Prediction of transient displacement, velocity, and force on projectiles penetrating cohesive soils

A closed-form solution is developed for predicting transient displacement, velocity, and force as well as residual displacement and duration for both flat and pointed projectiles penetrating cohesive soils. Because transient response can be represented as a 3 parameter space of nondimensional numbers, displacement, velocity, and force are each presented in a single graph. Experimental test data for different soils and penetrator contours are used to demonstrate the validity of both transient and residual responses. Of great importance in this solution and soil dynamics in general is the advancement of a hypothesis for the dynamic interaction of intergranular stress, pore water pressure, and pore air pressure in the resisting force that retards penetration. Because fundamental dynamic pore pressure theory is used to develop this analysis, basic soil properties (cohesive yield strength, density, and degree of saturation) are used to characterize the cohesive soil.