基于缸盖等效构件模型的热机疲劳寿命预测与优化设计方法

Thermo-mechanical Fatigue Life Prediction and Optimization Design Method Based on Equivalent Component Model of Cylinder Head

为了更加高效、简便地预测内燃机缸盖的疲劳寿命并开展改进设计,基于缸盖等效构件模型提出了热机疲劳寿命预测与优化设计方法。依据火力面几何特征实现了缸盖模拟构件的数值建模,进一步利用Sehitoglu理论探究了服役载荷对缸盖热机疲劳损伤的影响,研究结果表明工作转速对缸盖热机疲劳寿命的影响最大,三种损伤类型中机械损伤占主导地位。最后,基于模拟构件和响应面试验设计方法开展了缸盖构件的优化设计,经优化后鼻梁区处最大应力降低了7%,疲劳寿命达到了6.7×10^(4)次循环,改善了缸盖构件的疲劳损伤特性,为服役工况下缸盖热机疲劳寿命预测与结构优化提供了理论依据。

In order to predict the fatigue life of cylinder heads of internal combustion engines more efficiently and simply and further to develop the optimization design,a thermo-mechanical fatigue life prediction and optimization design method was proposed based on the equivalent component model of cylinder heads.Numerical modeling of simulated components was achieved successfully by geometric characteristics of flame deck.Then applying the Sehitoglu theory,the effects of service loads on the thermo-mechanical fatigue damage were investigated.The results indicate that working speed has the most significant effect on the thermo-mechanical fatigue life,and mechanical damage is much dominant among the three damage types.Finally,based on the simulated components and response surface test design method,the optimization design of cylinder head components was carried out.The results show that the maximum stress is decreased by 7%at the region of nose bridge,fatigue life reaches 6.7×10^(4) cycles,and the fatigue damage characteristics of cylinder heads are improved,which may provide a theoretical basis for the thermo-mechanical fatigue life prediction and structural optimization of cylinder heads under service conditions.