Journal articles: 'Strain analysis technique'

1

Srinivasan, S., F. Kallel, R. Souchon, and J. Ophir. "Analysis of an Adaptive Strain Estimation Technique in Elastography." Ultrasonic Imaging 24, no. 2 (April 2002): 109–18. http://dx.doi.org/10.1177/016173460202400204.

Full text

Abstract:

Elastography is based on the estimation of strain due to tissue compression or expansion. Conventional elastography involves computing strain as the gradient of the displacement (time-delay) estimates between gated pre- and postcompression signals. Uniform temporal stretching of the postcompression signals has been used to reduce the echo-signal decorrelation noise. However, a uniform stretch of the entire postcompression signal is not optimal in the presence of strain contrast in the tissue and could result in loss of contrast in the elastogram. This has prompted the use of local adaptive stretching techniques. Several adaptive strain estimation techniques using wavelets, local stretching and iterative strain estimation have been proposed. Yet, a quantitative analysis of the improvement in quality of the strain estimates over conventional strain estimation techniques has not been reported. We propose a two-stage adaptive strain estimation technique and perform a quantitative comparison with the conventional strain estimation techniques in elastography. In this technique, initial displacement and strain estimates using global stretching are computed, filtered and then used to locally shift and stretch the postcompression signal. This is followed by a correlation of the shifted and stretched postcompression signal with the precompression signal to estimate the local displacements and hence the local strains. As proof of principle, this adaptive stretching technique was tested using simulated and experimental data.

APA, Harvard, Vancouver, ISO, and other styles

2

Smith Neto, P., E. S. Palma, and V. M. Figueiredo Bicalho. "Stress Analysis in Automobile Components Using Reflexive Photoelasticity Technique." Applied Mechanics and Materials 5-6 (October 2006): 117–24. http://dx.doi.org/10.4028/www.scientific.net/amm.5-6.117.

Full text

Abstract:

The main objective of this work was to introduce Reflexive Photoelasticity Technique in qualifying automotive components at Fiat Automoveis S.A in Brazil. Actual stresses were determined in a simple geometry plate and also in nodes of a body shell of a passenger vehicle by using reflexive photoelasticity methodology. Initially, tests were performed in welded steel plates submitted to traction loads. These plates were previously coated with birrefringent plastic material. External loads were applied through hydraulic MTS actuators. Stress and strain distribution in welded points neighboring areas using reflexive polariscope were quantitative determined. Simultaneously, these stress and strains acting on the welded plate were determined using strain gauges. The results from both experimental techniques (photoelasticity and strain gauges) were compared with those obtained from a numerical model using finite element method. The results were correlated and analyzed. Finally, reflexive photoelasticity technique was used to determine the stresses in nodes of a body shell of a passenger vehicle. Through this analysis it was possible to determine critical points in the structure with peak stresses.

APA, Harvard, Vancouver, ISO, and other styles

3

Bieliková, L., Z. Landa, L. S. Osborne, and V. Čurn. "Characterization and identification of entomopathogenic and mycoparasitic fungi using RAPD-PCR technique." Plant Protection Science 38, No. 1 (January 29, 2012): 1–12. http://dx.doi.org/10.17221/4813-pps.

Full text

Abstract:

Entomopathogenic and mycoparasitic fungi were characterised by RAPD technique, with special attention to evaluate the genetic stability of strains that are used as active ingredients in commercial biopesticides. Strain-specific fingerprints were constructed for Paecilomyces fumosoroseus – strain PFR 97 Apopka, Gliocladium virens – strain GL 21 and Verticillium lecanii – strain MYCOTAL. Genetic stability and homogeneity was confirmed among re-isolates that were obtained from commercial batches of bio-insecticide PFR 97TM 20%WDG and bio-fungicide SoilGardTM12G that had been produced in 1995–1999. RAPD analysis indicated the genetic identity of V. lecanii strains re-isolated from the two different bio-insecticides MYCOTAL<sup>®</sup> and VERTALEC<sup>®</sup>. The usefulness of RAPD technique was demonstrated when P. fumosoroseus strain PFR 97 Apopka was reliably identified after having passed through adults of the spruce bark beetle Ips typographus, and by analysis of the relationship between fungi of the genus Gliocladium.

APA, Harvard, Vancouver, ISO, and other styles

4

Baldwin, J. D., and J. G. Thacker. "A Strain-Based Fatigue Reliability Analysis Method." Journal of Mechanical Design 117, no. 2A (June 1, 1995): 229–34. http://dx.doi.org/10.1115/1.2826127.

Full text

Abstract:

A new fatigue reliability technique has been developed using a strain-based analysis. A probabilistic strain-life curve, where the variability in cycles to failure at constant strain range has been modeled with a three-parameter Weibull distribution, has been incorporated into the strain-based fatigue analysis. This formulation, which includes a notch strain analysis, rainflow cycle counting and damage accumulation according to Miner’s rule, is used to estimate fatigue life to crack initiation for notched components using smooth specimen laboratory data. Unlike other probabilistic fatigue models, the technique developed here does not include a distribution model for stress peaks such as the commonly-used stationary narrow band Gaussian random process assumption but rather uses strain histories directly. Using this model, techniques have been developed to estimate the number of cycles to failure at a specified reliability and to predict the reliability and failure rate at a specified time in the analysis.

APA, Harvard, Vancouver, ISO, and other styles

5

Gallage, Chaminda, and Chamara Jayalath. "Use of Particle Image Velocimetry (PIV) technique to measure strains in geogrids." E3S Web of Conferences 92 (2019): 12007. http://dx.doi.org/10.1051/e3sconf/20199212007.

Full text

Abstract:

Geosynthetics are widely used in Geotechnical Engineering to reinforce soil/gravel in pavements, retaining wall backfills, and embankments. It is important to measure strains in geogrids in the determination of their strength parameters such as tensile strength and secant stiffness, and in evaluating their performances in geogrid-reinforced structures. Strain gauges are commonly used in measuring strains in geogrids. However, it is important to verify the strains measured by strain gauges as these strains are affected by the data logging device, gauge factors, quality of bonding between grain gauge and geogrid, and temperature. Therefore, this study was conducted to verify the performance of strain gauges attached to Geogrids and also to investigate the possibility of using PIV technique and GeoPIV-RG software to measure the local strains developed in a geogrid specimen under tensile testing in the laboratory. In the experimental program of this study, six composite geogrid specimens were tested for tensile strength (wide-width tensile tests) while measuring/calculating its tensile strain by using strain gauges attached to the specimens, Geo-PIV-RG analysis and crosshead movements of Instron apparatus. Good agreement between the strains obtained from strain gauges and geoPIV-RG analysis was observed for all the tests conducted. These results suggest that the PIV technique along with geoPIV-RG program can effectively be used to measure the local strain of geogrids in the laboratory tests. It was also able to verify that properly installed strain gauges are able to measure strain in the geogrids which are used in the field applications.

