Hyundai uses Simcenter tools and partners with Simcenter Engineering Services to eliminate high-frequency whine
The Hyundai Motor Group is a multinational firm headquartered in Seoul, South Korea. With about 250,000 employees worldwide, Hyundai Motor Group’s mobility brands include Hyundai, Kia and Genesis.
https://www.hyundaimotorgroup.com/
One advantage of the Simcenter tools is that you don’t need to be a simulation expert to use them.
Hyundai Motor Group (HMG) has established itself as a leader in the electric vehicle (EV) market with popular cars such as the Ioniq 5. But to maintain its position, the company must continually strive to improve performance with each new product it develops.
Engineers at HMG have been using simulation for many years as a key part of developing internal combustion engine (ICE) vehicles but using simulation to improve EV performance presents new challenges.
Noise, vibration, and harshness (NVH) is a key focus for improving performance as it makes a significant difference in the overall user experience. ICEs mask many vehicle sounds, but since electric powertrains are much quieter, even the softest noises can become noticeable and irritating. EVs also produce sounds at different frequencies that wouldn’t always be picked up by traditional simulation methods. Therefore, simulation techniques need to be adapted to accurately predict any noises so component and vehicle designs can be modified to eliminate them.
To meet this challenge, HMG turned to Siemens Digital Industries Software’s Simcenter Engineering and Consulting services (Siemens Engineering Services), Simcenter™ 3D software, Simcenter Testlab™ software and Simcenter Nastran. Simcenter is part of the Siemens Xcelerator business platform of software, hardware and services.
An FE model of a structurally trimmed body.
Ji Woo Yoo, senior research engineer in HMG’s driving comfort virtual development team, explains that a particular acoustic problem associated with electric vehicles is a whistling or whining high-frequency sound. Although it is much quieter than road noise, the lack of an ICE to mask it means that once it is picked up by a vehicle occupant it becomes impossible to ignore. For simulation to be effective in development, it needs to accurately predict this high-frequency noise.
“Simulation has been used in the past to predict high-frequency sounds such as wind noise,” says Ji Woo. “But predicting this new unique sound from the electric powertrain is a new challenge. The most complicated aspect is combining the electric powertrain model with the vehicle model to predict exactly the noise experienced inside the cabin. This requires extensive calculation, which would be extremely time-consuming or simply not possible at all using previous methods.”
However, by using Simcenter 3D and Simcenter Testlab, HMG engineers were able to obtain each response separately, saving valuable calculation time and computer resources.
An FE model of an acoustic cavity.
The complexity derives not only from the high frequency of the sound but also because it is structure-borne and airborne. Typically, noise prediction software specializes in one or the other, so one simulation method cannot predict both simultaneously.
To overcome this, HMG worked with Simcenter Engineering Services to develop a method that could efficiently calculate both noise sources. For the structure-borne sound, the teams worked together to model the trimmed body of the vehicle in Simcenter Nastran using the finite element method (FEM). This predicted noise up to 1.5 kilohertz (kHz).
Once the structure-borne noise was fully understood, the team could make design modifications to reduce its effect. This involved adjusting the stiffness of the mount between the electric powertrain and the vehicle, as well as modifying the characteristics of the floor panels.
Shown are the main contributing exterior pressure loading panels.
Simulating the airborne noise is more complicated. The finite element method was again used to predict the acoustic radiation from the electric powertrain and acoustic excitation of the exterior vehicle panels. To achieve an accurate prediction, it was important to also model sound packages attached to the vehicle exterior – hood insulator, wheel covers and under covers. However, the vehicle was too heavy to model this with FEM since it would take far too much computing power. Instead, HMG worked with experts from Simcenter Engineering Services to apply a statistical energy analysis model. This is a method designed for solving high-frequency sounds; in this instance, it predicted noise up to 8kHz.
The noise was divided into source, path and receiver to quantify the strength of each – a process known as target cascading. By simulating this in Simcenter 3D, the team was able to improve the sound from each source much more efficiently than with traditional testing processes.
Using encapsulation to attenuate the main contributing electric powertrain panel.
“The Simcenter Engineering Services team worked closely with us throughout,” says Ji Woo. “We explained what we needed to achieve, and they showed us how to get the most out of the Simcenter software. Without their expertise, I don’t think we could have gotten the results we did.”
He’s also keen to continue to improve the new simulation techniques to realize more benefits for HMG. “Streamlining the process even further would make us more efficient,” says Ji Woo. “One advantage of the Simcenter tools is that you don’t need to be a simulation expert to use them. So once we have our processes and data standardized on Simcenter, we can introduce them to more engineers, which will free up our simulation experts for new projects.”
The Simcenter Engineering Services team worked closely with us throughout. We explained what we needed to achieve, and they showed us how to get the most out of the Simcenter software.