| 摘要 |
PROBLEM TO BE SOLVED: To prevent clacking due to crush deformation of an expansion part of a bumper reinforcement at the time of oblique crush by setting the ratio between the crush deformation load of the expansion part and the bending deformation load of the expansion part. SOLUTION: A ratio P1/P2 between the crush deformation load of an expansion part P1 (kgf)=(tw1+tw2)×σy×L and the bending deformation load P2 (kgf)=Mcr/(d-L/2) is set to a range of 1.6 to 4.0, where tw1 is the plate thickness of an upper or lower wall (mm), tw2 is the plate thickness of a middle horizontal wall (mm),σy is the withstand pressure of a material forming bumper reinforcement 1 (kgf/mm<2> ), L is the distance between a position at which the bending work angle of bumper reinforcement is 20 degrees and the tip end of the expansion part (mm), Mcr is the bending collapse moment of bumper reinforcement (kgf mm), and d is the length of the expansion part (mm). Thereby, the deformation form and deformation quantity during collision can be controlled.
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