Caba3D. An Insight into Rolling Bearing Dynamics

Transcription

1 Caba3D An Insight into Rolling Bearing Dynamics

2 The Schaeffler Calculation Chain The perfect tools for systems with rolling bearings Commercial solutions: Finite element method multi-body simulation, etc. Simpla System Bearinx Drive train Caba3D Bearing Telos Contact Level of system abstraction Thanks to its state-of-the-art simulation programs, Schaeffler offers the best possible support in the product development process 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. 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 relevant data regarding elasticity, contact rigidity, and environmental 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 software 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.

3 Caba3D An insight into rolling bearing dynamics 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-performance 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

4 Results W Caba3D The virtual bearing test stand 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 nevertheless 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 Double-row axial roller bearing, subjected to eccentric load: Hertzian contact pressure and roller speed are both displayed in color 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. Diagra Connecting rod bearings are subjected to constantly changing loads

5 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 simulation also provides us with information regarding the forces and torques that act on these elements. Furthermore, detailed information regarding contacts and behavior in the lubrication gap is also made available, including: Pressure distribution Lubricant film thickness Slippage modes and mixed friction conditions Contact power losses Damage parameters 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 bearing components together with the pressure and the slippage between the elements can be visualized, for example (see spherical roller bearing in the diagram below). izards Model ms Results The graphical user interface of Caba3D Spherical roller bearing displaying the distribution of contact pressure and slippage

6 Caba3D Caba3D a validated tool 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: Is the bearing subjected to sufficient load or do detrimental slippage modes occur? At which point of contact is the most power loss caused? Why is it here that the greatest power loss occurs? Is there a risk of wear under the assessed operating conditions? In addition, Caba3D is excellently suited to conducting investigations 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 components. 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. Slip in insufficiently loaded bearings Cylindrical roller bearing LSL at 15 % of at 15 % of recommended minimum radial load 100 % Slip of rollers [%] 75 % 50 % 25 % in unloaded zone measurement in unloaded zone Caba3D simulation in loaded zone measurement in loaded zone Caba3D simulation 0 % Inner ring speed [rpm]

7 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 particular, as it generates a large number of detailed results. Only by means of systematic validation can we ensure that the simulation 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 frictional 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.

8 Further information Commercial solutions: Finite element method multi-body simulation, etc. Simpla System Bearinx Drive train Caba3D Bearing Telos Contact Level of system abstraction Informative material on further stages of Schaeffler s calculation chain Simpla System Simulation with Rolling Bearing Expertise Bearinx High-Level Bearing Design MATNR / PCA / US-D / / Printed in Germany by mandelkow Schaeffler Technologies GmbH & Co. KG Industriestrasse Herzogenaurach Germany Phone info@schaeffler.com Internet 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.