薄壁钛管剪应力本构参数识别方法

不同温度下的薄壁钛管剪应力本构参数识别，是研究薄壁钛管差温剪切弯曲过程管材塑性变形行为迫切需要解决的关键问题。提出了一种管材剪切测试的方法。将不同温度下薄壁钛管等温剪切测试、剪切测试过程模拟有限元模型、以及基于距离函数的响应面模型相结合，提出了薄壁钛管不同温度下剪应力本构参数逆向识别方法。采用该方法，识别了TA2薄壁钛管剪应力本构参数。同时建立了TA2薄壁钛管差温剪切弯曲过程模拟3维弹塑性热力耦合有限元模型。分别采用剪应力本构参数和单拉应力本构参数模拟弯管实验过程，评估了有限元模型的可靠性。结果表明：对于剪应力本构参数，温度越高，管材的K值和n值将减小，m值呈现波动的趋势。与单拉应力本构参数相比，剪应力本构参数对温度的变化更敏感，且剪应力本构参数值较小。与单拉应力本构参数相比，使用剪应力本构参数的有限元模型精度较高，模拟精度最大提高了60%。

Identification method of shear stress constitutive parameters of Ti-alloy thin-walled tube

The identification of shear stress constitutive parameters (SSCPs) of Ti-alloy thin-walled tubes (TATTs) at different temperature levels (DTLs) is a key problem for the research of plastic deformation behavior in these tube shear bending processes under differential temperature fields constraints (DTFCs). A tube shear test method is presented. The TATTs isothermal shear test processes under the DTLs, the finite element (FE) models for simulating these test processes and the response surface models based on distance functions have been combined to present a reverse method for identifying these SSCPs of the TATTs under the DTLs. Then, this method is used for identifying the SSCPs of TA2 TATTs. A 3D coupled thermal-mechanical elastic-plastic FE model for simulating these shear bending processes under DTFCs of the TA2 TATTs is established. An experimental bending process is simulated by this FE model using the SSCPs and the uniaixal tension stress constitutive parameters (UTSCPs) respectively, and the reliability of this FE model is estimated. The results reveal that for SSCPs, the larger the temperature, the smaller the values of K and n; the value of m fluctuates;the effects of temperature on the SSCPs are larger than the UTSCPs and the values of the SSCPs are smaller. The computational precision level of the FE model using the SSCPs is larger than the UTSCPs by 60%.