancellous and cortical bone in each section of the CT images were attained by Photoshop software. Then, modeling softwares SolidWorks and NUMBER were applied to make the final three-dimensional model of jaw. Finally, the amount of stress on the surface of bone/implant was studied by means of stress analysis software (Ansys v11.0. Results: Protrusive movements of implants B and D in OD-1 showed the highest amount of strain, 2435 εµ. Also, high amounts of strain, 1668 and 1557 εµwere observed in OD-1 and OD-2 designs in lateral movements respectively. Conclusion: The bottom line is that no forces to the extent of destruction based on the Ferost model were found for these designs. The highest amount of strain occurred in OD-1 design, which is held in mild overload window. Moreover, the amounts of strain in the rest of designs investigated were in adaptive window.

  4. Residual strain dependence on the matrix structure in RHQ-Nb3Al wires by neutron diffraction measurement

    International Nuclear Information System (INIS)

    Jin Xinzhe; Nakamoto, Tatsushi; Tsuchiya, Kiyosumi; Ogitsu, Toru; Yamamoto, Akira; Ito, Takayoshi; Harjo, Stefanus; Kikuchi, Akihiro; Takeuchi, Takao; Hemmi, Tsutomu

    2012-01-01

    We prepared three types of non-Cu RHQ-Nb 3 Al wire sample with different matrix structures: an all-Ta matrix, a composite matrix of Nb and Ta with a Ta inter-filament, and an all-Nb matrix. Neutron diffraction patterns of the wire samples were measured at room temperature in the J-PARC ‘TAKUMI’. To obtain the residual strains of the materials, we estimated the lattice constant a by multi-peak analysis in the wires. A powder sample of each wire was measured, where the powder was considered to be strain free. The grain size of all the powder samples was below 0.02 mm. For the wire sample with the all-Nb matrix, we also obtained the lattice spacing d by a single-peak analysis. The residual strains of the Nb 3 Al filament were estimated from the two analysis results and were compared. The resulting residual strains obtained from the multi-peak analysis showed a good accuracy with small standard deviation. The multi-peak analysis results for the residual strains of the Nb 3 Al filaments in the three samples (without Cu plating) were all tensile residual strain in the axial direction, of 0.12%, 0.12%, and 0.05% for the all-Ta matrix, the composite matrix, and the all-Nb matrix, respectively. The difference in the residual strain of the Nb 3 Al filament between the composite and all-Nb matrix samples indicates that the type of inter-filament material shows a great effect on the residual strain. In this paper, we report the method of measurement, method of analysis, and results for the residual strain in the three types of non-Cu RHQ-Nb 3 Al wires. (paper)

  5. A fiber optic strain measurement and quench localization for use in superconducting accelerator dipole magnets

    International Nuclear Information System (INIS)

    van Oort, J.M.; Scanlan, R.M.; ten Kate, H.H.J.

    1994-01-01

    A novel fiber-optic measurement system for superconducting accelerator magnets is described. The principal component is an extrinsic Fabry-Perot Interferometer to determine localized strain and stress in coil windings. The system can be used either as a sensitive relative strain measurement system or as an absolute strain detector. Combined, one can monitor the mechanical behaviour of the magnet system over time during construction, long time storage and operation. The sensing mechanism is described, together with various tests in laboratory environments. The test results of a multichannel test matrix to be incorporated first in the dummy coils and then in the final version of a 13T Nb 3 Sn accelerator dipole magnet are presented. Finally, the possible use of this system as a quench localization system is proposed

  6. Systems Measures of Water Distribution System Resilience

    Energy Technology Data Exchange (ETDEWEB)

    Klise, Katherine A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Murray, Regan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Walker, La Tonya Nicole [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-01-01

    Resilience is a concept that is being used increasingly to refer to the capacity of infrastructure systems to be prepared for and able to respond effectively and rapidly to hazardous events. In Section 2 of this report, drinking water hazards, resilience literature, and available resilience tools are presented. Broader definitions, attributes and methods for measuring resilience are presented in Section 3. In Section 4, quantitative systems performance measures for water distribution systems are presented. Finally, in Section 5, the performance measures and their relevance to measuring the resilience of water systems to hazards is discussed along with needed improvements to water distribution system modeling tools.

  7. Influence of fluctuating strain on exciton reflection spectra

    DEFF Research Database (Denmark)

    Skettrup, Torben

    1982-01-01

    The influence of an internal distribution of strain on the exciton reflection spectra is investigated. The resulting fluctuating optical constants give rise to a fluctuating phase of reflectivity. The standard deviation σ of these phase fluctuations is the quantity which can be observed...... to derive the dependence of the phase of reflectivity on the direction of the fluctuating optical axis. The results obtained for σ are compared with the experimental depolarization spectra of ZnO. The only fitting parameter is the common standard deviation of the strain components. It is found......, for example, between crossed polarizers or from ellipsometric measurements. Assuming the phase fluctuations to obey a Gaussian distribution, σ can be expressed in a simple way in terms of the degree of polarization or the depolarization of the reflected light. σ is then derived in terms of the standard...

  8. Thermal Expansion and Magnetostriction Measurements at Cryogenic Temperature Using the Strain Gauge Method.

    Science.gov (United States)

    Wang, Wei; Liu, Huiming; Huang, Rongjin; Zhao, Yuqiang; Huang, Chuangjun; Guo, Shibin; Shan, Yi; Li, Laifeng

    2018-01-01

    Thermal expansion and magnetostriction, the strain responses of a material to temperature and a magnetic field, especially properties at low temperature, are extremely useful to study electronic and phononic properties, phase transitions, quantum criticality, and other interesting phenomena in cryogenic engineering and materials science. However, traditional dilatometers cannot provide magnetic field and ultra-low temperature (thermal expansion and magnetostriction at cryogenic temperature using the strain gauge method based on a Physical Properties Measurements System (PPMS). The interfacing software and automation were developed using LabVIEW. The sample temperature range can be tuned continuously between 1.8 and 400 K. With this PPMS-aided measuring system, we can observe temperature and magnetic field dependence of the linear thermal expansion of different solid materials easily and accurately.

  9. Questionnaire on the measurement condition of distribution coefficient

    International Nuclear Information System (INIS)

    Takebe, Shinichi; Kimura, Hideo; Matsuzuru, Hideo

    2001-05-01

    The distribution coefficient is used for various transport models to evaluate the migration behavior of radionuclides in the environment and is very important parameter in environmental impact assessment of nuclear facility. The questionnaire was carried out for the purpose of utilizing for the proposal of the standard measuring method of distribution coefficient. This report is summarized the result of questionnairing on the sampling methods and storage condition, the pretreatment methods, the analysis items in the physical/chemical characteristics of the sample, and the distribution coefficient measuring method and the measurement conditions in the research institutes within country. (author)

  10. Spherical Nanoindentation Stress-Strain Measurements of BOR-60 14YWT-NFA1 Irradiated Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, Jordan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carvajal Nunez, Ursula [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Krumwiede, David [Univ. of California, Berkeley, CA (United States); Saleh, Tarik A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hosemann, Peter [Univ. of California, Berkeley, CA (United States); Nelson, Andrew Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Maloy, Stuart Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mara, Nathan Allan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-28

    Spherical nanoindentation stress-strain protocols were applied to characterize unirradiated and fast neutron irradiated nanostructured ferritic alloy (NFA) 14YWT and compared against Berkovich nanohardness and available tensile data. The predicted uniaxial yield strength from spherical, 100 and 5 micron radii, indentation yield strength measurements was 1100-1400 MPa which compares well with the predictions from Berkovich nanohardness, 1200 MPa, and available tensile data, ~1100 MPa. However, spherical indentation measurements predict an increase in the uniaxial yield strength of ~1 GPa while Berkovich nanohardness measurements predict an increase of only ~250 MPa. No tensile data exists on the irradiated condition. It is believed the difference in the predicted uniaxial yield strength between spherical and Berkovich nanoindentation are due to a low number of tests on the irradiated sample combined with the significant heterogeneity in the microstructure, the differences in sensitivity to sample preparation on the irradiated sample between the two indentation protocols , and/or in how strain localizes under the indenter with the possibility of dislocation channeling under Berkovich hardness indents leading to strain softening. Nanoindentation capabilities to test neutron irradiated samples in a radiological area were realized.

  11. Multiwavelength Raman-fiber-laser-based long-distance remote sensor for simultaneous measurement of strain and temperature.

    Science.gov (United States)

    Han, Young-Geun; Tran, T V A; Kim, Sang-Hyuck; Lee, Sang Bae

    2005-06-01

    We propose a simple and flexible multiwavelength Raman-fiber-laser-based long-distance remote-sensing scheme for simultaneous measurement of strain and temperature by use of fiber Bragg gratings. By combining two uniform fiber Bragg gratings with a tunable chirped fiber grating, we readily achieve simultaneous two-channel sensing probes with a high extinction ratio of more than approximately 50 dB over a 50-km distance. When strain and temperature are applied, lasing wavelength separation and shift occur, respectively, since the two uniform fiber Bragg gratings have identical material composition and different cladding diameters. This allows simultaneous measurement of strain and temperature for long-distance sensing applications of more than 50 km.

  12. Nondestructive measurement for radionuclide concentration distribution in soil column

    International Nuclear Information System (INIS)

    Ogawa, Hiromichi; Ohnuki, Toshihiko; Yamamoto, Tadatoshi; Wadachi, Yoshiki

    1985-01-01

    A nondestructive method has been studied for determining the concentration of radionuclide (Cs-137) distributed in a soil column. The concentration distribution was calculated from the counting rate distribution using the efficiency matrix of a detector. The concentration distribution obtained by this method, with measuring efficiencies of theoretical calculation, coincides well with that obtained by the destructive sampling method. This method is, therefore, found to be effective for the measurement of one dimensional concentration distribution. The measuring limit of this method is affected not only by the radionuclide concentration but also by the shape of concentration distribution in a soil column and also by the way it is divided into concentration blocks. It is found that, the radioactive concentration up to 2.6 x 10 -4 μCi/g (9.62 Bq/g), and also the distribution up to where the concentration reduces to half at every 1 cm of depth, can be measured by this system. The concentration blocks can be divided into 1 cm of thickness as a minimum value. (author)

  13. More plant availability by local and integral strain measurement

    Energy Technology Data Exchange (ETDEWEB)

    Hulshof, H J.M.; Welberg, P G.M. [KEMA Nederland B.V., Arnhem (Netherlands); Bruijn, L.E. de [E.ON Benelux Generation N.V., Rotterdam (Netherlands). Power Plant Maasvlakte

    2002-07-01

    Industrial installations that are under pressure and are operating at high temperatures have a limited life due to creep and fatigue. It is, therefore, of critical importance to know the location of any possible weak spots in the installation. Welds in steam pipes, especially the heat-affected zones in these welds, are such weak spots in the long term. The material deforms and cracks may develop, with significant failure in the worst case. To avoid safety risks, unforeseen plant shutdown and, as a consequence, high costs for unavailability and repair, periodic inspections and strain measurements are recommended. KEMA's SPICA (Speckle Image Correlation Analysis) system is able to measure on-stream (during operation) deformation due to creep in critical areas, like the heat-affected zone in welds. (orig.)

  14. Combined full field stress and strain measurement methods for granular materials

    Directory of Open Access Journals (Sweden)

    Broere W.

    2010-06-01

    Full Text Available The current paper re-introduces the photoelastic measurement method in experimental geomechanics. A full-field phase stepping polariscope suitable for geomechanical model tests has been developed. Additional constraints on the measurement and mechanical setup arising from geomechanical test conditions are outlined as well as the opportunity to measure the displacement fields in the sample with digital image correlation. The capability of the current setup in retrieving the stress and strain field in a granular material is demonstrated.

  15. X-ray study of residual stress distribution of ground ceramics

    International Nuclear Information System (INIS)

    Sakaida, Yoshihisa; Tanaka, Keisuke; Ikuhara, Yuichi; Suzuki, Kenzi.

    1997-01-01

    The residual stress distribution of ground ceramics was determined from the eigen strain existing in the ground surface. The eigen strain of ground ceramics was tensile, and exponentially decreased with the distance from the surface. The residual stress distribution is given as a superposition of an exponential function of compression and a linear function. It is found that the actual residual stress distribution can be approximated by a compressive exponential function because the magnitude of tensile residual stress is negligibly small compared to the compressive residual stress. In the experiments, the diffraction angle was measured on ground silicon nitride for a wide range of sin 2 ψ using the glancing incidence X-ray diffraction technique. A strong nonlinearity was found in the 2θ-sin 2 ψ diagram at very high ψ-angles. From the analysis of nonlinearity, the residual stress distribution was determined. The residual stress distribution of silicon nitride coincided with the distribution calculated from the eigen strain distribution. Transmission electron microscopy was used to clarify the origin of generation of the residual stress. Both strain contrasts and microcracks were observed below the ground surface ; straight dislocations were also observed within silicon nitride grains near the ground surface. (author)

  16. The challenges of measuring in vivo knee collateral ligament strains using ultrasound.

    Science.gov (United States)

    Slane, Laura C; Slane, Josh A; D'hooge, Jan; Scheys, Lennart

    2017-08-16

    Ultrasound-based methods have shown promise in their ability to characterize non-uniform deformations in large energy-storing tendons such as the Achilles and patellar tendons, yet applications to other areas of the body have been largely unexplored. The noninvasive quantification of collateral ligament strain could provide an important clinical metric of knee frontal plane stability, which is relevant in ligament injury and for measuring outcomes following total knee arthroplasty. In this pilot cadaveric experiment, we investigated the possibility of measuring collateral ligament strain with our previously validated speckle-tracking approach, but encountered a number of challenges during both data acquisition and processing. Given the clinical interest in this type of tool, and the fact that this is a developing area of research, the goal of this article is to transparently describe this pilot study, both in terms of methods and results, while also identifying specific challenges to this work and areas for future study. Some challenges faced relate generally to speckle-tracking of soft tissues (e.g. the limitations of using a 2D imaging modality to characterize 3D motion), while others are specific to this application (e.g. the small size and complex anatomy of the collateral ligaments). This work illustrates a clear need for additional studies, particularly relating to the collection of ground-truth data and more thorough validation work. These steps will be critical prior to the translation of ultrasound-based measures of collateral ligament strains into the clinic. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Large-Strain Monitoring Above a Longwall Coal Mine With GPS and Seismic Measurements

    Science.gov (United States)

    Swanson, P. L.; Andreatta, V.; Meertens, C. M.; Krahenbuhl, T.; Kenner, B.

    2001-12-01

    As part of an effort to evaluate continuous GPS measurements for use in mine safety studies, a joint GPS-seismic experiment was conducted at an underground longwall coal mine near Paonia, Colorado in June, 2001. Seismic and deformation signals were measured using prototype low-cost monitoring systems as a longwall panel was excavated 150 m beneath the site. Data from both seismic and GPS instruments were logged onto low-power PC-104 Linux computers which were networked using a wireless LAN. The seismic system under development at NIOSH/SRL is based on multiple distributed 8-channel 24-bit A/D converters. The GPS system uses a serial single-frequency (L1) receiver and UNAVCO's "Jstream" Java data logging software. For this experiment, a continuously operating dual-frequency GPS receiver was installed 2.4 km away to serve as a reference site. In addition to the continuously operating sites, 10 benchmarks were surveyed daily with short "rapid-static" occupations in order to provide greater spatial sampling. Two single-frequency sites were located 35 meters apart on a relatively steep north-facing slope. As mining progressed from the east, net displacements of 1.2 meters to the north and 1.65 meters of subsidence were observed over a period of 6 days. The east component exhibited up to 0.45 meters of eastward displacement (toward the excavation) followed by reverse movement to the west. This cycle, observed approximately two days earlier at the eastern L1 site, is consistent with a change in surface strain from tension to compression as the excavation front passed underneath. As this strain "wave" propagated across the field site, surface deformation underwent a cycle of tension crack nucleation, crack opening (up to 15 cm normal displacements), subsequent crack closure, and production of low-angle-thrust compressional deformation features. Analysis of seismic results, surface deformation, and additional survey results are presented.

  18. Influence of Additive Manufactured Scaffold Architecture on the Distribution of Surface Strains and Fluid Flow Shear Stresses and Expected Osteochondral Cell Differentiation.

    Science.gov (United States)

    Hendrikson, Wim J; Deegan, Anthony J; Yang, Ying; van Blitterswijk, Clemens A; Verdonschot, Nico; Moroni, Lorenzo; Rouwkema, Jeroen

    2017-01-01

    Scaffolds for regenerative medicine applications should instruct cells with the appropriate signals, including biophysical stimuli such as stress and strain, to form the desired tissue. Apart from that, scaffolds, especially for load-bearing applications, should be capable of providing mechanical stability. Since both scaffold strength and stress-strain distributions throughout the scaffold depend on the scaffold's internal architecture, it is important to understand how changes in architecture influence these parameters. In this study, four scaffold designs with different architectures were produced using additive manufacturing. The designs varied in fiber orientation, while fiber diameter, spacing, and layer height remained constant. Based on micro-CT (μCT) scans, finite element models (FEMs) were derived for finite element analysis (FEA) and computational fluid dynamics (CFD). FEA of scaffold compression was validated using μCT scan data of compressed scaffolds. Results of the FEA and CFD showed a significant impact of scaffold architecture on fluid shear stress and mechanical strain distribution. The average fluid shear stress ranged from 3.6 mPa for a 0/90 architecture to 6.8 mPa for a 0/90 offset architecture, and the surface shear strain from 0.0096 for a 0/90 offset architecture to 0.0214 for a 0/90 architecture. This subsequently resulted in variations of the predicted cell differentiation stimulus values on the scaffold surface. Fluid shear stress was mainly influenced by pore shape and size, while mechanical strain distribution depended mainly on the presence or absence of supportive columns in the scaffold architecture. Together, these results corroborate that scaffold architecture can be exploited to design scaffolds with regions that guide specific tissue development under compression and perfusion. In conjunction with optimization of stimulation regimes during bioreactor cultures, scaffold architecture optimization can be used to improve

  19. Evaluation of Pressure Pain Threshold as a Measure of Perceived Stress and High Job Strain

    DEFF Research Database (Denmark)

    Hven, Lisbeth; Frost, Poul; Bonde, Jens Peter Ellekilde

    2017-01-01

    OBJECTIVE: To investigate whether pressure pain threshold (PPT), determined by pressure algometry, can be used as an objective measure of perceived stress and job strain. METHODS: We used cross-sectional base line data collected during 1994 to 1995 within the Project on Research and Intervention...... in Monotonous work (PRIM), which included 3123 employees from a variety of Danish companies. Questionnaire data included 18 items on stress symptoms, 23 items from the Karasek scale on job strain, and information on discomfort in specified anatomical regions was also collected. Clinical examinations included...... pressure pain algometry measurements of PPT on the trapezius and supraspinatus muscles and the tibia. Associations of stress symptoms and job strain with PPT of each site was analyzed for men and women separately with adjustment for age body mass index, and discomfort in the anatomical region closest...

  20. Measurement of fuel importance distribution in non-uniformly distributed fuel systems

    International Nuclear Information System (INIS)

    Yamane, Yoshihiro; Hirano, Yasushi; Yasui, Hazime; Izima, Kazunori; Shiroya, Seiji; Kobayashi, Keiji.

    1995-01-01

    A reactivity effect due to a spatial variation of nuclear fuel concentration is an important problem for nuclear criticality safety in a reprocessing plant. As a theory estimating this reactivity effect, the Goertzel and fuel importance theories are well known. It has been shown that the Goertzel's theory is valid in the range of our experiments based on measurements of reactivity effect and thermal neutron flux in non-uniformly distributed fuel systems. On the other hand, there have been no reports concerning systematic experimental studies on the flatness of fuel importance which is a more general index than the Goertzel's theory. It is derived from the perturbation theory that the fuel importance is proportional to the reactivity change resulting from a change of small amount of fuel mass. Using a uniform and three kinds of nonuniform fuel systems consisting of 93.2% enriched uranium plates and polyethylene plates, the fuel importance distributions were measured. As a result, it was found experimentally that the fuel importance distribution became flat, as its reactivity effect became large. Therefore it was concluded that the flatness of fuel importance distribution is the useful index for estimating reactivity effect of non-uniformly distributed fuel system. (author)

  1. Performance Characteristics and Prediction of Bodyweight using Linear Body Measurements in Four Strains of Broiler Chicken

    OpenAIRE

    I. Udeh; J.O. Isikwenu and G. Ukughere

    2011-01-01

    The objectives of this study were to compare the performance characteristics of four strains of broiler chicken from 2 to 8 weeks of age and predict body weight of the broilers using linear body measurements. The four strains of broiler chicken used were Anak, Arbor Acre, Ross and Marshall. The parameters recorded were bodyweight, weight gain, total feed intake, feed conversion ratio, mortality and some linear body measurements (body length, body width, breast width, drumstick length, shank l...

  2. Maximum stress estimation model for multi-span waler beams with deflections at the supports using average strains.

    Science.gov (United States)

    Park, Sung Woo; Oh, Byung Kwan; Park, Hyo Seon

    2015-03-30

    The safety of a multi-span waler beam subjected simultaneously to a distributed load and deflections at its supports can be secured by limiting the maximum stress of the beam to a specific value to prevent the beam from reaching a limit state for failure or collapse. Despite the fact that the vast majority of accidents on construction sites occur at waler beams in retaining wall systems, no safety monitoring model that can consider deflections at the supports of the beam is available. In this paper, a maximum stress estimation model for a waler beam based on average strains measured from vibrating wire strain gauges (VWSGs), the most frequently used sensors in construction field, is presented. The model is derived by defining the relationship between the maximum stress and the average strains measured from VWSGs. In addition to the maximum stress, support reactions, deflections at supports, and the magnitudes of distributed loads for the beam structure can be identified by the estimation model using the average strains. Using simulation tests on two multi-span beams, the performance of the model is evaluated by estimating maximum stress, deflections at supports, support reactions, and the magnitudes of distributed loads.

  3. Elongational viscosity of narrow molar mass distribution polystyrene

    DEFF Research Database (Denmark)

    Bach, Anders; Almdal, Kristoffer; Rasmussen, Henrik Koblitz

    2003-01-01

    Transient and steady elongational viscosity has been measured for two narrow molar mass distribution polystyrene melts of molar masses 200 000 and 390 000 by means of a filament stretching rheometer. Total Hencky strains of about five have been obtained. The transient elongational viscosity rises...... above the linear viscoelastic prediction at intermediate strains, indicating strain hardening. The steady elongational viscosities are monotone decreasing functions of elongation rate. At elongation rates larger than the inverse reptation time, the steady elongational viscosity scales linearly...

  4. Measurement of subcritical multiplication by the interval distribution method

    International Nuclear Information System (INIS)

    Nelson, G.W.

    1985-01-01

    The prompt decay constant or the subcritical neutron multiplication may be determined by measuring the distribution of the time intervals between successive neutron counts. The distribution data is analyzed by least-squares fitting to a theoretical distribution function derived from a point reactor probability model. Published results of measurements with one- and two-detector systems are discussed. Data collection times are shorter, and statistical errors are smaller the nearer the system is to delayed critical. Several of the measurements indicate that a shorter data collection time and higher accuracy are possible with the interval distribution method than with the Feynman variance method

  5. X-ray measurement of plastic strain by means of Eshelby/Mori-Tanaka model and its application

    International Nuclear Information System (INIS)

    Sasaki, Toshihiko; Lin, Zheng; Hirose, Yukio

    1997-01-01

    A new method is proposed in this paper for determining plastic strains in composite materials using the X-ray diffraction method. The present method was derived by using both Eshelby's approach and the Mori-Tanaka theory to express the stress state in composite materials instead of the elasticity in single-phase materials which is used in the conventional method of X-ray stress measurement. It was found that the plastic strain can be determined from the slope of the linear relation between lattice strains measured by the X-ray diffraction technique and sin 2 ψ using almost the same procedure as that for determining stresses by the conventional X-ray method. The results on ferritic and austenitic dual-phase stainless steel are shown. We discuss the effects of a uniaxial tensile load in a range of plastic deformation on the field of plastic strain as well as on residual macro-, micro- and phase stresses built up in the sample. (author)

  6. Geometry of X-ray based measurement of residual strain at desired penetration depth

    Energy Technology Data Exchange (ETDEWEB)

    Morawiec, A. [Polish Academy of Sciences, Institute of Metallurgy and Materials Science, Krakow (Poland)

    2017-10-15

    X-ray based measurement of residual lattice strains at chosen penetration depth is one of the methods for investigating strain inhomogeneities in near-surface layers of polycrystalline materials. The measurement relies on determining shifts of Bragg peaks for various directions of the scattering vector with respect to the specimen. At each of these directions, to reach a given the penetration depth, a proper specimen orientation is required. The task of determining such orientations, albeit elementary, is quite intricate. The existing literature describes only partial solutions with unspecified domains of application, which fail if applied to beyond the domains. Therefore, geometric aspects of the measurement are analyzed in details. Explicit bounds on measurement parameters are given. The equation fundamental for the procedure is solved with respect to specimen orientations. For a given direction of the scattering vector, there are generally four different specimen orientations leading to the same penetration depth. This simple fact (overlooked in previous analyses) can be used for improving reliability of measurement results. Analytical formulas for goniometer angles representing these orientations are provided. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Progress of a Cross-Correlation Based Optical Strain Measurement Technique for Detecting Radial Growth on a Rotating Disk

    Science.gov (United States)

    Clem, Michelle M.; Abdul-Aziz, Ali; Woike, Mark R.; Fralick, Gustave C.

    2015-01-01

    The modern turbine engine operates in a harsh environment at high speeds and is repeatedly exposed to combined high mechanical and thermal loads. The cumulative effects of these external forces lead to high stresses and strains on the engine components, such as the rotating turbine disks, which may eventually lead to a catastrophic failure if left undetected. The operating environment makes it difficult to use conventional strain gauges, therefore, non-contact strain measurement techniques is of interest to NASA and the turbine engine community. This presentation describes one such approach; the use of cross correlation analysis to measure strain experienced by the engine turbine disk with the goal of assessing potential faults and damage.

  8. Pile Model Tests Using Strain Gauge Technology

    Science.gov (United States)

    Krasiński, Adam; Kusio, Tomasz

    2015-09-01

    Ordinary pile bearing capacity tests are usually carried out to determine the relationship between load and displacement of pile head. The measurement system required in such tests consists of force transducer and three or four displacement gauges. The whole system is installed at the pile head above the ground level. This approach, however, does not give us complete information about the pile-soil interaction. We can only determine the total bearing capacity of the pile, without the knowledge of its distribution into the shaft and base resistances. Much more information can be obtained by carrying out a test of instrumented pile equipped with a system for measuring the distribution of axial force along its core. In the case of pile model tests the use of such measurement is difficult due to small scale of the model. To find a suitable solution for axial force measurement, which could be applied to small scale model piles, we had to take into account the following requirements: - a linear and stable relationship between measured and physical values, - the force measurement accuracy of about 0.1 kN, - the range of measured forces up to 30 kN, - resistance of measuring gauges against aggressive counteraction of concrete mortar and against moisture, - insensitivity to pile bending, - economical factor. These requirements can be fulfilled by strain gauge sensors if an appropriate methodology is used for test preparation (Hoffmann [1]). In this paper, we focus on some aspects of the application of strain gauge sensors for model pile tests. The efficiency of the method is proved on the examples of static load tests carried out on SDP model piles acting as single piles and in a group.

