Caba3DAn Insight into Rolling Bearing Dynamics

SimplaSystem

Level of system abstraction

Bearinx®Drive

train

Caba3DBearing

TelosContact

Commercial solutions: Finite element method

multi-body simulation, etc.

The perfect tools for systems with rolling bearings

Simpla – system simulation with rolling bearing expertise

Simpla, the Schaeffler simulation platform, is the top

level of the calculation chain. It provides support in the

creation, control, and analysis of mechanical system simulations

(e. g. wind turbines) in order to help understand and optimize

their dynamic behavior. The focus here is on the interactions

between our products and the customer’s design. Simpla uses

numerous interfaces to combine expertise from both internal

and external programs such as Bearinx®, Abaqus, Simpack, and

Samcef to create an efficient network of simulation methods.

Bearinx® – bearing design with an understanding of systems

Bearinx® allows complete gearboxes and linear guidance

systems to be modeled and calculated with all the rele-

vant data regarding elasticity, contact rigidity, and environmen-

tal influences. In addition to bearing parameters such as rating

life, safety factors, pressure curves, and friction values, the

results provided also include loads and the displacement of

other components. Data records and calculation models can

be exchanged with other programs via different interfaces.

Caba3D – a dynamic view inside the bearing

As part of the calculation chain, the Caba3D MBS soft-

ware allows a precise analysis of the dynamic processes

that take place inside a rolling bearing. This means that the

movement patterns of the bearing components, the forces acting

between them, and the frictional power that is generated

can be determined. These results allow statements to be

made regarding minimum load, the risk of smearing, cage

strength, etc.

Telos – where the focus is on contact

The basis of the calculation chain is contact simulation

using the Telos program. This program allows detailed

testing of the lubrication conditions in individual rolling contacts.

The effects of surface damage and coatings, for example, can

thus be analyzed.

Thanks to its state-of-the-art simulation programs, Schaeffler offers the best possible support in the product development pro-cess – from the dynamic simulation of an entire drive train through to the detailed simulation of contact conditions inside rolling bearings. The Schaeffler calculation chain includes CAE tools that are perfectly suited to the specific requirements of the design.

The Schaeffler Calculation Chain

An insight into rolling bearing dynamics

Caba3D

Caba3D is our view into the dynamic interior of

rolling bearings. This software makes it possible

for us to analyze and understand the internal

operation of bearings. This understanding forms

the basis for the development of reliable and energy-efficient

rolling bearings.

There is no static load in the bearing

Even when subjected to static external loads, the inside of the

rolling bearing has to withstand high dynamic loads, as the

point and the level of the internal forces change constantly as a

result of the moving rolling elements. When additional external

dynamic loads occur, such as vibrations, shocks, or speed ramps,

a quasi-static design (using our Bearinx® software for example)

is often no longer sufficient. In this case, the use of high-per-

formance dynamic simulation programs is necessary. In short,

a program such as Caba3D is required.

A program that grows with its tasks

Caba3D was specially developed to examine the dynamic

internal operation of bearings, while considering the complex

boundary conditions and deformations of the surrounding

structure that vary over time.

Presented for the first time in 1999, Schaeffler has continued

to develop this simulation program in close collaboration with

its users. This ensures that Caba3D always reflects the current

state of the art.

The name Caba3D stands for “Computer Aided Bearing Analyzer 3 Dimensional”

Software with rolling bearing expertise

Caba3D is a rolling bearing multi-body simulation program (MBS)

that allows us to carry out realistic dynamic simulations of all

rolling bearings. A distinctive feature of rolling bearings is that

the individual elements only engage as a result of frictional

connections and therefore the kinematics are not predetermined

as in the case of gear teeth, for example. In addition, most

bearings possess a cage for rolling element guidance, which is

not directly involved in the transmission of force but is never-

theless subjected to loads.

In order to correctly map these effects, Caba3D has, in contrast

to conventional MBS programs, a hydrodynamic friction and

contact model specially designed for rolling bearings, which is

based on Schaeffler’s technological expertise.

Using the virtual bearing test stand

Caba3D is our virtual bearing test stand, which allows us to

precisely and quickly assess targeted changes at the very

beginning of product development. This is an economical way

of ensuring that the best possible bearing is developed for

your application.

Double-row axial roller bearing, subjected to eccentric load: Hertzian contact pressure and roller speed are both displayed in color

The virtual bearing test stand

Caba3D

Results Wizards

Diagrams

Connecting rod bearings are subjected to constantly changing loads

and torques that act on these elements. Furthermore, detailed

information regarding contacts and behavior in the lubrication

gap is also made available, including:

• Pressuredistribution

• Lubricantfilmthickness

• Slippagemodesandmixedfrictionconditions

• Contactpowerlosses

• Damageparameters

User-friendly interface

There are two ways of building models in Caba3D. This can

either be done using a graphical user interface or by importing

from other programs such as Bearinx® or CAD tools. The

Caba3D user interface also offers a wide range of tools for

postprocessing and all results can be displayed as 2D or 3D

diagrams. For common analyses, wizards facilitate the creation

of the diagrams. In addition, the results can be animated in 3D

and saved as a video. By doing so, the movements of the bear-

ing components together with the pressure and the slippage

between the elements can be visualized, for example (see

spherical roller bearing in the diagram below).

