热-机耦合条件下气缸盖强度及疲劳寿命分析

Analysis of thermal-mechanical coupling strength and fatigue life of cylinder head

针对气缸盖在工作中承受交变载荷,容易形成疲劳损坏的现象,介绍了一种快速有效的方法来计算气缸盖的疲劳寿命。首先利用Hypermesh软件建立了有限元模型,针对不同区域设置了不同的单元密度,并通过有关参数来控制网格的质量。然后利用Abaqus软件分别计算了气缸盖的温度场、稳态应力场和耦合应力场,在温度场的计算中,将燃烧室火力面划分为3个区域,提高了计算精度。在稳态应力场计算中,将热应力场近似为稳态场,在保证精度的同时,为后续的疲劳分析提高了效率。最后采用疲劳分析软件MSC-Fatigue计算并得到了气缸盖的疲劳寿命分布。研究结果表明:燃烧室火力面一侧容易发生疲劳损坏,应作为设计的重点考虑部位。

Aiming that the cylinder head is easy to form fatigue damage when under the alternating load, a rapid and effective method to calculate the fatigue life of the cylinder head was introduced. Firstly, the FEM-model of the cylinder head was built by using Hypennesh software with arranging different density of elements and the element quality was guaranteed with the mesh parameters. And the temperature field, the steady-state stress field and the coupling stress field of the cylinder head were calculated by using Abaqus software. In the calculation of the temperature field, the combustion chamber firepower surface was divided into three areas to improve the calculation accuracy. In the calculation of the steady-state stress, the accuracy and the efficiency of the subsequent fatigue analysis could be improved when the thermal stress field was regarded as steady-state field. Finally, the fatigue life of the cylinder head was calculated by the fatigue analysis software MSC-Fatigue. The results indicate that the fatigue damage is easily occurred on the side of the combustion chamber firepower surface, and this should make an especially consideration for design.