摘要
针对经验公式计算活塞顶面传热边界不准确和热应力计算中引入位移约束产生人为应力集中的问题,采用燃烧模拟和有限元方法构建非线性接触对,研究活塞瞬态应力。首先,燃烧模拟仿真得到活塞顶面传热边界条件,并实现向有限元模型的瞬态映射;然后,用非线性接触模拟热和力在构件间的传递,对比有、无进气冷却效应下的活塞瞬态温度场,结合测温试验进行温度场验证,对比有、无非线性接触的活塞热应力场;最后,结合机械负荷,进行在交变热-机械负荷作用下的活塞瞬态应力场分析。计算结果表明:采用燃烧模拟和有限元方法进行活塞瞬态温度场研究,能更准确地反映活塞顶面温度在时间上的波动和空间上的不均匀;非线性接触改善了施加位移约束产生的人为热应力集中问题,对比排气侧,活塞进气侧的热应力高出11.9%;热机耦合应力不是热应力和机械应力的简单叠加,且热、机械应力有一定程度的相互抵消。
Aiming at the inaccurate computation of the heat transfer boundary on piston top surface in empirical formulas and the stress concentration caused by displacement constraints in thermal stress calculation, the combustion simulation and finite element method were used and the nonlinear contact was constructed to study the piston’s transient stress. The top surface heat transfer boundary of the piston under intake cooling effect was obtained by the combustion simulation and mapped to the finite element model. The non-linear contact was used to simulate the heat and force transfer between the components, and the temperature fields of the piston were compared under or without intake air cooling effect and verified by temperature tests. The thermal stress fields of the piston with or without nonlinear contact were compared, and the transient stress field analysis was performed under alternating thermal-mechanical loads. The results show that using the combustion simulation and finite element method to study the piston’s temperature field can simulate the top surface temperature fluctuations with time and the unevenness in space more accurately. The introduction of nonlinear contact can improve the thermal stress concentration caused by displacement constraints. The thermal stress on the intake side of the piston is 11.9% higher than the exhaust side. The coupled stress of the piston is not a simple superposition of thermal stress and mechanical stress, and there is a counteraction between the thermal and mechanical stresses to a certain extent.
作者
张俊红
王静超
徐天舒
李伟东
林杰威
袁一
刘志远
HANG Junhong;WANG Jingchao;XU Tianshu;LI Wei dong;LIN Jiewei;YUAN Yi;LIU Zhiyuan(State Key Laboratory of Engine, Tianjin University, Tianjin 300354,China;Tianjin University Ren'ai College, Tianjin 301636,China)
出处
《西安交通大学学报》
EI
CAS
CSCD
北大核心
2019年第5期16-23,122,共9页
Journal of Xi'an Jiaotong University
基金
内燃机可靠性国家重点实验室开放课题(skler-201713)
关键词
活塞
进气冷却
热机耦合
温度场
应力场
piston
intake cooling
thermo-mechanical coupling
temperature field
stress field
