Numerical simulation of Ti/Al/Mg impedance-graded structure under hypervelocity impact

The effects of Ti/Mg thickness ratio (abbreviated as Ti/Mg ratio), structural thickness/projectile diameter (t/D) ratio and impact angle θ on the hypervelocity impact characteristics of Ti/Al/Mg impedance gradient structures were studied with AUTODYN finite element software. Results show that the influence of Ti/Mg ratio on the expansion characteristics of the outer bubble fragment cloud is within 5%, but increasing the Ti/Mg ratio can improve the degree of fragmentation of the projectile. The structural energy absorption characteristics are best within the range of 0.625 to 1. The expansion speed of the outer bubble fragment cloud and the mass of the large fragment at the center of the projectile decrease with the increase of t/D ratio, while the unit face density energy absorption decreases. Oblique impact is beneficial to the dissipation of projectile kinetic energy by the impedance gradient structure, but it will reduce the degree of fragmentation of the projectile. After θ exceeds 40° or 50°, the "slip effect" has a significant impact on the impact characteristics of the impedance gradient structure. The perforation area of the impedance gradient structure decreases with the increase of Ti/Mg ratio and t/D ratio, and increases with the increase of θ, and an empirical formula for the dimensionless perforation area of the impedance gradient structure is obtained based on dimensional analysis.