APA, Harvard, Vancouver, ISO, and other styles

6

Kriven, W. M. "Strain analysis in composite ceramics." Proceedings, annual meeting, Electron Microscopy Society of America 44 (August 1986): 494–97. http://dx.doi.org/10.1017/s0424820100144012.

Full text

Abstract:

Significant progress towards a fundamental understanding of transformation toughening in composite zirconia ceramics was made possible by the application of a TEM contrast analysis technique for imaging elastic strains. Spherical zirconia particles dispersed in a large-grained alumina matrix were examined by 1 MeV HVEM to simulate bulk conditions. A thermal contraction mismatch arose on cooling from the processing temperature of 1500°C to RT. Tetragonal ZrO2 contracted amisotropically with α(ct) = 16 X 10-6/°C and α(at) = 11 X 10-6/°C and faster than Al2O3 which contracted relatively isotropically at α = 8 X 10-6/°C. A volume increase of +4.9% accompanied the transformation to monoclinic symmetry at room temperature. The elastic strain field surrounding a particle before transformation was 3-dimensionally correlated with the internal crystallographic orientation of the particle and with the strain field after transformation. The aim of this paper is to theoretically and experimentally describe this technique using the ZrO2 as an example and thereby to illustrate the experimental requirements Tor such an analysis in other systems.

APA, Harvard, Vancouver, ISO, and other styles

7

Kwon, Young W. "Failure Analysis of Composite Structures Using Multiscale Technique." Materials Science Forum 995 (June 2020): 209–13. http://dx.doi.org/10.4028/www.scientific.net/msf.995.209.

Full text

Abstract:

Failure analyses of laminated fibrous composite structures were conducted using the failure criteria based on a multiscale approach. The failure criteria used the stresses and strains in the fiber and matrix materials, respectively, rather than those smeared values at the lamina level. The failure modes and their respective failure criteria consist of fiber failure, matrix failure and their interface failure explicitly. In order to determine the stresses and strains at the constituent material level (i.e. fiber and matrix materials), analytical expressions were derived using a unit-cell model. This model was used for the multiscale approach for both upscaling and downscaling processes. The failure criteria are applicable to both quasi-static loading as well as dynamic loading with strain rate effects.

APA, Harvard, Vancouver, ISO, and other styles

8

Elmahdy, Ahmed, and Patricia Verleysen. "Challenges related to testing of composite materials at high strain rates using the split Hopkinson bar technique." EPJ Web of Conferences 183 (2018): 02021. http://dx.doi.org/10.1051/epjconf/201818302021.

Full text

Abstract:

The design of sample geometries and the measurement of small strains are considered the main challenges when testing composite materials at high strain rates using the split Hopkinson bar technique. The aim of this paper is to assess two types of tensile sample geometries, namely dog-bone and straight strip, in order to study the tensile behaviour of basalt fibre reinforced composites at high strain rates using the split Hopkinson bar technique. 2D Digital image correlation technique was used to study the distribution of the strain fields within the gauge section at quasi-static and dynamic strain rates. Results showed that for the current experiments and the proposed clamping techniques, both sample geometries fulfilled the requirements of a valid split Hopkinson test, and achieved uniform strain fields within the gauge section. However, classical Hopkinson analysis tends to overestimate the actual strains in the gauge section for both geometries. It is, therefore, important to use a local deformation measurement when using these 2 geometries with the proposed clamping technique.

APA, Harvard, Vancouver, ISO, and other styles

9

Dasgupta, A., C. Oyan, D. Barker, and M. Pecht. "Solder Creep-Fatigue Analysis by an Energy-Partitioning Approach." Journal of Electronic Packaging 114, no. 2 (June 1, 1992): 152–60. http://dx.doi.org/10.1115/1.2906412.

Full text

Abstract:

This study explores the possibility of using a unified theory of creep-fatigue, similar to the Halford-Manson strain-range partitioning method, for examining the effect of cyclic temperature range on fatigue life, over a wide range of temperatures. Other investigators have attempted similar techniques before for solder fatigue analysis. The present study is different since it proposes an energy-partitioning technique rather than strain-partitioning to examine the dependence of solder fatigue behavior on temperature dependent changes in the relative amounts of plastic and creep strains. The solder microstructure also dictates creep behavior but is assumed to be a given invariant parameter in this study. In other words, this study is targeted at as-cast microstructures and does not address post-recrystallization behavior. A sample solder joint of axisymmetric configuration, commonly found in leaded through-hole mounting technology, is analyzed with the help of nonlinear finite element methods. The strain history is determined for constant-amplitude temperature cycling with linear loading and unloading, and with constant dwells at upper and lower ends of the cycle. Large-deformation continuum formulations are utilized in conjunction with a viscoplastic constitutive model for the solder creep-plasticity behavior. Relevant material properties are obtained from experimental data in the literature. The results show significant amounts of rachetting and shakedown in the solder joint. Detailed stress-strain histories are presented, illustrating the strain amplitude, mean strain and residual stresses and strains. For illustrative purposes, the hysteresis cycles are partitioned into elastic, plastic and creep components. Such partitioned histories are essential in order to implement either the Halford-Manson strain-range partitioning technique or the energy-based approach suggested here, for analyzing the creep-fatigue damage accumulation in solder material. This study also illustrates the role and utility of the finite element method in generating the detailed stress-strain histories necessary for implementing the energy partitioning approach for creep-fatigue damage evaluation. Solder life prediction is presented as a function of cyclic temperature range at a given mean temperature.

APA, Harvard, Vancouver, ISO, and other styles

10

Hu, Shoufeng, and N. J. Pagano. "On the Use of a Plane-Strain Model to Solve Generalized Plane-Strain Problems." Journal of Applied Mechanics 64, no. 1 (March 1, 1997): 236–38. http://dx.doi.org/10.1115/1.2787280.

Full text

Abstract:

Many composite problems are generalized plane strain in nature. They are often solved using three-dimensional finite element analyses. We propose a technique to solve these problems with a plane-strain model, which is achieved by introducing some artificial out-of-plane thermal strains in a two-dimensional finite element analysis. These artificial thermal strains are chosen such that an identical stress field is obtained, while the actual strains and displacements can also be determined.

APA, Harvard, Vancouver, ISO, and other styles

11

Zhang, J., M. Li, C. Y. Xiong, J. Fang, and S. Yi. "Thermal deformation analysis of BGA package by digital image correlation technique." Microelectronics International 22, no. 1 (April 1, 2005): 34–42. http://dx.doi.org/10.1108/13565360510575530.

