UTAC CERAM is a private, independent group providing services in many areas of land transportation: regulation and approval, testing and technical expertise (environment, safety, durability and reliability), certification, public automotive events and driver safety training. UTAC CERAM also works in an official capacity with two French regulatory institutions that oversee standards for road-worthiness (Central Technical Organization) and standardization (Office for Automotive Standardization).
Scientists are confident that noise pollution can harm the health and behavior of all beings, so reducing the noise levels generated by cars, airplanes and machines is a requirement for supporting a sustainable future.
Governments worldwide, especially in Europe, are taking drastic measures to enforce more stringent vehicle pass-by noise (PBN) levels. In June 2016, Europe issued a plan for diminishing regular passenger car noise levels from the current level of 72 decibels (dB) to a maximum of 70 dB by 2020 and 68 dB by 2024. Achieving a 4-dB reduction will take an enormous effort, as vehicle manufacturers are already pushing engineering limits to remain below the current target.
Vehicle manufacturers and part suppliers will simply have to work hand-in-hand to deliver systems that meet individual and overall acoustic targets. Special attention will have to be given to the components generating the most noise: the powertrain, intake, exhaust and tires.
Every vehicle needs to be certified by the International Organization for Standardization (ISO) 362 standard, which has been revised in recent years. It now requires more extensive tests in order to even better represent the reality of urban traffic. Testing teams are already spending lots of effort on performing the regular homologation tests and have little to no time or resources to spare.
The reality is clear: Vehicles need to be designed to be able to pass the test the first time.
For decades, UTAC CERAM has helped vehicle manufacturers pass certification and homologation tests. UTAC CERAM is a private, independent group providing services in many areas of land transportation: regulation and approval, testing and technical expertise (environment, safety, durability and reliability), certification, public automotive events and driver safety training. UTAC CERAM also works in an official capacity with two French regulatory institutions that oversee standards for roadworthiness (Central Technical Organization) and standardization (Office for Automotive Standardization).
Over 400 employees work at two test centers in Linas-Montlhéry and Mortefontaine, France, as well as at customer sites in France and abroad. In addition, UTAC has subsidiaries in the United Kingdom, North America, Russia and China.
Vehicle pass-by noise homologation is one of many UTAC CERAM activities. Numerous vehicles are tested each year according to the ISO 362 standard on the exterior pass-by noise track at the Linas-Montlhéry site. Yet UTAC CERAM’s involvement in the automotive industry goes beyond simple homologation. The company offers solutions for automotive design and testing so manufacturers can be confident their vehicles will pass the ultimate homologation test.
For the purpose of mastered pass-by noise design, UTAC CERAM has invested in a state-of-art acoustic chamber. The large facility features fine-tuned sound insulation, a four-wheel drive roller bench and two rows of microphones combined with Siemens Digital Industries Software’s Simcenter Testlab™ software for analysis and Simcenter SCADAS™ hardware for acquisition. As such, it is designed to reproduce the conditions of exterior pass-by noise tests as accurately as possible.
The benefits of indoor pass-by noise testing are huge. Indoor pass-by noise testing lets teams perform accurate, perfectly reproducible tests in a controlled environment, independent of changing weather conditions. Since vehicle speed and gear shift are robotized, risk of human driver error is eliminated. However, tire noise is more difficult to accurately reproduce in a room, as it sounds different on a roller bench than it does on road surfaces. This is why Simcenter Testlab Pass-by Noise Testing software, part of the Simcenter™ portfolio from Siemens, features a tire noise model calculation that corrects tire noise data according to the ISO 362-3:2016 procedure.
Thanks to the repeatability of tests, results are more reliable. In the intermediate term, it is expected that indoor pass-by noise tests will be performed for vehicle homologation and will complement or replace exterior tests. Louis-Ferdinand Pardo, acoustic expert leader and department manager of electromagnetic compatibility (EMC) and noise, vibration and harshness (NVH) at UTAC CERAM, confirms this trend based on his experience as a member of the ISO committee defining the standard for pass-by noise level.
But the benefits of indoor testing go beyond eliminating the occurrence of chance, errors or incidents in a test. Testing in a controlled environment allows the user to implement advanced pass-by noise engineering techniques. The noise contributions of individual sound sources, such as powertrains, exhausts and intakes, can be evaluated and calculated to help set precise acoustic targets for the components.
