Numerical Predictions for the Demo Enclosure and Comparison to Experiment

The ''demo enclosure'' is a small box meant to simulate the basic characteristics of an equipment enclosure, but without the complexity of an actual enclosure. Extensive experimental measurements have been made on the enclosure and are summarized in a companion report entitled ''Experimental Measurements of the Demo Enclosure''. In this report, we will summarize the associated numerical modeling of the enclosure's structural vibration and radiated sound field using finite and boundary element techniques. One of the main goals of the report is to establish useful modeling guidelines for finite and boundary element analyses of enclosures. Producing accurate predictions is of primary importance, but ease of implementation is also important. We will try to demonstrate that it is not always beneficial to try to duplicate all the enclosure's structural complexity in the finite and boundary element models because errors inevitably occur and it is frequently difficult to adjust the models without considerable effort. For example, it is relatively simple to produce accurate models for shelves and enclosures separately, but their interconnections are much more difficult to represent. When the models are combined into much larger finite element models, it becomes difficult and time consuming to optimize the modeling of the interconnections. Our research was thus directed towards developing simple methods for adjusting the individual models and combining them together after an initial unite element analysis