LY12铝合金搅拌摩擦焊接头残余应力分析

采用小孔法对不同焊接工艺参数下得到的LY12铝合金薄板搅拌摩擦焊对接接头的残余应力进行了测量和分析.为了消除孔边塑性变形对测量精度的影响,建立了三维有限元法模拟应变释放系数的测量试验,使用基于孔边形状改变比能的A,B系数修正法对盲孔释放系数进行修正.结果表明,接头残余应力呈不对称分布,前进侧应力高于返回侧;纵向残余应力总是高于横向残余应力,但是横向残余应力并非在零附近,而是有一定的大小,约为焊前母材强度的10.8%;在一定范围内,搅拌摩擦焊接头残余应力随旋转频率先增大后减小,随下压量和焊接速度的增加而增加.

FSW residual stress of aluminum alloy LY12

The residual stres for friction stir welded Al alloy LY12 plates at different parameters was studied by using the blind-hole methods.To release the influence on the measuring accuracy of high welding residual stress when the hole drilling method was used, three dimensions finite element model was developed to simulate the test of the strain releasing coefficients.The strain releasing coefficients A and B were corrected based on the energy parameter which was obtained by the FEM analysis results.The results showed that longitudinal residual stresses were asymmetrically distributed at different sides of the weld center and it was high at the advancing side and relatively low at the retreating side.The transversal residual stresses are not equal to zero but about 12.7% of base metal.The residual stresses will become larger firstly and then decrease with the rotation rate increasing and become larger and larger with the pressed-in and welding speed increasing.