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Noise-vibration-harshness (NVH) is now playing an important role in electric vehicle development process. Experience shows that the NVH criteria must be considered at the very early stages of the concept design phase. Finite Elements (FE) models are widely used to simulate the vehicle design. To achieve a correct accuracy of a FE model, the results of an experimental modal analysis (EMA) are commonly applied to a FE model via correlation and updating processes. Thus, different kinds of optimization might be used throughout the concept design duration. This paper describes, first, the use of a parametric optimization to tune a FE model in high frequencies relying on the results of the EMA test. Then the frequency response analysis is conducted to detect the critical frequencies for the NVH performance. Based on the results of this analysis, a topographic optimization is performed.

In vibroacoustic, bandgap effects related to periodic and/or locally resonant architectural materials can lead to new types of structural vibration filters. This communication concerns periodic pipes used in industrial context. Such pipes are seen, as architectural structural waveguides in which flexural, torsional, and longitudinal waves can propagate. To control the propagation of these vibrations and reduce their possible noise disturbance, Bragg or resonant band effects can be obtained by architecting the axial variations of the cross-section. As a result, a waveguide can be tuned to create stop bands with bandwidths large enough to make them interesting for industrial applications. For this purpose, dispersion relations are derived and analyzed based on the Floquet method and numerical Finite Element simulations. In many practical cases, all kinds of waves generally coexist due to the inevitable structural couplings.