Journal articles: 'Surface strain measurement'

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Butcher, Emily, Andrew Gibson, Philip M. Benson, Nick Koor, and Gareth Swift. "Near infrared spectroscopic measurement of strain in rocks." Journal of Near Infrared Spectroscopy 27, no. 6 (August 28, 2019): 432–40. http://dx.doi.org/10.1177/0967033519872540.

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The measurement of strain is a fundamental and widely studied parameter in engineering, rock mechanics, construction and materials testing. Contact sensors often used in these fields require contact with the target surface throughout the duration of a strain event. Non-contact methods typically require that that the measurement surface is prepared and often coated prior to testing. This paper considers the potential application of near infrared spectroscopy as a non-contact technique for the measurement of strain on natural surfaces. Excellent correlation was found between surface measurements of visible-NIR spectra and longitudinal strain taken during indirect Brazilian Disc Test for samples of sandstone, marble and basalt.

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Carabello, Alina, Constanze Neupetsch, Michael Werner, Christian Rotsch, Welf-Guntram Drossel, and Dirk Zajonz. "Comparison of Resistive and Optical Strain Measurement for Early Fracture Detection." Current Directions in Biomedical Engineering 6, no. 3 (September 1, 2020): 196–99. http://dx.doi.org/10.1515/cdbme-2020-3050.

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AbstractTo increase learning success in surgical training, physical simulators are supplemented by measurement technology to generate and record objective feedback and error detection. An opportunity to detect fractures following hip stem implantation early can be measurement of occurring strains on bone surface. These strains can be determined while using strain gauges, digital image correlation (DIC) or photoelasticity. In this research strain gauges and DIC were compared regarding their suitability as strain measurement tools for use in physical simulators. Therefore a testing method was described to replicate the implantation of a hip stem. Testing devices modelled on a realistic prosthesis were pressed into prepared porcine femora in a two-step procedure with a material testing machine. The local strains occurring on bone surface were determined using an optical measurement system for DIC and strain gauges. The initial fractures in the tested femora are located medial-anterior in most cases (73,6%). With increasing indentation depth of the test device, the strains on bone surface increase. Comparing the local strains determined by DIC and strain gauges consistencies in curves are noticeable. Maximal determined strains before fracturing amount to 0,69% with strain gauges and 0,75% with DIC. In the range of the fracture gap, strain gradients are determined by using DIC. However the detected surfaces are of low quality caused by gaps and motion artefacts. The results show strains on bone surfaces for early fracture detection are measurable with strain gauges and DIC. DIC is assessed as less suitable compared to strain gauges. Furthermore strain gauges have greater level of integration and economic efficiency, so they are preferred the use in surgical training simulators.

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Spooner, S., and X. L. Wang. "Diffraction Peak Displacement in Residual Stress Samples Due to Partial Burial of the Sampling Volume." Journal of Applied Crystallography 30, no. 4 (August 1, 1997): 449–55. http://dx.doi.org/10.1107/s0021889897000174.

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Near-surface measurement of residual strain and stress with neutron scattering complements and extends the surface residual stress measurements by X-ray diffraction. However, neutron diffraction measurements near surfaces are sensitive to scattering volume alignment, neutron beam wavelength spread and beam collimation and, unless properly understood, can give large fictitious strains. An analytic calculation and a numerical computation of neutron diffraction peak shifts due to partial burial of the sampling volume have been made and are compared with experimental measurement. Peak shifts in a strain-free nickel sample were determined for conditions where the sample surface is displaced so that the scattering gage volume is partially buried in the sample. The analytic and numerically computed peak shifts take into account the beam collimation, neutron source size, monochromator crystal mosaic spread and the collection of diffracted intensity with a linear position-sensitive counter.

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Schwarzkopf, Matthew, and Lech Muszynski. "Strain distribution and load transfer in the polymer-wood particle bond in wood plastic composites." Holzforschung 69, no. 1 (January 1, 2015): 53–60. http://dx.doi.org/10.1515/hf-2013-0243.

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Abstract The load transfer between wood particles and the matrix was analyzed by observation of the strain patterns in thin films of high density polyethylene (HDPE) with embedded wood particles subjected to tensile loading. Optical measurement techniques based on the digital image correlation (DIC) principle were employed for quantitative measurement of strain distributions on the surfaces of the specimens. Interpretation of these measurements in terms of load transfer between the particle and the matrix below the surface proved challenging and required a structured approach. In this paper, quantitative descriptors were selected as synthesized metrics to support the quantitative interpretation of the measured strains. X-ray computed tomography (XCT) scans were used to assess the effect of the position of the particles in the film specimens on the strains patterns observed on the surface.

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Falk, Alexandru, Octavian Pop, Jérôme Dopeux, and Liviu Marsavina. "Assessment of Strains Produced by Thermal Expansion in Printed Circuit Boards." Materials 15, no. 11 (May 31, 2022): 3916. http://dx.doi.org/10.3390/ma15113916.

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The paper proposed an alternative optical metrology to classical methods (strain gauge measurements and numerical simulation) for strain determination on printed circuit board (PCBs) due to thermal loads. The digital image correlation (DIC) technique was employed to record the strain distribution in some particular areas of the PCB. A thermal load was applied using a heating chamber, and the measurements were performed at four different temperature steps (25 °C, 50 °C, 85 °C and 120 °C). An increase in the principal strains with temperature was observed. For validation, the principal strains on the PCB obtained with DIC were compared with the values from gauge strain measurements and numerical simulation. The conclusions highlighted that DIC represents a technique with potential for strain measurement caused by thermal deformation, with the advantages of full field measurement, less preparation of the surface and good accuracy.

