Modeling the effect of the striker geometry on the wave propagation pattern in the Split-Hopkinson pressure bar test using the discrete element method

Split Hopkinson Pressure Bars (SHPB) test is widely used among the various methods for investigating the dynamic behavior of rocks at high strain rates. Various factors affect the waveform and the results of this test. In this study, the aim was to investigate the effect of geometrical parameters of strikers including the effect of shape, length, and impact cross-section width (ICSW) on the waveform induced in the SHPB test using numerical modeling. For this purpose, in the first stage, the required information including geometrical properties and the required micro-parameters have been collected from two laboratory and numerical modeling studies. Then, the initial model was constructed using the discrete element numerical method (DEM), and its results were compared with laboratory and numerical results. Evaluation of the effect of striker shape demonstrated that SS strikers have induced a semi-sinusoidal wave and CS strikers have induced a quasi-rectangular wave. Among the waveform properties, the wavelength was strongly related to the geometric properties of the strikers in both CS and SS types in a way that was directly related to the striker’s length and inversely related to the ICSW. On the other hand, the maximum amplitude is directly related to the striker’s length and ICSW in both CS and SS types. According to the results, the use of SS strikers is more appropriate according to the waveform, and its geometric properties can be determined according to the problem requirement, using numerical modeling results.

Keywords:

Hopkinson Bar Test , Dynamic Modeling , Waveform , Discrete element method , PFC۲D Software