JOINT DEFORMATIONS AND STRESSES OF COMMERCIAL VEHICLE FRAME UNDER TORSION

The need to include the flexibility of joints to understand the torsional properties of commercial vehicle frames is demonstrated. It can be taken into account by using flexibility coefficients or nodal substructures, ie flexibility matrices for individual frame joints. To this aim finite element idealization of the nodal regions is carried out. The range of flexibility of joints and its effect on the torsional stiffness of the frame is illustrated with an example. The flexibility of more than 50 different joints was determined by means of finite element calculation, and verified by experiment. Static and dynamic loads found in service depend on the torsional stiffness of the frame. Stresses in nodal areas can be calculated by using nodal substructures subject to boundary forces found from the overall analysis. In this way stresses may be found, which would not be expected from simple analyses. In practical cases fluctuating loads are acting on frames, which may bring about reduced torsional stiffness of bolted or riveted frames because of nodal slipping at the higher values of the loads. For the covering abstract of the conference see TRIS 391971. (TRRL)