arXiv subjects

Jinkyu Yang

Publications and source records attributed to Jinkyu Yang.

At least 19 recordsLinked to original sources

arXiv2026

Kirigami Meta-Sheet for Enhanced Impact Absorption

Impact absorbers based on mechanical metamaterials often use bulky, vertically stacked architectures, limiting large area deployment and scalable manufacturing. Here, we propose a kirigami meta-sheet as a planar absorber that uses transitions between positive and negative stiffness regimes rather than sacrificial crushing. Guided by an analysis of a simple mass-spring-damper model, we program the stiffness of kirigami meta-sheets through the hinge ratio connecting the unit cells. Quasistatic indentation experiments confirm that the meta-sheet with a low hinge ratio most clearly exhibits the negative stiffness transition. The drop-tower tests show that it reduces rebound, decreases the first impact force, and increases dissipation. Unlike polyethylene mesh and styrofoam, this kirigami meta-sheet is shown to be effective in protecting a falling egg. Its planar geometry enables area scaling by tiling and is compatible with sheet level manufacturing routes such as cutting, molding, and lamination, establishing kirigami meta-sheets as practical impact absorbers.

cs.CE↗

arXiv2026

Supratransmission in Lattices with Purely Nonlinear Coupling

Supratransmission is examined in nonlinear lattices with purely nonlinear coupling, extending the phenomenon to systems that lack a linear pass band. In contrast to standard lattices with mixed linear-nonlinear interactions, the present model has no linear spectrum, so energy propagation arises entirely from nonlinear effects. Asymptotic analysis yields a discrete $p$-Schr\"odinger (DpS) equation that {provides an accurate description in the weak- and intermediate-coupling regimes and offers qualitative insight in the strong-coupling regime}. Perturbation provides analytical approximations for the critical driving amplitude, explicitly showing its dependence on the driving frequency, coupling strength, and the nonlinearity exponent $p$. The analysis identifies a non-trivial dependence of the critical amplitude on $p$, with distinct trends in different coupling regimes. Numerical continuation and direct simulations {validate the theory in regimes where the asymptotic reduction is applicable and show good agreement across a wide range of parameters}. The results establish supratransmission in fully nonlinear lattices and clarify the associated energy-transport mechanisms, with relevance to mechanical lattices, tunable metamaterials, and nonlinear optical arrays.

nlin.PS↗

arXiv2026

Formation of mechanical rogue waves

Rogue waves, characterized by their abrupt and extreme localization in space and time, have evolved from maritime folklore to subjects of intense study across diverse fields, from hydrodynamics and nonlinear optics to plasmas and condensed matter physics. In mechanical systems, however, experimental realization remains elusive despite theoretical and numerical predictions. This gap stems from the stringent requirements for controllable nonlinearity, the high-fidelity initialization of the system, and the necessity to overcome inherent energy dissipation. Here, we report the experimental formation of mechanical rogue waves in a precisely engineered one-dimensional metamaterial lattice with tailored nonlinearity and minimal dissipative losses. Using a precision electromagnetic release system, we prescribe initial strain profiles that trigger a transition from dispersive decay to extreme wave focusing. Our parametric analysis reveals that the emergence of these extreme events is strictly contingent upon a synergy between high nonlinearity and a broad spatial energy reservoir within the initial seed. Crucially, neither factor alone is sufficient to overcome dispersion and trigger the observed focusing. These findings establish a robust platform for studying transient nonlinear wave focusing phenomena in mechanical systems and offer insights for harnessing extreme wave localization for applications such as energy harvesting, waveguiding, and mechanical signal processing.

