铝合金薄壁构件表面加工应力的仿真与应用

Simulation and application of surface machining stress for thin-walled aluminum alloy components

为了研究薄壁构件加工变形情况,基于特定工艺实验,提出一种外场施加表面应力的建模方法。根据零件加工应力测试实验,测得试样已加工表面应力和变形。运用MSC. Marc非线性有限元软件建立了铝合金厚板热-力准耦合模型,并运用"生死单元"技术得到薄壁框架件。分析实验表面加工应力分布特征,以细化薄壁件模型表层网格,依据圣维南原理,通过对表面局部逐块施加外场力模拟真实表面应力场。将仿真计算变形与实验对比,并进行重复性验证。结果表明:模型计算与实验结果吻合较好,两者应力值偏差小于15%,变形偏差小于20%。说明针对特定表面处理工艺进行仿真时,采用局部单元施加外场力取代繁琐的材料热力-塑变铣削计算方法,可以有效提高有限元计算效率。

In order to study the deformation condition of thin-walled components,based on the specific process experiments,a modeling method of surface stress applied to the external field was proposed. According to the part processing stress test,the surface stress and deformation of the sample were measured. The MSC. Marc nonlinear finite element software was used to establish the thermal-force quasicoupling model of aluminum alloy thick plates,and the thin-walled frame parts were obtained by the ’life and death unit’ technology. The experimental surface machining stress distribution characteristics were analyzed to refine the surface layer grid of the thin-walled components model. According to the principle of Saint-Venant,the real surface stress field was simulated by applying external field force to the local surface gradually. The simulated calculation deformation was compared with the experiment and the repeatability verification was performed. The results show that the model calculation results agree well with the experimental results,the stress deviation between them is less than 15%,and the deformation deviation is less than 20%. It shows that when the simulation is carried out aiming at a specific surface treatment process,the local unit can be used to apply the external field force instead of the cumbersome material heat-plastic milling calculation method,which can effectively improve the finite element calculation efficiency.