Experimental and numerical investigation on energy absorbing characteristics of empty and cellular filled composite crash boxes

Composite structures have been used in the automotive and aircraft industries because of their superior properties such as specific energy absorption ability, lightweight and crashworthiness. This paper aims to determine energy absorbing and deformation behaviours of composite crash boxes designed in different geometries by an innovative approach. The hand-layup vacuum bagging method was utilized to produce the composite crash boxes, which were developed with three different outer wall geometries (square, hexagon, and cylinder), and cellular filled square and hexagonal interiors. Carbon fibre reinforced polymer (CFRP) material was used in fabrication of the crash boxes. Experimental and numerical studies were conducted to investigate the energy absorbing and deformation behaviours under static compression load of the composite crash boxes. A commercial finite elements (FE) software (Ls-Dyna) was used for the numerical model. The study's findings revealed that cellular-filled composite crash boxes perform significantly better in terms of energy absorption performance. It was observed that filling an empty square type composite crash box with hexagonal cells increased the box's specific energy absorption capacity by around 140%.