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Transient Process' Sensitivity for Turbo-Generator Supporting Structure with Regard to Parametric Excitation

Z. Wójcicki
Organization: Institute of Civil Engineering
Department: Wroclaw University of Technology
Journal / Anthology

Zeitschrift Fur Angewandte Mathematik Und Mechanik
Year: 2001
Volume: 81
Page range: S237-S238

This paper is a continuation of the research presented in GAMM'98 and GAMM'99, where the problem of a lateral parametric vibration of the steel, spatial, orthogonal frame supporting small turbo-generator structure was carried out. One column, Fig. 1, was extracted from the original structure. Dimensions, stiffness and mass parameters of the strut are the same as in the structure but rotary inertia of mass element at the top of the column and rotary stuffness of spring supporting the column were chosen to fit particular eigenvalue of the original structure. They dynamic instability region in the frequency range 6-10 Hz was observed, despite the fact that the magnitude of the whole axial force was only about 30% of the Euler's critical value for the column. Since the work regime of the turbo-generator is 50 Hz, the transient process should be examined. It is even more necessary because of the fact that the 2nd eigenvalue for turbo-generator structure is 6,86 Hz but the 1st eigenvalue for the column is 3,14 Hz. Thus the proportion between them is about 2. It corresponds to the first - the most important - parametric resonance area. The paper concerns the analysis of the transient process and transient process' sensitivity for turbo-generator supporting structure with consideration of the parametric effects. The "overshoot (peak response) sensitivity" method in time domain [1], was adopted to dirst order sensitivity analysis of the parametric non-periodic systems. The FEM is used to solve the dynamic model. Numerical and analytical calculations are supported by the computer system "Mathematica", "COSMOS/M" as well as author's software.

*Engineering > Mechanical and Structural Engineering