Influence of perforation damage position on composite blade vibration characteristics

Finite element model of a helicopter whole rotor blade was established through ANSYS software. The relation between vibration characteristics and damage position was obtained by simulating perforation damage at different locations in the blade spanwise and chordwise directions. And comparison was carried out with that of the undamaged blade. The effect of different perforation locations on vibration performance was analyzed. The results show that damage cannot induce the change of vibration generally but affects vibration frequencies. The effect on vibration frequencies not only relates with the damage locations but also with the damage degree of major structures. The damage at blade root influences the whole vibration frequencies obviously, while the damage in the leading and trailing edge affect lag frequencies greatest. The damage in the wing box has maximum affect on the twist frequencies. The larger the damage in the trailing-edge strip and the main beam is, the greater the effect of lag frequencies is. The relation between twist wrap, spar and inner twist wrap in the main beam with the twist frequencies is the same with the lag vibration.