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This paper discusses an approach to identify critical car panels and to derive detailed experimental models for these critical panels. The research was conducted in the framework of the Brite/Euram project SALOME and the EUREKA project HOLOMODAL. The panel identification method is based on a numerical or experimental contribution analysis, assessing the partial noise contributions of individual panels to the interior noise. The second step in the approach consists of the derivation of detailed modal analysis models for the critical panels. A novel Electronic Speckle Pattern Interferometry (ESPI) system was developed, and integrated in a classical CAE system. The components of this system are briefly reviewed, and their application to several industrial cases is shown.

In order to optimise the vibro-acoustic behaviour of panel-like structures in a more systematic way, accurate structural models are needed. However, at the frequencies of relevance to the vibro-acoustic problem, the mode shapes are very complex, requiring a high spatial resolution in the measurement procedure. The large number of required transducers and their mass loading effects limit the applicability of accelerometer testing. In recent years, optical measuring methods have been proposed. Direct electronic (ESPI) imaging, using strobed continuous laser illumination, or more recently, pulsed laser illumination, have lately created the possibility to bring the holographic testing approach to the level of industrial applicability for modal analysis procedures. The present paper discusses the various critical elements of a holographic ESPI modal testing system.

Recently, during the course of different experimental problem-solving activities on automotive vehicles, several examples have been found in which the identification of the cause of a particular vibration problem related to a specific component or subsystem involves detecting the presence of an impulsive effect on measured time signals. The difficulty in identifying such an effect arises due to the fact that the vibrational response signals measured during operation are dominated by relatively high amplitude harmonics which tend to mask the impulsive component. This article describes two case studies for this type of identification problem, a servo-assisted steering system and a front suspension shock absorber strut.

The DIANA project aims studying “Development & Integration of a Unified Approach for Structure Borne Noise Analysis”. The project was led by LMS Engineering (Belgium) which collaborated with the research centres of FIAT (CRF, Italy) and Renault (RNUR-DE, France). Other members in the consortium were MIRA (UK) and the Technical University of Bielefeld. Ford Germany acted as sponsor and provided testvehicles. The first objective of the project included the investigation of advantages, disadvantages, sensitivity to boundary conditions and limits of confidence of several classical techniques in the field of structure borne noise analysis. These techniques were amongst others: single input transfer path analysis, principal component analysis and mount testing. At the other hand new techniques have also been elaborated. They were related to algorithms for indirect force determination, tire domain principal component analysis and advanced mount testing.