arXiv subjects

Haiyi Liang

Publications and source records attributed to Haiyi Liang.

7 recordsLinked to original sources

arXiv2026

Helical stability of double-stranded semiflexible chains with interstrand interactions

The mechanical and structural properties of dsDNA have been successfully described by models with varying levels of complexity and coarse-graining schemes. Prior work has characterized local stacking/twist effects and force-torque phase diagrams under external constraints. However, the role of base-pairing and torsional elasticity in global morphological transitions remain poorly characterized in the absence of external constraints. Here we investigate the delicate balance required for the strength of base-pairing interactions and the twisting energy to preserve the double-helix structure in a model made up of two semiflexible chains. We found that the model exhibits several distinct morphological phases: flat, random coil, double-helix, and the unwound double-helix. We calculate the Gauss linking number to characterize transitions between these phases.

cond-mat.soft↗

arXiv2026

Emergence of Hexanematic Order in a Growing Confluent Cell Monolayer

Collective migration of epithelial layers underlies processes ranging from wound healing to cancer invasion. A defining yet challenging feature is the emergence of distinct cell morphologies within a single migrating confluent sheet, with larger, elongated cells at the active boundary and smaller, hexatically ordered cells in the bulk. Here, we develop a stochastic particle-Voronoi framework that captures this hexanematic organization without prescribing target geometries and distinct cell types. We show that boundary-driven collective motion generates an outward velocity gradient. This gradient, coupled to a density and velocity-dependent division rule, produces peripheral cells that are larger, more elongated, and more defect-prone, while bulk cells remain smaller, isotropic, and hexagonally packed. These results show how minimal, non-equilibrium mechanical interactions give rise to emergent, self-organized tissue-scale patterning during collective migration.

cond-mat.soft↗

arXiv2025

Inverse Discrete Elastic Rod

Inverse design of slender elastic structures underlies a wide range of applications in computer graphics, flexible electronics, biomedical devices, and soft robotics. Traditional optimization-based approaches, however, are often orders of magnitude slower than forward dynamic simulations and typically impose restrictive boundary conditions. In this work, we present an inverse discrete elastic rods (inverse-DER) method that enables efficient and accurate inverse design under general loading and boundary conditions. By reformulating the inverse problem as a static equilibrium in the reference configuration, our method attains computational efficiency comparable to forward simulations while preserving high fidelity. This framework allows rapid determination of undeformed geometries for elastic fabrication structures that naturally deform into desired target shapes upon actuation or loading. We validate the approach through both physical prototypes and forward simulations, demonstrating its accuracy, robustness, and potential for real-world design applications.

cs.GR↗

arXiv2020

Constructing rigid-foldable generalized Miura-ori tessellations for curved surfaces

Origami has shown the potential to approximate three-dimensional curved surfaces by folding through designed crease patterns on flat materials. The Miura-ori tessellation is a widely used pattern in engineering and tiles the plane when partially folded. Based on constrained optimization, this paper presents the construction of generalized Miura-ori patterns that can approximate three-dimensional parametric surfaces of varying curvatures while preserving the inherent properties of the standard Miura-ori, including developability, flat-foldability and rigid-foldability. An initial configuration is constructed by tiling the target surface with triangulated Miura-like unit cells and used as the initial guess for the optimization. For approximation of a single target surface, a portion of the vertexes on the one side is attached to the target surface; for fitting of two target surfaces, a portion of vertexes on the other side is also attached to the second target surface. The parametric coordinates are adopted as the unknown variables for the vertexes on the target surfaces whilst the Cartesian coordinates are the unknowns for the other vertexes. The constructed generalized Miura-ori tessellations can be rigidly folded from the flat state to the target state with a single degree of freedom.

cs.CE↗

arXiv2020

Folding Simulation of Rigid Origami with Lagrange Multiplier Method

Origami crease patterns are folding paths that transform flat sheets into spatial objects. Origami patterns with a single degree of freedom (DOF) have creases that fold simultaneously. More often, several substeps are required to sequentially fold origami of multiple DOFs, and at each substep some creases fold and the rest remain fixed. In this study, we combine the loop closure constraint with Lagrange multiplier method to account for the sequential folding of rigid origami of multiple DOFs, by controlling the rotation of different sets of creases during successive substeps. This strategy is also applicable to model origami-inspired devices, where creases may be equipped with rotational springs and the folding process involves elastic energy. Several examples are presented to verify the proposed algorithms in tracing the sequential folding process as well as searching the equilibrium configurations of origami with rotational springs.

cs.CE↗

arXiv2019

Topology, geometry and mechanics of surgical Z-plasty

Reconstructive surgeries often use topological manipulation of tissue to minimize post-operative scarring. The most common version of this, Z-plasty, involves modifying a straight line cut into a Z-shape, followed by a rotational transposition of the resulting triangular pedicle flaps, and a final restitching the wound. This locally reorients the anisotropic stress field and reduces the potential for scarring. We analyze the planar geometry and mechanics of the Z-plasty to quantify the rotation of the overall stress field and the local forces on the restitched cut using theory, simulations and simple physical Z-plasty experiments with foam sheets that corroborate each other. Our study rationalizes the most typical surgical choice of this angle, and opens the way for a range of surgical decisions by characterizing the stresses along the cut.

cond-mat.soft↗

arXiv2012

Geometric Mechanics of Periodic Pleated Origami

Origami is the archetype of a structural material with unusual mechanical properties that arise almost exclusively from the geometry of its constituent folds and forms the basis for mechanical metamaterials with an extreme deformation response. Here we consider a simple periodically folded structure Miura-ori, which is composed of identical unit cells of mountain and valley folds with four-coordinated ridges, defined completely by 2 angles and 2 lengths. We use the geometrical properties of a Miura-ori plate to characterize its elastic response to planar and non-planar piece- wise isometric deformations and calculate the two-dimensional stretching and bending response of a Miura-ori sheet, and show that the in-plane and out-of-plane Poisson's ratios are equal in magnitude, but opposite in sign. Our geometric approach also allows us to solve the inverse design problem of determining the geometric parameters that achieve the optimal geometric and mechanical response of such structures.

physics.class-ph↗