A Method for Determining the Approximate Resonance Frequency of a Structure Surrounded by a Compressible Fluid.
Abstract
A method for determining the approximate resonance frequency of a structure surrounded by a compressible fluid includes the steps of: (1) performing an in-vacuo eigenvalue analysis to determine in-vacuo frequencies and mode shapes of the structure; (2) selecting one of the mode shapes as an in-vacuo mode of interest, (3) computing an influence matrix at the eigenfrequency of the selected mode of interest; (4) combining the computed influence matrix with structural stiffness and mass matrices from a finite element program, and using the modified matrices computing eigenvalues of the structure, including eigenvectors; (5) selecting from the computed eigenvectors a computed mode having substantially the same displaced shape as the in-vacuo mode of interest; (6) determining the eigenfrequency of the selected computed mode; (7) determining any difference between the computed eigenfrequency of the selected computed mode and the in-vacuo eigenfrequency of the selected in-vacuo mode of interest; wherein (8) if the difference is equal to, or less than, a selected tolerance, the computed eigenfrequency of the computed mode is the approximate resonance frequency of the structure; and (9) if the difference is greater than the tolerance, repeating step (3) substituting the computed eigenfrequency of the selected computed mode for the in-vacuo eigenfrequency for the in-vacuo mode of interest, and thereafter, repeating steps (4) - (9), substituting in step (3) a most recent computed eigenfrequency of the selected computed mode for the previously used computed eigenfrequency of the selected computed mode.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 15, 1996
- Accession Number
- ADD018052
Entities
People
- Clementina M. Siders
- Michele D. Mccollum
Organizations
- United States Department of the Navy