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Umemoto, S., S. Tanoue, N. Miyamoto, T. Takaki, I. Ishii, T. Aoyama, and K. Fujii. "Concrete surface strain measurement using Moiré fringes." Construction and Building Materials 67 (September 2014): 115–20. http://dx.doi.org/10.1016/j.conbuildmat.2013.12.035.

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Best, T. M., J. H. McElhaney, W. E. Garrett, and B. S. Myers. "Axial Strain Measurements in Skeletal Muscle at Various Strain Rates." Journal of Biomechanical Engineering 117, no. 3 (August 1, 1995): 262–65. http://dx.doi.org/10.1115/1.2794179.

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A noncontact optical system using high speed image analysis to measure local tissue deformations and axial strains along skeletal muscle is described. The spatial resolution of the system was 20 pixels/cm and the accuracy was ±0.125mm. In order to minimize the error associated with discrete data used to characterize a continuous strain field, the displacement data were fitted with a third order polynomial and the fitted data differentiated to measure surface strains using a Lagrangian finite strain formulation. The distribution of axial strain along the muscle-tendon unit was nonuniform and rate dependent. Despite a variation in local strain distribution with strain rate, the maximum axial strain, Exx = 0.614 ± 0.045 mm/mm, was rate insensitive and occurred at the failure site for all tests. The frequency response of the video system (1000 Hz) and the measurement of a continuous strain field along the entire length of the structure improve upon previous noncontact optical systems for measurement of surface strains in soft tissues.

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Rajani, B., and C. Zhan. "Indirect estimates of flexural strain in concrete sidewalks induced by vertical movement." Canadian Journal of Civil Engineering 26, no. 3 (June 1, 1999): 312–23. http://dx.doi.org/10.1139/l98-072.

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This paper examines different numerical methods to estimate flexural strain from surface elevation measurements on concrete sidewalks. Surface elevations, along a typical concrete sidewalk cross section, were monitored on a monthly basis as part of a study to determine the cracking mechanism of concrete sidewalks. These measurements were carried out in Calgary, Edmonton, and Camrose, Alberta, between 1993 and mid-1995. Finite difference, cubic spline, polynomial fit, and Fourier series methods of analyses are described for an indirect estimation of flexural strains in sidewalks. The sensitivity of these methods to measurement error is discussed. The Fourier series method is found to be the best procedure to analyse sidewalk surface elevation data for flexural strains estimates. The numerical methods to indirectly determine strain are best suited for those circumstances where installation of strain gauges is difficult, expensive, or impossible.Key words: concrete sidewalks, indirect estimates of flexural strain.

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Grant, B. M. B., H. J. Stone, P. J. Withers, and M. Preuss. "High-temperature strain field measurement using digital image correlation." Journal of Strain Analysis for Engineering Design 44, no. 4 (May 1, 2009): 263–71. http://dx.doi.org/10.1243/03093247jsa478.

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A method is presented for obtaining good images of sample surfaces at high temperatures, suitable for strain measurement, by digital image correlation (DIC) without the use of surface markers or speckles. This is accomplished by suppressing black-body radiation through the use of filters and blue illumination. Using only relatively low levels of illumination the method is demonstrated to be capable of providing accurate DIC measurements up to 1100 °C, and the potential to monitor strains to 1400 °C is identified. The capability of the method is demonstrated by measuring the Young's modulus and coefficient of thermal expansion of a nickel-base superalloy at temperatures from ambient to 1000 °C; two parameters that are well established in the literature and that require high strain sensitivity for their reliable determination.

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KAMAYA, Masayuki, and Masahiro KAWAKUBO. "C101 Growth monitoring of internal surface crack by strain measurement of external surface : Application of multiple strain measurement method." Proceedings of the National Symposium on Power and Energy Systems 2011.16 (2011): 17–20. http://dx.doi.org/10.1299/jsmepes.2011.16.17.

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Grossman, Barry G., Li-Tien Huang, Paul J. Cosentino, and Wulf von Eckroth. "Three-Dimensional Structural Strain Measurement with the Use of Fiber-Optic Sensors." Transportation Research Record: Journal of the Transportation Research Board 1596, no. 1 (January 1997): 45–50. http://dx.doi.org/10.3141/1596-07.

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Three-dimensional strain sensing inside a structure is not feasible with conventional strain sensing techniques such as electrical strain gauges, which are limited to surface measurements. Three-dimensional strain measurement inside a structure would find uses in a variety of new applications: enhanced understanding and detection of composite failure modes, such as delamination; sensing for adaptive structural control; intelligent vehicle highway systems; and structural health monitoring systems for civil structures. The latter application could involve remotely monitoring structural integrity during and after an earthquake, for example. A fiber-optic strain sensor array (FOSSA) in a planar, patch-like configuration was developed, and accurate measurement of the three principal strains inside a simple structure was demonstrated. The planar configuration was chosen to avoid the difficulty and structural degradation of embedding optical sensors in three planes. Two extrinsic Fabry-Perot interferometric (EFPI) sensors and one polari-metric sensor form the planar sensor array. The two EFPI sensors were placed perpendicular to each other in the sensor plane to extract the two normal strain components along the x and y axes. The polarimetric sensor embedded in the plane was used to extract the third normal strain acting on the z axis. The sensor array was embedded in an epoxy resin cube and loaded to 454 kg (1,000 1b) with a loading machine. The strains that were measured correlated well with the external strains measured with surface-bonded electrical strain gauges. The variation in measured strain between the two sensor systems was less than 4 percent for all three principal axes.

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Li, Dan, Chunhee Cho, and Yang Wang. "Patch antenna sensor rosettes for surface strain measurement." Proceedings of the Institution of Civil Engineers - Smart Infrastructure and Construction 170, no. 2 (June 2017): 39–49. http://dx.doi.org/10.1680/jsmic.17.00004.

