Irreversible deformation of architected structures

Creating a curved surface from a flat membrane has recently been made possible by architected materials. Kinematic incompatibilities of non-uniform cutting patterns generate out-of-plane displacements. The resulting deformed geometry closely matches a target shape using expansion mapping techniques between the initial and final shapes. In this work, we introduce the use of irreversible plastic deformation as a means to hold the target shape. We use numerical homogenization using finite element methods to predict the kinematics and mechanical response of the architected structure. We propose a reduced model of torsional hinges to capture the elastoplastic deformation of the structure and program the target geometry and mechanical response of the deformed structure. Finally we validate our approach experimentally and program surfaces that are mechanically functional and created using a simple actuation mechanism.