nlin.PS↗

arXiv2026

Size-Dependent Properties of Miura-ori Tessellations

We investigate the size-dependent behavior of Miura-ori-based origami tessellations by changing the number of origami unit cells. For large tessellations, the Miura-ori sheet generally exhibits a negative in-plane Poisson's ratio, whereas if the size of the Miura-ori tessellations becomes small, the transition between positive and negative Poisson's ratio emerges in the middle of the folding process. Here, we show that such a transitioning point, i.e., zero Poisson's ratio, yields a kinematic locking state. We also experimentally demonstrate the tunable locking behavior altered by tessellation sizes. Extending the analysis to three-dimensional origami tessellations, we find that the direction of kinematic locking changes depending on the tessellation size. Varying tessellation size thus enables control over both the onset and the direction of locking in origami metamaterials.

physics.app-ph↗

arXiv2026

A Unified Framework for Kinematic Simulation of Rigid Foldable Structures

Origami-inspired structures with rigid panels now span thick, kirigami, and multi-sheet realizations, making unified kinematic analysis essential. Yet a general method that consolidates their loop constraints has been lacking. We present an automated approach that generates the Pfaffian constraint matrix for arbitrary rigid foldable structures (RFS). From a minimally extended data schema, the tool constructs the facet-hinge graph, extracts a minimum cycle basis that captures all constraints, and assembles a velocity-level constraint matrix via screw theory that encodes coupled rotation and translation loop closure. The framework computes and visualizes deploy and fold motions across diverse RFS while eliminating tedious and error-prone constraint calculations.

cs.RO↗

arXiv2025

Inverse design of flat-foldable volumetric origami with smooth curved profile

Through flat-folding, origami provides an extremely compact packaging strategy for deployable structures in aerospace, architecture, and robotics. However, origami's flat, volumeless facets limit the formation of smooth curvature, restricting its applicability in systems where smooth curved geometries are essential for performance, such as aerospace and electromagnetic communication systems. Here, we propose volumetric origami that preserves smooth curvature and an inverse design method that generates flat-foldable volumetric origami for given target curved surfaces. The flat-foldability enables arbitrarily prescribed compactness in volumetric origami folding, with its stowage efficiency governed by the number of cells and the target profile. The structural integrity and engineering feasibility of volumetric origami are validated through successful flight testing of a UAV equipped with flat-foldable volumetric origami wings replicating a target airfoil. Our approach bridges the gap between planar origami and the curvature requirements of engineering systems, expanding design freedom for curved structures under stringent spatial constraints.

cond-mat.soft↗

arXiv2025

Physics-Informed Neural Networks for Programmable Origami Metamaterials with Controlled Deployment

Origami-inspired structures provide unprecedented opportunities for creating lightweight, deployable systems with programmable mechanical responses. However, their design remains challenging due to complex nonlinear mechanics, multistability, and the need for precise control of deployment forces. Here, we present a physics-informed neural network (PINN) framework for both forward prediction and inverse design of conical Kresling origami (CKO) without requiring pre-collected training data. By embedding mechanical equilibrium equations directly into the learning process, the model predicts complete energy landscapes with high accuracy while minimizing non-physical artifacts. The inverse design routine specifies both target stable-state heights and separating energy barriers, enabling freeform programming of the entire energy curve. This capability is extended to hierarchical CKO assemblies, where sequential layer-by-layer deployment is achieved through programmed barrier magnitudes. Finite element simulations and experiments on physical prototypes validate the designed deployment sequences and barrier ratios, confirming the robustness of the approach. This work establishes a versatile, data-free route for programming complex mechanical energy landscapes in origami-inspired metamaterials, offering broad potential for deployable aerospace systems, morphing structures, and soft robotic actuators.

cond-mat.soft↗

arXiv2025

Topological edge states and amplitude-dependent delocalization in quasiperiodic elliptically geared lattices

