镍基单晶结构的蠕变损伤寿命研究

FEM creep damage study for nickel-base single crystal structure under multiaxial stress conditions

关键词:  蠕变分析  损伤容限  寿命试验  镍基合金  单晶  涡轮叶片

Key words:  Creep analysis  Damage tolerance  Life test  Nickel base superalloy  Single crystal  Turbine blade

摘要:

基于镍基单晶合金材质细观演化规律,提出了同时考虑筏化 解筏及夹杂空洞损伤机理的双参数蠕变损伤本构模型。该本构模型已编入ABAQUS的umat。单向应力状态试验表明它可以模拟镍基单晶结构材料的蠕变规律,特别是晶体取向相关性;利用双剪切和模拟单晶叶片蠕变试验对模型进行了考核,结果相当满意。进一步对单晶叶片的蠕变损伤寿命进行分析,叶片的三维取向优化,可以很大程度地提高叶片的蠕变寿命。

Abstract:

Based on the microstructural assessment, a two-state-variable crystallographic creep damage constitutive equation was presented for nickel-base single crystal superalloys, which takes into consideration of the rafting-derafting and the damage of the voids simultaneously. The constitutive equation was programmed as a user subroutine umat into the ABAQUS. With the uniaxial creep experimental data, the constitutive equation can model the creep damage behavior of nickel-base single crystal superalloys, especially the dependence of the creep anisotropy on the crystallographic orientation. The double shear specimens and modeling blades were studied experimentally to validate the constitutive equation. The results of the validation are satisfactory. The damage and life behaviors of a turbine blades were presented as an example of the application. The influence of the crystallographic orientations on the blade lives was analyzed specially for the optimization of blade crystallographic orientations. The optimization of the crystallographic orientations will find a maximum-life orientation.