本文關(guān)鍵詞： 活塞桿 疲勞斷裂 失效分析 壽命估算　出處：《山東大學(xué)》2012年碩士論文　論文類型：學(xué)位論文

【摘要】：大型往復(fù)式壓縮機(jī)作為過程工業(yè)生產(chǎn)中不可缺少的關(guān)鍵設(shè)備,其運(yùn)行可靠性直接影響著過程工業(yè)生產(chǎn),而活塞桿的早期疲勞斷裂是活塞式壓縮機(jī)運(yùn)行事故的主要原因之一。如何通過對活塞桿疲勞斷裂主要原因的分析,提出活塞桿的疲勞壽命估算方法,是本文作者的主要研究目標(biāo)。 本課題以山東華魯恒升集團(tuán)有限公司、中化平原化工有限公司、陽煤集團(tuán)淄博齊魯?shù)谝换视邢薰尽嫉V集團(tuán)嶧山化工有限公司與山東大學(xué)所達(dá)成協(xié)議為依托,以華魯恒升提供的6M32型壓縮機(jī)斷裂的3根活塞桿為主要研究材料,進(jìn)行了活塞桿斷口宏觀觀測、微觀斷口掃描電鏡觀測、拉伸試驗(yàn)、沖擊試驗(yàn)、硬度測試、化學(xué)成分測試、斷裂位置尺寸測量、表面粗糙度測量等實(shí)驗(yàn)工作,分析了活塞桿疲勞斷裂失效的主要原因。根據(jù)壓縮機(jī)結(jié)構(gòu)及實(shí)際運(yùn)行參數(shù),進(jìn)行了活塞桿受力計(jì)算及斷裂部位應(yīng)力計(jì)算。考慮活塞桿工況、材質(zhì)等的影響,篩選了基于活塞桿無損或微損檢測的壽命預(yù)測模型,對其壽命進(jìn)行了估算,對比了各種方法的估算壽命與實(shí)際運(yùn)行壽命的差值。 分析發(fā)現(xiàn)活塞桿疲勞裂紋主要在第二相組織或夾雜物位置萌生,名義應(yīng)力法較適用于活塞桿疲勞壽命估算,載荷類型、平均應(yīng)力、材料性能、金相組織、材料內(nèi)部缺陷、缺口、尺寸效應(yīng)、熱處理及表面狀態(tài)等對活塞桿疲勞壽命均有較大影響,Miner線性疲勞損傷理論及修正的Miner法則適用于活塞桿疲勞壽命估算。 試驗(yàn)結(jié)果表明活塞桿疲勞斷裂失效的主要原因?yàn)椋翰牧系牧W(xué)性能低于標(biāo)準(zhǔn)規(guī)定值；活塞桿斷裂部位位于軸肩應(yīng)力集中處,應(yīng)力集中程度較大,降低了其疲勞壽命；在斷裂處的應(yīng)力集中與循環(huán)載荷的共同作用下材料發(fā)生疲勞損傷,逐漸產(chǎn)生疲勞裂紋導(dǎo)致疲勞破壞�；钊麠U表面硬度和表面粗糙度對其疲勞壽命均有影響,表面硬化一定程度上可提高疲勞壽命,而表面粗糙度越小,疲勞性能越好�；钊麠U常用材料42CrMo與38CrMoAl的抗拉強(qiáng)度與其布氏硬度的比值在3.4左右,工程中可根據(jù)表面硬度值估算活塞桿抗拉強(qiáng)度甚至其疲勞壽命。分析發(fā)現(xiàn)在不同的疲勞壽命估算方法中,控制疲勞壽命估算精度的主要因素是各方法對平均應(yīng)力Re、應(yīng)力幅ΔR/2、應(yīng)力集中系數(shù)Kt、尺寸系數(shù)ε及表面系數(shù)β等的處理方式。在所選壽命的估算模型估算所得的壽命與實(shí)際運(yùn)行壽命比較后得出,當(dāng)使用基于Basquin公式的疲勞強(qiáng)度指數(shù)修正方法,其中系數(shù)采用四點(diǎn)法確定時(shí),所估算結(jié)果與實(shí)際壽命最相近。
[Abstract]:As the indispensable key equipment in the process industry production, the operation reliability of the large reciprocating compressor directly affects the process industry production. The early fatigue fracture of piston rod is one of the main causes of the operation accident of piston compressor. By analyzing the main cause of fatigue fracture of piston rod, the method of estimating fatigue life of piston rod is put forward. It is the main research goal of the author. This subject is based on the agreement reached between Shandong Hualu Hengsheng Group Co., Ltd, Sinochem Plain Chemical Co., Ltd, Zibo Qilu first Fertilizer Co., Ltd., Yanzhou Mining Group Yishan Chemical Co., Ltd., and Shandong University. The fracture surface of piston rod was observed macroscopically, microscopic fracture electron microscope, tensile test, impact test, hardness test and chemical composition test were carried out with three piston rods of 6M32 compressor provided by Hua Luhengsheng as main research materials. The main causes of fatigue fracture failure of piston rod are analyzed in this paper. According to the structure of compressor and actual operation parameters, the main reasons of fatigue fracture failure of piston rod are analyzed. The stress calculation and fracture stress calculation of piston rod are carried out. Considering the influence of piston rod working condition and material, the life prediction model based on nondestructive or micro-loss detection of piston rod is selected, and its life is estimated. The difference between the estimated life of various methods and the actual operation life is compared. It is found that the fatigue crack of piston rod is mainly initiated in the second phase structure or inclusion position. The nominal stress method is more suitable for estimating the fatigue life of piston rod, load type, average stress, material properties, metallographic structure and internal defects of the material. The notch size effect heat treatment and surface state have great influence on the fatigue life of piston rod. The Miner linear fatigue damage theory and the modified Miner rule are suitable for estimating the fatigue life of piston rod. The test results show that the main causes of fatigue fracture failure of piston rod are: the mechanical properties of the material are lower than the standard value, the fracture position of piston rod is located at the stress concentration of the shaft shoulder, the stress concentration degree is large, and the fatigue life of the piston rod is reduced. Under the combined action of stress concentration at fracture and cyclic load, fatigue damage occurs and fatigue crack is gradually produced. The surface hardness and surface roughness of piston rod have influence on fatigue life. Surface hardening can improve fatigue life to some extent, but the smaller the surface roughness, the better the fatigue performance. The ratio of tensile strength to Brinell hardness of 42CrMo and 38CrMoAl is about 3.4. In engineering, the tensile strength and fatigue life of piston rod can be estimated according to the surface hardness. The main factors controlling the precision of fatigue life estimation are the treatment methods of average stress Ree, stress amplitude 螖 R / 2, stress concentration factor Kt, dimension coefficient 蔚 and surface coefficient 尾. The comparison between life and actual service life shows that, When the fatigue strength index correction method based on Basquin formula is used, and the coefficient is determined by the four-point method, the estimated results are most close to the actual life.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：TH45

【引證文獻(xiàn)】

相關(guān)期刊論文 前1條

1 陳慧玲;黃林;;630T壓力機(jī)平衡缸活塞桿的改進(jìn)設(shè)計(jì)[J];科技創(chuàng)業(yè)家;2013年14期

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本文編號：1541718