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Vehicle consumers are becoming more and more insightful and watchful, design alone is not anymore the main factor of differentiation. Generally, they evaluate and compare different models searching for the best cost benefit package, wherein acoustical comfort is an important requirement in the decision. The OEM’s, on the other hand, unceasingly search to identify these requirements so that they`re taken into account in the process of conception of new models. They consider countless information, ranging from the perception of the consumers and information from satisfaction research up to comparative analysis data between competing models (benchmarking), thus defining what’s called targets of the project. In order to realize benchmarking analysis in the NVH field, dozens of operational and laboratory tests are realized, generating hundreds of gigabytes of objective or quantitative data and subjective or qualitative data.

With the purpose to identify the root cause of increased levels of vibration felt at idle speed in a popular vehicle prototype a study was conducted using techniques for analysis of vibration transmission between components of a vehicle, using Mechanical Vibrations Analysis and Operational Modal Analysis, for the analysis of the operational modes was used ODS - Operational Deflection Shape technique which is possible only see the shapes related to probable modes. The experimental results were compared with results for the modal analysis by Finite Element Method (FEM). The vehicles used are identical prototypes, but with different levels of vibration. Therefore, to study there is a vehicle with satisfactory levels and a second with unsatisfactory levels. This study demonstrates the methodology used to identify the cause of the different behaviors between cars and also discuss the improvements made in the body according to the results of the numerical experimental confrontation.

Methodologies of a vehicle assessment through computer simulation comes to enable every day to preview difficulties in developing models, which also contributes to reducing the time to develop a new model. For initial assessment of the vibroacoustic behavior of a vehicle, in the early months of development, the frequency response functions, known as inertance (a/F), are analyzed, at the points of attachment of the engine and suspension to the body still in the Body-in-White configuration. Usually the finite element simulations are performed up to the limit of 300Hz. In the aim at increasing the range of inertance analysis, enabling a more comprehensive analysis in NVH, the results by elements finites simulation were compared, in this work, with the results obtained in experimental measurements focused on the validation of this simulation methodology until the limit of 800Hz.