焊接热循环和变形历史相关的A7N01-T6本构关系
Visco-elastic-plastic constitutive model for welding of A7N01-T6 aluminum alloy
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摘要: 建立了与焊接热循环温度和热变形历史相关的铝合金本构关系,利用MSC.MARC二次开发接口和Fortran语言,以塑性变形有限元计算增量理论为基础,开发了适用于焊接过程的材料本构关系用户子程序.采用弹塑性(混合硬化)和蠕变性质(应变软化)描述低温应变硬化特征和高温动态回复及再结晶引起的应变软化特征,不同温度的本构关系形式一致而参数不同.结果表明,焊件的残余应力和应变结果与理论结果吻合良好.与采用理想弹塑性本构关系相比,采用新开发的本构关系,高温应变软化和低温应变硬化导致等效残余应力基本不变,纵向残余压缩塑性应变较大,相应的焊接残余变形也较大.Abstract: A visco-elastic-plastic constitutive model for welding of A7N01-T6 aluminum alloy was established,considering the welding thermal temperature and deformation history. The model used elastic-mixed hardening plastic and creep equation to describe the strain hardening at low temperatures and strain softening at high temperatures,respectively. And it was applied for finite element numerical simulation of the welding process. Based on the established constitutive model,the welding residual stress and strain agreed well with the theoretical results. Compared to the ideal temperature dependent elastic-plastic model, strain hardening at low temperatures and strain softening at high temperatures had combined effect that led to invariable welding residual stress. Due to strain softening at high temperatures,the overall longitudinal residual compressive plastic strain and the maximum deformation of welding sheet were much larger using the newly proposed model.
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