Search for: All records

Yoshimura origami is a classical folding pattern that has inspired many deployable structure designs. Its applications span from space exploration, kinetic architectures and soft robots to even everyday household items. However, despite its wide usage, Yoshimura has been fixated on a set of design constraints to ensure its flat foldability. Through extensive kinematic analysis and prototype tests, this study presents a new Yoshimura that intentionally defies these constraints. Remarkably, one can impart a unique meta-stability by using the Golden Ratio angle ( ${\cot }^{-1}1.618\approx {31.72}^{\circ }$) to define the triangular facets of a generalized Yoshimura (with $n=3$, where $n$is the number of rhombi shapes along its cylindrical circumference). As a result, when its facets are strategically popped out, a ‘Golden Ratio Yoshimura’ boom with $m$modules can be theoretically reconfigured into $8^m$geometrically unique and load-bearing shapes. This result not only challenges the existing design norms but also opens up a new avenue to create deployable and versatile structural systems. This article is part of the theme issue ‘Origami/Kirigami-inspired structures: from fundamentals to applications’. 

Abstract This is a roadmap article with multiple contributors on different aspects of embodying intelligence and computing in the mechanical domain of functional materials and structures. Overall, an IOP roadmap article is a broad, multi-author review with leaders in the field discussing the latest developments, commissioned by the editorial board. The intention here is to cover various topics of adaptive structural and material systems with mechano-intelligence in the overall roadmap, with twelve sections in total. These sections cover topics from materials to devices to systems, such as computational metamaterials, neuromorphic materials, mechanical and material logic, mechanical memory, soft matter computing, physical reservoir computing, wave-based computing, morphological computing, mechanical neural networks, plant-inspired intelligence, pneumatic logic circuits, intelligent robotics, and embodying mechano-intelligence for engineering functionalities via physical computing.  In this paper, we view all the 2-page sections with equal contributions to the overall roadmap article and thus list the authorship on the front page via alphabetical order of their last names.  On the other hand, for each individual section, the authors decide on their own the order of authorship.  

Origami — the ancient art of paper folding — has been widely adopted as a design and fabrication framework for many engineering applications, including multi-functional structures, deployable spacecraft, and architected materials. These applications typically involve complex and dynamic deformations in the origami facets, necessitating high-fidelity models to better simulate folding-induced mechanics and dynamics. This paper presents the formulation and validation of such a new model based on the Absolute Nodal Coordinate Formulation (ANCF), which exploits the tessellated nature of origami and describes it as an assembly of flexible panels rotating around springy creases. To estimate the crease folding, we mathematically formulate a “torsional spring connector” in the framework of ANCF and apply it to the crease nodes, where the facets meshed by ANCF plate elements are interconnected. We simulate the dynamic folding of a Miura-ori unit cell and compare the results with commercial finite element software (ABAQUS) to validate the modeling accuracy. The ANCF model can converge using significantly fewer elements than ABAQUS without sacrificing accuracy. Therefore, this high-fidelity model can help deepen our knowledge of folding-induced mechanics and dynamics, broadening the appeals of origami in science and engineering. 

This study presents a modular, electronics‐free, and fully onboard control and actuation approach for shape memory alloy (SMA)‐based soft robots to achieve locomotion tasks. This approach exploits the nonlinear mechanics of compliant curved beams and carefully designed mechanical control circuits to create and synchronize rhythmic deformation cycles, mimicking the central pattern generators prevalent in animal locomotions. More specifically, the study elucidates a new strategy to amplify the actuation performance of the shape memory coil actuator by coupling it to a carefully designed, monostable curve beam with a snap‐through buckling behavior. Such SMA‐curved beam assembly is integrated with an entirely mechanical circuit featuring a slider mechanism. This circuit can automatically cut off and supply current to the SMA according to its deformation status, generating a self‐sustained rhythmic deformation cycle using a simple DC power supply. Finally, this study presents a new strategy to coordinate (synchronize) two rhythmic deformation cycles from two robotic modules to achieve efficient crawling locomotion but still use a single DC power. This work represents a significant step toward fully autonomous, electronics‐free SMA‐based locomotion robots with fully onboard actuation and control. 

Abstract Bistable composite laminates have exhibited enormous potential in morphing and energy harvesting followed by a wide range of application in aerospace, power generation and automobile industries. This study presents the fatigue analysis of bistable laminates in terms of stiffness degradation and loss of bistability. Moisture saturation of the specimens are ensured by keeping them in a controlled laboratory environment for an extended period of time. Mass of the specimens have been measured to quantify the moisture saturation. Fatigue tests are performed at 1 Hz frequency, and R = −1 stress ratio which is the ratio of minimum stress to maximum stress. Specimens are tested for 3 million cycles in displacement control. Load-displacement plot from the test is divided into 5 stiffness regions. A piecewise study of each region has demonstrated good agreement with existing analytical model. Stiffness degradation in 4 regions corresponding to 2 stable configurations follows general trend for composites up to the second stage of damage in three stage damage progression model while the remaining region corresponding to unstable configuration is not considered in this analysis. Test results have been reproduced with minor discrepancy at the specified environmental and loading condition, ply configuration, and size of the laminate. Test protocols, results, and damage analysis presented in this study can be utilized to evaluate the fatigue performance of multistable CFRP structures subjected to higher amplitudes and frequencies. 

Bistable composite laminates have large-scale applications in morphing and energy-harvesting structures, but their fatigue performance remains largely unexplored. This study investigates the stiffness and damage progression and evaluates bistable performance to develop protocols for long-term applications. We analyze the effects of displacement-controlled fully reversible high cycle fatigue-loading on stiffness, damage, curvature, and snap-through load in the out-of-plane loading direction at eight different combinations of parameters with frequency from 1 to 10 Hz, two boundary conditions, and temperature from 22°C to 150°C up to 3 to 10 million cycles. Stiffness and damage evolution analysis demonstrate the first two stages in out-of-plane fatigue loading. The study proposes a damage definition in terms of load adapting with two fatigue damage models: (1) Shiri Model and (2) Wu Model, while both models exhibit reasonable accuracy in predicting damage for the first two stages despite deviating at the final cycle due to assuming this cycle as the final failure cycle. Of the two models, the Shiri model provided a smaller range of model parameter values, 0.22 and 0.43, for parameters p and q, respectively, which reflects adjustability to different test conditions by maintaining a moderate range. Specimens encountered no final failure by fiber breakage and did not lose bistability for any combination. Curvature and snap-through load measurements have not substantially changed due to fatigue loading. These findings confirm application protocols with a broad range of parameters for which the laminates can operate without significant fatigue damage and maintain their bistable performance for an infinite lifetime.