Choosing the Best Functions for the Rayleigh-Ritz Vibration Analysis of Beams

Mochida, Yusuke
Eisenberger, Moshe

EPI International Journal of Engineering
Vol 6 No 1 (2023): Volume 6 Number 1, February 2023

The Rayleigh-Ritz Method is used extensively for the vibration analysis of structures. The accuracy depends on the assumed functions. In this work several different groups of functions are examined and compared for the accuracy of the resulting natural frequencies, and for the overall mode shape error norms calculated with respect to the known exact solutions. It is concluded that a set that combines low order polynomials, odd cosine and odd sine functions, or, even cosine and even sine functions, is more likely to yield the best accuracy and convergence of both frequency and mode shapes for a general beam structure.