  9. The effect of strain distribution on microstructural developments during forging in a newly developed nickel base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Buckingham, R.C. [Institute of Structural Materials, Swansea University, Bay Campus, Fabian Way, Swansea SA1 8EN (United Kingdom); Argyrakis, C.; Hardy, M.C. [Rolls-Royce plc, PO Box 31, Derby DE24 8BJ (United Kingdom); Birosca, S., E-mail: 522042@swansea.ac.uk [Institute of Structural Materials, Swansea University, Bay Campus, Fabian Way, Swansea SA1 8EN (United Kingdom)

    2016-01-27

    In the current study, the effect of strain distribution in a simple forging geometry on the propensity for recrystallization, and its impact on mechanical properties has been investigated in a newly developed experimental nickel-based superalloy. The new alloy was produced via a Powder Metallurgy (PM) route and was subsequently Hot Isostatic Processed (HIP), isothermally forged, and heat treated to produce a coarse grain microstructure with average grain size of 23–32 μm. The alloy was examined by means of Electron Back-Scatter Diffraction (EBSD) to characterise the microstructural features such as grain orientation and morphology, grain boundary characteristics and the identification of potential Prior Particle Boundaries (PPBs) throughout each stage of the processing route. Results at the central region of the cross-section plane parallel to the loading direction showed significant microstructural differences across the forging depth. This microstructural variation was found to be highly dependent on the value of local strain imparted during forging such that areas of low effective strain showed partial recrystallisation and a necklace grain structure was observed following heat treatment. Meanwhile, a fully recrystallised microstructure with no PPBs was observed in the areas of high strain values, in the central region of the forging.

  10. Multichannel system for angular distribution measurements

    International Nuclear Information System (INIS)

    Burjan, V.; Kroha, V.; Putz, K.

    A description is given of the individual blocks of the spectrometric apparatus used for measuring the angular distribution of particle spectra and excitation functions of (d,p) reactions at an electrostatic accelerator and the U-120 M cyclotron, both operating at the Nuclear Physics Institute of the Czechoslovak Academy of Sciences at Rez. Main attention was devoted to attaining maximum energy resolution at a high measurement efficiency, this by installing 8 independent spectrometric chains allowing simultaneous measurement of angular distribution in 8 points of the beam. The semiconductor detectors were cooled to -40 degC to -60 degC, which significantly reduced the level of inherent detector noise. An energy resolution of 13 keV was attained using Tesla detectors at a particle energy of 11 MeV. A brief review of data processing and software is given. (B.S.)

  11. Thermal expansion measurement of turbine and main steam piping by using strain gages in power plants

    International Nuclear Information System (INIS)

    Na, Sang Soo; Chung, Jae Won; Bong, Suk Kun; Jun, Dong Ki; Kim, Yun Suk

    2000-01-01

    One of the domestic co-generation plants have undergone excessive vibration problems of turbine attributed to external force for years. The root cause of turbine vibration may be shaft alignment problem which sometimes is changed by thermal expansion and external force, even if turbine technicians perfectly performed it. To evaluate the alignment condition from plant start-up to full load, a strain measurement of turbine and main steam piping subjected to thermal loading is monitored by using strain gages. The strain gages are bonded on both bearing housing adjusting bolts and pipe stoppers which installed in the x-direction of left-side main steam piping near the turbine inlet in order to monitor closely the effect of turbine under thermal deformation of turbine casing and main steam piping during plant full load. Also in situ load of constant support hangers in main steam piping system is measured by strain gages and its results are used to rebalance the hanger rod load. Consequently, the experimental stress analysis by using strain gages turns out to be very useful tool to diagnose the trouble and failures of not only to stationary components but to rotating machinery in power plants

  12. Effect of Smart Meter Measurements Data On Distribution State Estimation

    DEFF Research Database (Denmark)

    Pokhrel, Basanta Raj; Nainar, Karthikeyan; Bak-Jensen, Birgitte

    2018-01-01

    Smart distribution grids with renewable energy based generators and demand response resources (DRR) requires accurate state estimators for real time control. Distribution grid state estimators are normally based on accumulated smart meter measurements. However, increase of measurements in the phy......Smart distribution grids with renewable energy based generators and demand response resources (DRR) requires accurate state estimators for real time control. Distribution grid state estimators are normally based on accumulated smart meter measurements. However, increase of measurements...... in the physical grid can enforce significant stress not only on the communication infrastructure but also in the control algorithms. This paper aims to propose a methodology to analyze needed real time smart meter data from low voltage distribution grids and their applicability in distribution state estimation...

  13. Effective X-ray elastic constant measurement for in situ stress measurement of biaxially strained AA5754-O

    International Nuclear Information System (INIS)

    Iadicola, Mark A.; Gnäupel-Herold, Thomas H.

    2012-01-01

    Accurate measurement of stresses by X-ray diffraction requires accurate X-ray elastic constants. Calibration experiments are one method to determine these for a specific material in a specific condition. In this paper, uniaxial tension experiments are used to investigate the variation of these constants after uniaxial and equal-biaxial plastic deformation for an aluminum alloy (AA5754-O) of interest to the automotive industry. These data are critical for accurate measurement of the biaxial mechanical properties of the material using a recent experimental method combining specialized sheet metal forming equipment with portable X-ray diffraction equipment. The measured effective X-ray elastic constants show some minor variation with increased plastic deformation, and this behavior was found to be consistent for both uniaxially and equal-biaxially strained samples. The use of two average values for effective X-ray elastic constants, one in the rolling direction and one transverse to the rolling direction of the sheet material, is shown to be of sufficient accuracy for the combined tests of interest. Comparison of uniaxial data measured using X-ray diffraction and standard methods show good agreement, and biaxial stress–strain results show good repeatability. Additionally, the calibration data show some non-linear behavior, which is analyzed in regards to crystallographic texture and intergranular stress effects. The non-linear behavior is found to be the result of intergranular stresses based on comparison with additional measurements using other X-ray diffraction equipment and neutron diffraction.

  14. Simulation and Experimental Investigations on the Strain Measurement of the Uniform Strength Beam Using a FBG sensor

    International Nuclear Information System (INIS)

    Tu Yumeng; Gong Huaping; Chen Jixuan; Jin Yongxing

    2011-01-01

    The model of force analysis on a uniform strength beam is built by the general finite element program (ANSYS software). The flexivity profile produced by uniform strength beam with different forces is simulated by ANSYS software. In experiment, a fiber Bragg grating sensor is fixed on the uniform strength beam with modified acrylate. The flexivity and strain are varied by changing the load on the end of the beam. The strain of the uniform strength beam is measured with FBG when applied force is varied from 2.45N to14.7N with a step of 2.45N. Both the simulated and experimental results show that, the strain induced by the uniform strength beam is linear with the load force. The sensitivity is 18.32με/N for experimental measurement, and 19.72με/N for simulation. The experimental results are consistent with the simulation results, with the maximum measurement error of strain being 7.4%. It indicates that, the FBG sensor fixed with modified acrylate is proved to be effectively and reliably in the applications of civil engineering.

  15. Genome analysis of Mycoplasma synoviae strain MS-H, the most common M. synoviae strain with a worldwide distribution.

    Science.gov (United States)

    Zhu, Ling; Shahid, Muhammad A; Markham, John; Browning, Glenn F; Noormohammadi, Amir H; Marenda, Marc S

    2018-02-02

    The bacterial pathogen Mycoplasma synoviae can cause subclinical respiratory disease, synovitis, airsacculitis and reproductive tract disease in poultry and is a major cause of economic loss worldwide. The M. synoviae strain MS-H was developed by chemical mutagenesis of an Australian isolate and has been used as a live attenuated vaccine in many countries over the past two decades. As a result it may now be the most prevalent strain of M. synoviae globally. Differentiation of the MS-H vaccine from local field strains is important for epidemiological investigations and is often required for registration of the vaccine. The complete genomic sequence of the MS-H strain was determined using a combination of Illumina and Nanopore methods and compared to WVU-1853, the M. synoviae type strain isolated in the USA 30 years before the parent strain of MS-H, and MS53, a more recent isolate from Brazil. The vaccine strain genome had a slightly larger number of pseudogenes than the two other strains and contained a unique 55 kb chromosomal inversion partially affecting a putative genomic island. Variations in gene content were also noted, including a deoxyribose-phosphate aldolase (deoC) fragment and an ATP-dependent DNA helicase gene found only in MS-H. Some of these sequences may have been acquired horizontally from other avian mycoplasma species. MS-H was somewhat more similar to WVU-1853 than to MS53. The genome sequence of MS-H will enable identification of vaccine-specific genetic markers for use as diagnostic and epidemiological tools to better control M. synoviae.

  16. Cutting force measurement of electrical jigsaw by strain gauges

    International Nuclear Information System (INIS)

    Kazup, L; Varadine Szarka, A

    2016-01-01

    This paper describes a measuring method based on strain gauges for accurate specification of electric jigsaw's cutting force. The goal of the measurement is to provide an overall perspective about generated forces in a jigsaw's gearbox during a cutting period. The lifetime of the tool is affected by these forces primarily. This analysis is part of the research and development project aiming to develop a special linear magnetic brake for realizing automatic lifetime tests of electric jigsaws or similar handheld tools. The accurate specification of cutting force facilitates to define realistic test cycles during the automatic lifetime test. The accuracy and precision resulted by the well described cutting force characteristic and the possibility of automation provide new dimension for lifetime testing of the handheld tools with alternating movement. (paper)

  17. Measurement of the temperature distribution inside the power cable using distributed temperature system

    Science.gov (United States)

    Jaros, Jakub; Liner, Andrej; Papes, Martin; Vasinek, Vladimir; Mach, Veleslav; Hruby, David; Kajnar, Tomas; Perecar, Frantisek

    2015-01-01

    Nowadays, the power cables are manufactured to fulfill the following condition - the highest allowable temperature of the cable during normal operation and the maximum allowable temperature at short circuit conditions cannot exceed the condition of the maximum allowable internal temperature. The distribution of the electric current through the conductor leads to the increase of the amplitude of electrons in the crystal lattice of the cables material. The consequence of this phenomenon is the increase of friction and the increase of collisions between particles inside the material, which causes the temperature increase of the carrying elements. The temperature increase is unwanted phenomena, because it is causing losses. In extreme cases, the long-term overload leads to the cable damaging or fire. This paper deals with the temperature distribution measurement inside the power cables using distributed temperature system. With cooperation with Kabex company, the tube containing optical fibers was installed into the center of power cables. These fibers, except telecommunications purposes, can be also used as sensors in measurements carrying out with distributed temperature system. These systems use the optical fiber as a sensor and allow the continual measurement of the temperature along the whole cable in real time with spatial resolution 1 m. DTS systems are successfully deployed in temperature measurement applications in industry areas yet. These areas include construction, drainage, hot water etc. Their advantages are low cost, resistance to electromagnetic radiation and the possibility of real time monitoring at the distance of 8 km. The location of the optical fiber in the center of the power cable allows the measurement of internal distribution of the temperature during overloading the cable. This measurement method can be also used for prediction of short-circuit and its exact location.

  18. Psychosocial Job Strain and Sleep Quality Interaction Leading to Insufficient Recovery

    OpenAIRE

    Rydstedt, Leif W.; Devereux, Jason J.

    2013-01-01

    The purpose of the study was to assess the impact of job strain and sleep quality on the diurnal pattern of cortisol reactivity, measured by awakening and evening (10 PM) saliva cortisol. The sample consisted of 76 British white-collar workers (24 women, 52 men; mean age 45.8 years). Sleep quality and job strain were assessed in a survey distributed just before the cortisol sampling. Both input variables were dichotomized about the median and factorial ANOVA was used for the statistical analy...

  19. Additive non-uniform random sampling in superimposed fiber Bragg grating strain gauge

    Science.gov (United States)

    Ma, Y. C.; Liu, H. Y.; Yan, S. B.; Yang, Y. H.; Yang, M. W.; Li, J. M.; Tang, J.

    2013-05-01

    This paper demonstrates an additive non-uniform random sampling and interrogation method for dynamic and/or static strain gauge using a reflection spectrum from two superimposed fiber Bragg gratings (FBGs). The superimposed FBGs are designed to generate non-equidistant space of a sensing pulse train in the time domain during dynamic strain gauge. By combining centroid finding with smooth filtering methods, both the interrogation speed and accuracy are improved. A 1.9 kHz dynamic strain is measured by generating an additive non-uniform randomly distributed 2 kHz optical sensing pulse train from a mean 500 Hz triangular periodically changing scanning frequency.

  20. Pseudomagnetic fields and triaxial strain in graphene

    DEFF Research Database (Denmark)

    Settnes, Mikkel; Power, Stephen; Jauho, Antti-Pekka

    2016-01-01

    Pseudomagnetic fields, which can result from nonuniform strain distributions, have received much attention in graphene systems due to the possibility of mimicking real magnetic fields with magnitudes of greater than 100 T. We examine systems with such strains confined to finite regions ("pseudoma......Pseudomagnetic fields, which can result from nonuniform strain distributions, have received much attention in graphene systems due to the possibility of mimicking real magnetic fields with magnitudes of greater than 100 T. We examine systems with such strains confined to finite regions......-binding calculations of single pseudomagnetic dots in extended graphene sheets confirm these predictions, and are also used to study the effect of rotating the strain direction with respect to the underlying graphene lattice, and varying the size of the pseudomagnetic dot....

  1. Thermal Expansion and Magnetostriction Measurements at Cryogenic Temperature Using the Strain Gauge Method

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2018-03-01

    Full Text Available Thermal expansion and magnetostriction, the strain responses of a material to temperature and a magnetic field, especially properties at low temperature, are extremely useful to study electronic and phononic properties, phase transitions, quantum criticality, and other interesting phenomena in cryogenic engineering and materials science. However, traditional dilatometers cannot provide magnetic field and ultra-low temperature (<77 K environment easily. This paper describes the design and test results of thermal expansion and magnetostriction at cryogenic temperature using the strain gauge method based on a Physical Properties Measurements System (PPMS. The interfacing software and automation were developed using LabVIEW. The sample temperature range can be tuned continuously between 1.8 and 400 K. With this PPMS-aided measuring system, we can observe temperature and magnetic field dependence of the linear thermal expansion of different solid materials easily and accurately.

  2. Thermal expansion and magnetostriction measurements at cryogenic temperature using the strain gage method

    Science.gov (United States)

    Wang, Wei; Liu, Huiming; Huang, Rongjin; Zhao, Yuqiang; Huang, Chuangjun; Guo, Shibin; Shan, Yi; Li, Laifeng

    2018-03-01

    Thermal expansion and magnetostriction, the strain responses of a material to temperature and a magnetic field, especially properties at low temperature, are extremely useful to study electronic and phononic properties, phase transitions, quantum criticality, and other interesting phenomena in cryogenic engineering and materials science. However, traditional dilatometers cannot provide magnetic field and ultra low temperature (<77 K) environment easily. This paper describes the design and test results of thermal expansion and magnetostriction at cryogenic temperature using the strain gage method based on a Physical Properties Measurements System (PPMS). The interfacing software and automation were developed using LabVIEW. The sample temperature range can be tuned continuously between 1.8 K and 400 K. With this PPMS-aided measuring system, we can observe temperature and magnetic field dependence of the linear thermal expansion of different solid materials easily and accurately.

  3. Large-strain optical fiber sensing and real-time FEM updating of steel structures under the high temperature effect

    International Nuclear Information System (INIS)

    Huang, Ying; Fang, Xia; Xiao, Hai; Bevans, Wesley James; Chen, Genda; Zhou, Zhi

    2013-01-01

    Steel buildings are subjected to fire hazards during or immediately after a major earthquake. Under combined gravity and thermal loads, they have non-uniformly distributed stiffness and strength, and thus collapse progressively with large deformation. In this study, large-strain optical fiber sensors for high temperature applications and a temperature-dependent finite element model updating method are proposed for accurate prediction of structural behavior in real time. The optical fiber sensors can measure strains up to 10% at approximately 700 °C. Their measurements are in good agreement with those from strain gauges up to 0.5%. In comparison with the experimental results, the proposed model updating method can reduce the predicted strain errors from over 75% to below 20% at 800 °C. The minimum number of sensors in a fire zone that can properly characterize the vertical temperature distribution of heated air due to the gravity effect should be included in the proposed model updating scheme to achieve a predetermined simulation accuracy. (paper)

  4. Strain measurement of abdominal aortic aneurysm with real-time 3D ultrasound speckle tracking.

    Science.gov (United States)

    Bihari, P; Shelke, A; Nwe, T H; Mularczyk, M; Nelson, K; Schmandra, T; Knez, P; Schmitz-Rixen, T

    2013-04-01

    Abdominal aortic aneurysm rupture is caused by mechanical vascular tissue failure. Although mechanical properties within the aneurysm vary, currently available ultrasound methods assess only one cross-sectional segment of the aorta. This study aims to establish real-time 3-dimensional (3D) speckle tracking ultrasound to explore local displacement and strain parameters of the whole abdominal aortic aneurysm. Validation was performed on a silicone aneurysm model, perfused in a pulsatile artificial circulatory system. Wall motion of the silicone model was measured simultaneously with a commercial real-time 3D speckle tracking ultrasound system and either with laser-scan micrometry or with video photogrammetry. After validation, 3D ultrasound data were collected from abdominal aortic aneurysms of five patients and displacement and strain parameters were analysed. Displacement parameters measured in vitro by 3D ultrasound and laser scan micrometer or video analysis were significantly correlated at pulse pressures between 40 and 80 mmHg. Strong local differences in displacement and strain were identified within the aortic aneurysms of patients. Local wall strain of the whole abdominal aortic aneurysm can be analysed in vivo with real-time 3D ultrasound speckle tracking imaging, offering the prospect of individual non-invasive rupture risk analysis of abdominal aortic aneurysms. Copyright © 2013 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

  5. Growth, delayed fluorescence and pigment composition of four Prorocentrum minimum strains growing at two salinities

    Directory of Open Access Journals (Sweden)

    MAJA BERDEN-ZRIMEC

    2008-01-01

    Full Text Available Prorocentrum minimum is a potentially harmful and widely distributed marine dinoflagellate. Several P. minimum strains have already been studied, showing phylogenetical relations of strains isolated from the same geographical regions. Similarity among the strains was further examined on the basis of their physiology. Pigment composition and concentration, as well as delayed fluorescence (DF decay kinetics and intensity, were measured in four P. minimum strains isolated from the Baltic and Adriatic Seas. The strains were grown at two salinities characteristic of the Baltic (8 PSU and North Adriatic Seas (32 PSU. Strain differences in DF decay kinetics and growth did not always follow their genetic relations. While two strains showed similarities to the previously described strains from the Baltic and Adriatic Seas in DF parameters, the other two strains seemed to be specific. The differences among strains isolated from the same sea could stem from adaptations to conditions in the specific habitats. Cluster analysis based on the ratio of individual carotenoid pigments concentrations to the chlorophyll a concentration or to total carotenoids were not conclusive in showing relations among the strains. Among the measured pigments, only peridinin concentration depended on salinity in all st

  6. Spatial distribution measured by the modulation transfer function

    International Nuclear Information System (INIS)

    Rossi, P.; Brice, D.K.; Doyle, B.L.

    2003-01-01

    Spatial distributions in ion micro-beam and IBA experimental practice are regularly characterized through the parameters of FWHM and tail area percentage (TF, tail fraction). Linear and stationary transducer theory allows these distributions to be described in the Fourier-dual frequency space, and provides an indirect method to evaluate them through measurement of the modulation transfer function (MTF). We suggest direct measurement of MTF by employing bar pattern grids, similar to those used for calibration of radiological equipment. Assuming spatial distributions of the form exp(-(|αx|) η ), we are able to relate the MTF measurements to the more popular FWHM and TF. This new approach to determine spatial resolution can become a standard for use by the micro-beam community

  7. Phantoms for IMRT dose distribution measurement and treatment verification

    International Nuclear Information System (INIS)

    Low, Daniel A.; Gerber, Russell L.; Mutic, Sasa; Purdy, James A.

    1998-01-01

    Background: The verification of intensity-modulated radiation therapy (IMRT) patient treatment dose distributions is currently based on custom-built or modified dose measurement phantoms. The only commercially available IMRT treatment planning and delivery system (Peacock, NOMOS Corp.) is supplied with a film phantom that allows accurate spatial localization of the dose distribution using radiographic film. However, measurements using other dosimeters are necessary for the thorough verification of IMRT. Methods: We have developed a phantom to enable dose measurements using a cylindrical ionization chamber and the localization of prescription isodose curves using a matrix of thermoluminescent dosimetry (TLD) chips. The external phantom cross-section is identical to that of the commercial phantom, to allow direct comparisons of measurements. A supplementary phantom has been fabricated to verify the IMRT dose distributions for pelvis treatments. Results: To date, this phantom has been used for the verification of IMRT dose distributions for head and neck and prostate cancer treatments. Designs are also presented for a phantom insert to be used with polymerizing gels (e.g., BANG-2) to obtain volumetric dose distribution measurements. Conclusion: The phantoms have proven useful in the quantitative evaluation of IMRT treatments

  8. Measurement for cobalt target activity and its axial distribution

    International Nuclear Information System (INIS)

    Li Xingyuan; Chen Zigen.

    1985-01-01

    Cobalt target activity and its axial distribution are measured in process of producing radioactive isotopes 60 Co by irradiation in HFETR. Cobalt target activity is obtained with measured data at 3.60 m and 4.60 m, relative axial distribution of cobalt target activity is obtained with one at 30 cm, and axial distribution of cobalt target activity(or specific activity) is obtained with both of data. The difference between this specific activity and measured result for 60 Co teletherapy sources in the end is less than +- 5%

  9. Strain Measurement of Steel Roof Truss Using FBG Sensor during Construction of Reverse Shell Shaped Reinforced Concrete Structure

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kun Woo [Kyungpook National University, Daegu (Korea, Republic of); Rhim, Hong Chul; Seo, Tae Seok [Yonsei University, Seoul (Korea, Republic of)

    2011-08-15

    Application of FBG (Fiber Bragg Grating) sensors to measure strain of steel roof trusses has been performed. This is to check and confirm the structural integrity of an unusually shaped, reverse shell structure made of reinforced concrete. The issue was to place sensors at proper location and compare the measured values to the results from structural analysis. It has been learned that a deliberate measurement scheme is needed in order to monitor a complex structure during construction. In this study, the measured values were within allowable range of strain, thus confirming the safety of the structure during measurement and construction.

  10. MEASUREMENT OPTIMALIZATION OF ZAKAT DISTRIBUTION AT LEMBAGA AMIL ZAKAT USING VARIABLE MEASUREMENT OF ECONOMY

    Directory of Open Access Journals (Sweden)

    Marissa Haque

    2016-09-01

    Full Text Available The aim of this research conducted is to optimalize the zakat distribution using economy variabel measurement. Design/Metodology. The Quantitative Research Method is used to analyze financial data, with Optimalize Model as Z variable design, Measurement of Economy as Y variable and Objective Output as X variable, using AMOS program and SEM as tool analysis to confirm that the model can be used as a measurement tool. Research result. Using some indicators to analyze every variable, obtaining output and objective result, influence optimalization of measurement of economy. Conclusion. The measurement of optimalization of zakat distribution using measurement of economy variable, with independent variable/output exogenous and objective, can be used as a model to measure Lembaga Amil Zakat performance. Furthermore, this research need to have some indicators’ development especially in the area of objective variable. Key words:   Output, Objective, Measurement of Economy, Distribution Optimalization, Zakat JEL Classification: D64

  11. Strain measurement of objects subjected to aerodynamic heating using digital image correlation: experimental design and preliminary results.

    Science.gov (United States)

    Pan, Bing; Jiang, Tianyun; Wu, Dafang

    2014-11-01

    In thermomechanical testing of hypersonic materials and structures, direct observation and quantitative strain measurement of the front surface of a test specimen directly exposed to severe aerodynamic heating has been considered as a very challenging task. In this work, a novel quartz infrared heating device with an observation window is designed to reproduce the transient thermal environment experienced by hypersonic vehicles. The specially designed experimental system allows the capture of test article's surface images at various temperatures using an optical system outfitted with a bandpass filter. The captured images are post-processed by digital image correlation to extract full-field thermal deformation. To verify the viability and accuracy of the established system, thermal strains of a chromiumnickel austenite stainless steel sample heated from room temperature up to 600 °C were determined. The preliminary results indicate that the air disturbance between the camera and the specimen due to heat haze induces apparent distortions in the recorded images and large errors in the measured strains, but the average values of the measured strains are accurate enough. Limitations and further improvements of the proposed technique are discussed.

  12. Size distribution measurements and chemical analysis of aerosol components

    Energy Technology Data Exchange (ETDEWEB)

    Pakkanen, T.A.

    1995-12-31

    The principal aims of this work were to improve the existing methods for size distribution measurements and to draw conclusions about atmospheric and in-stack aerosol chemistry and physics by utilizing size distributions of various aerosol components measured. A sample dissolution with dilute nitric acid in an ultrasonic bath and subsequent graphite furnace atomic absorption spectrometric analysis was found to result in low blank values and good recoveries for several elements in atmospheric fine particle size fractions below 2 {mu}m of equivalent aerodynamic particle diameter (EAD). Furthermore, it turned out that a substantial amount of analyses associated with insoluble material could be recovered since suspensions were formed. The size distribution measurements of in-stack combustion aerosols indicated two modal size distributions for most components measured. The existence of the fine particle mode suggests that a substantial fraction of such elements with two modal size distributions may vaporize and nucleate during the combustion process. In southern Norway, size distributions of atmospheric aerosol components usually exhibited one or two fine particle modes and one or two coarse particle modes. Atmospheric relative humidity values higher than 80% resulted in significant increase of the mass median diameters of the droplet mode. Important local and/or regional sources of As, Br, I, K, Mn, Pb, Sb, Si and Zn were found to exist in southern Norway. The existence of these sources was reflected in the corresponding size distributions determined, and was utilized in the development of a source identification method based on size distribution data. On the Finnish south coast, atmospheric coarse particle nitrate was found to be formed mostly through an atmospheric reaction of nitric acid with existing coarse particle sea salt but reactions and/or adsorption of nitric acid with soil derived particles also occurred. Chloride was depleted when acidic species reacted

  13. Pulmonary blood flow distribution measured by radionuclide computed tomography

    International Nuclear Information System (INIS)

    Maeda, H.; Itoh, H.; Ishii, Y.

    1982-01-01

    Distributions of pulmonary blood flow per unit lung volume were measured in sitting patients with a radionuclide computed tomography (RCT) by intravenously administered Tc-99m macroaggregates of human serum albumin (MAA). Four different types of distribution were distinguished, among which a group referred as type 2 had a three zonal blood flow distribution as previously reported (West and co-workers, 1964). The pulmonary arterial pressure (Pa) and the venous pressure (Pv) were determined in this group of distribution. These values showed satifactory agreements with the pulmonary artery pressure (Par) and the capillary wedged pressure (Pcw) measured by Swan-Ganz catheter in eighteen supine patients. Those good correlations enable to establish a noninvasive methodology for measurement of pulmonary vascular pressures

  14. Advances in structural damage assessment using strain measurements and invariant shape descriptors

    Science.gov (United States)

    Patki, Amol Suhas

    to the area surrounding the damage, while damage in orthotropic materials tends to have more global repercussions. This calls for analysis of full-field strain distributions adding to the complexity of post-damage life estimation. This study explores shape descriptors used in the field of medical imagery, military targeting and biometric recognition for obtaining a qualitative and quantitative comparison between full-field strain data recorded from damaged composite panels using sophisticated experimental techniques. These descriptors are capable of decomposing images with 103 to 106 pixels into a feature vector with only a few hundred elements. This ability of shape descriptors to achieve enormous reduction in strain data, while providing unique representation, makes them a practical choice for the purpose of structural damage assessment. Consequently, it is relatively easy to statistically compare the shape descriptors of the full-field strain maps using similarity measures rather than the strain maps themselves. However, the wide range of geometric and design features in engineering components pose difficulties in the application of traditional shape description techniques. Thus a new shape descriptor is developed which is applicable to a wide range of specimen geometries. This work also illustrates how shape description techniques can be applied to full-field finite element model validations and updating.

