VIBRATION ANALYSIS OF TWISTED PLATES.

The trends of variation of first five frequencies of low aspect ratio cantilever plates with pre-twist angle have been studied using three dimensional elements as well as shell elements. Both the analyses agree as far as the trend of variation is considered. However the frequencies obtained using three-dimensional approach are slightly higher in the case of fundamental mode and in the other cases they are lower compared with the analysis using shell elements. First flap-wise bending, frequency and the first edgewise bending frequency have a decreasing trend while the other higher mode frequencies have an increasing trend. Except for the first mode frequency all the higher mode frequencies are sensitive to thickness variation particularly the torsional mode frequencies, when the plate is twisted.