高强钢闭口帽形结构准静态轴向压溃实验

Experimental Study on the Quasi-Static Axial Crush Response of High Strength Steel Closed-Hat Structures

为了研究成形历史对车身部件冲击变形行为的影响,以点焊连接闭口帽形结构为例,比较了2种高强钢材料———HSLA340和DP590不同成形条件下准静态轴向压溃过程的变形模式和吸能特性.实验结果表明:冲压成形过程导致的结构局部材料强化和几何弱化现象严重影响了帽形结构压缩过程中的屈曲变形模式,使其吸能能力低于折弯构件;大压边力冲压成形构件压溃过程中出现局部板材撕裂现象,该现象与应变历史及应力状态相关;因其独特的低屈强比硬化特性,不同成形条件下的DP590构件变形吸能特性始终优于HSLA340构件.

In order to study the influence of forming history on the crash behavior of auto-body component,axial crush behavior and energy-absorption performance were compared on the spot-welded closed-hat structures fabricated with different forming conditions for two high strength steels,HSLA340 and DP590 respectively.It was proved that the local material strengthening and geometry weakening resulted from the stamping process significantly affect the post-buckling mode of the hat structures subject to axial loading condition.As a result,the energy absorption of stamped components is lower than that of bent component.In addition,the sheet metal tearing is observed on the crushed components formed under high blank-holder-force stamping condition,which is believed to be dependent on both the strain history and stress state.Due to the special character of low yield/ultimate strength ratio of DP590,the energy-absorption performance of DP590 components is always superior to that of HSLA340 components.