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Trummer, G., K. Six, C. Marte, A. Meierhofer, and C. Sommitsch. "Automated Measurement of Near-Surface Plastic Shear Strain." International Journal of Railway Technology 3, no. 3 (2014): 1–16. http://dx.doi.org/10.4203/ijrt.3.3.1.

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Dvornikov, A. G., and R. A. Mikheev. "Use of special surface directions in strain measurement." Measurement Techniques 32, no. 5 (May 1989): 442–43. http://dx.doi.org/10.1007/bf00866222.

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Piccolo, Arianna, Yann Lecieux, Sylvie Lesoille, Pierre Teixeira, Johan Bertrand, and Dominique Leduc. "Performance Assessment of Distributed Strain Sensing Techniques for Convergence Monitoring of Radioactive Waste Repository." Sensors 23, no. 1 (December 30, 2022): 398. http://dx.doi.org/10.3390/s23010398.

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This paper presents the measurement methodology of diameter reduction monitoring of micro-tunnel structures used for radioactive waste storage based on distributed strain measurements along fiber optic sensors installed on the circumference. The whole measurement procedure is described: the calibration of the sensors for use in harsh environment (temperature and radioactivity), the measurement analysis technique, the performance assessment of different measurement systems on a surface mock-up and the in-situ validation on an underground structure. The performances of Brillouin and Rayleigh backscattering measurements are compared, as well as different fixation technologies. Distributed measurements are compared to alternative measurements: displacement sensors, Bragg grating extensometers and MEMS accelerometers. The distributed Rayleigh backscattering measurement performed on optical cables bonded to the surface of the structure appears to be the best solution for monitoring the convergence of micro-tunnels and offers comparable performance to alternative technologies tested on the surface demonstrator.

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KAMAYA, Masayuki. "Growth Monitoring of Internal Surface Crack by Strain Measurement of External Surface (Part I: Development of Multiple Strain Measurement Method)." TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series A 77, no. 783 (2011): 2001–11. http://dx.doi.org/10.1299/kikaia.77.2001.

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Devivier, C., Daniel Thompson, Fabrice Pierron, and M. R. Wisnom. "Correlation between Full-Field Measurements and Numerical Simulation Results for Multiple Delamination Composite Specimens in Bending." Applied Mechanics and Materials 24-25 (June 2010): 109–14. http://dx.doi.org/10.4028/www.scientific.net/amm.24-25.109.

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This paper studies the effect of delaminations on strain maps for a simple cantilever beam. The aim is to build an experimental set-up which allows detecting very slight modifications in the strain maps. The case studied is a single delamination on the mid-plane. The measurement method is the deflectometry technique which enables direct slope measurements on a reflective specimen. The comparison with finite element models clearly indicated that the surface strains bear the information of the extent of the delamination. The second step is to use these surface strains to identify a stiffness reduction map for real impact damages.

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Jung, Dal Woo, Il Bum Kwon, and Nak Sam Choi. "Application of a Temperature-Compensating FBG Sensor to Strain Measurement." Advanced Materials Research 26-28 (October 2007): 1089–92. http://dx.doi.org/10.4028/www.scientific.net/amr.26-28.1089.

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A temperature-compensating fiber Bragg grating(FBG) sensor having two different FBGs in one fiber line was applied to the real time measurement of mechanical normal strain in structures. Measurement of mechanical strains of the aluminum beam surface by the double FBG sensor was performed under various thermal conditions, which was compared with results of electrical resistance strain gage. The FBG sensor fabricated in this study could detect accurately values of mechanical strains without containing any thermal strain component.

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Ling, Hang Yin, Alan Kin Tak Lau, Li Cheng, J. Wei, R. S. Thomson, and M. L. Scott. "An Embedded FBG Sensor for Dynamic Strain Measurement for a Clamped-Clamped Composite Structure." Key Engineering Materials 295-296 (October 2005): 21–26. http://dx.doi.org/10.4028/www.scientific.net/kem.295-296.21.

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A comparison of strain measurement results, from an embedded fibre-optic Bragg grating (FBG) sensor and surface mounted strain gauge, at different vibration frequency ranges and using a clamped-clamped glass fibre composite beam, is presented. It is shown that the FBG sensor is able to precisely measure the peaks at the first-two natural frequency modes compared with the spectrum captured from the strain gauge. The results also demonstrate that the strains measured from the FBG sensor agreed well with the strain gauge at frequencies below 100 Hz. Beyond this value, the actual strain on the beam surface was less than 3µe, and the data extracted from the strain gauge are no longer valid. For a clamped-clamped structure, the longitudinal strain of the beam correlates to its vibration amplitude and excitation frequency. Increasing the frequency results in decreasing the longitudinal strain of the beam and erroneous measurements from the strain gauge resulted. This study provides important information on the feasibility of using embedded FBG sensors as vibration monitoring devices to measure mechanical performance of composite structures.

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Monir, Hamed Esmaeili, Hiroshi Yamada, Noriyuki Sakata, Yasuyuki Morita, and Yutaka Nakashima. "4F4 Measurement of strain distribution on human aortic wall surface with a plaque under uniaxial stretch." Proceedings of Conference of Kyushu Branch 2014 (2014): _4F4–1_—_4F4–2_. http://dx.doi.org/10.1299/jsmekyushu.2014._4f4-1_.

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Schenuit, Eduard, Rainer Bolkart, Thomas Becker, and Oliver Spinka. "Optical Strain Measurement on Small Specimens Based on Laser Speckles." Materials Science Forum 584-586 (June 2008): 237–42. http://dx.doi.org/10.4028/www.scientific.net/msf.584-586.237.

