Session: S-03 Novel Structural Concepts
Paper Number: 171882
171882 - Mechanical Memory in Structural Morphing Surfaces
We present two-dimensional multistable structural units based on triangular, rectangular, and hexagonal footprints, composed of flexible arches bonded to flat bases. Each unit is designed to undergo snap-through buckling. When arranged in tiled arrays, these units enable to create shape-morphing surfaces capable of complex, programmable deformations. The global morphing behavior is determined by the local design of each unit and the spanning sequence in the array, offering high tunability and spatial control of surface reconfiguration. This modular approach lays the foundation for adaptive structural systems that respond mechanically to external stimuli.
Fabrication begins with laser cutting of PETG sheets to form both arch and base strips. To eliminate prestress and ensure flatness in the base, the arch strips are thermally formed into sinusoidal shapes using 3D-printed molds. The shaped arches are then cooled and bonded to the base strips using adhesive, completing the assembly of bistable units. A critical aspect of this process is the heat treatment step: improper heating or premature removal from the mold can lead to unwanted camber or uneven surfaces in the final specimens.
We characterize the mechanical behavior of these units through displacement-controlled compression experiments using a universal testing machine. By applying vertical displacements at a controlled rate to the apex of the sinusoidal arches, we capture the force-displacement response of each specimen in quasi-static testing protocol. We observe nonlinear mechanical behavior associated with snap-through force-deformation response. We also perform compression tests on arrays of these units to investigate the interaction among units when snapped.
To simulate and analyze the response of individual units and their interactions within arrays, we employ the Discrete Elastic Rods (DER) method—a reduced-order modeling framework that efficiently captures the large-deformation mechanics of slender structures. Comparison with experimental results confirms the fidelity of the DER approach in reproducing both the force-deformation responses obtained from compression tests and deformed shapes obtained from 3D scan. This multi-method analysis confirms the robustness of the DER model for capturing the complex behaviors of these multistable systems.
Our study reveals that the multistability inherent to these units encodes a form of mechanical memory—each stable state can represent a stored configuration that persists in the absence of continuous external input. This property enables the implementation of mechanologic, a paradigm akin to digital logic but operating in the mechanical domain. By designing unit interactions and transitions carefully, one can construct arrays that perform mechanical logic operations, which opens new directions for adaptive structures and intelligent systems in the mechanical domain.
Presenting Author: Asifur Rahman Stony Brook University
Presenting Author Biography: Asifur Rahman is a senior PhD student and Graduate Research Assistant in the Department of Civil Engineering in the Stony Brook University, specializing in shape morphing structural systems.
Mechanical Memory in Structural Morphing Surfaces
Paper Type
Technical Presentation Only