激光烧结Al2O3/Ti系FGM的温度场与热应力场

用有限元法对激光烧结Al2O3/Ti系FGM的温度场和残余热应力场进行了模拟计算,并对烧结过程试样中的温度分布进行了实时测量.结果表明:激光照射面(Al2O3层)和背光面(Ti层)的温度落差为325℃.陶瓷侧温度梯度大于金属侧,成分梯度指数p值愈大,陶瓷侧温度梯度愈大.试样内残余热应力分布受p值控制,依据残余热应力最小且陶瓷层为压应力的设计准则,确定了激光烧结Al2O3/Ti系FGM的最佳成分梯度指数p=0.5.

Analysis on the field of temperature and thermal stress for Al2O3/Ti system FGM during laser sintering

We use finite element method to calculate temperature field and thermal stress field for Al₂O₃/Ti system FGM in the process of laser sintering.The temperature of the different layers of the sintering sample was measured with the thermocouples.The results show that the temperature drop between the laser irradiating surface(Al₂O₃/Ti layer) and the back surface(Ti layer) was 325℃,and the temperature gradient was more precipitous in Al₂O₃ ceramic layer than in Ti metal layer.We defined the parameter p,called component gradient of FGM sample,to indicate the level of the temperature gradient in ceramic Al₂O₃ layer.The thermal residual stress distribution mainly was dependent on the value of p.The axial shear stress occurred near the radial free edge,and transformed from compressive stress to tensile stress along with the increasing of p from less than 0.5 to greater than 0.5.The maximum radial stress occurred in the transition region between pure Al₂O₃ layer and graded interlayer.The distribution of circumferential stress was similar to radial stress distribution.All of the component of the thermal residual stress got the minimum when p=0.5.