304不锈钢和42CrMo钢在棘轮—疲劳交互作用下的损伤演化研究

发布时间：2018-05-17 10:40

本文选题：棘轮效应 + 疲劳　；参考：《西南交通大学》2017年硕士论文

【摘要】：材料和构件在循环过程中的损伤一直是工程中广受学者和研究人员关心的热点问题。研究材料的损伤行为,首要的问题是选择合适的损伤变量来表征和描述材料的损伤状态。近年来国内外学者对于单调拉伸、应变控制低周疲劳循环、应力控制高周疲劳循环过程中疲劳损伤演化的研究已有较多的研究,但对于非对称应力控制棘轮-疲劳交互作用循环过程中的损伤研究还很少见。本文针对循环硬化的304不锈钢、循环稳定的退火42CrMo钢和循环软化的调质42CrMo钢进行了非对称应力循环下棘轮-疲劳交互作用过程中的损伤演化研究。本文主要开展了如下工作:1.用弹性模量的变化来定义损伤变量,研究了三种循环特性材料(循环硬化、循环稳定、循环软化)在单轴棘轮-疲劳交互作用下的损伤演化特征,揭示了平均应力、应力幅值对损伤的影响。2.从轴向弹性模量变化角度讨论了 304不锈钢、退火42CrMo钢以及调质42CrMo钢在非比例多轴加载路径下的棘轮-疲劳交互作用过程中的损伤演化特征,分析了非比例多轴加载下加载路径、应力幅和平均应力等因素对不同循坏特性材料损伤的影响。3.根据三种循环特性材料在单轴非对称加载下的损伤演化特点,基于棘轮损伤和疲劳损伤的叠加,提出了一种考虑棘轮-疲劳交互作用的损伤演化模型。该模型能较好的反映平均应力对损伤的影响,也能体现疲劳失效和棘轮失效损伤临界值的不同。该模型形式简单,变量易测,引入应变寿命曲线来预估疲劳寿命,避免了传统疲劳损伤模型需要准确知道实际疲劳寿命的不足,便于工程应用。
[Abstract]:The damage of materials and components in the cyclic process has been a hot issue which is widely concerned by scholars and researchers in engineering. The most important problem in studying the damage behavior of materials is to select appropriate damage variables to characterize and describe the damage state of materials. In recent years, scholars at home and abroad have studied the fatigue damage evolution in the process of monotone stretching, strain controlling low cycle fatigue cycle and stress controlling high cycle fatigue cycle. However, it is rare to study the damage in the cyclic process of asymmetric stress controlled ratcheting and fatigue interaction. In this paper, the damage evolution of cyclic hardening 304 stainless steel, cyclic stable annealed 42CrMo steel and cyclic softening quenched and tempered 42CrMo steel during ratcheting and fatigue interaction under asymmetric stress cycling is studied. The main work of this paper is as follows: 1. The damage variable is defined by the variation of elastic modulus. The damage evolution characteristics of three cyclic materials (cyclic hardening, cyclic stability, cyclic softening) under uniaxial ratchet fatigue interaction are studied, and the average stress is revealed. The effect of stress amplitude on damage. The damage evolution characteristics of 304 stainless steel, annealed 42CrMo steel and quenched and tempered 42CrMo steel during ratcheting and fatigue interaction under non-proportional multiaxial loading paths are discussed from the angle of axial elastic modulus variation. The effects of non-proportional multiaxial loading path, stress amplitude and average stress on the damage of materials with different failure characteristics are analyzed. According to the damage evolution characteristics of three cyclic materials under uniaxial asymmetric loading and based on the superposition of ratchet damage and fatigue damage, a damage evolution model considering ratchet and fatigue interaction is proposed. The model can reflect the effect of average stress on damage and the critical value of fatigue failure and ratchet failure. The model is simple in form and easy to measure variables. The strain life curve is introduced to predict the fatigue life. It avoids the deficiency of the traditional fatigue damage model which needs to know the actual fatigue life accurately and is convenient for engineering application.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG142.1

【共引文献】