Low Velocity Projectile Penetration of Clay

Momentum considerations are used to establish a theoretical relationship between the instantaneous velocity, various static and dynamic soil properties, projectile characteristics, and instantaneous depth of penetration. It is assumed that projectile penetration is associated with shear failure and the resistance to the motion of projectile is provided by the inertial resistance of the accelerated soil mass plus the dynamic soil resistive force distributed over the base and shaft of the projectile. The soil resistive force is calculated on the basis of plastic theory modified for dynamic conditions and extending the previous analysis. The theoretical relationships for the velocity profile, maximum depth of penetration, and the strength of the clay target are verified with laboratory tests performed under controlled conditions with a projectile instrumented to measure acceleration/deceleration, cone thrust, and sleeve friction simultaneously and continuously.