In-plane dynamic crushing of honeycomb. Part II: application to impact

Finite element simulations were employed to analyse in-plane dynamic crushing of two different hexagonal honeycombs (slenderness ratios <f>L/t=38</f> and <f>167</f>). The response of the honeycomb with the smaller slenderness ratio was studied for impact speeds up to <f>40.0 m/s</f> which corresponds to a nominal strain rate for the specimen of <f>500 s−1</f>. Total plastically dissipated energy was used to quantify the effects of increasing strain-rate, since other measures showed a strong dependence on details of the finite element model. The simulations revealed a strong increase of total dissipated energy with increasing impact speed for velocities larger than the critical speed for wave trapping, <f>vcr</f>. One reason was a higher percent of cells collapsing in a symmetric crush mode (IV). Another reason for the larger total dissipation at higher crushing speeds was the greater irregularity in the folding pattern that developed. Experimental and calculated global force-time curves were compared for the honeycomb with the larger slenderness ratio at impact speeds <f>3.0</f> and <f>7.2 m/s</f> and a satisfactory agreement was found. At these low impact speeds there was no increase of initial collapse or plateau stresses. A comparison of sequences of deformed mesh plots and high speed photos showed good correlation of the general distribution and modes of crushing. [Copyright &y& Elsevier]