Research On Simplified Spot Weld Model Of The Automotive Body Based On Crashworthiness Simulation

Spot welding is the primary joining method used for the construction of the automotive body structure made of steel. During crash, spot weld connections may undergo large deformation with eventual separation in critical areas. A major challenge in the crash simulation today is the lack of a simple yet reliable modeling approach to characterize spot weld separation, because most of finite element models used to date only consider spot welds using either rigid-link or rigid beam-type elements.This paper attempts to provide a simplified spot weld model which could be implemented more easily and could imitate the failure during crash more rationally and close to the real facts. The main points of this paper are as the follows:First of all, two types of simplified spot weld models—elastic-plastic beam element and spring element—are introduced to simulate separation of spot weld. The two models are being widely used for imitation abroad, whereas we often use rigid element instead.Following that, putting the three types of meld spots mentioned above into the simulation of quasi-static and dynamic axial crushing of the single hat thin-walled section respectively and comparing the results under each conditions after introducing the separation criteria, the author concludes that under the condition of quasi-static axial crushing, the three models match the actual facts reasonably, by comparison, under the condition of dynamic axial crushing, thin-walled section which connected with the elastic-plastic beam element spot weld model is better than the others.Finally, using elastic-plastic beam element spot weld model to carry out crash worthiness simulation by changing the material of bumper lining plate to high-strength steel, the author proves that it is successful to make the bumper system lightweight, and in the system which used high-strength steel the spot weld model is more stable than those in the mild steel system.