Finite Element Study on Piston Assembly Dynamics Emphasis with Lubrication

The paper presents the results of the finite element study conducted by developing a 3D model of piston assembly with its components. The complete 3D model of the crank, connecting rod, piston, wrist pin, piston rings are developed using UG-Nx-3 software and finite element models of all these components are generated using Hypermesh software to solve in L.S.DYNA solver. The piston assembly is simulated by providing proper boundary condition to impose the true working condition. The effect of hydrodynamic lubrication on the piston skirt is introduced by solving 1D Reynolds equation. The inter ring gas pressure is calculated by using appropriate models and applied on the piston rings. In this work piston assembly component motions are studied. The piston and ring motions in axial and lateral directions along with piston tilt are studied. The finite element study results are compared with results obtained from the earlier developed numerical model. The effect of considering piston skirt as rigid and elastic during the F.E. Analysis are discussed and concluded that, it is better to select the piston skirt as elastic during analysis considering lubrication effect. The approach used to obtain the piston secondary motion and to study their effects on lubrication seems to be easy, cost effective and less time consuming. The finite element procedure can serve as an effective tool in the analysis of piston assembly motion.