Full text

Abstract:

PurposeThe mismatch of the thermal expansion coefficients of the materials in multiplayer structure may induce serious stress concentrations in electronic packaging. Experimental evaluation of the thermal stresses and strains in those electronic composites is becoming significantly important for optimizing design and failure prediction of the electronic devices.Design/methodology/approachDigital image correlation (DIC) technique was utilized to obtain thermal deformation filed of a BGA package. With the help of white light to illuminate the cross section of the BGA package, the gray images were taken from the rough surface of the specimen, that offer a kid of carrier pattern for the DIC processing with statistical resemblance in gray distributions. By using the algorithm of correlation computation, the DIC searched the matching spots in a pair of those images in which the spot displacements were involved in between, to obtain the deformation fields of the package specimen caused by temperature changes.FindingsThe results show interesting strain distributions in the assembly. Both the horizontal displacement component and its normal derivative are strongly related to the arrangement of the solder joints in the bonding medium between the die and the ceramic substrate. The strain components in the middle region of the package are larger than those in the side regions where the strain relaxation may exist near the stress‐free boundaries. The shear strain components show special bands of parallel lines with identical amount over the chip‐package to sustain the shearing of the packed structure under thermal loading.Originality/valueThe DIC technique shows to be a useful tool for the thermal strain analysis of the electronic packaging devices. Not only provides it the whole field deformation of the assembly, but also maintains the surface pictures of the package without covering any fringes, which is important to compare the deformation field with the specimen surface to reveal the stain distribution related to the failure prediction of the materials.

APA, Harvard, Vancouver, ISO, and other styles

12

Kharshiduzzaman, M., A. Gianneo, and A. Bernasconi. "Experimental analysis of the response of fiber Bragg grating sensors under non-uniform strain field in a twill woven composite." Journal of Composite Materials 53, no. 7 (August 9, 2018): 893–908. http://dx.doi.org/10.1177/0021998318793183.

Full text

Abstract:

Fiber Bragg grating optical sensors are nowadays widely employed for strain measurement for structural health monitoring and in experimental mechanics. Compared to other techniques, i.e. electrical strain gauges, fiber Bragg grating offer immunity to electromagnetic interference and allow for long transmission lead lines. Moreover, thanks to multiplexing interrogation, several sensors can be photo-imprinted into a single fiber core allowing for strain evaluation at multiple locations simultaneously. They have high adaptability to composite materials, particularly because it is possible to be embedded into laminates without affecting their strength and stiffness. Fiber Bragg grating strain measurements are based on the detection of the wavelength shift of their peak reflected spectrum. However, subjected to strain gradients, the spectral response of fiber Bragg grating sensors may be distorted and the sharp peak may not be retained. In this work, the response of fiber Bragg grating sensors having different grating lengths and bonded to the surface of a carbon fiber-reinforced twill woven laminate was analyzed. The analysis combined transfer matrix (T-matrix) with digital image correlation methods. Digital image correlation technique was used to capture the non-uniform strain fields in the woven composites and measured strains were employed in T-Matrix algorithm to simulate fiber Bragg grating response. Using this approach, the effect of the length of the fiber Bragg grating on the strain measurement is assessed and results discussed. Moreover, it is shown that T-matrix formulation combined with a non-contact strain field measurement technique, as DIC, is an appropriate technique to simulate the behavior of fiber Bragg grating bonded to composite materials of complex microstructure.

APA, Harvard, Vancouver, ISO, and other styles

13

Bicalho, AA, ADCM Valdívia, BCF Barreto, D. Tantbirojn, A. Versluis, and CJ Soares. "Incremental Filling Technique and Composite Material—Part II: Shrinkage and Shrinkage Stresses." Operative Dentistry 39, no. 2 (March 1, 2014): e83-e92. http://dx.doi.org/10.2341/12-442-l.

Full text

Abstract:

SUMMARY Objectives Finite element analysis (FEA) was used to study polymerization shrinkage stress in molars restored with composites and to correlate those stresses with experimentally measured tooth deformation. Methods Three composites (Filtek LS, Aelite LS Posterior, Filtek Supreme) and three filling techniques (bulk, 2.0-mm increments, and 1.0-mm increments) for restoring a molar were simulated in a two-dimensional FEA. Polymerization shrinkage was modeled using post-gel shrinkage, which was measured using the strain gauge technique (n=10). Cuspal tooth deformation, measured at the buccal and lingual surfaces with strain gauges in a laboratory study, was used to validate the analysis. Residual shrinkage stresses were expressed in modified von Mises equivalent stresses. Linear Pearson correlations were determined between the laboratory and FEA results. Results Post-gel shrinkage values (in volume %) were: Filtek LS (0.11 ± 0.03) < Aelite LS Posterior (0.51 ± 0.02) < Filtek Supreme (0.62 ± 0.09). The 1.0-mm increment filling caused substantially higher stresses and strains in the cervical enamel region. Significant correlations were found between: elastic modulus and FEA strain, elastic modulus and FEA stress, post-gel shrinkage and FEA strain, post-gel shrinkage and FEA stress, FEA strain and cuspal deformation by strain gauge, and FEA stress and cuspal deformation by strain gauge (p<0.05). Conclusions Increasing the number of increments and high post-gel shrinkage and/or elastic modulus values caused higher stresses in the remaining tooth structure and tooth/restoration interface. Cuspal deformation measured with the strain gauge method validated the finite element analyses.

APA, Harvard, Vancouver, ISO, and other styles

14

Maekawa, Akira, Toru Oumaya, Michiyasu Noda, Shigeru Takahashi, and Toru Saito. "Residual Stress Distribution in Austenitic Stainless Steel Pipe Butt-Welded Joint Measured by Neutron Diffraction Technique." Materials Science Forum 652 (May 2010): 116–22. http://dx.doi.org/10.4028/www.scientific.net/msf.652.116.

Full text

Abstract:

This paper describes residual stress measurements and analysis of austenitic stainless steel pipe with a butt-welded joint. The measurements were done with neutron diffraction and strain gauge techniques. The measured results had typical characteristics of butt-welded pipe regarding both the decline of stress along the axial direction and the bending distribution of axial stress along the radial direction. The measured residual stress distribution by neutron diffraction was shifted more to the tensile side than that by the finite element method simulation. However, the measured radial and axial strains, except for the hoop strain determined by neutron diffraction, coincided well with analysis strains. The hoop strain was actually equivalent strain converted by a correction method because a different lattice plane had to be used to measure hoop strain. This might be one reason why the difference occurred. Therefore, future study of the correction method would be desirable.

