13th International Conference on Fracture June 16–21, 2013, Beijing, China -2- In this paper, the main task is to give the explicit Eq. (2) of a talc-filled impact modified polypropylene (PP). An empirical fracture locus depending on the parameters of stress state under both quasi static and dynamic loading was obtained using a combined experimental-numerical identification method. Different specimen geometries were designed to carry out tests of various loading conditions including uniaxial tension, simple shear, notched tension, and punching. The stress state parameters were stress triaxiality. The material model SAMP-1 [4] (a Semi-Analytical Model for Polymers) in LS-DYNA was utilized to obtain stress triaxiality evolution of failure element during the process of loading. Two different fracture predictive techniques were applied to obtain fracture locus under static loading and dynamic loading. Under dynamic loading, stress triaxiality during the loading process in each test was stable. Therefore, an average value of stress triaxiality was accurate enough to identify stress triaxiality of critical failure point during the whole loading process in each type of test. By comparing forcedisplacement curves from both test and modeling, the equivalent plastic failure strain in the identified stress triaxiality was obtained. While under static loading, stress triaxiality varied greatly during the whole loading process. Damage evolution rule was utilized to optimize failure locus. Quadratic function was selected to optimize fracture locus under static loading. 2. Methodology
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