Dynamic Yield Strength of Mild Steel under Impact Loading

Dynamic yield strength of mild steel is estimated when impacted by the steel balls launchedby two stage-light gas gun in the velocity region 1900-5200 m/s. The ball impact provides a radialmomentum to the target material resulting in a crater which spreads out until it is stopped bythe target yield strength. The dynamic yield strength of target metal is calculated by incorporatingthe densities of ball and target material along with experimentally measured crater radius andimpact velocity in modified Bernoulli™s equation. The dynamic yield strength of mild steel hasbeen found to be around 2000 MPa under high velocity impact, causing the material to deformat strain rates > 106 s-1. Impact phenomenon was also simulated on Autodyn 2-D using Eulerprocessor. Simulation results reveal that the target material is subjected to the highest strain rateof 105 - 106 s-1 at the impact point and then decreases as the penetration progresses through thetarget. Predicted results of crater radius depth, and splash of material match with the experimentalmeasurements.