COBEM99

S21 Vibrações e Análise Modal

Title:

CORRELATION OF MODE SHAPES AND DEGREES OF FREEDOM OF MODELS OBTAINED BY FINITE ELEMENT AND EXPERIMENTAL MODAL ANALYSIS

Summary :

ABSTRACT. THE VERIFICATION OF THE QUALITY OF A DYNAMIC MODEL FOR A STRUCTURE OBTAINED BY THE FINITE ELEMENT METHOD BEGINS THROUGH A CORRELATION BETWEEN THE MODAL PARAMETERS OF THIS MODEL AND THE MODAL PARAMETERS OBTAINED BY EXPERIMENTAL MODAL ANALYSIS. THE CORRELATION BETWEEN THE MODE SHAPES (MODAL VECTORS) OF THE TWO MODELS (NUMERIC AND EXPERIMENTAL) PROVIDES A GLOBAL INDICATION OF THEIR SIMILARITY LEVEL, WHILE THE CORRELATION BETWEEN THE DEGREES OF FREEDOM PROVIDES AN INDICATION OF THE CONTRIBUTION OF EACH DEGREE OF FREEDOM TO THE GLOBAL VALUES OF THE CORRELATION BETWEEN THE MODAL VECTORS. THIS WORK PRESENTS APPLICATION RESULTS OF SOME TECHNIQUES OF CORRELATION OF MODE SHAPES AND DEGREES OF FREEDOM. THE TECHNIQUES USED FOR THE CORRELATION BETWEEN THE MODE SHAPES ARE MAC, MSF AND POC, WHILE FOR CORRELATION AMONG DEGREES OF FREEDOM COMAC AND MODULUS DIFFERENCE ARE USED. THE VERIFICATION OF THE CORRELATION, THROUGH THESE TECHNIQUES IS ACCOMPLISHED WITHOUT USING THE MASS AND STIFFNESS MATRICES OF THE FINITE ELEMENT MODEL. THE TECHNIQUES ARE APPLIED IN RESULTS FOR A FREE-FREE STEEL BEAM, WHERE IN THE MODAL TEST, EXCITATION BY IMPACT IS USED. KEYWORDS: MODAL ANALYSIS, MODE SHAPES, MODAL VECTORS, DEGREES OF FREEDOM, CORRELATION.

Author :

Mesquita, Alexandre Luiz A.
Varoto, Paulo Sergio

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