APA, Harvard, Vancouver, ISO, and other styles

15

Du, Xiu Li, Shi Wei Hou, De Chun Lu, and Xing Lei Cheng. "Shear Band Analysis of Sand Based on Digital Image Processing Technique." Advanced Materials Research 243-249 (May 2011): 2670–78. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.2670.

Full text

Abstract:

A series of drained tests of ISO medium sand were performed to study the onset and formation of shear band. Using the digital image processing technique, the multifunctional triaxial equipment of GDS was improved. Strain isogram and local stress-strain relation at every sampling time point were recorded based on the improved equipment. The onset of shear band was from inhomogeneity of soil, while the inhomogeneous deformation can be induced by end friction and initial defect. Based on results of global stress-strain and local stress-strain relation, the end friction effect was found to have a strong influence on the radial strain. The macroscopic non-uniform sample was obtained by putting silt clay block into sand sample, evolution of shear band during the loading process showed that the discontinuation of stiffness formed at interface of two materials, with inhomogeneous deformation developing, macroscopic continues shear band fully formed.

APA, Harvard, Vancouver, ISO, and other styles

16

Hoyt, Kenneth, Flemming Forsberg, and Jonathan Ophir. "Analysis of a hybrid spectral strain estimation technique in elastography." Physics in Medicine and Biology 51, no. 2 (December 21, 2005): 197–209. http://dx.doi.org/10.1088/0031-9155/51/2/001.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Chang, WJ, and TD Brown. "Effects of Lattice Spacing on Strain Analysis using Phase Technique." Microscopy and Microanalysis 16, S2 (July 2010): 1480–81. http://dx.doi.org/10.1017/s143192761005988x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Draper, Grenville. "Geological strain analysis—a manual for the Rf/φ technique." Organic Geochemistry 9, no. 4 (January 1986): 213–14. http://dx.doi.org/10.1016/0146-6380(86)90072-0.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Boulter, C. A. "Geological strain analysis: A manual for the Rf/θ technique." Journal of Structural Geology 8, no. 6 (January 1986): 722. http://dx.doi.org/10.1016/0191-8141(86)90081-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Faisal, N. H., R. Ahmed, A. K. Prathuru, A. Paradowska, and T. L. Lee. "Measuring Residual Strain and Stress in Thermal Spray Coatings Using Neutron Diffractometers." Experimental Mechanics 62, no. 3 (November 10, 2021): 369–92. http://dx.doi.org/10.1007/s11340-021-00803-9.

Full text

Abstract:

Abstract Background During thermal spray coating, residual strain is formed within the coating and substrates due to thermo-mechanical processes and microstructural phase changes. Objective This paper provides a comprehensive guide to researchers planning to use neutron diffraction technique for thermal spray coatings, and reviews some of these studies. Methods ENGIN-X at the ISIS spallation source is a neutron diffractometer (time-of-flight) dedicated to materials science and engineering with high resolution testing. The focus is on the procedure of using ENGIN-X diffractometer for thermal spray coatings with a view that it can potentially be translated to other diffractometers. Results Number of studies involving neutron diffraction analysis in thermal spray coatings remain limited, partly due to limited number of such strain measurement facilities globally, and partly due to difficulty is applying neutron diffraction analysis to measure residual strain in the thermal spray coating microstructure. Conclusions This technique can provide a non-destructive through-thickness residual strain analysis in thermally sprayed components with a level of detail not normally achievable by other techniques. Neutron sources have been used to measure strains in thermal spray coatings, and here, we present examples where such coatings have been characterised at various neutron sources worldwide, to study residual strains and microstructures. Graphic Abstract

APA, Harvard, Vancouver, ISO, and other styles

21

Vanderby, Ray, and Sean S. Kohles. "Thermographic Stress Analysis in Cortical Bone." Journal of Biomechanical Engineering 113, no. 4 (November 1, 1991): 418–22. http://dx.doi.org/10.1115/1.2895421.

Full text

Abstract:

Under adiabatic (or near adiabatic) conditions a volumetric change in an elastic material will produce a corresponding change in temperature. Based upon this principle, thermographic stress analysis (TSA) measures changes in surface heat flux (which are related to changes in surface temperature) and relates them to a coupled form of strains or stresses. To demonstrate the feasibility of using this technique for biomechanical applications, we thermographically measured heat flux from loaded specimens of cortical bone and correlated the results with strain gage data. Regular parallelepipeds were cut from the cortex of bovine femora and loaded sinusoidally at 20 Hz. At this rate of loading, mechanically induced changes in surface temperature could be sampled (via heat flux) prior to a measureable attenuation of the thermoelastic effect. Correlation coefficients demonstrated a significant linear relationship between TSA and measured and computed mechanical parameters (stress, strain, first strain invariant, and strain energy density). TSA therefore appears to be a promising technology for experimental stress analysis in cortical bone.

APA, Harvard, Vancouver, ISO, and other styles

22

Elmahdy, Ahmed, and Patricia Verleysen. "The Use of 2D and 3D High-Speed Digital Image Correlation in Full Field Strain Measurements of Composite Materials Subjected to High Strain Rates." Proceedings 2, no. 8 (July 9, 2018): 538. http://dx.doi.org/10.3390/icem18-05439.

Full text

Abstract:

The aim of this paper is to assess and compare the performance of both high speed 2D and 3D digital image correlation (DIC) configurations in the characterization of unidirectional carbon fiber reinforced epoxy composites in high strain rate tension in the transverse direction. The criteria for assessment were in terms of strain resolution and measuring the strain localization within the gauge section. Results showed the high-speed 3D DIC technique has lower strain resolution compared to the high-speed 2D DIC technique. In addition, the analysis of the full strain fields indicated that the 3D DIC technique could accurately locate and measure the concentrations of strains within the gauge section of the tested samples.

APA, Harvard, Vancouver, ISO, and other styles

23

Mot, René De, and Jos Vanderleyden. "Application of two-dimensional protein analysis for strain fingerprinting and mutant analysis of Azospirillum species." Canadian Journal of Microbiology 35, no. 10 (October 1, 1989): 960–67. http://dx.doi.org/10.1139/m89-158.

Full text

Abstract:

Phenol-extracted total proteins from wild-type and mutant strains of Azospirillum brasilense and A. lipoferum were subjected to two-dimensional polyacrylamide gel electrophoresis. The protein patterns of both species could be readily distinguished by specific configurations of a limited number of spots. The resolving power of the technique allowed its application for strain fingerprinting. Thus, near-identity of A. brasilense strains Sp7 and Cd was demonstrated. In addition, minor changes in protein profiles resulting from spontaneous, chemically induced, or transposon-mediated mutations in the A. brasilense genome were evidenced. For a nitrate reductase negative mutant of strain Sp245 and a Sp7 mutant affected in exopolysaccharide synthesis, production of a truncated protein was involved. In Tn5-generated mutants, a gene dosage effect for the transposon-encoded neomycine phosphotransferase was observed.Key words: Azospirillum, two-dimensional protein analysis, fingerprinting.