We present a class of mechanical lattices based on elliptical gears with quasiperiodic modulation and geometric nonlinearity, capable of exhibiting topologically protected modes and amplitude-driven transitions. Starting from a one-dimensional chain of modulated elliptical gears, we demonstrate the emergence of localized edge states arising from quasiperiodic variation in the gears' moments of inertia, analogous to the topological edge modes of the Aubry-Andre-Harper model. Under increasing excitation amplitude, the system undergoes a nonlinear transition, where edge localization breaks down and energy delocalizes into the bulk. By coupling multiple such chains with varying modulation phase, we construct a two-dimensional lattice in which the phase acts as a synthetic dimension. This structure supports topological wave propagation along the synthetic dimension. Nonlinearity again induces a breakdown of topological states, leading to complex, amplitude-dependent wave propagation. We further propose a numerical continuation approach to analyzing the periodic orbits and their linear stability, effectively discovering the boundary of the basin of bounded motion and detecting the occurrence of delocalization under certain excitation amplitudes. Our results reveal that elliptical geared systems offer a passive, amplitude-dependent platform for exploring topological phenomena and synthetic dimensionality in mechanical metamaterials.

physics.app-ph↗

arXiv2025

Passive Vibration Isolation Characteristics of Negative Extensibility Metamaterials

Negative extensibility refers to the category of mechanical metamaterials having an unusual phenomenon where the system contracts upon expansion. The dynamic analysis of such systems is crucial for exploring the vibration isolation characteristics, forming the prime focus of the present study. Inspired by the Braess paradox, the mechanical model incorporates coupled tunable nonlinear spring stiffness properties (strain hardening and softening), which alternate when a certain displacement threshold is exceeded. This stiffness switching mechanism facilitates low frequency passive vibration isolation using the phenomenon of countersnapping instability. The vibration isolation characteristics resulting from the stiffness switching mechanism are investigated using time and frequency domain plots. Furthermore, the relationship between the stiffness switching mechanism and various system parameters is visualized using a three dimensional parametric space. The efficacy of the proposed system is evaluated by comparing it with the existing bistable systems, revealing superior performance in isolating high-amplitude vibrations. The proposed mechanism enhances the understanding of dynamic behaviors in critical structural elements for multistable mechanical metamaterials, providing insights and opportunities for innovative adaptive designs.

nlin.AO↗

arXiv2025

Unveiling Solitonic Collisions in Mechanical Metamaterials

Interactions between solitary waves have been pivotal to understanding nonlinear phenomena across various disciplines. The dynamics of rarefaction solitary waves holds great potential, yet their fundamental characteristics and interactions remain only partially understood through experimental means in mechanical metamaterials. Previous studies highlighted their existence and proposed applications, such as waveguides, impact mitigation, and energy harvesting. Challenges, including energy dissipation and a lack of precise measurement techniques, have hindered deeper exploration, most notably of solitonic collisions. In this work, we provide a definitive platform for examining pure rarefaction solitons propagating through a strain-softening mechanical lattice, addressing these challenges. Employing a theoretical framework based on the Boussinesq approximation and multiple-scale analysis, we predict soliton behavior, including phase shifts resulting from head-on collisions. These theoretical insights are corroborated through numerical simulations and systematic experiments designed to generate and measure pure rarefaction solitons with high precision. Both symmetric and asymmetric collisions are examined, revealing practically elastic interaction behaviors and amplitude-dependent phase shifts. Furthermore, collision dynamics, such as speed and phase shifts during rarefaction soliton collisions, from the experimental results show agreement with theoretical and numerical models. These results validate our experimental platform and findings, underscoring the potential of mechanical rarefaction solitons as robust, controllable wave packets. This suggests a robust paradigm for exploring nonlinear wave interactions in mechanical systems, opening new application avenues in mechanical metamaterials, such as wave-based computing and advanced signal processing.

