Shearography – In identifying the presence and subsequent measurement of residual stresses

Abstract

Residual stresses are known to influence the performance of components in structures usually in a detrimental/damaging manner, however sometimes their presence can be advantageous, especially if they are compressive, thus inhibiting fatigue failure. It is recognized that residual stresses are induced during manufacturing processes and as such they are uncontrolled and unknown. This paper deals with the feasibility study of using Digital Shearography to identify the presence of Residual Stresses and subsequently quantify them. Experiments were performed on mild steel rectangular bars where a compressive residual stress was introduced in one of the surfaces of the specimens. The results are encouraging in that Digital Shearography could be developed as a residual stress measuring tool thus prompting further parametric studies. The testing method also appears to yield the value of the Young’s modulus of the material.