Extreme Mechanics Letters最新文献_第4页

Peculiar multi-stability observed in Yoshimura origami structures: Evolution and regulation of snapping sequence 吉村折纸结构中观察到的特殊多重稳定性：断裂序列的演化与调控

IF 4.5 3区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Extreme Mechanics Letters

Pub Date : 2026-01-01 Epub Date: 2025-11-26 DOI: 10.1016/j.eml.2025.102427

Xiao Hu , Haiping Wu , Qiwei Zhang , Hongbin Fang

Multi-stability, a hallmark of architected materials, has rarely been associated with Yoshimura origami—a classical pattern long regarded as mono-stable. In this study, we report the first experimental observation of peculiar multi-stability in Yoshimura structures and investigate both its evolution and regulation. By systematically varying the diagonal angle of the crease pattern, we reveal that small angles (≤30°) yield smooth, mono-stable force–displacement responses, whereas slightly larger angles (>30°) induce geometric incompatibility, facet bending, and successive snapping events. In particular, pronounced multi-stability emerges in structures with larger diagonal angles (34°), where multiple stable equilibria and negative stiffness phenomena are observed. To regulate these snapping, we introduce a crease-design strategy based on the PALEO cutting pattern, and experimentally establish quantitative relationships between crease stiffness and geometric design parameters. By tailoring crease stiffness across different sections of a Yoshimura prototype, all six possible snapping sequences in a three-section structure are successfully realized under compression. These results establish Yoshimura origami as a new member of the multi-stable origami family and introduce a systematic framework for regulating its snapping behavior, offering new opportunities for adaptive structures, mechanical computing, and programmable metamaterials.

多稳定性，建筑材料的一个标志，很少与吉村折纸——一种长期被认为是单稳定的经典图案——联系在一起。在这项研究中，我们首次报道了吉村结构中特殊的多重稳定性的实验观察，并研究了它的演变和调控。通过系统地改变折痕图的对角角，我们发现小角度（≤30°）产生光滑的、单稳定的力-位移响应，而稍大的角度（>30°）会导致几何不相容、面弯曲和连续的断裂事件。特别是，在较大对角角（34°）的结构中，出现了明显的多重稳定性，在那里观察到多重稳定平衡和负刚度现象。为了调节这些断裂，我们引入了一种基于PALEO切割模式的折痕设计策略，并通过实验建立了折痕刚度与几何设计参数之间的定量关系。通过剪裁Yoshimura原型不同部分的折痕刚度，在压缩条件下成功实现了三段结构中所有六种可能的断裂序列。这些结果确立了Yoshimura折纸作为多稳定折纸家族的新成员，并引入了一个系统的框架来调节其断裂行为，为自适应结构、机械计算和可编程超材料提供了新的机会。

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引用次数: 0

Fracture in hexagonal honeycomb lattices undergoing large deformation 在大变形的六边形蜂窝晶格中断裂

IF 4.5 3区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Extreme Mechanics Letters

Pub Date : 2026-01-01 Epub Date: 2025-11-23 DOI: 10.1016/j.eml.2025.102425

Ram Hemanth Yeerella , Shengqiang Cai

Architected materials are increasingly used in applications where large deformations are unavoidable. In the small-deformation regime, such periodic designs can be modeled as continuum elastic solids with effective elastic material properties, allowing Linear Elastic Fracture Mechanics (LEFM) to describe and predict their fracture behavior. But when such structures are pushed into large-strain conditions, often the critical design scenario—can we achieve a similar simplification to model them as continuum soft solids? In the current study, using finite element simulations of hexagonal honeycombs, we find that the crack tip stress and deformation fields are uniquely determined by the energy release rate (G), in Mode I loading. At high stretches, the stress singularity scaling relationship shifts from that predicted by LEFM to one characteristic of nonlinear hyperelastic solids. We further show that the driving force for fracture can be predicted by treating these lattices as hyperelastic continuum solids, provided the strain energy density of the uncracked lattice is known. These findings provide a pathway for a simple continuum-based framework to predict failure in a wide range of deformable architected material designs.