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Progresses in developments of high resolution digital cameras and processors power as well enable the use of optical systems for axial and biaxial strain measurements. The main benefit of these systems is a contact free measurement on the sample surface without any influence to the sample. The commonly used optical systems based on following markings attached to sample surface which have to be applied before testing. This paper presents an alternative optical measuring system using the speckle-correlation-technique. The laser based method does not need any special sample markings before testing. The speckle correlation in the presented extensometer measures up to two-dimensional surface strains in tensile as well as in compression tests; original gauge lengths down to 1.5 mm are supported.

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da Fonseca, Joao Quinta, Michael Preuss, P. Ryan, and Philip J. Withers. "Mechanical Property Mapping Using Image Correlation and Electronic Speckle Interferometry." Applied Mechanics and Materials 1-2 (September 2004): 147–52. http://dx.doi.org/10.4028/www.scientific.net/amm.1-2.147.

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By combining modern surface strain measurement techniques with the traditional tensile test mechanical test, a method has been developed whereby the mechanical properties of a test sample with a heterogeneous microstructure such can be characterised in one test. In this paper the applicability to such a method of two such surface strain measurement techniques, image correlation (IC) and electronic speckle pattern interferometry (ESPI), is assessed. Two commercially available systems were used to monitor, simultaneously, the surface strain on tensile test specimens during testing. Measurements on homogeneous samples were compared with measurements made using strain gauges and excellent agreement was found. Elastic modulus and proof stress values measured in these standard samples showed that the uncertainty in the measurements was below 10%. The method was then applied to an inertia friction weld, whose strength varied linearly as a function of distance from the weld line. The values of proof stress obtained were compared with micro-hardness measurements.

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Kalyanasundaram, Shankar, Paul Compston, and Joel Gresham. "A Methodology for Real Time Surface Strain Measurement for Stamping Through Non-Contact Optical Strain Measurement System." Key Engineering Materials 344 (July 2007): 855–61. http://dx.doi.org/10.4028/www.scientific.net/kem.344.855.

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The quality of stamp formed parts depends on a number of variables. Numerical studies based on finite element analysis can provide evolution of strain during forming and correlate with different failures of the formed parts. This study presents a methodology of capturing the evolution of strain during forming through a photogrammetric method. An open die was used to monitor the strain evolution of domed parts. The forming characteristic of a fibre-metal laminate system was compared to a monolithic aluminum alloy to elucidate the differences in the strain evolution during forming. It was found that the two materials exhibited different strain evolution during forming and this affected the failure behavior of the formed parts.

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Schäfer, Karlheinz, and Stefan Keil. "Measurement of tectonic rock strain in Iceland." CATENA 15, no. 3-4 (June 1988): 207–16. http://dx.doi.org/10.1016/0341-8162(88)90045-8.

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Ogawa, Masaru, and Takehiro Ishii. "OS3-2 Evaluation of Three-dimensional Residual Stresses for a Butt-welded Plate via X-ray Measurements on Surface(Stress/strain evaluation,OS3 Stress/strain analyses by diffraction method,MEASUREMENT METHODS)." Abstracts of ATEM : International Conference on Advanced Technology in Experimental Mechanics : Asian Conference on Experimental Mechanics 2015.14 (2015): 36. http://dx.doi.org/10.1299/jsmeatem.2015.14.36.

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Arthington, M. R., C. R. Siviour, N. Petrinic, and B. C. F. Elliott. "Optical surface profile tracking for high-resolution strain measurement." Measurement Science and Technology 22, no. 2 (January 18, 2011): 025304. http://dx.doi.org/10.1088/0957-0233/22/2/025304.

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Sugiyama, Shin, Renji Naruse, and Yaroslav D. Murav’yev. "Surface strain anomaly induced by the storage and drainage of englacial water in Koryto glacier, Kamchatka, Russia." Annals of Glaciology 40 (2005): 232–36. http://dx.doi.org/10.3189/172756405781813627.

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AbstractTo investigate short-term flow-pattern variations of a temperate glacier, longitudinal surface strain was measured with a wire strainmeter in the ablation area of Koryto glacier, Kamchatka, Russia. Strain-rate anomalies were observed in late summer 2000 that were triggered by a water overflow from a moulin near the measurement site followed by the drainage of accumulated water. The strain event started with (compressive) strain rates of >–10–3 d–1 lasting for 6 hours, which then became tensile. Similar strain-rate variations were observed again on the next day. During the event, basal sliding speed measured at the margin in the lower reach of the glacier fluctuated by about ±50% of the daily mean. Smaller and larger sliding speeds corresponded to the compressive and tensile surface strains, respectively. These measurements suggest that the storage and sudden drainage of water caused spatially non-uniform water-pressure fluctuations along the glacier, changing the sliding regime over short time periods.

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Hirose, Y., N. Takano, Y. Nanayama, and T. Mura. "The Thickness Measurements of Thin Bulk Film by X-ray Method." Advances in X-ray Analysis 34 (1990): 567–75. http://dx.doi.org/10.1154/s0376030800014889.

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There are many investigations about thin film. However, these are limited to the surface layer thin film on substrates. It Is very important to know the characteristics of the extremely thin film itself such as surface layer thin film.In the present paper, the first part deals with the thickness measurements of the surface layer film and substrate by means of x-ray method, and then the measurement method of their stress - strain curves and the procedure of the measurement are described. The results obtained are discussed on the basis of their stress — strain curves.

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CHOI, NAK-SAM, and DAL-WOO JUNG. "A CALIBRATION METHOD OF MECHANICAL STRAINS FROM A TEMPERATURE-COMPENSATING FBG SENSOR." Modern Physics Letters B 22, no. 11 (May 10, 2008): 1111–15. http://dx.doi.org/10.1142/s0217984908015929.

