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Origami-based tunable truss structures for non-volatile mechanical memory operation

Hiromi Yasuda, Tomohiro Tachi, Mia Lee, Jinkyu Yang

arXiv:1702.05402v1cond-mat.mes-hallcond-mat.soft

TL;DR

Mechanical memory devices have mostly been limited to individual one-bit operation, motivating alternatives with broader functionality. This paper studies triangulated cylindrical origami cells and TCO-based truss structures, demonstrating reusable, tailorable mechanical memory operations including one- and two-bit storage.

  • Problem

    Previous mechanical memory devices have mostly operated at the individual one-bit level, while mechanical memory could support electronic/optical functions and broader applications.

  • Method

    The paper analyzes triangulated cylindrical origami cells through energy plots and surface maps, then uses interconnected TCO-based truss structures for mechanical memory operation.

  • Results

    The experiments demonstrate purely mechanical one- and two-bit memory storage mechanisms using TCO-based truss structures.

  • Takeaways & Limitations

    TCO structures provide reusable and tailorable origami-based mechanical memory operations with multi-bit functionality.

  • Takeaways & Limitations

    Because TCO is not a rigid foldable origami, repeated folding and unfolding can warp facets and cause surface fatigue and damage.

Abstract

from arXiv · show

Origami has recently received significant interest from the scientific community as a building block for constructing metamaterials. However, the primary focus has been placed on their kinematic applications, such as deployable space structures and sandwich core materials, by leveraging the compactness and auxeticity of planar origami platforms. Here, we present volumetric origami cells -- specifically triangulated cylindrical origami (TCO) -- with tunable stability and stiffness, and demonstrate their feasibility as non-volatile mechanical memory storage devices. We show that a pair of origami cells can develop a double-well potential to store bit information without the need of residual forces. What makes this origami-based approach more appealing is the realization of two-bit mechanical memory, in which two pairs of TCO cells are interconnected and one pair acts as a control for the other pair. Using TCO-based truss structures, we present an experimental demonstration of purely mechanical one- and two-bit memory storage mechanisms.

Methods

The methods derive TCO folding mechanics from geometry and minimum total potential energy, then fabricate and test truss-based prototypes.

  • Analytical model: TCO crease-line lengths are obtained from the unit-cell geometry, using a modified circumscribing radius and calibrated angle for physical prototypes.The calibrated angle compensates for differences between original and physical prototype models.
  • Analytical model: The total elastic energy is calculated from truss-length changes relative to initial lengths, with k denoting the truss spring constant.The model uses initial lengths a0 and b0 for the two truss families.
  • Analytical model: External work is represented as W = Fu + Tϕ, where F and T are the applied force and torque.The total potential energy combines elastic energy and external work.
  • Analytical model: Equilibrium configurations are obtained by applying the minimum total potential energy principle with respect to displacement u and rotation ϕ.The resulting conditions are ∂Π/∂u = 0 and ∂Π/∂ϕ = 0.
  • Prototype fabrication and testing: Prototype truss structures use laser-cut acrylic polygons, 3D-printed universal joints, stainless-steel shafts, and linear springs.The springs support tension and compression, with stiffness selected according to the prototype model.
  • Prototype fabrication and testing: A customized setup mounts the prototype horizontally while allowing the top surface to translate and rotate with minimal friction during testing.The bottom surface is fixed, and the top surface is supported by a ball bearing and stainless-steel shaft.

Additional information

The authors declare no competing financial interests.

  • The authors declare that they have no competing financial interests.
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