Cracks in thin structures often are subjected to out-of-plane as well as in-plane loading conditions, leading to mixed-mode I/III crack growth. In such cases, the expected large out-of-plane displacement makes both testing and modeling difficult. This paper presents the results of a research effort to study mixed-mode I/III fracture in thin specimens made of ductile materials. Understanding the behavior of thin specimens during stable mixed-mode I/III crack growth will provide important insights for the development of a general mixed-mode fracture criterion for crack growth in ductile materials. In this study, quasi-static mixed-mode I/III fracture tests were performed on cracked thin specimens made of an aluminum alloy and a steel. A full-field measurement of the three-dimensional (3D) surface displacement over a region around an advancing crack tip was recorded throughout the fracture process, which was made possible using a 3D digital image correlation system. Finite element models of the tests were developed and finite element analyses of the specimen behavior before the onset of crack growth were carried out. Comparisons show this that is an effective and reliable way for analyzing mixed-mode I/III fracture tests.
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