【摘要】 模拟实验加载条件,采用理想弹塑性本构模型,将TC4钛合金电子束焊接试件划分成焊缝、热影响区和母材三个区域,分别赋予不同的强度极限,同时考虑热影响区强度极限的梯度分布,建立有限元模型,分析葫芦型、倒钟罩型、楔型和丁字型等不同焊缝形貌焊件的应力和疲劳寿命分布,沿不同观察路径考察应力分布的规律.比较发现,不同焊缝形貌的接头都在焊缝区域形成比较明显的应力集中,而且不同形貌接头的应力分布在焊缝和热影响区差别较大,但在远离焊缝的区域差别很小;应力集中造成焊件疲劳寿命分布的不均匀,从而降低焊件的疲劳寿命,焊趾附近为低疲劳寿命区域,疲劳破坏容易从焊趾处起源;楔型焊缝焊趾处应力集中较小,疲劳寿命最长.更多还原

【Abstract】 The experimental loading conditions are used,and the ideal elastoplastic model is considered as the constitutive relation in this paper.The electron beam welding specimens made of TC4Titanium alloy are divided into three zones with different ultimate strengths,namely weld seam,heat-affected zone and base metal,and the gradient distribution of the material strength in the heat-affected zone is also considered.The finite element models are created in order to analyze the distribution of stress and fatigue life in the electron beam welding specimens with four kinds of seam shapes,namely tundish shape,bell shape,wedge shape and nail shape.The method is validated by comparison between the simulation results and the experimental ones.It is shown that(1)the stress concentration occurs in the weld seam zone,and the stress distributions of welding specimens with different seam shapes are very different in the weld seam and heat-affected zone,but very approximate in the base metal;(2)the uneven distribution of weldment life caused by stress concentration reduces the fatigue life,and the life near the weld toe is lower so that the fatigue failure usually starts at the weld toe;(3)among all the discussed specimens,the wedge-shaped specimen has the longest fatigue life.更多还原