Study on Contact Stress Distribution at Curvic Couplings Fitting Surface under Pretightening Force

The curvic coupling configuration serves as a foundational element for the joining and torque transmission of aero-engine rotors. The uneven contact stress distribution at its fitting surface can cause tooth surface wear and failure, which in turn leads to the vibration of the entire engine. The curvic couplings are fixed by the pretightening force. The pretightening force greatly influences the contact stress distribution characteristics at the fitting surface. The influence of the pretightening sequence and times on the contact stress distribution characteristics under pretightening force is analyzed in this paper. To reduce the non-uniformity of the contact stress profile, a pretightening force correction model under different pretightening conditions was established. The impacts of the pretightening forces before and after correction on the homogeneity of the contact stress profile were compared. The results show that multi-time pretightening and an appropriate pretightening sequence improve the contact stress profile characteristics. Applying the corrected pretightening force significantly reduces the non-uniformity of the contact stress profile. Specifically, applying the corrected pretightening force multiple times in sequence is effective in further reducing the dispersion of contact stress distribution at the fitting surface. Pretightening in a diagonal sequence is more efficient in improving the homogeneity of contact stress. The research will contribute to precision manufacturing as well as the regulation of aero-engine rotor systems.