Simulate Bearings with Simpack

Journal Bearing

Journal Bearing is a Force Element used to model radial or axial journal bearings using a nonlinear stiffness and damping law. This Force Element can model any kind of radial or axial bearing where a force law acting on only two Markers would be unsatisfactory. Simpack Journal Bearing acts between several Markers on the shell and one center Marker on the shaft. A 3D effect can be achieved by adding several Force Elements in a row.

Elastohydrodynamic Bearing

This Force Element can simulate hydrodynamic bearings by solving the Reynolds equation accurately and efficiently. The element includes rigid body hydrodynamics (HD), one-sided elastohydrodynamics (EHF) and double-sided elastohydrodynamics (DEHD). It allows the consideration of global temperature effects (TEHD) in the bearing and the surrounding solids. Special design parameters allow for easy and user-friendly consideration of oil bores, grooves ... Any level of detail can be simulated. The element can also simulate piston ring dynamics.

BEARINX®

Simpack BEARINX Map for Rolling Bearings enables the use of the BEARINX® software from Schaeffler Technologies in Simpack. BEARINX® allows the calculation of accurate bearing forces and torques for many rolling bearings.
Non-linear stiffness, coupling effects and bearing clearance are described by a characteristic field in a BEARINX Map (.bxm) file, which Schaeffler Technologies has to provide.

Simpack Rolling Bearings

Obstacles in Rolling Bearing Design and Selection

Bearings are the most frequently used machine element in power transmission. A poorly designed rolling bearing can quickly lead to damage of the bearing itself and the drive train. In the worst case, a chain reaction induces the total loss of your complete system. Detailed basic research works (for example PALMGREN, LUNDBERG, GAERTNER, see [1], [3] and [4]), introduced standardized formulas. These formulas enable engineers to properly design and select bearings in terms of carrying capacity by means of the bearings load spectrum. To calculate a reliable lifetime expectancy, the load spectrum must be as realistic as possible. However, due to unknown operational loads and complex interactions between the bearing and the system, the required representational bearing loads are hard to estimate. In addition, the demand on decreasing acoustic emission and detailed transfer path analysis is growing, which raises questions regarding the detailed rolling bearing dynamics and its influence on the system dynamics. To cover all these highly involved design topics confronting engineers required powerful tools for the dynamic roller bearing and system analysis.

Simpack Rolling Bearing Elements

To address the mentioned obstacles in Rolling Bearing analysis, Simpack offers the Force Element “Rolling Bearing”. This Force Element efficiently simulates all common types of rolling bearings by resolving the rolling element contacts under consideration of the inner geometry. On one hand, this approach takes the detailed transmitting behavior of a bearing into account, because it considers the non-linear stiffness characteristics, clearance and cross-coupling. The approach also covers the excitations generated by the bearing (for example due to rolling elements passing through the loaded zone). The high efficiency of this Force Element and the consideration of the transmitting and excitation effects of a bearing enable the engineer to generate realistic load spectra, which take the interaction of the rolling bearing with the complete system into account. In terms of carrying capacity, lightweight construction, and acoustic emission, this element makes the design and selection of the best bearing solution easier.

Supported Bearing Types

Ball Bearings: deep groove, angular, thrust, four-point
Cylinder / Needle: radial, thrust
Tapered Roller Bearing
Barrel and Spherical Roller Bearings

Key Features of Rolling Bearing

Local contact evaluation considering inner geometry: Non-linear stiffness, cross-coupling, clearance
Complete customization possible (pitch diameter, number of rolling elements, rolling element diameter, groove radii, roller profile, taper angle, …)
Modeling per row concept: Design as many bearing rows as you want
User-defined friction: Load-dependent and load-independent friction portions, speed-dependent friction coefficient
Local contact damping
Minimize the risk of an overdamped rolling bearing setup
Flexible bearings, even for multi-row bearings
Real-time capability (Convince yourself, test the example models provided within the Simpack documentation)
The high performance of the force element enables holistic simulations

Analysis and Outputs of Rolling Bearing

Fast, robust and accurate simulation of roller bearings as a stand-alone model or as part of a complete system
Overall radial, axial and tilting loads
Radial and axial loads per rolling element
Deflection of the complete bearing and of single rollers
Contact pressure
Load distribution (for example to calculate the modified reference rating life according to ISO16281 [4])
Power loss and friction torque
General flexible body outputs provided by Simpack (see Flexible Body Simulation Modules)

Example for a stand-alone and holistic bearing simulation

Analyze load distribution with variant roller profiles:
References:
[1] Gaertner: Ueber die Lebensdauer von Kugellagern, Dinglers Polytechnisches Journal, 1918
[2] Palmgren, A.: Ball and roller bearing engineering. 2nd Edition. S.H. Burband & Co., Inc., Philadelphia, 1945.
[3] ISO 16281: Rolling bearings — Methods for calculating the modified reference rating life for universally loaded bearings. ISO 16281, Technical Specification. June 2018
[4] Schlecht, B.: Maschinenelemente 2: Getriebe, Verzahnungen, Lagerungen. München: Pearson Studium, 2010.