  15. Maximum Stress Estimation Model for Multi-Span Waler Beams with Deflections at the Supports Using Average Strains

    Directory of Open Access Journals (Sweden)

    Sung Woo Park

    2015-03-01

    Full Text Available The safety of a multi-span waler beam subjected simultaneously to a distributed load and deflections at its supports can be secured by limiting the maximum stress of the beam to a specific value to prevent the beam from reaching a limit state for failure or collapse. Despite the fact that the vast majority of accidents on construction sites occur at waler beams in retaining wall systems, no safety monitoring model that can consider deflections at the supports of the beam is available. In this paper, a maximum stress estimation model for a waler beam based on average strains measured from vibrating wire strain gauges (VWSGs, the most frequently used sensors in construction field, is presented. The model is derived by defining the relationship between the maximum stress and the average strains measured from VWSGs. In addition to the maximum stress, support reactions, deflections at supports, and the magnitudes of distributed loads for the beam structure can be identified by the estimation model using the average strains. Using simulation tests on two multi-span beams, the performance of the model is evaluated by estimating maximum stress, deflections at supports, support reactions, and the magnitudes of distributed loads.

  16. Evaluation of the dynamic behavior of a Pelton runner based on strain gauge measurements

    Science.gov (United States)

    Mack, Reiner; Probst, Christian

    2016-11-01

    A reliable mechanical design of Pelton runners is very important in the layout of new installations and modernizations. Especially in horizontal machines, where the housing is not embedded into concrete, a rupture of a runner bucket can have severe consequences. Even if a crack in the runner is detected on time, the outage time that follows the malfunction of the runner is shortening the return of investment. It is a fact that stresses caused by the runner rotation and the jet forces are superposed by high frequent dynamic stresses. In case of resonance it even can be the dominating effect that is limiting the lifetime of a runner. Therefore a clear understanding of the dynamic mechanisms is essential for a safe runner design. This paper describes the evaluation of the dynamic behavior of a Pelton runner installed in a model turbine based on strain gauge measurements. Equipped with strain gauges at the root area of the buckets, the time responses of the strains under the influence of various operational parameters were measured. As a result basic theories for the jet bucket excitation were verified and the influence of the water mass was detected by evaluating the frequency shift in case of resonance. Furthermore, the influence of the individual bucket masses onto the dynamic behaviour for different mode shapes got measured.

  17. Clay behaviour under thermal gradients elastic and plastic strains

    International Nuclear Information System (INIS)

    Pintado, Xavier; Autio, Jorma; Punkkinen, Olli

    2010-01-01

    Document available in extended abstract form only. The nuclear waste repositories will generate strong temperature gradients at the clay barrier. The heat and water transport generate volume change in the clay. An experimental work is proposed here. The clay reference is the MX-80. The test device imposes a fixed heat flow in one side of the sample and maintains constant the temperature on the other side. Two samples are tested for symmetry. The samples are unconfined and the total mass of water remains constant. This situation creates a strong thermal gradient in the samples. The final radial strains in some places of the sample, the total vertical strain and the water content distribution will be measured just at the end of the test and some weeks later in order to distinguish the elastic strains from the plastic strains. The test period mustn't be longer than two weeks because a large quantity of water loses through the rubber membrane and the heads of the sample. The maximum temperature reached in the cooper is 90 degrees because with higher temperature, the rubber membrane is damaged. This test is already simulated by a numerical code. Thermal, thermo-hydraulic and thermo-hydro-mechanical analyses are being done. These analyses allow studying the different fluxes inside the sample and its quantification. Water content distribution is compared with the water content calculated from the reference parameters in the clay. The water distribution and the change of diameter after the test will also be studied. This experimental work will allow to know what is the percentage of the strains elastic or plastic and check the mechanical model. The experimental diameter change is compared with the diameter change calculated from the reference parameters of the clay. (authors)

  18. Micromechanical modelling of the cyclic stress-strain behaviour of nickel polycrystals

    International Nuclear Information System (INIS)

    Steckmeyer, A.; Sauzay, M.; Weidner, A.; Hieckmann, E.

    2012-01-01

    A crystalline elasto-plasticity model is proposed to describe the cyclic behaviour of face-centred cubic crystals. It is based on many experimental observations correlating the observed dislocation structures with the orientations of corresponding crystals. The model distinguishes between two families of crystals. The first family gathers crystals for which the tension-compression loading axis is located in the centre of the standard stereo-graphic triangle. These crystals, in which bundle and/or slip band dislocation structures are usually observed, are subjected to single slip deformation. The second family gathers crystals in which labyrinths or wall dislocation structures develop. These crystals are subjected to multiple slip deformation. Crystalline plasticity parameters are adjusted using only the single crystal cyclic stress strain curves measured for one orientation of each of the two families. The relevance of the model is evaluated through finite elements calculations of the uniaxial cyclic deformation of texture-free nickel polycrystals at room temperature. The macroscopic predictions are in reasonable agreement with experimental data concerning both the cyclic stress-strain curve and the hysteresis loops provided either large grain sizes or intermediate to high plastic strains are considered. By construction, the modelling is unable to predict grain size effect observed at low plastic strain. The distributions of the mean grain plastic strains become narrower as the macroscopic plastic strain amplitude increases, which appears consistent with the large scattering in high-cycle fatigue lifetimes usually observed. On the contrary, the distributions of mean grain axial stresses get broader, in agreement with neutron and X-ray diffraction measurement values published in the literature. The influence of the material parameters is then discussed. Finally, the cumulative probability curves of the number of cycles to fatigue microcrack nucleation are deduced

  19. Measurement of Plastic Stress and Strain for Analytical Method Verification (MSFC Center Director's Discretionary Fund Project No. 93-08)

    Science.gov (United States)

    Price, J. M.; Steeve, B. E.; Swanson, G. R.

    1999-01-01

    The analytical prediction of stress, strain, and fatigue life at locations experiencing local plasticity is full of uncertainties. Much of this uncertainty arises from the material models and their use in the numerical techniques used to solve plasticity problems. Experimental measurements of actual plastic strains would allow the validity of these models and solutions to be tested. This memorandum describes how experimental plastic residual strain measurements were used to verify the results of a thermally induced plastic fatigue failure analysis of a space shuttle main engine fuel pump component.

  20. Reconstruction of core inlet temperature distribution by cold leg temperature measurements

    International Nuclear Information System (INIS)

    Saarinen, S.; Antila, M.

    2010-01-01

    The reduced core of Loviisa NPP contains 33 thermocouple measurements measuring the core inlet temperature. Currently, these thermocouple measurements are not used in determining the inlet temperature distribution. The average of cold leg temperature measurements is used as inlet temperature for each fuel assembly. In practice, the inlet temperature distribution is not constant. Thus, using a constant inlet temperature distribution induces asymmetries in the measured core power distribution. Using a more realistic inlet temperature distribution would help us to reduce virtual asymmetries of the core power distribution and increase the thermal margins of the core. The thermocouples at the inlet cannot be used directly to measure the inlet temperature accurately because the calibration of the thermocouples that is done at hot zero power conditions is no longer valid at full power, when there is temperature change across the core region. This is due to the effect of neutron irradiation on the Seebeck coefficient of the thermocouple wires. Therefore, we investigate in this paper a method to determine the inlet temperature distribution based on the cold leg temperature measurements. With this method we rely on the assumption that although the core inlet thermocouple measurements do not measure the absolute temperature accurately they do measure temperature changes with sufficient accuracy particularly in big disturbances. During the yearly testing of steam generator safety valves we observe a large temperature increase up to 12 degrees in the cold leg temperature. The change in the temperature of one of the cold legs causes a local disturbance in the core inlet temperature distribution. Using the temperature changes observed in the inlet thermocouple measurements we are able to fit six core inlet temperature response functions, one for each cold leg. The value of a function at an assembly inlet is determined only by the corresponding cold leg temperature disturbance

  1. Flux distribution measurements in the Bruce A unit 1 reactor

    International Nuclear Information System (INIS)

    Okazaki, A.; Kettner, D.A.; Mohindra, V.K.

    1977-07-01

    Flux distribution measurements were made by copper wire activation during low power commissioning of the unit 1 reactor of the Bruce A generating station. The distribution was measured along one diameter near the axial and horizontal midplanes of the reactor core. The activity distribution along the copper wire was measured by wire scanners with NaI detectors. The experiments were made for five configurations of reactivity control mechanisms. (author)

  2. A strain gauge

    DEFF Research Database (Denmark)

    2017-01-01

    The invention relates to a strain gauge of a carrier layer and a meandering measurement grid (101) positioned on the carrier layer, wherein the measurement grid comprises a number of measurement grid sections placed side by side with gaps in between, and a number of end loops (106) interconnecting...... relates to a method for manufacturing a strain gauge as mentioned above....

  3. Measurements of translation, rotation and strain: new approaches to seismic processing and inversion

    NARCIS (Netherlands)

    Bernauer, M.; Fichtner, A.; Igel, H.

    2012-01-01

    We propose a novel approach to seismic tomography based on the joint processing of translation, strain and rotation measurements. Our concept is based on the apparent S and P velocities, defined as the ratios of displacement velocity and rotation amplitude, and displacement velocity and

  4. Strain fields around dislocation arrays in a Σ9 silicon bicrystal measured by scanning transmission electron microscopy

    Science.gov (United States)

    Couillard, Martin; Radtke, Guillaume; Botton, Gianluigi A.

    2013-04-01

    Strain fields around grain boundary dislocations are measured by applying geometric phase analysis on atomic resolution images obtained from multiple fast acquisitions in scanning transmission electron microscopy. Maps of lattice distortions in silicon introduced by an array of pure edge dislocations located at a Σ9(122) grain boundary are compared with the predictions from isotropic elastic theory, and the atomic structure of dislocation cores is deduced from images displaying all the atomic columns. For strain measurements, reducing the acquisition time is found to significantly decrease the effects of instabilities on the high-resolution images. Contributions from scanning artefacts are also diminished by summing multiple images following a cross-correlation alignment procedure. Combined with the sub-Ångström resolution obtained with an aberration corrector, and the stable dedicated microscope's environment, therapid acquisition method provides the measurements of atomic displacements with accuracy below 10 pm. Finally, the advantages of combining strain measurements with the collection of various analytical signals in a scanning transmission electron microscope are discussed.

  5. Experimental technologies comparison for strain measurement of a composite main landing gear bay specimen

    Science.gov (United States)

    Viscardi, Massimo; Arena, Maurizio; Ciminello, Monica; Guida, Michele; Meola, Carosena; Cerreta, Pietro

    2018-03-01

    The development of advanced monitoring system for strain measurements on aeronautical components remain an important target both when related to the optimization of the lead-time and cost for part validation, allowing earlier entry into service, and when related to the implementation of advanced health monitoring systems dedicated to the in-service parameters verification and early stage detection of structural problems. The paper deals with the experimental testing of a composite samples set of the main landing gear bay for a CS-25 category aircraft, realized through an innovative design and production process. The test have represented a good opportunity for direct comparison of different strain measurement techniques: Strain Gauges (SG) and Fibers Bragg Grating (FBG) have been used as well as non-contact techniques, specifically the Digital Image Correlation (DIC) and Infrared (IR) thermography applied where possible in order to highlight possible hot-spot during the tests. The crucial points identification on the specimens has been supported by means of advanced finite element simulations, aimed to assessment of the structural strength and deformation as well as to ensure the best performance and the global safety of the whole experimental campaign.

  6. Reliability and Inequality Measures for the Weimal Distribution ...

    African Journals Online (AJOL)

    ). This article aimed at discussing both reliability and inequality measures from the Weimal distribution. The work has derived and discussed theoretically, expressions for the survival and hazard function of the Weimal distribution. The ordinary ...

  7. Field Strain Measurement on the Fiber-Epoxy Scale in CFRPs

    KAUST Repository

    Tao, Ran

    2015-06-08

    Laminated composites are materials with complex architecture made of continuous fibers (usually glass or carbon) embedded within a polymeric resin. The properties of the raw materials can vary from one point to another due to different local processing conditions or complex geometrical features for example. A first step towards the identification of these spatially varying material parameters is to image with precision the displacement fields in this complex microstructure when subjected to mechanical loading. Secondary electron images obtained by scanning electron microscopy (SEM) and then numerically deformed are post-processed by either local subset-based digital image correlation (DIC) or global finite-element based DIC to measure the displacement and strain fields at the fiber-matrix scale in a cross-ply composite. It is shown that when global DIC is applied with a conformal mesh, it can capture more accurate local variations in the strain fields as it takes into account the underlying microstructure. In comparison to subset DIC, global DIC is better suited for capturing gradients across the fiber-matrix interfaces.

  8. Grain orientation and strain measurements in sub-micron wide passivated individual aluminum test structures

    International Nuclear Information System (INIS)

    Tamura, N.; Valek, B.C.; Spolenak, R.; MacDowell, A.A.; Celestre, R.S.; Padmore, H.A.; Brown, W.L.; Marieb, T.; Bravman, J.C.; Batterman, B.W.; Patel, J.R.

    2001-01-01

    An X-ray microdiffraction dedicated beamline, combining white and monochromatic beam capabilities, has been built at the Advanced Light Source. The purpose of this beamline is to address the myriad of problems in Materials Science and Physics that require submicron x-ray beams for structural characterization. Many such problems are found in the general area of thin films and nano-materials. For instance, the ability to characterize the orientation and strain state in individual grains of thin films allows us to measure structural changes at a very local level. These microstructural changes are influenced heavily by such parameters as deposition conditions and subsequent treatment. The accurate measurement of strain gradients at the micron and sub-micron level finds many applications ranging from the strain state under nano-indenters to gradients at crack tips. Undoubtedly many other applications will unfold in the future as we gain experience with the capabilities and limitations of this instrument. We have applied this technique to measure grain orientation and residual stress in single grains of pure Al interconnect lines and preliminary results on post-electromigration test experiments are presented. It is shown that measurements with this instrument can be used to resolve the complete stress tensor (6 components) in a submicron volume inside a single grain of Al under a passivation layer with an overall precision of about 20 MPa. The microstructure of passivated lines appears to be complex, with grains divided into identifiable subgrains and noticeable local variations of both tensile/compressive and shear stresses within single grains

  9. Additive non-uniform random sampling in superimposed fiber Bragg grating strain gauge

    International Nuclear Information System (INIS)

    Ma, Y C; Liu, H Y; Yan, S B; Li, J M; Tang, J; Yang, Y H; Yang, M W

    2013-01-01

    This paper demonstrates an additive non-uniform random sampling and interrogation method for dynamic and/or static strain gauge using a reflection spectrum from two superimposed fiber Bragg gratings (FBGs). The superimposed FBGs are designed to generate non-equidistant space of a sensing pulse train in the time domain during dynamic strain gauge. By combining centroid finding with smooth filtering methods, both the interrogation speed and accuracy are improved. A 1.9 kHz dynamic strain is measured by generating an additive non-uniform randomly distributed 2 kHz optical sensing pulse train from a mean 500 Hz triangular periodically changing scanning frequency. (paper)

  10. Sensitive element of multifunctional sensor for measuring temperature, strain and magnetic field induction

    Directory of Open Access Journals (Sweden)

    Druzhinin A. A.

    2017-12-01

    Full Text Available Sensitive element of multifunctional sensor for measuring temperature, strain and magnetic field induction has been developed based on the studies of electrical conductivity and magnetoresistance of silicon and germanium microcrystals in the temperature range 4.2—70 K, strain ±1.5*10–3 rel.un. and magnetic fields of 0—14 T. The feature of the sensitive element is the using of the p- and n-type conductivity germanium microcrystals as mechanical and magnetic field sensors, respectively, and the p-type silicon microcrystal — as temperature sensor. That allows providing the compensation of temperature influence on piezoresistance and on sensitivity to the magnetic field.

  11. Combined Synchrotron X-ray Diffraction and Digital Image Correlation Technique for Measurement of Austenite Transformation with Strain in TRIP-assisted Steels

    Energy Technology Data Exchange (ETDEWEB)

    Poling, Whitney A.; Savic, Vesna; Hector, Louis G.; Sachdev, Anil K.; Hu, Xiaohua; Devaraj, Arun; Abu-Farha, Fadi

    2016-04-05

    The strain-induced, diffusionless shear transformation of retained austenite to martensite during straining of transformation induced plasticity (TRIP) assisted steels increases strain hardening and delays necking and fracture leading to exceptional ductility and strength, which are attractive for automotive applications. A novel technique that provides the retained austenite volume fraction variation with strain in TRIP-assisted steels with improved precision is presented. Digital images of the gauge section of tensile specimens were first recorded up to selected plastic strains with a stereo digital image correlation (DIC) system. The austenite volume fraction was measured by synchrotron X-ray diffraction from small squares cut from the gage section. Strain fields in the squares were then computed by localizing the strain measurement to the corresponding region of a given square during DIC post-processing of the images recorded during tensile testing. Results obtained for a QP980 steel are used to study the influence of initial volume fraction of austenite and the austenite transformation with strain on tensile mechanical behavior.

  12. Distribution measurement of 60Co target radioactive specific activity

    International Nuclear Information System (INIS)

    Li Xingyan; Chen Zigen; Ren Min

    1994-01-01

    Radioactive specific activity distribution of cobalt 60 target by irradiation in HFETR is a key parameter. With the collimate principle, the under water measurement device and conversion coefficient which is get by experiments, and the radioactive specific activity distribution is obtained. The uncertainty of measurement is less than 10%

  13. Unified Hall-Petch description of nano-grain nickel hardness, flow stress and strain rate sensitivity measurements

    Science.gov (United States)

    Armstrong, R. W.; Balasubramanian, N.

    2017-08-01

    It is shown that: (i) nano-grain nickel flow stress and hardness data at ambient temperature follow a Hall-Petch (H-P) relation over a wide range of grain size; and (ii) accompanying flow stress and strain rate sensitivity measurements follow an analogous H-P relationship for the reciprocal "activation volume", (1/v*) = (1/A*b) where A* is activation area. Higher temperature flow stress measurements show a greater than expected reduction both in the H-P kɛ and in v*. The results are connected with smaller nano-grain size (tested at very low imposed strain rates.

  14. Three-dimensional space charge distribution measurement in electron beam irradiated PMMA

    International Nuclear Information System (INIS)

    Imaizumi, Yoichi; Suzuki, Ken; Tanaka, Yasuhiro; Takada, Tatsuo

    1996-01-01

    The localized space charge distribution in electron beam irradiated PMMA was investigated using pulsed electroacoustic method. Using a conventional space charge measurement system, the distribution only in the depth direction (Z) can be measured assuming the charges distributed uniformly in the horizontal (X-Y) plane. However, it is difficult to measure the distribution of space charge accumulated in small area. Therefore, we have developed the new system to measure the three-dimensional space charge distribution using pulsed electroacoustic method. The system has a small electrode with a diameter of 1mm and a motor-drive X-Y stage to move the sample. Using the data measured at many points, the three-dimensional distribution were obtained. To estimate the system performance, the electron beam irradiated PMMA was used. The electron beam was irradiated from transmission electron microscope (TEM). The depth of injected electron was controlled using the various metal masks. The measurement results were compared with theoretically calculated values of electron range. (author)

  15. Modeling and Experimental Strain Measurements on a Non-Homogeneous Cylinder Under Transverse Load

    National Research Council Canada - National Science Library

    Viator, John A; Kreger, Stephen; Winz, Michele W; Udd, Eric

    2004-01-01

    ...: core, cladding, and stress rods. We measure the strain on a multi-parameter ber Bragg grating written at 1550nm under transverse load at 0, 15, 30, 45, 60, 75, and 90 and compare these values with an analytical solution accounting for internal stresses and transverse load.

  16. Cascaded-cavity Fabry-Perot interferometer for simultaneous measurement of temperature and strain with cross-sensitivity compensation

    Science.gov (United States)

    Tian, Jiajun; Jiao, Yuzhu; Ji, Shaobo; Dong, Xiaolong; Yao, Yong

    2018-04-01

    We propose and demonstrate a fiber sensor for simultaneous temperature and strain measurements. The proposed sensor is implemented by a cascaded-cavity Fabry-Perot (FP) fiber interferometer. The two cascaded FP cavities comprise a micro-air-cavity in a hollow-core tube fiber and a micro-silica-cavity in a standard single-mode fiber. To separate the interference spectrum of each FP cavity, the total spectrum is filtered in the frequency domain through band-pass filters, whose central frequencies were predesigned based on the relationship between the spatial frequency and free spectral range of each FP cavity. The different cross-sectional areas and thermal-optic coefficients of the two FP cavities confer different sensitivities to temperature and strain. Both parameters were measured simultaneously by tracking the wavelength shifts in the filtered interference spectra of the FP cavities. Moreover, the temperature-strain cross-sensitivity was compensated by solving a sensitivity-coefficient matrix equation for the two cavities, using the calibrated temperatures and strains. Other advantages of the proposed sensor are simple fabrication and an all-fiber structure. Owing to these properties, the proposed sensor is potentially applicable to real sensing applications.

  17. Measuring transient high temperature thermal phenomena in hostile environment

    International Nuclear Information System (INIS)

    Brenden, B.B.; Hartman, J.S.; Reich, F.R.

    1980-01-01

    The design of equipment for measuring temperature and strain in a rapidly heated and pressurized cylinder of stainless steel is discussed. Simultaneous cinematography of the full circumference of the cylinder without interference with temperature and strain measurements is also illustrated. The integrated system uses a reflective chamber for the sample and requires careful consideration of the spectral energy distribution utilized by each instrument

  18. Strain distributions in nano-onions with uniform and non-uniform compositions

    International Nuclear Information System (INIS)

    Duan, H L; Karihaloo, B L; Wang, J; Yi, X

    2006-01-01

    Nano-onions are ellipsoidal or spherical particles consisting of a core surrounded by concentric shells of nanometre size. Nano-onions produced by self-assembly and colloidal techniques have different structures and compositions, and thus differ in the state of strains. The mismatch of the thermal expansion coefficients and lattice constants between neighbouring shells induces stress/strain fields in the core and shells, which in turn affect their physical/mechanical properties and/or the properties of the composites containing them. In this paper, the strains in embedded and free-standing nano-onions with uniform and non-uniform compositions are studied in detail. It is found that the strains in the nano-onions can be modified by adjusting their compositions and structures. The results are useful for the band structure engineering of semiconductor nano-onions

  19. Thermographic Analysis of Stress Distribution in Welded Joints

    Directory of Open Access Journals (Sweden)

    Domazet Ž.

    2010-06-01

    Full Text Available The fatigue life prediction of welded joints based on S-N curves in conjunction with nominal stresses generally is not reliable. Stress distribution in welded area affected by geometrical inhomogeneity, irregular welded surface and weld toe radius is quite complex, so the local (structural stress concept is accepted in recent papers. The aim of this paper is to determine the stress distribution in plate type aluminum welded joints, to analyze the reliability of TSA (Thermal Stress Analysis in this kind of investigations, and to obtain numerical values for stress concentration factors for practical use. Stress distribution in aluminum butt and fillet welded joints is determined by using the three different methods: strain gauges measurement, thermal stress analysis and FEM. Obtained results show good agreement - the TSA mutually confirmed the FEM model and stresses measured by strain gauges. According to obtained results, it may be stated that TSA, as a relatively new measurement technique may in the future become a standard tool for the experimental investigation of stress concentration and fatigue in welded joints that can help to develop more accurate numerical tools for fatigue life prediction.

  20. Thermographic Analysis of Stress Distribution in Welded Joints

    Science.gov (United States)

    Piršić, T.; Krstulović Opara, L.; Domazet, Ž.

    2010-06-01

    The fatigue life prediction of welded joints based on S-N curves in conjunction with nominal stresses generally is not reliable. Stress distribution in welded area affected by geometrical inhomogeneity, irregular welded surface and weld toe radius is quite complex, so the local (structural) stress concept is accepted in recent papers. The aim of this paper is to determine the stress distribution in plate type aluminum welded joints, to analyze the reliability of TSA (Thermal Stress Analysis) in this kind of investigations, and to obtain numerical values for stress concentration factors for practical use. Stress distribution in aluminum butt and fillet welded joints is determined by using the three different methods: strain gauges measurement, thermal stress analysis and FEM. Obtained results show good agreement - the TSA mutually confirmed the FEM model and stresses measured by strain gauges. According to obtained results, it may be stated that TSA, as a relatively new measurement technique may in the future become a standard tool for the experimental investigation of stress concentration and fatigue in welded joints that can help to develop more accurate numerical tools for fatigue life prediction.

  1. Arthritis symptoms, the work environment, and the future: measuring perceived job strain among employed persons with arthritis.

    Science.gov (United States)

    Gignac, Monique A M; Sutton, Deborah; Badley, Elizabeth M

    2007-06-15

    To develop a measure of job strain related to differing aspects of working with arthritis and to examine the demographic, illness, work context, and psychosocial variables associated with it. Study participants were 292 employed individuals with osteoarthritis or inflammatory arthritis. Participants were from wave 3 of a 4-wave longitudinal study examining coping and adaptation efforts used to remain employed. Participants completed an interview-administered structured questionnaire, including a Chronic Illness Job Strain Scale (CIJSS) and questions on demographic (e.g., age, sex), illness and disability (e.g., disease type, pain, activity limitations), work context (e.g., job type, job control), and psychosocial variables (e.g., arthritis-work spillover, coworker/managerial support, job perceptions). Principal component analysis and multiple linear regression were used to analyze the data. A single factor solution emerged for the CIJSS. The scale had an internal reliability of 0.95. Greater job strain was reported for future uncertainty, balancing multiple roles, and difficulties accepting the disease than for current workplace conditions. Participants with inflammatory arthritis, more frequent severe pain, greater workplace activity limitations, fewer hours of work, less coworker support, and greater arthritis-work spillover reported greater job strain. The findings underscore the diverse areas that contribute to perceptions of job strain and suggest that existing models of job strain do not adequately capture the stress experienced by individuals working with chronic illnesses or the factors associated with job strain. Measures similar to the CIJSS can enhance the tools researchers and clinicians have available to examine the impact of arthritis in individuals' lives.

  2. Measurement-induced decoherence and Gaussian smoothing of the Wigner distribution function

    International Nuclear Information System (INIS)

    Chun, Yong-Jin; Lee, Hai-Woong

    2003-01-01

    We study the problem of measurement-induced decoherence using the phase-space approach employing the Gaussian-smoothed Wigner distribution function. Our investigation is based on the notion that measurement-induced decoherence is represented by the transition from the Wigner distribution to the Gaussian-smoothed Wigner distribution with the widths of the smoothing function identified as measurement errors. We also compare the smoothed Wigner distribution with the corresponding distribution resulting from the classical analysis. The distributions we computed are the phase-space distributions for simple one-dimensional dynamical systems such as a particle in a square-well potential and a particle moving under the influence of a step potential, and the time-frequency distributions for high-harmonic radiation emitted from an atom irradiated by short, intense laser pulses

  3. Residual strain in the Nb-H system measured by selected area diffraction (SAD)

    International Nuclear Information System (INIS)

    Bulhoes, I.A.M.; Akune, K.; Pinatti, Dyonisio G.

    1981-07-01

    Various specimens of Nb were annealed in vacuum of 10 -3 torr for four hours at 1770 0 K. These speciments were doped with hydrogen up to 1000 ppm by weight and then were analyzed selected area diffraction. The line resolution of the electron channelling pattern was meassured for the specimens with different hydrogen content. These measurements, combined with the measurement of density, permitted one to estimate the residual strain caused by hydrogen. (Author) [pt

  4. A dual 3D DIC-system application for DSL strain and displacement measurements

    DEFF Research Database (Denmark)

    Raurova, I.; Berggreen, Christian; Eriksen, Rasmus Normann Wilken

    2010-01-01

    This paper describes a dual 3D Digital Image Correlation (DIC) system application for DLS strain and displacement measurements, where two 3D DIC-systems are used in parallel. The bonded specimens were tested to failure under monotonic loading in a uni-axial tensile testing machine at ambient...

