A COMBINED FINITE ELEMENT-TRANSFER MATRIX METHOD FOR THE THEORETICAL EVALUATION OF FREE VIBRATIONS OF PRETWISTED-TURBOMACHINERY BLADES

摘要

The prediction of coupled natural frequencies of turbomachinery blading is very important for preventing possible damages of the blades with consequent failure or shutdown of the whole machine. In this paper a proposal for the evaluation of these frequencies, which jointy use the finite element and the transfer matrix methods is presented; the advantages of this procedure, thoroughly explained in a former paper, are in particular the following: 1) possibility of high precision; 2) computation time and memory requirements restricted; 3) possibility of well representing the contraint conditions at the blade's root. The theoretical values of the calculated frequencies are compared with those of experimental results and other proposed methods, and are shown to be in a favorable agreement with them.