梯度陶瓷喷嘴残余应力的有限元分析

Finite element simulation for residual stress of functionally gradient ceramic nozzle

为了提高喷嘴的抗冲蚀磨损能力,将梯度功能材料理论运用于喷嘴材料的设计中,改传统的均质喷嘴材料为非均质喷嘴材料,提出在梯度陶瓷喷嘴制备中将残余压应力引入喷嘴入口的设计目标.在组成分布指数一定的条件下,针对主要设计参数对梯度陶瓷喷嘴残余应力的影响进行有限元分析,探讨了梯度层厚度、临界梯度层材料组分差对SiC/(W,Ti)C单梯度陶瓷喷嘴残余热应力的影响规律,在组成分布指数取0.5时,优化SiC/(W,Ti)C梯度陶瓷喷嘴梯度层厚和临界梯度层材料组分差.结果表明,残余应力随梯度层厚h及临界梯度层SiC体积组分差的不同产生很大差异,合理设计梯度层厚h及临界梯度层SiC体积组分差可在喷嘴入口形成有效残余压应力,最佳梯度层厚为5mm,临界梯度层SiC组分差小于5%(体积分数).

The idea of functionally gradient material theory was used to improve the erosion wear resistance of the nozzles. The compressive residual stresses were introduced to the entry zone in the design of gradient ceramic nozzle. The effects of main parameter on the residual stress of the gradient nozzle were analyzed by finite element method. Effects of the layer thickness and the volume difference of SiC in various gradient layers of the SiC/（W,Ti）C on residual stresses were discussed. The optimum layer thickness and volume difference of SiC in various gradient layers of the SiC/（W,Ti）C were studied. Results showed that compressive residual stresses were appeared at the entry zone of the gradient nozzle. When the component distribution exponent is 0. 5, the optimum parameters of the layer thickness and the volume difference of SiC in various gradient layers of the SiC/（W,Ti）C gradient ceramic nozzle materials are 5 mm and 5 Vol. % respectively.