Vibroacoustic dynamics simulation under centrifugal treatment of helicopter spar pipes

The theoretical studies on noise levels under hardening the surface layers of the helicopter spar pipes through the centrifugal processing are resulted. Spar is considered as a two-point article subjected to the periodic impulse force impact. The calculated relation is obtained for detecting the sound pressure levels at the natural frequencies. The reduced formulas include the geometric, mechanical characteristics, and the hardening processing methods which are set by the amplitude, duration, and impact momentum frequency. It allows determining the noise levels under the centrifugal processing including the design parameters of pieces and the processing conditions. On this basis, the noise level increase values as compared to the admissible limit values in the respective frequency ranges are calculated. This data is essential for the selection and acoustic design of the noise protection at the design stage of the centrifugal processing equipment.