Case study of testing different materials for seat belt retractor torsion bar by the means of finite element analysis

This paper examines the use of various materials for the force limiter torsion bar found in an automotive seat belt assembly. We have selected the following materials: carbon steel, cast stainless steel, cast low alloy steel and cast aluminium alloy. The primary method used for this study is finite element analysis (FEA) and the use of the named materials on a 3D model of the torsion bar, constructed using the dimensions of a standard part. The 3D models were created with a 3D CAD program and the FEA analysis was carried out with special software. For the input values, the torsion bar was fixed at one corner and a 360 degree rotation shift at the other corner. A fine mesh of 1.5 mm/element was also set to get a more accurate analysis. The results of this study are in the form of stress, strain, safety factor and displacement plots generated by the FEA analysis software showing the difference between the materials. The main outcome of the study is to determine the best overall material to manufacture the part in terms of performance and cost.