建筑材料越来越多地用于不可避免的大变形的应用中。在小变形状态下，这种周期性设计可以建模为具有有效弹性材料特性的连续弹性固体，允许线性弹性断裂力学（LEFM）描述和预测其断裂行为。但是，当这种结构被推到大应变条件下时，通常是关键的设计场景——我们能否实现类似的简化，将它们建模为连续软固体？在本研究中，通过对六边形蜂窝的有限元模拟，我们发现裂纹尖端的应力和变形场是唯一由能量释放率(G)决定的。在高拉伸时，应力奇点标度关系从LEFM预测的转变为非线性超弹性固体的一个特征。我们进一步表明，如果已知未裂纹晶格的应变能密度，可以通过将这些晶格视为超弹性连续固体来预测断裂的驱动力。这些发现为简单的基于连续体的框架提供了一条途径，以预测各种可变形建筑材料设计中的失效。

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引用次数: 0

Front Cover CO1 封面CO1

IF 4.5 3区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Extreme Mechanics Letters

Pub Date : 2026-01-01 Epub Date: 2026-01-06 DOI: 10.1016/S2352-4316(26)00001-5

引用次数: 0

Peeling adhesion regime transition of elastic tapes 弹性胶带的剥离附着力转变

IF 4.5 3区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Extreme Mechanics Letters

Pub Date : 2025-12-01 Epub Date: 2025-10-25 DOI: 10.1016/j.eml.2025.102414

Jianyue Deng , Changhong Linghu 令狐昌鸿 , Shubo Zhang 张舒博 , Zhiyu Ng , Deon Low , Huajian Gao , K. Jimmy Hsia , Haibao Lu

Peeling phenomena are frequently observed in nature and in various applications, including wearables, heterogeneous integration, and 2D materials fabrication. Adhesion plays a critical role in the peeling process. The standard 90-degree peeling test is widely used to measure interfacial adhesion. However, a comprehensive mechanical understanding of the transition across different adhesion regimes—energy-controlled, intermediate, and strength-dominated—remains incomplete. Although many previous theoretical models have discussed these regimes individually, a unified solution with systematic experimental validation across the entire regime spectrum is yet to be obtained. Here we systematically investigate the 90-degree peeling of elastic tapes with varying bending stiffness from rigid substrates through a combination of theoretical analysis, experiments, and finite element analysis (FEA) simulations. A general and explicit expression for the peak peeling force is formulated, capturing the full spectrum of adhesion regimes and predicting the peak force as well as the transition points accurately. The theoretical results exhibit good agreement with experimental measurements and FEA simulations across all three regimes. This study provides a unified solution to the 90-degree peeling process and a practical guideline for the design and evaluation of 90-degree peeling adhesion behavior of elastic tapes.

在自然界和各种应用中经常观察到剥落现象，包括可穿戴设备，异质集成和二维材料制造。附着力在剥离过程中起着至关重要的作用。标准的90度剥离试验被广泛用于测量界面附着力。然而，对不同粘附状态（能量控制、中间和强度主导）之间的过渡的全面的机械理解仍然不完整。尽管许多先前的理论模型已经单独讨论了这些状态，但尚未获得一个统一的解决方案，并在整个状态谱中进行了系统的实验验证。本文通过理论分析、实验和有限元分析（FEA）模拟相结合的方法，系统地研究了具有不同弯曲刚度的弹性带从刚性基板上90度剥落的情况。对于峰值剥离力的一般和明确的表达式被制定，捕捉粘接力的全谱和预测峰值力以及准确的过渡点。理论结果与实验测量和有限元模拟结果吻合良好。本研究为90度剥离过程提供了统一的解决方案，并为弹性胶带90度剥离粘附性能的设计和评价提供了实用指南。

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引用次数: 0

Rate-dependent molecular size effects govern the inverse thickness dependence of specific penetration energy in nanoscale thin films 速率依赖的分子尺寸效应决定了纳米薄膜中比穿透能的逆厚度依赖

IF 4.5 3区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Extreme Mechanics Letters

