Residual Fatigue Life Prediction Of Engine Connecting Rod Based On Initial Stress Condition

Remanufacturing is a generic term about a series of technical measures or engineering activities on resuming or transforming the recycle products, which is guided by the product life cycle theory, depending on advanced technology and industry, aiming to raise the recycle product performance under the criterion of high quality, high efficiency, energy saving, materials saving, and high environmental. Remanufacturing can save about50%cost, about60%energy, and about70%materials, thus creating huge economic and social benefits. China is a manufacturing country, and rich in various reclaiming products, while many reclaiming key components have great residual value. And remanufacturing in China is a new industry, a lot of work need to be done. So, developing remanufacturing is a new growth pole to achieve recycling economy. On the whole, the prospect is cheerful.Fatigue life prediction of the remanufacturing parts is the theoretical basis for remanufacturing, and need to be solved urgently. Because engine connecting rod suffer very high intercourse variable load, the residual fatigue life is an important indicator to determine whether the recovery connecting rod having manufacturing value. This paper does the research around the remanufacturing of the reclaiming connecting-rod in WD615diesel engine. The main research contents, the research methods and the conclusion are as follows:①Mechanical analysis of the engine connecting-rod. Research and obtain the connecting-rod’s mechanics dates in one working cycle with the aid of ADAMS simulation software. The mechanics dates will be the initial load when doing finite element analysis.②The residual fatigue life prediction. Do the thermal analysis and thermal-structural coupled analysis of the connecting rod with the aid of ANSYS finite element software. The analysis consider the general loading conditions, including the thermal load, the tensile and compressive load, the assembly load existing in the small end of connecting-rod. The analysis getes the connecting rod’s temperature distribution and the heat affected zone, the stress dates of connecting rod in four working conditions. The paper also calculate and obtain the fatigue strength safety factor and the residual life of the three location, which are the location between the connecting rod small end and shaft, the location of the shaft, the location between the connecting rod big end and shaft.③Surface residual stress distribution model of the reclaiming connecting-rod. Measure the residual stress on the forged surface of the connecting-rod using the STRESS-X3000residual stress analyzer, and obtain the surface residual stress distribution.④The effect analysis of surface residual stress to fatigue residual life. The paper amend the thermal-structural coupled finite element data according to the data of the measurement experiment, calculate and obtain the fatigue strength safety factor and the residual life of the three location the second time. The calculate result indicate that the connecting-rod is suitable to remanufacture. The research based on initial surface residual stress predicts that the initial surface residual stress can raise the fatigue strength safety factor and the residual life. It is determined that the connecting rod without initial crack could be remanufactured.It saves a lot of time and resources by using finite element simulation and traditional fatigue calculation method. The research provides theoretical basis for remanufacturing and high-quality working.This work is sponsored by the university-enterprise cooperation project, that’s the key technology to remanufacturing of the engine connecting rod, between Shandong University and Weichai (Weifang) remanufacturing Co., Ltd..