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Despite the fact that Transfer Path Analysis (TPA) is a well known and widely used NVH tool it still has some hindrances, the most significant being the huge measurement time to build the full data model. For this reason the industry is constantly seeking for faster methods. The core concepts of a novel TPA approach have already been published in a paper at the ISMA 2008 Conference in Leuven, Belgium. The key idea of the method is the use of parametric models for the estimation of loads. These parameters are frequency independent as opposed to e.g. the classical inverse force identification method where the loads have to be calculated separately for each frequency step. This makes the method scalable, enabling the engineer to use a simpler model based on a small amount of measurement data for quick troubleshooting or simply increase accuracy by a few additional measurements and using a more complex model.

Since its first publication in the beginning of the eighties, Transfer Path Analysis (TPA) has evolved into a widely used tool for noise and vibration troubleshooting and internal load estimation, and this for single source as well as multivariate problems. One of the main bottlenecks preventing its even more widespread use in the actual vehicle development process is the test time to build the full data model, requiring not only in-operation tests but also extensive Frequency Response Function tests. As a consequence, several new approaches have appeared over the past years attempting to circumvent this limitation, such as Fast and Multilevel TPA and Operational TPA. The latter method attracts quite some attention as it only requires operational data measured at the path references and target locations.

15 years of NVH applications make Transfer Path Analysis (TPA) appear a commodity tool. But despite the fact that TPA is today successfully used in a large variety of applications in automotive and mechanical industries, its main bottleneck remains the huge measurement time to build the full TPA model. This paper presents a new TPA method that provides a good compromise between path accuracy and measurement time. The method is also referred to as OPAX. The key idea of OPAX is the use of simplified parametric load models with limited number of model parameters. The main advantage of this is that one should measure only a small amount of FRF data to identify the operational loads. This drastically reduces measurement time and efforts. In addition to this, the OPAX method does not require mount stiffness data and allows a simultaneous identification of structural and acoustic paths.

Aircraft noise modeling aims to provide designers with computational tools that allow exploring the design parameters domain early in the design and development process. A number of modeling techniques are available for acoustics and vibration prediction, but in order to define objective targets for sound quality perception, dedicated tools are still needed to correlate structural models and design modifications with human perception of sounds. This paper presents a model-based sound synthesis concept for interior and exterior aircraft noise that allows interactive, real-time sound reproduction and replay. The proposed approach is presented through two application cases: jet flyover noise and turboprop interior noise.

A key issue in noise emission studies of noise producing machinery concerns the identification and analysis of the noise sources and their interaction and radiation into the far field. This paper presents a new acoustic measurement technique for noise source identification in stationary applications. The core of the technology is a handheld measurement instrument combining a position and orientation tracking device with a 3D sound intensity probe. The technique allows an on-line 3D visualization of the sound field while moving the probe freely around the test object. By focusing on the areas of interest, troublesome areas can be identified that require further in-depth analysis. The measurement technique is flexible, interactive and widely applicable in industrial applications. This paper explains the working principle and characteristics of this new technology and positions it to existing methods like traditional sound intensity testing and array techniques.

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).