Dynamic ESPI System for Spatio-Temporal Strain Analysis of a Deforming Solid Object

2006 ◽  
Vol 326-328 ◽  
pp. 95-98 ◽  
Author(s):  
Tomohisa Shiraishi ◽  
Satoru Toyooka ◽  
Hirofumi Kadono ◽  
Takayuki Saito ◽  
Sun Ping
Keyword(s):  
Speckle Pattern ◽  
Plane Deformation ◽  
Strain Analysis ◽  
Electronic Speckle Pattern Interferometry ◽  
Deformation Analysis ◽  
Al Alloy ◽  
Alloy Sample ◽  
Speckle Patterns ◽  
Stress Curve ◽  
Spatio Temporal

In Dynamic Electronic Speckle Pattern Interferometry (DESPI), deformation analysis could be done for successively acquired frame data of interfering speckle patterns with no additional frames like phase shifting speckle patterns. Our final goal is to obtain a temporally varying process of two-dimensional strain field. Two normal strains and shearing strain are derived by numerical derivatives of two components of in-plane deformation. Analyzed results of tensile experiments of an Al-alloy sample will be shown. In the experiments, propagation of a strain localization band accompanied by serration of a stress curve was clearly observed quantitatively analyzed.

Thermal strain analysis of composite materials by electronic speckle pattern interferometry

2000 ◽  
Vol 14 (5) ◽  
pp. 477-482 ◽  
Author(s):  
Koung Suk Kim ◽  
Wan Shik Jang ◽  
Myung Seak Hong ◽  
Ki Soo Kang ◽  
Hyun Chul Jung ◽  
...  
Keyword(s):  
Composite Materials ◽  
Speckle Pattern ◽  
Thermal Strain ◽  
Strain Analysis ◽  
Electronic Speckle Pattern Interferometry

Measurement of Leadframe Strain in Electrically Active Power Semiconductors

2015 ◽  
Author(s):  
Seth M. Avery ◽  
Robert D. Lorenz
Keyword(s):  
Significant Contribution ◽  
Speckle Pattern ◽  
Surface Displacement ◽  
Experimental Methodology ◽  
Electronic Speckle Pattern Interferometry ◽  
Power Semiconductors ◽  
Active Devices ◽  
Speckle Patterns ◽  
Noise Measurements ◽  
Strain Model

In this work, thermal-mechanical leadframe strain in an electrically active IGBT was measured using electronic speckle pattern interferometry (ESPI). ESPI is a non-contact optical technique capable of high resolution surface displacement measurements. The significant contribution of this paper is an experimental methodology by which strain can be measured in electrically active devices. A 3-D ESPI test stand was developed, combining two cameras to simultaneously capture the local (interconnect level) and global (device level) displacements. Through the combination of incremental sub-loads and mathematical recorrelation of speckle patterns, device power loads have been measured (which would have been otherwise impossible due to speckle decorrelation, which limits measurement of large deformations). A model-based tracking technique was developed from coupled experimental noise measurements and FE modeling — allowing for optimal strain solution to be extracted from noisy displacement results. The developed and experimentally-validated thermal-mechanical FE strain model agreed to within 7% of ESPI strain measurements.

Stress Measurements in Glass and Plastic by Optical Hole-Drilling

2013 ◽  
Vol 768-769 ◽  
pp. 95-100
Author(s):  
Markus Laakkonen ◽  
Theo J. Rickert ◽  
Lasse Suominen
Keyword(s):  
Depth Profile ◽  
Speckle Pattern ◽  
Electronic Speckle Pattern Interferometry ◽  
Hole Drilling ◽  
Stress Profile ◽  
Bending Stress ◽  
Toughened Glass ◽  
Compressive Stresses ◽  
Stress Curve ◽  
Metallic Parts

Quantitative residual stress depth profile measurements are common in metallic parts but not in glass or plastic. This paper describes some experimental stress depth profile measurements using hole-drilling with electronic speckle pattern interferometry (ESPI) in two types of glasses and two thermoplastics. Stress depth profiles in laminated and toughened glass specimens show the expected low stresses in the former and significant compressive stresses near the surface in the latter for the as-is condition. The stress curves shift towards tensile stresses during slight bending deformation, as expected. The bending devices initially used for experiments with Bayblend® and Makrolon® were deforming the specimens too severely to allow proper, static, measurements. Significant stress reductions due to creep were measured for extended bending times. Subsequent measurements for less severe bending show similar stress curve characteristics. Residual stresses in the as-is condition apparently account for some of the differences to the predicted bending stress profile.

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