Date of Award

Summer 1983

Document Type

Thesis

Department

Mechanical & Aerospace Engineering

Program/Concentration

Engineering Mechanics

Committee Director

Samir R. Ibrahim

Committee Member

Chub Mei

Committee Member

Jeffrey Kelly

Call Number for Print

Special Collections; LD4331.E57L54

Abstract

In the past, normal modes approximation to complex modes was employed by most researchers or users in the process of identification or modification of structural systems. This is true, of course for simple structures with no or proportional damping. For complex structures with nonproportional damping, even level of which is small, it will be shown that applying this approximation is inadequate. Use of complex modes instead of approximated normal modes is justified.

An algorithm is presented that computes a set of normal modes from the corresponding measured complex modes. The computed normal modes are then used in the Berman's technique to improve an analytical approximated mass matrix. A numerical experiment is conducted to validate the proposed theory. Results show that the use of computed normal modes in the correction procedure produces better improvements in the mass matrix than the use of approximated ones if complex modes exist in the measured range.

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DOI

10.25777/0d1v-kp56

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