铝合金微滴打印沉积制造中热应力3D动态仿真分析研究

A 3D dynamic simulation analysis of thermal-mechanical coupled duriduring Aluminum Alloy micro-droplet deposition manufacture

摘要:

翘曲、分层、开裂是7075铝合金微熔滴沉积制造过程中常见的缺陷，其原因主要是沉积制造过程中存在较大的温度梯度和热应力集中。为了探究热变形、翘曲和开裂的形成机理，采用有限单元法和单元生死技术，通过ＡＰＤＬ(ANSYS)编程，建立了气动按需熔滴沉积成形温度和热应力计算模型，分析了7075铝合金微熔滴逐点、逐层沉积三维制件过程中温度和热应力的动态演变规律。并使用7075铝合金微滴，在相同初始边界条件和工艺参数下进行了沉积试验，模拟结果与7075铝合金制件微熔滴沉积试验结果基本吻合，较好地反映了实际成形过程中零件的温度和热应力场变化规律，为减少或消除铝合金微熔滴沉积制造过程的缺陷提供了理论依据，从而促进了该技术在高熔点合金零件制备中的应用。

Abstract:

In aluminum alloy droplet deposition manufacture，thermal warping，layering and hot cracking of formed 3D components are the most common defects, which have been found to be associated with the larger temperature gradient and thermal stress concentraction. To obtain insight into the common defects formation mechanism in metal micro-droplet deposition manufacture, a 3D transient finite element (FE) simulation model has been developed by using the APDL(ANSYS) code and element brith-death technique. The distribution and variation of time-dependent temperature and thermal stress fields were predicted and the thermo-mechanical behaviors were analyzed in fabricating aluminum alloy 3D components. And then, a series of deposition experiments were conducted using 7075Al alloy droplets under the setting process parameters(Same to the simulation initial and boundary conditions). The experimental results show that the experimental results basically agree with the simulation results of thermo-mechanical behaviors. The reliability and correctness of the simulation model were verified experimentally by the measured temperature field and the observation of thermal deformation and hot cracking of formed 3D component. The work provides an useful theoretical and experimental guide for optimizing metal droplets deposition manufacture.