TC17钛合金激光喷丸应力场及支持向量机应力热松弛模型

对TC17钛合金进行了不同功率密度下激光喷丸强化,使用X射线衍射仪测试了激光喷丸冲击波诱导的残余压应力场的分布,测试了不同温度真空保温下残余压应力的热松弛规律,最后基于支持向量机理论建立了残余压应力热松弛预测模型,并用试验结果对模型进行验证.研究表明:TC17钛合金在功率密度为4GW/cm²时表层残余压应力场最佳;残余压应力在280℃和450℃真空保温150min后分别有11.24%和27.11%的松弛;在280℃和450℃交替保温160min后应力松弛33.9%;残余压应力在试验温度保温160min后有大部分剩余,可以有效提高TC17钛合金抗疲劳性能、基于支持向量机的预测模型能够较精确的表征TC17钛合金的应力松弛规律,满足工程使用要求,对其他材料表层残余压应力热松弛分析具有借鉴意义.

Residual stress of laser peening processed TC17 and stress relax prediction model based on support vector machines theory

TC17 titanium alloy was laser peening(LP) processed by different power densities.X-ray diffraction method was used to measure the residual stress induced by LP.Vacuum thermal retardation at 280 ℃ and 450 ℃ for 160 min was used to study the residual stress relaxation regularity.The prediction model was based on support vector machines(SVM) theory and the model was verified by experimental results at last.The results show that 4 GW/cm2 is the optimal power density to process TC17 titanium alloy.The thermal relaxation is about 11.24%,27.11% at 280 ℃ and 450 ℃ for 150 min respectively.And relaxation enhances to 33.9% after 280 ℃ and 450 ℃ alternate vacuum thermal retardation.The relaxation indicates that the majority of residual stress is preserved,and thus improves the fatigue resistance of titanium alloy.The residual stress prediction model can characterize the relaxation regularity accurately.And the model is useful to analyze the residual stress thermal relaxation of other metals.