钛合金激光沉积修复热力耦合场的研究

发布时间：2018-06-01 09:08

本文选题：温度场 + 应力场　；参考：《沈阳航空航天大学》2015年硕士论文

【摘要】：激光沉积修复技术(Laser Deposition Repairing Technology)是将激光快速成形技术与激光熔覆技术相结合起来发展的一种先进的增材制造技术,该技术可以修复任意复杂形状零件存在的损伤及制造缺陷。但激光沉积修复过程伴随复杂的热力变化,很难进行试验检测研究,并且修复后零件存在变形开裂问题,零件表面及内部存在很大的残余应力,严重的影响激光沉积修复的零件修复质量,一但修复区开裂,产生修复废品,修复过程被迫终止。基于此,本文对激光沉积修复TA15钛合金温度场及应力场进行了研究,为控制激光沉积修复过程中残余应力及变形提供理论依据。本文采用ANSYS有限元分析软件,建立了激光沉积修复过程温度场及应力场的数学模型。采用单元生死技术实现对激光沉积修复TA15钛合金温度场的数值模拟,研究了激光功率、扫描速度等工艺参数以及不同基材大小和分区域扫描对激光沉积修复温度场的影响规律,分析了修复件内部节点的热循环特点以及温度梯度分布规律。在温度场模拟的基础上,采用热力耦合的方法,对应力场进行了数值模拟,分析了工艺参数及不同扫描方式及修复基体预先加热对激光沉积修复应力场的影响。搭建了激光沉积修复实验系统,采用红外测温仪对激光沉积修复过程温度场进行了实时动态跟踪测量,对激光沉积修复组织进行分析,最后对修复表面残余应力进行了测量。通过以上试验对模拟结果进行了验证,进一步完善了数学模型,为提高修复质量提供参考依据。
[Abstract]:Laser Deposition Repairing Technology) is a kind of advanced material augmentation technology which combines laser rapid prototyping technology with laser cladding technology. This technology can repair the damage and manufacturing defects of parts with any complex shape. However, the process of laser deposition repair is accompanied by complex thermal changes, so it is difficult to carry out experimental detection and research, and there are deformation and cracking problems in the parts after repair, and there are large residual stresses on the surface and inside of the parts. Seriously affect the repair quality of laser deposition repair parts, but the repair area cracks, resulting in repair scrap, the repair process has to be terminated. Based on this, the temperature field and stress field of TA15 titanium alloy repaired by laser deposition are studied, which provides a theoretical basis for controlling residual stress and deformation during laser deposition and repair. In this paper, the mathematical model of temperature field and stress field in laser deposition repair process is established by using ANSYS finite element analysis software. The numerical simulation of temperature field of laser deposition and repair of TA15 titanium alloy was carried out by using element birth and death technique. The influence of laser power, scanning speed and different substrate size and area scanning on the temperature field of laser deposition repair was studied. The characteristics of thermal cycling and the temperature gradient distribution of the joints are analyzed. Based on the simulation of temperature field, the thermal coupling method is used to simulate the stress field of laser deposition. The effects of process parameters, different scanning methods and pre-heating of repair matrix on the stress field of laser deposition repair are analyzed. The experimental system of laser deposition repair was set up. The temperature field of laser deposition repair process was measured by infrared thermometer, and the microstructure of laser deposition repair was analyzed. Finally, the residual stress of the surface was measured. The simulation results are verified by the above experiments, the mathematical model is further improved, and the reference is provided for improving the repair quality.
【学位授予单位】：沈阳航空航天大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG665

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