A lower bound estimate of the critical load for helicopter main rotor composite blade according to the limit equilibrium theory. Analysis results

The results of analyzing the stress-strain and limiting states of a main rotor blade of the Ansat helicopter in the hovering mode are given. To estimate the strength, a technique of elastic constants variation is used; it is based on the limit equilibrium theory and enables us to obtain the upper and lower bounds of the critical load simultaneously. Strength margin coefficients of the blade root section are determined depending on the azimuth of a blade turn, when all generalized forces vary in proportion to one loading parameter.     

Calculation of a safety factor of damaged composite main rotor blade according to limit equilibrium theory

Safety factors of the Ansat helicopter main rotor blade are determined in the root section at various flight modes with taking into account the possible damages.     

A method for determining velocities and accelerations of an elastic main rotor blade element

A refined method is presented for calculating velocities and accelerations of an elastic blade element of a rotorcraft rotor in the general case of its motion with linear and angular velocities and accelerations. The method can be used when calculating aerodynamic and aeroelastic characteristics of main and tail rotors for a wide range of problems in aeromechanics.