关键词: 激光直接成形, 热力耦合场, 数值模拟, 钛合金

Abstract: The research is focused on the relationship between the thermal field and thermal stress field during the process of the blade direct laser forming, so as to improve the forming quality. A hollow blade has been taken as example. According to the blade scatter-plot measured by the laser measurement instrument, the blade outline is approximated by a series of arc splines. Using finite element software MSC.Marc, a finite element model of arc approximation of the Ti-6Al-4V (TC4) hollow blade is established, and the hollow blade of laser direct forming is simulated to acquire the thermal field and thermal stress field in the forming and cooling process. During the forming process, the temperature of the forming hollow blade is increased and thermal stress of the already formed parts constantly changes with the thermal cycle due to the heat accumulation. And the part with a smaller curvature radius has a greater thermal stress which is affected by thermal cycle slightly. After the forming process, the reduction of the whole temperature leads to the thermal stress of every part rising gradually. Moreover, analyzing the distribution of the thermal field and thermal stress field, the correlation between the curvature radius and thermal field and thermal stress field can be obtained. The forming method of improving the quality is put forward based on the simulation result, summarized correlation, and experience. Finally, the real part just like the simulation model is worked out by utilizing the laser direct forming technology to verify the correctness of the simulation and summarized relationship.

Key words: Direct laser forming, Numerical simulation, Thermo-mechanical coupling coupled field, Titanium alloy