LMS Solutions Guide Optional Applications for Noise and Vibration Testing

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Jeremy Wade
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1 LMS Solutions Guide Optional Applications for Noise and Vibration Testing

Noise and Vibration Optional Applications Optional Applications for Noise and Vibration Testing Standard Measurement Procedures - Pass-by Noise Testing In order to conform to the stringent ISO 362

2 Noise and Vibration Optional Applications Optional Applications for Noise and Vibration Testing Standard Measurement Procedures - Pass-by Noise Testing In order to conform to the stringent ISO 362 standard for pass-by noise, but also to use such pass-by test to further understand and improve the pass-by noise of a vehicle, LMS offers solutions both for exterior as for interior pass-by noise testing. It offers both technician oriented as well as engineeringoriented acquisition and processing capabilities, together with an extensive data-management and reporting functionality. Standard Measurement Procedures - Reverberation Time and Transmission Loss measurement For the characterization of acoustic materials, ISO 543 and ISO 140 define reverberation time and transmission loss characteristics. The dedicated LMS Solution includes the automation of the measurement, calculation and reporting of reverberation time, absorption coefficient and damping loss coefficients of materials or of the transmission loss index. Noise Source Identification - Acoustic Holography (Stationary Transient Time) Acoustic Holography is a powerful noise source identification method. By measurements of sound fields in a reference plane, results can be propagated towards the source to identify and quantify noise sources. The LMS solution includes a dedicated acquisition package with automated robot control, and solutions for analysis of stationary data, engine run-up and short transient phenomena such as door slam or engine start. 2

Noise and Vibration Optional Applications Noise Source Identification - Acoustic Intensity Analysis An alternative widely spread and standardized technique for identification and quantification of

The LMS solution will helps users to perform ISO-9614 compliant measurements, and guides users through the complete process of measurement definition, calibration, measurement and post-processing

By measurements of sound fields in a reference plane, results can be propagated towards the source to identify and quantify noise sources.

Laser Scanning solutions provide an excellent alternative in these cases.

3 Noise and Vibration Optional Applications Noise Source Identification - Acoustic Intensity Analysis An alternative widely spread and standardized technique for identification and quantification of noise sources is Acoustic Intensity Analysis. The LMS solution will helps users to perform ISO-9614 compliant measurements, and guides users through the complete process of measurement definition, calibration, measurement and post-processing such as acoustic radiation mapping, sound power calculation and source ranking. Acoustic Holography is a powerful noise source identification method. By measurements of sound fields in a reference plane, results can be propagated towards the source to identify and quantify noise sources. Advanced Sensors - Laser Vibrometry Many structures might be difficult or even impossible to instrument with classical transducers. Laser Scanning solutions provide an excellent alternative in these cases. LMS offers direct access to data measured with the Polytec Scanning Vibrometer solution, allowing to perform further 2D or even 3D operational deflection shapes or modal analysis. Advanced Sensors - LMS Misha Miniature shakers Originally developed to be used on engines to investigate internal contributions and structure vibro-acoustic sensitivity, the LMS Misha miniature shakers, extremely compact and light-weight, are excellent for contribution and modal analysis on small component and equipment like ventilation, steering wheel, electro-motors, etc. The LMS solution for Acoustic Intensity Analysis will helps users to perform ISO-9614 compliant measurements. The LMS Misha miniature shakers, extremely compact and light-weight, are excellent for contribution and modal analysis on small component and equipment. 3

Noise and Vibration Optional Applications Advanced Acquisition - High Speed Throughput In specific circumstances, where time data needs to be recorded for a large amount of channels at high sample

Requirements such as measurements of 500 channels at 200 khz for 20 seconds or 128 channels at 25 khz for several hours will lead to different architectures, but always guaranteeing fast data access

Advanced Acquisition - Stepped Sine and Normal Mode Testing When testing large structures such as aircrafts or other large structures, special excitation techniques will help to better excite and

4 Noise and Vibration Optional Applications Advanced Acquisition - High Speed Throughput In specific circumstances, where time data needs to be recorded for a large amount of channels at high sample rates, LMS can deliver an optimized solution. Requirements such as measurements of 500 channels at 200 khz for 20 seconds or 128 channels at 25 khz for several hours will lead to different architectures, but always guaranteeing fast data access after the measurement and a wide variety of data-processing capabilities. Advanced Acquisition - Stepped Sine and Normal Mode Testing When testing large structures such as aircrafts or other large structures, special excitation techniques will help to better excite and identify the modes. LMS provides solutions for stepped sine testing, where the structure is excited throughout a predefined frequency range and for normal mode testing in which multi-exciter input forces are controlled to isolate each individual mode separately. Advanced Modeling - Vibro-acoustic characterization Especially for acoustic cavities such as cabins or passenger compartments, advanced acquisition and modeling, it is extremely useful to combine vibration and acoustic excitation and response measurements. LMS provides a range of acoustic point sources for accurate acoustic measurements, ranging from low-frequency sources (20 Hz) to medium or high-frequency (8 khz). These measurements can optimally be processed with vibro-acoustic modal analysis, which will give a good insight of both acoustic and vibration modes and their interaction. Advanced Modeling - Transfer Path Analysis Noise problems inside a car or vibration problems at a specific aircraft location can result from different sources and will travel over different paths, typically attachments points of an engine to the carrying structure. Analyzing, ranking, modifying and evaluating those transfer paths can be performed with the LMS solutions for Transfer Path Analysis. Analysis can be done in the frequency domain, but also in the time-domain, allowing a meaningful sound quality evaluation. The single reference TPA analysis can be used for single harmonic sources such as an engine, a compressor of a refrigerator or a power turbine in its bedplate. Multi-reference analysis can be used for road noise analysis or propeller aircraft noise. Advanced Modeling - Rigid Body Properties When modeling complex structures and subassemblies, or simulating the dynamics of mechanisms, the rigid body characteristics of a subassembly might be too complex or inaccurate to calculate. With a Rigid Body Properties Calculator, LMS offers the possibility to use well-known FRF measurement techniques to extract essential parameters such as center of gravity, moments and principal axes of inertia. High Speed Throughput records time data on a large amount of channels at high sample rates. Tranfer Path Analysis provides insights in the sources and transfer paths of noise and vibration problems. The Rigid Body Properties Calculator allows to extract essential parameters like center of gravity, moments and principal axes of inertia. 4

