VIBRATION AND DAMPING ANALYSIS OF PRETWISTED COMPOSITE BLADES

Vibration characteristics of pre-twisted composite blades are analysed using a three-noded triangular cylindrical shell element. The specifi c example of glass fibre reinforced plastic material is analysed with its material damping. The effect of different parameters such as pre-t wist, fibre orientation, skew angle, taper ratio and aspect ratio on n atural frequency and system loss factor is investigated. It is found t hat the maximum fundamental frequency and maximum fundamental loss fac tor occur at different twist angles and at different fibre orientation s. The influence of taper ratio and aspect ratio on 0-degrees and 90-d egrees fibre orientations is reported. The effect of skew angle on nat ural frequency and on system loss factors is seen to be low.