Behind the scenes of Transfer path analysis

VIBES’ development of component-based TPA methodologies in order to win in highly innovative and competitive markets. Automotive OEMs and high-tech companies, such as BMW, Volvo and ASML, are continuously improving their R&D methods to increase product quality while reducing time and costs of both engineering and production processes. For Sound & Vibration engineering (‘NVH’ in automotive) a group of methods that has been significantly revamped over the past years is Transfer Path Analysis (TPA). With TPA, engineers evaluate the noise from various sources (e.g. road or engine noise), which propagates to the receiver (the driver or passengers) through various transfer paths.

With the variety of TPA methods growing over the past years, the need for a clear classification of methods and their pros and cons became inevitable. In 2015, VIBES’ own Dr. Maarten van der Seijs and Dr. Dennis de Klerk together with Prof. Dr. Daniel Rixen proposed a general framework to structure the different TPA methods in this paper. For the first time, similarities between well-known classical methods (such as mount-stiffness and matrix inversion) and the popular Operational TPA method have been made clear. More importantly, all recent approaches dealing with “Blocked Forces” were included and categorized into the component-based TPA family, in a way that helps the engineer choose the right approach, test bench design or source description for the case at hand.

At VIBES.technology these TPA methods are at the heart of our company. Over the past years we further developed the component-based TPA methodologies and we worked together with clients to tackle all types of sound & vibration issues based on measurements. Vibration assessments are done faster and at an earlier stage of the design process, while being more accurate at higher frequencies. Our tools (both the MATLAB toolbox and the DIRAC FRF measurement software) provide quality control and traceability for our clients while reducing both costs and risks. We believe that a modular way of working (“component-based”) with open data standards (such as the ASAM-ODS atfx format) allows engineers to work most efficiently on challenging topics.

Using component-based TPA, engineers obtain modular descriptions of individual components, with Blocked Forces being the independent quantities describing the active vibrations of the source.

• Using Frequency Based Substructuring, component descriptions are combined to predict the behavior of a full vehicle in a modular way. To further reduce costs engineers can even combine measured and simulated component models, for example using the Virtual Point method (which has the added benefit of giving insight in the model quality and reliability – topics we implemented in our DIRAC software).
• For active vibration sources, such as cooling fluid pumps in electric cars, the Blocked Force approach allows to predict sound levels in a car using a measurement of the compressor at a supplier. Two ISO standards are currently proposed for this topics, as Daniël van der Bosch discussed a few weeks ago on the SIA Automotive NVH Conference.

We proved the success of this innovative methodology with several major players in industry and are now leading experts in applying component-based TPA and Blocked Force technology. Right now, the industry is also picking up on these trends. For instance, in a recent white paper Siemens PLM Software also uses the VIBES framework and methods to shed light on their different TPA solutions. Through the usage of our techniques such as the Virtual Point Transformation, some of the drawbacks mentioned in the paper can already be overcome. With smart sensor data fusion (which is done real-time in DIRAC) typical drawbacks as directional errors in impact hammer testing or the application of forces at connection points are efficiently dealt with – with the added benefit that the engineer gets real-time insight in the measurement quality too.

We are excited to see that our enthusiasm for the continuous development and implementation of modern TPA methods is shared and appreciated across the industry. VIBES has built a professional team of dedicated experts and researchers, working together with leading partners in the industry to build the right tools and knowledge that help our clients win in competitive markets.

If you like to know more about the technology or are interested in a consulting project, you read more information on our website or send us an e-mail. Within VIBES we focus on new product development with a focus on software to perform high-quality FRF measurements, for example for usage in substructuring applications.

We are looking forward to helping you tackle your challenges.