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The sensitivity of a temperature-compensating fiber Bragg grating (FBG) sensor which has different FBGs in one fiber line was analyzed for the real time measurement of mechanical normal strain in structures. Measurement of mechanical strains of the aluminum beam surface by the double FBG sensor was performed under various heating rates and temperature range. The results were compared with those of an electrical resistance strain gage. A considerable delay in the strain measurement by the double FBG sensor during the heating process was shown, which could be quantified for the strain compensation by the introduction of a strain retardation factor to the FBG sensor.

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Li, Da Cheng, Jin Liang, Hao Hu, Zheng Zong Tang, Xiang Guo, and Lei Gang Li. "Strain Measurement for Sheet Metal Forming Based on Close Range Photogrammetry." Applied Mechanics and Materials 475-476 (December 2013): 148–55. http://dx.doi.org/10.4028/www.scientific.net/amm.475-476.148.

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To improve efficiency and automation of the 3D full-field surface strain measurement for sheet metal forming, a new grid strain measuring scheme was developed based on the close-range photogrammetry technology. A Local Canny Detector algorithm was proposed for grid nodes and coded targets detection. A 10-parameters nonlinear camera model and the bundle adjustment algorithm were used to optimize the calibration parameters. A multi-epipolar constraint method was employed for grid node matching. Finally, the surface strains were calculated according to the changes of the grid sizes. To evaluate the performance of the proposed scheme, a stamping forming experiment was conducted. Experimental results show that the scheme can provide a non-contact, intuitive and effective solution for strain measurement in sheet metal forming process.

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Steck, R., C. Gatzka, E. Schneider, P. Niederer, and M. L. Tate. "Measurement of bone surface strains on the sheep metacarpus in vivo and ex vivo." Veterinary and Comparative Orthopaedics and Traumatology 16, no. 01 (2003): 38–43. http://dx.doi.org/10.1055/s-0038-1632754.

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SummaryBone surface strains were measured on the dorsal ovine metacarpus during normal locomotion on a treadmill at different walking speeds to determine physiological strain levels. These measured strains were related to the strains measured in an ex vivo model of the sheep forelimb with two types of load application: loading by two Schanz-screws and loading via the radius. In vivo, the average surface strains were found to be dependent upon body weight as well as the walking speed. The orientation of the peak principal strain corresponded to the longitudinal axis of the bone. Ex vivo, loads applied via Schanz screws in the screw-loading model lead to strains on the dorsal metacarpus that corresponds to strains experienced in vivo during intermittent peak loads. Screw loading imparted primarily a bending load to the metacarpus, with the dorsal aspect in compression and the palmar aspect in tension. Loads, applied via the radius and the hoof in the radius-loading model, resulted in bone surface strains comparable to those measured during slow walking in vivo. In both ex vivo loading situations, peak strain orientation was parallel to the longitudinal axis of the sheep metacarpus. In conclusion, the results show that although the ex vivo loading models do not exactly replicate the load experienced in vivo, the magnitude and orientation of the principal strains on the dorsal metacarpus are within the range of strains occurring during normal physiological loading. These data validate the physiological significance of the ex vivo model and aid in understanding effects of mechanical loading on interstitial fluid flow and mass transport through bone.

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Kang, J., M. Jain, D. S. Wilkinson, and J. D. Embury. "Microscopic Strain Mapping Using Scanning Electron Microscopy Topography Image Correlation at Large Strain." Journal of Strain Analysis for Engineering Design 40, no. 6 (August 1, 2005): 559–70. http://dx.doi.org/10.1243/030932405x16151.

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Measuring the distribution of local strain at the microscopic level is a challenging problem, especially for materials subjected to large overall strain. In the present study, a novel microscopic strain mapping technique has been developed based on the analysis of surface topography using digital image correlation (DIC) software. The input is a series of scanning electron microscopy (SEM) images. The method uses topographic features (such as surface slip traces) found in these images as the input. A commercially available optical strain measurement system (ARAMIS®, which is a trade name of the equipment from GOM mbH, Braunschweig, Germany) that utilizes the DIC methodology is used for this purpose. It was found that the best results were obtained using an incremental approach in which DIC is used to map the local strain increments following a modest amount of macroscopic deformation. This is essential when using topographic features such as slip traces that are not static. The accuracy and scale of the measurements are affected by image and facet size. The method has been validated, based on in situ deformation of an aluminium alloy within an SEM, using strains measured independently by means of surface indents. The results clearly reveal the details of the local shear on a sub-grain-size scale and the evolution of shear bands within the necking area, leading to local strains that exceed the average strain by a factor of 2.3.

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KAMAYA, Masayuki, Masahiro KAWAKUBO, and Akira KIUCHI. "Growth Monitoring of Internal Surface Crack by Strain Measurement of External Surface (Part II: Fatigue Crack Growth Monitoring by Multiple Strain Measurement Method)." TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series A 77, no. 783 (2011): 2012–25. http://dx.doi.org/10.1299/kikaia.77.2012.

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Ma, Zhen, and Xiyuan Chen. "Verification of Strain Transfer Characteristics of Distributed Surface-attached FBGs on Aircraft Wings." MATEC Web of Conferences 306 (2020): 05001. http://dx.doi.org/10.1051/matecconf/202030605001.

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In order to provide higher accuracy for transfer alignment on aircraft, a surface-attached FBGs is designed for distributed deformation measurement of aircraft wing. To verify the measurement accuracy of the surface-attached FBGs, a strain calibration method of the surface-attached FBGs applied with the wing strain measurement is proposed. Two Aluminium Alloy Test Plates(AATP) with different sizes were designed as the matrix material for tensile test. The test results show that AATP-A has better test effect. Through the two sets of tensile tests, the change of wavelength measured on the surface-attached FBGs is in good agreement with the change of strain value of strain gauge.The experimental results prove that the method based on surface-attached FBGs is feasible for the strain measurement of aircraft wing. The method is simple and reliable, which lays a foundation for the follow-up study of the full-field deformation measurement of aircraft wing.

