Anybody can bolt an engine and sled together to build a snowmobile and then stuff in insulation so the vehicle squeaks by government noise regulations. At Arctic Cat, however, sound is not an attribute merely to be damped out by trial and error but rather tuned during design to contribute to the overall riding experience. The goal is an Arctic Cat specific sound when the engine is revved up - a sound that adds to the thrill of the ride - and a vehicle so quiet you can talk to fellow riders when the engine is idling.A major challenge is delivering the sound riders want to hear yet stay within strict noise regulations. Compounding the problem is that testing snowmobiles under real-life conditions is difficult because the process depends entirely on weather conditions. Arctic Cat is meeting these daunting challenges by investing in some of the most advanced NVH technology available and a state-of-the art testing facility that leads the industry. This allows them to proactively shape the sound they know riders want to hear.
The company designs, engineers, manufacturers and markets snowmobiles and All-Terrain Vehicles (ATVs) as well as related parts, garments and accessories. The Arctic Cat brand name has existed for more than 30 years and is among the most widely recognized and respected names in the snowmobile industry.
Sound as a key product attribute
Clearly, Arctic Cat knows what its customers want to hear and feel when they ride a snowmobile. “Sound quality is critical to our product,” says Arctic Cat CEO Chris Twomey. “It defines our brand value and together with performance and handling it is a distinguishing feature that sets us apart from the rest of the market. The sound of the vehicle is a big part of that overall experience and our goal is to give them the consistent sound they want. At Arctic Cat, sound is a critical product attribute.”
Tugging in the other direction of this drive for the right sound is a strict set of sound-level standards required by numerous governmental agencies. Complying with these regulations is a top priority in the snowmobile industry and a major issue as new models are being designed.
Prototype vehicles typically are run through pass-by tests with microphones set up at a particular location to capture the sound level as the snowmobile is driven by. This outdoor method of testing noise emissions is particularly challenging, since the window of opportunity for testing is limited to four months annually when snow is in the right condition. Tests are time-consuming, and readings can vary greatly, even with the same vehicle on the same day.
A world-class leader in NVH
To overcome these limitations, Arctic Cat has taken a bold step in a traditionally frugal and conservative industry – they are the first snowmobile manufacturer to build a state-of-the-art NVH facility with the technology and equipment not unlike those found in the automotive industry. The 3,500-square-foot facility has a chassis dynamometer from AVL Inc., a semi-anechoic sound chamber from Eckel Industries Inc., a modal bay to test vehicles for vibration, and a sound-quality room that provides conditions for simulating and evaluating vehicle noise.
The facility houses some of the most advanced testing software and systems available. At the heart of the setup is LMS Test.Lab for acoustic and vibration testing: a multichannel data-acquisition solution with integrated testing, analysis, and e-report generation tools. Arctic Cat also has the capability to predict sound emissions and vibrations from individual components and assemblies as well as full vehicles with LMS SYSNOISE, which is valuable in evaluating and optimizing design concepts early in vehicle development.
“The new NVH facility will allow us to perform year-round testing in a controlled environment where we can gather more accurate data,” says Bala Holalkere, NVH Engineering Design Manager. He explains that the process of shaping the sound of a snowmobile begins by comparing prototype test data with a target-sound signature. A frequency analysis allows the NVH engineers to see the influence to the overall sound of various subsystems including the intake, exhaust, engine, tracks, and chassis resonance. Using LMS SYSNOISE as a basis for predicting sound emissions, engineers try various what-if concepts in modifying components and configurations to muffle unwanted noises and attenuate the desired sounds.
The goal, says Holalkere, is an overall linearity in loudness, with amplitude increasing steadily as a function of engine speed. This feedback sound is pleasing for riders but is often difficult to achieve with snowmobiles, which often exhibit fluctuations in loudness at various speeds.
“To meet these challenges, we are using the most advanced NVH technology available,” explains Holalkere. In addition to the facility and NVH technology here, we have assembled a team of NVH experts from the automotive and other industries – top people in their field. This investment makes Arctic Cat the world-class leader in NVH for the snowmobile industry, and LMS technology is at the heart of our NVH work. It allows us to leverage the expertise of our superb NVH team in both testing and predicting NVH characteristics.”
1Working with sound and vibration
One of the NVH engineers brought on board is Mark Christensen, who explains, “The vehicle must have outstanding performance in terms of acceleration and hill-climbing capacity as well as nimble handling,” says Christensen. “And it must be lightweight. The challenge is to balance these attributes with the right overall sound and feel obtained from the combined noise and vibration of all the various parts, assemblies, and subsystems.
That means a considerable amount of testing is needed, on individual subsystems as well as complete vehicles - ours and competitors’.”
Christensen explains that LMS Test.Lab is particularly useful in efficiently running repeated tests. “Test setup and required signal processing tasks only need to be defined once, after which they are saved in a dedicated template. The whole procedure is done automatically, so we can run tests over and over again. Because the environment is controlled, the tests are highly repeatable and consistent.”
According to Christensen, this knowledge base of data obtained from NVH testing is extremely useful in giving designers recommendations on the configuration of exhaust systems or intake boxes, for example, to minimize unwanted resonances and noises. “Developing a snowmobile is a collaborative effort between design, NVH and manufacturing,” says Christensen. “The information we obtain from the LMS system allows us to know how to avoid problems at the outset and gives us the information we need to proceed in the right direction during development.”
Product development and business strategy
“The NVH group is involved in development as early as possible,” says Roger Skime, Vice-President of Snowmobile Engineering. “That way, we can take advantage of the real power of NVH technology in helping guide the design, not just troubleshoot problems right before product launch.”
Skime says that the NVH knowledge base of past vehicle and subsystem tests is highly useful in indicating to designers what to do – and what not to do – on new models. “LMS SYSNOISE is especially useful in predicting sound envelopes around new, never-built configurations,” says Skime. “This predictive capability enables our engineers to change the design up-front early in development to achieve the right sound, before any hardware is built. The predictive capability of LMS SYSNOISE is where the future lies in NVH, to utilize the technology as much as possible in the early conceptual stages of development when changes are most easily made to refine and optimize designs early on instead of making last-minute changes downstream.”
CEO Chris Twomey describes the significance of NVH at the company. “With the considerable investment we have made in people, processes, and technology, NVH is now an integral part of our product development process and a key component in our long-term business strategy,” he says. “We want to do more than just comply with industry noise standards. We want to give customers the thrilling ride they want – and naturally expect – from an Arctic Cat snowmobile.”
