Damage produced in laminated plastic plates by small ball collision with the velocity of 50–140 m/s

The sizes of crater and radial cracks produced by small ball collision in specimens prepared by lamination of thin plastic plates were investigated. The sizes increased with increasing ball velocity. The crater depth increased under static-bending stress. A light-mass ball produced a deeper crater than a heavy-mass ball for the same kinetic energy. In the case of static press of a ball on a plate, the circumferential strain around the contact site was changed from compression to tension and a long crack and a few very small cracks were ultimately produced, with increasing pressure. On the other hand, several radial cracks were produced by a collision. Specimen geometry influenced the crack length distribution. The influence of lamination on crack production was investigated for several combinations of laminations using various plate thicknesses. Crack length produced in a specimen supported only at both ends was slightly longer than that in a specimen with complete support.