Encoding of direct 4D printing of isotropic single-material system for double-curvature and multimodal morphing

TL;DR

This paper introduces a novel single-material 4D printing method that enables the creation of complex, doubly curved 3D shapes from 2D sheets, with shape locking capabilities, using an inverse-design algorithm for precise morphing.

Contribution

It presents the first direct 4D printing technique for isotropic single-material systems to achieve complex 3D shapes with shape locking, using an integrated inverse-design approach.

Findings

Successfully printed and morphed 2D sheets into doubly curved 3D shapes.

Achieved shape locking post-deployment for stable structures.

Developed an inverse-design algorithm for targeted 3D morphing.

Abstract

The ability to morph flat sheets into complex 3D shapes is extremely useful for fast manufacturing and saving materials while also allowing volumetrically efficient storage and shipment and a functional use. Direct 4D printing is a compelling method to morph complex 3D shapes out of as-printed 2D plates. However, most direct 4D printing methods require multi-material systems involving costly machines. Moreover, most works have used an open-cell design for shape shifting by encoding a collection of 1D rib deformations, which cannot remain structurally stable. Here, we demonstrate the direct 4D printing of an isotropic single-material system to morph 2D continuous bilayer plates into doubly curved and multimodal 3D complex shapes whose geometry can also be locked after deployment. We develop an inverse-design algorithm that integrates extrusion-based 3D printing of a single-material system to directly morph a raw printed sheet into complex 3D geometries such as a doubly curved surface with shape locking. Furthermore, our inverse-design tool encodes the localized shape-memory anisotropy during the process, providing the processing conditions for a target 3D morphed geometry. Our approach could be used for conventional extrusion-based 3D printing for various applications including biomedical devices, deployable structures, smart textiles, and pop-up Kirigami structures.