  5. Psychosocial job strain and sleep quality interaction leading to insufficient recovery.

    Science.gov (United States)

    Rydstedt, Leif W; Devereux, Jason J

    2013-11-05

    The purpose of the study was to assess the impact of job strain and sleep quality on the diurnal pattern of cortisol reactivity, measured by awakening and evening (10 PM) saliva cortisol. The sample consisted of 76 British white-collar workers (24 women, 52 men; mean age 45.8 years). Sleep quality and job strain were assessed in a survey distributed just before the cortisol sampling. Both input variables were dichotomized about the median and factorial ANOVA was used for the statistical analysis. Low sleep quality was significantly associated with lower morning cortisol secretion. While job strain had no main effects on the cortisol reactivity there was a significant interaction effect between the input variables on morning cortisol secretion. These findings tentatively support the hypothesis that lack of sleep for workers with high job strain may result in a flattened diurnal cortisol reactivity.

  6. Research on horizontal displacement monitoring of deep soil based on a distributed optical fibre sensor

    Science.gov (United States)

    Huang, Xiaodi; Wang, Yuan; Sun, Yangyang; Zhang, Qinghua; Zhang, Zhenglin; You, Zewei; Ma, Yuan

    2018-01-01

    The traditional measurement method for the horizontal displacement of deep soil usually uses an inclinometer for piecewise measurement and then generates an artificial reading, which takes a long time and often contains errors; in addition, the anti-jamming and long-term stability of the inclinometer is poor. In this paper, a technique for monitoring horizontal displacement based on distributed optical fibres is introduced. The relationship between the strain and the deflection was described by a theoretical model, and the strain distribution of the inclinometer tube was measured by the cables laid on its surface so that the deflection of the inclinometer tube could be calculated by the difference algorithm and regarded as the horizontal displacement of deep soil. The horizontal displacement monitoring technology of deep soil based on distributed optical fibre sensors developed in this paper not only overcame the shortcomings of traditional inclinometer technology to realize automatic real-time monitoring but also allowed for distributed measurement. The experiment was similar to the expected engineering situations, and the deflection calculated from the strain was compared with an inclinometer. The results demonstrated that the relative error between the distributed optical fibre sensors and the inclinometer was less than 8.0%, and the results also verified both the feasibility of using distributed optical fibre to monitor the horizontal displacement of soil as well as the rationality of the theoretical model and difference algorithm. The application of distributed optical fibre in monitoring the horizontal displacement of deep soil in the engineering of foundation pits and slopes can more accurately evaluate the safety of engineering during construction.

  7. Full 3D internal strain measurement for device packaging materials using synchrotron laminography and volumetric digital image correlation method

    International Nuclear Information System (INIS)

    Asada, Takashi; Kimura, Hidehiko; Yamaguchi, Satoshi; Kano, Taiki; Kajiwara, Kentaro

    2014-01-01

    In order to measure full 3D internal strain field of resin molding compound specimens, synchrotron computed tomography and laminography at SPring-8 were performed. Then the reconstructed images were applied to 3D digital image correlation method to compute internal strain field. The results showed that internal strains in resin molding compound could be visualized in this way. (author)

  8. A three-frame digital image correlation (DIC) method for the measurement of small displacements and strains

    International Nuclear Information System (INIS)

    Cofaru, C; Philips, W; Van Paepegem, W

    2012-01-01

    Digital image correlation (DIC) has become a well-established approach for the calculation of full-field displacement and strains within the field of experimental mechanics. Since their introduction, DIC methods have been relying on only two images to measure the displacements and strains that materials undergo under load. It can be foreseen that the use of additional image information for the calculus of displacements and strains, although computationally more expensive, can positively impact DIC method accuracy under both ideal and challenging experimental conditions. Such accuracy improvements are especially important when measuring very small deformations, which still constitutes a great challenge: small displacements and strains translate into equally small digital image intensity changes on the material’s surface, which are affected by the digitization processes of the imaging hardware and by other image acquisition effects such as image noise. This paper proposes a new three-frame Newton–Raphson DIC method and evaluates it from the standpoints of accuracy and speed. The method models the deformations that are to be measured under the assumption that the deformation occurs at approximately the same rate between each two consecutive images in the three image sequences that are employed. The aim is to investigate how the use of image data from more than two images impacts accuracy and what is the effect on the computational speed. The proposed method is compared with the classic two-frame Newton–Raphson method in three experiments. Two experiments rely on numerically deformed images that simulate heterogeneous deformations. The third experiment uses images from a real deformation experiment. Results indicate that although it is computationally more demanding, the three-frame method significantly improves displacement and strain accuracy and is less sensitive to image noise. (paper)

  9. Design of Stress-Strain Measuring System for Bulldozing Plate Based on Virtual Instrument Technology

    International Nuclear Information System (INIS)

    Xu, S C; Li, J Q; Zhang, R

    2006-01-01

    Soil is a kind of discrete, multiphase compound that is composed of soil particles, liquid and air. When soil is disturbed by bulldozing plate, the mechanical behavior of the soil will become very complex. Based on the law of action and reaction, the dynamic mechanical behavior of disturbed soil was indirectly analyzed by measuring and studying the forces on the bulldozing plate by soil currently, so a stress-strain virtual measuring system for bulldozing plate, which was designed by the graphical programming language DASYLab, was used to measure the horizontal force Fz acting on the bulldozing plate. In addition, during the course of design, the experimental complexities and the interferential factors influencing on signal logging were analyzed when bulldozing plate worked, so the anti-jamming methods of hardware and software technology were adopted correlatively. In the end, the horizontal force Fz was analyzed with Error Theory, the result shown that the quantificational analysis of Fz were identical to the qualitative results of soil well, and the error of the whole test system is under 5 percent, so the tress-strain virtual measuring system was stable and credible

  10. Interspecific cooperation: enhanced growth, attachment and strain-specific distribution in biofilms through Azospirillum brasilense-Pseudomonas protegens co-cultivation.

    Science.gov (United States)

    Pagnussat, Luciana A; Salcedo, Florencia; Maroniche, Guillermo; Keel, Christoph; Valverde, Claudio; Creus, Cecilia M

    2016-10-01

    Plant-growth-promoting bacteria belonging to Azospirillum and Pseudomonas genera are major inhabitants of the rhizosphere. Both are increasingly commercialized as crops inoculants. Interspecific interaction in the rhizosphere is critical for inoculants aptness. The objective of this work was to evaluate Azospirillum and Pseudomonas interaction in mixed biofilms by co-cultivation of the model strains Azospirillum brasilense Sp245 and Pseudomonas protegens CHA0. The results revealed enhanced growth of both strains when co-cultured in static conditions. Moreover, Sp245 biofilm formed in plastic surfaces was increased 2-fold in the presence of CHA0. Confocal microscopy revealed highly structured mixed biofilms showing Sp245 mainly on the bottom and CHA0 towards the biofilm surface. In addition, A. brasilense biofilm was thicker and denser when co-cultured with P. protegens. In a colony-colony interaction assay, Sp245 changed nearby CHA0 producing small colony phenotype, which accounts for a diffusible metabolite mediator; though CHA0 spent medium did not affect Sp245 colony phenotype. Altogether, these results point to a cooperative interaction between A. brasilense Sp245 and P. protegens CHA0 in which both strains increase their static growth and produce structured mixed biofilms with a strain-specific distribution. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  11. A comparison of GPS strain rate and seismicity in mainland China

    Science.gov (United States)

    Ye, J.; Liu, M.

    2011-12-01

    The spatial distribution and moment release of earthquakes should correlate to crustal strain rates, assuming most of the crustal strain is released by earthquakes. However, the correlation between seismicity and crustal strain rates is not always clear, especially in continental interiors where large earthquakes are infrequent and earthquake records often incomplete. Here we compare seismicity and crustal strain rates in mainland China, where in the past decades the GPS measurements by the Crustal Motion Observation Network of China and other teams have determined the velocity at more than a thousand sites, allowing a meaningful calculation of the spatial distribution of the crustal strain rates. Our strain-rate map of mainland China is consistent with tectonic activities. The average scalar strain rate in West China is 17.5x10-16, contrasting to the much lower value (2.5x 10-16) in East China. The high strain rates are mainly found in the Tibetan Plateau, with the highest values clearly delineating the major active faults, including the Himalayan main boundary thrust, the Xianshuihe fault, the Longmanshan fault, the Haiyuan fault, and the southern Tianshan boundary fault. North China also has relatively high strain rates, but the high strain rates around the cities of Tangshan and Xingtai likely result from postseismic deformation following the 1966 Xingtai earthquake (M 7.2) and the 1976 Tangshan earthquake (M 7.8). We calculated the seismic moment release using the Chinese earthquake catalog that goes back to more than 2000 years. The spatial pattern of cumulative seismic moment release is generally comparable with that of the strain rates. Regions of major discrepancies include the Weihe-Shanxi grabens, which had numerous large earthquakes but have been quiescent in the past 300 years. When we use smaller time windows (200 or 500 years) to calculate the seismic moment release, we found strongly variable spatial patterns that is generally incomparable with the

  12. Pirani pressure sensor with distributed temperature measurement

    NARCIS (Netherlands)

    de Jong, B.R.; Bula, W.P.; Zalewski, D.R.; van Baar, J.J.J.; Wiegerink, Remco J.

    2003-01-01

    Surface micro-machined distributed Pirani pressure gauges, with designed heater-to-heat sink distances (gap-heights) of 0.35 μm and 1.10 μm, are successfully fabricated, modeled and characterized. Measurements and model response correspond within 5% of the measured value in a pressure range of 10 to

  13. Soil Stress-Strain Behavior: Measurement, Modeling and Analysis

    CERN Document Server

    Ling, Hoe I; Leshchinsky, Dov; Koseki, Junichi; A Collection of Papers of the Geotechnical Symposium in Rome

    2007-01-01

    This book is an outgrowth of the proceedings for the Geotechnical Symposium in Roma, which was held on March 16 and 17, 2006 in Rome, Italy. The Symposium was organized to celebrate the 60th birthday of Prof. Tatsuoka as well as honoring his research achievement. The publications are focused on the recent developments in the stress-strain behavior of geomaterials, with an emphasis on laboratory measurements, soil constitutive modeling and behavior of soil structures (such as reinforced soils, piles and slopes). The latest advancement in the field, such as the rate effect and dynamic behavior of both clay and sand, behavior of modified soils and soil mixtures, and soil liquefaction are addressed. A special keynote paper by Prof. Tatsuoka is included with three other keynote papers (presented by Prof. Lo Presti, Prof. Di Benedetto, and Prof. Shibuya).

  14. IS6110 restriction fragment length polymorphism of Mycobacterium tuberculosis isolated from patients with pulmonary tuberculosis in Campinas, Brazil: evidence of intercontinental distribution of strains

    Directory of Open Access Journals (Sweden)

    Ana Lucia Roscani Calusni

    2003-07-01

    Full Text Available Tuberculosis (TB is a major concern in developing countries. In Brazil, few genotyping studies have been conducted to verify the number of IS6110 copies present in local prevalent strains of Mycobacterium tuberculosis, the distribution and clustering of strains. IS6110 DNA fingerprinting was performed on a sample of M. tuberculosis isolates from patients with AFB smear-positive pulmonary TB, at a hospital in Brazil. The IS6110 profiles were analyzed and compared to a M. tuberculosis database of the Houston Tuberculosis Initiative, Houston, US. Seventy-six fingerprints were obtained from 98 patients. All M. tuberculosis strains had an IS6110 copy number between 5-21 allowing for differentiation of the isolates. Human immunodeficiency virus infection was confirmed in nearly half the patients of whom data was available. Fifty-eight strains had unique patterns, while 17 strains were grouped in 7 clusters (2 to 6 strains. When compared to the HTI database, 6 strains matched isolates from El Paso, Ciudad de Juarez, Houston, and New York. Recently acquired infections were documented in 19% of cases. The community transmission of infection is intense, since some clustered strains were recovered during the four-year study period. The intercontinental dissemination of M. tuberculosis strains is suspected by demonstration of identical fingerprints in a distant country.

  15. Mathematical simulation of gamma-radiation angle distribution measurements

    International Nuclear Information System (INIS)

    Batij, V.G.; Batij, E.V.; Egorov, V.V.; Fedorchenko, D.V.; Kochnev, N.A.

    2008-01-01

    We developed mathematical model of the facility for gamma-radiation angle distribution measurement and calculated response functions for gamma-radiation intensities. We developed special software for experimental data processing, the 'Shelter' object radiation spectra unfolding and Sphere detector (ShD) angle resolution estimation. Neuronet method using for detection of the radiation directions is given. We developed software based on the neuronet algorithm, that allows obtaining reliable distribution of gamma-sources that make impact on the facility detectors at the measurement point. 10 refs.; 15 figs.; 4 tab

  16. Electro-optic measurement of terahertz pulse energy distribution

    NARCIS (Netherlands)

    Sun, J.H.; Gallacher, J.G.; Brussaard, G.J.H.; Lemos, N.; Issac, R.; Huang, Z.X.; Dias, J.M.; Jaroszynski, D.A.

    2009-01-01

    An accurate and direct measurement of the energy distribution of a low repetition rate terahertz electromagnetic pulse is challenging because of the lack of sensitive detectors in this spectral range. In this paper, we show how the total energy and energy density distribution of a terahertz

  17. A Program to Generate a Particle Distribution from Emittance Measurements

    CERN Document Server

    Bouma, DS; Lallement, JB

    2010-01-01

    We have written a program to generate a particle distribution based on emittance measurements in x-x’ and y-y’. The accuracy of this program has been tested using real and constructed emittance measurements. Based on these tests, the distribution generated by the program can be used to accurately simulate the beam in multi-particle tracking codes, as an alternative to a Gaussian or uniform distribution.

  18. Experimental measurements of spatial dose distributions in radiosurgery treatments

    International Nuclear Information System (INIS)

    Avila-Rodriguez, M. A.; Rodriguez-Villafuerte, M.; Diaz-Perches, R.; Perez-Pastenes, M. A.

    2001-01-01

    The measurement of stereotactic radiosurgery dose distributions requires an integrating, high-resolution dosimeter capable of providing a spatial map of absorbed dose. This paper describes the use of a commercial radiochromic dye film (GafChromic MD-55-2) to measure radiosurgery dose distributions with 6 MV X-rays in a head phantom. The response of the MD-55-2 was evaluated by digitizing and analyzing the films with conventional computer systems. Radiosurgery dose distributions were measured using the radiochromic film in a spherical acrylic phantom of 16 cm diameter undergoing a typical SRS treatment as a patient, and were compared with dose distributions provided by the treatment planning system. The comparison lead to mean radial differences of ±0.6 mm, ±0.9 mm, ±1.3 mm, ±1.9 mm, and ±2.8 mm, for the 80, 60, 50, 40, and 30% isodose curves, respectively. It is concluded that the radiochromic film is a convenient and useful tool for radiosurgery treatment planning validation

  19. Measurement of strains at high temperatures by means of a portable holographic moire camera

    Science.gov (United States)

    Sciammarella, C. A.; Bhat, G.; Shao, Y.

    Electronic holographic moire is utilized to measure strains at temperatures up to 1000 C. A CW laser operating at 50 mW and at the wavelength of 632.8 nm is used to illuminate the objects under study. The main variables influencing the fringe patterns visibility are discussed and measurements are performed to obtain the values of these variables in the performed experiments. The coefficient of expansion of an alloy is measured at temperatures ranging from 797 C to 986 C. Excellent agreement is found between the measured values and those provided by the manufacturer.

  20. Measuring hydrogen-isotope distribution profiles

    International Nuclear Information System (INIS)

    Poppe, C.H.

    1977-01-01

    A new nondestructive technique was developed for measuring the depth distribution of hydrogen isotopes absorbed or implanted near the surface of any material. The method allows real-time study of the inventory and diffusion of hydrogen, deuterium, and tritium. Briefly, the technique involves bombarding the surface with a monoenergetic beam of ions chosen for their ability to react with the hydrogen isotope in question and produce fast neutrons. The energy distribution of the neutrons is a sensitive indicator of the energy of the bombarding particles at the instant of reaction, and hence of the depth of the reaction sites below he surface of the material. A sensitivity of one part per million was obtained for tritium in copper. The technique is applicable to several energy-related materials problems. 5 figures

  1. X-Ray Microbeam Measurements of Individual Dislocation Cell Elastic Strains in Deformed Single-Crystal Copper

    Energy Technology Data Exchange (ETDEWEB)

    Levine, Lyle E. [National Institute of Standards and Technology (NIST); Larson, Ben C [ORNL; Yang, Wenge [ORNL; Kassner, Michael E. [University of Southern California; Tischler, Jonathan Zachary [ORNL; Delos-Reyes, Michael A. [University of Southern California; Fields, Richard J. [National Institute of Standards and Technology (NIST); Liu, Wenjun [ORNL

    2006-01-01

    The distribution of elastic strains at the submicrometre length scale within deformed metal single crystals has remarkably broad implications for our understanding of important physical phenomena. These include the evolution of the complex dislocation structures that govern mechanical behaviour within individual grains, the transport of dislocations through such structures, changes in mechanical properties that occur during reverse loading (for example, sheet-metal forming and fatigue), and the analyses of diffraction line profiles for microstructural studies of these phenomena.

  2. Strain-specific viral distribution and neuropathology of feline immunodeficiency virus.

    Science.gov (United States)

    Miller, Craig; Bielefeldt-Ohmann, Helle; MacMillan, Martha; Huitron-Resendiz, Salvador; Henriksen, Steven; Elder, John; VandeWoude, Susan

    2011-10-15

    Feline immunodeficiency virus (FIV) is a naturally occurring lentivirus of domestic cats, and is the causative agent of feline AIDS. Similar to human immunodeficiency virus (HIV), the pathogenesis of FIV involves infection of lymphocytes and macrophages, and results in chronic progressive immune system collapse and death. Neuropathologic correlates of FIV infection have not yet been elucidated, and may be relevant to understanding HIV-associated neurologic disease (neuroAIDS). As in HIV, FIV strains have been shown to express differential tendencies towards development of clinical neuroAIDS. To interrogate viral genetic determinants that might contribute to neuropathogenicity, cats were exposed to two well-characterized FIV strains with divergent clinical phenotypes and a chimeric strain as follows: FIV(PPR) (PPR, relatively apathogenic but associated with neurologic manifestations), FIV(C36) (C36, immunopathogenic but without associated neurologic disease), and Pcenv (a chimeric virus consisting of a PPR backbone with substituted C36 env region). A sham inoculum control group was also included. Peripheral nerve conduction velocity, CNS imaging studies, viral loads and hematologic analysis were performed over a 12 month period. At termination of the study (350 days post-inoculation), brain sections were obtained from four anatomic locations known to be involved in human and primate lentiviral neuroAIDS. Histological and immunohistochemical evaluation with seven markers of inflammation revealed that Pcenv infection resulted in mild inflammation of the CNS, microglial activation, neuronal degeneration and apoptosis, while C36 and PPR strains induced minimal neuropathologic changes. Conduction velocity aberrations were noted peripherally in all three groups at 63 weeks post-infection. Pcenv viral load in this study was intermediate to the parental strains (C36 demonstrating the highest viral load and PPR the lowest). These results collectively suggest that (i) 3' C36

  3. Diffraction grating strain gauge method: error analysis and its application for the residual stress measurement in thermal barrier coatings

    Science.gov (United States)

    Yin, Yuanjie; Fan, Bozhao; He, Wei; Dai, Xianglu; Guo, Baoqiao; Xie, Huimin

    2018-03-01

    Diffraction grating strain gauge (DGSG) is an optical strain measurement method. Based on this method, a six-spot diffraction grating strain gauge (S-DGSG) system has been developed with the advantages of high and adjustable sensitivity, compact structure, and non-contact measurement. In this study, this system is applied for the residual stress measurement in thermal barrier coatings (TBCs) combining the hole-drilling method. During the experiment, the specimen’s location is supposed to be reset accurately before and after the hole-drilling, however, it is found that the rigid body displacements from the resetting process could seriously influence the measurement accuracy. In order to understand and eliminate the effects from the rigid body displacements, such as the three-dimensional (3D) rotations and the out-of-plane displacement of the grating, the measurement error of this system is systematically analyzed, and an optimized method is proposed. Moreover, a numerical experiment and a verified tensile test are conducted, and the results verify the applicability of this optimized method successfully. Finally, combining this optimized method, a residual stress measurement experiment is conducted, and the results show that this method can be applied to measure the residual stress in TBCs.

  4. Distributed optical fiber sensors for integrated monitoring of railway infrastructures

    Science.gov (United States)

    Minardo, Aldo; Coscetta, Agnese; Porcaro, Giuseppe; Giannetta, Daniele; Bernini, Romeo; Zeni, Luigi

    2014-05-01

    We propose the application of a distributed optical fiber sensor based on stimulated Brillouin scattering, as an integrated system for safety monitoring of railway infrastructures. The strain distribution was measured dynamically along a 60 meters length of rail track, as well as along a 3-m stone arch bridge. The results indicate that distributed sensing technology is able to provide useful information in railway traffic and safety monitoring.

  5. Superthermal electron distribution measurements from polarized electron cyclotron emission

    International Nuclear Information System (INIS)

    Luce, T.C.; Efthimion, P.C.; Fisch, N.J.

    1988-06-01

    Measurements of the superthermal electron distribution can be made by observing the polarized electron cyclotron emission. The emission is viewed along a constant magnetic field surface. This simplifies the resonance condition and gives a direct correlation between emission frequency and kinetic energy of the emitting electron. A transformation technique is formulated which determines the anisotropy of the distribution and number density of superthermals at each energy measured. The steady-state distribution during lower hybrid current drive and examples of the superthermal dynamics as the runaway conditions is varied are presented for discharges in the PLT tokamak. 15 refs., 8 figs

  6. Evaluation of Pressure Pain Threshold as a Measure of Perceived Stress and High Job Strain

    DEFF Research Database (Denmark)

    Hven, Lisbeth; Frost, Poul; Bonde, Jens Peter Ellekilde

    2017-01-01

    pressure pain algometry measurements of PPT on the trapezius and supraspinatus muscles and the tibia. Associations of stress symptoms and job strain with PPT of each site was analyzed for men and women separately with adjustment for age body mass index, and discomfort in the anatomical region closest...... to the point of pressure algometry using multivariable linear regression. RESULTS: We found significant inverse associations between perceived stress and PPT in both genders in models adjusting for age and body mass index: the higher level of perceived stress, the lower the threshold. For job strain...... associations between perceived stress and PPT, the discriminative capability of PPT to distinguish individuals with and without stress is low. PPT measured by pressure algometry seems not applicable as a diagnostic tool of a state of mental stress....

  7. Psychosocial Job Strain and Sleep Quality Interaction Leading to Insufficient Recovery

    Directory of Open Access Journals (Sweden)

    Leif W. Rydstedt

    2013-11-01

    Full Text Available The purpose of the study was to assess the impact of job strain and sleep quality on the diurnal pattern of cortisol reactivity, measured by awakening and evening (10 PM saliva cortisol. The sample consisted of 76 British white-collar workers (24 women, 52 men; mean age 45.8 years. Sleep quality and job strain were assessed in a survey distributed just before the cortisol sampling. Both input variables were dichotomized about the median and factorial ANOVA was used for the statistical analysis. Low sleep quality was significantly associated with lower morning cortisol secretion. While job strain had no main effects on the cortisol reactivity there was a significant interaction effect between the input variables on morning cortisol secretion. These findings tentatively support the hypothesis that lack of sleep for workers with high job strain may result in a flattened diurnal cortisol reactivity.

  8. Analysis of stress- strain distribution of dowel and glue line in L-type furniture joint by means of finite element method

    Directory of Open Access Journals (Sweden)

    mossayeb dalvand

    2017-08-01

    Full Text Available In this study 3D stress-strain distribution of dowel and glue line on L-type joints made of plywood doweled was investigated. Members of joints made of 11-ply hardwood plywood (Hornbeam, Beech and Alder that were 19 mm in thickness. In this study effect of beech dowels in three levels diameters (6, 8 and 10 mm and penetration of depth (9, 13 and 17 mm on bending moment capacity of L-type joints under compression loading was investigated as experimental test, then stress-strain distribution of wood dowel and glue line in specimens were simulated by means of ANSYS 15 software with finite element method (FEM.Results have shown that bending moment resistance increased with increasing dowel diameter from 6 to 8 mm, but downward trend was observed with increasing 8 to 10 mm in dowel diameter. Bending moment resistance increased with increasing penetration depth. Also, result obtained of simulation by means of ANSYS software have shown that stress-strain in dowel and glue line increased with increasing diameter of dowel and Increasing stress in joints made of diameter dowel 10 mm due to fracture in joints and decrease in resistance once. According to results obtained of model analysis, the ultimate stress of dowel and glue line occurred in the area that joints were contacted.

  9. Simulation of the measure of the microparticle size distribution in two dimensions

    International Nuclear Information System (INIS)

    Lameiras, F.S.; Pinheiro, P.

    1987-01-01

    Different size distributions of plane figures were generated in a computer as a simply connected network. These size distributions were measured by the Saltykov method for two dimensions. The comparison between the generated and measured distributions showed that the Saltkov method tends to measure larger scattering than the real one and to move the maximum of the real distribution to larger diameters. These erros were determined by means of the ratio of the perimeter of the figures per unit area directly measured and the perimeter calculated from the size distribution obtained by using the SaltyKov method. (Author) [pt

  10. A temperature-compensated high spatial resolution distributed strain sensor

    International Nuclear Information System (INIS)

    Belal, Mohammad; Cho, Yuh Tat; Ibsen, Morten; Newson, Trevor P

    2010-01-01

    We propose and demonstrate a scheme which utilizes the temperature dependence of spontaneous Raman scattering to provide temperature compensation for a high spatial resolution Brillouin frequency-based strain sensor

  11. Simple Numerical Simulation of Strain Measurement

    Science.gov (United States)

    Tai, H.

    2002-01-01

    By adopting the basic principle of the reflection (and transmission) of a plane polarized electromagnetic wave incident normal to a stack of films of alternating refractive index, a simple numerical code was written to simulate the maximum reflectivity (transmittivity) of a fiber optic Bragg grating corresponding to various non-uniform strain conditions including photo-elastic effect in certain cases.

