Optimum design and vibration analysis of a naval piercing bomb for impact assessment on a fuze structure

To better understand the stresses, deformations, and high vibratory accelerations that occur within piercing bomb structures upon collision with steel ship structures, detailed finite element structural analyses were performed using realistic extreme design impact loads. The piercing bomb under consideration consisted of seven different materials, i. e., AISI4340, AISI4340F, gypsum, Al7075-T6, AISI1030, pelt, and MC-nylon. In particular, the influences of large strain and the impact acceleration along the bomb length on the fuse-protecting structure were investigated to reduce the likelihood of fuse malfunction as a result of transferred impact loads and/or acceleration. By optimizing the shape for compatibility with large impact loads, an improved structural piercing shell design was developed; the design has the same volume, but enhanced strain energy absorption. Accordingly, the strain and acceleration near the fuse-protecting structure were investigated by performing finite element analyses; they were determined to be negligibly small upon piercing impact.