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基于疲勞理論和能量分析的機械設(shè)備壽命預(yù)測方法研究

發(fā)布時間:2018-03-08 04:16

  本文選題:狀態(tài)監(jiān)測 切入點:振動能量 出處:《鄭州大學(xué)》2013年碩士論文 論文類型:學(xué)位論文


【摘要】:近年來,科技的進步正帶動著現(xiàn)代機械設(shè)備向大型化、精密化、復(fù)雜化、連續(xù)化、高速化的方向發(fā)展,而工作環(huán)境越來越復(fù)雜的機械零件和工程構(gòu)件,也同樣受到長期、持續(xù)的交變載荷的作用。交變載荷容易造成機械設(shè)備的疲勞問題,疲勞破壞是在工程中造成構(gòu)件失效最重要的原因之一。因此,無論是工程實際還是在理論研究上,疲勞學(xué)都是研究的熱點問題。早在19世紀(jì),疲勞問題開始進入世界各地學(xué)者們研究的領(lǐng)域,且在很長一段時間內(nèi),取得了很多豐碩的成果。雖然如此,壽命預(yù)測依然面臨諸多問題。如果用一種確定性的方法去預(yù)測,所得的疲勞壽命都是一個確定的值,但結(jié)構(gòu)的疲勞是一種非常復(fù)雜的現(xiàn)象,它受到諸多不確定因素的影響。現(xiàn)有的預(yù)測理論主要分為基于力學(xué)的壽命預(yù)測和基于概率統(tǒng)計的壽命預(yù)測理論,這些理論是基于構(gòu)件的應(yīng)力幅值和平均應(yīng)力值等靜態(tài)特征值進行估算,忽略了系統(tǒng)的動態(tài)變化,造成估算誤差,而狀態(tài)監(jiān)測能夠得到系統(tǒng)的動態(tài)參數(shù);谝陨峡紤],將傳統(tǒng)的疲勞理論和系統(tǒng)動態(tài)狀態(tài)監(jiān)測這種信息技術(shù)聯(lián)系起來進行機械設(shè)備的壽命預(yù)測是非常必要的。 本文首先通過求解一個單自由度振動系統(tǒng)在簡諧激勵作用下的響應(yīng)來引入振動能量,闡述振動能量的基本概念和意義,以及在壽命預(yù)測中的可行性分析,結(jié)合疲勞理論,推導(dǎo)出基于振動能量的疲勞壽命公式,最后使用健康度的概念,對機械設(shè)備的剩余壽命進行預(yù)測。本文的主要內(nèi)容如下所示: 1.對一單自由度系統(tǒng)進行在簡諧激勵作用下的振動分析,從中得到單頻率的振動功率和振動能量,判斷兩個特征量是否能全面的反應(yīng)系統(tǒng)信息,并揭示振動能量與疲勞壽命的關(guān)系。最后根據(jù)傳統(tǒng)的譜估計方法,得到振動能量譜的表達(dá)式。 2.對振動能量譜在狀態(tài)監(jiān)測和故障診斷中的作用進行分析研究,利用振動能量譜能夠全面反應(yīng)系統(tǒng)信息的優(yōu)勢,并結(jié)合全矢譜進行雙通道的信息融合,得到全矢振動能量譜,對轉(zhuǎn)子系統(tǒng)進行故障診斷,能有效的解決轉(zhuǎn)子故障診斷中的誤診和漏診狀況,更加準(zhǔn)確有效的識別轉(zhuǎn)子故障。 3.分別通過理論和實例證明疲勞壽命在外部激勵不變的情況下與振動能量的近似線性關(guān)系,并探討疲勞壽命與激振頻率和應(yīng)力之間的關(guān)系,說明振動能量能夠全面反應(yīng)系統(tǒng)信息,可用于疲勞壽命預(yù)測。 4.結(jié)合疲勞壽命預(yù)測中的線性累計損傷理論,利用時間歷程下的瞬時振動能量的改變和振動能量的累計,推導(dǎo)疲勞壽命預(yù)測公式,并畫出振動能量一時間的疲勞壽命曲線,通過仿真分析驗證。 5.結(jié)合疲勞壽命中健康度的概念,提出能量健康度概念。通過同等激勵下瞬時能量得到健康度指數(shù),并求出剩余振動能量,再根據(jù)振動能量一時間曲線,得到系統(tǒng)的剩余壽命。
[Abstract]:In recent years, the progress of science and technology is driving the development of modern machinery and equipment towards the direction of large-scale, precision, complexity, continuity and high speed, while the more and more complex working environment of mechanical parts and engineering components, also suffered a long period of time. The function of continuous alternating load. The fatigue problem of mechanical equipment is easy to be caused by alternating load. Fatigue failure is one of the most important causes of component failure in engineering. As early as 19th century, fatigue began to enter the research field of scholars all over the world, and in a long time, a lot of achievements have been made. Life prediction still faces many problems. If a deterministic method is used to predict the fatigue life, the obtained fatigue life is a certain value, but the fatigue of the structure is a very complicated phenomenon. It is influenced by many uncertain factors. The existing prediction theories are mainly based on mechanics and probability statistics. These theories are based on the static eigenvalues such as the stress amplitude and the average stress value of the component, ignoring the dynamic changes of the system, resulting in the estimation error, and the dynamic parameters of the system can be obtained by state monitoring. It is necessary to combine the traditional fatigue theory with the information technology of system dynamic state monitoring to predict the life of mechanical equipment. In this paper, the vibration energy is introduced by solving the response of a single degree of freedom vibration system under simple harmonic excitation, and the basic concept and significance of vibration energy are expounded, as well as the feasibility analysis in life prediction, combined with fatigue theory. The formula of fatigue life based on vibration energy is derived. Finally, the residual life of mechanical equipment is predicted by using the concept of health. The main contents of this paper are as follows:. 1. The vibration analysis of a single degree of freedom system under simple harmonic excitation is carried out, from which the vibration power and vibration energy of a single frequency are obtained. The relationship between vibration energy and fatigue life is revealed. Finally, the expression of vibration energy spectrum is obtained according to the traditional spectrum estimation method. 2. The function of vibration energy spectrum in state monitoring and fault diagnosis is analyzed and studied. By using vibration energy spectrum, the system information can be fully reflected, and the whole vector energy spectrum can be obtained by combining the full vector spectrum with dual channel information fusion. The fault diagnosis of rotor system can effectively solve the misdiagnosis and missed diagnosis in rotor fault diagnosis and identify rotor fault more accurately and effectively. 3. The approximate linear relationship between fatigue life and vibration energy under constant external excitation is proved by theoretical and practical examples, and the relationship between fatigue life and exciting frequency and stress is discussed. The results show that the vibration energy can fully reflect the system information and can be used to predict the fatigue life. 4. Combining with the linear cumulative damage theory in fatigue life prediction, using the change of instantaneous vibration energy and the accumulation of vibration energy under the time course, the fatigue life prediction formula is derived, and the fatigue life curve of vibration energy and time is drawn. It is verified by simulation analysis. 5. Combining the concept of health degree in fatigue life, the concept of energy health degree is put forward. The index of health degree is obtained by instantaneous energy under the same excitation, and the residual vibration energy is obtained, and then the residual life of the system is obtained according to the time-curve of vibration energy.
【學(xué)位授予單位】:鄭州大學(xué)
【學(xué)位級別】:碩士
【學(xué)位授予年份】:2013
【分類號】:TH114

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