基于DIC方法的铝合金焊接接头拉伸性能研究

为准确表征铝合金焊接接头拉伸性能,针对2219铝合金搅拌摩擦焊焊接接头,采用数字图像相关(DIC)方法,测量焊接接头在拉伸载荷作用下的全场应变历程,得到铝合金焊接接头焊接区在拉伸时的连续屈服强度曲线。进而结合材料弹塑性本构模型,拟合焊接区内各点处材料本构关系,并分别构造了铝合金焊接接头焊缝区及热影响区力学性能连续变化的拟合函数,使之可以表达铝合金焊接接头焊接区内任意一点力学性能。最后利用所构造的力学性能函数模拟了铝合金焊接接头的拉伸过程,数值结果与试验相吻合,表明基于数字图像相关法的应变测量可以准确地表征其焊接区内的材料力学性能。

STUDY ON TENSILE PROPERTIES OF ALUMINUM ALLOY WELDING JOINT USING DIC METHOD

In order to obtain the properties of 2219 aluminum alloy welding joint,this work uses digital image correlation(DIC) method,then the whole strain history within the welding zone of 2219 aluminum alloy friction stir welded joint subjected to tensile load is obtained,which in turn facilitates a continuous yield strength curve for the welding zone.The elastic-plastic constitutive equation is employed to describe mechanical properties of the welding zone with its parameters determined by the measured strain history.Then,the relationship between the distances from any location to the weld zone center and parameters in the equation can be established by fitting.Finally,a numerical simulation of welding joint subjected to tensile load is conducted using the mechanical properties given by the obtained relationship.The simulation results agree well with the experimental data.Therefore,it is proposed that the mechanical properties of the welding zone in a welding joint can be accurately obtained by analyzing its stress-strain curves measured by DIC method.