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The height of comfort
How Renault is using Simcenter Testlab VPA to reach new levels of NVH optimization
What are the most important factors you consider when choosing a new car? Everybody has different needs depending on their circumstances. If you have a young family, you’ll probably want lots of room, for instance. Others may want something with faster acceleration or a higher top speed, although it depends which country you live in as to whether or not you’d be able to make full use of that!
Whatever your preference, you probably want a car that feels comfortable to travel in, either as a passenger or driver. And as cars become more autonomous, comfort factors are becoming a priority for many buyers.
Renault has always focused on comfort alongside performance and reliability, but recognizing its growing importance, they’re utilizing the latest simulation technology to deliver the ultimate comfortable driving experience.
NVH optimization
The key to vehicle comfort is the optimization of noise, vibration, and harshness (NVH). In the past, combustion engines would mask many sounds, but with the quieter motors of electric vehicles this is no longer the case. To combat this, in the early 2000s Renault created the Virtual Synthesis in Acoustic (VISA) project to help different teams work closer together to optimize the NVH of their interacting components.
VISA allowed teams to assess NVH behavior throughout the development process and implement a modular, system-driven design methodology to bridge the gap between Renault and external suppliers.
But it was limited by the technology available at the time. For instance, there was no way of characterizing noise and vibration sources in an invariant way. It was also difficult to exchange data between testing and CAE, and there were no existing boundary conditions for the new complex hybrid-electric architecture.
Philippe Mordillat, NVH simulation expert at Renault explains that “in the end, 90 percent of the use cases we could analyze were linked to pure components weakly coupling; for instance, softly mounted and applications for low or mid-frequency booming noise. We wanted to extend the applicability of the methods to higher frequencies such as road noise and pass-by noise cases.”
Next generation collaboration
Renault’s desire to continually improve their development processes led to a strategic collaboration with Siemens Digital Industries Software. Since 2016, the two organizations have been working together to improve the existing VISA platform by taking advantage of the latest simulation technology.
The vision was a holistic, company-wide process to reliably assess NVH performance of an assembled vehicle virtually, without a physical prototype. It needed to be available to any stage of development and accessible to all engineers, not just simulation experts.
To meet these requirements, Simcenter Engineering and Consulting Services, and Simcenter Test and Engineering services, collaborated with Renault engineers to leverage the capabilities of Simcenter Testlab Virtual Prototype Assembly (VPA).
Together they deployed a component-based transfer path analysis (TPA) method that could identify invariant noise sources that were previously not distinguishable. Not only does this method pinpoint the component generating the noise, but it also highlights the way the component is connected and interacts with other subsystems.
The improved tool also allows Renault to exchange key data with suppliers without risking any breach of confidentiality – no detailed specifications or geometry are shared, only curves such as frequency response functions (FRFs) or loads. This enables both parties to better set common criteria and targets to work towards for each component.
Simulation for all
The new platform will initially be mainly used by Renault’s CAE department who have an important role in making it more widely available. They will build up a database of components that is stored in Simcenter Testlab and can be easily searched and re-used in each new development. As the database grows, more engineers across the company will be able to make use of the platform to create virtual assemblies using the pre-built components. As Mordillat says, “The reason for using Simcenter Testlab VPA is to have an easy and standardized process that users can follow in their everyday activity, no matter which engineering site or vehicle model they are working on.”
It hasn’t taken long to see a positive impact from the new development process. “Using Simcenter Testlab VPA expanded our applications for NVH prediction by a factor of five,” says Mordillat.
And it’s going to keep getting better.
The next step is to integrate the new process with Renault’s GREEN (Global and Rational Energy EfficieNcy) platform. This is another Siemens collaboration powered by Simcenter Amesim which improves the evaluation of hardware and software controls in hybrid-electric vehicles. CAE engineers will build models on the GREEN platform and then combine them in the Simcenter Testlab VPA with test-based components created by measurement specialists to build the virtual assemblies for NVH predictions.
The end result will be more accurate prediction of design modifications in the virtual environment, meaning less physical testing is required. The number of prototypes will be reduced and new vehicles with fully optimized NVH will be developed faster and cheaper.
As we progress towards fully autonomous vehicles, comfort will certainly be high on any car-buyer’s wishlist. And thanks to this innovative collaboration, Renault will be ideally positioned to deliver the most comfortable vehicles of the future.