  12. An application of the recrystallization method for the observation of plastic strain distribution around SCC cracks in sensitized SUS 304 stainless steels

    International Nuclear Information System (INIS)

    Tokiwai, Moriyasu

    1981-01-01

    Various types of stress corrosion cracking (SCC) testing methods have been developed since the SCC was discovered in type 304 stainless steel of BWR cooling pipes. With regard to the countermeasures for SCC, it is essential to evaluate the SCC susceptibility under the simulated or accelerated testing conditions. Among various acceleration SCC tests, the slow strain rate technique (SSRT) test has been used most widely. The SCC susceptibility, in almost cases, has been evaluated not on the base of the crack behavior but of the reduction of stress or strain under the corrosive environment. It is well known that the intensively deformed zone (plastic zone) is formed at the crack tip in fatigue and creep phenomena, but such plastic zone related with the resistance of crack extention has not been studied in SCC phenomenon. The objective of this study is to confirm the existence of the plastic zone at tips of SCC cracks by the application of the recrystallization method. The shape and the distribution of the plastic zone was measured by use of optical and scanning electron microscope in sensitized specimens SSRT tested in high temperature water containing various concentrations of dissolved oxygen. Results obtained are discussed in relation to the susceptibility of SCC. (author)

  13. Strain distribution and failure mode of polymer separators for Li-ion batteries under biaxial loading

    Science.gov (United States)

    Kalnaus, Sergiy; Kumar, Abhishek; Wang, Yanli; Li, Jianlin; Simunovic, Srdjan; Turner, John A.; Gorney, Phillip

    2018-02-01

    Deformation of polymer separators for Li-ion batteries has been studied under biaxial tension by using a dome test setup. This deformation mode provides characterization of separator strength under more complex loading conditions, closer representing deformation of an electric vehicle battery during crash event, compared to uniaxial tension or compression. Two polymer separators, Celgard 2325 and Celgard 2075 were investigated by deformation with spheres of three different diameters. Strains in separators were measured in situ by using Digital Image Correlation (DIC) technique. The results show consistent rupture of separators along the machine direction coinciding with areas of high strain accumulation. The critical first principal strain for failure was independent of the sphere diameter and was determined to be approximately 34% and 43% for Celgard 2325 and Celgard 2075 respectively. These values can be taken as a criterion for internal short circuit in a battery following an out-of-plane impact. A Finite Element (FE) model was built with the anisotropic description of separator behavior, derived from tensile tests in orthogonal directions. The results of simulations predicted the response of separator rather well when compared to experimental results for various sizes of rigid sphere.

  14. Investigation on field method using strain measurement on pipe surface to measure pressure pulsation in piping systems

    International Nuclear Information System (INIS)

    Maekawa, Akira; Tsuji, Takashi; Takahashi, Tsuneo; Kato, Minoru

    2013-01-01

    Accurate evaluation of the occurrence location and amplitude of pressure pulsations in piping systems can lead to efficient plant maintenance by preventing fatigue failure of piping and components because the pulsations can be one of the main causes of vibration fatigue and acoustic noise in piping. A non-destructive field method to measure pressure pulsations easily and directly was proposed to replace conventional methods such as prediction using numerical simulations and estimation using locally installed pressure gauges. The proposed method was validated experimentally by measuring pulsating flow in a mock-up piping system. As a result, it was demonstrated that the method to combine strain measurement on the outer surface of pipe with the formula for thick-walled cylinders could measure amplitudes and behavior of the pressure pulsations with a practical accuracy. Factors affecting the measurement accuracy of the proposed method were also discussed. Furthermore, the applicability of the formula for thin-walled cylinders was examined for variously shaped pipes. (author)

  15. Measurement of C-14 distribution in forest around nuclear facilities

    International Nuclear Information System (INIS)

    Atarashi-Andoh, Mariko; Amano, Hikaru; Arakhatoon, Jahan

    2003-01-01

    A simple analytical method of C-14 measurement using fast bomb combustion and liquid scintillation counting (LSC) has been developed for measuring C-14 distribution in the terrestrial environment. Specific activities of C-14 in cedar leaves and soils collected from an area around nuclear facilities and control areas were measured using this method. Depth distribution of Cs-137 in soils was also measured at the same sampling sites and compared with the depth distribution of C-14. C-14 specific activity in cedar leaves examined around nuclear facilities exceeded that in the control areas by 8 to 30 mBq (g carbon) -1 . The depth distribution of C-14 in forest soil shows that C-14 has peak values in the top 10 cm of the soil profiles ascribed to the highest bomb C-14 level in the 1960's. The data were made available to assess the behavior of fallout C-14 in the surface environment. (author)

  16. Direct measurement of conformational strain energy in protofilaments curling outward from disassembling microtubule tips.

    Science.gov (United States)

    Driver, Jonathan W; Geyer, Elisabeth A; Bailey, Megan E; Rice, Luke M; Asbury, Charles L

    2017-06-19

    Disassembling microtubules can generate movement independently of motor enzymes, especially at kinetochores where they drive chromosome motility. A popular explanation is the 'conformational wave' model, in which protofilaments pull on the kinetochore as they curl outward from a disassembling tip. But whether protofilaments can work efficiently via this spring-like mechanism has been unclear. By modifying a previous assay to use recombinant tubulin and feedback-controlled laser trapping, we directly demonstrate the spring-like elasticity of curling protofilaments. Measuring their mechanical work output suggests they carry ~25% of the energy of GTP hydrolysis as bending strain, enabling them to drive movement with efficiency similar to conventional motors. Surprisingly, a β-tubulin mutant that dramatically slows disassembly has no effect on work output, indicating an uncoupling of disassembly speed from protofilament strain. These results show the wave mechanism can make a major contribution to kinetochore motility and establish a direct approach for measuring tubulin mechano-chemistry.

  17. Measurement of the size distributions of radon progeny in indoor air

    International Nuclear Information System (INIS)

    Hopke, P.K.; Ramamurthi, M.; Li, C.S.

    1990-01-01

    A major problem in evaluating the health risk posed by airborne radon progeny in indoor atmospheres is the lack of available information on the activity-weighted size distributions that occur in the domestic environment. With an automated, semicontinuous, graded screen array system, we made a series of measurements of activity-weighted size distributions in several houses in the northeastern United States. Measurements were made in an unoccupied house, in which human aerosol-generating activities were simulated. The time evolution of the aerosol size distribution was measured in each situation. Results of these measurements are presented

  18. Resonance line shape, strain and electric potential distributions of composite magnetoelectric sensors

    Directory of Open Access Journals (Sweden)

    Martina Gerken

    2013-06-01

    Full Text Available Multiferroic composite magnetoelectric (ME sensors are based on the elastic coupling of a magnetostrictive phase and a piezoelectric phase. A deformation of the magnetostrictive phase causes strain in the piezoelectric phase and thus an induced voltage. Such sensors may be applied both for static as well as for dynamic magnetic field measurements. Particularly high sensitivities are achieved for operation at a mechanical resonance. Here, the resonance line shape of layered (2-2 composite cantilever ME sensors at the first bending-mode resonance is investigated theoretically. Finite element method (FEM simulations using a linear material model reveal an asymmetric resonance profile and a zero-response frequency for the ME coefficient. Frequency-dependent strain and electric potential distributions inside the magnetoelectric composite are studied for the case of a magnetostrictive-piezoelectric bilayer. It is demonstrated that a positive or a negative voltage may be induced across the piezoelectric layer depending on the position of the neutral plane. The frequency-dependent induced electric potential is investigated for structured cantilevers that exhibit magnetostriction only at specific positions. For static operation an induced voltage is obtained locally at positions with magnetostriction. In addition to this direct effect a resonance-assisted effect is observed for dynamic operation. Magnetostriction in a limited area of the cantilever causes a global vibration of the cantilever. Thus, deformation of the piezoelectric layer and an induced electric potential also occur in areas of the cantilever without magnetostriction. The direct and the resonance-assisted pathway may induce voltages of equal or of opposite sign. The net induced voltage results from the superposition of the two effects. As the resonance-assisted induced voltage changes sign upon passing the resonance frequency, while the direct component is constant, an asymmetric line

  19. Effect of out-of-plane specimen movement on strain measurement using digital-image-correlation-based video measurement in 2D and 3D

    DEFF Research Database (Denmark)

    Poling, Joel; Desai, Niranjan; Fischer, Gregor

    2018-01-01

    This study determined the effect of specimen out-of-plane movement relative to the sensor, on the accuracy of strains measured made applying 2D and 3D measurement approaches employing the state-of-the-art digital-image-correlation (DIC)-based tool iMETRUM. DIC provides a convenient and inexpensive...

  20. Characterization of the failure in Callovo-Oxfordian argillite under plane strain compression using full field measurements

    International Nuclear Information System (INIS)

    Besuelle, P.

    2012-01-01

    Document available in extended abstract form only. Failure by strain localization is commonly observed in geo-materials. Cracks are detected in Underground Research Laboratories (URL) on the walls of galleries (e.g., Andra in Meuse/Haute Marne laboratory, SCK-CEN in Mol), they have been induced by the stress relaxation that results from the excavation. The cracks represent material discontinuities which could impact the flow properties of the rock mass in some circumstances. Generally, experimental characterization of the localization in rocks is performed with classical axisymmetric triaxial compression tests. The effect of the confining pressure can be observed on several aspects: onset of localization, pattern of localization, porosity evolution inside bands or cracks aperture, grain scale mechanisms of deformation (e.g., [1]). However the history (time evolution) of the localization is not accessible because the observations are post-mortem. Strain field measurement and evolution in time of the strain field are particularly useful to study the strain localization (initiation of the deformation bands) and the post-localization regime. Such tools have been developed for soils (e.g., sand specimens in plane strain condition [2] or in triaxial conditions using X-ray tomography [3]). Similar developments for rocks are still difficult, especially because the pertinent confining pressure to reproduce in situ stresses are higher than for soils. We present here first results obtained in a new true triaxial apparatus that allows observation of the rock specimen under loading and especially the complex development of deformation bands and faults. As for [4] and [5], the three principal stresses are different. However, for selected tests discussed here, the intermediate stress is controlled in order to impose a plane strain condition (zero strain in this direction). Observation of a specimen under load is possible as one surface of the prismatic specimen, which is

  1. 3D non-affine finite strains measured in isolated bovine annulus fibrosus tissue samples

    NARCIS (Netherlands)

    Huyghe, J.M.R.J.; Talen-Jongeneelen, C.J.M.

    2012-01-01

    Understanding of the mechanics of disc tissue calls for measurement of strains in physiological conditions. Because the intervertebral disc is gripped between two vertebrae, the swelling is constrained in vivo, resulting in a intradiscal pressure of 0.1–0.2 MPa in supine position. The excision of

  2. Model-independent determination of the strain distribution for a SiGe/Si superlattice using X-ray diffractometry data

    International Nuclear Information System (INIS)

    Nikulin, A.Y.; Stevenson, A.W.; Hashizume, H.

    1996-01-01

    The strain distribution in a Si 0.9 Ge 0.l/Si superlattice is determined from x-ray diffractometry data with a 25 Angstroms depth resolution. A logarithmic dispersion relation is used to determine the phase of the structure factor with information available a priori on the sample structure. Phase information is obtained from the observed reflection intensity via a logarithmic Hilbert transform and the a priori information is used to select the zeros to be included in the solution. The reconstructed lattice strain profile clearly resolves SiGe and Si layers of 90 - 160 Angstroms thickness alternately stacked on a silicon substrate. The SiGe layer is found to have a lattice spacing in the surface-normal direction significantly smaller than predicted by Vegard's law. The result is supported by very good agreement of the simulated rocking curve profile with the observation. 18 refs., 1 tab., 5 figs

  3. A high energy microscope for local strain measurements within bulk materials

    DEFF Research Database (Denmark)

    Lienert, U.; Poulsen, H.F.; Martins, R.V.

    2000-01-01

    A novel diffraction technique for local, three dimensional strain scanning within bulk materials is presented. The technique utilizes high energy, micro-focussed synchrotron radiation which can penetrate several millimeters into typical metals. The spatial resolution can be as narrow as 1 mum...... in one dimension and in three dimensions about 5x10x100 mum(3) Bulk properties are probed non-destructively and in-situ measurements during thermo-mechanical processing are feasible. A dedicated experimental station has been constructed at the ID11 beamline of the European Synchrotron Radiation Facility...

  4. Passive wireless antenna sensor for strain and crack sensing—electromagnetic modeling, simulation, and testing

    International Nuclear Information System (INIS)

    Yi, Xiaohua; Cho, Chunhee; Wang, Yang; Cooper, James; Tentzeris, Manos M; Leon, Roberto T

    2013-01-01

    This research investigates a passive wireless antenna sensor designed for strain and crack sensing. When the antenna experiences deformation, the antenna shape changes, causing a shift in the electromagnetic resonance frequency of the antenna. A radio frequency identification (RFID) chip is adopted for antenna signal modulation, so that a wireless reader can easily distinguish the backscattered sensor signal from unwanted environmental reflections. The RFID chip captures its operating power from an interrogation electromagnetic wave emitted by the reader, which allows the antenna sensor to be passive (battery-free). This paper first reports the latest simulation results on radiation patterns, surface current density, and electromagnetic field distribution. The simulation results are followed with experimental results on the strain and crack sensing performance of the antenna sensor. Tensile tests show that the wireless antenna sensor can detect small strain changes lower than 20 με, and can perform well at large strains higher than 10 000 με. With a high-gain reader antenna, the wireless interrogation distance can be increased up to 2.1 m. Furthermore, an array of antenna sensors is capable of measuring the strain distribution in close proximity. During emulated crack and fatigue crack tests, the antenna sensor is able to detect the growth of a small crack. (paper)

  5. Comparing downside risk measures for heavy tailed distributions

    NARCIS (Netherlands)

    Daníelsson, J.; Jorgensen, B.N.; Sarma, M.; Vries, de C.G.

    2006-01-01

    Using regular variation to define heavy tailed distributions, we show that prominent downside risk measures produce similar and consistent ranking of heavy tailed risk. Thus, regardless of the particular risk measure being used, assets will be ranked in a similar and consistent manner for heavy

  6. Development of piping strain sensor for stress evaluation

    International Nuclear Information System (INIS)

    Takahama, Tsunemichi; Nishimura, Kazuma; Ninomiya, Seiichiro; Matsumoto, Yoshihiro; Harada, Yutaka

    2014-01-01

    In a small diameter piping, stresses are generated due to internal fluid or pump vibrations especially around the welding parts. Authors have successfully developed a pipe strain sensor which is able to measure such stresses. Unlike conventional methods using strain gages and adhesive bond, the sensor can measure the strain without putting adhesive bond on the piping surface. However, the strain sensor can provide measurements with a level of accuracy equivalent to that of conventional method using strain gages and adhesive bond. Accordingly, the strain sensor can significantly reduce the working time without any loss of the measurement accuracy. (author)

  7. The impact of retirement account distributions on measures of family income.

    Science.gov (United States)

    Iams, Howard M; Purcell, Patrick J

    2013-01-01

    In recent decades, employers have increasingly replaced defined benefit (DB) pensions with defined contribution (DC) retirement accounts for their employees. DB plans provide annuities, or lifetime benefits paid at regular intervals. The timing and amounts of DC distributions, however, may vary widely. Most surveys that provide data on the family income of the aged either collect no data on nonannuity retirement account distributions, or exclude such distributions from their summary measures of family income. We use Survey of Income and Program Participation (SIPP) data for 2009 to estimate the impact of including retirement account distributions on total family income calculations. We find that about one-fifth of aged families received distributions from retirement accounts in 2009. Measured mean income for those families would be about 15 percent higher and median income would be 18 percent higher if those distributions were included in the SIPP summary measure of family income.

  8. Seafloor geodesy: Measuring surface deformation and strain-build up

    Science.gov (United States)

    Kopp, Heidrun; Lange, Dietrich; Hannemann, Katrin; Petersen, Florian

    2017-04-01

    Seafloor deformation is intrinsically related to tectonic processes, which potentially may evolve into geohazards, including earthquakes and tsunamis. The nascent scientific field of seafloor geodesy provides a way to monitor crustal deformation at high resolution comparable to the satellite-based GPS technique upon which terrestrial geodesy is largely based. The measurements extract information on stress and elastic strain stored in the oceanic crust. Horizontal seafloor displacement can be obtained by acoustic/GPS combination to provide absolute positioning or by long-term acoustic telemetry between different beacons fixed on the seafloor. The GeoSEA (Geodetic Earthquake Observatory on the SEAfloor) array uses acoustic telemetry for relative positioning at mm-scale resolution. The transponders within an array intercommunicate via acoustic signals for a period of up to 3.5 years. The seafloor acoustic transponders are mounted on 4 m high tripod steel frames to ensure clear line-of-sight between the stations. The transponders also include high-precision pressure sensors to monitor vertical movements and dual-axis inclinometers in order to measure their level as well as any tilt of the seafloor. Sound velocity sensor measurements are used to correct for water sound speed variations. A further component of the network is GeoSURF, a self-steering autonomous surface vehicle (Wave Glider), which monitors system health and is able to upload the seafloor data to the sea surface and to transfer it via satellite. The GeoSEA array is capable of both continuously monitoring horizontal and vertical ground displacement rates along submarine fault zones and characterizing their behavior (locked or aseismically creeping). Seafloor transponders are currently installed along the Siliviri segment of the North Anatolian Fault offshore Istanbul for measurements of strain build-up along the fault. The first 18 month of baseline ranging were analyzed by a joint-least square inversion

  9. Evaluation of stress distribution due to shearing in non-oriented electrical steel by using synchrotron radiation

    Directory of Open Access Journals (Sweden)

    Yoshiaki Zaizen

    2016-05-01

    Full Text Available The influence of the shearing process on the iron loss of non-oriented electrical steels with grain sizes of 10 μm-150 μm was investigated. The deterioration ratio of iron loss was clearly smaller in sample with small grain sizes. The droop height, reflecting the amount of plastic deformation, displayed a good relationship with the deterioration of iron loss under the effect of the material grain size. To clarify the strain distribution around the sheared edge, the elastic strain in a sheet sample with the thickness of 0.30 mm and grain size of 10 μm was evaluated by using synchrotron radiation. The width of the region of elastic strain due to shearing was two or three times of the material thickness. The results of the plastic strain distribution obtained by the measurements were then used to estimate the iron loss deterioration rate in 5 mm width sheared samples. The estimated loss deteriotation coincided with the actual measured iron loss.

  10. Evaluation of stress distribution due to shearing in non-oriented electrical steel by using synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Zaizen, Yoshiaki, E-mail: y-zaizen@jfe-steel.co.jp; Omura, Takeshi; Senda, Kunihiro [Steel Research Laboratory, JFE Steel Corporation, Kawasakidori 1,Mizushima, Kurashiki,712-8511 (Japan); Fukumura, Masaru [Steel Research Laboratory, JFE Steel Corporation, Kawasaki, Kanagawa 210-0855 (Japan); Toda, Hiroaki [Steel Business Planning Dept, JFE Steel Corporation, Tokyo 100-0011 (Japan)

    2016-05-15

    The influence of the shearing process on the iron loss of non-oriented electrical steels with grain sizes of 10 μm-150 μm was investigated. The deterioration ratio of iron loss was clearly smaller in sample with small grain sizes. The droop height, reflecting the amount of plastic deformation, displayed a good relationship with the deterioration of iron loss under the effect of the material grain size. To clarify the strain distribution around the sheared edge, the elastic strain in a sheet sample with the thickness of 0.30 mm and grain size of 10 μm was evaluated by using synchrotron radiation. The width of the region of elastic strain due to shearing was two or three times of the material thickness. The results of the plastic strain distribution obtained by the measurements were then used to estimate the iron loss deterioration rate in 5 mm width sheared samples. The estimated loss deteriotation coincided with the actual measured iron loss.

  11. Effect of loading mode on lattice strain measurements via neutron diffraction

    International Nuclear Information System (INIS)

    Skippon, T.; Clausen, B.; Daymond, M.R.

    2013-01-01

    The study of lattice strain evolution during uniaxial deformation via in situ neutron diffraction is a well established technique for characterizing the deformation behavior of metals. However, the relatively low flux of neutron facilities results in count times on the order of several minutes, requiring experimenters to choose between either applying a very slow strain rate, or loading the sample incrementally rather than continuously. Here we investigate the effects on lattice strain data obtained by using stress, strain, and position controlled incremental loading, as well as continuous loading, on samples of Zircaloy-2 under uniaxial compression. It was found that both qualitative and quantitative differences arise in the lattice strain behavior of certain grain families, particularly {101 ¯ 0} and {112 ¯ 0}, while other grain families show no discernible effect. The differences in lattice strain evolution brought on by the variation in loading modes are believed to be the result of thermally activated dislocation motion

  12. New method for exact measurement of thermal neutron distribution in elementary cell

    International Nuclear Information System (INIS)

    Takac, S.M.; Krcevinac, S.B.

    1966-06-01

    Exact measurement of thermal neutron density distribution in an elementary cell necessitates the knowledge of the perturbations involved in the cell by the measuring device. A new method has been developed in which a special stress is made to evaluate these perturbations by measuring the response from the perturbations introduced in the elementary cell. The unperturbed distribution was obtained by extrapolation to zero perturbation. The final distributions for different lattice pitches were compared with a THERMOS-type calculation. As a pleasing fact a very good agreement has been reached, which dissolves the long existing disagreement between THERMOS calculations and measured density distribution (author)

  13. New method for exact measurement of thermal neutron distribution in elementary cell

    Energy Technology Data Exchange (ETDEWEB)

    Takac, S M; Krcevinac, S B [Institute of nuclear sciences Boris Kidric, Vinca, Beograd (Yugoslavia)

    1966-06-15

    Exact measurement of thermal neutron density distribution in an elementary cell necessitates the knowledge of the perturbations involved in the cell by the measuring device. A new method has been developed in which a special stress is made to evaluate these perturbations by measuring the response from the perturbations introduced in the elementary cell. The unperturbed distribution was obtained by extrapolation to zero perturbation. The final distributions for different lattice pitches were compared with a THERMOS-type calculation. As a pleasing fact a very good agreement has been reached, which dissolves the long existing disagreement between THERMOS calculations and measured density distribution (author)

  14. INDIAN POINT REACTOR REACTIVITY AND FLUX DISTRIBUTION MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Batch, M. L.; Fischer, F. E.

    1963-11-15

    The reactivity of the Indian Point core was measured near zero reactivity at various shim and control rod patterns. Flux distribution measurements were also made, and the results are expressed in terms of power peaking factors and normalized detector response during rod withdrawal. (D.L.C.)

  15. Comparison of the strain field of abdominal aortic aneurysm measured by magnetic resonance imaging and stereovision: a feasibility study for prediction of the risk of rupture of aortic abdominal aneurysm.

    Science.gov (United States)

    Wang, Yufei; Joannic, David; Delassus, Patrick; Lalande, Alain; Juillion, Patrick; Fontaine, Jean-François

    2015-04-13

    The prediction of the risk of rupture of abdominal aortic aneurysm (AAA) is a complex problem. Currently the criteria to predict rupture of abdominal aortic aneurysms are aneurysm diameter and growth rates. It is generally believed that study of the wall strain distribution could be helpful to find a better decision criterion for surgery of aortic aneurysms before their rupture. The wall strain distribution depends on many biological and biomechanical factors such as elastic properties of the aorta, turbulent blood flow, anatomy of the aorta, presence of thrombus or not and so on. Recently, numerical simulations to estimate rupture-potential have received many attentions. However, none of the medical imaging tools for screening and monitoring of AAAs were studied in terms of mechanical behavior and experimentally to demonstrate their capability to measure relevant variables. The aim of this study was to develop a metrological approach for deployment testing of the ability of techniques for measuring local in-vitro deformations based on comparison of stereovision and MRI. In this paper, we present the implementation approach and results of the study based on cylindrical phantoms with or without AAA representing, respectively, healthy and unhealthy artery. Through this study, an experimental device was developed for the behavior study of AAA during a cardiac cycle. The results show that the stereovision techniques used in laboratory is well suited and is qualitatively and quantitatively equivalent with MRI measurements. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Estimation of Staphylococcus aureus growth parameters from turbidity data: characterization of strain variation and comparison of methods.

    Science.gov (United States)

    Lindqvist, R

    2006-07-01

    Turbidity methods offer possibilities for generating data required for addressing microorganism variability in risk modeling given that the results of these methods correspond to those of viable count methods. The objectives of this study were to identify the best approach for determining growth parameters based on turbidity data and use of a Bioscreen instrument and to characterize variability in growth parameters of 34 Staphylococcus aureus strains of different biotypes isolated from broiler carcasses. Growth parameters were estimated by fitting primary growth models to turbidity growth curves or to detection times of serially diluted cultures either directly or by using an analysis of variance (ANOVA) approach. The maximum specific growth rates in chicken broth at 17 degrees C estimated by time to detection methods were in good agreement with viable count estimates, whereas growth models (exponential and Richards) underestimated growth rates. Time to detection methods were selected for strain characterization. The variation of growth parameters among strains was best described by either the logistic or lognormal distribution, but definitive conclusions require a larger data set. The distribution of the physiological state parameter ranged from 0.01 to 0.92 and was not significantly different from a normal distribution. Strain variability was important, and the coefficient of variation of growth parameters was up to six times larger among strains than within strains. It is suggested to apply a time to detection (ANOVA) approach using turbidity measurements for convenient and accurate estimation of growth parameters. The results emphasize the need to consider implications of strain variability for predictive modeling and risk assessment.

  17. The effects of perturbations on the strain distribution in numerical simulations - elasto-viscoplastic modeling of boudinage as a case study

    Science.gov (United States)

    Peters, Max; Karrech, Ali; Poulet, Thomas; Herwegh, Marco; Regenauer-Lieb, Klaus

    2014-05-01

    During necking of a mechanically stiffer layer embedded in a weaker matrix, relatively large amounts of strain localize in small areas. As this deformation style appears under distinct geological conditions, necking phenomena, e.g. boudinaged veins, are associated with a variety of deformation modes. So far, there exists rather limited knowledge about the origin of instabilities and their role as precursory structures, i.e. strong localization of elastic energy affecting further plastic deformation (e.g. Regenauer-Lieb & Yuen, 1998; 2004; Karrech et al., 2011a). We applied the finite element solver ABAQUS in order to investigate the 2-D strain distribution in layers including different mechanical material properties during plane strain co-axial deformation. First, linear perturbation analyses were performed in order to evaluate the imperfection sensitivity in the elastic and viscous regimes. We perform a classical modal analysis to determine the natural mode shapes and frequencies of our geological structure during arbitrary vibrations. This analysis aims at detecting the eigenmodes of the geological structure, which are sinusoidal vibrations with geometry specific natural modal shapes and frequencies. The eigenvalues represent the nodal points where the onset of (visco)-elasto-plastic localization can initiate in the structure (Rice, 1977). The eigenmodes, eigenvalues and eigenvectors are highly sensitive to the layer-box' aspect ratio and differences in Young's moduli, or effective viscosity, respectively. Boundary effect-free strain propagation occurs for layer-box aspect ratios smaller than 1:10. Second, these preloading structures were used as seeds for imperfections in elasto-viscoplastic numerical modeling of continuous necking of a coarse-grained mineral layer embedded in a finer-grained matrix (pinch-and-swell type of boudinage), following the thermo-mechanical coupling of grain size evolutions by Herwegh et al. (in press). The evolution of symmetric necks

  18. Particle size distribution measurements of radionuclides from Chernobyl

    International Nuclear Information System (INIS)

    Georgi, B.; Tschiersch, J.

    1988-01-01

    Characteristics of the size distribution of the Chernobyl aerosol have been measured at four locations along the trajectory of the cloud. Changes in time and differences between 131 I and the other isotopes are explained by aerosol physical processes. The relevance of the measurements for dose calculations are discussed

  19. Critical strain region evaluation of self-assembled semiconductor quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Sales, D L [Departamento de Ciencia de los Materiales e I. M. y Q. I., Universidad de Cadiz, Puerto Real, Cadiz (Spain); Pizarro, J [Departamento de Lenguajes y Sistemas Informaticos, Universidad de Cadiz, Puerto Real, Cadiz (Spain); Galindo, P L [Departamento de Lenguajes y Sistemas Informaticos, Universidad de Cadiz, Puerto Real, Cadiz (Spain); Garcia, R [Departamento de Ciencia de los Materiales e I. M. y Q. I., Universidad de Cadiz, Puerto Real, Cadiz (Spain); Trevisi, G [CNR-IMEM Institute, Parco delle Scienze 37a, 43100, Parma (Italy); Frigeri, P [CNR-IMEM Institute, Parco delle Scienze 37a, 43100, Parma (Italy); Nasi, L [CNR-IMEM Institute, Parco delle Scienze 37a, 43100, Parma (Italy); Franchi, S [CNR-IMEM Institute, Parco delle Scienze 37a, 43100, Parma (Italy); Molina, S I [Departamento de Ciencia de los Materiales e I. M. y Q. I., Universidad de Cadiz, Puerto Real, Cadiz (Spain)

    2007-11-28

    A novel peak finding method to map the strain from high resolution transmission electron micrographs, known as the Peak Pairs method, has been applied to In(Ga)As/AlGaAs quantum dot (QD) samples, which present stacking faults emerging from the QD edges. Moreover, strain distribution has been simulated by the finite element method applying the elastic theory on a 3D QD model. The agreement existing between determined and simulated strain values reveals that these techniques are consistent enough to qualitatively characterize the strain distribution of nanostructured materials. The correct application of both methods allows the localization of critical strain zones in semiconductor QDs, predicting the nucleation of defects, and being a very useful tool for the design of semiconductor devices.

