Finite Element Analysis Of The Bionic Piston On The 465 Gasoline Engine

In Machinery parts all over the world, something like internal combustion engine cylinder and piston, crankshaft bearing and Casting top. The surfaces are in a state of relative motion and interaction. Therefore, friction and wear is inevitable, and wear will make the mechanical instrument efficiency lower, the working part changing and maintaining oftener, energy consuming higher. It is the main reason lead to the unworn of machine and loss of money. About eighty percent of parts were damaged by wear.Piston and cylinder wall is an important wear pairs. Their working life directly affects the working life and reliability of IC. It is very meaningful to improve the friction and wear between piston and cylinder wall in order to improve the IC's work- ing ability. In the fifteenth country science project—Applications of the Biomimetic non-smooth technology in engines, a new kind of biomimetic piston had been brought out. It is based on the principle of bionics and soil animals - earthworm surface features. According to principle of its movement in the hard soil with the humoral lubrication, we do modification on piston. This non-smooth structure on the piston skirt could accumulate lubrication when it is rich and give it out when lubrication is lack. So this structure can solve the problem fundamentally when there is a lack of lubrication in piston-cylinder system.In this paper, use the finite element software for mechanical stress calculation about the existing bionic piston. After analyzing the results, find out the effect of pore size and location on the overall stress distribution and deformation of the piston, and then sum up the law of it. Moreover, design optimization of the structure of the bionic piston based on the analytic results. The impact of non-smooth structure on the piston temperature distribution could be found in the results of calculation of the temperature field. Finally, do experiment to test the reliability of the new structure.3-D FEA of bionic piston at max. combustion pressure and max. lateral pressure makes the law of stress distribution. Summarized as follows:At the max. combustion press condition, stress concentration occur around the pores after loading. And the smaller the aperture, the more obvious the concentrated stress; With the aperture larger, the region around the hole has also been expanding in high stress, and the high stress zone formed. In the model which diameter greater than or equal to 4mm, those high stress zone will be the main crack regions. Bionic pistons pore size impact on the biggest overall stress. When the aperture smaller than or equal to 2mm, the biggest overall stress fall, and it isbigger than the original model while models'apertures greater than 3mm, furthermore, it is also increases with the aperture increases. With analyzing about the stress on the middle line of the skirt, it is found that in the vicinity of pores, the bigger aperture lead to higher stress. At the end of the bottom pore's location of the piston skirt, the smaller the aperture, the more obvious the stress concentrated.At the max. lateral press condition, As the skirt directly loaded, under the same conditions in the aperture, at this time ,stress concentration greater than at the maximum pressure condition; The greatest overall stress of the piston increase with the aperture decreased gradually. Under the max. lateral pressure, each model's largest deformation increases along with increases in aperture. But the deformation at the max. lateral pressure always less than it is at the max. combustion pressure working condition. Note for the piston skirt deformation, the gas pressure is a major contributing factor; Comparison and Analysis of the stress distribution on the skirt middle line shows that the biggest stress on the location near the piston head is basically the same, and the greatest stress is reduced with increasing of aperture around the pore which close to the bottom of the piston skirt.In two different conditions, the law of maximum stress curve on the middle line of the skirt is basically the same. Specifically, there are three characteristics:①The value of original model greater than the models with pores. This is due to stress concentration.②With the increase in diameter, the biggest stress on the skirt midline decreases. This is due to stress concentration increases with the diameter weakened.③In the max. lateral pressure condition, the biggest stress on the midline of the piston skirt is bigger than it is in the max. combustion working condition. The basic difference is about 10 MPa.In view of the above findings, aimed at reducing stress concentration to ensure the safety of the bionic pistons, optimizes non-smooth patterns and layout of the bionic piston further. There is a new bionic structure in this paper, which is drill pores in the minimum stress zone and notch at the hypo-low stress zone of the prototype. After calculation, it was proved that this structure can reduced stress concentration effectively, and keep every target the same with the prototype furthest.To analysis the temperature field of the piston is to array the commonly used formula for the boundary conditions and to per-calculate boundary conditions. Then give the boundary conditions of the three-dimensional steady-state temperature field calculation of the 465 gasoline engine piston based on analysis and statistical data through repeated calculation. To compute the prototype, 1mm and 2mm aperture respectively and to compare the results come out the conclusion: because of the increasing of the oil film and fluid of the lubricant, skirt temperature of the bionic piston is lower than the prototype. If oil film exit, the greater the aperture is the lower the skirt temperature is.