Verification of Impact Energy Delivered by a Drop Weight

Impact sensitivity of energetic materials is an important parameter for their safe handling and storage.The drop height or equivalent potential energy that is required to reach a certain probability of initiation in repeated tests is determined using a drop-weight instrument.In this work, photonic Doppler velocimetry was used to measure the drop weight velocity profile during its fall and rebound.Numerical simulations were performed to correctly understand the velocity records and to find out the differences from the ideal behavior.The efficiency of the conversion from the potential to kinetic energy was revealed for various drop weight masses and drop heights.The measured velocities at the moment of impact followed the free-fall predictions to within 1%.The energy conversion efficiency decreased from 0.997 to 0.992 with the drop weight decrease from 10 to 0.5 kg.The relative energies of the rebound drop-weights decreased with decreasing mass from >0.75 at 2-10 kg down to <0.4 at 0.5 kg.The PDV instrumentation was found useful for validating the drop-weight velocity.The resting times and rebound velocity profiles of the drop-weights agreed with the numerical simulation results that assumed elastic behavior of the instrument.