【摘要】：連桿是汽車發(fā)動機中重要的傳動零部件之一,其質量對發(fā)動機的能量轉換及汽車的行駛安全性有重要影響。粉鍛連桿因其材料利用率高、機械力學性能好、鍛件精度高、生產工序少、生產成本低等特點,具有良好的發(fā)展前景。連桿在工作過程中受力復雜,需要具有足夠的強度與剛度。同時,連桿在周期性載荷的作用下,易產生疲勞失效,影響到發(fā)動機的正常工作。因此,需要開展粉鍛連桿的強度及疲勞分析研究,保證粉鍛連桿的使用可靠性。本文以某企業(yè)開發(fā)的粉鍛連桿為研究對象,建立了連桿在發(fā)動機典型工況下的有限元模型和疲勞壽命預測模型,分析了連桿在典型工況下的應力分布,研究了影響連桿的疲勞壽命的因素,采用疲勞分析軟件對連桿的疲勞壽命進行了預測,分析了連桿幾何不對稱因素對連桿強度及疲勞壽命的影響�；谟邢拊浖嗀BAQUS,建立了粉鍛連桿組件的靜態(tài)受力有限元分析模型,對連桿在三種典型工況下的受力情況進行了有限元分析,獲得了連桿的應力分布與變形。對比了兩種不同加載方式,即將載荷直接施加到活塞銷上和將載荷直接施加到襯套上,對連桿應力分布的影響。根據有限元靜態(tài)受力分析的結果,采用Fe-safe軟件對粉鍛連桿的疲勞壽命進行了分析和預測。對比了不同疲勞算法及平均應力修正方法對連桿疲勞壽命預測結果的影響,根據山東信義粉末冶金有限公司提供的粉鍛連桿的疲勞失效樣件的失效的形式、位置及最低疲勞壽命,確定了采用Stress-Based Brown-Miller算法和Morrow平均應力修正方法,來建立粉鍛連桿疲勞壽命分析預測模型。研究了連桿表面粗糙度和材料強度對連桿疲勞壽命及疲勞安全系數(shù)的影響。針對粉鍛連桿在實際鍛造過程中可能出現(xiàn)的幾何不對稱的情況,建立了連桿幾何不對稱的有限元分析模型和疲勞壽命預測模型,分析了三種不同幾何尺寸偏差對連桿的應力分布及變形量的影響,以及連桿幾何不對稱對連桿疲勞壽命及疲勞安全系數(shù)的影響。
[Abstract]:Connecting rod is one of the most important driving parts in automobile engine. Its quality has an important influence on the energy conversion of the engine and the driving safety of the automobile. Due to its high material utilization, good mechanical and mechanical properties, high precision of forging, less production process and low production cost, the powder forged connecting rod has a good prospect for development. The connecting rod needs to have enough strength and stiffness because of the complicated force in the working process. At the same time, under the action of periodic load, the connecting rod is prone to fatigue failure, which affects the normal work of the engine. Therefore, it is necessary to carry out the strength and fatigue analysis research of the powder forging connecting rod to ensure the reliability of the use of the powdered forging connecting rod. In this paper, the finite element model and fatigue life prediction model of the connecting rod under the typical working conditions of the engine are established, and the stress distribution of the connecting rod under the typical working condition is analyzed by taking the powder forging connecting rod developed by a certain enterprise as the research object. The factors that affect the fatigue life of the connecting rod are studied. The fatigue life of the connecting rod is predicted by using the fatigue analysis software. The influence of the geometrical asymmetry of the connecting rod on the strength and fatigue life of the connecting rod is analyzed. Based on the finite element software ABAQUS, the static force finite element analysis model of the powder forging connecting rod assembly is established. The stress distribution and deformation of the connecting rod are obtained through the finite element analysis of the stress condition of the connecting rod under three typical working conditions. The influence of two different loading modes on the stress distribution of the connecting rod is compared, that is, the load is directly applied to the piston pin and the load is directly applied to the bushing. According to the results of finite element static stress analysis, the fatigue life of powder forging connecting rod is analyzed and predicted by using Fe-safe software. The influence of different fatigue algorithm and average stress correction method on the fatigue life prediction of connecting rod is compared. According to the failure form of fatigue failure sample of powder forging connecting rod provided by Shandong Xinyi Powder Metallurgy Co., Ltd. The Stress-Based Brown-Miller algorithm and the Morrow mean stress correction method are used to establish the fatigue life analysis and prediction model of the powder forging connecting rod. The effects of surface roughness and material strength on fatigue life and fatigue safety factor of connecting rod were studied. The finite element analysis model and fatigue life prediction model of the connecting rod geometry asymmetry are established in view of the possible geometric asymmetry in the forging process of the powder forging rod. The effects of three different geometric size deviations on the stress distribution and deformation of the connecting rod and the influence of the geometrical asymmetry of the connecting rod on the fatigue life and the fatigue safety factor of the connecting rod are analyzed.
【學位授予單位】：山東大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：U464.133.2;TG316

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