Evaluation Using Digital Image Correlation and Finite Element method of Stress Intensity Factors and T-stress

摘要

A controlled crack growth in PMMA was achieved in Wedge-Splitting Test (WST) by regulating the cross-head speed of loading by a computer-driving testing device.The fracture behavior of a crack propagating was investigated quantitatively by both numerical modeling and experiment using Finite Element Method (FEM) and Digital Image Correlation (DIC).A twoparameter fracture mechanics approach,describing the near-crack-tip stress field,was applied to determine the stress intensity factor (SIF) and the coefficient of higher order term (T-stress).In both methods,it was shown that the stress intensity factor versus crack length remains constant whereas the T-stress varies from negative to positive.This later variation is similar to the three point bend beam,but different from the compact tension specimen,for which the T-term is always positive.Using Digital Image Correlation (DIC),the stress intensity factor and T stress were estimated with 10％ and 15％ uncertainty in a complex loading set-up without having to do a numerical modeling of the experiment.