Abstract: In an accident, the front and backof bodywork model can adsorb impact energy on condition that the internalspace of it has no distortion. Based on finite element LS-DYNAprogram, this paper has analyzed the model of additional mass attachingto a singlesection, the model of additional mass attaching to two sectionsproportionately, and the model whose front wall thickness is changed.According to the result, the problem is discussed of how to increase the amountof impact energy of space absorbed by the impact energy of front and back,with the internal space unchanged.