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Pilch, Alan, Ajay Mahajan, and Tsuchin Chu. "Measurement of Whole-Field Surface Displacements and Strain Using a Genetic Algorithm Based Intelligent Image Correlation Method." Journal of Dynamic Systems, Measurement, and Control 126, no. 3 (September 1, 2004): 479–88. http://dx.doi.org/10.1115/1.1789968.

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This paper presents an intelligent digital image correlation technique that uses genetic algorithms to measure surface displacements and strains. Speckle patterns are spray painted on the surface of interest and pictures taken before and during loading. Subpixel resolution, required for measuring displacements and strains accurately, is obtained by using interpolation methods. An innovative procedure based on genetic algorithms (GA) is used that has the potential to give the two displacements and four deformation gradients directly for a subset being investigated. This paper presents the algorithm for the six variables, but uses only the displacements (two variables) to calculate the 2-D strain fields. The genetic algorithms can guarantee a solution based on a comprehensive calibration procedure. The focus of this paper is the description of the GA routine used for the search process as well as the calibration scheme. Measurement results are presented for rigid-body displacement, 1-D and 2-D strain as proof of concept. Some potential applications for this work are to extract surface displacements and strains on the surfaces of aircraft, spacecraft and reusable launch vehicles, submarine and ship hulls, civil infrastructures such as bridges, dams and buildings, and biomedical imaging applications.

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Wang, Christopher C.-B., Jian-Ming Deng, Gerard A. Ateshian, and Clark T. Hung. "An Automated Approach for Direct Measurement of Two-Dimensional Strain Distributions Within Articular Cartilage Under Unconfined Compression." Journal of Biomechanical Engineering 124, no. 5 (September 30, 2002): 557–67. http://dx.doi.org/10.1115/1.1503795.

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An automated approach for measuring in situ two-dimensional strain fields was developed and validated for its application to cartilage mechanics. This approach combines video microscopy, optimized digital image correlation (DIC), thin-plate spline smoothing (TPSS) and generalized cross-validation (GCV) techniques to achieve the desired efficiency and accuracy. Results demonstrate that sub-pixel accuracies can be achieved for measuring tissue displacements with this methodology with a measurement uncertainty ranging from 0.25 to 0.30 pixels. The deformational gradients (from which the strains are determined) can be evaluated directly using the optimized DIC, with a measurement uncertainty of 0.017∼0.032. In actual measurements of strain in cartilage, TPSS and differentiation can be used to achieve a more accurate measurement of the gradients from the displacement data. Using this automated approach, the two-dimensional strain fields inside immature bovine carpometacarpal joint cartilage specimens under unconfined compression were characterized n=21. The depth-dependent apparent elastic modulus and Poisson’s ratio were also determined and found to be smallest at the articular surface and increasing with depth. The apparent Poisson’s ratio is found to decrease with increasing compressive strain, with values as low as 0.01 observed near the articular surface at 25% compression. The variation of the apparent Poisson’s ratio with depth is found to be consistent with a theoretical model of cartilage which accounts for the disparity in its tensile and compressive moduli.

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Rahimi, S., and I. Violatos. "Comparison Between Surface and Near-Surface Residual Stress Measurement Techniques Using a Standard Four-Point-Bend Specimen." Experimental Mechanics 62, no. 2 (October 7, 2021): 223–36. http://dx.doi.org/10.1007/s11340-021-00779-6.

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Abstract Background Determination of near-surface residual stresses is challenging for the available measurement techniques due to their limitations. These are often either beyond reach or associated with significant uncertainties. Objective This study describes a critical comparison between three methods of surface and near-surface residual stress measurements, including x-ray diffraction (XRD) and two incremental central hole-drilling techniques one based on strain-gauge rosette and the other based on electronic speckle pattern interferometry (ESPI). Methods These measurements were performed on standard four-point-bend beams of steel loaded to known nominal stresses, according to the ASTM standard. These were to evaluate the sensitivity of different techniques to the variation in the nominal stress, and their associated uncertainties. Results The XRD data showed very good correlations with the surface nominal stress, and with superb repeatability and small uncertainties. The results of the ESPI based hole-drilling technique were also in a good agreement with the XRD data and the expected nominal stress. However, those obtained by the strain gauge rosette based hole-drilling technique were not matching well with the data obtained by the other techniques nor with the nominal stress. This was found to be due to the generation of extensive compressive residual stress during surface preparation for strain gauge installation. Conclusion The ESPI method is proven to be the most suitable hole-drilling technique for measuring near-surface residual stresses within distances close to the surface that are beyond the penetration depth of x-ray and below the resolution of the strain gauge rosette based hole-drilling method.

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Caine, Michael P., Gihan S. Amarasiriwardena, and Daniel T. Toon. "E6 Measurement of 3D surface strain in soft sporting goods using athletic footwear as an exemplar(English session)." Proceedings of the Symposium on sports and human dynamics 2010 (2010): 476–78. http://dx.doi.org/10.1299/jsmeshd.2010.476.

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Khoo, Sze-Wei, Saravanan Karuppanan, and Ching-Seong Tan. "A Review of Surface Deformation and Strain Measurement Using Two-Dimensional Digital Image Correlation." Metrology and Measurement Systems 23, no. 3 (September 1, 2016): 461–80. http://dx.doi.org/10.1515/mms-2016-0028.

