Dynamic responses of metal sandwich beams under high velocity impact considering time inhomogeneity of core deformation

The objective of this paper is to establish a yielding criterion for a sandwich beam by considering the time inhomogeneity of foam core deformation, which results in the time-varied neutral surface and cross-sectional area. Taking into account of the bending and axial stretching, a unified dynamic yielding criterion for metallic sandwich beams considering the mass redistribution along with the core compression is established. A membrane factor is proposed and an analytical solution for the large deflection of the beam under high velocity impact is given. Different from the traditional yielding surface, when the core is partially densified, the yielding surface is asymmetric. Comparison of analytical solutions with numerical ones reveals that the present model improves the prediction accuracy of high-velocity impact responses of fully clamped sandwich beams. The present method can also be degenerated to predict the low velocity/energy impact responses of sandwich beams.