本文選題：起重機 + 桁架臂　； 參考：《大連理工大學》2014年博士論文

【摘要】：桁架臂起重機是廣泛應(yīng)用于國民經(jīng)濟各領(lǐng)域的一種起重設(shè)備,桁架臂是起重機關(guān)鍵承載部件。如何有效地對臂架壽命和可靠性進行預(yù)測,是起重機疲勞研究領(lǐng)域備受關(guān)注的一個重要課題。目前國內(nèi)的研究缺乏專門針對起重機典型工況下的桁架臂疲勞壽命S-N曲線；采用比較常用的線性累積損傷理論對疲勞壽命進行計算所得到的結(jié)果精度不高,其他非線性累積損傷理論由于需要大量試驗數(shù)據(jù)擬合,公式復(fù)雜,工程適用性不強。針對上述問題,本文主要開展了如下研究工作： (1)利用雙曲正弦函數(shù)與斷裂力學裂紋擴展曲線相似性理論,提出在常幅應(yīng)變-壽命公式Basquin-Manson-Coffin(BMC)公式的基礎(chǔ)上,提出了累積損傷比例因子概念,建立了單位裂紋擴展速率與壽命的歸一化約束關(guān)系。根據(jù)起重機應(yīng)力特性,提出了基于模糊損傷的改進型非線性累積損傷模型和概率模型,通過比較疲勞壽命影響的各個因素,得到了各個參數(shù)的基本敏感度趨勢。 (2)針對起重機獲取實際應(yīng)力譜比較困難的現(xiàn)狀,提出了基于虛擬樣機技術(shù)的“實測+仿真+比對+統(tǒng)計”組合策略的危險點確定和應(yīng)力譜獲取方法。通過建立起重機整體和局部危險區(qū)域細化的耦合有限元虛擬樣機,實現(xiàn)了用動力學仿真手段獲取了應(yīng)力譜,為起重機的應(yīng)力譜獲取提供了新的途徑。 (3)對影響起重機桁架臂可靠性的七個體系單因素及其評價指標進行了分析,建立了多層次構(gòu)權(quán)與動態(tài)構(gòu)權(quán)相結(jié)合的臂架整體可靠性評估體系框架,并基于此提出了疲勞剩余壽命可靠度與臂架整體可靠度的安全決策措施。設(shè)計了基于Elman神經(jīng)網(wǎng)絡(luò)的臂架整體可靠度預(yù)測模型,可根據(jù)大量專家數(shù)據(jù)的訓練,自動計算可靠度,方便工程應(yīng)用。 (4)基于熱點應(yīng)力法,對起重機桁架臂K節(jié)點的疲勞試驗方法進行了研究,確定了起重機典型工況下的較優(yōu)工裝設(shè)計,獲取了起重機典型載荷下的桁架臂K節(jié)點S-N曲線,對影響疲勞壽命的應(yīng)變歷程、平均應(yīng)力和初始損傷三個主要因素進行了試驗,通過數(shù)據(jù)擬合得到了概率BMC公式的材料參數(shù),為起重機抗疲勞設(shè)計的工程應(yīng)用提供了數(shù)據(jù)參考。 (5)開發(fā)了面向起重機桁架臂的疲勞壽命與可靠性評估系統(tǒng),能夠?qū)崿F(xiàn)起重機載荷記錄、壽命計算、安全決策等功能。通過案例分析,探討了起重機理論計算結(jié)果與實際檢測的符合性。
[Abstract]:Truss jib crane is a kind of lifting equipment which is widely used in various fields of national economy. Truss jib is the key bearing part of crane. How to effectively predict the life and reliability of boom is an important subject in the field of crane fatigue research. At present, there is a lack of S-N curve for the fatigue life of truss arm under typical conditions of crane, and the accuracy of fatigue life calculated by linear cumulative damage theory is not high. Other nonlinear cumulative damage theories require a large number of experimental data to fit, the formulas are complex, and the engineering applicability is not strong. In view of the above problems, this paper mainly carried out the following research work: 1) based on the similarity theory of hyperbolic sinusoidal function and crack growth curve in fracture mechanics, the concept of cumulative damage proportional factor is proposed based on the constant amplitude strain-life formula Basquin-Manson-Coffin BMCs. The normalized constraint relationship between unit crack growth rate and life is established. According to the stress characteristics of crane, an improved nonlinear cumulative damage model and a probabilistic model based on fuzzy damage are proposed. By comparing various factors affecting fatigue life, the basic sensitivity trend of each parameter is obtained. 2) aiming at the difficult situation of obtaining actual stress spectrum of crane, a method of determining the dangerous point and obtaining stress spectrum of the combination strategy of "measured simulation comparison and statistics" based on virtual prototyping technology is put forward. By establishing the coupled finite element virtual prototype of the whole and local dangerous areas of crane, the dynamic simulation method is used to obtain the stress spectrum, which provides a new way to obtain the stress spectrum of the crane. In this paper, the single factor of seven system and its evaluation index which affect the reliability of crane truss arm are analyzed, and the frame of the whole reliability evaluation system of jib is established, which combines multi-level construction weight and dynamic construction weight. Based on this, the safety decision measures of fatigue residual life reliability and overall reliability of boom are put forward. An integral reliability prediction model based on Elman neural network is designed, which can automatically calculate reliability according to a large number of expert data, and is convenient for engineering application. 4) based on the hot spot stress method, the fatigue test method of K-joint of crane truss arm is studied, and the optimum tooling design under typical condition of crane is determined, and the S-N curve of K-node of truss arm under typical load of crane is obtained. Three main factors affecting the fatigue life, such as strain history, average stress and initial damage, are tested. The material parameters of the probabilistic BMC formula are obtained by fitting the data, which provides a data reference for the engineering application of anti-fatigue design of cranes. The fatigue life and reliability evaluation system for crane truss arm is developed, which can realize the functions of crane load record, life calculation, safety decision and so on. Through the case analysis, the conformance between the calculation results of crane theory and the actual inspection is discussed.
【學位授予單位】：大連理工大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TH21

【參考文獻】

相關(guān)期刊論文 前10條

1 賈星蘭,劉文s，

本文編號：1938526