The Road Load Data Acquisition (RLDA) team at Tenneco’s Heinrich Gillet plant in Edenkoben, Germany, faces the daunting task of exhaust system durability testing on a daily basis.
This task is especially challenging because exhaust systems need to last more than 10 years while still meeting tighter and tighter emission regulations. And, obviously, most of them are exposed to extreme conditions. To meet these requirements, exhaust manufacturers perform a variety of durability tests, collecting measurements on both proving grounds and public roads according to potential usage cases. To do this, the Tenneco RLDA team instruments numerous measurement points on the exhaust system using a multitude of sensors to retrieve any combination of strain, displacement, acceleration, temperature, tacho, CAN, and GPS data.
Not only does each campaign last on average two weeks, there are more than 25 campaigns each year. With each campaign requiring larger and larger amounts of data in shorter and shorter timelines, extreme flexibility is required from the small four-person team that needs to deliver top productivity and perform even more measurements than ever. It is essential then for the team to select the most flexible and reliable data acquisition system for the job.
“By design, it had to be a compact, robust, easy-to-use data acquisition system. We have little space to accommodate systems in the vehicle, and we want to avoid complex cabling, too,” said Dr. Zhijun Wang, RLDA Group Leader at Tenneco.
Klaus Rieger, RLDA engineer, added, “After a thorough benchmark, we selected the LMS SCADAS Durability Recorder. "We particularly valued the compact size and the robustness of the system, the flexibility to connect a broad range of sensors, and the ease of use of the software for test preparation and validation.”
At the beginning of each durability test campaign, the team receives the prototype vehicle from the customer. Then, the prototype is instrumented inside the Tenneco facilities. A detailed and tricky part of the campaign, this process can last up to one week. Part of this process is mounting the LMS SCADAS Durability Recorder; however, since the connection points are located on the front of the equipment, hooking all sensors onto the hardware is not complex, with even very complicated setups taking less than a day.
In parallel, the team prepares the test itself. With the previous software, test setup took 4 h, but with the LMS Test.Xpress software solution it’s reduced to less than 45 min. Following that, there is typically an additional confirmation check on-site to validate that everything is working before driving the car to the proving ground.
On the proving ground is where data acquisition reliability is essential. An average campaign can take from one day up to a week. And in this period the two technicians testing the car need to retrieve all the essential data. From time to time there is no possibility for a second run if parts of the channels were not correctly measured or critical events were missed. At the end of the test, the instrumentation and the prototype are stripped off and the vehicle is shipped back to the manufacturer directly from the proving ground—in most cases for further scheduled tests.
With 144 channels split between two units, the Tenneco LMS SCADAS system uniquely combines strain-based, vibration, and displacement measurement capability in one single module: its VB8 is the most versatile solution for durability-type measurements campaigns.
“With one universal module, we are able to measure any type of data on any channel without extra cabling or adapters. Whether we need to acquire additional strain data here or get more information about vibration levels using accelerometers, it can all be done instantaneously. Switching cable between modules is not necessary anymore. This saves hours of valuable testing time and gives us the extra flexibility to help us meet the toughest deadlines,” Wang said.
And the system can retrieve information such as speed or rpm from the vehicle’s CAN bus. “We foresee numerous possible applications to compare acquired data with CAN data. For example, this helps us to understand at which speed the resonance appears,” added Rieger.
The GPS signal helps retrace information in case a marker is missing. It helps answer the question: Where did this specific event happen? Was there a curve or a slope? The GPS integration is extremely precise and reacts dynamically. “I am certain of my measurements since I know that the test run has been marked with GPS data,” Rieger said.
Since the unit is completely integrated, there is no risk of failure due to a disconnected adapter or loose cable. With master-slave connectivity, the systems connect directly via an optical cable. Another advantage is the immediate data synchronization, which eliminates possible errors associated with manual synching.
“We have only a very short time to measure our data. We need to validate the data on the spot. With real-time signal calibration and quality checks, like the one-button LMS SCADAS Smart Control, I can concentrate on the measurement and not bother about anything else,” Rieger said.
Joëlle Beuzit, Marketing Manager Test, LMS International, wrote this article for SAE Magazines.