LAUSR

An improved formula considering the change in densification strain is derived to predict the quasi-static crushing stress of gradient foam material. Besides, a two-displacement field is proposed to describe the deformation of negative gradient foam material under a spherical indenter. Based on those, a new analytical model is presented to predict the indentation response of sandwich panels under local loading. This model can be applied to sandwich panels with uniform, positive, and negative gradient foam cores, which are verified by simulation results using FEM software ABAQUS. Finally, the indentation responses of sandwich panels with different gradient foam cores are compared and discussed.