APA, Harvard, Vancouver, ISO, and other styles

24

Taher, S. E.-D., and A. A. Almusallam. "A three-dimensional graphical method for shear strain analysis." Journal of Strain Analysis for Engineering Design 29, no. 4 (October 1, 1994): 263–66. http://dx.doi.org/10.1243/03093247v294263.

Full text

Abstract:

The efficiency of graphical methods for strain analysis depends merely on its simplicity and accuracy. For most strain definitions, the Mohr circle has proved to be the most powerful graphical technique. Unfortunately, its three-dimensional form has limitations concerning the determination of the shearing strain components on a general oblique plane. In this paper, the various deformation quantifiers and the existing extensions to Mohr's method which account for its drawbacks are briefly reviewed. A novel proposal to be appended to Mohr's original construction, allowing its complete generality, is given. It has the form of a simplified complementary triangular construction. A mathematical formulation of the suggested graphical techniques on the basis of Cauchy's formula and vector analysis is carried out.

APA, Harvard, Vancouver, ISO, and other styles

25

Deng, Wen Jun, Ping Lin, Zi Chun Xie, and Qing Li. "Analysis of Large-Strain Extrusion Machining with Different Chip Compression Ratios." Journal of Nanomaterials 2012 (2012): 1–12. http://dx.doi.org/10.1155/2012/851753.

Full text

Abstract:

Large-Strain Extrusion Machining (LSEM) is a novel-introduced process for deforming materials to very high plastic strains to produce ultra-fine nanostructured materials. Before the technique can be exploited, it is important to understand the deformation behavior of the workpiece and its relationship to the machining parameters and friction conditions. This paper reports finite-element method (FEM) analysis of the LSEM process to understand the evolution of temperature field, effective strain, and strain rate under different chip compression ratios. The cutting and thrust forces are also analyzed with respect to time. The results show that LSEM can produce very high strains by changing in the value of chip compression ratio, thereby enabling the production of nanostructured materials. The shape of the chip produced by LSEM can also be geometrically well constrained.

APA, Harvard, Vancouver, ISO, and other styles

26

Iyengar, Sampath S., and Simona Percec. "Rietveld analysis of high-density polyethylene." Powder Diffraction 9, no. 3 (September 1994): 217–20. http://dx.doi.org/10.1017/s0885715600019266.

Full text

Abstract:

Wide angle X-ray powder diffraction data from unoriented and uniaxially oriented films of high-density polyethylene were analyzed by the Rietveld whole pattern profile fitting technique. A Voigt function was used to model the profile and extract crystallographic information such as the unit cell dimensions, crystallite size and strain, and degree of orientation. The analysis revealed that the technique was efficient in providing not only accurate unit cell dimensions without an internal standard, but also crystallite size and strain information. The oriented films were also successfully modeled with this technique.

APA, Harvard, Vancouver, ISO, and other styles

27

Veress, Alexander I., Gregory Klein, and Grant T. Gullberg. "A Comparison of Hyperelastic Warping of PET Images with Tagged MRI for the Analysis of Cardiac Deformation." International Journal of Biomedical Imaging 2013 (2013): 1–14. http://dx.doi.org/10.1155/2013/728624.

Full text

Abstract:

The objectives of the following research were to evaluate the utility of a deformable image registration technique known as hyperelastic warping for the measurement of local strains in the left ventricle through the analysis of clinical, gated PET image datasets. Two normal human male subjects were sequentially imaged with PET and tagged MRI imaging. Strain predictions were made for systolic contraction using warping analyses of the PET images and HARP based strain analyses of the MRI images. Coefficient of determinationR2values were computed for the comparison of circumferential and radial strain predictions produced by each methodology. There was good correspondence between the methodologies, withR2values of 0.78 for the radial strains of both hearts and from anR2=0.81andR2=0.83for the circumferential strains. The strain predictions were not statistically different(P≤0.01). A series of sensitivity results indicated that the methodology was relatively insensitive to alterations in image intensity, random image noise, and alterations in fiber structure. This study demonstrated that warping was able to provide strain predictions of systolic contraction of the LV consistent with those provided by tagged MRI Warping.

APA, Harvard, Vancouver, ISO, and other styles

28

Babu, S., and P. K. Iyer. "Inelastic Analysis of Components Using a Modulus Adjustment Scheme." Journal of Pressure Vessel Technology 120, no. 1 (February 1, 1998): 1–5. http://dx.doi.org/10.1115/1.2841879.

Full text

Abstract:

Mechanical components and structures loaded into inelastic region can fail by low cycle fatigue (LCF). Evaluation of inelastic strain is an important stage in the LCF life prediction methodology. Different techniques, viz., experimental methods, elastic-plastic finite element analysis (FEA), and robust methods, can be used to predict inelastic strains. The state predicted by available robust methods does not correspond to equilibrium state of the component. A method called MARS (modulus adjustment and redistribution of stress) based on linear elastic FEA has been developed to obtain equilibrium and kinematic distributions close to the actual one. The proposed method uses an iterative strategy combined with a modulus reduction technique.

APA, Harvard, Vancouver, ISO, and other styles

29

Blanc-Potard, Anne-Beatrice, Colin Tinsley, Isabel Scaletsky, Chantal Le Bouguenec, Julie Guignot, Alain L. Servin, Xavier Nassif, and Marie-Francoise Bernet-Camard. "Representational Difference Analysis between Afa/Dr Diffusely Adhering Escherichia coli and Nonpathogenic E. coli K-12." Infection and Immunity 70, no. 10 (October 2002): 5503–11. http://dx.doi.org/10.1128/iai.70.10.5503-5511.2002.

Full text

Abstract:

ABSTRACT Diffusely adhering Escherichia coli strains harboring Afa/Dr adhesins (Afa/Dr DAEC) have been associated with diarrhea and urinary tract infections (UTIs). The present work is the first extensive molecular study of a Afa/Dr DAEC strain using the representational difference analysis technique. We have searched for DNA sequences present in strain C1845, recovered from a diarrheagenic child, but absent from a nonpathogenic K-12 strain. Strain C1845 harbors part of a pathogenicity island (PAICFT073) and several iron transport systems found in other E. coli pathovars. We did not find genes encoding factors known to subvert host cell proteins, such as type III secretion system or effector proteins. Several C1845-specific sequences are homologous to putative virulence genes or show no homology with known sequences, and we have analyzed their distribution among Afa/Dr and non-Afa/Dr clinical isolates and among strains from the E. coli Reference Collection. Three C1845-specific sequences (MO30, S109, and S111) have a high prevalence (77 to 80%) among Afa/Dr strains and a low prevalence (12 to 23%) among non-Afa/Dr strains. In addition, our results indicate that strain IH11128, an Afa/Dr DAEC strain recovered from a patient with a UTI, is genetically closely related to strain C1845.

