Plastic collapse of thin-walled frusta and egg-box material under shear and normal loading

The quasi-static plastic collapse of thin-walled frusta is determined for combined shear and out-of-plane compression. Experiments and finite element calculations are conducted on conical metallic frusta with semi-included cone angles of 30ο and 45° to determine the shear collapse response. Additional finite element predictions are given for compressive loading, and for combined shear-compressive loading. The dependence of strength and energy absorption upon geometry is explored. The predicted response of an array of conical frusta is used to give the overall response of an egg-box material sandwiched between rigid face sheets. Scaling laws are determined for the stiffness and strength as a function of relative density of the egg-box material.