發(fā)布時間：2018-05-17 10:40

  本文選題：棘輪效應(yīng) + 疲勞　； 參考：《西南交通大學》2017年碩士論文

【摘要】：材料和構(gòu)件在循環(huán)過程中的損傷一直是工程中廣受學者和研究人員關(guān)心的熱點問題。研究材料的損傷行為,首要的問題是選擇合適的損傷變量來表征和描述材料的損傷狀態(tài)。近年來國內(nèi)外學者對于單調(diào)拉伸、應(yīng)變控制低周疲勞循環(huán)、應(yīng)力控制高周疲勞循環(huán)過程中疲勞損傷演化的研究已有較多的研究,但對于非對稱應(yīng)力控制棘輪-疲勞交互作用循環(huán)過程中的損傷研究還很少見。本文針對循環(huán)硬化的304不銹鋼、循環(huán)穩(wěn)定的退火42CrMo鋼和循環(huán)軟化的調(diào)質(zhì)42CrMo鋼進行了非對稱應(yīng)力循環(huán)下棘輪-疲勞交互作用過程中的損傷演化研究。本文主要開展了如下工作:1.用彈性模量的變化來定義損傷變量,研究了三種循環(huán)特性材料(循環(huán)硬化、循環(huán)穩(wěn)定、循環(huán)軟化)在單軸棘輪-疲勞交互作用下的損傷演化特征,揭示了平均應(yīng)力、應(yīng)力幅值對損傷的影響。2.從軸向彈性模量變化角度討論了 304不銹鋼、退火42CrMo鋼以及調(diào)質(zhì)42CrMo鋼在非比例多軸加載路徑下的棘輪-疲勞交互作用過程中的損傷演化特征,分析了非比例多軸加載下加載路徑、應(yīng)力幅和平均應(yīng)力等因素對不同循壞特性材料損傷的影響。3.根據(jù)三種循環(huán)特性材料在單軸非對稱加載下的損傷演化特點,基于棘輪損傷和疲勞損傷的疊加,提出了一種考慮棘輪-疲勞交互作用的損傷演化模型。該模型能較好的反映平均應(yīng)力對損傷的影響,也能體現(xiàn)疲勞失效和棘輪失效損傷臨界值的不同。該模型形式簡單,變量易測,引入應(yīng)變壽命曲線來預(yù)估疲勞壽命,避免了傳統(tǒng)疲勞損傷模型需要準確知道實際疲勞壽命的不足,便于工程應(yīng)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.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG142.1

【共引文獻】

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6 郭桂林;高速受電弓控制系統(tǒng)研究[D];西南交通大學;2014年

7 林澤峰;弓網(wǎng)系統(tǒng)氣動彈性響應(yīng)研究[D];西南交通大學;2017年

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本文編號：1901058