To ensure dynamic requirements of technical systems, methods like the finite element method (FEM) are successfully applied. For large structures as ship geometries, such analyses in the acoustic-relevant frequency range are usually not used productively. Highly time consuming investigations are incompatible to the generally single-unit production and short conception phases in ship design. The energy finite element method (EFEM) is a grid-based approach, which has the potential to provide a technique for the evaluation of acoustic characteristics even for major and complex structures at high frequencies. The less time consuming calculations generally result from a smaller number of degrees of freedom at the nodes and, in particular, it is feasible to use coarser grids than in the FEM. The governing equations are similar to that of the static heat conduction. State variables are the time and locally space averaged energy densities of the different wave types. The main focus is on the coupling— not only between the structure and the fluid, but also at junctions within the structure. Preliminary investigations on the reliability of EFEM results will be presented, questioning if the approach is applicable to operative ship design. [This work was done within the collaborative research project EPES.]
<div class="section abstract"><div class="htmlview paragraph">Along with the increasing importance of battery electric vehicles for the automotive industry, new challenges have emerged in the development process of the acoustic behavior of the electric powertrain. One concern arises from the high-frequency whining noise, either caused by the electric field of the motor or by the gearbox. Noise is transmitted via two different paths, the structure-borne path and the airborne path. The focus here is on the latter one, which describes the radiated sound from the surface of the motor housing and the transmission through the car body to the driver’s ear.</div><div class="htmlview paragraph">One possibility for reducing the effect of this acoustic radiation is the application of passive acoustic noise control treatments. This is typically done either by attaching secondary treatments on the vehicle-body side or by encapsulating the motor directly. Depending on the applied material concept, the motor-mounted encapsulation approach isolates the motor and/or adds absorption to the engine bay.</div><div class="htmlview paragraph">To implement a process for the prediction of the acoustic isolation effect of encapsulation in the early design stage, an investigation has been undertaken where different material concepts are applied to a generic motor housing (GMH). The isolation performance of these encapsulation concepts is evaluated by exciting the housing with an electrodynamic shaker and measuring the radiated sound power. First, the investigation is performed experimentally; afterward, corresponding simulations are validated by test results. Various conclusions can be drawn from this study for certain aspects of the process and the simulation model.</div></div>
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