Patent ID: 8294059

Claim:
A process of producing multiple through-holes in an acoustic skin of an acoustic panel, the process comprising: deforming a sheet member to have an arcuate shape with an arcuate surface; mounting, orienting, translating and rotating the arcuate-shaped sheet member on a mandrel relative to an electron beam gun; operating a multiple-axis positioning drive system to determine orientation, translation and rotation of the arcuate-shaped sheet member relative to the electron beam gun; and then while rotating the arcuate-shaped sheet member, operating the electron beam gun to direct an electron beam at the arcuate surface of the rotating arcuate-shaped sheet member and deflecting the electron beam toward multiple locations on the arcuate surface to produce the multiple through-holes through the arcuate-shaped sheet member in a defined hole pattern and thereby yield a perforated arcuate-shaped acoustic skin having an arcuate flow path surface defined by the arcuate surface of the arcuate-shaped sheet member, the orientation, translation and rotation of the arcuate-shaped sheet member being controlled so that each of the holes has an axis substantially normal to the arcuate flow path surface of the perforated arcuate-shaped acoustic skin sheet and along a radial of a curvature of the perforated arcuate-shaped acoustic skin, and the orientation, translation and rotation of the arcuate-shaped sheet member being further controlled so that the size, shape and spacing of the holes are intentionally altered within the hole pattern to tune at least one specific area of the arcuate flow path surface to attenuate specific frequency bands of noise with the perforated arcuate-shaped acoustic skin.