高强化柴油机铝合金活塞承载特性研究

许春光; 王国莹; 梁惠杰; 文洋; 李鹏; 赵志强; 张炜; 胡锦川

车用发动机 ›› 2020, Vol. 0 ›› Issue (2) : 35-41.

栏目

高强化柴油机铝合金活塞承载特性研究

许春光¹，王国莹¹，梁惠杰²，文洋¹，李鹏¹，赵志强¹，张炜³，胡锦川³

作者信息 +

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

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

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文章历史 +

摘要

重点研究某高强化柴油机铝合金活塞在典型服役工况下温度和应力随时间和载荷的变化行为，明确热机械载荷作用下活塞的承载规律，为活塞寿命预测模型建立提供依据，同时为材料研制提供载荷约束。首先建立了活塞有限元分析模型，利用温度及应力测试数据对模型进行了标定，进而基于该模型计算了标定工况稳态条件下以及怠速工况与标定工况交替变化条件下活塞温度和应力的变化规律。仿真结果表明：在工作循环内，活塞顶面温度波动幅值在28 ℃以内，由此引起的热应力波动幅值达到35 MPa左右，因此在活塞疲劳寿命预测时工作周期内高频热负荷的影响不可忽略；燃烧室喉口在热载荷作用下呈现压应力，在机械载荷下呈现拉应力，热机耦合载荷会导致沿销孔方向出现拉应力，沿主副推力面方向呈现压应力；在怠速工况与标定工况交替变化条件下，活塞喉口载荷变化最明显，应力与温度的变化率相关，应力幅值较高,该区域易发生低周疲劳损伤。

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.