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Abstract Among the full-field optical measurement methods, the Digital Image Correlation (DIC) is one of the techniques which has been given particular attention. Technically, the DIC technique refers to a non-contact strain measurement method that mathematically compares the grey intensity changes of the images captured at two different states: before and after deformation. The measurement can be performed by numerically calculating the displacement of speckles which are deposited on the top of object’s surface. In this paper, the Two-Dimensional Digital Image Correlation (2D-DIC) is presented and its fundamental concepts are discussed. Next, the development of the 2D-DIC algorithms in the past 33 years is reviewed systematically. The improvement of 2DDIC algorithms is presented with respect to two distinct aspects: their computation efficiency and measurement accuracy. Furthermore, analysis of the 2D-DIC accuracy is included, followed by a review of the DIC applications for two-dimensional measurements.

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MIURA, Nagisa, Motoko MURAKAMI, Miyako KOIKE, Shuichi ARIKAWA, Satoru YONEYAMA, and Osamu TANNO. "Strain Measurement on Facial Skin Surface Using 3D Digital Image Correlation (Strain and Morphology on Facial Skin Surface)." TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series A 79, no. 802 (2013): 774–78. http://dx.doi.org/10.1299/kikaia.79.774.

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KAWASHIMA, Ikuo, and Shunsuke SAKURAI. "Consideration of strain measurement errors measured by strain gauges placed on a curved surface." Doboku Gakkai Ronbunshu, no. 454 (1992): 127–30. http://dx.doi.org/10.2208/jscej.1992.454_127.

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TAKAKI, Takeshi, Seiji TANOUE, Shuji UEMOTO, Noriyuki MIYAMOTO, Tadayoshi AOYAMA, and Idaku ISHII. "2A2-P24 Concrete surface strain measurement using a strain visualization sticker(Non-contact Sensing)." Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2013 (2013): _2A2—P24_1—_2A2—P24_3. http://dx.doi.org/10.1299/jsmermd.2013._2a2-p24_1.

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Pryor, J. Luke, Riana R. Pryor, Andrew Grundstein, and Douglas J. Casa. "The Heat Strain of Various Athletic Surfaces: A Comparison Between Observed and Modeled Wet-Bulb Globe Temperatures." Journal of Athletic Training 52, no. 11 (November 1, 2017): 1056–64. http://dx.doi.org/10.4085/1062-6050-52.11.15.

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Context: The National Athletic Trainers' Association recommends using onsite wet-bulb globe temperature (WBGT) measurement to determine whether to modify or cancel physical activity. However, not all practitioners do so and instead they may rely on the National Weather Service (NWS) to monitor weather conditions. Objective: To compare regional NWS WBGT estimates with local athletic-surface readings and compare WBGT measurements among various local athletic surfaces. Design: Observational study. Setting: Athletic fields. Main Outcome Measure(s): Measurements from 2 identical WBGT devices were averaged on 10 athletic surfaces within an NWS station reporting radius. Athletic surfaces consisted of red and black all-weather tracks (track), blue and black hard tennis courts (tennis), nylon-knit artificial green turf, green synthetic turfgrass, volleyball sand, softball clay, natural grass (grass), and a natural lake (water). Measurements (n = 143 data pairs) were taken over 18 days (May through September) between 1 pm and 4:30 pm in direct sunlight 1.2 m above ground. The starting location was counterbalanced across surfaces. The NWS weather data were entered into an algorithm to model NWS WBGT. Results: Black tennis, black track, red track, and volleyball sand WBGT recordings were greater than NWS estimates (P ≤ .05). When all athletic-surface measurements were combined, NWS (26.85°C ± 2.93°C) underestimated athletic-surface WBGT measurements (27.52°C ± 3.13°C; P < .001). The range of difference scores (−4.42°C to 6.14°C) and the absolute mean difference (1.71°C ± 1.32°C) were large. The difference between the onsite and NWS WBGT measurements resulted in misclassification of the heat-safety activity category 45% (65/143) of the time (= 3.857, P = .05). The WBGT of water was 1.4°C to 2.7°C lower than that of all other athletic surfaces (P = .04). We observed no other differences among athletic surfaces but noted large WBGT measurement variability among athletic playing surfaces. Conclusions: Clinicians should use an onsite WBGT device to determine environmental conditions and the need for modification of athletic events, especially as environmental conditions worsen. Given the large WBGT variability among athletic surfaces, WBGT measurements should be obtained from each athletic surface.

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Yang, J. L., H. Baillères, T. Okuyama, A. Muneri, and G. Downes. "Measurement methods for longitudinal surface strain in trees: a review." Australian Forestry 68, no. 1 (January 2005): 34–43. http://dx.doi.org/10.1080/00049158.2005.10676224.

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Manthey, D. W., and D. Lee. "Recent developments in a vision-based surface strain measurement system." JOM 47, no. 7 (July 1995): 46–49. http://dx.doi.org/10.1007/bf03221231.

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Han, H. C., and Y. C. Fung. "Direct measurement of transverse residual strains in aorta." American Journal of Physiology-Heart and Circulatory Physiology 270, no. 2 (February 1, 1996): H750—H759. http://dx.doi.org/10.1152/ajpheart.1996.270.2.h750.