Pub Date : 2025-12-01 Epub Date: 2025-11-11 DOI: 10.1016/j.eml.2025.102419

Heather L. White , Wei Chen , Nicola M. Pugno , Sinan Keten

Laser-induced projectile impact tests (LIPIT) enable evaluation of thin film mechanical properties at strain rates on the order of 10

^{8}

s⁻¹. A popular metric for comparing material performance in LIPIT is the specific penetration energy (

E_{p}^{*}

) which is meant to represent the microprojectile’s energy loss normalized by the impacted film plug. However, recent LIPIT and LIPIT-like simulations have revealed in polymer-based films an inverse dependence of

E_{p}^{*}

on nanoscale film thickness, indicating the presence of dissipative mechanisms unique to this scale. Here we report this same inverse thickness dependence in multilayered graphene oxide (GO) thin films subjected to LIPIT-like molecular dynamics simulations. A previously proposed analytical model is adjusted to suit layered materials such as GO. The influence of this model’s parameters is probed with the aid of a Gaussian process metamodel, revealing that the aforementioned scaling is most dramatic when graphene oxide flakes are large and impact velocity is low. This work builds upon many theories pertaining to the mechanisms contributing to inverse dependence of

E_{p}^{*}

on film thickness and will inform subsequent work on molecular design of ballistic impact-resistant thin films.

激光诱导弹射冲击试验（LIPIT）能够在108 s−1量级的应变速率下评估薄膜的力学性能。在LIPIT中比较材料性能的一个常用度量是比穿透能（Ep *），它表示微弹的能量损失经冲击膜塞归一化。然而，最近的LIPIT和类LIPIT模拟已经揭示了聚合物基薄膜中Ep *与纳米级薄膜厚度的反比依赖性，表明存在这种尺度特有的耗散机制。在这里，我们在多层氧化石墨烯（GO）薄膜中进行了类似lipt的分子动力学模拟，报告了相同的逆厚度依赖性。先前提出的分析模型进行了调整，以适应层状材料，如氧化石墨烯。借助高斯过程元模型探讨了模型参数的影响，发现当氧化石墨烯薄片较大且冲击速度较低时，上述结垢现象最为明显。这项工作建立在许多理论的基础上，这些理论与Ep *对薄膜厚度的反向依赖机制有关，并将为后续抗弹道冲击薄膜的分子设计工作提供信息。

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引用次数: 0

Self-locking and stability of the bowline knot 自锁和稳定的蝴蝶结结

IF 4.5 3区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Extreme Mechanics Letters

Pub Date : 2025-12-01 Epub Date: 2025-10-27 DOI: 10.1016/j.eml.2025.102413

Bastien F.G. Aymon , Fani Derveni , Michael Gomez , Jérôme Crassous , Pedro M. Reis

We investigate the self-locking of the bowline knot through numerical simulations, experiments, and theoretical analysis. Specifically, we perform two complementary types of simulations using the 3D finite-element method (FEM) and a reduced-order model based on the discrete-element method (DEM). For the FEM simulations, we develop a novel mapping technique that automatically transforms the centerline of the rod into the required knot topology prior to loading. In parallel, we conduct experiments using a nearly inextensible elastic rod tied into a bowline around a rigid cylinder. One end of the rod is pulled to load the knot while the other is left free. The measured force–displacement response serves to validate both the FEM and DEM simulations. Leveraging these validated computational frameworks, we analyze the internal tension profile along the rod’s centerline, revealing that a sharp drop in tension concentrates around a strategic locking region, whose geometry resembles that observed in other knot types. By considering the coupling of tension, bending, and friction, we formulate a theoretical model inspired by the classic capstan problem to predict the stability conditions of the bowline, finding good agreement with our FEM and DEM simulations. Our methodology and findings offer new tools and insights for future studies on the performance and reliability of other complex knots.

