Research On Fretting Wear And Fatigue On Mating Face Between Piston Crown And Skirt In Heavy Duty Diesel Engine

Piston crown and skirt of combined piston are separated,they are connected by bolts.The obvious advantage is that different materials can be used according to the load characteristics of the various parts,so that the piston can be designed to have light weight and high strength.Combined pistons are often operated in harsh environments such as high temperature,high speed,high load and poor lubrication.They are subjected to periodic loads such as high temperature gas pressure and high speed reciprocating inertia force such that the contact surface of piston crown and skirt is prone to fretting damage.Fretting damage can make the connection between piston crown and skirt loose,fatigue life reduce,resulting in greater security risks and economic losses.In this paper,simulation of a combined piston with wear in the piston skirt during the test is carried out to analyze the fretting wear and fatigue life of the piston skirt.Firstly,the finite element analysis model of the piston is established,and the boundary condition of the model is set according to the actual operation of the piston.The model is verified by the strain value measured in the cold test and the temperature data measured during the operation are used to determine the model's heat transfer boundary conditions.At the same time,the calculation method of fretting wear and the critical plane method for fatigue life prediction are introduced.The calculation method of fretting wear and fretting fatigue life is verified by the experimental data in the literature.The simulation results are in good agreement with the experimental results.And then use Python language to write a script,by modifying the coordinates of the node in the calculation file and calling the ABAQUS solver to do simulation analysis,and study effects of different bolt preload on fretting wear and fatigue life on the contact surface of the piston skirt.The results show that appropriate reduction in the preload of the connecting bolts can increase the life of the piston.