Strain Rate Concentration Factor for Double-Edge-Notched Specimens Subjected to High Speed Tensile Loads

13th International Conference on Fracture, June 16–21, 2013, Beijing, ChinaEngineering plastics provide superior performance to ordinary plastics for wide range of the use. For polymer materials, dynamic stress and strain rate may be major factors to be considered when the strength is evaluated. Recently, high speed tensile test is being recognized as a standard testing method to confirm the strength under dynamic loads. In this study, therefore, high speed tensile test is analyzed by the finite element method; then, the maximum dynamic stress and strain rate are discussed with varying the tensile speed and maximum forced displacement. The strain rate concentration factor found to be constant independent of tensile speed, which is defined Ktέ as the maximum strain rate appeared at the notch root over the average nominal strain rate at the minimum section. The maximum strain rate is controlled by the tensile speed alone independent of the magnitude of the forced displacement. It is found that the difference between static and dynamic maximum stress concentration (σmax-σst) at the notch root is proportional to the tensile speed when u/t≦5000mm/s