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Residual strains were measured in the porcine aorta. Segments were cut from the aorta perpendicular to its longitudinal axis. Microdots of water-insoluble black ink were sprinkled onto the transverse sectional surface of the segments in the no-load state. The segments were then cut radially, and sectional zero-stress states were approached. The coordinates of selected microdots (2-20 microns) were digitized from photographs taken in the no-load state and the zero-stress state. Residual strains in the transverse section were calculated from the displacement of the microdots. The circumferential residual strains on the inner wall and outer wall were calculated from the circumferential lengths in the no-load state and the zero-stress state. Results show that the circumferential residual strain is negative (compressive) in the inner layer of the aortic wall and positive (tensile) in the outer layer, whereas the radial residual strain is tensile in the inner layer and compressive in the outer layer. This residual strain distribution reduces the stress concentration in the aorta under physiological load. The experimental results compared well with theoretical estimations of a cylindrical model. Regional difference of the residual strain exists and is significant (P < 0.01), e.g., the circumferential residual strains on the inner wall of the ascending, descending thoracic, and abdominal regions of the aorta are -0.133 +/- 0.019, -0.074 +/- 0.020, and -0.046 +/- 0.017 (mean +/- SD), respectively. More radial cuts of a segment produced no significant additional strains. This means that an aortic segment after one radial cut can be considered as the zero-stress state.

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Wong, R. H. C., Y. S. H. Guo, K. T. Chau, Wei Shen Zhu, and Shu Cai Li. "The Crack Growth Mechanism from 3-D Surface Flaw with Strain and Acoustic Emission Measurement under Axial Compression." Key Engineering Materials 353-358 (September 2007): 2357–60. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.2357.

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This paper presents the crack growth mechanism from a 3-D surface flaw on gabbro specimens using strain measurement and acoustic emission (AE) technique. Based on the results of strain and AE measurement, microcracks initiated inside the rock and extend to the surface of the specimen. With the observation from the measurements, four types of crack patterns initiate wing crack, anti-wing crack (opposite direction of wing crack), petal crack and compressive crack. The strain values of anti-wing cracks are larger 1 to 2 times than that of wing crack. The AE energy release from anti-wing crack is higher 2.5 times than that of wing crack, while the energy release form wing crack is the least but the compressive crack is the highest. Thus, the appearance of initiation and propagation of the anti-wing crack and compressive crack are very actively than that of the wing crack. The strain and AE measurement is not only to provide a clear concept on the mechanisms of crack growth form a 3-D surface flaw but also to provide useful knowledge on the AE property of the crack patterns.

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Hlebová, Stanislava, Ľubomír Ambriško, and Ladislav Pešek. "Strain Measurement in Local Volume by Non-Contact Videoextensometric Technique on Ultra High Strength Steels." Key Engineering Materials 586 (September 2013): 129–32. http://dx.doi.org/10.4028/www.scientific.net/kem.586.129.

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The paper presents the results of strain measurement using two methods: videoextensometry (ME46) and digital image correlation (DIC)-ARAMIS. ME46 - allows measuring and monitoring the major and minor strain on a planar surface of a loaded object [1]. Experimental equipment uses a CCD camera for monitoring the process. The software calculates the displacements of contrast dots and subsequently the strain components are obtained. Another method for non-contact measurements is DIC technique; the measurements are done using three-dimensional image correlation system. The system uses two digital high-speed cameras providing a synchronized stereo view of the specimen where speckles are arranged on the surface. The results show the complete strain field during the tests, including details of the strain field when necking develops prior to the failure [2]. Experimental results obtained on ultra high strength automotive steels DP 1000 and 1400M grades during static tensile test are presented in the paper. The outputs of both are deformation maps. Advantages and disadvantages of both methods are compared.

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Kozubowski, J. A., W. W. Gerberich, and T. Stefanski. "Measurement of small elastic strains in silicon using electron channeling patterns." Journal of Materials Research 3, no. 4 (August 1988): 710–13. http://dx.doi.org/10.1557/jmr.1988.0710.

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A silicon single-crystal slab 0.15 mm in thickness was bent to produce small, nonuniform surface strains of the order of 0.2%. The electron channeling patterns were observed in a JSM 840 SEM (scanning electron microscope) at an accelerating voltage close to 25 kV. Proper choice of the triangles formed by intersecting channeling lines of zero-order and of higher-order Laue zones allows one to measure the changes in their dimensions caused by imposed strain. It was estimated that the lower limit of detectable elastic strain is close to 0.1%. The possibilities of using this method for estimation of the average elastic strains in thin epitaxial layers are discussed.

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Weisman, R. Bruce, Sergei M. Bachilo, Wei Meng, and Satish Nagarajaiah. "(Invited) Camera-Based Strain Visualization Using Carbon Nanotube Fluorescence." ECS Meeting Abstracts MA2022-01, no. 9 (July 7, 2022): 754. http://dx.doi.org/10.1149/ma2022-019754mtgabs.

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It is well known that each semiconducting species of single-wall carbon nanotube (SWCNT) gives distinct near-infrared fluorescence following excitation with visible light. Fundamental band gap modulation makes the peak emission wavelengths shift predictably when the nanotubes are deformed by axial stretching or compression. This effect forms the basis for a new method of mechanical strain measurement in which nanotubes are dilutely dispersed in thin polymer films applied to surfaces of interest. When the substrate is subsequently strained, load transfer through the film to the nanotubes causes small spectral shifts that are monitored through non-contact spectral measurements. We have demonstrated this method through successful strain mapping on specimens of aluminum, copper, steel, acrylic, polycarbonate, cement, and concrete, using point-by-point scanning. To improve the speed and convenience of SWCNT-based strain mapping, we are adapting the method to camera-based measurements. A macroscopic region of a coated specimen surface is illuminated with an excitation laser and the resulting SWCNT emission is imaged from a stand-off distance of ca. 50 cm by a near-IR sensitive camera. Multiple images are acquired through a tunable spectral filter to span the emission band of interest. The image data are then analyzed by spectrally fitting intensities at each pixel to find the local peak emission wavelength, from which the local strain value is deduced. The set of local strains is converted into a color-coded strain map showing detailed deformations of the specimen. We expect that the introduction of camera-based spectral strain measurement technology will lead to an important industrial application of SWCNTs.

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Journal articles on the topic 'Surface strain measurement'

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