The 3D Finite Elements Coupled Analysis Of Thermal And Mechanical Load In The Diesel Engine Piston

As one of the core spare parts of internal-combustion engine, the working environment of piston is execrable. Its working condition influences working dependability, durability and the emission performance of the internal-combustion engine directly. In working condition, the piston stands not only periodic mechanical load, such as high combustion gas-pressure, inertia-pressure, side direction pressure and frictional force, but also hot load produced by high temperature combustion gas. piston breakage, such as flaw, piston-ring glued and scuffing of cylinder bore are brought by thermal load and mechanical load colligating. Therefore,theoretic researching and finite element analysis on the piston were significant and practical value.The main research work and conclusion were as follow:(1) In this paper, through temperature value of the piston surface key dot, relation of working temperature of the aluminum-silicon alloy piston variety with the rotational speed of diesel engine was analyzed.(2) Based on Pro/E and Ansys software, a model is established for the piston of improved ZH1105W diesel engine with quadrangle omega shaped combustion chamber. As to optimize gridding and shorten calculation time,division dispose of surface,smartsize partition and portion gridding optimization were carried through by ANSYS. The result indicated that the result of optimization with 220741 nodes accord with the result of free meshing with 662827 nodes.(3) Compared with the temperature value of key dot, a heat transfer boundary condition of the piston is found out. The piston temperature field was calculated. Based on this, thermal stress and thermal distortion of the piston were analyzed by indirect finite element analysis.(4) The contact model of the piston ,the piston pin, portion cylinder sleeve, connecting rod and portion crank was established. commutative effect of the piston pin and the piston,the piston pin and connecting rod ,connecting rod and crank were simulated. Mechanical stress and distortion were calculated.(5) Based on thermal load and Mechanical load, the piston coupling stress field and thermal stress, pin-seat gives first place to mechanical stress, and piston distortion gives first place to thermal distortion.(6) Finally, intensity analysis and the thermal fatigue were carried on. in this paper. The study indicated that integrated stress and distortion of the piston accord with the design demand, while the temperature of first ring is very high. Corresponding Improvement measure were put forward.Through the finite element analysis of the aluminum-silicon alloy ZH1105W piston, the results of the temperature field, stress field and distortion of the piton were obtained, which offered certain method and reference to development and improvement of the piston.