
Accession Number : AD0679571
Title : NORMAL MODE THEORY FOR COMBINED STRUCTURES,
Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C
Personal Author(s) : Fourney,William L. ; O'Hara,George J.
Report Date : 24 OCT 1968
Pagination or Media Count : 20
Abstract : This report considers a linear elastic structure to consist of several parts; a primary structure which has a rigid base, and one or more substructures which are firmly attached to the primary structure. The normal modes and natural frequencies of the combined structure are determined from a knowledge of the primary structure's normal modes and frequencies and the mass and the elastic constants distribution of the secondary structure. The displacements of the total structure are expressed as a series expansion of the scaled normal modes of the primary structure alone, and a set of equations is used to find the normal coordinates of the secondary structures for the new natural frequencies. There is in general an increase in the number of degrees of freedom. The scaling factors involved are determined from the equilibrium equations of the primary structure, with the secondary structures removed and replaced by their internal forces of connection. Numerical examples are presented. (Author)
Descriptors : (*ELASTIC SHELLS, LOADS(FORCES)), STRUCTURAL PROPERTIES, DYNAMICS, EQUATIONS OF MOTION, INTEGRAL TRANSFORMS, PARTIAL DIFFERENTIAL EQUATIONS, MATRICES(MATHEMATICS), FORCE(MECHANICS)
Subject Categories : Structural Engineering and Building Technology
Mechanics
Distribution Statement : APPROVED FOR PUBLIC RELEASE