A comparison of multiple quasi-spherical EFP warhead tests conducted during different seasons of the year revealed that EFP velocities in the cold season were low. In this paper, the experimental phenomenon is analyzed theoretically base on the principles of EFP and flight dynamics. Due to the difference of air density caused by the different temperature, the aerodynamic drag of EFP with the same aerodynamic shape and initial velocity is obviously different. Because of the hypervelocity of EFP, The impact velocity of EFP on target is also significantly affected after flying over 100 meters. In the paper, the flight velocities of a quasi-spherical EFP at different temperatures is calculated by MATLAB, which is in good agreement with the experimental results. It is necessary to consider the change of environment temperature in engineering practice of quasi-spherical EFP warhead in order to improve kinetic energy margin.

Aiming at the high-speed cutting of D6AC high-strength steel, the forming mechanism of edge defects and the influence of cutting parameters on the degree of edge defect were analyzed by ABAQUS finite element software. The results show that there are three stages: the appearance of negative shear angle, the generation and expansion of crack and the peeling off of part substrate and chip; The cutting force increases first and then decreases during the formation of edge defect; The size of decreases with the increase of cutting speed and increases with the increase of cutting depth.