Numerical Simulation Of Shock Wave Propagation In Granular Layers

The propagation of shock waves in the granular layers plays an important role in studying the dynamic response of the particles after impact,and for the energy absorption and dissipation of particles during the interaction.Based on the discrete element numerical simulation method,we have simulated the process of shock wave acting on granular layer,studied the variation of the velocity of shock wave in different granular layers,and the attenuation law of the pressure.We have given the influence of various factors on the interaction between shock wave and particle,such as the properties of particle material,granular layers height,granular layers diameter,container material,the size of loading and the times of shock.By tracking the trajectory of the shock wave in the granular layers,we get a typical shock wave pressure signal of shock wave in the granular layers.Comparing with the pressure signal measured by the experiment.we found that the length of the particle column has an effect on the measurement of the experimental signal.In the short particle column,the interval between the incident wave and the reflected wave is very short,it will result in a strong peak in the granular layers pressure,so it is difficult to measure the peak pressure of the granular layers under the action of incident wave.By comparing particle columns of different sizes,we find that the shock load in the granular layers is independent of the height of the particle columns and is related to the diameter of the particle columns.By the change of the dimensionless pressure in the granular layer with the depth of the granular layer,it is found that the initial shock load does not affect the decay rate of the shock load in the granular layer.From the top to the bottom of the particle column,the dimensionless axial pressure decreases linearly with the dimensionless depth;the dimensionless radial pressure will increase first,then descend gently and then descend rapidly.By changing the material properties of the particles and the wall of the vessel,it was found that the effect of particle density on the axial and radial forces in the granular layer was not significant,but the increase of the grain hardness significantly weakened the axial and radial pressure in the granular layer.The effect of the hardness of the sidewalls on the axial and radial compressive forces in the granular layers is related to the hardness of the particles themselves.For the soft particles(resin particles),the axial and radial pressures of the resin sidewall are significantly larger than the steel sidewall;for the hard particles(quartz sand),the axial and radial compressive forces are slightly larger than the resin side wall.