Numerical analyses of sandwich panels with triangular core subjected to impact loading

Sandwich panels made of metal sheets with unfilled cellular cores are found to exhibit lower deflections compared to an equivalent monolithic plate of same metal and similar mass per unit density. The structures having such sandwich panels are suitable under impact loading due to low deflection. However, the process of localized impact on solid structures is quite complicated involving plastic deformation, high strain rates, temperature effect, material erosion, etc. Further, the sandwich panel having triangular corrugated core depends on various design parameters such as thickness of front plate, thickness of back plate, thickness of core, thickness of webs, and angle of web. The influences of these parameters on the structural performance are studied while designing a triangular corrugated core structure for improved ballistic limit for a given mass per unit area. In this research, a numerical analysis of impact of empty triangular corrugated core sandwich panels by ogive nose steel rod projectiles is carried out. Design parameters of the corrugated structure; namely web thickness, core thickness, web angle, front and back plate thickness are varied; and residual velocity of projectile is obtained for each case. Impact at webs resulted in higher projectile retardation and deflection than impact at the base of the prism. For base impacts, improvement in ballistic performance at minimum cost of structural weight can be achieved by increasing web angle or front or back plate thickness, while the same can be achieved for web impacts by increasing web thickness. Since web impacts experience higher penetration resistance than base impacts, designing the panel using optimum design parameters for web impacts is desirable.