APA, Harvard, Vancouver, ISO, and other styles

30

Wright, Stuart I., Matthew M. Nowell, and David P. Field. "A Review of Strain Analysis Using Electron Backscatter Diffraction." Microscopy and Microanalysis 17, no. 3 (March 22, 2011): 316–29. http://dx.doi.org/10.1017/s1431927611000055.

Full text

Abstract:

AbstractSince the automation of the electron backscatter diffraction (EBSD) technique, EBSD systems have become commonplace in microscopy facilities within materials science and geology research laboratories around the world. The acceptance of the technique is primarily due to the capability of EBSD to aid the research scientist in understanding the crystallographic aspects of microstructure. There has been considerable interest in using EBSD to quantify strain at the submicron scale. To apply EBSD to the characterization of strain, it is important to understand what is practically possible and the underlying assumptions and limitations. This work reviews the current state of technology in terms of strain analysis using EBSD. First, the effects of both elastic and plastic strain on individual EBSD patterns will be considered. Second, the use of EBSD maps for characterizing plastic strain will be explored. Both the potential of the technique and its limitations will be discussed along with the sensitivity of various calculation and mapping parameters.

APA, Harvard, Vancouver, ISO, and other styles

31

Mayo, Unai, Nerea Isasti, José M. Rodríguez-Ibabe, and Pello Uranga. "Analysis of Strain Partitioning in Intercritically Deformed Microstructures via Interrupted Tensile Tests." Metals 11, no. 1 (January 8, 2021): 112. http://dx.doi.org/10.3390/met11010112.

Full text

Abstract:

Intercritically deformed steels present combinations of different types of ferrite, such as deformed ferrite (DF) and non-deformed ferrite (NDF) grains, which are transformed during the final deformation passes and final cooling step. Recently, a grain identification and correlation technique based on EBSD has been employed together with a discretization methodology, enabling a distinction to be drawn between different ferrite populations (NDF and DF grains). This paper presents a combination of interrupted tensile tests with crystallographic characterization performed by means of Electron Backscatter Diffraction (EBSD), by analyzing the evolution of an intercritically deformed micro-alloyed steel. In addition to this, and using the nanoindentation technique, both ferrite families were characterized micromechanically and the nanohardness was quantified for each population. NDF grains are softer than DF ones, which is related to the presence of a lower fraction of low-angle grain boundaries. The interrupted tensile tests show the different behavior of low- and high-angle grain boundary evolution as well as the strain partitioning in each ferrite family. NDF population accommodates most of the deformation at initial strain intervals, since strain reaches 10%. For higher strains, NDF and DF grains behave similarly to the strain applied.

APA, Harvard, Vancouver, ISO, and other styles

32

Mayo, Unai, Nerea Isasti, José M. Rodríguez-Ibabe, and Pello Uranga. "Analysis of Strain Partitioning in Intercritically Deformed Microstructures via Interrupted Tensile Tests." Metals 11, no. 1 (January 8, 2021): 112. http://dx.doi.org/10.3390/met11010112.

Full text

Abstract:

Intercritically deformed steels present combinations of different types of ferrite, such as deformed ferrite (DF) and non-deformed ferrite (NDF) grains, which are transformed during the final deformation passes and final cooling step. Recently, a grain identification and correlation technique based on EBSD has been employed together with a discretization methodology, enabling a distinction to be drawn between different ferrite populations (NDF and DF grains). This paper presents a combination of interrupted tensile tests with crystallographic characterization performed by means of Electron Backscatter Diffraction (EBSD), by analyzing the evolution of an intercritically deformed micro-alloyed steel. In addition to this, and using the nanoindentation technique, both ferrite families were characterized micromechanically and the nanohardness was quantified for each population. NDF grains are softer than DF ones, which is related to the presence of a lower fraction of low-angle grain boundaries. The interrupted tensile tests show the different behavior of low- and high-angle grain boundary evolution as well as the strain partitioning in each ferrite family. NDF population accommodates most of the deformation at initial strain intervals, since strain reaches 10%. For higher strains, NDF and DF grains behave similarly to the strain applied.

APA, Harvard, Vancouver, ISO, and other styles

33

Ezeilo, A. N., and G. A. Webster. "Neutron diffraction analysis of the residual stress distribution in a bent bar." Journal of Strain Analysis for Engineering Design 35, no. 4 (May 1, 2000): 235–46. http://dx.doi.org/10.1243/0309324001514387.

Full text

Abstract:

A well-characterized residual stress distribution resulting from four-point bending has been analysed using the neutron diffraction technique. Residual stresses were obtained from the strains measured at discrete positions through the bent bar on the (111) and (311) crystal planes of a nickel-based alloy using the appropriate diffraction elastic constants. In addition a profile refinement method was used to determine the residual stresses from average strains from all the diffraction peaks in the spectrum. The measured residual stress profiles have also been compared with strain gauge data and with analytical and finite element predictions. It has been established that the profile refinement approach gives stresses which most closely match those obtained by the non-diffraction techniques.

APA, Harvard, Vancouver, ISO, and other styles

34

Whan, Gabrielle, R. John Runciman, and Mark Hurtig. "Determining Effective Centroid Position in Biomechanical Testing: A Technique for Simplifying Whole Bone Analysis." Journal of Biomechanical Engineering 127, no. 5 (May 4, 2005): 736–41. http://dx.doi.org/10.1115/1.1993663.

Full text

Abstract:

Background: Whole bone in vitro biomechanical compressive testing can be complicated by three factors: sample asymmetry, heterogeneous material properties, and unknown effective centroid location. Method of approach: The technique presented here facilitates the calculation of effective centroid position, modulus of elasticity and equivalent uniform strain magnitude for a cross section of bone from a simple whole bone compressive test. Simplification of section response to load is achieved through a combination of linear beam and simple planer geometry theory. The technique requires three longitudinal strain gauges be affixed around the test specimen cross section of interest, gauge position need not be determined. Sample loading is then accomplished using a simple four point loading jig. Results: Results of the technique are presented on an object with known elasticity and geometry, an aluminium tube, and seven pairs of equine third metacarpal whole bones. Conclusions: Average cross section modulus of elasticity, equivalent uniform cross section strain, and effective centroid locations were all predicted to within the range of published values. Employing the testing setup and analysis technique presented in this paper resulted in a significant savings in both implementation complexity and cost over previously available techniques.

