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Transfer Path Analysis: Accurate Load Prediction beyond the Traditional Mount Stiffness and Matrix Inversion Methods
Technical Paper
2014-36-0799
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
The source-transfer-receiver model to approach automotive NVH problems has proven its worth over the last decades. The approach allows splitting up an NVH problem into a source, for example engine vibration or road induced wheel vibration, a transfer system, for example the car body or car suspension, and a receiver such as the driver ear or steering wheel feeling. The analysis of such a system is called Transfer Path Analysis (TPA).
Whereas the determination of the transfer system for a TPA analysis through frequency transfer functions or a set of modes is fairly straightforward, the source side can pose quite some difficulties. For the sake of this paper, the sources are defined as the forces acting on the body structure of a car through the engine (for an engine noise problem) or suspension mounts (for a road noise problem).
The traditional way to determine these forces is through the use of the so-called mount stiffness method for soft mounts and the matrix inversion method for stiff mounts. Both methods work well in most cases. Both do have their limitations though. The mount stiffness method requires the availability of the (frequency dependent) mount stiffness which is not always the case and the matrix inversion method depends highly on the condition number of the FRF matrix and requires extensive test efforts.
This paper will therefore review 2 additional TPA methods that add additional load identification methods to the portfolio: operational TPA (or OPAX) which besides being a fast method requiring less instrumentation, also alleviates the need for detailed mount data for soft mounts, and Strain-based TPA which allows the determination of closely coupled forces that would otherwise result in an ill-conditioned matrix inversion problem.
OPAX simplifies the measurement effort need for TPA analysis and identifies the mount stiffness's as part of the path identification process using a parametric model. It is shown in this paper that the method is fast and works well in identifying the dominant path contributions to a noise problem.
Strain-based TPA uses strain sensors, rather than acceleration data, as response locations for matrix inversion. The advantage being that, whereas accelerations capture global deformation patterns very well, the strain sensors will be much more sensitive to local effects.
A number of industrial scale applications will illustrate the methodologies and demonstrate the added value compared to classical TPA.
Authors
Citation
Dom, S., Geluk, T., Janssens, K., and Van der Auweraer, H., "Transfer Path Analysis: Accurate Load Prediction beyond the Traditional Mount Stiffness and Matrix Inversion Methods," SAE Technical Paper 2014-36-0799, 2014, https://doi.org/10.4271/2014-36-0799.Also In
References
- Verheij J., Multipath sound transfer from resiliently mounted shipboard machinery, PhD Dissertation, Technische Physische Dienst TNO-TH, Delft, 1986.
- Magrans F.X., Method of measuring transmission paths, J. Sound Vib., Vol 73, No. 3, pp. 321-330 (1981)
- De Vis D., Hendricx W., van der Linden P., Development and Integration of an Advanced Unified Approach to Structure Bome Noise Analysis, 2nd Int. Conference on Vehicle Comfort, ATA, 1992.
- Mason J., Fahy F. Determination of the contribution of various regions of vibrating body to the sound pressure at a receiver point”, Proc. of the Institute of Acoustics, Vol. 12, Part 1, 1990, p 409-476.
- van der Linden P., De Meester K., “Airborne source strength measurements on the basis of pressure indicator inversion applied to an engine valve cover”, 4th ICSV, St-Petersburg, 1996.
- Verheij J.. Experimental procedures for quantifying sound paths to the interior of road vehicles, Proc. 2nd Int. Conference on Vehicle Comfort, Bologna, Italy, Oct. 14-16, 1992, p. 483-491.
- Starkey J. and Merril G.. On the ill-conditioned nature of indirect force measurement techniques, Int. J. Analyt. Experim. Modal Anal., 4(3), 1989, p. 103-108.
- Freymann R. and Stryczek R.. Noise path analysis and optimization, Proc. Unikeller Conf. 95, Zurich, May 30-June 1, 1995.
- van der Linden P. and Floetke H.. Comparing inverse force identification and mount stiffness force identification methods for noise contribution analysis, Proc. ISMA, Sept. 2004, Leuven, Belgium.
- Mas P., Sas P. and Wyckaert K.. Indirect force identification based upon impedance matrix inversion: a study on statistical and deterministical accuracy, Proc. 19th ISMA Conf., Leuven, Belgium, Sept. 12-14, 1994.
- Lohrmann M., Operational Transfer Path Analysis: Comparison with conventional methods, ICSV Conf., Daejeon, Korea, July 2008.
- Ewins D. and Liu W., Transmissibility properties of MDOF systems, Proc. 16th IMAC Conf., Santa Barbara, CA, US, 1998, pp. 847-854.
- Riberio A.M.R., Silva J.M.M. and Maia N.M.M., On the generalization of the transmissibility concept, Mechanical Systems and Signal Processing, 2000, Vol. 14, No. 1, pp. 29-35
- Maia N.M.M., Silva J.M.M. and Ribeiro A.M.R., The transmissibility concept in multi-degree-of-freedom systems, Mechanical Systems & Signal Processing, Vol. 15, No. 1, Jan. 2001, pp. 129-137
- Gajdatsy P., Janssens K., Desmet W., Van der Auweraer H.. Application of the transmissibility concept in transfer path analysis. Mechanical Systems and Signal Processing, vol. 24, no. 7, pp. 1963-1976, Oct. 2010
- Janssens K., Gajdatsy P., Gielen L., Mas P., Britte L., Desmet W. and Van der Auweraer H., “OPAX: a new transfer path analysis method based on parametric load models”, Mechanical Systems and Signal Processing, vol.25, no 4, pp. 1321-1338, May 2011, doi:10.1016/j.ymssp.2010.10.014
- Janssens K. et al., A novel path contribution analysis method for test-based NVH troubleshooting, ISMA Conf., Leuven, Belgium, Sept. 2008.
- Van der Auweraer H., Mas P., Dom S., Vecchio A., Janssens K., Van de Ponseele P.. Transfer Path Analysis in the Critical Path of Vehicle Refinement: The Role of Fast, Hybrid and Operational Path Analysis. Proc. SAE Noise and Vibration Conf., May 14-17, 2007, paper no. 2007-01-2352
- K., Aarnoutse P., Britte L., Deblauwe F.. Full vehicle validation of OPAX in comparison to traditional TPA methods. ICEM, Porto, Portugal, July 2012
- Janssens K., Mas P., Gajdatsy P., Gielen L., Van der Auweraer H.. A novel TPA method for test-based NVH troubleshooting. Noise-Con 2008, Dearborn, MI, July 2008
- Sachse D., Geluk T., Van Wayenberge T.. Accuracy of inverse load identification techniques for transfer path analysis. 2nd International ATZ Conf., June 2013
- Geluk T., Van der Linden P., Vige D., Caudano M., Gottardi S., Ciraolo F., Mir H.. Noise Contribution Analysis at Suspension Interfaces Using Different Force Identification Techniques. SAE, May 2011