Strain-rate-dependent failure criteria posites . Daniel ?, . Werner, . Fenner Robert McCormick School of Engineering and Applied Science, Northwestern University, 2137 Tech Drive, Evanston, IL 60208, USA article info Article history: Received 8 July 2010 Received in revised form 15 September 2010 Accepted 30 November 2010 Available online 4 December 2010 Keywords: A. Polymer–posites (PMCs) B. Mechanical properties B. Strain rate effects C. Failure criterion D. Dynamic testing abstract The objective of this study was to characterize the quasi-static and dynamic behavior posite mate- rials and develop/expand failure theories to describe static and dynamic failure under multi-axial states of stress. A unidirectional carbon/epoxy material was investigated. Multi-axial experiments were con- ducted at three strain rates, quasi-static, intermediate and high, 10 ? 4, 1 and 180–400 s ? 1, respectively, using off-axis specimens to produce stress bining transverse normal and in-plane shear stres- ses. A Hopkinson bar apparatus and off-axis specimens loaded in this system were used for multi-axial characterization of the material at high strain rates. Stress–strain curves were obtained at the three strain rates mentioned. The measured strengths were evaluated based on classical failure criteria, (maximum stress, maximum strain, Tsai–Hill, Tsai–Wu, and failure mode based and par
