The influence of pin on the low-velocity impact performance of foam sandwich structure

In this study, experimental and computational approaches are used to explore the influence of relative position parameter (ratio of the axial distance between the impactor and the pin to the sum of their radius) and dimensional parameter (ratio of impactor diameter to pin diameter) of pin and impactor on foam core sandwich structure under the low-velocity impact. First, sandwiches with various specifications were subjected to low -velocity impact tests with an energy of 34 J. Then reinforcing effect of the pins and the specimen damage condition were thoroughly evaluated using finite element analysis (FEA). The findings revealed that the enhancement impact was substantial when position parameters were below a value of one and was negligible when position parameters were greater than three. In addition, the deformation and damage patterns of the pins gradually transitioned from crushing to large curvature bending, micro-buckling, and negligible deformation were observed with increasing values of position parameters. To establish the law associating position and dimensional parameters with impact performance (including maximum contact force, resistance to impact damage, perforation threshold energy and dent depth), experiments were designed by the central composite design (CCD) method and simulated through FEA. The analysis of variance revealed that the position parameter have higher significance on the maximum contact force, damage resistance and perforation threshold energy, while the dimensional parameter have higher significance on the dent depth. Finally, a parameter optimization design approach was proposed that increased the sandwich's perforation resistance and damage resistance.