The influence of coriolis force on the natural frequencies of the rotor blades is analysed by the finite element method. We consider the coupling effects of axial and tranvcrse vibration in the rotating plane. An effective algorithm is presented

therefore

comparing with the equation which does not include coriolis force

the number of order of the eigenvalue equation is double

but the requirement for the capacity of the computer is not increase. The numerical results are given for a helicopter rotor blade. The results show that the first few natural frequencies are slight drop

because of coriolis force is considered. The error is less than one percent

if coriolis force is neglected.