Loading Characteristics of Aluminum Alloy Piston for HighStrengthened Diesel Engine

XU Chunguang; WANG Guoying; LIANG Huijie; WEN Yang; LI Peng; ZHAO Zhiqiang; ZHANG Wei; HU Jinchuan

Vehicle Engine ›› 2020, Vol. 0 ›› Issue (2) : 35-41.

XU Chunguang¹,WANG Guoying¹,LIANG Huijie²,WEN Yang¹,LI Peng¹,ZHAO Zhiqiang¹,ZHANG Wei³,HU Jinchuan³

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Abstract

The variation of temperature and stress with the time and load for the aluminum alloy piston of highstrengthened diesel engine was mainly investigated under the typical running conditions. The loading law under thermal and mechanical loads was then determined, which provided the reference for building the life prediction model of piston and the load constraint for material development. The piston finite element analysis model was first built and calibrated according to the temperature and stress test data and was then used to predict the temperature and stress changing law under rated condition and alternating conditions between idle and rated condition. The results show that the amplitude of instantaneous temperature on the top of piston is less than 28 ℃ in a working cycle, the resulting thermal stress fluctuation is about 35 MPa, and so the influence of high frequency thermal load during the working cycle cannot be ignored as the piston fatigue life is predicted. The bowl rim of piston presents compressive stress under thermal load and tensile stress under mechanical load. The thermal and mechanical coupling load will produce tensile stress along the pin hole and compressive stress along the main and secondary thrust surface. The load variation of bowl rim is the most obvious under the alternating condition between idle and rated condition. The stress amplitude that is related to the thermal varying rate is large, so the low cycle fatigue damage occurs easily in this area.