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A vehicle concept finite-element model is experimentally assessed for predicting structural vibration to 50 Hz. The vehicle concept model represents the body structure with a coarse mesh of plate and beam elements, while the suspension and powertrain are modeled with a coarse mesh of rigid-links, beams, and lumped mass, damping, and stiffness elements. Comparisons are made between the predicted and measured frequency-response-functions (FRFs) and modes of (a) the body-in-white, (b) the trimmed body, and (c) the full vehicle. For the full vehicle, the comparisons are with a comprehensive set of measured FRFs from 63 tests of nominally identical vehicles that demonstrate the vehicle-to-vehicle variability of the measured FRF response.

A traditional beam-type finite-element model of the automobile exhaust system is shown to only be accurate in predicting the low-frequency rigid-body motion of the exhaust system on the support hangers. The beam-element model is then modified to account for the cross-sectional deformation of the exhaust pipes and is shown to accurately predict the bending vibration up to 300 Hz. The theoretical modification of the beam element model to account for the cross-sectional deformation is described in this paper. Experimental modal analysis tests of an exhaust system installed on a vehicle are conducted to obtain the measured vibration response for experimentally evaluating the accuracy of the model.

An engine system finite-element model is developed and experimentally evaluated for predicting the structural vibration and radiated noise of the running engine. Combustion and inertial loads from a rigid-body dynamic analysis of the crank-piston motion are applied as operating loads in the model. Comparisons are made with measurements of the structural vibration and radiated noise of a running engine. The comparisons show that the accuracy of the model in predicting structural vibration and radiated noise is generally adequate.

Low-frequency interior noise in the automobile passenger compartment can be significantly affected by the vibration behavior of the body panels which surround the enclosed cavity. This paper reviews a finite element method for computing panel-excited interior noise and outlines an approach for identifying potentially noisy panels adjacent to the passenger compartment. To illustrate the potential of the analytical method, it is applied to a production automobile. A structural modification suggested by the procedure is shown to significantly reduce the low-frequency interior noise to which the occupant is exposed. Experimental verification of the method is presented.

A coupled engine-block and crankshaft model is developed and applied to predict the engine block vibration and radiated noise. Block surface vibration which is excited by combustion pulses and inertia loads is investigated as the source of radiated noise. The predicted response shows the dominant engine harmonics, resonant frequencies, global modes and local surfaces which participate to produce the radiated noise. A structural modification is evaluated which reduces the transmission of the loads through the bulkheads, and significant vibration and noise reduction is predicted.

A structural-acoustic finite-element model of an automobile trimmed-body is developed and experimentally evaluated for predicting body vibration and interior noise for frequencies up to 200 Hz. The structural-acoustic model is developed by coupling finite element models of trimmed-body structure and the passenger-compartment acoustic cavity. Frequency-response-function measurements of the structural vibration and interior acoustic response for shaker excitation of a trimmed body are used to assess the accuracy of the structural-acoustic model.