Advanced Modeling - Virtual Car Sound Listening to and evaluating the sound of a virtual car, while driving interactively or replaying fixed profiles is possible with the LMS real-time Virtual Car

Advanced NVH Diagnostics and Analysis - Time-Frequency Analysis For the analysis of signals with strongly time-variant characteristics such as speed, sonar chirp or engine ignition, LMS offers

Continuous wavelet transformation, Wigner-Ville transformation or short-time FFT will provide better insights in the physical phenomena at the origin of the signal.

5 Advanced Modeling - Virtual Car Sound Listening to and evaluating the sound of a virtual car, while driving interactively or replaying fixed profiles is possible with the LMS real-time Virtual Car Sound Synthesis tool. Better target sound design is possible by the study of the perceptual influence of individual groups of signal components (e.g. orders,...), source contributions (e.g. intake, exhaust, engine, ) and transfer paths, or even by the evaluation of the sound quality of structural design changes. Advanced NVH Diagnostics and Analysis - Time-Frequency Analysis For the analysis of signals with strongly time-variant characteristics such as speed, sonar chirp or engine ignition, LMS offers advanced tools for detailed time-frequency analysis. Continuous wavelet transformation, Wigner-Ville transformation or short-time FFT will provide better insights in the physical phenomena at the origin of the signal. Noise and Vibration Optional Applications Advanced NVH Diagnostics and Analysis - Mission Synthesis It is critical for suppliers and end-users that specific equipment is neither over- nor under-tested. The Mission Synthesis solution helps you to derive, from the ensemble of the vibration environment and the loads encountered by a product during its mission, the best single-axis vibration specification to which it should be tested. Recorder Interfacing Digital recorders are still widely used for a lot of field measurements. LMS provides interfaces to several digital recorders, which allows you to transfer the time data and use the power of the LMS processing solutions, be it for transient, stationary or signature analysis. Customization LMS Test.Lab applications can interact with other hardware and software for customization and automation through any development environment that supports MS-Windows Automation, such as Microsoft.net, MS-Visual C++, MS- Office, Matlab and others. From embedding proprietary analysis algorithms, over controlling measurement robots to remote monitoring of measurement processes, LMS Test.Lab provides both the hooks and the functional components to comply with your most challenging test requirements, if not covered by the standard LMS Test.Lab applications. Pass-by noise testing checks on comformity to the stringent ISO 362 standard and also uses these test to further understand and reduce the pass-by noise of the vehicle. 5

6 LMS All rights reserved. The materials presented here are summary in nature, subject to change, and intended for general information only. Additional details and technical specifications are available at LMS INTERNATIONAL, LMS Test.Lab, LMS Virtual.Lab, LMS Tec.Manager, LMS CADA-X, LMS DADS, LMS FALANCS, LMS PolyMAX, LMS TecWare, LMS TWR and LMS CDTire are registered trademarks of LMS INTERNATIONAL NV. All other trademarks acknowledged. Images courtesy of Audi, BMW, Bosch, DAF, DaimlerChrysler, David Noels, ESA ESTEC, Flanders DRIVE, FORD, Honda, Husqvarna, Jaguar, John Deere, Perkins, Saab, Sarna and TWR. LMS INTERNATIONAL Researchpark Z1, Interleuvenlaan 68 B-3001 Leuven, Belgium phone: fax: LMS FRANCE Paris Phone: info@lmsfrance.fr Lyon Phone: LMS DEUTSCHLAND Leonberg Phone: info@lms-gmbh.de LMS ITALIANA Novara Phone info@lms.it LMS UK Coventry Phone info@lms-uk.co.uk LMS N. AMERICA Detroit Phone: info@lmsna.com Los Angeles Phone: Washington D.C. / Baltimore Phone: LMS JAPAN Yokohama Phone: info@lms-ja.co.jp LMS KOREA Seoul Phone: sales@lmskorea.com LMS CHINA Beijing Phone: info@lmschina.com LMS INDIA Bangalore Phone: info.lmsindia@lms.be WORLDWIDE For the address of your local representative, please contact LMS International, Belgium. LMS TEST DIVISION Leuven (Belgium) Phone: info@lms.be Breda (The Netherlands) Phone: Göttingen (Germany) Phone LMS CAE DIVISION Leuven (Belgium) Phone: info@lms.be Kaiserslautern (Germany) Phone: Coralville, IA (United States) Phone: LMS ENGINEERING SERVICES DIVISION Leuven (Belgium) Phone: info@lms.be Kaiserslautern (Germany) Phone: Detroit, MI (United States) Phone:

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