本文通过数值模拟、实验和理论分析研究了弓形结的自锁特性。具体来说，我们使用三维有限元法（FEM）和基于离散元法（DEM）的降阶模型进行了两种互补类型的模拟。对于有限元模拟，我们开发了一种新的映射技术，可以在加载之前自动将杆的中心线转换为所需的结拓扑结构。与此同时，我们用一根几乎不可伸缩的弹性杆系在一个刚性圆柱体上的弓形线上进行实验。拉杆的一端用来装绳结，而另一端是空着的。测量的力-位移响应用于验证FEM和DEM模拟。利用这些经过验证的计算框架，我们分析了沿杆中心线的内部张力分布，发现张力急剧下降集中在一个战略锁定区域周围，其几何形状与其他类型的结相似。在考虑张力、弯曲和摩擦耦合的情况下，我们建立了一个受经典绞盘问题启发的理论模型来预测弓形索的稳定条件，结果与FEM和DEM模拟结果吻合较好。我们的方法和发现为未来研究其他复杂节的性能和可靠性提供了新的工具和见解。

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引用次数: 0

Complex plastic deformation in glassy thin polymer films on 3D-printed auxetic lattices 3d打印的形变晶格上的玻璃状聚合物薄膜的复杂塑性变形

IF 4.5 3区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Extreme Mechanics Letters

Pub Date : 2025-12-01 Epub Date: 2025-11-18 DOI: 10.1016/j.eml.2025.102422

Kenya Hazell , Anesia Auguste , Andrew Gillman , Lawrence F. Drummy

Traditionally, plastic deformation and the micromechanics of thin polymer films have been evaluated under uniaxial or linear strain. As the use of thin film polymeric materials continues to expand into applications in flexible electronics, gas separation, energy storage and sensing, more work needs to be done to understand how these materials behave under realistic conditions. Concurrently, certain mechanical metamaterials offer the ability to investigate non-linear and multi-axis micromechanics through lattice structures with designed spatially-varying complex strain fields. While previous studies using a support structure have been performed to study polymer crazing in thin films under biaxial or shear conditions, their behavior under complex strain has not been reported. This work offers a new method in which complex strain analysis in polymer films can be performed using an auxetic support lattice with a designed Poisson’s ratio (v) that is defined by the geometry of the lattice, not the Poisson’s ratio of the material. A comparative study was performed between thin films supported on lattices with Poisson’s ratio (v = +0.2 and −0.8) lattice to represent a pseudo-uniaxial and complex strain case, respectively. The uniaxial strain lattice demonstrated similar craze propagation, area fraction, and craze interaction behavior to what has been previously observed using traditional methods, e.g. a copper grid support lattice. For the complex strain analysis, the craze appearances observed in the middle section of the bowtie reflected what was expected for the uniaxial case while the end region showed a biaxial strain field. A potential for shearing was noted in the end of the bowties for the parallel strain direction with crazes growing at 45°. Due to the difference in strain distribution within the complex lattice, a delayed onset was observed in the bowtie end region parallel to strain direction. The initial results of complex crazing using an auxetic lattice was successful in demonstrating how crazes behave under a strain field on an auxetic lattice support with v = -0.8.

传统上，聚合物薄膜的塑性变形和微观力学是在单轴或线性应变下进行评估的。随着薄膜聚合物材料在柔性电子、气体分离、能量存储和传感领域的应用不断扩大，需要做更多的工作来了解这些材料在现实条件下的表现。同时，某些机械超材料通过设计具有空间变化复杂应变场的晶格结构提供了研究非线性和多轴微观力学的能力。虽然以前的研究使用支撑结构来研究聚合物在双轴或剪切条件下在薄膜上的裂纹，但它们在复杂应变下的行为尚未报道。这项工作提供了一种新的方法，在这种方法中，聚合物薄膜中的复杂应变分析可以使用具有设计泊松比(v)的辅助支撑晶格进行，该支撑晶格由晶格的几何形状定义，而不是由材料的泊松比定义。采用泊松比（v = +0.2）和泊松比（v = - 0.8）晶格支撑薄膜，分别对拟单轴应变和复杂应变情况进行了对比研究。单轴应变晶格表现出类似的裂纹扩展、面积分数和裂纹相互作用行为，与之前使用传统方法观察到的类似，例如铜网格支撑晶格。在复杂应变分析中，在领结中部观察到的开裂现象反映了单轴情况，而末端区域则显示了双轴应变场。当裂纹在45°方向上生长时，在平行应变方向的结结末端有可能发生剪切。由于复合晶格内应变分布的差异，在平行于应变方向的领结端区观察到延迟发生。在v = -0.8的条件下，利用辅助晶格进行复合裂纹的初步结果成功地展示了裂纹在应变场下的行为。

