Using advanced testing solutions to streamline e-bike drivetrain NVH analysis

Shaping the future of mobility

MAHLE has been developing components for the automotive industry since 1920 and recently branched out into other areas, including complete solutions for e-bikes. MAHLE SmartBike Systems works with some of the most renowned brands in the bike industry, specializing in systems that are integrated, light and deliver a look and feel as close as possible to traditional bikes.

MAHLE‘s decision to invest in the e-bike sector marks a significant strategic shift. This diversification is not only a response to market demands but also shows the company’s ability to stay ahead of emerging trends in mobility. With their lower carbon footprint, e-bikes are becoming a preferred choice for urban commuters and recreational cyclists.

Motor noise is one of the key factors in deciding which e-bike to purchase. Prospective customers expect premium brands to deliver all the advanced features of an e-bike with minimal sound generated by the drive system.

“Most customers aren’t looking for extremely powerful, bulky systems,” says Diego Rodriguez, head of marketing. “They want a bike that looks good and feels natural. So we focus on small integrated drivetrains and smart connectivity that enables them to easily adjust behavior and performance.” MAHLE’s focus on small integrated drivetrains provides a sleek appearance, an important aesthetic factor for many riders. Additionally, the smart connectivity features provide users with greater control over their riding experience, allowing them to fine-tune their bikes to meet their preferences and needs.

MAHLE uses Siemens Digital Industries Software’s Simcenter™ SCADAS™ XS hardware, a mobile handheld device that can be easily fitted to a bike for data capture, to conduct noise, vibration and harshness (NVH) testing of its e-bike drivetrains, and Simcenter Testlab™ Neo software for analyzing data. These Simcenter integrated solutions are part of the Siemens Xcelerator business platform of software, hardware and services.

Testing the NVH levels of an e-bike is not simple as the interaction of mechanical and structural components can produce a wide range of noise and vibration patterns.

MAHLE’s use of Siemens Xcelerator provides the company with innovative tools that allow them to pinpoint sources of noise and vibration. This level of precision enables MAHLE’s e-bike systems to meet the highest standards of quality and performance, offering a quieter, more comfortable riding experience.

Complete data capture

The moving parts of the drivetrain create noise but also generate vibrations that transfer to the housing and frame of the bike. This can radiate the noise further so there is potential for the rider to hear both drivetrain noise and airborne frame noise.

So to ensure the best possible user experience, all these noise transfer paths must be analyzed during testing to identify design changes required to minimize noise.

In addition to minimizing noise, MAHLE considers the impact of these vibrations on the overall durability and longevity of the e-bike. Prolonged exposure to certain frequencies can contribute to wear on key components, potentially reducing the bike’s lifespan. By analyzing the interactions between the drivetrain, housing and the frame, engineers can make design adjustments that improve acoustic performance and enhance the bike’s overall durability.

At the end of the development process, MAHLE’s drivetrains go through intensive testing to confirm the noise levels are at an acceptable level. Federico Lopez, a MAHLE NVH engineer, explains that he uses many of the Simcenter SCADAS XS features to capture the required data.

“We record time signals from all the sensors and have a vehicle bus add-in connecting to the CAN-bus so we can see other parameters of the drivetrain,” says Lopez. “We also use signature throughput processing for detailed analysis of the rotating components along with the binaural headset to evaluate the noise from the rider’s perspective.

“Simcenter SCADAS XS is easy to set up and the measurements are precise, which helps us to understand the loudness, articulation index and roughness to better describe the subjective feeling of the noise rather than simply measuring the decibels.

“Capturing all this data with the drive unit mounted on a bike just as it would be in normal use allows us to fine-tune the drive unit’s noise for tonality and sharpness and deliver a better product. “The fact we can set up everything and monitor it via a tablet is a big advantage when we’re in the field.”

Using Simcenter SCADAS XS and Simcenter Testlab allows MAHLE engineers to capture a complete picture of the drivetrain’s performance, making sure that no detail is overlooked during testing.

Full NVH analysis

Lopez uses Simcenter Testlab Neo along-side Simcenter SCADAS XS to set up and analyze each test. Lopez notes the run averaging functionality is useful for comparing measurements across test runs and he particularly appreciates the rich processing capabilities.

