【摘要】：疲勞破壞是機(jī)械結(jié)構(gòu)件失效的主要形式,結(jié)構(gòu)件在受到循環(huán)載荷的作用下可能會(huì)發(fā)生疲勞甚至破壞。采用不同的疲勞分析方法,可對(duì)結(jié)構(gòu)件疲勞損傷的特點(diǎn)進(jìn)行分析。在實(shí)際工況下,結(jié)構(gòu)件承受的載荷和工作環(huán)境十分復(fù)雜,并且機(jī)械結(jié)構(gòu)件疲勞的發(fā)生存在很多隨機(jī)性。因此,從數(shù)理統(tǒng)計(jì)的角度提出疲勞統(tǒng)計(jì)學(xué)分析方法,有望對(duì)機(jī)械結(jié)構(gòu)件疲勞損傷進(jìn)行有效評(píng)估。本文以機(jī)械結(jié)構(gòu)疲勞狀態(tài)為研究對(duì)象,根據(jù)結(jié)構(gòu)件的材料特性和受載情況,采用數(shù)理統(tǒng)計(jì)方法對(duì)機(jī)械結(jié)構(gòu)承載件的疲勞狀態(tài)進(jìn)行統(tǒng)計(jì)學(xué)分析。構(gòu)建與結(jié)構(gòu)件材料性質(zhì)相一致的小構(gòu)件疲勞試驗(yàn)裝置,確定了四種不同的試驗(yàn)條件;利用有限元方法分析了試件的應(yīng)力、應(yīng)變,確定了結(jié)構(gòu)件在受力情況下的易損傷部位,為合理布置光纖光柵傳感器提供了依據(jù)。在傳統(tǒng)的疲勞分析方法的基礎(chǔ)上,分析了機(jī)械結(jié)構(gòu)疲勞的影響因素,提出了機(jī)械結(jié)構(gòu)件疲勞損傷的統(tǒng)計(jì)學(xué)分析方法。針對(duì)結(jié)構(gòu)件所受載荷的特征,研究了試件在受力情況下應(yīng)力、應(yīng)變數(shù)據(jù)的變化規(guī)律,并且對(duì)試驗(yàn)數(shù)據(jù)進(jìn)行均值處理。根據(jù)統(tǒng)計(jì)學(xué)疲勞損傷分析方法,對(duì)等價(jià)彈性模量試驗(yàn)數(shù)據(jù)進(jìn)行線性回歸分析和統(tǒng)計(jì)。結(jié)果表明,等價(jià)彈性模量的試驗(yàn)數(shù)據(jù)與試件的實(shí)際工作情況擬合比較好。采用假設(shè)檢驗(yàn),對(duì)試驗(yàn)數(shù)據(jù)進(jìn)行了穩(wěn)定性分析。當(dāng)結(jié)構(gòu)件出現(xiàn)疲勞時(shí),等價(jià)彈性模量試驗(yàn)數(shù)據(jù)的總體均值檢驗(yàn)顯著。結(jié)果表明,當(dāng)應(yīng)力、應(yīng)變和等價(jià)彈性模量在頻率較高和振幅較大的情況下,結(jié)構(gòu)件在較短試驗(yàn)時(shí)間發(fā)生疲勞而且疲勞速率變化比較大。通過對(duì)等價(jià)彈性模量數(shù)據(jù)的統(tǒng)計(jì)分析,獲得了試件疲勞損傷與等價(jià)彈性模量的關(guān)系,確定了試件發(fā)生疲勞的時(shí)間點(diǎn)以及載荷的幅值和頻率對(duì)疲勞的影響程度,并歸納出在不同試驗(yàn)條件下試件疲勞狀態(tài)的變化規(guī)律。本文對(duì)機(jī)械結(jié)構(gòu)件在不同試驗(yàn)條件下的應(yīng)力、應(yīng)變、等價(jià)彈性模量試驗(yàn)數(shù)據(jù)進(jìn)行了分析,研究了彈性模量和結(jié)構(gòu)件疲勞狀態(tài)的關(guān)系,提出了一種評(píng)估機(jī)械結(jié)構(gòu)件疲勞狀態(tài)的統(tǒng)計(jì)學(xué)方法。研究結(jié)果可為機(jī)械結(jié)構(gòu)件的疲勞分析提供理論和試驗(yàn)依據(jù)。
[Abstract]:Fatigue failure is the main form of failure of mechanical structural parts. Fatigue and even failure of structural parts may occur under cyclic load. Different fatigue analysis methods can be used to analyze the fatigue damage characteristics of structural parts. Under the actual working conditions, the load and working environment of structural parts are very complex, and there are many randomness of fatigue occurrence of mechanical structural parts. Therefore, from the point of view of mathematical statistics, the fatigue statistical analysis method is proposed, which is expected to effectively evaluate the fatigue damage of mechanical structural parts. In this paper, the fatigue state of mechanical structure is studied. According to the material characteristics and loading conditions of structural parts, the fatigue state of mechanical structural load-bearing parts is analyzed statistically by means of mathematical statistics. In this paper, a fatigue test device for small components is constructed, which is consistent with the material properties of structural parts, and four different test conditions are determined, and the stress and strain of the specimens are analyzed by using finite element method, and the vulnerable sites of structural members under stress are determined. It provides a basis for the reasonable arrangement of fiber Bragg grating sensors. On the basis of the traditional fatigue analysis method, the influencing factors of fatigue of mechanical structure are analyzed, and the statistical analysis method of fatigue damage of mechanical structural parts is put forward. According to the characteristics of the load on the structural parts, the variation law of the stress and strain data is studied, and the mean value of the test data is processed. According to the statistical fatigue damage analysis method, the test data of equivalent elastic modulus are analyzed by linear regression analysis and statistics. The results show that the experimental data of equivalent elastic modulus fit well with the actual working conditions of the specimen. The stability of the test data is analyzed by using hypothesis test. When fatigue occurs, the test results of equivalent modulus of elasticity are significant. The results show that when the stress, strain and equivalent elastic modulus are higher in frequency and amplitude, the fatigue and fatigue rate of the structural parts change greatly in a short test time. Based on the statistical analysis of the equivalent elastic modulus data, the relationship between fatigue damage and equivalent elastic modulus of the specimen is obtained, and the time point when fatigue occurs and the influence of the amplitude and frequency of load on fatigue are determined. The changes of fatigue state of specimens under different test conditions are also summarized. In this paper, the experimental data of stress, strain and equivalent elastic modulus of mechanical structural parts under different test conditions are analyzed, and the relationship between elastic modulus and fatigue state of structural parts is studied. A statistical method for evaluating fatigue state of mechanical structures is presented. The results can provide theoretical and experimental basis for fatigue analysis of mechanical structural parts.
【學(xué)位授予單位】：河南科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TH114

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本文編號(hào)：2213526