KEY CONCEPTS
• A tool for simulating noise and vibration in bearings has been developed. 
• The goal is to improve the accuracy in the design, manufacture and installation of bearings. 
• The results have been validated by physical measurements.

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Meet the Presenter
This article is based on an Industry Insights presentation titled Simulation of Noise and Vibration of Systems with Real Rolling Bearings by STLE member Dr. Hannes Grillenberger on July 18, 2022. Industry Insights is a monthly virtual event series available for free to STLE members. These events provide a forum for members to collaborate with STLE industry peers and an expert on a specific topic who gives a brief presentation, then facilitates conversation by asking discussion questions and providing actionable takeaways. For more information, click here.

STLE member Dr. Hannes Grillenberger is a recognized expert on rolling bearing fundamentals, with a focus on rolling element bearing noise. He joined Schaeffler’s fundamentals department in 2012 after receiving his doctorate in physics at the University of Erlangen-Nuremberg, Germany. At Schaeffler, Grillenberger has worked on simulation methods for rolling element bearing friction, cage strength and noise. He holds several patents, has won conference awards, frequently publishes technical papers and presents at industry conferences. You can reach him at hannes.grillenberger@schaeffler.com.

Dr. Hannes Grillenberger

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Traditional tools that industries use to test bearing performance are focused on the system level and the bearings as a “boundary condition.” But for bearing performance, the internal geometry is crucial. Until recently, this internal geometry was only known by the manufacturers themselves through their own software or modules.

For optimum rolling bearing performance, it is advisable to consider the effects of the shaft and housing assembly in the bearing analysis. Given this, it just makes sense that the bearing should not be analyzed in isolation only, but mainly in terms of the entire operating system. 

The analysis of individual bearings as it interacts in the system is the goal of a simulation tool, Bearinx. This tool takes the following areas into account:
• Each raceway’s non-linear elastic behavior along with rib contacts in the bearing
• Elastic housing and shafts 
• Elastic or rigid tooth contact in gear stages along with distributed loads 
• Bearing seat expansion and more.

STLE member Dr. Hannes Grillenberger (key expert rolling bearing fundamentals) at Schaeffler Technologies had a major role in innovating this program and tool for simulating noise and vibration in bearings. The tool, which rates life calculations for the design and selection of bearings, is not currently commercially available.

“When this tool was created 25 years ago, there was no competitive tool like this on the market that was customized with internal knowledge on bearing design and calculation,” Grillenberger says. “It has since expanded to take system influences and interactions into account.”

The simulation tool models the noise signature emerging from bearings. Grillenberger created the noise components, ranging from normal noise due to small tolerances, to abnormal noise due to larger defects. It also pinpoints highly dynamic phenomena such as cage rattling and instability. There also is vibration interaction functionality within the system.

The components
The bearing simulation tool includes: 
• A quasi-static bearing analysis tool for drivetrains and gearboxes. It can model complete gearboxes and linear guidance systems and calculate relevant data on properties such as elasticity, contact rigidity and environmental influences. 
• A bearing dynamics tool. It analyzes the interior dynamics of a rolling bearing.
• A dynamic system simulations tool that combines capabilities of in-house and commercial programs such as Abaqus¹ to deliver a seamless simulation methodology. 
• A contact mechanics tool for testing lubrication conditions in each rolling contact to enable an analysis of the effects of surface coatings and damage. 

The simulation tool offers a variety of additional, relevant design criteria that go far beyond what is otherwise state of the art. Results have been validated through bench testing and field experience with simulation data supported by actual physical measurement stats. 

Capabilities
The simulation tool is typically used for the design of drivetrains with the focus on bearings—mainly for rating life and friction, but more and more with the focus on dynamics and noise. It calculates data for the following areas:

Gearbox
• Fuel consumption and torque from friction
• Power flow under all operational conditions
• Centrifugal pressure caused by planet gears
• Forces from gear mesh, chains and belts.

Shafts
• Section values along with bend lines
• Accounting for notches, the comparative stress curve
• Natural frequencies along with critical speeds
• Inertia forces (crankshafts and balancer shafts) that result.

Bearings
• The bearing’s precise internal load distribution 
• Any operating clearances
• Both loads and displacements
• The nominal and modified reference rating life 
• Safety—static and dynamic 
• Frictional power and torque 
• Cage stresses and loads.

Contacts
• Allowing for edge effects—non-Hertzian contact stress distribution
• The required hardness depth of the raceway.

“This simulation tool not only allows us to look at the individual bearing, but also to analyze entire applications,” Grillenberger adds. “Bearings and bearing systems can be automatically optimized to discrete design targets with the help of algorithms. This enables fast, automated selection of the ideal bearing solution for the specific application, as well as holistic system optimization.”

While the tool can simulate bearings of all sizes, noise simulation is focused on microlevel rather than macrolevel deviations—with different simulation system environments for different machines. It can be tailored to specific customer needs and integrated into customer simulation tool chains.

Future developments will be driven by sustainability and electrification. “These additional performance criteria need to be incorporated, including interactions with friction, noise (and dynamics),” Grillenberger concludes. “This will lead to expansion of the calculation portfolio and also additional interfaces and automation. For example, noise, electrical properties and temperature-related characteristics will be implemented. Then, in combination with automation and additional interfaces, a holistic and physically based optimization of the bearing can easily be done.”

The ultimate goal is to further create accuracy in the design, manufacture and installation of bearings. It also will help identify the best bearing and installation in each specific application.

Jeanna Van Rensselar heads her own communication/public relations firm, Smart PR Communications, in Naperville, Ill. You can reach her at jeanna@smartprcommunications.com.