【摘要】：焊接結(jié)構(gòu)在機械工程、車輛船舶、海洋工程、石油化工等領(lǐng)域應(yīng)用廣泛,其中一些重要結(jié)構(gòu)件在工作中承受復(fù)雜隨機載荷,疲勞破壞是其主要失效形式之一。應(yīng)用概率統(tǒng)計理論與方法,研究結(jié)構(gòu)疲勞壽命的概率屬性,更加客觀、真實地預(yù)測結(jié)構(gòu)疲勞壽命和可靠性,有重要工程應(yīng)用價值。本論文以焊接結(jié)構(gòu)疲勞概率壽命預(yù)測為背景,主要研究內(nèi)容如下：(1)針對高鐵車體焊接結(jié)構(gòu)件進行實驗室條件下的疲勞壽命測試及應(yīng)力分析。根據(jù)車體結(jié)構(gòu)特點,設(shè)計了兩組(每組兩種)疲勞壽命測試對比試樣。對每組試驗,分別采用相對簡單的軸向拉伸加載試樣和較復(fù)雜的彎曲加載試樣及相應(yīng)的疲勞試驗方法,獲得兩種不同形式的試件在不同加載方式下的疲勞試驗數(shù)據(jù)。同時,應(yīng)用有限元方法建立對應(yīng)于兩種加載方式的結(jié)構(gòu)試件的靜力學模型,計算出各自危險點的應(yīng)力。通過對比兩種結(jié)構(gòu)試件的試驗壽命數(shù)據(jù)、斷裂位置以及有限元仿真得出的應(yīng)力分布情況,探討了利用簡單的拉伸疲勞試驗來代替復(fù)雜的彎曲疲勞試驗的可行性。此外,還分析了平均應(yīng)力影響及修正問題。(2)分析、比較不同的疲勞試驗數(shù)據(jù)信息提取方法與效果�；谠囼灁�(shù)據(jù),利用概率統(tǒng)計分析方法,對忽略截尾數(shù)據(jù)的壽命數(shù)據(jù)進行統(tǒng)計分析,擬合出壽命數(shù)據(jù)的分布類型和P-S-N曲線；應(yīng)用極大似然法和K-S檢驗法,對含截尾數(shù)據(jù)的壽命數(shù)據(jù)進行參數(shù)估計。對兩種處理結(jié)果的分析、比較表明,針對不同類型的試驗數(shù)據(jù),應(yīng)充分考慮截尾數(shù)據(jù)的影響,選擇合理的處理方法,截尾數(shù)據(jù)通常不應(yīng)忽略。由此可見,傳統(tǒng)疲勞壽命試驗數(shù)據(jù)處理過程中,簡單忽略截尾數(shù)據(jù)(包括壽命溢出數(shù)據(jù)和非標距段斷裂的試樣的壽命數(shù)據(jù))的做法,會在不同程度上低估試驗對象的疲勞性能。(3)以液壓支架(大型焊接結(jié)構(gòu))為背景,利用有限元軟件計算液壓支架整架在不同工況下的應(yīng)力分布,同時通過實際結(jié)構(gòu)測試獲得相應(yīng)工況測試點的真實應(yīng)力值,有限元分析與實測結(jié)果相互印證,確定了支架的危險部位；利用液壓支架與采場圍巖的相互作用機理,詳細研究液壓支架在井下工程過程中的載荷歷程,通過Monte Carlo數(shù)值仿真方法,編制出了能反映載荷復(fù)雜性與隨機性特征的載荷譜,進而應(yīng)用局部應(yīng)力應(yīng)變法和Miner累積損傷理論對液壓支架的使用壽命進行預(yù)測。(4)對液壓支架結(jié)構(gòu)進行可靠性評估。從“宏觀”和“微觀”兩個層面描述復(fù)雜隨機載荷歷程及其概率特性。應(yīng)用損傷等效機理,將變幅循環(huán)載荷等效成具有當量應(yīng)力幅值的恒幅循環(huán)載荷。在此基礎(chǔ)上,基于全概率計算原理和統(tǒng)計平均算法建立液壓支架零部件(多部位損傷結(jié)構(gòu),相當于一個串聯(lián)系統(tǒng))的疲勞可靠性模型,該模型能客觀、真實地反映各損傷部位之間的失效相關(guān)性。
[Abstract]:Welded structures are widely used in mechanical engineering, vehicle ships, marine engineering, petrochemical and other fields. Some of the important structural parts bear complex random loads in their work, and fatigue failure is one of the main failure forms. It is of great engineering application value to study the probability attribute of structural fatigue life by using probability statistical theory and method to predict the fatigue life and reliability of structure more objectively and truly. In this paper, based on the fatigue probability life prediction of welded structures, the main research contents are as follows: (1) the fatigue life test and stress analysis of high-speed railway car body welded structures under laboratory conditions are carried out. According to the structural characteristics of the car body, two groups (two kinds of each group) fatigue life test and comparison samples were designed. For each group of tests, the fatigue test data of two different forms of specimens under different loading modes were obtained by using relatively simple axial tensile loading specimens, more complex bending loading specimens and corresponding fatigue test methods. At the same time, the static model of the structural specimen corresponding to the two loading modes is established by using the finite element method, and the stress of each dangerous point is calculated. By comparing the test life data, fracture position and stress distribution of the two kinds of structural specimens, the feasibility of using simple tensile fatigue test instead of complex bending fatigue test is discussed. In addition, the influence of average stress and its correction are analyzed. (2) different methods and effects of fatigue test data extraction are compared. Based on the test data, the life data which ignore the truncated data are statistically analyzed by using the probability statistical analysis method, and the distribution types and P-S-N curves of the life data are fitted. The maximum likelihood method and K 鈮，

本文編號：2496373