The Effect of Joint Flexibility on the Torsion of a Vehicle Body

Abstract

Experiments on thin fabricated box members in a tee joint configuration revealed deformations which could not be correlated with beam-type models, even when spring elements were introduced at the joint. The behaviour was also observed in finite element analyses of the joints.

Part of the cab structure of a heavy goods vehicle which formed a plane frame with fabricated members of closed cross-section was tested in torsion and the stiffness compared with theoretical predictions. The application of classical beam and torsional theory gave a result which was approximately ten times the experimental value. A further theoretical estimate, which included the joint flexibility as predicted by a finite element model of the localized region at the joint, gave an improved result which was 26 per cent higher than the experimental value.