Stress Analysis by Thermoelastic Techniques

Failures in structures often develop from small cracks which form initially at stress concentration points such as a structural discontinuity or the welding toe of a component. Though strain gauge instrumentation can usually be applied to the stress measurement at such points, this method requires fairly complicated procedures and considerable preparation time. Recent advances in infrared technology have allowed the development of highly sensitive noncontacting instruments, for instance using thermoelastic stress analysis. This paper presents the results of some basic experiments on stress measurement using thermoelastic stress analysis. The system produces stress maps which indicate the stress concentration around notches in testspecimens and bracket ends in structural models. The experimental maps show good agreement with the results from finite element methods or strain gauge measurements.