Study on the critical velocity for initiation of a covered explosive by fragment impact

This study examines the critical velocity for initiating a covered explosive via fragment impact, crucial for enhancing ammunition safety and reliability. Using numerical simulation techniques, the initiation threshold and influencing factors under non-normal impact conditions are investigated, which are more relevant to battlefield scenarios. The Jacobs-Roslund formula for NTO based insensitive explosive is calibrated, which is applicable for both flat-nosed and standard conical-nosed fragments. To account for a large range of impact angles, a correction term is introduced, and the predicted values are in good agreement with the simulation results. The effects of fragment pitch, yaw, and charge curvature on the critical velocity are found to be minimal at impact angle not exceeding 25°.