提出统一离散微分几何框架,精准模拟细长带状物的宽厚依赖力学行为。
Discrete Elastic Ribbons: A Unified Discrete Differential Geometry Framework for One-Dimensional Energy Models

- 基于离散微分几何构建耦合弯扭能模型,取代传统线性叠加方式。
- Sano模型预测的失稳阈值最接近有限元仿真,准确捕捉宽度影响。
- 高性能JAX实现支持隐式积分,计算开销仅略高于标准弹性棒模型。
弹性带状物是长度(L)、宽度(W)和厚度(b)满足 L ≫ W ≫ b 的细长结构,其力学行为介于一维杆与二维板之间。在基于基尔霍夫型杆的二次能量框架(如离散弹性棒,DER)中,平衡方程与宽度无关,无法刻画宽度依赖效应。中心线简化模型虽尝试通过耦合弯扭能引入宽度依赖,但缺乏统一仿真框架,其精度不明确。本文提出一种基于离散微分几何的统一框架,将能量表达为沿中线耦合弯扭应变度量的函数,而非DER中的二次弯扭能线性和。推导出能量的解析梯度与海森矩阵,支持隐式时间积分。在此统一设置下,对比了五种带状模型:基尔霍夫、Sadowsky、Wunderlich、Sano与Audoly。以纵向约束成预屈曲拱的直带受横向位移,诱发超临界叉式分岔为基准,比较各模型预测的分岔阈值与壳体有限元仿真结果。Sano模型在捕捉宽度依赖偏移方面表现最优。高效率的JAX实现达到每迭代$/mathcal{O}(N)$复杂度,且相较于标准DER,Sano模型额外开销可忽略。
原文摘要 · Abstract (English)
Elastic ribbons, slender structures whose length ($L$), width ($W$), and thickness ($b$) satisfy $L \gg W \gg b$, exhibit mechanical behaviors intermediate between one-dimensional rods ($L \gg W, b$) and two-dimensional plates ($L, W \gg b$). In quadratic Kirchhoff-type rod-based frameworks, such as Discrete Elastic Rods (DER), the governing equilibrium equations are independent of width, and therefore these models cannot capture width-dependent mechanical effects. Reduced centerline-based ribbon models attempt to capture width dependence via coupled bending-twisting energies. However, their relative accuracy remain unclear due to the absence of a unified simulation framework. In this work, we formulate a framework grounded in discrete differential geometry where the energy is expressed as functions of coupled bending-twisting strain measures along the centerline, rather than a linear sum of quadratic bending and twisting energies in DER. We derive analytical gradients and Hessians of the energy that enable implicit time integration. Within this unified setting, we compare five ribbon models: Kirchhoff, Sadowsky, Wunderlich, Sano, and Audoly. As a benchmark, a straight ribbon is longitudinally constrained into a pre-buckled arch and subjected to transverse displacement, inducing a supercritical pitchfork bifurcation. Predicted bifurcation thresholds are compared against shell-based finite element simulations, with the Sano model providing the closest agreement in capturing width-dependent shifts. Our high-performance JAX-based implementation achieves $\mathcal{O}(N)$ per-iteration cost and also confirms that Sano model introduces negligible per-iteration overhead relative to standard DER.
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