  20. Strain and temperature measurement in pultrusion processes by fiber Bragg grating sensors

    Science.gov (United States)

    Tucci, Fausto; Rubino, Felice; Carlone, Pierpaolo

    2018-05-01

    Injection Pultrusion (IP) is one of the most effective processes, in terms of productivity and costs, to manufacture fiber reinforced polymers. In IP roving of fiber are driven through an injection chamber in which they are impregnated by the resin and then formed in a shaped die. The die is heated in order to cure the resin. Pultruded products are in most cases characterized by constant cross-section profile, whereas unidirectional long fibers are mainly used as reinforcing material. Two relevant phenomena occur within the injection chamber and the heated die, namely the impregnation of the fibers and the polymerization of the resin. Furthermore, thermal expansion, resin chemical shrinkage and the interaction between the die and the impregnated fibers strongly influence the process [1]. Clearly, thermal and mechanical fields significantly impact on these strictly chained behaviours. The use of thermocouples to evaluate temperature within pultrusion die is already widespread, but they are not capable to acquire any information concerning stress-strain levels. In the present work Fibers Bragg Gratings (FBG) sensors were used to measure thermal and strain profiles in selected material location within the injection chamber and the curing die. Being the differences among the spectres transmitted and received are related to the variations in both temperature and strain, commercial FBG sensors were opportunely modified and calibrated. The optical fibers were hooked to the fibers entering into the injection pultrusion die. Taking the pulling speed into account, each waveform acquired was correlated to a position within the die. Obtained data highlight the effect of the heat generation due to resin reaction as well as longitudinal strains related to the pulling force, the thermal expansion and the chemical shrinkage of the resin system.

  1. Measurement of agglomerate strength distributions in agglomerated powders

    International Nuclear Information System (INIS)

    Ciftcioglu, M.; Aking, M.; Burkhart, L.

    1986-01-01

    Strength distributions of particle agglomerates in six different yttria powders were measured using a calibrated ultrasonic sound field. The density of sintered pellets was directly related to the agglomerate strength of each powder. No systematic relation to the sintered density was observed for bulk densities or pressure-density compaction data for the loose powders, or for pore size distributions or green densities for the pressed compacts

  2. Indirect deformation (strain) measurements and calibrations in Sandia triaxial apparatus for rock testing to 2500C

    International Nuclear Information System (INIS)

    Wawersik, W.R.

    1979-09-01

    Indirect procedures for axial and radial strain measurements on rock in triaxial tests to 250 0 C are presented. The description of techniques includes discussions of all calibrations and of the accuracies of measurements. In addition, two examples are given to show how the techniques are implemented in triaxial compression and triaxial extension experiments. 10 figures

  3. Measurement of spatial dose-rate distribution using a position sensitive detector

    International Nuclear Information System (INIS)

    Emoto, T.; Torii, T.; Nozaki, T.; Ando, H.

    1994-01-01

    Recently, the radiation detectors using plastic scintillation fibers (PSF) have been developed to measure the positions exposed to radiation such as neutrons and high energy charged particles. In particular, the time of flight (TOF) method for measuring the difference of time that two directional signals of scintillation light reach both ends of a PSF is a rather simple method for the measurement of the spatial distribution of fast neutron fluence rate. It is possible to use the PSF in nuclear facility working areas because of its flexibility, small diameter and long length. In order to apply TOF method to measure spatial gamma dose rate distribution, the characteristic tests of a detector using PSFs were carried out. First, the resolution of irradiated positions and the counting efficiency were measured with collimated gamma ray. The sensitivity to unit dose rate was also obtained. The measurement of spatial dose rate distribution was also carried out. The sensor is made of ten bundled PSFs, and the experimental setup is described. The experiment and the results are reported. It was found that the PSF detector has the good performance to measure spatial gamma dose rate distribution. (K.I.)

  4. Simultaneous resonant x-ray diffraction measurement of polarization inversion and lattice strain in polycrystalline ferroelectrics

    DEFF Research Database (Denmark)

    Gorfman, S.; Simons, Hugh; Iamsasri, T.

    2016-01-01

    and strain in ferroelectrics is an ongoing challenge that so far has obscured its fundamental behaviour. By utilizing small intensity differences between Friedel pairs due to resonant scattering, we demonstrate a time-resolved X-ray diffraction technique for directly and simultaneously measuring both lattice...

  5. Coupled stress-strain and electrical resistivity measurements on copper based shape memory single crystals

    Directory of Open Access Journals (Sweden)

    Gonzalez Cezar Henrique

    2004-01-01

    Full Text Available Recently, electrical resistivity (ER measurements have been done during some thermomechanical tests in copper based shape memory alloys (SMA's. In this work, single crystals of Cu-based SMA's have been studied at different temperatures to analyse the relationship between stress (s and ER changes as a function of the strain (e. A good consistency between ER change values is observed in different experiments: thermal martensitic transformation, stress induced martensitic transformation and stress induced reorientation of martensite variants. During stress induced martensitic transformation (superelastic behaviour and stress induced reorientation of martensite variants, a linear relationship is obtained between ER and strain as well as the absence of hys teresis. In conclusion, the present results show a direct evidence of martensite electrical resistivity anisotropy.

  6. Properties of strain gages at cryogenic temperature

    International Nuclear Information System (INIS)

    Shibata, Nobuo; Fujiyoshi, Toshimitsu.

    1978-01-01

    At the time of developing superconduction generators, the stress measurement for rotor parts is required to grasp the safety and performance of the rotor at cryogenic temperature, which is cooled with liquid helium. In case of carrying out the stress measurement with strain gages, the problems are as follows. The strain gages and lead wires are exposed to cryogenic temperature from 4 to 10 K and strong magnetic field of about 3T, and subjected to high centrifugal acceleration of about 500G. In order to establish the techniques of the stress measurement under such conditions, the adhesives and damp-proof coatings for strain gages and strain gages themselves in Japan and foreign countries were examined on the properties at cryogenic temperature. As for the properties of strain gages, mainly the apparent strain owing to temperature change was investigated, and the change of the gage factors was studies only at liquid nitrogen temperature. The stress measurement with strain gages at low temperature had been studied in detail down to liquid nitrogen temperature concerning LNG tanks. The experimental apparatus, the samples, the testing methods and the test results of cooling tests on adhesives and damp-proof coatings, and the temperature characteristics of strain gages are reported. The usable adhesives and coatings were found, and correction by accurate temperature measurement is required for apparent strain. (Kako, I.)

  7. Annealing Behavior of Nanostructured Aluminum Produced by Cold Rolling to Ultrahigh Strains

    DEFF Research Database (Denmark)

    Cao, W.Q.; Godfrey, A.; Hansen, Niels

    2009-01-01

    The isochronal annealing behavior of nanostructured commercial purity aluminum (AA1100 and AA1200) produced by either cold rolling (CR) or accumulative roll bonding (ARB) up to ultrahigh strains of about 99.5 pct reduction in thickness has been studied in the temperature range from 200 degrees C...... to 420 degrees C. Microstructural and texture measurements were made using data from electron backscatter diffraction (EBSD) investigations, and the change in mechanical strength was followed using hardness measurements. A large effect of the rolling strain is observed on recovery at temperatures below...... for analyzing the uniformity of the structural coarsening, based on analysis of the crystallite size distribution with respect to the mode, is described. The analysis demonstrates that annealing leads to locally nonuniform changes in the microstructure, and to a description of the annealing process...

  8. Light distribution in leaf chambers and its consequences for photosynthesis measurements

    NARCIS (Netherlands)

    Hogewoning, S.W.; Trouwborst, G.; Harbinson, J.; Ieperen, van W.

    2010-01-01

    The impact of a heterogeneous distribution of actinic light within a leaf chamber for photosynthetic measurements by gas exchange on the photosynthesis-irradiance relationship was investigated. High-resolution light distributions were measured over the area of a commercially available clamp-on leaf

  9. STRAIN LOCALIZATION PECULIARITIES AND DISTRIBUTION OF ACOUSTIC EMISSION SOURCES IN ROCK SAMPLES TESTED BY UNIAXIAL COMPRESSION AND EXPOSED TO ELECTRIC PULSES

    Directory of Open Access Journals (Sweden)

    V. A. Mubassarova

    2014-01-01

    accumulation of defects. The location system can be effectively applied when events with high amplitudes are accumulated in sufficient number. In this regard, clustering of AE sources (defects in the area of a future fault was recorded only during the measuring test when the AE activity was quite high at the constant load.As shown by data from the optical diagnostics set of equipment, LаVision Strain Master System, deformation of a specimen takes place in a non-uniform pattern over its surface, which is manifested as consecutively propagating waves of localized strain. This conclusion contributes to the research results obtained earlier for rock samples under tension and compression [Panteleev et al., 2013b, 2013c, 2013d]. Localized axial strain waves and localized radial strain waves (when material particles move in the direction perpendicular to the compression direction are concurrently observed. Such localized strain waves are ‘slow’ – they propagate at velocities that are by six or seven orders lower than the intrinsic velocity of sound propagation in the material. This observation correlates with the research results obtained earlier in studies of strain localization forms in the course of rock deformation [Zuev, 2011; Zuev et al., 2012].When the loaded specimen is impacted by the electromagnetic field, maximum strain values are slightly decreased in comparison with those in the ordinary case (when only compressive load is applied. This trend seems to be a specific feature of changes in localization of deformation in the loaded rock samples impacted by electric pulses. Besides, the experiments demonstrate that a source of macro-destruction can be induced by the influence of an external electromagnetic field, and the growth of a nucleus of such source can be stabilized during the impact. The above conclusions correlate with the statistical model of a solid body with defects which is developed in ICMM [Panteleev et al., 2011, 2012, 2013a].

  10. Internally Mounting Strain Gages

    Science.gov (United States)

    Jett, J. R., Jr.

    1984-01-01

    Technique for mounting strain gages inside bolt or cylinder simultaneously inserts gage, attached dowel segment, and length of expandable tubing. Expandable tubing holds gage in place while adhesive cures, assuring even distribution of pressure on gage and area gaged.

  11. A method to measure depth distributions of implanted ions

    International Nuclear Information System (INIS)

    Arnesen, A.; Noreland, T.

    1977-04-01

    A new variant of the radiotracer method for depth distribution determinations has been tested. Depth distributions of radioactive implanted ions are determined by dissolving thin, uniform layers of evaporated material from the surface of a backing and by measuring the activity before and after the layer removal. The method has been used to determine depth distributions for 25 keV and 50 keV 57 Co ions in aluminium and gold. (Auth.)

  12. Apparatus for power and breeding distribution measurements in breeder reactors

    International Nuclear Information System (INIS)

    Goldstein, N.P.; Sun, K.H.

    1975-01-01

    A detection system is disclosed herein for the measurement of power and breeding distribution inside a breeder reactor. Small diameter BeO balls comprising oxides of 235 U and 238 U are inserted into the reactor for activation and withdrawn to be counted in a Ge(Li) counter. Measurements of the activated fission and 239 Np gamma rays yield the desired distributions. (Official Gazette)

  13. Strain-tuned optoelectronic properties of hollow gallium sulphide microspheres

    Science.gov (United States)

    Zhang, Yin; Chen, Chen; Liang, C. Y.; Liu, Z. W.; Li, Y. S.; Che, Renchao

    2015-10-01

    Sulfide semiconductors have attracted considerable attention. The main challenge is to prepare materials with a designable morphology, a controllable band structure and optoelectronic properties. Herein, we report a facile chemical transportation reaction for the synthesis of Ga2S3 microspheres with novel hollow morphologies and partially filled volumes. Even without any extrinsic dopant, photoluminescence (PL) emission wavelength could be facilely tuned from 635 to 665 nm, depending on its intrinsic inhomogeneous strain distribution. Geometric phase analysis (GPA) based on high-resolution transmission electron microscopy (HRTEM) imaging reveals that the strain distribution and the associated PL properties can be accurately controlled by changing the growth temperature gradient, which depends on the distance between the boats used for raw material evaporation and microsphere deposition. The stacking-fault density, lattice distortion degree and strain distribution at the shell interfacial region of the Ga2S3 microspheres could be readily adjusted. Ab initio first-principles calculations confirm that the lowest conductive band (LCB) is dominated by S-3s and Ga-4p states, which shift to the low-energy band as a result of the introduction of tensile strain, well in accordance with the observed PL evolution. Therefore, based on our strain driving strategy, novel guidelines toward the reasonable design of sulfide semiconductors with tunable photoluminescence properties are proposed.Sulfide semiconductors have attracted considerable attention. The main challenge is to prepare materials with a designable morphology, a controllable band structure and optoelectronic properties. Herein, we report a facile chemical transportation reaction for the synthesis of Ga2S3 microspheres with novel hollow morphologies and partially filled volumes. Even without any extrinsic dopant, photoluminescence (PL) emission wavelength could be facilely tuned from 635 to 665 nm, depending on its

  14. Effect of Attachment Type on Denture Strain in Maxillary Implant Overdentures: Part 1. Overdenture with Palate.

    Science.gov (United States)

    Takahashi, Toshihito; Gonda, Tomoya; Maeda, Yoshinobu

    This study examined the effects of attachments on strain in maxillary implant overdentures supported by two or four implants. A maxillary edentulous model with implants inserted into anterior, premolar, and molar areas was fabricated, and three types of unsplinted attachments-ball, locator, and magnet-were set on the implants distributed under various conditions. Maxillary experimental dentures were fabricated, and two strain gauges were attached at the anterior midline on the labial and palatal sides. A vertical occlusal load of 98 N was applied and shear strain of the dentures was measured. On both sides, magnet attachments resulted in the lowest shear strain, while ball attachments resulted in the highest shear strain under most conditions. However, differences in shear strain among the three attachment types were not significant when supported by four implants, especially molar implants. Shear strain of the maxillary implant overdenture was lowest when using magnet attachments. Magnet attachments mounted on four implants are recommended to prevent denture complications when using maxillary implant overdentures.

  15. Measurement of neutron flux distribution by semiconductor detector

    International Nuclear Information System (INIS)

    Obradovic, D.; Bosevski, T.

    1964-01-01

    Application of semiconductor detectors for measuring neutron flux distribution is about 10 times faster than measurements by activation foils and demands significantly lower reactor power. Following corrections are avoided: mass of activation foils which influences the self shielding, nuclear decay during activity measurements; counter dead-time. It is possible to control the measured data during experiment and repeat measurements if needed. Precision of the measurement is higher since it is possible to choose the wanted statistics. The method described in this paper is applied for measurements at the RB reactor. It is concluded that the method is suitable for fast measurements but the activation analysis is still indispensable

  16. Ion Distribution Measurement In Plasma Focus

    International Nuclear Information System (INIS)

    Suryadi; Sunardi; Usada, Widdi; Purwadi, Agus; Zaenuri, Akhmad

    1996-01-01

    Measurement of the Argon ion distribution in plasma focus by using Faraday cup has been done. The intensity of ion beam followed the I Rn rule, n=1,02. In the operation condition of 0,8 mbar and 12,5 kV the current sheath spen 2.2 to 2.4 μsecond in the rundown phase. Cu ion was also been observed in the Faraday cup

  17. A new kind of droplet space distribution measuring method

    International Nuclear Information System (INIS)

    Ma Chao; Bo Hanliang

    2012-01-01

    A new kind of droplet space distribution measuring technique was introduced mainly, and the experimental device which was designed for the measuring the space distribution and traces of the flying film droplet produced by the bubble breaking up near the free surface of the water. This experiment was designed with a kind of water-sensitivity test paper (rice paper) which could record the position and size of the colored scattering droplets precisely. The rice papers were rolled into cylinders with different diameters by using tools. The bubbles broke up exactly in the center of the cylinder, and the space distribution and the traces of the droplets would be received by analysing all the positions of the droplets produced by the same size bubble on the rice papers. (authors)

  18. Measurement of the thermal flux distribution in the IEA-R1 reactor

    International Nuclear Information System (INIS)

    Tangari, C.M.; Moreira, J.M.L.; Jerez, R.

    1986-01-01

    The knowledge of the neutron flux distribution in research reactors is important because it gives the power distribution over the core, and it provides better conditions to perform experiments and sample irradiations. The measured neutron flux distribution can also be of interest as a means of comparison for the calculational methods of reactor analysis currently in use at this institute. The thermal neutron flux distribution of the IEA-R1 reactor has been measured with the miniature chamber WL-23292. For carrying out the measurements, it was buit a guide system that permit the insertion of the mini-chamber i between the fuel of the fuel elements. It can be introduced in two diferent positions a fuel element and in each it spans 26 axial positions. With this guide system the thermal neutron flux distribution of the IEA-R1 nuclear reactor can be obtained in a fast and efficient manner. The element measured flux distribution shows clearly the effects of control rods and reflectors in the IEA-R1 reactor. The difficulties encountered during the measurements are mentioned with detail as well as the procedures adopteed to overcome them. (Author) [pt

  19. The development of an enhanced strain measurement device to support testing of radioactive material packages

    International Nuclear Information System (INIS)

    Uncapkher, W.L.; Arviso, M.

    1995-01-01

    Radioactive material package designers use structural testing to verify and demonstrate package performance. A major part of evaluating structural response is the collection of reliable instrumentation measurement data. Over the last four decades, Sandia National Laboratories (SNL) has been actively involved in the development, testing, and evaluation of measurement devices for a broad range of applications, resulting in the commercialization of several measurement devices commonly used today. SNL maintains an ongoing program sponsored by the US Department of Energy (DOE) to develop and evaluate measurement devices to support testing of packages used to transport radioactive or hazardous materials. The development of the enhanced strain measurement device is part of this program

  20. Problems in use and security of measurement of high temperature strain gages at various temperature limits up to 10000C

    International Nuclear Information System (INIS)

    Ziegler, K.

    1982-01-01

    The examples given show the quality and use of manufacturers' data for a series of behaviour criteria for strain gages in the high temperature region. These results should not only be regarded critically. The manufacturer must appreciate that the very costly programme of investigations on the users' side represents a product development for large parts for the manufacturer of the strain gauges. It would therefore be desirable if these considerations were to initiate investigations on the manufacturer's part, in order to clear up the problematic are of the use of strain gages in the high temperature field, in order to provide the customer with more reliable and better strain gage characteristics for very expensive high temperature strain measurements. (orig.) [de

  1. Temperature measurement distributed on a building by fiber optic BOTDA sensor

    International Nuclear Information System (INIS)

    Kwon, Il Bum; Kim, Chi Yeop; Choi, Man Yong; Lee, Seung Seok

    2002-01-01

    We have focused on the development of a fiber optic BOTDA (Brillouin Optical Time Domain Analysis) sensor system in order to measure temperature distributed on large structures. Also, we present a feasibility study of the fiber optic sensor to monitor the distributed temperature on a building construction. A fiber optic BOTDA sensor system, which has a capability of measuring the temperature distribution, attempted over several kilometers of long fiber paths. This simple fiber optic sensor system employs a laser diode and two electro-optic modulators. The optical fiber of the length of 1400 m was installed on the surfaces of the building. The change of the distributed temperature on the building construction was well measured by this fiber optic sensor. The temperature changed normally up to 4 degrees C through one day.

  2. Strain transfer analysis of optical fiber based sensors embedded in an asphalt pavement structure

    International Nuclear Information System (INIS)

    Wang, Huaping; Xiang, Ping

    2016-01-01

    Asphalt pavement is vulnerable to random damage, such as cracking and rutting, which can be proactively identified by distributed optical fiber sensing technology. However, due to the material nature of optical fibers, a bare fiber is apt to be damaged during the construction process of pavements. Thus, a protective layer is needed for this application. Unfortunately, part of the strain of the host material is absorbed by the protective layer when transferring the strain to the sensing fiber. To account for the strain transfer error, in this paper a theoretical analysis of the strain transfer of a three-layered general model has been carried out by introducing Goodman’s hypothesis to describe the interfacial shear stress relationship. The model considers the viscoelastic behavior of the host material and protective layer. The effects of one crack in the host material and the sensing length on strain transfer relationship are been discussed. To validate the effectiveness of the strain transfer analysis, a flexible asphalt-mastic packaged distributed optical fiber sensor was designed and tested in a laboratory environment to monitor the distributed strain and appearance of cracks in an asphalt concrete beam at two different temperatures. The experimental results indicated that the developed strain transfer formula can significantly reduce the strain transfer error, and that the asphalt-mastic packaged optical fiber sensor can successfully monitor the distributed strain and identify local cracks. (paper)

  3. Strain transfer analysis of optical fiber based sensors embedded in an asphalt pavement structure

    Science.gov (United States)

    Wang, Huaping; Xiang, Ping

    2016-07-01

    Asphalt pavement is vulnerable to random damage, such as cracking and rutting, which can be proactively identified by distributed optical fiber sensing technology. However, due to the material nature of optical fibers, a bare fiber is apt to be damaged during the construction process of pavements. Thus, a protective layer is needed for this application. Unfortunately, part of the strain of the host material is absorbed by the protective layer when transferring the strain to the sensing fiber. To account for the strain transfer error, in this paper a theoretical analysis of the strain transfer of a three-layered general model has been carried out by introducing Goodman’s hypothesis to describe the interfacial shear stress relationship. The model considers the viscoelastic behavior of the host material and protective layer. The effects of one crack in the host material and the sensing length on strain transfer relationship are been discussed. To validate the effectiveness of the strain transfer analysis, a flexible asphalt-mastic packaged distributed optical fiber sensor was designed and tested in a laboratory environment to monitor the distributed strain and appearance of cracks in an asphalt concrete beam at two different temperatures. The experimental results indicated that the developed strain transfer formula can significantly reduce the strain transfer error, and that the asphalt-mastic packaged optical fiber sensor can successfully monitor the distributed strain and identify local cracks.

  4. Distributed collaborative team effectiveness: measurement and process improvement

    Science.gov (United States)

    Wheeler, R.; Hihn, J.; Wilkinson, B.

    2002-01-01

    This paper describes a measurement methodology developed for assessing the readiness, and identifying opportunities for improving the effectiveness, of distributed collaborative design teams preparing to conduct a coccurent design session.

  5. A Review of Hybrid Fiber-Optic Distributed Simultaneous Vibration and Temperature Sensing Technology and Its Geophysical Applications

    Directory of Open Access Journals (Sweden)

    Khalid Miah

    2017-11-01

    Full Text Available Distributed sensing systems can transform an optical fiber cable into an array of sensors, allowing users to detect and monitor multiple physical parameters such as temperature, vibration and strain with fine spatial and temporal resolution over a long distance. Fiber-optic distributed acoustic sensing (DAS and distributed temperature sensing (DTS systems have been developed for various applications with varied spatial resolution, and spectral and sensing range. Rayleigh scattering-based phase optical time domain reflectometry (OTDR for vibration and Raman/Brillouin scattering-based OTDR for temperature and strain measurements have been developed over the past two decades. The key challenge has been to find a methodology that would enable the physical parameters to be determined at any point along the sensing fiber with high sensitivity and spatial resolution, yet within acceptable frequency range for dynamic vibration, and temperature detection. There are many applications, especially in geophysical and mining engineering where simultaneous measurements of vibration and temperature are essential. In this article, recent developments of different hybrid systems for simultaneous vibration, temperature and strain measurements are analyzed based on their operation principles and performance. Then, challenges and limitations of the systems are highlighted for geophysical applications.

  6. A Review of Hybrid Fiber-Optic Distributed Simultaneous Vibration and Temperature Sensing Technology and Its Geophysical Applications.

    Science.gov (United States)

    Miah, Khalid; Potter, David K

    2017-11-01

    Distributed sensing systems can transform an optical fiber cable into an array of sensors, allowing users to detect and monitor multiple physical parameters such as temperature, vibration and strain with fine spatial and temporal resolution over a long distance. Fiber-optic distributed acoustic sensing (DAS) and distributed temperature sensing (DTS) systems have been developed for various applications with varied spatial resolution, and spectral and sensing range. Rayleigh scattering-based phase optical time domain reflectometry (OTDR) for vibration and Raman/Brillouin scattering-based OTDR for temperature and strain measurements have been developed over the past two decades. The key challenge has been to find a methodology that would enable the physical parameters to be determined at any point along the sensing fiber with high sensitivity and spatial resolution, yet within acceptable frequency range for dynamic vibration, and temperature detection. There are many applications, especially in geophysical and mining engineering where simultaneous measurements of vibration and temperature are essential. In this article, recent developments of different hybrid systems for simultaneous vibration, temperature and strain measurements are analyzed based on their operation principles and performance. Then, challenges and limitations of the systems are highlighted for geophysical applications.

  7. [Enterotoxin genes occurance among S. aureus strains isolated from inpatients and carriers].

    Science.gov (United States)

    Lawrynowicz-Paciorek, Maja; Kochman, Maria; Piekarska, Katarzyna; Wyrebiak, Agata; Potracka, Ewa; Leniak-Chmiel, Urszula; Magdziak, Agnieszka

    2006-01-01

    We examined 44 inpatients and 66 carriers Staphylococcus aureus strains, isolated in years 2002-2005, for the presence of 18 enterotoxin genes (se/sel) (by PCR), the ability for A-D enterotoxin production (by SET-RPLA) and antibiotic resistance distribution (by disc diffusion method). se/sel genes were detected in 90,9% of all strains, sea (70,5%) and selk and selq (52,3%) - among inpatients strains and egc (65,2%) - among carriers strains were the most frequently se/sel genes found. Positive results of SET-RPLA were consistent with PCR results. There was no correlation observed between antibiotic resistance and se/sel genes distribution among tested S. aureus strains.

  8. MODERNIZATION OF GENEOTIPING OF STRAINS B. PERTUSSIS

    Directory of Open Access Journals (Sweden)

    G. A. Ivashinnikova

    2013-01-01

    Full Text Available The new rapid molecular genotyping method was developed for studying the structure of ptxP promoter of pertussis toxin. Method is based on PCR-RFLP analysis, which allows studying the specific restriction profiles of the B. pertussis strains and allows differentiation of the strains with the ptxP structural particularities. The developed method for genotyping of strains of B. pertussis can be hhelpful when monitoring strains of the causative agent of whooping cough in system of an epidemiological surveillance over pertussis infections, allowing observation over circulating population of B.pertussis, revealing strains of the causative agent of whooping cough with high production of pertussis toxin and to watch their distribution.

  9. Fiber optic strain measurements using an optically-active polymer

    Science.gov (United States)

    Buckley, Leonard J.; Neumeister, Gary C.

    1992-03-01

    A study encompassing the use of an optically-active polymer as the strain-sensing medium in an organic matrix composite was performed. Several compounds were synthesized for use as the inner cladding material for silica fiber-optic cores. These materials include a diacetylene containing polyamide. It is possible to dynamically modify the optical properties of these materials through changes in applied strain or temperature. By doing so the characteristic absorption in the visible is reversibly shifted to a higher energy state. The polymer-coated fiber-optic cores were initially studied in epoxy resin. Additionally, one of the polyamide/diacetylene polymers was studied in a spin-fiber form consisting of 15 micron filaments assembled in multifilament tows. The most promising configuration and materials were then investigated further by embedding in graphite/epoxy composite laminates. In each case the shift in the visible absorption peak was monitored as a function of applied mechanical strain.