During simulation, Caba3D takes all six spacial degrees of

freedom of each bearing component into consideration (rolling

elements, rings, and cage). Guiding functions are used to define

constraints, which can, for example, map the movement of a

planet gear bearing or connecting rod bearing. The forces and

torques that the bearing and its components are subjected to

can be specified as constant or changing over time.

Elastic or rigid system design

Caba3D allows us to simulate not only individual bearings, but

also systems with several bearings. This is required when a

bearing and its system interact dynamically, for example in

turbochargers.

Bearing elements and other bodies can be designed both rigidly

or elastically. For shafts and bearing cages in particular, it is often

important that their deformations are taken into consideration

to insure the correct system behavior. The contacts between

all the elements are always regarded as elastic in Caba3D.

Detailed results

In addition to the kinematics of all elements, a Caba3D simu-

lation also provides us with information regarding the forces

The graphical user interface of Caba3D

Results Wizards

Diagrams

Spherical roller bearing displaying the distribution of contact pressure and slippage

Model

Results

A variety of results: What is of interest to our customers?

Thanks to the broad range of results, we can answer many

questions with Caba3D, such as:

• Isthebearingsubjectedtosufficientloadordodetrimental

slippage modes occur?

• Atwhichpointofcontactisthemostpowerlosscaused?

• Whyisitherethatthegreatestpowerlossoccurs?

• Isthereariskofwearundertheassessedoperatingconditions?

In addition, Caba3D is excellently suited to conducting investi-

gations on the noise and vibration behavior of rolling bearings.

We also use the results of Caba3D as input variables for FEM

calculations in order to assess the strength of bearing compo-

nents. Furthermore, there is also an interface to our contact

simulation program Telos. By using this program, for example,

the influence of coatings on contact conditions can be analyzed.

Caba3D – a validated tool

Caba3D

48080 960

100 %

75 %

50 %

25 %

0 %

Inner ring speed [rpm]

Slip

of r

olle

rs [%

]

in unloaded zone – measurement

in unloaded zone – Caba3D simulation

in loaded zone – measurement

in loaded zone – Caba3D simulation

Slip in insufficiently loaded bearingsCylindricalrollerbearingLSL192332at15%ofat15%ofrecommendedminimumradialload

Achieving the highest level of customer acceptance through

validation

The validation of calculation programs is a fundamental task

that is of equal importance to software developers, users, and

end customers alike. This applies to a tool like Caba3D in par-

ticular, as it generates a large number of detailed results. Only

by means of systematic validation can we ensure that the sim-

ulation results and the products developed on this basis fulfill

our customers’ high requirements.

For validation purposes, we have verified the results of Caba3D

not only in theory but also in practice. This process involved

drawing a comparison with other calculation programs such as

Bearinx®. In addition, we conducted an extensive series of

bearing tests and compared a number of values, including fric-

tional torque, kinematics, and cage loads.

Proven in practice every day

The diagram at the bottom left is an example of a comparison

between Caba3D and a measurement on a test stand. It shows

the slippage of the rolling elements in a bearing where the

load is too low (the radial load amounts to only 15 % of the

recommended minimum load). The simulation results correspond

very well with the measurements.

As Caba3D is used on a daily basis as a design tool for our

rolling bearings, it is also subject to constant comparison with

real applications.

The bottom line is that with Caba3D we have an excellently

validated calculation tool for analyzing and designing rolling

bearings for your applications.

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Schaeffler Technologies GmbH & Co. KG

Industriestrasse 1 – 3 91074 Herzogenaurach Germany

Phone +49 9132 82-3396

E-mail info@schaeffler.com

Internet www.schaeffler.com

Informative material on further stages of Schaeffler’s calculation chain

Simpla – System Simulation with Rolling Bearing Expertise

www.schaeffler.com/Publication_Simpla

Bearinx® – High-Level Bearing Design

www.schaeffler.com/publication_bearinx

SimplaSystem

Level of system abstraction

Bearinx®Drive

train

Caba3DBearing

TelosContact

Commercial solutions: Finite element method

multi-body simulation, etc.

Further information

Every care has been taken to ensure the

correctness of the information contained

in this publication but no liability can be

accepted for any errors or omissions.

We reserve the right to make technical

changes.

© Schaeffler Technologies GmbH & Co. KG

Issued: 2014, October

This publication or parts thereof may not

be reproduced without our permission.

www.schaeffler.com/calculation