Simulations and predictions of the vibro-acoustic behavior of engines are primary interest objectives in the automotive industry. Particularly, we are interested here in a large frequency domain ([0,6000] Hz). When considering the linear vibrations of engine components in such a medium-frequency range, classical damping assumptions are no longer valid. Thus, numerical simulations may have to deal with some viscoelastic components and (very) large finite element models, which lead to prohibitive CPU times. The aim of the study is then to make these simulations feasible. First, we present in this paper the example of an engine front cover, whose viscoelastic behavior has been measured and taken into account via a simple rheological model. Assuming that this component is homogeneous, its frequency response functions are then computed using a modified modal method and compared with the experimental FRF performed inside this frequency range. Second, we describe a Component Mode Synthesis procedure which allows non-classical damping and where reduced problems are solved using an iterative algorithm. Numerical applications are given for the case of assembled engine components, involving tens of thousands of dof.
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