基于Cocks-Ashby模型的多轴蠕变设计准则的局限性及其修正

发布时间：2018-01-15 04:28

  本文关键词：基于Cocks-Ashby模型的多轴蠕变设计准则的局限性及其修正　出处：《机械工程学报》2017年16期 　论文类型：期刊论文

  更多相关文章： 黏塑性 多轴蠕变 Cocks-Ashby模型 简化模型修正

【摘要】：多轴应力状态下结构的蠕变变形分析是高温装备强度设计的理论基础。经典的Cocks-Ashby多轴蠕变孔洞长大模型及其简化模型存在着严苛的适用条件及局限性,仅适用于描述高温低应力环境下以晶间蠕变孔洞长大过程为材料蠕变损伤主要形式的蠕变变形行为。根据其简化解得到的用于单-多轴蠕变延性换算的多轴蠕变因子则存在着在低三轴应力度段给出的计算值较试验值偏小的问题。在基于WITCHMANN对该问题修正工作的基础上,通过合理的进一步优化,一个新的多轴蠕变因子被得出。将新修正因子应用在一个处于简化恒定应力场中的发动机热端叶片算例上,计算出恒载下叶片的等效多轴蠕变应变分布。有限元计算结果表明在叶片模型的叶根中部区域存在着较大的三轴应力度及较小的多轴蠕变因子,使得叶根中部原本应变不太明显的区域也产生了较大的等效多轴蠕变应变,导致叶片计算出的潜在失效面积较未经多轴蠕变因子修正前显著增加。
[Abstract]:The multiaxial stress state of the structure under the creep deformation analysis is the theoretical basis for high temperature equipment and strength design. Multi axial creep cavity classic Cocks-Ashby growth model and its simplified model is suitable for harsh conditions and limitations, only suitable for describing the creep deformation behavior at high temperature and low stress intergranular creep void growth process mainly in the form of material creep the damage of environment. According to the simplified solution for the multi axial creep factor single - multiaxial creep ductility conversion exists should be calculated intensity values given by the experimental value than some small question in the low three axis. Based on WITCHMANN on the issue of the rectification work, through further optimized, a new multiaxial creep factor was obtained. The new correction factor used in a simplified constant stress field in the engine hot end blade example, calculated under dead load of blade etc. Effect of multi axial creep strain distribution. The finite element calculation results show that in the central region of the blade root blade model has three axis should be multi axial creep strength and smaller factors larger, makes the leaf root central strain less obvious areas had also produced a multi axial creep strain larger equivalent, resulting in potential failure leaf area calculation that is without the multiaxial creep factor correction increased significantly.

【作者单位】： 华东理工大学承压系统与安全教育部重点实验室;
【基金】：国家自然科学基金资助项目(51325504,51475167)
【分类号】：O344.6
【正文快照】： 0前言1蠕变是高温设备中发生的一种依赖于温度、载荷和服役时间的时效塑性变形行为,属于黏塑性范畴。其产生机理和演化行为表现出强烈的温度和载荷相关性,需要合理的模型和函数方程去描述。例如,在中等温度和应力条件下,纯金属、合金等多晶体材料中发生的由位错攀移导致的蠕变，

本文编号：1426799