Calculation methods of investigating the surface layer of thin-walled shafts hardened by methods of surface plastic deformation

Calculation methods of investigating the residual stress-strain state of the surface layer of shafts hardened by shot peening and diamond burnishing are discussed in the paper. Shafts manufactured at aircraft plants are mostly thin-walled. In addition high requirements are imposed on the accuracy of their geometric dimensions and shape. Ensuring the fatigue resistance of shafts is achieved by applying hardening treatment. Hardening treatment residual stresses result in residual deformation of shafts often exceeding manufacturing tolerances. The models and approaches proposed in this paper make it possible to predict computationally the residual stress-strain state of the surface layer after diamond burnishing as well as technological residual deformations of the shafts caused by residual stress. They also allow adjusting the modes of shot peening and diamond burnishing at the stage of process development. The work was carried out for a shaft made of VT-22 and EP517-SH materials. The results of the investigation show that the use of preliminary numerical analysis of treatment modes makes it possible to ensure residual deformations of the most critical sections of the shafts and seating surfaces for bearings within manufacturing tolerances and also to reduce tensile residual stress on the shaft surface after diamond burnishing.