Multi-Purpose Auxetic Foam with Honeycomb Concave Micropattern for Sound and Shock Energy Absorbers

Abstract

Porous materials have been widely used for passive energy absorption in various applications including aerospace systems, automotive vehicles, and electronic products, due to high energy dissipation and sound absorbing mechanism in a wide frequency band. However, most porous materials have a critical problem in poor mechanical properties that inhibit their application to shock absorbing structures. Herein, a multi-purpose auxetic structure is reported that has a highly ordered honeycomb concave micropattern on the surface of the auxetic foam through non-solvent induced phase separation. Most importantly, the dimensions of the concave micropatterns can be easily controlled depending on the non-solvent ratio. The energy absorption performance and mechanical strength are significantly enhanced by adopting concave micropatterns on the curved surface in the auxetic foam. The superior energy absorption performances of the multi-dimensional auxetic foam are improved by 37.5% in view of an average sound absorption coefficient, and the improved mechanical properties are verified by systematically investigating porous properties such as tortuosity, porosity, apparent density, and total pore area. In addition, the proposed multi-purpose auxetic foam exhibits a remarkably improved shock energy dissipation capacity, which reduces impact force by 34% compared with that of bare polyurethane foam in a low-velocity impact test.