Application of Frequency Domain Substructure Synthesis Technique for Plates Loaded with Complex Attachments

Frequency domain substructure synthesis is a modeling technique that enables the prediction of a combined response of individual structures using experimentally measured or numerically predicted frequency response functions (FRFs). The traditional synthesis algorithm [1,2] operates on component impedances and thus generally requires several matrix inversions. An improved algorithm, developed by Jetmundsen et al. [3], requires a single matrix inversion with a completely arbitrary interface definition that can easily incorporate connection impedances. The main limitations of the method are the large data requirements and sensitivity to data truncation. The utility of this technique is demonstrated through a comparison of synthesized and measured admittances of an edge-stiffened plate with attached equipment. The plate mobilities are obtained from a numerical analysis because of the ability to accurately model this structure using a finite element representation. The attachments are characterized experimentally because of their complexity. The sections describe the synthesis technique and show numerical and experimental results for the plate and equipment

Application of Frequency Domain Substructure Synthesis Technique for Plates loaded with Complex Attachments

Frequency domain substructure synthesis is a modeling technique that enables the prediction of a combined response of individual structures using experimentally measured or numerically predicted frequency response functions (FRFs). The traditional synthesis algorithm [1,2] operates on component impedances and thus generally requires several matrix inversions. An improved algorithm, developed by Jetmundsen et al. [3], requires a single matrix inversion with a completely arbitrary interface definition that can easily incorporate connection impedances. The main limitations of the method are the large data requirements and sensitivity to data truncation. The utility of this technique is demonstrated through a comparison of synthesized and measured admittances of an edge-stiffened plate with attached equipment. The plate mobilities are obtained from a numerical analysis because of the ability to accurately model this structure using a finite element representation. The attachments are characterized experimentally because of their complexity. The sections describe the synthesis technique and show numerical and experimental results for the plate and equipment

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

Challenges of Investigating Fluid-Elastic Lock-In of a Shallow Cavity and a Cantilevered Beam at Low Mach Numbers

This report was prepared to talk about Challenges of Investigating Fluid-Elastic Lock-In of a Shallow Cavity and a Cantilevered Beam at Low Mach Number

Experimental Measurements of the Demo Enclosure

The ''demo enclosure'' is a small box constructed at ARL/PSU to simulate the basic characteristics of an equipment enclosure, but without the complexity of an actual enclosure. In the general case, an equipment enclosure can house a variety of electrical equipment, including transformers, card racks, etc., usually mounted on shelves. They are primarily interested in investigating the best way to mount the shelves in the enclosure to mitigate sound radiation due to the excitation from the electrical equipment. A secondary goal is to assess methods for modeling the structural properties of interconnected shelves and cabinets along with the electrical equipment. In this report, they will concentrate on the extensive experimental measurements made during the investigation

Flinovia—flow induced noise and vibration issues and aspects-III

202107 bcvcNot applicableOthersP0002009Published12 month