23 May 2012

LMS Engineering Services Develops a Hydraulic Exciter to Break Down HVAC Noise on a Vehicle

Leuven, Belgium, 23 May 2012 – World leader in test and mechatronic system simulation, LMS International develops a hydraulic exciter to break down HVAC noise on a vehicle. The dedicated dynamic exciter enables engineers to measure fluid borne noise transfer paths that can be integrated in a Transfer-Path-Analysis model.

As powertrain noise is reduced by the implementation of advanced NVH refinement and downsizing, existing noise sources become perceptible to customers. Noise targets are to be set on auxiliary noise, like the HVAC system.

Determining the sound source strength of the HVAC system is one thing. Managing the total HVAC noise is something else. Noise needs to be decomposed into distinctive sub-sources and subsequently multiplied by its transfer function in order to estimate its contribution to the total noise. To generate a dynamic pressure inside the HVAC system, LMS engineers have developed a dedicated exciter for hydraulic-noise transfer function measurement.

As measurements have to be carried out in full vehicle condition, a balance needed to be found between packaging constraints and sufficient dynamic pressure generation. LMS engineers used a local pressure sensor as a reference for the transfer function measurement (FRF). This new method results in high quality data that perfectly suits the Transfer-Path-Analysis method, allowing engineers to quantify the individual source generators inside the HVAC system.

LMS Qsources – advanced excitation hardware

Benefitting from more than 30 years of experience in noise and vibration technology, LMS Engineering Services has developed innovative excitation hardware over the last two decades under the brand LMS Qsources.

Covering a wide range of advanced excitation hardware, LMS Qsources seamlessly matches hardware with LMS software. This unique combination highly exceeds current market standards with regard to productivity and data accuracy, and hence customer’s expectations.


LMS shakers introduce dynamic excitation. LMS shakers are highly efficient exciters for modal analysis and structural analysis. They benefit from their exceptionally small design without compromising on accuracy, functionality and reliability.

The portfolio ranges from miniature shakers; that are so compact that they can be mounted where conventional shakers have no access, over integral shakers; significantly improving the efficiency of testing by eliminating all of the support and alignment work associated with conventional shaker testing, to an inertia shaker, designed for the very low frequency range.

Volume sources

LMS volume sources are sophisticated acoustic excitation devices have been developed to acquire acoustic FRFs at low, mid and high frequencies without disturbing the acoustic sound field with its presence. The integrated volume acceleration sensors give a real-time feedback of the emitted source strength and can directly be used as a reference for FRF measurements without any post-processing.

LMS Qsources excitation hardware is used worldwide by OEM and suppliers, aeronautics, chemical industry and on large structures such as ships, windmills, etc. to improve the acoustic performance on complete system level.

You’ll find more information on the LMS Website on:

  • Noise optimization of HVAC systems
  • Transfer Path Analysis
  • Qsources portfolio
  • Or contact LMS Engineering Services at qsources@lmsintl.com

About LMS, A Siemens Business

LMS is a leading provider of test and mechatronic simulation software and engineering services in the automotive, aerospace and other advanced manufacturing industries. As a business segment within Siemens PLM Software, LMS provides a unique portfolio of products and services for manufacturing companies to manage the complexities of tomorrow’s product development by incorporating model-based mechatronic simulation and advanced testing in the product development process. LMS tunes into mission-critical engineering attributes, ranging from system dynamics, structural integrity and sound quality to durability, safety and power consumption. With multi-domain and mechatronic simulation solutions, LMS addresses the complex engineering challenges associated with intelligent system design and model-based systems engineering. Thanks to its technology and more than 1250 dedicated people, LMS has become the partner of choice of more than 5000 manufacturing companies worldwide. LMS operates in more than 30 key locations around the world.

About Siemens PLM Software

Siemens PLM Software, a business unit of the Siemens Industry Automation Division, is a leading global provider of product lifecycle management (PLM) software and services with seven million licensed seats and more than 71,000 customers worldwide. Headquartered in Plano, Texas, Siemens PLM Software works collaboratively with companies, delivering open solutions to help them make smarter decisions that result in better products. For more information on Siemens PLM Software products and services, visit www.siemens.com/plm.

Note: LMS Virtual.Lab, LMS Imagine.Lab and SAMCEF are registered trademarks of LMS International or any of its affiliates. Siemens and the Siemens logo are registered trademarks of Siemens AG. All other trademarks, registered trademarks or service marks belong to their respective holders.

This press release was published by LMS International prior to Siemens PLM Software acquiring the company on January 3, 2013.

Primární kontakt

Peter De Clerck
+32 16 384 200