活塞作为柴油机关键部件之一,通过台架试验评估其使用寿命成本昂贵,因此为分析某型号国产研制改进后的柴油机活塞在热-机负荷作用下的疲劳寿命,以该V型增压柴油机的活塞为研究对象,建立活塞连杆机构装配体有限元模型,计算了活塞在热载荷下的温度分布和热-机耦合作用下的应力分布.在此基础上,将实测的柴油机p-φ示功图进行ASCII转码后作为疲劳载荷,采用名义应力法计算出活塞在4种典型存活率要求下的疲劳寿命.计算结果表明,由于活塞头部工作环境恶劣、头部和裙部的接触面受螺栓预紧力挤压,使得活塞的短寿命区出现在燃烧室侧壁面与活塞裙顶部截面突变处;活塞裙部疲劳寿命满足厂商设计使用寿命45 000 h,活塞头部仅在特定存活率下满足设计使用寿命45 000 h.
Fatigue life analysis of combined piston by steady state finite element method
As one of the key components of a diesel engine,the piston's evaluation of its service life through bench test-ing is costly.Therefore,in order to analyze the fatigue life of a domestically developed and improved diesel engine piston under thermal and mechanical loads,a research was conducted on the piston of a V-type turbocharged diesel engine.A finite element model of the piston-connecting rod assembly was established,and the temperature distribution of the piston under thermal loads and the stress distribution under thermal-mechanical coupling were calculated.Based on this,the measured diesel engine p-φ indicator diagram was ASCII encoded and used as the fatigue load.The nominal stress method was em-ployed to calculate the fatigue life of the piston under four typical survival rate requirements.The results indicate that due to the harsh working environment at the top of the piston and the compression of the contact surface between the top and skirt by the bolt preload,the piston's short life zone appears at the juncture between the combustion chamber side wall and the top section of the piston skirt.The fatigue life of the piston skirt meets the manufacturer's design service life requirement of 45,000 hours,while the piston head only meets the design service life of 45,000 hours under specific survival rate conditions.
万方数据
维普