APA, Harvard, Vancouver, ISO, and other styles

35

Brickner, Jason H., Timothy J. Lynch, Dawn Zeilinger, and Eduardo Orias. "Identification, Mapping and Linkage Analysis of Randomly Amplified DNA Polymorphisms in Tetrahymena thermophila." Genetics 143, no. 2 (June 1, 1996): 811–21. http://dx.doi.org/10.1093/genetics/143.2.811.

Full text

Abstract:

Abstract Using the random amplified polymorphic DNA (RAPD) technique and exploiting the unique genetics of Tetrahymena themnophila, we have identified and characterized 40 DNA polymorphisms occurring between two inbred strains (B and C3) of this ciliated protozoan. These RAPD markers permit the PCR amplification of a DNA species using template DNA from SB1969 (B strain) but fail to do so using DNA from C3-368-5 (C3 strain). Polymorphisms were mapped to chromosomes using a panel of monosomic strains constructed by crossing B strainderived nullisomic strains to inbred strain C3. They map to all five chromosomes and appear to be evenly distributed throughout the genome. Chromosomal groups were then analyzed for linkage using meiotic segregants; four linkage groups were identified in chromosomes IR, 2L, 3 and 5. The RAPD method appears useful for the construction of a genetic map of the Tetrahymena genome based on DNA polymorphisms.

APA, Harvard, Vancouver, ISO, and other styles

36

Liu, Ling, Nagahisa Ogasawara, Norimasa Chiba, and Xi Chen. "Can indentation technique measure unique elastoplastic properties?" Journal of Materials Research 24, no. 3 (March 2009): 784–800. http://dx.doi.org/10.1557/jmr.2009.0100.

Full text

Abstract:

Indentation is widely used to extract material elastoplastic properties from measured force-displacement curves. Many previous studies argued or implied that such a measurement is unique and the whole material stress-strain curve can be measured. Here we show that first, for a given indenter geometry, the indentation test cannot effectively probe material plastic behavior beyond a critical strain, and thus the solution of the reverse analysis of the indentation force-displacement curve is nonunique beyond such a critical strain. Secondly, even within the critical strain, pairs of mystical materials can exist that have essentially identical indentation responses (with differences below the resolution of published indentation techniques) even when the indenter angle is varied over a large range. Thus, fundamental elastoplastic behaviors, such as the yield stress and work hardening properties (functions), cannot be uniquely determined from the force-displacement curves of indentation analyses (including both plural sharp indentation and deep spherical indentation). Explicit algorithms of deriving the mystical materials are established, and we qualitatively correlate the sharp and spherical indentation analyses through the use of critical strain. The theoretical study in this paper addresses important questions of the application range, limitations, and uniqueness of the indentation test, as well as providing useful guidelines to properly use the indentation technique to measure material constitutive properties.

APA, Harvard, Vancouver, ISO, and other styles

37

Iguchi, Shin-ichi, Kensuke Kubo, Seiichi Yamane, and Hiroaki Igarashi. "Study on Strain Calculational Technique of Concrete Bridges by Frame Analysis." IABSE Symposium Report 96, no. 5 (January 1, 2009): 146–55. http://dx.doi.org/10.2749/222137809796088413.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Ward, M. B., R. Brydson, A. P. Brown, and R. F. Cochrane. "Analysis of strain in manganese nanoparticles using the optical moiré technique." Journal of Physics: Conference Series 126 (August 1, 2008): 012068. http://dx.doi.org/10.1088/1742-6596/126/1/012068.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

ODA, Juhachi, and Makoto HATTORI. "Inverse Analysis Technique to Obtain Contact Stress Distributions Using Strain Datum." Transactions of the Japan Society of Mechanical Engineers Series A 58, no. 545 (1992): 106–11. http://dx.doi.org/10.1299/kikaia.58.106.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

ODA, Juhachi, and Makoto HATTORI. "An Inverse Analysis Technique to Obtain Material Properties Using Strain Data." Transactions of the Japan Society of Mechanical Engineers Series A 58, no. 552 (1992): 1376–81. http://dx.doi.org/10.1299/kikaia.58.1376.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Badadani, Vijayakumar, T. S. Sriranga, and Shivashankar R. Srivatsa. "Analysis of Uncertainty in Digital Image Correlation Technique for Strain Measurement." Materials Today: Proceedings 5, no. 10 (2018): 20912–19. http://dx.doi.org/10.1016/j.matpr.2018.06.479.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Hillery, M. T., and S. Griffin. "An embedded-strain-gauge technique of stress analysis in rod drawing." Journal of Materials Processing Technology 47, no. 1-2 (December 1994): 1–12. http://dx.doi.org/10.1016/0924-0136(94)90081-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Cardoso, Kelen Cristiane, Jonathan Gazzola, and Inacio Maria Dal Fabbro. "Application of moiré technique on strain analysis in farm machinery elements." Revista Ciência Agronômica 45, no. 3 (September 2014): 479–87. http://dx.doi.org/10.1590/s1806-66902014000300007.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Choi, Ji Young, Costi D. Sifri, Boyan C. Goumnerov, Laurence G. Rahme, Frederick M. Ausubel, and Stephen B. Calderwood. "Identification of Virulence Genes in a Pathogenic Strain of Pseudomonas aeruginosa by Representational Difference Analysis." Journal of Bacteriology 184, no. 4 (February 15, 2002): 952–61. http://dx.doi.org/10.1128/jb.184.4.952-961.2002.

Full text

Abstract:

ABSTRACT Pseudomonas aeruginosa is an opportunistic pathogen that may cause severe infections in humans and other vertebrates. In addition, a human clinical isolate of P. aeruginosa, strain PA14, also causes disease in a variety of nonvertebrate hosts, including plants, Caenorhabditis elegans, and the greater wax moth, Galleria mellonella. This has led to the development of a multihost pathogenesis system in which plants, nematodes, and insects have been used as adjuncts to animal models for the identification of P. aeruginosa virulence factors. Another approach to identifying virulence genes in bacteria is to take advantage of the natural differences in pathogenicity between isolates of the same species and to use a subtractive hybridization technique to recover relevant genomic differences. The sequenced strain of P. aeruginosa, strain PAO1, has substantial differences in virulence from strain PA14 in several of the multihost models of pathogenicity, and we have utilized the technique of representational difference analysis (RDA) to directly identify genomic differences between P. aeruginosa strains PA14 and PAO1. We have found that the pilC, pilA, and uvrD genes in strain PA14 differ substantially from their counterparts in strain PAO1. In addition, we have recovered a gene homologous to the ybtQ gene from Yersinia, which is specifically present in strain PA14 but absent in strain PAO1. Mutation of the ybtQ homolog in P. aeruginosa strain PA14 significantly attenuates the virulence of this strain in both G. mellonella and a burned mouse model of sepsis to levels comparable to those seen with PAO1. This suggests that the increased virulence of P. aeruginosa strain PA14 compared to PAO1 may relate to specific genomic differences identifiable by RDA.

