Thermoelastic Stress Analysis of modified Transverse Cut Tensile composite specimens under pure Mode II fatigue delamination

Abstract

The present work investigates the behaviour of a Transvers Crack Tensile (TCT) specimen undergoing fatigue loading, by means of a Thermoelastic Stress Analysis (TSA) experimental setup. The TCT is a tensile composite specimen where a number of internal layers are cut through the beam width. The presence of such transverse notch favours the formation of interlaminar Mode II delaminations, starting from the notch tips and propagating between the cut and continuous plies. In this work, a modification is adopted to the classic TCT specimen, where insert films, mimicking artificial delaminations, are laid across the notch tips. This is done with the purpose to favour a pure Mode II and a symmetric and simultaneous delamination. The modified-TCT has been subject to cyclic sinusoidal loading, typical of fatigue characterisations, and monitored at various crack growth stages by TSA. CFRP and GFRP samples have been prepared and analysed, measuring the thermoelastic signal from the edge and front faces of cycling samples. The information gained from TSA has provided a useful insight on the stress distribution settling near the crack tips, and its evolution with crack growth under fatigue. Copyright (C) 2018 The Authors. Published by Elsevier B.V.