Reducing noise, vibration and harshness analysis and reporting time by 70 percent in electric vehicle transmissions

Overcoming increasingly complex NVH analysis

Stellantis, one of the world’s largest automotive manufacturers, includes many leading brands with a history stretching back well over a century. Comfort has always been a key area of focus; thus, the company has considerably invested in noise, vibration and harshness (NVH) analysis. This has become even more important as the company increases its production of electric vehicles (EVs).

“Without a traditional internal combustion engine that masks noise, any sound from the transmission is much more noticeable in the cabin,” explains Gianluca Villella, technical lead for driveline and transmission NVH at Stellantis. “This makes noise and vibration analysis much more important to achieve customer expectations.

Previously for internal combustion engine vehicle transmissions, we had six or seven gear orders to consider. Now, in a hybrid dual clutch transmission, for example, we have to analyze almost 100 orders when considering main order and its harmonics in drive and coast conditions. This is more time-consuming and greatly increases the potential for human error in each test.”

To meet this challenge, Stellantis adopted Simcenter™ Testlab™ Neo software, which is part of the Siemens Xcelerator business platform of software, hardware and services, to streamline testing and enhance overall NVH analysis.

Embracing change

Although Stellantis had successfully used Simcenter Testlab for a long time, transitioning to Simcenter Testlab Neo was not a straightforward decision. “Simcenter Testlab worked well for us, but modern challenges dictated the need for change,” says Villella. “If you want to improve your knowledge and competences, it is important to go outside of your comfort zone. For my team, but also for all kinds of engineering, adopting new technologies is necessary to stay competitive. Although people were comfortable using the existing system, I had to show them the benefits of Simcenter Testlab Neo and how it would help us in the future.”

Villella highlights three key targets for the new solution: to reduce the amount of time needed to analyze large amounts of data, to eliminate human error and to summarize the results in a one-page overview.

Improving data analysis

Test engineers at the proving ground perform one single long acquisition run, including various maneuvers and engaged gears, with Simcenter SCADAS™ hardware and Simcenter Testlab software, producing vibration, acoustic and controller area network (CAN) recordings.

Previously, this data was manually split into multiple runs, each corresponding to one gear and one maneuver. This process required defining the time data selection and time data processing settings. After processing, an engineer plots each order to graphically identify the target violation points and populate a summary table.

With Simcenter Testlab Neo, rather than manually splitting each run for every gear and maneuver, the interactive display allows engineers to create time segments that will be processed into separate runs. Thus, instead of having to repeat this for every gear they are analyzing, they only need to set it up once.

Engineers can use the raw data, together with the targets (imported directly from a spreadsheet), as inputs, with the capability of dealing with time and frequency inputs. The Simcenter Testlab Neo process designer then compares orders to targets and identifies and reports target violations. After finishing processing and starting the reporting process, there is no reliance on visual analysis by an engineer. Simcenter Testlab Neo performs this automatically, eliminating the potential for human error.

Simcenter Testlab Neo then plots these outputs against the appropriate target using the queries feature, which produces an automatic summary report for engineers to review.

Saving time and eliminating human error

Transitioning to Simcenter Testlab Neo required a significant investment of time in learning and configuring the new platform; however, the savings were far greater. After creating the first workflow, users simply need to modify the Simcenter Testlab Neo process variables to quickly use it repeatedly.

“The types of analyses and evaluation are more complex now, so the savings are exponential,” says Villella. “Thanks to Simcenter Testlab Neo, once the workflow is set up, we save at least one day for each test analysis. In case of additional assessments, we can reuse the same workflow, which results in exponential time savings.”

Villella says the advanced capabilities of Simcenter Testlab Neo are essential to NVH analysis in hybrid and electric vehicles.

“Before adopting Simcenter Testlab Neo, we needed to manually process data for each test, and the resulting reports would consist of as much as 120 pages,” says Villella. “This was a time-consuming and error-prone process, which was stressful for the NVH engineer.”

Villella also emphasizes the importance of automating data collection. “Vehicles must be driven following a precise guideline; however, the test maneuvers can be completed incorrectly, making it challenging for the analysis team to discern what happened and creates more work to manually match data with the driving function. Thankfully, Simcenter Testlab Neo automates this process, saving us more time.”

Overall, Villella estimates that switching to Simcenter Testlab Neo has reduced the time spent on data analysis by 70 percent. Automating this process also removes human error and allows engineers to focus their attention where it is most needed.

“Leveraging Simcenter Testlab Neo allows our engineers to focus their skills on robust development and solving problems, which is far more valuable to the business, rather than spending time on recurring data analysis and reporting,” says Villella.

Aiming for future automation

To further speed up analysis in the future, Stellantis could pair Simcenter Testlab Workflow Automation with its analysis process. Using Simcenter SCADAS RS hardware, acquisition units in the field can send their data back to a central server in real time, and then Simcenter Testlab Workflow Automation can run their defined NVH analysis process. This way, an engineer in the office can see the results from the test before the testing team leaves the field, delivering results faster. This eliminates the need to send the testing team out a second time since engineers can quickly request further tests while they are still on site.

Analyzing impulsive noise

Next, Villella intends to investigate the possibility of using Simcenter Testlab Neo to analyze impulsive phenomena within vehicles.

“Within the transmission, we have subsystems that engage and disengage part of the driveline to save power,” says Villella. “This could generate an impulsive noise that could be heard in the cabin. Currently this analysis is done manually as the noise is not consistent, but we would save a lot of time if we could automate it. So, we hope to work on this and identify the correct algorithm and key performance indicators to develop a similar automated process to the one we are already using for the gear mesh order analysis.”