Traditionally, engineers avoid residual stresses in manufacturing because residual stresses can lead to undesired geometric distortions and a loss of strength and stiffness. On the other hand, nature astutely exploits residual stresses to create complex morphologies. For example, residual stresses induced from in-plane differential growth have been identified as a key mechanism in fractal rippling at the edges of leaves [2] and the blooming of flowers [1]. Here, we demonstrate the feasibility of creating complex 3D geometries (non-developable surfaces) from 2D developable surfaces by tailoring residual stresses during manufacturing, with a focus on tow-steered fibre-reinforced composite materials. Fibre-reinforced composite materials have orthotropic properties (thermal expansion factors and Young’s modulus) and by smoothly blending the fibre direction along curvilinear trajectories, tailored in-plane residual stress distributions can be induced during post-cure cooling that then lead to a target shape through a loss of stability of the developable metric. An in-house nonlinear FE solver with extended stability capabilities (bifurcation pinpointing and branch switching) is adopted to simulate the manufacturing process of three benchmark structures, i.e. a rectangular strip (to mimic the rippling at the edge of a leaf), a cylindrical shell (to mimic the edge wrinkling pattern in a daffodil), and a doubly curved thin elastic shell (to mimic the curvature reversal in a blooming lily). We also demonstrate the multi-stability of the manufactured morphologies, which can potentially be exploited for shape-shifting purposes. The present work sheds light on manufacturing complex geometries by precisely tailoring in-plane residual stress distributions.References[1] H. Liang and L. Mahadevan. “Growth, geometry, and mechanics of a bloom- ing lily”. In: Proceedings of the National Academy of Sciences of the United States of America 108.14 (2011), pp. 5516–5521. issn: 10916490.[2] H. Liang and L. Mahadevan. “The shape of a long leaf”. In: Proceedings of the National Academy of Sciences of the United States of America 106.14 (2009), pp. 5516–5521. issn: 10916490