Vehicle sound design is not about the reduction of noise levels alone. Today, an increasing number of hybrid and electrical vehicles are being used in urban areas. These vehicles drive fairly softly. The risk of accidents rises when no sound alerts pedestrians or cyclists of the presence, speed and direction of an approaching car. To preempt this risk, governments and institutions have been debating the necessity of equipping hybrid and electrical vehicle with noise-generating warning devices described as acoustic vehicle alerting systems (AVAS).
In 2016, the United Nations (UN) published a new regulation (UN 138) on minimal noise requirements that would enforce the fitting of such systems on new vehicles within a couple of years. In the same year, the United State National Highway Traffic Safety Administration (NHTSA) drafted a final rule establishing the federal motor vehicle safety standard (FMVSS 141) of minimum sound requirements for hybrid and electric vehicles.
Testing of AVAS-fitted cars will be best performed indoor as noise levels are by definition low and background noise should be excluded. Simcenter Testlab Interior Pass-by Noise Testing supports the definition of minimum noise levels by integrating the ISO 16254 standard (Acoustics – Measurement of sound emitted by road vehicles of category M and N at standstill and low speed operation – Engineering method) in its worksheets. With its state-of-the-art acoustic facility equipped with Simcenter testing solutions, UTAC CERAM is well positioned to support manufacturers of hybrid and electrical vehicles design sound for the alerting system.
To perform an indoor pass-by noise test, the vehicle is positioned and secured on the four rolls of the roller bench. The vehicle stands in the middle of the large chamber with two rows of about 20 microphones, each positioned on the sides of the chamber at an exact distance of 7.5 meters from the vehicle and a height of 1.2 meters. The microphones send their signals to the two Simcenter SCADAS hardware mobile data acquisition systems, part of the Simcenter portfolio, at each side of the room. Once the vehicle is positioned on the roller bench, the engineer starts the test. From that moment on, most of the procedure is automated. The engineer leaves the acoustic room for the control room, where he or she will be able to set up the parameters for the test and run it remotely. If necessary, the test can also be adjusted and started manually from a control box in the room.
At UTAC CERAM, the installation has been designed to ensure maximal testing productivity.
“We have selected the Simcenter testing solutions from Siemens for three main reasons,” says Pardo. “First, it offers excellent data quality and processing capabilities for indoor pass-by noise with algorithms that deliver accurate results, comparable to the ones obtained with actual exterior pass-by noise tests. Second, using Simcenter testing solutions ensures continuity and compatibility of tests performed indoor with tests executed outdoor with similar Simcenter systems. Third, we really appreciate the long-standing partnership with Siemens for acoustic engineering and testing.
“Siemens’ involvement in pass-by noise engineering is not limited to supplying measurement equipment; the company acts as a partner in research and development, providing solutions for acoustic source quantification and evolving towards early, predictive vehicle pass-by noise design. Siemens is also involved, as am I, in the definition of tomorrow’s ISO certification procedures, moving towards virtual homologation.”
New ISO certification procedures prescribe more exterior tests at run-up and constant speeds, and in various gear ratios. Those requirements can be reproduced in UTAC CERAM’s acoustic chamber, which allows the user to assess a design variant as well as prepare for vehicle homologation. Test procedures are preprogrammed in the chamber’s controller: the engineer only adjusts the parameters according to the requirements of the vehicle under scrutiny, opens the Simcenter Testlab worksheet and initiates the test. It then runs autonomously, with triggers starting and stopping measurements in Simcenter Testlab. Yoni Meyer, test engineer at UTAC CERAM, is an enthusiastic user of the software: “We benefit from almost all the implemented functionalities of Simcenter Testlab, and despite being advanced users, we still appreciate the easy-to-use worksheets and intuitive workflow approach.”
By using the postprocessing capabilities of Simcenter Testlab, further tasks, such as separation and quantification of noise sources, can be performed. The result is being able to clearly identify the noise contribution of individual components. This analysis will allow exact acoustic target setting on components, and means in the future the user will be able to accurately predict vehicle pass-by noise level based on component noise contribution.
Pardo concludes: “Working in partnership with Siemens, UTAC CERAM is looking to the future of automotive acoustic design, including virtual homologation, predictive pass-by noise design and sound optimization of AVAS-fitted vehicles.