Forming of monoaxially curved thin-walled T-section integral panels by double-sided laser peening

Abstract

Thin-walled T-section integral panels are widely used in the aerospace industry for achieving lightweight and high performance, but their strict manufacturing requirements present challenges to current forming processes. This study proposes the double-sided laser peening (DSLP) process and develops corresponding models to achieve the forming of monoaxially curved T-section integral panels. An eigen-force model is derived to describe deformation behavior and reveal the underlying forming mechanism. The results indicate that bending deformation is driven by the moment originally induced by the in-plane eigen-force deviating from the neutral plane. Full-covered DSLP on the skin results in bending deformation towards the stiffeners, and vice versa. Additionally, DSLP on complementary regions induces identical bending deformations in opposite directions. The undesired bending distortion appeared in single-sided laser peening is eliminated by DSLP, as the action point of the eigen-force migrates to the neutral plane of the skin or stiffeners after DSLP, thereby preventing the generation of bending moments. Subsequently, drawing inspirations from topology optimization methods, a customized process planning model is developed for DSLP of monoaxially curved T-section panels. The globally convergent method of moving asymptotes is applied to solve the process planning model. The formed T-section panels, guided by the solution of the process planning model, exhibit good consistency with the objective shape. By unleashing the potential of double-sided laser peening in driving bending, this study provides a novel strategy for forming large-scale complex panels with stiffeners.