毕业论文文翻译-稳态和瞬态工况下柴油机气缸盖应力分布的实际测量与理论预测.doc

本科毕业论文 外文文献及译文 文献、资料题目： Measurements and Predictions of Steady-State and Transient Stress Distributions in a Diesel Engine Cylinder Head 文献、资料发表日期： 院 （部）：机电工程学院 专 业： 班 级： 姓 名： 学 号： 指导教师： 完成日期： ： Measurements and Predictions of Steady-State and Transient Stress Distributions in a Diesel Engine Cylinder Head ABSTRACT A combined experimental and analytical approach was followed in this work to study stress distributions and causes of failure in diesel cylinder heads under steady-state and transient operation. Experimental studies were conducted first to measure temperatures, heat fluxes and stresses under a series of steady-state operating conditions. Furthermore, by placing high temperature strain gages within the thermal penetration depth of the cylinder head, the effect of thermal shock loading under rapid transients was studied. A comparison of our steady-state and transient measurements suggests that the steady-state temperature gradients and the level of temperatures are the primary causes of thermal fatigue in cast-iron cylinder heads. Subsequently, a finite element analysis was conducted to predict the detailed steady-state temperature and stress distributions within the cylinder head. A comparison of the predicted steady-state temperatures and stresses compared well with our measurements. Furthermore, the predicted location of the crack initiation point correlated well with experimental observations. This suggests that a validated steady-state FEM stress analysis can play a very effective role in the rapid prototyping of cast-iron cylinder heads. INTRODUCTION Heavy-duty diesel engine cylinder heads experience severe thermal and mechanical loading, under both steady-state and transient engine operation. Consequently, cylinder head design is very sophisticated as it needs to house complex cooling passages for ensuring compliance with thermal stresses