High Frequency Response of a Stiffened Box Structure.
Abstract
Power Flow Finite Element Analysis (PFFEA) has been wider development at Defence Research Establishment Atlantic (DREA) in support of the Ship Noise Project. PFFEA is an analysis method for predicting high frequency structural acoustic and vibration response. The method is based on a vibrational conductivity approach in which the flow of vibrational energy is modelled in a similar fashion to heat conduction with convective losses. This report discusses experiments performed with DREA's ship tank test model to assist in the validation of the PFFEA software for high frequency structural vibrations. The experiments involved excitation of the steel box structure at relatively high frequencies using an electromagnetic shaker driving either the centre plate of the test model or one of three typical plate intersections (a symmetric and unsymmetric T-plate junction and an L-plate junction) making up the structure. Both the input mobility to and the response of the test model were measured under broadband excitation using an accelerometer. The input mobilities predicted by the PFFEA code compared extremely well with the experimental measurements. While the power flow method is unable to accurately predict modal response (in this case frequencies up to about 3 kHz), the model accurately predicted the average behaviour for all four cases. When looking at the response of the ship tank panels, in general, the PFFEA program was able to predict the amplitude of the transfer mobility with some degree of accuracy. However, there were significant variations in amplitude with frequency in the measured data which were not modelled with the PFFEA code. As a result, the PFFEA program should primarily be used when predictions are required over a band of frequencies rather than in support of a harmonic analysis.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1998
- Accession Number
- ADA362052
Entities
People
- Layton E. Gilroy
- Malcolm J. Smith