Abstract
To satisfy the requirements for high stiffness and lightweight vehicle bodies, it is necessary to imagine the figure of the entire structure from the viewpoint of load transfer or load paths. Load transfer in structures has been studied by examining the stress or strain energy. However, when using the analyses with stress distribution, it is difficult to observe the load transfer because of the effect of stress concentration. The parameter U* has been introduced by the authors based on the internal stiffness to express load transfer under linear elastic conditions. In the present study, the index U* is applied approximately to a truck compartment under a crash process, especially at the initial stage of collision. Considering that the main part of the cab body should be remained in the linear elastic condition to ensure the safety of the occupants and introducing the method of substitution modulus, we can conclude that the linear U* analysis can be applied to cab bodies during the initial crash stage. There is no remarkable difference in the U* distribution between time steps in the initial stage. We herein propose that time t=3ms and parameter m=2 are the best options for the U* representation, which is referred to as “m2-3msU*”. This will be used as the standard condition for the U* analysis for heavy-duty truck cabs. The corner of a member plays an important role in the load transfer, and the shear effect of the front side floor conveys significant loading to the side sill. The index U* can be used more adequately than U** when the distributed loading is not remarkable under the condition of a flat barrier impact.
Keywords: Body, Structure, Structural Analysis/Load Path, Collision, U*, FEM, Safety