Improving the crashworthiness of space frame based vehicles using composites

Abstract

This research paper details the investigation into the capability of increasing the crashworthiness of a space frame based vehicle, by the implementation of a modern composite reinforcement technique. This study involves using quasi-static axial compression testing, which is performed on standard structural square and round tubular sample elements of a space frame and specimens of same dimensions which have been reinforced by an exterior cladding of three and five layers of prepreg composite carbon fibre. Each of these samples are presented in two different lengths of 100mm and 200mm, these lengths are chosen due to being longer and shorter than the critical length of the chosen type of tubing. This is to polarise between local and global buckling and is used to represent longer and shorter structural elements used as part of a space frame, which will undergo global and local buckling failure mode during a collision, respectively. Results from testing are then used to compare characteristics such as the energy absorbency, specific energy absorbency, maximum load and overall failure mode by processing the force / displacement data derived from the quasi-static compression testing, overall observation of testing and dissection and inspection of tested specimen samples. In addition to real life mechanical testing, FEA and first principle calculations have been utilised to maintain a scientific and critical approach. Upon analysis of data derived from mechanical testing, it was evident that the composite reinforcement technique played a very large role in increasing energy absorbency and specific energy absorbency of the specimen samples, the most notable being the longer sections which underwent global buckling in their plain, unreinforced state. The composite reinforcement enabled these longer sections to fail in a more desirable local buckling mode, increasing the SEA by up to 703%.