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Noise, Vibration and Harshness- Buzz, Squeak and Rattle Testing at MGA Research Corporation

Thu, Aug 20, 2020

Over the last few years, buzz, squeak and rattle, or BSR, have been rated as one of the top quality issues for automotive companies. In addition to 3 Months of Initial Service (3MIS), long term durability of interior and exterior components is an important factor to consumers. Detection and correction of BSR issues before vehicle production can save billions of dollars in warranty costs for OEM companies and their suppliers. Every manufacturer has established their own set of requirements for a component to pass vibration induced noise or operation noise performance. MGA, with their decades of expertise in the automotive testing field, caters to these different test specifications to eventually achieve the objective of diagnosing unwanted sound inside a vehicle cockpit.

Since a majority of all BSRs occur due to road induced vibrations, it is important to simulate these real world road conditions, in a controlled environment. MGA has two electro-dynamic shaker systems that can simulate a road condition on a test bed Each shaker system is installed in a semi anechoic chamber that has sound absorption walls to prevent reverberation. The background noise in each of these quiet chambers is less than 28 dB (A), so quite that it can’t be heard by human ears when the shakers are running without load, facilitating the best possible conditions to listen to even the faintest of sounds from a component.

The MB Silver single axis shaker is a quiet shaker capable of handling up to 200 lbs. of payload and can operate in Z, X and Y axis individually. It can perform vibration as a random wave or as a sinusoidal sweep input. The advantage of such a system is that a component can be excited at a particular acceleration level in an axis, enabling the engineers to perform root cause analysis of noise issues, one axis at a time.

 

 

This setup is extensively used by major OEMs for squeak and rattles testing of interior and exterior components.

The MB Dynamics Pitch and Roll-Multi Axis Shaker is a combination of two quiet shakers operating simultaneously to produce pitch and roll motion as experienced in a vehicle on road. This is a custom setup MGA has assembled for major OEMs and have the capability to setup customized shakers in future for other OEMs.  Many companies have their own test tracks with different road conditions like Belgian blocks, cobblestones, ropes, and so on. Vibration profiles simulating these roads can be played out using this setup.

 

MGA has operated these systems for nearly a decade and works proactively with MB Dynamics and Vibration Research to keep these systems and corresponding operating software up to date.

In addition to providing world class noise evaluation facilities in the form of semi anechoic chambers and purpose built squeak and rattle shakers, our BSR lab offers a number of Data Acquisition Systems in the form of microphones and a sound camera to quantify and analyze sources of noise. We are equipped to use up to 12 microphones at a time, enabling a complete coverage of a

component under test. The sound recordings are processed to produce numerical values for different aspects of sound quality. This quantification helps engineers to gain further insights into sound produced by an in-vehicle component under vibration or operation. Proper analysis of the data can pinpoint sources of sound that a human ear may fail to identify, especially in cases with multiple sources of noise occurring simultaneously.

With the ever evolving technology, vehicle components get more complex with multiple interfaces and joints that often lead to noise emanation that is difficult to isolate. With more than one source of sound, background noise and multiple parts vibrating at the same time, it becomes extremely difficult at times to pinpoint the exact source of BSR and perform root cause on it. MGA offers a solution to this with a state of the art Sound Camera from SM Instruments that locates notorious areas of squeaks and rattles, by providing a sound pressure contour.

The camera works in unison with the microphone array to generate a live pressure contour which accurately captures the emitted noise. Multiple noise hot spots can be displayed at the same time based on the sound frequency bandwidth selected. Sounds emitted simultaneously or intermittently can be captured and seen live, all inside one window screen of the software. The equipment is best suited to capturing hard to locate sounds from seats, instrument panels, HVACs, heavy machinery and so on. It is extensively used by most OEMs for their tests at vehicle level or component level testing.

With MGA, you have a one-stop solution partner who assists you from the development phase to performance and durability in implementing product and process improvements to isolate and eliminate BSR.

 

For more information on vibration testing, please contact Jay Shah at 248-878-6894 or email at jay.shah@mgaresearch.com.