非対称形ロケット構造振動特性の簡易解析法の研究

概要

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A simplified analytical method is proposed to obtain eigenfrequencies and modes of an asymmetric configuration rocket. The present method is an extension of the symmetric beam element matrix method and can utilize asymmetric beam elements. The purpose of this simplified analysis method using a FORTRAN 77 program is to prepare an analysis tool in the preliminary design phase and a rough-check tool of detailed analysis. This program has three functions: (1) to generate stiffness and mass matrices for the asymmetric beam element with linearly changing sectional properties using the Timoshenko-type beam theory, (2) to calculate the dynamical matrix from which rigid body degrees of freedom are eliminated, and (3) to calculate eigenvalues and eigenvectors. A sample structural vibration analysis of a hypothetical rocket with an asymmetric configuration is conducted to demonstrate the capability of this simplified method. The results obtained agree well with those obtained by MSC/NASTRAN analysis, and this proposed method enables great simplification of model preparation. Based on these findings, the proposed method is judged to be an efficient structural vibration analysis tool of an asymmetric rocket.
1997-08-25