nlin.PS↗

arXiv2024

On-demand realization of topological states using Miura-folded metamaterials

Recent advancements in topological metamaterials have unveiled fruitful physics and numerous applications. Whereas initial efforts focus on achieving topologically protected edge states through principles of structural symmetry, the burgeoning field now aspires to customize topological states, tailoring their emergence and frequency. Here, our study presents the realization of topological phase transitions utilizing compliant mechanisms on the facets of Miura-folded metamaterials. This approach induces two opposite topological phases, leading to topological states at the interface. Moreover, we exploit the unique folding behavior of Miura-folded metamaterials to tune the frequency of topological states and dynamically toggle their presence. Our research not only paves the way for inducing topological phase transitions in Miura-folded structures but also enables the on-demand control of topological states, with promising applications in wave manipulation and vibration isolation.

physics.app-ph↗

arXiv2024

Unveiling dynamic bifurcation of Resch-patterned origami for self-adaptive impact mitigation structure

A long-standing challenge in impact mitigation is the development of versatile and omnifarious protective structures capable of encompassing a wide spectrum of scenarios, for example, ranging from low-speed pedestrian impacts to high-speed vehicle collisions. However, most existing impact mitigation strategies rely on fixed geometries or pre-tuned material properties targeting specific impact speed, lacking the ability to adapt in real time. Here, we draw inspiration from origami to design impact mitigation structures that exhibit multi-modal and self-adaptive behavior. We introduce a Resch-patterned origami structure that hosts two distinctive deformation modes: a monostable folding mode and a bistable unfolding mode featuring snap-through. Impact experiments reveal a speed-dependent dynamic bifurcation, wherein the structure autonomously switches between folding and unfolding in response to the applied impact velocity. This dynamic bifurcation, intrinsically distinct from kinematic or static origami bifurcations, enables real-time selection of deformation pathways that enhance energy dissipation across a broad range of impact conditions. We further demonstrate the scalability and practical relevance of this mechanism by fabricating tessellations in a bumper-like configuration and evaluating their performance using a pendulum-based mannequin impact test. Together, these results establish dynamic bifurcation in origami-based structures as an adaptive impact mitigation strategy. This approach enables scalable and programmable protective systems that autonomously select deformation modes in real time, with broad relevance to adaptive robotics, smart protective armor, and aerospace damping technologies.

cond-mat.mtrl-sci↗

arXiv2024

Topological pumping in origami metamaterials

In this study, we present a mechanism of topological pumping in origami metamaterials with spatial modulation by tuning the rotation angles. Through coupling spatially modulated origami chains along an additional synthetic dimension, the pumping of waves from one topological edge state to another is achieved, where the Landau-Zener transition is demonstrated by varying the number of coupled origami chains. Besides, the inherent nonlinearity of origami metamaterials enable the excitation-dependent Landau-Zener tunneling probability. Furthermore, with the increase of nonlinearity, the topological states tend to localize in several regions in a way reminiscent of discrete breathers. Our findings pave the way towards inter-band transitions and associated topological pumping features in origami metamaterials.

physics.app-ph↗

arXiv2023

Physics-informed discrete element modeling for the bandgap engineering of cylinder chains

We propose an efficient method to build a simple discrete element model (DEM) that accurately simulates the oscillation of a continuum beam. The DEM is based on the Timoshenko beam theory of slender cylindrical members and their corresponding wave dynamics in assembly. This physics-informed DEM accounts for multiple vibration modes of the constituting beam elements in wide frequency ranges. We construct various DEMs mimicking cylinder chains and compare their wave dynamics with those measured in experiments to validate the proposed method. Furthermore, we construct a graded woodpile chain of slender cylinders. We experimentally and numerically investigate the frequency bandgaps of the system and demonstrate the possibility of constructing a wide bandgap by consecutively superposing multiple stop bands generated from cylinders of various lengths. This system is highly efficient in blocking propagating waves by leveraging the vibration isolation effect stemming from the local resonance of the cylinders. The proposed DEM method can be useful for investigating and designing complex vibration systems in an efficient and accurate manner. Moreover, the design approach of manipulating the frequency bandgap can be exploited for developing vibration filters and impact mitigation devices.

