Finite Element Analysis of Dynamically Loaded Journal Bearings: Influence of the Bolt Preload

An improved FEM model was developed to simulate the elastic behavior of a connecting rod bearing, accounting for the displacements caused by the tightening torque applied to the bolts that join the cap and the rod. These initial displacements are added to the pressure induced displacements, to enhance the solution of the elastohydrodynamic bearing lubrication problem. The big end bearing of a marine diesel engine was modeled and analyzed under combustion process loads and inertia loads using the Newton-Raphson method together with the Murty’s algorithm. Some important differences between these results and other results published for the same bearing without the bolt preload are identified and discussed.

Three-Dimensional EHD Behavior of the Engine Block/Crankshaft Assembly for a Four Cylinder Inline Automotive Engine

Detailed formulations are presented for an EHD model that studies all the engine main bearings, considering the bearings, housing and crankshaft elastic deformations in connection with the hydrodynamic pressure fields as well as the quasi-static loads balance for this complex kinematic system. The calculation process uses the finite element method and the Newton-Raphson method for the numerical analysis. The elastic crankshaft behavior is quantified by a standard stiffness matrix. With two structural analysis steps, a condensed housing stiffness matrix is obtained to reduce the computing time. The transient evolution of the cavitation area is evaluated with Murty’s algorithm. This model is utilized to study a four cylinder inline engine.

EHD Analysis, Including Structural Inertia Effects and a Mass-Conserving Cavitation Model

The dynamic behavior of two elastic connecting-rod bearings is studied. The Newton-Raphson method and 8-node isoparametric elements for the lubrication analysis are used. For the structural analysis, 3-D elasticity assumptions are made and 20 nodes isoparametric elements are used. Inertia forces due to the kinematics of the structure are incorporated with the effects of the hydrodynamic pressures in the elastic deformations of the bearing. Comparisons with Goenka‘s results are presented for the General Motors connecting-rod bearing. A mass-conserving model used in conjunction with Murty‘s algorithm is presented for the transient evolution of the cavitation area. This model is applied for the EHD study of a Renault connecting-rod bearing.

An Optimum Short Bearing Theory for the Elastohydrodynamic Solution of Journal Bearings

An approximate method for solving the elastohydrodynamic (EHD) lubrication problem has been developed. The method is based on two assumptions: the separation of variable for pressure and a parabolic pressure distribution in the axial direction. To solve the governing equations, the Newton-Raphson method, in conjunction with Murty’s algorithm, is used. The finite-element and the finite-difference methods are then used to obtain approximate solutions. The rod bearing of a typical connecting rod is analyzed by the new method. The results are compared to the full EHD solution and the rigid bearing solution. Significant reduction in computation time is realized when compared to the full EHD solution.

The Elastohydrodynamic Solution of Journal Bearings Under Dynamic Loading

The Newton-Raphson algorithm was used in conjunction with Murty’s algorithm and the finite-element method to analyze the elastohydrodynamic lubrication of a journal bearing under dynamic loading. Cavitation boundary conditions were used. A realistic compliance matrix and load schedule were used in the illustrative example. Solutions for the film pressure, the film thickness and its rate of change with time were obtained as functions of the crank angle.