Characterization of Strain Fields Around Weld Defects

1987 ◽  
Vol 109 (3) ◽  
pp. 226-229
Author(s):  
S. A. Chavez ◽  
V. A. Deason
Keyword(s):  
Surface Defect ◽  
Local Strain ◽  
Moiré Interferometry ◽  
Moire Interferometry ◽  
Strain Gages ◽  
Strain Fields ◽  
Full Field ◽  
Strain Data ◽  
Set Up

Moire interferometry is used as an alternate technique to resistance strain gages in finding full-field, local strain response of weldments to applied loads. The principles of moire interferometry and the experimental set-up are explained. Data from the two techniques are compared, with no major discrepancies. The strain field around a surface defect is analyzed using moire data. It is concluded that the moire technique is useful for obtaining full-field strain data in welds.

Local strain and defects in silicon wafers due to nanoindentation revealed by full-field X-ray microdiffraction imaging

2015 ◽  
Vol 22 (4) ◽  
pp. 1083-1090 ◽  
Author(s):  
Z. J. Li ◽  
A. N. Danilewsky ◽  
L. Helfen ◽  
P. Mikulik ◽  
D. Haenschke ◽  
...  
Keyword(s):  
Local Strain ◽  
Strain Engineering ◽  
Silicon Wafers ◽  
Defect Characterization ◽  
Quantitative Characterization ◽  
Strain Fields ◽  
Full Field ◽  
X Ray ◽  
Quantitative Mapping

Quantitative characterization of local strain in silicon wafers is critical in view of issues such as wafer handling during manufacturing and strain engineering. In this work, full-field X-ray microdiffraction imaging using synchrotron radiation is employed to investigate the long-range distribution of strain fields in silicon wafers induced by indents under different conditions in order to simulate wafer fabrication damage. The technique provides a detailed quantitative mapping of strain and defect characterization at the micrometer spatial resolution and holds some advantages over conventional methods.

Experimental Characterization of Mechanical Behavior of Cord-Rubber Composites

1982 ◽  
Vol 10 (1) ◽  
pp. 37-54 ◽  
Author(s):  
M. Kumar ◽  
C. W. Bert
Keyword(s):  
Response Characteristic ◽  
Cord Compression ◽  
Complete Characterization ◽  
Strain Response ◽  
Strain Gages ◽  
Experimental Characterization ◽  
Rubber Composites ◽  
Stress Strain ◽  
Strain Data

Abstract Unidirectional cord-rubber specimens in the form of tensile coupons and sandwich beams were used. Using specimens with the cords oriented at 0°, 45°, and 90° to the loading direction and appropriate data reduction, we were able to obtain complete characterization for the in-plane stress-strain response of single-ply, unidirectional cord-rubber composites. All strains were measured by means of liquid mercury strain gages, for which the nonlinear strain response characteristic was obtained by calibration. Stress-strain data were obtained for the cases of both cord tension and cord compression. Materials investigated were aramid-rubber, polyester-rubber, and steel-rubber.

Transmission Microscopic Moire´ Interferometry for Nanoscale Deformation Measurements

2003 ◽  
Author(s):  
C. W. Han ◽  
S. Cho ◽  
B. Han
Keyword(s):  
Spatial Resolution ◽  
Optical Method ◽  
Moiré Interferometry ◽  
Field Of View ◽  
Moire Interferometry ◽  
Small Field ◽  
Accurate Analysis ◽  
Full Field ◽  
Deformation Measurements ◽  
Small Field Of View

Moire´ interferometry is a full-field optical method that has high displacement, strain and spatial resolution. The method has been used extensively for deformation analyses in the various fields of mechanics. Special considerations arise when deformation measurements of tiny specimens or tiny regions of larger specimens are sought. The relative displacements within a small field of view will be small (even if the strains are not small), so the number of morie´ fringes might not be enough for an accurate analysis.

Full Field Joule Heating Measurement of Copper Plate Using Phase Shifting Moire´ Interferometry in Microscopic Scale

2009 ◽  
Author(s):  
Bicheng Chen ◽  
Cemal Basaran
Keyword(s):  
Joule Heating ◽  
Current Density ◽  
Moiré Interferometry ◽  
Phase Shifting ◽  
Moire Interferometry ◽  
Heating Effect ◽  
Full Field ◽  
Microscopic Scale ◽  
Joule Heating Effect ◽  
Heating Effects

Heat generated from Joule heating is an important factor in several failure mechanisms in microelectronic packaging (e.g. thermomigration, electromigration and etc) and large amount of the heat causes severe heat dissipation problem. It is further exaggerated by the continuous marching towards miniaturization of microelectronics. The techniques of measuring the Joule heating effects at the microscopic scale are quite limited especially for the full field measurement. Infrared microscopic imaging has been reported to measure the heat radiation by the Joule heating in the microscopic scale. Moire´ interferometry with phase shifting is a highly sensitive and a high resolution method to measure the in-plane full field strain. In this paper, it is demonstrated that the Joule heating effect can be measured by Moire´ interferometry with phase shifting at the microscopic scale. The copper sheet is used for the demonstration because of isotropic material property and well known thermal properties and parameters. The specimen was designed to minimize the out-of-plane strain and the strain caused by the thermal-structural effects. A finite element model was developed to verify the design of the structure of the specimen and the specimen was tested under different current density (input current from 0 to 24 A). Based on the research, a correlation relationship between the current density and the strain in two orthogonal directions (one in the direction of the current flow) was determined. The regression coefficients of the full field were analyzed. The experiment demonstrates the capability of measuring microscopic Joule heating effects by using Moire´ interferometry with phase shifting. The method can be further applied to the measurement of Joule heating effect in the microscopic solid structures in the electronic packaging devices.

Residual Stress Measurement in Spot Welds and the Effect of Fatigue Loading on Redistribution of Stresses Using High Sensitivity Moire´ Interferometry

2000 ◽  
Vol 123 (1) ◽  
pp. 132-138 ◽  
Author(s):  
Sanjeev K. Khanna ◽  
Canlong He ◽  
Hari N. Agrawal
Keyword(s):  
Residual Stress ◽  
Stress Measurement ◽  
Low Cycle Fatigue ◽  
High Sensitivity ◽  
Fatigue Loading ◽  
Moiré Interferometry ◽  
Spot Weld ◽  
Moire Interferometry ◽  
Spot Welds ◽  
Full Field

Residual stress distribution has been determined in spot welds, which are generally used to join mild steel sheets. Various spot weld configurations were investigated using the full-field, experimental, optical technique of high sensitivity moire´ interferometry. These stresses were found to be in the range 250–300 MPa (tensile) in the center and decreased to 40–100 MPa (tensile) at the edge of the weld nugget. Low cycle fatigue loading of the spot weld caused the residual stress to drop in the weld center by about 30 percent and increase at the edges by as much as 100 percent.

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