APA, Harvard, Vancouver, ISO, and other styles

45

Economikos, L. "Imaging of photo-occlusion colour films for quantitative strain and stress analysis." Journal of Strain Analysis for Engineering Design 24, no. 1 (January 1, 1989): 1–5. http://dx.doi.org/10.1243/03093247v241001.

Full text

Abstract:

Digital image analysis and processing techniques have been applied to colour films obtained by a photo-occlusion method to quantitatively describe strain and stress distributions. The objective here is to outline the different colour areas (training areas) on each image accurately and consistently in order for a quantitative comparison of the induced stress on each film to be made based on the size of each colour area. To ensure that the outlined colour areas are uniform in terms of grey levels (isochromatic areas), a statistical analysis was pursued. To ensure consistency of the outline process on each image, an autocorrelation distance was used. The technique described allows direct quantitative judgement of strain fields obtained ‘before’ and ‘after’ treatment. The technique can be applied in any research area where a sequence of isochromatic areas can be recorded on a photographic film.

APA, Harvard, Vancouver, ISO, and other styles

46

SHIMANA, Takatsugu, Katsuya TSUJINAKA, and Yoshinobu WATANABE. "A11 Establishment of polygon strain analysis technique on 3D-CG and application to skin strain simulation." Proceedings of Joint Symposium: Symposium on Sports Engineering, Symposium on Human Dynamics 2006 (2006): 60–63. http://dx.doi.org/10.1299/jsmesports.2006.0_60.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Noyan, I. C., and G. Sheikh. "X-ray tensile testing of thin films." Journal of Materials Research 8, no. 4 (April 1993): 764–70. http://dx.doi.org/10.1557/jmr.1993.0764.

Full text

Abstract:

The “x-ray tensile test” is the combination of the standard uniaxial tensile test with x-ray diffraction techniques. In this test, in addition to the mechanical stress-strain values usually obtained from a tensile test, one measures the x-ray strain and stress in the diffracting regions of the sample. In multilayer thin films or in multiphase materials, x-ray diffraction enables the determination of strains and stresses in the individual layers or phases. Correlation of the x-ray data with the mechanical stress-strain values may be used to analyze strain and load partitioning within the specimen. In this paper an extended theoretical analysis of this technique and its application to evaporated Cu films on Ni substrates is presented.

APA, Harvard, Vancouver, ISO, and other styles

48

Martin, Hagara, and Pástor Miroslav. "A Complex Review of the Possibilities of Residual Stress Analysis Using Moving 2D and 3D Digital Image Correlation System." Strojnícky časopis - Journal of Mechanical Engineering 71, no. 1 (September 1, 2021): 61–78. http://dx.doi.org/10.2478/scjme-2021-0006.

Full text

Abstract:

Abstract Understanding the levels of residual stresses in the material is very important in predicting the service life of structural elements. One of the most widely used techniques to quantify them is the drilling method, where a small hole is milled in the structure. If the residual stresses are present, stress redistribution will occur, resulting in deformation of the hole surroundings. Nowadays, there is an effort to replace the conventionally used strain gauges, i.e. special strain gauge rosettes, with full-field optical experimental techniques. This paper deals with analysing the possibilities of measuring the relieved strains/stresses with a unique drilling/measuring device, which, unlike other non-commercial measuring systems, uses the moving digital image correlation (DIC) system. Since correlation systems do not tend to move during operation, an analysis was performed describing the effect of changing the position of the single and stereo camera correlation systems on the quality of the results of the strain/stress analysis performed in the vicinity of the milled hole. The conclusion from the analyses performed is that there is no significant accumulation of correlation errors during measurement. Therefore, the information on the magnitudes of the strains/stresses relieved obtained by the moving DIC system can be used to quantify the residual stresses with an expected error corresponding to the sensitivity of this full-field optical experimental technique.

APA, Harvard, Vancouver, ISO, and other styles

49

Ogasawara, Nagahisa, Norimasa Chiba, and Xi Chen. "Representative Strain of Indentation Analysis." Journal of Materials Research 20, no. 8 (August 1, 2005): 2225–34. http://dx.doi.org/10.1557/jmr.2005.0280.

Full text

Abstract:

Indentation analysis based on the concept of representative strain offers an effective way of obtaining mechanical properties, especially work-hardening behavior of metals, from reverse analysis of indentation load–displacement data, and does not require measuring of the projected contact area. The definition of representative strain adopted in previous studies [e.g., Dao et al., Acta Mater.49, 3899 (2001)] has a weak physical basis, and it works only for a limited range in some sense of engineering materials. A new indentation stress-state based formulation of representation is proposed in this study, which is defined as the plastic strain during equi-biaxial loading. Extensive numerical analysis based on the finite element method has shown that with the new formulation of representative strain and representative stress, the critical normalized relationship between load and material parameters is essentially independent of the work-hardening exponent for all engineering materials, and the results also hold for three distinct indenter angles. The new technique is used for four materials with mechanical properties outside the applicable regime of previous studies, and the reverse analysis has validated the present analysis. The new formulation based on indentation stress-state based definition of representative strain has the potential to quickly and effectively measure the mechanical properties of essentially all engineering materials as long as their constitutive behavior can be approximated into a power-law form.

APA, Harvard, Vancouver, ISO, and other styles

50

Huntley, J. M. "Automated fringe pattern analysis in experimental mechanics: A review." Journal of Strain Analysis for Engineering Design 33, no. 2 (February 1, 1998): 105–25. http://dx.doi.org/10.1243/0309324981512850.

Full text

Abstract:

The paper reviews the main numerical techniques that have been developed to carry out fully automated analysis of fringe patterns resulting from solid mechanics experiments. These include temporal and spatial phase shifting interferometry, temporal and spatial phase unwrapping, and calculation of strain fields from the phase maps. Systematic and random errors associated with the various procedures are also analysed. A unified treatment for both speckle and smooth-wavefront interferograms is presented, and the common features underlying many of the algorithms are emphasized. The paper is illustrated with applications that include ball impact (moiré photography), bending waves in orthotropic plates (double-pulsed dual-reference wave holography) and finite strains in propellant grains (fine grid technique).

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Strain analysis technique'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles