火焰筒局部蠕变屈曲分析方法

Local creep buckling analysis method of combustor liner

准确考虑火焰筒温度场和应力场的"局部"特性,提出"局部蠕变屈曲"概念,并给出一套局部蠕变屈曲分析方法.基于Hoff理论建立蠕变屈曲理论模型,结合理论和试验数据验证有限元方法处理蠕变屈曲问题的可行性.考虑蠕变屈曲失稳要素,结合静力结果确定蠕变屈曲危险部位,将子模型技术引入非线性/热弹塑性/蠕变有限元程序中,结合曲率极大点判据,确定危险部位蠕变屈曲临界时间.方法将改善传统方法中的平均温度、平均压应力和平面应变假设,提高了计算精度.

In consideration of the ＂local＂ feature of combustor liner temperature field and stress field, a concept of ＂local creep buckling＂ was presented in this paper along with an engineering analysis method. Firstly, the theoretical model of creep buckling was established based on Hoff theory. Secondly, the feasibility of using finite element method （FEM） to analyze creep buckling was validated by theoretical and test data. Thirdly, a statics analysis with thermal-mechanical loads was performed, and then the dangerous place of combustor liner local creep buckling was captured considering creep buckling instability factors. Finally, sub-model technique was used in nonlinear thermal elastic-plastic/creep finite element analysis to capture the critical time of local creep buckling with ＂curvature local maximum point＂ criterion. It could be concluded that, as compared with traditional method, the hypothesis of average temperature, average compressive stress and plane strain could be improved in this paper, thus the computational accuracy was enhanced greatly. The work of this paper is significant on the application of structure design of combustor liner.