某船用柴油机活塞件疲劳寿命预测及损伤演化分析

Fatigue Life Prediction and Damage Evolution Analysis of Marine Diesel Engine Pistons

针对船用柴油机活塞在实际运行工况下出现活塞烧顶、活塞顶开裂等问题,运用有限元软件FEMFAT中的BASIC模块对船用柴油机活塞进行热机耦合仿真,模拟周期性最高燃烧压力、惯性力、热应力耦合作用下的活塞受力情况。利用Miner准则对活塞进行疲劳寿命预测,采用Aeran理论对活塞机械负荷、热负荷及热机耦合3种边界条件进行损伤演化分析,建立了活塞在不同载荷条件下的加速寿命模型,确定了活塞循环次数与其损伤演化之间的关系。

In order to solve the problems such as piston crown burning and cracking in the actual operation of marine diesel engines,a finite element method was used to perform the thermomechanical coupling simulation analysis of the stress field and temperature field of a piston under the combined action of periodic burst pressure,inertial force and thermal stress.These analysis results were then inputted into a BASIC module of the fatigue analysis software(FEMAFT)to analyze the safety factor of each part of the piston for finding areas prone to fatigue failure,and the fatigue life of the piston was predicted according to the linear fatigue cumulative failure rate criterion(Miner).Then,the fatigue damage accumulation theory(Aeran)was used to analyze the fatigue failure process of the piston under thermomechanical coupling conditions.And from this,an accelerated fatigue model of the piston under different loads was established to determine the relationship between the number of piston operating cycles and the piston damage evolution.