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.