中文摘要：

活塞不仅是内燃机的主要运动部件而且工作环境最为恶劣。该文通过对活塞形态的改进,来提高活塞减磨、降阻的效用,以延长活塞的疲劳寿命。首先针对内燃机实际工况确定机械和热边界条件,然后对活塞进行热-机耦合仿真分析,观察其应力、应变和变形情况。受到与内燃机活塞运动情况接近的土壤动物蚯蚓的减阻、耐磨体表结构的启发,根据受试活塞外形尺寸,将宏观形态的仿生条纹和通孔设计加工在活塞裙部表面,以达到减磨、散热、提高活塞疲劳寿命的目的。活塞热-机耦合分析结果表明其整体受力为不均匀分布,基于此该文改进研究了变尺寸排布的仿生条纹深度、宽度、列间距。采用三水平三因素正交表制定9种仿生活塞试验方案,采用部分正交多项式回归设计对仿生活塞热-机耦合分析和疲劳寿命预测结果进行对比并优化仿生结构。选取3个最优活塞和标准活塞进行台架试验。最终发现仿生活塞比标准活塞疲劳寿命平均提高了8.8%,磨损量平均减小了90%,顶部温度平均降低了5%。该研究为活塞形态优化改进和延长内燃机整机疲劳寿命提供了参考。

英文摘要：

Piston is the main moving part of internal combustion engine, and works in the worst environment. During the reciprocating motion in the air cylinder piston endures the mechanical loads from multiple directions and the thermal load with high periodical variation. There are also contact friction between piston and air cylinder, poor heat dissipation and high temperature corrosion. All of these can make piston fatigue failure easy. First, this article made the dynamics analysis based on actual working conditions of internal combustion engine, and put forward to using the third thermal boundary condition to compute the temperature of temperature zone. So the boundary conditions of coupled thermo-mechanical analysis were got. Then we could observe the stress, strain and deformation of piston from coupled thermo-mechanical analysis results. Second, most animals have evolved and formed non-smooth surface, which can reduce drag and resist wear. The soil animal earthworm is one of the perfect animals, which has non-smooth surface. It shuttles back and forth in the soil, which was just like piston doing reciprocating motion in air cylinder. We copied stripes and holes from earthworm and enlarged them. The enlarging scale was decided according to piston size. Then the stripes and holes on the piston skirt were processed. The bionic piston could resist attrition and heat dissipation, and increase fatigue life. The coupled thermo-mechanical analysis results of standard piston showed that the stress of perfective aspect of piston was non-uniform. The stress was concentrated on the piston top and the third ring groove, and the maximum deformation was at the bottom of piston skirt. So this design made depth, width and space of stripe variable size. For the stripe, the closer to the top of piston, the larger the depth, width and space between columns. There were 8 stripes on the skirt from top to bottom, and every adjacent 2 stripes had the same size （1 and 2, 3 and 4, 5 and 6, 7 and 8）. Third, the three-level and three-fact