高应变率下不锈钢激光焊缝塑性流动及本构行为研究

Laser welding is widely utilized in the frame structure and energy absorber of automobiles and urban rail trains. During collision of welded structure, welded joint will experienced complex deformation state such as tensile, bending and buckling et.al. It is necessary to research the dynamic plastic and failure properties of the welded joint. In this project, we attempt to develop an experimental method to obtain dynamic mechanical properties of the welded joint by using SHP(T)B and DIC without separating of welded material from the welded joints. The effect of strain rate on dynamic strength and failure of welded joint and the strain rate related constitutive parameters will be systematically researched. The effectiveness of the constitutive parameters will be examined by the comparison of simulated and exprimental results of axial impact test of square tube. Meanwhile, some progresses of dynamic testing method are also expected in this work.

激光焊接在汽车及城市轨道车辆车体框架结构及冲击防护装置中被广泛的采用。焊接车体在碰撞过程中会发生拉伸、弯曲及屈曲等更为复杂的变形行为，局部应变率可达10^3/s以上。因此，开展焊缝在冲击载荷作用下的动态塑性及失效行为研究就显得十分重要。本项目试图利用DIC测试技术与霍普金森杆装置，发展在不分离焊缝的情况下获取焊缝材料动态力学性能的实验方法，研究不锈钢激光焊缝材料高应变率下的塑性流动及失效特性，分析应变率对焊缝材料屈服强度及失效应变等力学参量的影响规律，拟合其相关本构参数；最终利用焊接方管塑性渐进屈曲行为的预测验证材料参数的有效性。通过上述工作，为车体中不锈钢激光焊接结构的优化与扩展应用提供定量的分析方法和理论依据。

激光焊接在汽车及城市轨道车辆车体框架结构及冲击防护装置中被广泛的采用。焊接车体在碰撞过程中会发生拉伸、弯曲及屈曲等更为复杂的变形行为，局部应变率可达10^3/s以上。开展焊缝在冲击载荷作用下的动态塑性及失效行为研究就显得十分重要。本项目利用DIC测试技术与霍普金森杆装置，发展了在不分离焊缝的情况下获取焊缝材料动态力学性能的实验方法，获得了不锈钢激光焊缝材料高应变率下的塑性流动及失效特性，分析获得了应变率对焊缝材料屈服强度及失效应变等力学参量的影响规律，拟合获得了其相关本构参数；最终利用结构塑性渐进屈曲行为的预测验证材料参数的有效性。通过本项工作，为车体中不锈钢激光焊接结构的优化与扩展应用提供定量的分析方法和理论依据。