考虑应力集中和晶向的单晶叶片低周疲劳优化分析

LCF Optimization of Single Crystal Superalloy Blade Considering Stress Concentration and Crystallographic Orientation

关键词:  单晶  低周疲劳  应力集中  优化  滑移系  弹塑性本构  正交各向异性

Key words:  Single crystal  LCF  Stress concentration  Optimization  Slip system  Constitutive laws for elasticplastic  Orthotropic

摘要:

为评估单晶涡轮叶片低周疲劳寿命，提出了适用于单晶涡轮叶片的剪应力范围修正系数法。对单晶涡轮叶片进行了低周疲劳分析。采用剪应力范围修正系数法，克服了最大剪应力范围方法预测值偏高且无法考虑应力集中效应的缺点，其预测的低周疲劳寿命偏安全。基于有限变形晶体滑移理论、剪应力范围修正系数法和ANSYS有限元软件，建立了适用于镍基单晶涡轮叶片的低周疲劳分析及优化设计平台。对涡轮叶片进行了三维晶体取向相关性分析，通过对297个不同晶体取向的计算分析，预测的低周疲劳寿命最小值和最大值分别为328周和3861周。因此，通过控制晶体取向，可以在不增加重量(或不改变叶片结构)的基础上有效延长叶片低周疲劳寿命。

Abstract:

In order to evaluate the low cycle fatigue life of single crystal turbine blade，a shear stress range amendatory coefficient method suitable for single crystal turbine blade was proposed. LCF analysis to a single crystal turbine blade was conducted. By adopting the shear stress range amendatory coefficient method，which overcomes the shortcoming that predicted value is higher and could not consider the stress concentration effect when using the maximum shear stress range method，and the predicted LCF life is security. Based on finite deformation crystal sliding theory，shear stress range amendatory coefficient method and the finite software ANSYS，a low cycle fatigue analysis and optimization design platform suitable for nickel based single crystal turbine blade was proposed. Three dimensional crystallographic orientation correlation analysis of turbine blade was carried out，through calculation and analysis of 297 different crystal orientations，the minimum and maximum value of predicted LCF life was 328 and 3861 cycles individually. So through controlling the crystal orientation，it could effectively extend blade’s LCF life on the basis of no weight increment or blade structure changing.