  10. Corrosion Measurements in Reinforced Fly Ash Concrete Containing Steel Fibres Using Strain Gauge Technique

    Directory of Open Access Journals (Sweden)

    V. M. Sounthararajan

    2013-01-01

    Full Text Available Corrosion of steel bars in concrete is a serious problem leading to phenomenal volume expansion and thereby leading to cover concrete spalling. It is well known that the reinforced concrete structures subjected to chloride attack during its service life cause these detrimental effects. The early detection of this damage potential can extend the service life of concrete. This study reports the comprehensive experimental studies conducted on the identification of corrosion mechanism in different types of reinforced concrete containing class-F fly ash and hooked steel fibres. Fly ash replaced concrete mixes were prepared with 25% and 50% fly ash containing steel fibres at 0.5%, 1.0%, and 1.5% by volume fraction. Corrosion process was investigated in an embedded steel bar (8 mm diameter reinforced in concrete by passing an impressed current in sodium chloride solution. Strain gauge attached to the rebars was monitored for electrical measurements using strain conditioner. Strain gauge readings observed during the corrosion process exhibited the volume changes of the reinforcement embedded inside the concrete. The corrosion potential of different steel fibre reinforced concrete mixes with fly ash addition showed higher resistance towards the corrosion initiation.

  11. Distributed optical fibre sensing for early detection of shallow landslides triggering.

    Science.gov (United States)

    Schenato, Luca; Palmieri, Luca; Camporese, Matteo; Bersan, Silvia; Cola, Simonetta; Pasuto, Alessandro; Galtarossa, Andrea; Salandin, Paolo; Simonini, Paolo

    2017-10-31

    A distributed optical fibre sensing system is used to measure landslide-induced strains on an optical fibre buried in a large scale physical model of a slope. The fibre sensing cable is deployed at the predefined failure surface and interrogated by means of optical frequency domain reflectometry. The strain evolution is measured with centimetre spatial resolution until the occurrence of the slope failure. Standard legacy sensors measuring soil moisture and pore water pressure are installed at different depths and positions along the slope for comparison and validation. The evolution of the strain field is related to landslide dynamics with unprecedented resolution and insight. In fact, the results of the experiment clearly identify several phases within the evolution of the landslide and show that optical fibres can detect precursory signs of failure well before the collapse, paving the way for the development of more effective early warning systems.

  12. Characterization of plastic strains and crystallographic properties surrounding defects in steam generator tubes by orientation imaging microscopy

    International Nuclear Information System (INIS)

    Lehockey, E.M.; Brennenstuhl, A.M.

    2002-01-01

    Orientation Imaging Microscopy (OIM) has become a valuable technique for characterizing grain boundary structure, texture, and grain size distribution, which govern material susceptibility to degenerative effects (e.g. IGSCC). Methods recently developed, by Kinectrics, have extended OIM capabilities toward mapping and quantifying residual plastic strains in materials. OIM is applied in the present work to characterize the distribution of plastic strains, that accumulate in CANDU steam generator tubing during installation and service potentially undermining the performance, reliability, and fitness-for-service of these components. Plastic strain that evolves in response to roller-expansion was characterized in simulated roll joints constructed from Alloy 600 tubing. Results underscore the effect of over-rolling in generating intense gradients with broad variations in strain that extend significant distances through the wall thickness. Of greater relevance is the orientation of these gradients in the transverse direction, relative to the tube axis and potential for the development of abnormal grain growth during post-expansion heat treatments. The magnitude and distribution of strain measured by OIM are remarkably consistent with Finite Element Analysis (FEA) predictions offering compelling evidence as to the reliability of the OIM technique. OIM offers superior resolution than can be practically achieved with FEA having particular relevance in identifying highly localized concentrations of strain surrounding metallurgical defects that can serve as precursors to stress-related degenerative effects (e.g. IGSCC). The spatial distribution of residual plastic strain was also characterized within the context of localized texture, and grain size morphology surrounding (OD) 'pits' and indentations found in ex-service Monel 400 and Alloy 800 SG tubes, respectively. An absence of strain surrounding these surface defects suggests their propensity for promoting more deleterious

  13. Gravity-dependent ventilation distribution in rats measured with electrical impedance tomography

    International Nuclear Information System (INIS)

    Rooney, Daniel; Fraser, John F; R Dunster, Kimble; Schibler, Andreas; Friese, Marlies

    2009-01-01

    Ventilation in larger animals and humans is gravity dependent and mainly distributed to the dependent lung. Little is known of the effect of gravity on ventilation distribution in small animals such as rodents. The aim of this study was to investigate gravity-dependent ventilation distribution and regional filling characteristics in rats. Ventilation distribution and regional lung filling were measured in six rats using electrical impedance tomography (EIT). Measurements were performed in four body positions (supine, prone, left and right lateral), and all animals were ventilated with increasing tidal volumes from 3 to 8 mL kg −1 . The effect of gravity on regional ventilation distribution was assessed with profiles of relative impedance change and calculation of the geometric centre. Regional filling was measured by calculating the slope of the plot of regional versus global relative impedance change on a breath-by-breath basis. Ventilation was significantly distributed to the non-dependent lung regardless of body position and tidal volume used. The geometric centre was located in the dependent lung in all but prone position. The regional filling characteristics followed an anatomical pattern with the posterior and the right lung generally filling faster. Gravity had little impact on regional filling. Ventilation distribution in rats is gravity dependent, whereas regional filling characteristics are dependent on anatomy

  14. Measuring distributed leadership agency in a hospital context.

    Science.gov (United States)

    Jønsson, Thomas; Unterrainer, Christine; Jeppesen, Hans-Jeppe; Jain, Ajay Kumar

    2016-09-19

    Purpose The purpose of this paper is to develop and validate an instrument that can measure distributed leadership (DL) as employees' active participation in DL tasks. The authors designate this as the distributed leadership agency (DLA). Design/methodology/approach Data were collected throughout all departments and occupational groups at a merged centralized hospital setting in Denmark. A total of 1,774 employees from 24 hospital departments and 16 occupational groups completed our survey. Structural equation model and confirmatory factor analyses were applied to identify appropriate items and a test for measurement invariance, predictive, discriminant and convergent validity, and ANOVAs were applied to analyse group differences in DLA. Findings The identified unidimensional questionnaire consists of seven items, as it is different from, but associated with, empowering leadership, organizational influence, attitude to participation and trust in management. As theoretically predicted, DLA is positively related to self-efficacy, job satisfaction and innovative behaviour. Chief physicians, permanent employees and employee representatives scored higher on the scale than the rest of their respective counterparts. Practical implications The survey offers a method to assess a distribution of leadership agency in hospital organizations. Such assessment may provide a basis for organizational and leadership development. Originality/value The present study provides a reliable and valid quantitative instrument that measures how much employees at all hierarchical levels are involved in concrete leadership activities in the hospital context. Taking a normative perspective the authors could show that DL - measured with the DLA-questionnaire - has positive effects on employees' behaviour.

  15. Strain expansion-reduction approach

    Science.gov (United States)

    Baqersad, Javad; Bharadwaj, Kedar

    2018-02-01

    Validating numerical models are one of the main aspects of engineering design. However, correlating million degrees of freedom of numerical models to the few degrees of freedom of test models is challenging. Reduction/expansion approaches have been traditionally used to match these degrees of freedom. However, the conventional reduction/expansion approaches are only limited to displacement, velocity or acceleration data. While in many cases only strain data are accessible (e.g. when a structure is monitored using strain-gages), the conventional approaches are not capable of expanding strain data. To bridge this gap, the current paper outlines a reduction/expansion technique to reduce/expand strain data. In the proposed approach, strain mode shapes of a structure are extracted using the finite element method or the digital image correlation technique. The strain mode shapes are used to generate a transformation matrix that can expand the limited set of measurement data. The proposed approach can be used to correlate experimental and analytical strain data. Furthermore, the proposed technique can be used to expand real-time operating data for structural health monitoring (SHM). In order to verify the accuracy of the approach, the proposed technique was used to expand the limited set of real-time operating data in a numerical model of a cantilever beam subjected to various types of excitations. The proposed technique was also applied to expand real-time operating data measured using a few strain gages mounted to an aluminum beam. It was shown that the proposed approach can effectively expand the strain data at limited locations to accurately predict the strain at locations where no sensors were placed.

  16. Whole-Genome Sequences of Four Strains Closely Related to Members of the Mycobacterium chelonae Group, Isolated from Biofilms in a Drinking Water Distribution System Simulator

    Science.gov (United States)

    We report the draft genome sequences of four Mycobacterium chelonae group strains from biofilms obtained after a ‘chlorine burn’ in a chloraminated drinking water distribution system simulator. These opportunistic pathogens have been detected in drinking and hospital water distr...

  17. Mechanically Strain-Induced Modification of Selenium Powders in the Amorphization Process

    International Nuclear Information System (INIS)

    Fuse, Makoto; Shirakawa, Yoshiyuki; Shimosaka, Atsuko; Hidaka, Jusuke

    2003-01-01

    For the fabrication of particles designed in the nanoscale structure, or the nanostructural modification of particles using mechanical grinding process, selenium powders ground by a planetary ball mill at various rotational speeds have been investigated. Structural analyses, such as particle size distributions, crystallite sizes, lattice strains and nearest neighbour distances were performed using X-ray diffraction, scanning electron microscopy and dynamical light scattering.By grinding powder particles became spherical composites consisting of nanocrystalline and amorphous phase, and had a distribution with the average size of 2.7 μm. Integral intensities of diffraction peaks of annealed crystal selenium decreased with increasing grinding time, and these peaks broadened due to lattice strains and reducing crystallite size during the grinding. The ground powder at 200 rpm did not have the lattice strain and showed amorphization for the present grinding periods. It indicates that the amorphization of Se by grinding accompanies the lattice strain, and the lattice strain arises from a larger energy concerning intermolecular interaction. In this process, the impact energy is spent on thermal and structural changes according to energy accumulation in macroscopic (the particle size distribution) and microscopic (the crystallite size and the lattice strain) range

  18. Study on the stress and strain during welding of plate-to-pipe joint

    Energy Technology Data Exchange (ETDEWEB)

    Na, S.J.; Kim, H.W.

    1986-09-01

    In manufacturing of pipe walls for boiler units, distortion can result in pipe-to-pipe joints from the nonuniform expansion and contraction of the weld metal and the adjacent base metal during heating and cooling cycle of the welding process. In this study, the stresses and strains during longitudinal welding of the plate-to-pipe joint were investigated. Using the method of sucessive elastic solution, longitudinal stresses and strains during and after welding were calculated from the information of temperature distributions obtained by Rosenthal's equations. In order to confirm the validity of the numerical results, the temperature and residual stress distributions were measured and compared with the calculated results. In spite of some assumptions, the one-dimensional analytical results of residual stresses were in fairly good agreement with the experimental ones. The residual stresses due to welding of plate-to-pipe joints are tensile near the weld line and compressive in the base metal as in the welding of plates. The amount and distribution of residual stresses were deeply dependent on the heat input ratio of the plate and pipe.

  19. Optimal distribution of integration time for intensity measurements in Stokes polarimetry.

    Science.gov (United States)

    Li, Xiaobo; Liu, Tiegen; Huang, Bingjing; Song, Zhanjie; Hu, Haofeng

    2015-10-19

    We consider the typical Stokes polarimetry system, which performs four intensity measurements to estimate a Stokes vector. We show that if the total integration time of intensity measurements is fixed, the variance of the Stokes vector estimator depends on the distribution of the integration time at four intensity measurements. Therefore, by optimizing the distribution of integration time, the variance of the Stokes vector estimator can be decreased. In this paper, we obtain the closed-form solution of the optimal distribution of integration time by employing Lagrange multiplier method. According to the theoretical analysis and real-world experiment, it is shown that the total variance of the Stokes vector estimator can be significantly decreased about 40% in the case discussed in this paper. The method proposed in this paper can effectively decrease the measurement variance and thus statistically improves the measurement accuracy of the polarimetric system.

  20. Interpreting strain measurements when drilling anisotropic rocks: return of experience from using CSIRO cells in Tournemire argillite

    International Nuclear Information System (INIS)

    Ben Ouanas, Abdelmonem

    2010-01-01

    In Geomechanics, determining the state of stress and the rheology of rock massif can be obtained by measuring the strain response of the ground under the effect of a known stress. A method among others is to use a cell integrated (with strain gauges oriented in different directions) installed in a borehole and secured to the mass through an epoxy glue. This measurement is used, notably, to determine the stress state in situ by the 'overcoring' method and the elastic parameters of the rock from the 'biaxial' test. Between November 2005 and January 2006, a geomechanical testing campaign was conducted in the argillaceous formation of the Tournemire experimental site (Aveyron, France) using CSIRO Hi cells. The strain measurements obtained during overcoring and biaxial tests have shown unusual phenomena, which have made difficult the determination of anisotropic elastic parameters of the rock and the access to the site stress. Therefore, through researches for explanations of the origin of these phenomena, this thesis aimed to improve and contribute to the understanding of the Tournemire argillite behaviour and to upgrade the measurement protocol as well as the interpretation of cells CSIRO's strain. The approach was, firstly, to issue a number of hypotheses to explain certain phenomena observed in literature. In a second step, these hypotheses were tested through analytical and numerical modelling of the biaxial and overcoring tests then through the realization of new experiments in situ within laboratory on argillite, and also on materials tests (cement, sample of glue). It is concluded that the unusual phenomena observed are essentially the result of the conditions for implementing in situ CSIRO's cell. The study particularly focused on the artefacts induced by the visco-plastic behaviour of the epoxy glue when it is incompletely polymerised. The role of damage on the rock generated by drilling operations is also discussed. Some practical recommendations for

  1. Measurement of size distribution for 220Rn progeny attached aerosols

    International Nuclear Information System (INIS)

    Zhang Lei; Guo Qiuju; Zhuo Weihai

    2008-01-01

    The size distribution of radioactive aerosols is a very important factor for evaluating the inner exposure dose contributed by radon and thoron progeny in environments. In order to measure the size distribution of thoron progeny attached radioactive aerosols, a device was developed using wire screens. The count median diameter (CMD) and the geometric standard deviation (GSD) of attached radioactive aerosols were calculated by collecting ThB and using CR-39 as detector. Field measurement results at Yangjiang City in Guangdong Province show that the CMDs distribute between 30 and 130 nm, and the GSDs are between 1.9 and 3.3. It also shows that the more humid country, the smaller CMDs, and the ventilation has great influence on the size distribution of aerosols. The CMDs of adobe house are smaller than that of the concrete houses. (authors)

  2. Quantum key distribution without alternative measurements

    CERN Document Server

    Cabello, A

    2000-01-01

    Entanglement swapping between Einstein-Podolsky-Rosen (EPR) pairs can be used to generate the same sequence of random bits in two remote places. A quantum key distribution protocol based on this idea is described. The scheme exhibits the following features. (a) It does not require that Alice and Bob choose between alternative measurements, therefore improving the rate of generated bits by transmitted qubit. (b) It allows Alice and Bob to generate a key of arbitrary length using a single quantum system (three EPR pairs), instead of a long sequence of them. (c) Detecting Eve requires the comparison of fewer bits. (d) Entanglement is an essential ingredient. The scheme assumes reliable measurements of the Bell operator. (20 refs).

  3. In situ measurement using FBGs of process-induced strains during curing of thick glass/epoxy laminate plate

    DEFF Research Database (Denmark)

    Nielsen, Michael Wenani; Schmidt, Jacob Wittrup; Hattel, Jesper Henri

    2012-01-01

    For large composite structures, such as wind turbine blades, thick laminates are required to withstand large in-service loads. During the manufacture of thick laminates, one of the challenges met is avoiding process-induced shape distortions and residual stresses. In this paper, embedded fibre...... Bragg grating sensors are used to monitor process-induced strains during vacuum infusion of a thick glass/epoxy laminate. The measured strains are compared with predictions from a cure hardening instantaneous linear elastic (CHILE) thermomechanical numerical model where different mechanical boundary...... conditions are employed. The accuracy of the CHILE model in predicting process-induced internal strains, in what is essentially a viscoelastic boundary value problem, is investigated. A parametric study is furthermore performed to reveal the effect of increasing the laminate thickness. The numerical model...

  4. Odd-order o.d.f. expansion coefficient determination. Case of diffraction strain measurements on cubic materials under macrostress loading

    International Nuclear Information System (INIS)

    Brakman, C.M.

    1985-01-01

    Diffraction intensity pole figures are often used for the determination of orientation distribution function (o.d.f.) expansion coefficients. The intensity can be seen as a convolution of the o.d.f. times unity with respect to one rotation angle (about the direction of measurement). The 'normal' polycrystalline diffraction experiment only yields the even-order o.d.f. coefficients. The experiment itself imposes a centre of inversion even upon non-centrosymmetric crystals. Crystals may exhibit a centre of inversion themselves. The hkl and anti hanti kanti l contributions to the intensity are indistinguishable then owing to the centre of inversion. As a consequence, the odd-order coefficients cannot be determined. The mean value of a general physical property determined by means of diffraction can be taken as a convolution of the o.d.f. times the single-crystal value of the physical property with respect to the rotation angle mentioned before. The dependency of the physical property on the rotation angle leads to more information being extracted from the o.d.f. in the property's mean-value pole figure. Then, all o.d.f. coefficients may be present in the mean value, i.e. the measurement. Consequently, diffraction-line-shift strain pole figures exhibit even- and odd-order o.d.f. coefficients, present or induced centres of inversion notwithstanding. If the dependency of the single-crystal strain on the rotation angle is known no model of elastic polycrystal coupling is needed. However, this does not occur in practice. The present state of the art does not allow the Kroener model to be used for textured materials. In this paper the Reuss model is used. If the (applied) macrostresses are known, the o.d.f. coefficients can be obtained from the formulae presented. (orig.)

  5. Temperature measurement by thermal strain imaging with diagnostic power ultrasound, with potential for thermal index determination.

    Science.gov (United States)

    Liang, Hai-Dong; Zhou, Li-Xia; Wells, Peter N T; Halliwell, Michael

    2009-05-01

    Over the years, there has been a substantial increase in acoustic exposure in diagnostic ultrasound as new imaging modalities with higher intensities and frame rates have been introduced; and more electronic components have been packed into the probe head, so that there is a tendency for it to become hotter. With respect to potential thermal effects, including those which may be hazardous occurring during ultrasound scanning, there is a correspondingly growing need for in vivo techniques to guide the operator as to the actual temperature rise occurring in the examined tissues. Therefore, an in vivo temperature estimator would be of considerable practical value. The commonly-used method of tissue thermal index (TI) measurement with a hydrophone in water could underestimate the actual value of TI (in one report by as much as 2.9 times). To obtain meaningful results, it is necessary to map the temperature elevation in 2-D (or 3-D) space. We present methodology, results and validation of a 2-D spatial and temporal thermal strain ultrasound temperature estimation technique in phantoms, and its apparently novel application in tracking the evolution of heat deposition at diagnostic exposure levels. The same ultrasound probe is used for both transmission and reception. The displacement and thermal strain estimation methods are similar to those used in high-intensity focused ultrasound thermal monitoring. The use of radiofrequency signals permits the application of cross correlation as a similarity measurement for tracking feature displacement. The displacement is used to calculate the thermal strain directly related to the temperature rise. Good agreement was observed between the temperature rise and the ultrasound power and scan duration. Thermal strain up to 1.4% was observed during 4000-s scan. Based on the results obtained for the temperature range studied in this work, the technique demonstrates potential for applicability in phantom (and possibly in vivo tissue

  6. Study of coherence strain of GP II zones in an aged aluminum composite

    International Nuclear Information System (INIS)

    Hernández-Rivera, J.L.; Rivera, J.J. Cruz; Koch, C.T.; Özdöl, V.B.; Martínez-Sánchez, R.

    2012-01-01

    Highlights: ► Precipitation sequence was changed in 2024 Al alloy. ► Image artifacts ought to the mask size and shape increased the real strain value. ► The strain distribution around experimental GP area was non uniform and more complex than reference. ► The origin of this strain distribution are related to mechanisms by which GP precipitates lose coherence. - Abstract: Strain mapping using the geometric phase analysis (GPA) technique was applied to Al–GP II (Guinier–Preston) nanoscale precipitates, using both high resolution transmission electron microscopy (HRTEM) micrographs as well as the exit wave function (EWF) obtained by focal series reconstruction. The experimental strain results were compared with strain maps obtained from an atomic model which consisted of an Al supercell containing a GP II precipitate. It was built as a reference from literature data. The experimental results demonstrate a complex strain distribution and larger fluctuations than the reference strain maps. These differences were found to be partly a consequence of image artifacts produced by the technique as well as complex microstructural events which were present at the development stage studied.

  7. A new setup to measure bidirectional reflectance distribution functions

    NARCIS (Netherlands)

    Roosjen, P.P.J.; Clevers, J.G.P.W.; Bartholomeus, H.

    2012-01-01

    The Plant Facility, a new laboratory goniometer system, built by the Wageningen University has been tested in order to take bidirectional reflectance distribution function (BRDF) measurements. An ASD FieldSpec 3 spectroradiometer mounted on an industrial robot arm is able to measure small targets

  8. measurements of distribution coefficients and lipophilicity values

    African Journals Online (AJOL)

    Preferred Customer

    octanol and water, followed by measuring the distribution of the solute in ... Instrumentation and apparatus: HPLC-UV-DAD and HPLC–ESI-MS experiments .... process in the determination of KD and log P values for the HFSLM extracts. ..... Perrin, D.D.; Dempsey, B. Buffers for pH and Metal Ion Control, Chapman and Hall:.

  9. Variation in the strain anisotropy of Zircaloy with temperature and strain

    International Nuclear Information System (INIS)

    Hindle, E.D.; Worswick, D.

    1984-04-01

    Strain anisotropy was investigated at temperatures in the range 293 to 1117K in circular tensile specimens prepared from rolled Zircaloy-2 plate so that their tensile axes were parallel to and transverse to the rolling direction. The strain anisotropy factor for both types of specimen increased markedly in the high alpha phase region above 923K reaching a maximum at circa 1070K. Above this temperature in the alpha-plus-beta phase region the strain anisotropy decreased rapidly as the proportion of beta phase increased and was almost non-existent at 1173K. The strain anisotropy was markedly strain dependent, particularly in the high alpha phase region. The study was extended to Zircaloy-4 pressurized water reactor (PWR) 17 x 17 type fuel rod tubing specimens which were strained under biaxial conditions using cooling conditions which promoted uniform diametral strain over most of their lengths (circa 250 mm). In these circumstances the strain anisotropy is manifest by a reduction in length. Measurement of this change along with that in diameter and wall thickness produced data from which the strain anisotropy factor was calculated. The results, although influenced by additional factors discussed in the paper, were similar to those observed in the uniaxial Zircaloy-2 tensile tests. (author)

  10. Differential pressure distribution measurement for the development of insect-sized wings

    International Nuclear Information System (INIS)

    Takahashi, Hidetoshi; Matsumoto, Kiyoshi; Shimoyama, Isao

    2013-01-01

    This paper reports on the measurement of the differential pressure distribution over a flat, thin wing using a micro-electro-mechanical systems sensor. Sensors featuring a piezoresistive cantilever were attached to a polyimide/Cu wing. Because the weight of the cantilever element was less than 10 ng, the sensor can measure the differential pressure without interference from inertial forces, such as wing flapping motions. The dimensions of the sensor chips and the wing were 1.0 mm × 1.0 mm × 0.3 mm and 100 mm × 30 mm × 1 mm, respectively. The differential pressure distribution along the wing's chord direction was measured in a wind tunnel at an air velocity of 4.0 m s –1 by changing the angle of attack. It was confirmed that the pressure coefficient calculated by the measured differential pressure distribution was similar to the value measured by a load cell. (paper)

  11. Measurement of neutral beam power and beam profile distribution on DNB

    International Nuclear Information System (INIS)

    Liu Zhimin; Liu Sheng; Song Shihua; Han Xiaopu; Li Jun; Hu Chundong; Hu Liqun; Xie Jun

    2005-01-01

    The injection power of a diagnostic neutral beam (DNB) can be obtained with the thermocouple probe measurement system on the Hefei superconducting Tokamak-7 (HT-7). With the 49 kv, 6 A, 100 ms pulse charge of an acceleration electrode, a thermocouple probe measurement system with 13 thermocouples crossly distributed on a coppery heat target was used to measure the temperature rise of the target, and the maximum measured temperature rise was 14 degree C. And the neutral beam power of 160 kW and beam profile distribution was obtained by calculation. The total neutral beam power of 130 kW was also obtained by integral calculation with the temperature rise on the heat section board. The difference between the two means was analyzed. The experiment results shows that the method of heat section board with thermocouple probe is one of the effective ways to measure the beam power and beam profile distribution. (authors)

  12. Plasmids in Vibrio parahemolyticus strains isolated in Japan and Bangladesh with special reference to different distributions.

    Science.gov (United States)

    Arai, T; Ando, T; Kusakabe, A; Ullah, M A

    1983-01-01

    We surveyed plasmids in naturally occurring Vibrio parahemolyticus strains isolated in Japan and Bangladesh. Among the strains isolated in Japan, about half of the strains isolated from stools of patients of domestic diarrhea outbreaks as well as of travelers returning from East Asia were found to have plasmids, but no strains from foods had plasmids. In contrast, among the strains isolated in Bangladesh, none of the four strains isolated from patients had plasmids, but two out of eight strains isolated from water had plasmids, suggesting that plasmids are common in strains from the water in Bangladesh. All plasmids so far reported in V. parahemolyticus were detected in strains isolated from stools of patients. Incidences of plasmids in this organism were not so high in either area. In Japan, all plasmids were detected in strains from human intestines at 37 C, but in Bangladesh, where the temperature is around 30-40 C, the plasmids were detected in strains from the natural environment. These results suggested the possibility that these plasmids can come from different bacteria under rather high temperatures and that incidences of plasmids are influenced by the incidences of plasmids in bacteria present in the vicinity of V. parahemolyticus strains. None of these plasmids were found to have any relation to the biological characters tested.

  13. Single-size thermometric measurements on a size distribution of neutral fullerenes.

    Science.gov (United States)

    Cauchy, C; Bakker, J M; Huismans, Y; Rouzée, A; Redlich, B; van der Meer, A F G; Bordas, C; Vrakking, M J J; Lépine, F

    2013-05-10

    We present measurements of the velocity distribution of electrons emitted from mass-selected neutral fullerenes, performed at the intracavity free electron laser FELICE. We make use of mass-specific vibrational resonances in the infrared domain to selectively heat up one out of a distribution of several fullerene species. Efficient energy redistribution leads to decay via thermionic emission. Time-resolved electron kinetic energy distributions measured give information on the decay rate of the selected fullerene. This method is generally applicable to all neutral species that exhibit thermionic emission and provides a unique tool to study the stability of mass-selected neutral clusters and molecules that are only available as part of a size distribution.

  14. Composite Cure Process Modeling and Simulations using COMPRO(Registered Trademark) and Validation of Residual Strains using Fiber Optics Sensors

    Science.gov (United States)

    Sreekantamurthy, Thammaiah; Hudson, Tyler B.; Hou, Tan-Hung; Grimsley, Brian W.

