Strength analysis of composite rotor helicopter blade, having percussive damage, by limit equilibrium theory

Authors model the limiting state of the helicopter «ANSAT» rotor blade at different flight modes, taking into account the possible damage to the blade in the butt section. The method of variation of elastic constants, based on the limit equilibrium theory and allowing to obtain both upper and lower limits of the limit load, is used to estimate the strength. The stresses in the layers determined in accordance with the deformation law of the associated limit yield surface of these layers, are expressed in terms of the six-dimensional vector of generalized forces. Analysis of the limit stress state is reduced to the analysis of the limit state in the space of the generalized forces. The safety factors of the blade's butt section depending on the azimuth angle of rotation of the blade are determined for the case when all the generalized forces are proportional to one loading parameter. The possibility of making internal diagnostics of damage areas using x-ray computer tomography is announced. It is proposed to use medical Siemens x-ray tomograph to perform such diagnostics.