Modeling and Simulation of Sheet Metal Deformation for the Generation of Folded Surfaces

Free-form folded sheet structures represent an emerging class of lightweight systems in which geometric deformation is used to transform planar materials into complex three-dimensional configurations. Although curved folding concepts have been extensively investigated from geometrical and kinematic perspectives, the influence of curved folding path topology on the mechanical response of metallic sheets remains insufficiently quantified. This study presents a numerical investigation of the deformation behaviour of aluminium sheets containing different curved folding path configurations. Three geometrical configurations were analysed: a single curved folding path, two intersecting curved folding paths and three intersecting curved folding paths. Five sheet thicknesses were evaluated under a uniform in-plane edge pressure of 10 MPa. All models were developed using a parametric CAD approach and analysed under identical material properties, geometrical dimensions, and loading conditions in order to isolate the influence of folding topology. The effects of sheet thickness and boundary condition definition were investigated using complementary numerical approaches based on Altair SimSolid and Altair HyperMesh. The results obtained for displacements and Von Mises stress are strongly dependent on the overall configuration and sheet thickness. Mathematical regression models Dmax(C,t) and smax(C,t) were established to express global displacement and Von Mises equivalent stress as quadratic functions of folding topology (C) and thickness (t). However, additional intersecting folding paths generate higher local stress concentrations, particularly in regions where multiple deformation mechanisms interact. The study also highlights the importance of boundary condition definition in predicting the deformation behaviour of curved folded structures. Fully constrained folding paths may introduce artificial stress concentrations, while localized and distributed constraints provide a more realistic representation of the physical deformation mechanism. The results establish a systematic relationship between curved folding topology, structural stiffness, stress distribution, and constraint definition. The proposed methodology can support the design and optimization of lightweight free-form folded structures for mechanical engineering, architectural, and industrial applications.