    2016-01-01

    Composite cure process induced residual strains and warping deformations in composite components present significant challenges in the manufacturing of advanced composite structure. As a part of the Manufacturing Process and Simulation initiative of the NASA Advanced Composite Project (ACP), research is being conducted on the composite cure process by developing an understanding of the fundamental mechanisms by which the process induced factors influence the residual responses. In this regard, analytical studies have been conducted on the cure process modeling of composite structural parts with varied physical, thermal, and resin flow process characteristics. The cure process simulation results were analyzed to interpret the cure response predictions based on the underlying physics incorporated into the modeling tool. In the cure-kinetic analysis, the model predictions on the degree of cure, resin viscosity and modulus were interpreted with reference to the temperature distribution in the composite panel part and tool setup during autoclave or hot-press curing cycles. In the fiber-bed compaction simulation, the pore pressure and resin flow velocity in the porous media models, and the compaction strain responses under applied pressure were studied to interpret the fiber volume fraction distribution predictions. In the structural simulation, the effect of temperature on the resin and ply modulus, and thermal coefficient changes during curing on predicted mechanical strains and chemical cure shrinkage strains were studied to understand the residual strains and stress response predictions. In addition to computational analysis, experimental studies were conducted to measure strains during the curing of laminated panels by means of optical fiber Bragg grating sensors (FBGs) embedded in the resin impregnated panels. The residual strain measurements from laboratory tests were then compared with the analytical model predictions. The paper describes the cure process

  15. Trends in natural gas distribution and measurements

    International Nuclear Information System (INIS)

    Crone, C.F.A.

    1993-01-01

    On the occasion of the GAS EXPO 93, to be held from 13-15 October 1993 in Amsterdam, Netherlands, an overview is given of trends in the distribution of natural gas and the measuring of natural gas, as noted by experts from the energy utilities, GASTEC and Gasunie in the Netherlands. With regard to the natural gas distribution trends attention is paid to synthetic materials, the environmental effects, maintenance, underground natural gas pressure control, horizontal drilling (no-dig techniques), and other trends. With regard to natural gas metering trends brief discussions are given of the direct energy meter, the search for a new gas meter in households, telemetering, improving the accuracy of the gas meters by means of electronics, on the spot calibration of large gas meters, the use of an online chromatograph to determine the calorific value, the development of a calibration instrument, the so-called piston prover, to measure large quantities of natural gas, the recalibration of natural gas stations, the ultrasonic gas meter, and finally the quality of the natural gas supply. 1 fig., 11 ills

  16. Metallic-packaging fiber Bragg grating sensor based on ultrasonic welding for strain-insensitive temperature measurement

    Science.gov (United States)

    Zhu, Lianqing; Yang, Runtao; Zhang, Yumin; Dong, Mingli; Lou, Xiaoping

    2018-04-01

    In this paper, a metallic-packaging fiber Bragg grating temperature sensor characterized by a strain insensitive design is demonstrated. The sensor is fabricated by the one-step ultrasonic welding technique using type-II fiber Bragg grating combined with an aluminum alloy substrate. Finite element analysis is used to perform theoretical evaluation. The result of the experiment illustrates that the metallic-packaging temperature sensor is insensitive to longitudinal strain. The sensor's temperature sensitivity is 36 pm/°C over the range of 50-110 °C, with the correlation coefficient (R2) being 0.999. The sensor's temporal response is 40 s at a sudden temperature change from 21 °C to 100 °C. The proposed sensor can be applied on reliable and precise temperature measurement.

  17. Processing of plane strain compression test results for investigation of AISI-304 stainless steel constitutive behavior

    International Nuclear Information System (INIS)

    Aksenov, Sergey A.; Puzino, Yuriy A.; Bober, Stanislav A.; Kliber, Jiri

    2015-01-01

    The paper is oriented toward the determination of constitutive equation constants by the inverse analysis of plane strain compression test results. The interpretation of such results is complicated by the inhomogeneity of strain rate distribution in the specimen caused by rigid ends, the lateral spreading of a specimen friction and the variation of temperature during the test. The results of plane strain compression tests of AISI-304 stainless steel are presented and significant deviations of temperature are observed at higher strain rates. Finite element simulation was performed to estimate the inhomogeneity of strain rate within the specimen and evaluate the effect of friction on the test results. Constitutive equations of the material were obtained by inverse analysis minimizing the deviations between the measured load values and the ones predicted by numerical simulation. Keywords: PSCT, AISI-304, Gleeble, constitutive equations, hot forming, FEM, inverse analysis.

  18. Coupon Test of an Elbow Component by Using Vision-based Measurement System

    International Nuclear Information System (INIS)

    Kim, Sung Wan; Jeon, Bub Gyu; Choi, Hyoung Suk; Kim, Nam Sik

    2016-01-01

    Among the various methods to overcome this shortcoming, vision-based methods to measure the strain of a structure are being proposed and many studies are being conducted on them. The vision-based measurement method is a noncontact method for measuring displacement and strain of objects by comparing between images before and after deformation. This method offers such advantages as no limitations in the surface condition, temperature, and shape of objects, the possibility of full filed measurement, and the possibility of measuring the distribution of stress or defects of structures based on the measurement results of displacement and strain in a map. The strains were measured with various methods using images in coupon test and the measurements were compared. In the future, the validity of the algorithm will be compared using stain gauge and clip gage, and based on the results, the physical properties of materials will be measured using a vision-based measurement system. This will contribute to the evaluation of reliability and effectiveness which are required for investigating local damages

  19. Coupon Test of an Elbow Component by Using Vision-based Measurement System

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Wan; Jeon, Bub Gyu; Choi, Hyoung Suk; Kim, Nam Sik [Pusan National University, Busan (Korea, Republic of)

    2016-05-15

    Among the various methods to overcome this shortcoming, vision-based methods to measure the strain of a structure are being proposed and many studies are being conducted on them. The vision-based measurement method is a noncontact method for measuring displacement and strain of objects by comparing between images before and after deformation. This method offers such advantages as no limitations in the surface condition, temperature, and shape of objects, the possibility of full filed measurement, and the possibility of measuring the distribution of stress or defects of structures based on the measurement results of displacement and strain in a map. The strains were measured with various methods using images in coupon test and the measurements were compared. In the future, the validity of the algorithm will be compared using stain gauge and clip gage, and based on the results, the physical properties of materials will be measured using a vision-based measurement system. This will contribute to the evaluation of reliability and effectiveness which are required for investigating local damages.

  20. Investigation of a Cross-Correlation Based Optical Strain Measurement Technique for Detecting radial Growth on a Rotating Disk

    Science.gov (United States)

    Clem, Michelle M.; Woike, Mark R.

    2013-01-01

    The Aeronautical Sciences Project under NASA`s Fundamental Aeronautics Program is extremely interested in the development of novel measurement technologies, such as optical surface measurements in the internal parts of a flow path, for in situ health monitoring of gas turbine engines. In situ health monitoring has the potential to detect flaws, i.e. cracks in key components, such as engine turbine disks, before the flaws lead to catastrophic failure. In the present study, a cross-correlation imaging technique is investigated in a proof-of-concept study as a possible optical technique to measure the radial growth and strain field on an already cracked sub-scale turbine engine disk under loaded conditions in the NASA Glenn Research Center`s High Precision Rotordynamics Laboratory. The optical strain measurement technique under investigation offers potential fault detection using an applied high-contrast random speckle pattern and imaging the pattern under unloaded and loaded conditions with a CCD camera. Spinning the cracked disk at high speeds induces an external load, resulting in a radial growth of the disk of approximately 50.0-im in the flawed region and hence, a localized strain field. When imaging the cracked disk under static conditions, the disk will be undistorted; however, during rotation the cracked region will grow radially, thus causing the applied particle pattern to be .shifted`. The resulting particle displacements between the two images will then be measured using the two-dimensional cross-correlation algorithms implemented in standard Particle Image Velocimetry (PIV) software to track the disk growth, which facilitates calculation of the localized strain field. In order to develop and validate this optical strain measurement technique an initial proof-of-concept experiment is carried out in a controlled environment. Using PIV optimization principles and guidelines, three potential speckle patterns, for future use on the rotating disk, are developed

  1. Global carbon monoxide vertical distributions from spaceborne high-resolution FTIR nadir measurements

    Directory of Open Access Journals (Sweden)

    B. Barret

    2005-01-01

    Full Text Available This paper presents the first global distributions of CO vertical profiles retrieved from a thermal infrared FTS working in the nadir geometry. It is based on the exploitation of the high resolution and high quality spectra measured by the Interferometric Monitor of Greenhouse gases (IMG which flew onboard the Japanese ADEOS platform in 1996-1997. The retrievals are performed with an algorithm based on the Optimal Estimation Method (OEM and are characterized in terms of vertical sensitivity and error budget. It is found that most of the IMG measurements contain between 1.5 and 2.2 independent pieces of information about the vertical distribution of CO from the lower troposphere to the upper troposphere-lower stratosphere (UTLS. The retrievals are validated against coincident NOAA/CMDL in situ surface measurements and NDSC/FTIR total columns measurements. The retrieved global distributions of CO are also found to be in good agreement with the distributions modeled by the GEOS-CHEM 3D CTM, highlighting the ability of IMG to capture the horizontal as well as the vertical structure of the CO distributions.

  2. Measurement based scenario analysis of short-range distribution system planning

    DEFF Research Database (Denmark)

    Chen, Peiyuan; Bak-Jensen, Birgitte; Chen, Zhe

    2009-01-01

    This paper focuses on short-range distribution system planning using a probabilistic approach. Empirical probabilistic distributions of load demand and distributed generations are derived from the historical measurement data and incorporated into the system planning. Simulations with various...... feasible scenarios are performed based on a local distribution system at Støvring in Denmark. Simulation results provide more accurate and insightful information for the decision-maker when using the probabilistic analysis than using the worst-case analysis, so that a better planning can be achieved....

  3. Blood pressure measurement of all five fingers by strain gauge plethysmography

    DEFF Research Database (Denmark)

    Hirai, M; Nielsen, S L; Lassen, N A

    1976-01-01

    of the other fingers was measured using a 24-mm-wide cuff. Blood pressure at the proximal phalanx was higher than that at the intermediate phalanx in all fingers except finger V. The difference of blood pressure values corresponded well with circumference of the finger. In 15 normal subjects, blood pressure...... at the proximal phalanx was compared in fingers I, III, IV, and V, using 16, 20, 24 and 24 mm wide cuffs. Finger blood pressure was closest to arm systolic blood pressure when a 24-mm or 27-mm-wide cuff was used in fingers I, III, and IV, and with a 20-mm-wide cuff in finger V. As the standard deviation......The aim of the present paper was to study the methodological problems involved in measuring systolic blood pressure in all five fingers by the strain gauge technique. In 24 normal subjects, blood pressure at the proximal phalanx of finger I and both at the proximal and the intermediate phalanx...

  4. Assessing the small-strain soil stiffness for offshore wind turbines based on in situ seismic measurements

    NARCIS (Netherlands)

    Versteijlen, W.G.; Van Dalen, K.N.; Metrikine, A.; Hamre, L.

    2014-01-01

    In this contribution, in situ seismic measurements are used to derive the small-strain shear modulus of soil as input for two soil-structure interaction (SSI) models to assess the initial soil stiffness for offshore wind turbine foundations. This stiffness has a defining influence on the first

  5. Dynamic fiber Bragg grating strain sensor interrogation with real-time measurement

    Science.gov (United States)

    Park, Jinwoo; Kwon, Yong Seok; Ko, Myeong Ock; Jeon, Min Yong

    2017-11-01

    We demonstrate a 1550 nm band resonance Fourier-domain mode-locked (FDML) fiber laser with fiber Bragg grating (FBG) array. Using the FDML fiber laser, we successfully demonstrate real-time monitoring of dynamic FBG strain sensor interrogation for structural health monitoring. The resonance FDML fiber laser consists of six multiplexed FBGs, which are arranged in series with delay fiber lengths. It is operated by driving the fiber Fabry-Perot tunable filter (FFP-TF) with a sinusoidal waveform at a frequency corresponding to the round-trip time of the laser cavity. Each FBG forms a laser cavity independently in the FDML fiber laser because the light travels different length for each FBG. The very closely positioned two FBGs in a pair are operated simultaneously with a frequency in the FDML fiber laser. The spatial positions of the sensing pair can be distinguished from the variation of the applied frequency to the FFP-TF. One of the FBGs in the pair is used as a reference signal and the other one is fixed on the piezoelectric transducer stack to apply the dynamic strain. We successfully achieve real-time measurement of the abrupt change of the frequencies applied to the FBG without any signal processing delay. The real-time monitoring system is displayed simultaneously on the monitor for the variation of the two peaks, the modulation interval of the two peaks, and their fast Fourier transform spectrum. The frequency resolution of the dynamic variation could reach up to 0.5 Hz for 2 s integration time. It depends on the integration time to measure the dynamic variation. We believe that the real-time monitoring system will have a potential application for structural health monitoring.

  6. Residual-stress measurements

    Energy Technology Data Exchange (ETDEWEB)

    Ezeilo, A N; Webster, G A [Imperial College, London (United Kingdom); Webster, P J [Salford Univ. (United Kingdom)

    1997-04-01

    Because neutrons can penetrate distances of up to 50 mm in most engineering materials, this makes them unique for establishing residual-stress distributions non-destructively. D1A is particularly suited for through-surface measurements as it does not suffer from instrumental surface aberrations commonly found on multidetector instruments, while D20 is best for fast internal-strain scanning. Two examples for residual-stress measurements in a shot-peened material, and in a weld are presented to demonstrate the attractive features of both instruments. (author).

  7. Characterization of strained semiconductor structures using transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Oezdoel, Vasfi Burak

    2011-08-15

    Today's state-of-the-art semiconductor electronic devices utilize the charge transport within very small volumes of the active device regions. The structural, chemical and optical material properties in these small dimensions can critically affect the performance of these devices. The present thesis is focused on the nanometer scale characterization of the strain state in semiconductor structures using transmission electron microscopy (TEM). Although high-resolution TEM has shown to provide the required accuracy at the nanometer scale, optimization of imaging conditions is necessary for accurate strain measurements. An alternative HRTEM method based on strain mapping on complex-valued exit face wave functions is developed to reduce the artifacts arising from objective lens aberrations. However, a much larger field of view is crucial for mapping strain in the active regions of complex structures like latest generation metal-oxide-semiconductor field-effect transistors (MOSFETs). To overcome this, a complementary approach based on electron holography is proposed. The technique relies on the reconstruction of the phase shifts in the diffracted electron beams from a focal series of dark-field images using recently developed exit-face wave function reconstruction algorithm. Combining high spatial resolution, better than 1 nm, with a field of view of about 1 {mu}m in each dimension, simultaneous strain measurements on the array of MOSFETs are possible. Owing to the much lower electron doses used in holography experiments when compared to conventional quantitative methods, the proposed approach allows to map compositional distribution in electron beam sensitive materials such as InGaN heterostructures without alteration of the original morphology and chemical composition. Moreover, dark-field holography experiments can be performed on thicker specimens than the ones required for high-resolution TEM, which in turn reduces the thin foil relaxation. (orig.)

  8. Device for measuring neutron-flux distribution density

    International Nuclear Information System (INIS)

    Rozenbljum, N.D.; Mitelman, M.G.; Kononovich, A.A.; Kirsanov, V.S.; Zagadkin, V.A.

    1977-01-01

    An arrangement is described for measuring the distribution of neutron flux density over the height of a nuclear reactor core and which may be used for monitoring energy release or for detecting deviations of neutron flux from an optimal level so that subsequent balance can be achieved. It avoids mutual interference of detectors. Full constructional details are given. (UK)

  9. Distribution, detection of enterotoxigenic strains and antimicrobial drug susceptibility patterns of Bacteroides fragilis group in diarrheic and non-diarrheic feces from Brazilian infants

    Directory of Open Access Journals (Sweden)

    Débora Paula Ferreira

    2010-10-01

    Full Text Available Despite the importance of gastrointestinal diseases and their global distribution, affecting millions of individuals around the world, the role and antimicrobial susceptibility patterns of anaerobic bacteria such as those in the Bacteroides fragilis group (BFG are still unclear in young children. This study investigated the occurrence and distribution of species in the BFG and enterotoxigenic strains in the fecal microbiota of children and their antimicrobial susceptibility patterns. Diarrheic (n=110 and non-diarrheic (n=65 fecal samples from children aged 0-5 years old were evaluated. BFG strains were isolated and identified by conventional biochemical, physiological and molecular approaches. Alternatively, bacteria and enterotoxigenic strains were detected directly from feces by molecular biology. Antimicrobial drug susceptibility patterns were determined by the agar dilution method according to the guidelines for isolated bacteria. BFG was detected in 64.3% of the fecal samples (55% diarrheic and 80.4% non-diarrheic, and 4.6% were enterotoxigenic. Antimicrobial resistance was observed against ampicillin, ampicillin/sulbactam, piperacillin/tazobactam, meropenem, ceftriaxone, clindamycin and chloramphenicol. The data show that these bacteria are prevalent in fecal microbiota at higher levels in healthy children. The molecular methodology was more effective in identifying the B. fragilis group when compared to the biochemical and physiological techniques. The observation of high resistance levels stimulates thoughts about the indiscriminate use of antimicrobial drugs in early infancy. Further quantitative studies are needed to gain a better understanding of the role of these bacteria in acute diarrhea in children.

  10. An Embeddable Strain Sensor with 30 Nano-Strain Resolution Based on Optical Interferometry

    Directory of Open Access Journals (Sweden)

    Chen Zhu

    2018-04-01

    Full Text Available A cost-effective, robust and embeddable optical interferometric strain sensor with nanoscale strain resolution is presented in this paper. The sensor consists of an optical fiber, a quartz rod with one end coated with a thin gold layer, and two metal shells employed to transfer the strain and orient and protect the optical fiber and the quartz rod. The optical fiber endface, combining with the gold-coated surface, forms an extrinsic Fabry–Perot interferometer. The sensor was firstly calibrated, and the result showed that our prototype sensor could provide a measurement resolution of 30 nano-strain (nε and a sensitivity of 10.01 µε/µm over a range of 1000 µε. After calibration of the sensor, the shrinkage strain of a cubic brick of mortar in real time during the drying process was monitored. The strain sensor was compared with a commercial linear variable displacement transducer, and the comparison results in four weeks demonstrated that our sensor had much higher measurement resolution and gained more detailed and useful information. Due to the advantages of the extremely simple, robust and cost-effective configuration, it is believed that the sensor is significantly beneficial to practical applications, especially for structural health monitoring.

  11. Simultaneous measurement of strain, temperature and refractive index based on multimode interference, fiber tapering and fiber Bragg gratings

    International Nuclear Information System (INIS)

    Oliveira, Ricardo; Osório, Jonas H; Aristilde, Stenio; Cordeiro, Cristiano M B; Bilro, Lúcia; Nogueira, Rogerio N

    2016-01-01

    We report the development of an optical fiber sensor capable of simultaneously measuring strain, temperature and refractive index. The sensor is based on the combination of two fiber Bragg gratings written in a standard single-mode fiber, one in an untapered region and another in a tapered region, spliced to a no-core fiber. The possibility of simultaneously measuring three parameters relies on the different sensitivity responses of each part of the sensor. The results have shown the possibility of measuring three parameters simultaneously with a resolution of 3.77 με , 1.36 °C and 5  ×  10 −4 , respectively for strain, temperature and refractive index. On top of the multiparameter ability, the simple production and combination of all the parts involved on this optical-fiber-based sensor is an attractive feature for several sensing applications. (paper)

  12. Unstable Temperature Distribution in Friction Stir Welding

    Directory of Open Access Journals (Sweden)

    Sadiq Aziz Hussein

    2014-01-01

    Full Text Available In the friction stir welding process, a nonuniform and high generated temperature is undesirable. Unstable temperature and distribution affect thermal and residual stresses along the welding line, thus necessitating mitigation. This paper presents a simple method to prevent significant temperature difference along the welding line and also to help nullifying some defect types associated with this welding, such as end-hole, initial unwelded line, and deformed areas. In the experimental investigation, a heat and force thermocouple and dynamometer were utilized while couple-field thermomechanical models were used to evaluate temperature and its distribution, plastic strain, and material displacement. The suggested method generated uniform temperature distributions. Measurement results are discussed, showing a good correlation with predictions.

  13. About the inevitable compromise between spatial resolution and accuracy of strain measurement for bone tissue: a 3D zero-strain study.

    Science.gov (United States)

    Dall'Ara, E; Barber, D; Viceconti, M

    2014-09-22

    The accurate measurement of local strain is necessary to study bone mechanics and to validate micro computed tomography (µCT) based finite element (FE) models at the tissue scale. Digital volume correlation (DVC) has been used to provide a volumetric estimation of local strain in trabecular bone sample with a reasonable accuracy. However, nothing has been reported so far for µCT based analysis of cortical bone. The goal of this study was to evaluate accuracy and precision of a deformable registration method for prediction of local zero-strains in bovine cortical and trabecular bone samples. The accuracy and precision were analyzed by comparing scans virtually displaced, repeated scans without any repositioning of the sample in the scanner and repeated scans with repositioning of the samples. The analysis showed that both precision and accuracy errors decrease with increasing the size of the region analyzed, by following power laws. The main source of error was found to be the intrinsic noise of the images compared to the others investigated. The results, once extrapolated for larger regions of interest that are typically used in the literature, were in most cases better than the ones previously reported. For a nodal spacing equal to 50 voxels (498 µm), the accuracy and precision ranges were 425-692 µε and 202-394 µε, respectively. In conclusion, it was shown that the proposed method can be used to study the local deformation of cortical and trabecular bone loaded beyond yield, if a sufficiently high nodal spacing is used. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Statistical analysis of the distribution of critical current and the correlation of n value to the critical current of bent Bi2223 composite tape

    International Nuclear Information System (INIS)

    Ochiai, S; Matsubayashi, H; Okuda, H; Osamura, K; Otto, A; Malozemoff, A

    2009-01-01

    Distributions of local and overall critical currents and correlation of n value to the critical current of bent Bi2223 composite tape were studied from the statistical viewpoint. The data of the local and overall transport critical currents and n values of the Bi2223 composite tape specimens were collected experimentally for a wide range of bending strain (0-1.1%) by using the specimens, designed so as to characterize the local and overall critical currents and n values. The measured local and overall critical currents were analyzed with various types of Weibull distribution function. Which of the Weibull distribution functions is suitable for the description of the distribution of local and overall critical currents at each bending strain, and also how much the Weibull parameter values characterizing the distribution vary with bending strain, were revealed. Then we attempted to reproduce the overall critical current distribution and correlation of the overall n value to the overall critical current from the distribution of local critical currents and the correlation of the local n value to the local critical current by a Monte Carlo simulation. The measured average values of critical current and n value at each bending strain and the correlation of n value to critical current were reproduced well by the present simulation, while the distribution of critical current values was reproduced fairly well but not fully. The reason for this is discussed.

  15. Measurement of power distribution in FCA-HCLWR core (Phase-1)

    International Nuclear Information System (INIS)

    Ohno, Akio; Osugi, Toshitaka; Satoh, Kunio

    1991-11-01

    In the report are described experiments with zone-type mock-up cores (FCA XIV) which consisted of uranium fuels and polystilene plates, assembled at FCA (Fast Critical Assembly), to study a series of physical characteristics for high conversion light water reactors. As one example of those characteristics, power distributions were measured by a γ-counting method in the mock-up cores by changing parametrically voidage states of the moderator, volume ratio of moderator to fuel and fuel enrichment. Fine structures of fission rate in a plate-array cell having strong heterogeneities were obtained at the center cell of the core to investigate the validity of the SRAC code for the analysis of the high conversion light water reactor. Furthermore infinite multiplication factors K ∞ which are an important physical parameter were derived from calculated migration areas and bucklings of each direction. This was obtained by fitting the measured power distributions into a cosine function. Calculated power distributions of radial directions overestimate largely the measure ones, while those of axial directions agree well with the measured values. Calculations on fine structure of fission ratio in the cell follow generally the measured values, but it is recognized that the calculation underestimates the measurement in a soft neutron spectrum core. As for infinite multiplication factors K ∞ , calculated values by the SRAC code agree within experimental errors with measured ones. No trend is observed on different voidage state of moderator and fuel enrichment in the limit of this experiment. (author)

  16. Influence of the statistical distribution of bioassay measurement errors on the intake estimation

    International Nuclear Information System (INIS)

    Lee, T. Y; Kim, J. K

    2006-01-01

    The purpose of this study is to provide the guidance necessary for making a selection of error distributions by analyzing influence of statistical distribution for a type of bioassay measurement error on the intake estimation. For this purpose, intakes were estimated using maximum likelihood method for cases that error distributions are normal and lognormal, and comparisons between two distributions for the estimated intakes were made. According to the results of this study, in case that measurement results for lung retention are somewhat greater than the limit of detection it appeared that distribution types have negligible influence on the results. Whereas in case of measurement results for the daily excretion rate, the results obtained from assumption of a lognormal distribution were 10% higher than those obtained from assumption of a normal distribution. In view of these facts, in case where uncertainty component is governed by counting statistics it is considered that distribution type have no influence on intake estimation. Whereas in case where the others are predominant, it is concluded that it is clearly desirable to estimate the intake assuming a lognormal distribution

  17. Measuring Geographic Distribution of Economic Activity in Nigeria ...

    African Journals Online (AJOL)

    Measuring Geographic Distribution of Economic Activity in Nigeria Using Gross Domestic Product. ... and environmental factors in planning. There is need for adequate understanding of spatial pattern and centrographic analysis of economic activity to support evidence based economic and regional development policies.

  18. Development of a relationship between external measurements and reinforcement stress

    Science.gov (United States)

    Brault, Andre; Hoult, Neil A.; Lees, Janet M.

    2015-03-01

    As many countries around the world face an aging infrastructure crisis, there is an increasing need to develop more accurate monitoring and assessment techniques for reinforced concrete structures. One of the challenges associated with assessing existing infrastructure is correlating externally measured parameters such as crack widths and surface strains with reinforcement stresses as this is dependent on a number of variables. The current research investigates how the use of distributed fiber optic sensors to measure reinforcement strain can be correlated with digital image correlation measurements of crack widths to relate external crack width measurements to reinforcement stresses. An initial set of experiments was undertaken involving a series of small-scale beam specimens tested in three-point bending with variable reinforcement properties. Relationships between crack widths and internal reinforcement strains were observed including that both the diameter and number of bars affected the measured maximum strain and crack width. A model that uses measured crack width to estimate reinforcement strain was presented and compared to the experimental results. The model was found to provide accurate estimates of load carrying capacity for a given crack width, however, the model was potentially less accurate when crack widths were used to estimate the experimental reinforcement strains. The need for more experimental data to validate the conclusions of this research was also highlighted.

  19. Measurements of the angular distribution of diffuse irradiance

    DEFF Research Database (Denmark)

    Andersen, Elsa; Nielsen, Kristian Pagh; Dragsted, Janne

    2015-01-01

    Advanced solar resource assessment and forecasting is necessary for optimal solar energy utilization. In order to investigate the short-term resource variability, for instance caused by clouds it is necessary to investigate how clouds affect the solar irradiance, including the angular distribution...... of the solar irradiance. The investigation is part of the Danish contribution to the taskforce 46 within the International Energy Agency and financed by the Danish Energy Agency. The investigation focuses on the distribution of the diffuse solar irradiance and is based on horizontal measurements of the solar...

  20. Quantitative strain analysis for advanced CMOS technology by Nano Beam Diffraction

    KAUST Repository

    Wang, Qingxiao

    2010-07-01

    Nano Beam Diffraction has been used to analyze the local strain distribution in MOS transistors. The influence of wafer process on the channel strain has been systematically analyzed in this paper. The source/drain implantation can cause a little strain loss but the silicidation step is the key process in which dramatic strain loss has been found. © 2010 IEEE.