Songlin Xu

Experimental and numerical study of the effect of micro-structure on the rate-sensitivity of cellular foam

ABSTRACT Understanding the dynamic behavior of cellular foam is essential for designing anti-collision structures. In this work, the rate-sensitivity of cellular foam was analyzed on dynamic experiments of split Hopkinson pressure bar and finite element methods (FEM). A typical circular ring structure is introduced in the FEM analyses to estimate the effects of the post-buckling behavior of cell walls on the properties of stress enhancing as the strain rate increases. The quadrilateral/circular honeycomb foam structure is used to estimate the contribution of micro-structure and matrix effects. These results show that the post-buckling of a micro-structure is an important rate-sensitivity factor.

Modification of the contact surfaces for improving the puncture resistance of laminar structures

Uncovering energy absorption and surface effects of various penetrating velocities on laminar structures is essential for designing protective structures. In this study, both quasi-static and dynamic penetration tests were systematical conducted on the front surfaces of metal sheets coated with a graphene oxide (GO) solution and other media. The addition of a GO fluid film to the front impact surface aided in increasing the penetration strength, improving the failure extension and dissipating additional energy under a wide-range of indentation velocity, from 3.33 × 10−5 m/s to 4.42 m/s. The coated -surfaces improved the specific energy dissipation by approximately 15~40% relative to the dry-contact configuration for both single-layer and double-layer configurations, and specific energy dissipations of double-layer configurations were 20~30% higher than those of the single-layer configurations. This treatment provides a facile strategy in changing the contact state for improving the failure load and dissipate additional energy.