钨选区激光熔化应力场的数值模拟

建立了将随温度变化的材料参数特性和相变潜热考虑在内，用“生死单元”技术模拟铺粉过程的钨选区激光熔化热力耦合有限元模型，模拟了选区激光熔化过程中成形件的温度场和应力场，探究了不同基板预热温度和不同支撑结构对成形件残余应力的影响。模拟结果表明，金属钨在选区激光熔化过程中经历多次加热、冷却过程，温度分布不均匀。基板预热和施加支撑结构均能减小成形件的残余应力，当基板预热温度为1273.15K时，成形件中间节点残余应力减小118.99MPa，减小幅度为9.96%；当采用四层网格支撑结构时，成形件中间节点残余应力减小413.33MPa，减小幅度为34.61%。

Numerical Simulation on Stress Field of Selective Laser Melting Tungsten

A thermodynamic coupling finite element model of tungsten selective laser melting was established by using the ‘birth and death element’ technique to simulate the powder laying process, taking into account the material parameter characteristics and latent heat of phase transition. The temperature and stress fields of the forming parts during selective laser melting were simulated. The effects of different preheating temperatures of substrate and different support structures on the residual stress of formed parts was investigated. The simulation results show that tungsten has undergone many heating and cooling processes during selective laser melting, and the temperature distribution is not uniform. Both substrate preheating and applying support structures can reduce the residual stress of the formed part. When the preheating temperature of the substrate is 1273.15K, the residual stress of the intermediate joint of the forming part is reduced by 118.99MPa (9.96%). When the four-layer grid support structure is adopted, the residual stress of the middle joint of the forming part is reduced by 413.33MPa (34.61).