EVALUATION OF STRESS-FIELD PARAMETERS IN FRACTURE-MECHANICS BY PHOTOELASTICITY - REVISITED

Multi-parameter stress field equations have been reported in the past two decades to model the elastic stress field in the neighbourhood of a crack lying in finite bodies. Notably among them are the generalised Westergaard equations proposed by Sanford, Williams' eigen function e xpansion and the recent one of Atluri and Kobayashi. The equivalence a mong these equations is brought out. Using the equations of Atluri and Kobayashi an over-deterministic least squares technique is proposed t o evaluate the mixed-mode stress field parameters by the technique of photoelasticity. It is shown that the use of Atluri and Kobayashi's eq uations leads to a very simple software where one can independently in crease the number of terms in Mode I or Mode II series depending on th e specific problem requirement until the experimental fringes are corr ectly modelled. The software is validated by solving three example pro blems. The example problems emphasise that the use of multi-parameter stress field equations is not just an academic curiosity but a practic al necessity to apply concepts of Fracture Mechanics to solve real lif e problems. Further, it is shown that the multi-parameter solution all ows the collection of data from a larger zone which helps to simplify the data collection from experiments. Copyright (C) 1996 Elsevier Scie nce Ltd