Vibration performance of composite blade segment with a perforation damage

Damage tolerance analysis and design are usually needed for modern helicopter rotor blades, while the influence of damage on the vibration performance of rotor blade structures is an important aspect. Vibration performance analysis was carried out here by the finite element method for a selected segment of helicopter composite blades with a perforation damage. Comparison of the result was performed with that of the blade segment without damage. The effect of the size and location of the perforation on vibration performance was obtained. The results show that the vibration modes of the rotating blade segment are the same with those of the still segment, while all the vibration frequencies have increased. The damage on the blade segment is more serious when the perforation size is greater. But the perforation damage does not change the modes of the blade segment, and the vibration frequency variations are small. The frequency variation depends on the perforation location. The perforations located in the blade segment root or front edge of the blade section have greater effect on the vibration frequencies of the blade segment.