Factors affecting the torsional properties of box sections, Ironmaking and steelmaking

Although considerable data exist on the static and dynamic properties of single resistance spot welded joints and simple adhesively bonded joints, there are less data concerning the mechanical properties of more complex structural components. In addition, information on simple joints does not provide a realistic indication of the performance of structures in service, where joint interactions influence behaviour, and structural design has a significant effect on performance. The automotive body in white (BIW) structure is made up of many components, all contributing to the overall rigidity of the structure. If a component of the BIW can be stiffened by means of an improved design, it is logical to assume that the overall rigidity of the BIW can be increased by similar means. In test programmes, box hat structures or box sections are commonly used to represent automotive components such as pillars and sills. This paper presents an experimental and numerical study to determine the torsional stiffness, elastic limit, and ultimate strength of spot welded, adhesively bonded, and weldbonded box sections. A variety of factors were investigated, using factorial design techniques to determine their effects on the torsional properties of box sections. The effect of load transfer on the torsional properties of spot welded closed top hat (CTH) sections and the difference in torsional properties between weldbonded and adhesively bonded CTH sections were also investigated. The joining system used, the area of the section, and the section thickness were found to be the most important factors in determining the torsional stiffness of the sections, whereas the substrate strength was the most important factor in determining the elastic limit and ultimate strength of the sections