Closed-loop shot peen forming with in-process measurement and optimization

Abstract

Shot peen forming is relied upon in the aerospace manufacturing industry to form thin metal panels into complex geometries. The accuracy and repeatability of the process depend on the initial stress state of the part. The measurement of residual stresses being costly or destructive leaves the field in want of a more efficient method to produce accurate parts. This work proposes a closed-loop method, based on in-process measurements, a finite element model, and optimization to reduce shot peen forming errors by iterative replanning. We demonstrate in an experimental test case of three sample plates that the proposed method can reduce the forming error below 0.2 mm, while the standard open-loop planning yielded errors from 0.333 mm to 0.667 mm, for samples of 1.04 mm thickness.