| The piston makes an important role on engines to realize the function conversion,and can determine the performance of engines.The current new technology of engines pursue low emission and high power,and the piston can not avoid the thermal load of environment and the mechanical load of pressure,which poses challenges to the strength and heat resistance.Spraying coating on the top of base has become an effective solution to reduce the temperature and heat dissipation of the piston substrate.In this paper,starting from the cast aluminum alloy piston model,a simulation comparison and analysis of differen t base materials and models with thermal barrier coatings are carried out.Research on the optimization design of the existing thermal barrier coating model,and evaluate the optimization model of the thermal barrier coating,and finally provide a referenc e for the selection of the thermal barrier coating scheme.First,Based on the concept of functionally graded layer,combined with consideration of the thermal barrier coating design scheme and pore issues,the equivalent physical parameters of the piston and thermal barrier coating are obtained.Using the corresponding empirical formula,combined with the structural characteristics of the piston,the thermal boundary conditions and mechanical load conditions of the piston are obtained.Secondly,Thermal analysis of base body is cast aluminum alloy and titanium alloy.It is found that the top temperature of the titanium alloy model is increased by304 K,the top heat transfer is reduced by 47.1%,and the maximum thermal stress is increased by 36.75 MPa.The thermal analysis of the thermal barrier coating scheme found that the temperature of the piston matrix dropped by 50 K,the top heat transfer was reduced by 51.2%,and the maximum thermal stress of the matrix was reduced by31.60 MPa.The titanium alloy matrix solution reduces the heat dissipation of the piston,but it poses new challenges to the strength and heat resistance of materials such as exhaust ducts and cylinder liners;the thermal barrier coating solution has obvious heat insulation effects,and the stress conditions conform to the material properties,and the program is highly feasible.Finally,based on the existing thermal barrier coating model,the comparison and analysis of three schemes by changing the distribution index,the different breadth of the gradient,the different breadth of the thermal barrier coating.This can provide a reference for the best scheme of the thermal barrier coating.Through the simulation analysis and calculation of the distribution index of 0.2,0.4,0.6,0.8,1.0,and combining the test results,it is concluded that the distribution index is 0.4 for the best heat insulation effect and stress;study different thickness,and the second model has a good effect on slowing down the peeling of the coating;through the compar ison and analysis of the thickness of the three thermal barrier coatings of 1.5mm,2.0mm and2.5mm,as the coating thickness increases,the heat insulation capacity and stability are both improve.The optimized final plan is: with thickness of 2.0mm,the distribution index is set to 0.4,and the second plan.The new scheme compares and analyzes the original thermal barrier coating scheme.The heat dissipation at the top of the piston has decreased by 2.96%,and the tensile stress at the interface of the bonding layer has decreased from 37.88 Mpa to 31.90 Mpa,a decrease of 18.7%.Compared with the existing scheme,the optimized scheme has greatly improved the temperature field and stress field,which reduces the heat dissipation at the top of the piston and significantly improves the stability of the thermal barrier coating. |
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