高强铝合金薄板搅拌摩擦焊残余应力及变形的热力耦合模拟

Thermal-mechanical coupled simulation on residual stress and distortion of high-strength aluminum alloy sheet after friction stir welding

针对航空领域中常用的7B04高强铝合金,基于剪切摩擦生热理论,建立了适用于薄板搅拌摩擦焊(FSW)过程的自适应热源模型,利用有限元软件MSC.Marc建立了FSW过程的热力耦合有限元模型,并通过子程序二次开发,将建立的热源模型载入到有限元模型中,对7B04铝合金薄板的FSW过程进行瞬态热力耦合模拟。预测并分析了FSW过程中铝合金板材内部的温度分布与演化、焊接接头附近区域的残余应力分布及板材的最终变形情况,通过开展FSW工艺试验从温度场和残余应力两方面对模型的可靠性和模拟结果的准确性进行了验证。此外,利用经过验证的有限元模型对搅拌头机械载荷在残余应力和变形中的影响作用进行了深入分析。

For 7B04 high-strength aluminum alloy commonly used in the aviation field, based on the theory of shear friction, an adaptive heat source model was developed for the friction stir welding （FSW） process of sheet metal. A finite element model of FSW process was established by using the finite element software MSC. Mare. Then, the heat source model was integrated into the finite element model to simulate the FSW process of 7B04 aluminum alloy sheet through the subroutine. As a result, the temperature distribution and evolution of the aluminum alloy sheet during the FSW process, the residual stress distribution in the vicinity of the welded joint and the final deforma- tion of the plate were predicted and analyzed. The reliability of the model and the accuracy of the simulation results were verified by the FSW process test from two aspects of the temperature field and the residual stress. In addition, the effect of mechanical loading of welding tool on residual stress and distortion was analyzed by using the verified finite element model.