“I have different templates defined for different objectives in Simcenter Testlab Neo, making it quick to set up,” he says. “Combined with automated reporting, this saves us considerable time in the testing process. Characterizing a complete drivetrain now takes just one hour while with other tools it could take as much as five hours.” This represents a time savings of 80 percent.

He also points to the advanced audio replay option as a key feature in filtering orders and notching frequencies. “We use audio replay for airborne and structure-borne measurements,” he says. “This helps us understand how the drivetrain will sound if we enhance the contribution of specific orders or remove certain frequencies.”

Characterizing a complete drivetrain in just one hour represents a major improvement in the development timeline, allowing MAHLE to move more quickly from testing to production. Accelerating the testing process enables the company to bring its products to market faster while maintaining high standards of quality. As the demand for e-bikes continues to grow, this efficiency will be crucial in helping manufacturers stay competitive and continue to innovate in the evolving electric mobility market.

For end-of-line testing, MAHLE uses the Simcenter Anovis™ system to check drive units and define boundaries for a pass or no-pass result. “Simcenter Anovis allows us to specify the conditions for identifying NVH patterns,” says Lopez. “Whenever components are changed to reduce NVH, we update the pass boundaries in Simcenter Anovis to reflect this. It’s a great solution for identifying issues and discarding units that don’t meet our high standards.”

By integrating predictive analytics into the testing process, test engineers can identify potential NVH issues earlier in the design phase, allowing for more proactive design adjustments.

Lopez believes all these solutions are essential to MAHLE’s work. “The Simcenter tools give us a unique approach to NVH analysis,” he says. “It allows us to clearly understand where units have failed and where noise levels are acceptable.”

Close collaboration

MAHLE was already using Simcenter SCADAS in its automotive division, so it did not hesitate to employ it for e-bikes. “Simcenter SCADAS XS is an incredible handheld device that allows us to collect all the data we need,” says Manuel Pal, head of testing and validation. “The ability to easily combine it with Simcenter Testlab made it a simple decision to use it.”

Lopez says that close collaboration with Siemens has been important to his team’s success. “Our dedicated Siemens engineer gave us excellent training on Simcenter Testlab. He explained signature processing, how to define channels and signal processing, measure FRFs and perform postprocessing analysis. He was always there for us for additional support, to assist with setting up the proper licensing and show how data sharing between the different Simcenter solutions works.

“Similarly, when we started using Simcenter Anovis, we had excellent support from Siemens on ensuring its compatibility with Simcenter Testlab and helping us to get the most value from the product,”

The ongoing partnership between MAHLE and Siemens is a testament to the power of collaboration in driving innovation. By working together, they can push the boundaries of what is possible in e-bike technology. This collaboration also ensures that consumers receive the highest quality products available on the market.

Incorporating simulation

To speed up the development process, MAHLE aims to add Simcenter simulation solutions to its Simcenter testing solutions. “With simulation, we could check the gear meshing frequencies between teeth without having to manufacture the gear set,” says Lopez. “We could also create a virtual model of the housing to predict noise radiation before building prototypes. This would allow us to try many more design ideas much faster and cheaper, which will lead to even better products.” In this process of using more simulation tools, physical testing is a key enabler to make sure models are realistic and accurate.

Incorporating simulation into MAHLE’s development process would be a game changer for the company. The ability to predict performance outcomes without needing to physically build each iteration would significantly reduce development costs and timelines.

Lopez is also intrigued by the potential of using artificial intelligence (AI) to process data. “We collect large amounts of data during testing that we simply don’t have the time or resources to fully analyze,” he explains. “We hope to take advantage of the AI capabilities of Simcenter to automate some of the analysis of these huge datasets and give us new insights on how to improve future designs.”

MAHLE’s commitment to innovation and quality is reflected in its approach to e-bike development. By leveraging their collaboration with Siemens and advanced tools like Simcenter SCADAS XS, Simcenter Testlab Neo and Simcenter Anovis, MAHLE not only ensures that its products meet the highest standards for performance and comfort, but also continues to push the boundaries of what’s possible in electric mobility. With an eye toward future developments like simulation and AI-powered data analysis, they are well-positioned to lead the next wave of advancements in sustainable transportation, ensuring that the future of mobility remains both efficient and exciting.