A Mixed-Mode Controlled DCB test on adhesive joints loaded in a combination of modes I and III

Abstract

This work presents a novel test setup to determine the fracture behavior of adhesive joints subjected to mixed-mode I+III loading. Common mixed-mode tests are mainly focusing on a combination of modes I and II and are limited to approaches derived from linear-elastic fracture mechanics with respect to the test evaluation. The novelty of the here proposed test is based on the principle of superposition of modes I and III, which holds in case of non-linear elastic fracture mechanics as well. The definition of mode-mixity in terms of contributions to J-integral from single modes allows controlling of mode-mix ratio during experiments. The mode-mixity can be prescribed arbitrarily and the test evaluation is possible also in case of crack propagation. As an outlook, that test setup could be used to study the dependency of fracture behavior on the load history. The experimental work deals with an elastic-plastic epoxy adhesive, SikaPower®-498. The adhesives is investigated under several constant and variable mode-mix ratios.