Redesign of the ECT Test for Mode III Delamination Testing. Part I: Finite Element Analysis

Abstract

A series of finite element analyses (Part I) and tests (Part II) on various modifications of the edge crack torsion (ECT) test have been conducted in an effort to render the test more suitable for characterizing mode III delamination in laminated composites. To this end, two ECT specimen configurations were considered. The first configuration involves loading the specimen at a single location, and the second configuration involves a symmetric double load point application. Investigations were conducted on the effect of specimen overhang, along the length and width direction, on the inferred strain energy release rate distributions across the delamination front. Stress distributions in the vicinity of the delamination front were used to infer the corresponding modes I, II, and III strain energy release rate distributions. Results indicate the single and double loading configurations exhibiting similar stress distributions along the delamination front. Specimens with short crack lengths and small amounts of overhang yielded the most uniform distribution of mode III loading along the delamination front.