cond-mat.other↗

arXiv2023

Nonlinear Topological Mechanics in Elliptically Geared Isostatic Metamaterials

Despite the extensive studies of topological systems, the experimental characterizations of strongly nonlinear topological phases have been lagging. To address this shortcoming, we design and build elliptically geared isostatic metamaterials. Their nonlinear topological transitions can be realized by collective soliton motions, which stem from the transition of nonlinear Berry phase. Endowed by the intrinsic nonlinear topological mechanics, surface polar elasticity and dislocation-bound zero modes can be created or annihilated as the topological polarization reverses orientation. Our approach integrates topological physics with strongly nonlinear mechanics and promises multi-phase structures at the micro and macro scales.

cond-mat.mtrl-sci↗

arXiv2023

Elastic chiral Landau level and snake states in origami metamaterials

In this study, we present a method for generating a synthetic gauge field in origami metamaterials with continuously varying geometrical parameters. By modulating the mass term in the Dirac equation linearly, we create a synthetic gauge field in the vertical direction, which allows for the quantization of Landau levels through the generated pseudomagnetic field. Furthermore, we demonstrate the existence and robustness of the chiral zeroth Landau level. The unique elastic snake state is realized using the coupling between the zeroth and the first Landau levels. Our results, supported by theory and simulations, establish a feasible framework for generating pseudomagnetic fields in origami metamaterials with potential applications in waveguides and cloaking.

cond-mat.soft↗

arXiv2023

Geometry-informed dynamic mode decomposition in origami dynamics

Origami structures often serve as the building block of mechanical systems due to their rich static and dynamic behaviors. Experimental observation and theoretical modeling of origami dynamics have been reported extensively, whereas the data-driven modeling of origami dynamics is still challenging due to the intrinsic nonlinearity of the system. In this study, we show how the dynamic mode decomposition (DMD) method can be enhanced by integrating geometry information of the origami structure to model origami dynamics in an efficient and accurate manner. In particular, an improved version of DMD with control, that we term geometry-informed dynamic mode decomposition~(giDMD), is developed and evaluated on the origami chain and dual Kresling origami structure to reveal the efficacy and interpretability. We show that giDMD can accurately predict the dynamics of an origami chain across frequencies, where the topological boundary state can be identified by the characteristics of giDMD. Moreover, the periodic intrawell motion can be accurately predicted in the dual origami structure. The type of dynamics in the dual origami structure can also be identified. The model learned by the giDMD also reveals the influential geometrical parameters in the origami dynamics, indicating the interpretability of this method. The accurate prediction of chaotic dynamics remains a challenge for the method. Nevertheless, we expect that the proposed giDMD approach will be helpful towards the prediction and identification of dynamics in complex origami structures, while paving the way to the application to a wider variety of lightweight and deployable structures.

math.DS↗

arXiv2023

Effects of Average Number of Platelets Through the Thickness and Platelet Width on the Mechanical Properties of Discontinuous Fiber Composites

In this study, we experimentally and numerically investigate the evolution of the tensile material properties of Discontinuous Fiber Composites (DFCs) with an increasing average number of platelets through the thickness for two different platelet widths. The results show that both the number of platelets and the platelet width have significant effects on the tensile modulus and strength. We find that not only the average mechanical properties but also their coefficients of variation change according to the different DFC mesostructures. To understand the relationship between material morphology at the mesoscale and corresponding material properties, we developed a random platelet mesostructure generation algorithm combined with explicit finite element models. Leveraging the computational tools, we find that moduli and strength increase with increasing average number of platelets through the thickness. The increasing trend continues until reaching an asymptotic limit at about 45 layers through the thickness for the narrow platelets and 27 layers for the square platelets. In the study, we address the importance of having accurate simulations of the mesostructure to match not only the average modulus and strength but also their associated coefficients of variation. We show that it is possible to accurately predict the tensile material properties of DFCs, including their B-basis design values. This is a quintessential condition for the adoption of DFCs in structural applications.

cond-mat.soft↗