TC4钛合金微型液滴成形热应力分析

Thermal stress analysis of micro-droplets formation of TC4 titanium alloy

为研究多层液滴冷却至室温后内部残余应力分布以及新一层液滴滴下时和原来已经完全冷却区域间的残余应力分布情况,利用有限元分析软件ANSYS对TC4钛合金微滴沉积过程中热应力变化进行模拟仿真。基于参数化设计语言APDL建立有限元分析模型,采用间接耦合的方式模拟热应力,分析区域冷却过程温度场,并将温度场结果数据以载荷的形式加入结构分析中。结果表明:液滴滴落完成时温度扩散程度很小,经过一段时间冷却后,热量由液滴区域向已经冷却区域传递,最后接近于室温;后续滴落液滴区域出现了明显的收缩变形,中间区域向下凹陷;液滴区域靠近分界面附近受到拉应力,而原先冷却区域靠近分界面处受到压应力,但均小于屈服应力,说明新的一层液滴滴下和原先冷却的液滴区域不会产生开裂。

The internal residual stress distributions of multilayer droplet after cooling to room temperature and a new droplet dripping to completely cooling area were studied. The finite element analysis software, ANSYS, was used to perform process simulation of the change in the thermal stress during the deposition of titanium alloy TC4 micro-droplets. The parametric design language APDL was used to establish the finite element analysis model and indirect coupling was used to simulate thermal stress. Thus, calculations and analysis of the temperature field corresponding to regional cooling process were accomplished. The results show that temperature diffusion degree is small when the droplets finish dripping; After a period of cooling, heat transmits from the droplet area to the cooling area, and finally close to room temperature. As can be seen from the stress and strain analysis, in follow-up drip area, there is an obvious contraction deformation with middle area down concave ; Droplet area near the interface bears the tensile stress, and the original cooling area near the interface is under compressive stress, but both of them are less than the yield stress, suggesting that a new layer of droplet and original cooling area of the droplets won＇ t produce craze.