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引用次数: 0

Front cover CO1 前盖CO1

IF 4.5 3区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Extreme Mechanics Letters

Pub Date : 2025-12-01 Epub Date: 2025-12-08 DOI: 10.1016/S2352-4316(25)00144-0

引用次数: 0

The nonlinear elastic response of magnetorheological elastomers 磁流变弹性体的非线性弹性响应

IF 4.5 3区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Extreme Mechanics Letters

Pub Date : 2025-12-01 Epub Date: 2025-10-14 DOI: 10.1016/j.eml.2025.102412

Chao Wang , Yingqi Jia , Arvin Ardebili Sharma , Zhi Zhao , Xiaojia Shelly Zhang

Magnetorheological elastomers (MREs), consisting of a soft elastomeric matrix embedded with rigid (and typically magnetized) particles such as NdFeB, are increasingly used in mechanical and biomedical applications. Accurate modeling of their magneto-mechanical behavior requires first predicting their purely mechanical response. Traditionally, this mechanical prediction has relied on directly measuring the macroscopic response of MREs, either numerically or experimentally, for each particle fraction of interest, a procedure that is both time-consuming and labor-intensive. In this study, we replace that procedure with a simple computational framework that requires only a single measurement on the unfilled elastomer. The framework treats MREs as general incompressible filled elastomers and predicts their nonlinear elastic response by integrating several established modeling techniques. For any physically admissible particle volume fraction, it analytically predicts the macroscopic nonlinear response from the measured properties of the unfilled elastomer. We validate the framework experimentally across a wide range of cross-link densities in the elastomeric matrices, particle volume fractions (0%–28%), and specimen geometries, subjected to both uniform and highly localized large deformations (with local strains up to

\sim

600%). The experimental results show excellent agreement with the computational predictions, confirming the framework as a fast and reliable tool for predicting the nonlinear elastic response of MREs. Consequently, this study offers a practical tool for streamlining the modeling and design of MRE-based structures.

磁流变弹性体（MREs）由嵌入刚性（通常磁化）颗粒（如钕铁硼）的软弹性体基体组成，越来越多地用于机械和生物医学应用。要对其磁力学行为进行精确建模，首先需要预测其纯力学响应。传统上，这种力学预测依赖于直接测量MREs的宏观响应，无论是数值还是实验，对于每个感兴趣的粒子分数，这一过程既耗时又费力。在这项研究中，我们用一个简单的计算框架取代了这一过程，该框架只需要对未填充的弹性体进行一次测量。该框架将MREs视为一般的不可压缩填充弹性体，并通过集成几种已建立的建模技术来预测其非线性弹性响应。对于任何物理上允许的颗粒体积分数，它解析地预测了未填充弹性体的宏观非线性响应。我们在弹性体基质、颗粒体积分数（0%-28%）和试样几何形状的广泛交联密度范围内对框架进行了实验验证，这些结构受到均匀和高度局部化的大变形（局部应变高达~ 600%）的影响。实验结果与计算预测结果吻合良好，证实了该框架是一种快速、可靠的预测mre非线性弹性响应的工具。因此，本研究为简化基于mre的结构的建模和设计提供了实用的工具。

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引用次数: 0

Tensegrity metastructure with tunable stiffness, strength, and energy dissipation 具有可调刚度、强度和能量耗散的张拉整体元结构

IF 4.5 3区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Extreme Mechanics Letters

Pub Date : 2025-12-01 Epub Date: 2025-11-13 DOI: 10.1016/j.eml.2025.102420

Filipe A. Santos

This paper introduces a tensegrity metastructure—a geometry-governed, structural-scale assembly—composed of three-dimensional Class-3 D-bar units. A proof-of-concept module was fabricated by fused-filament 3D printing with PETG struts and TPU ties and tested under cyclic axial loading. The metastructure exhibits a nonlinear force–displacement response with a two-stage mechanism: an initial softening regime governed by energy dissipation, followed by a sharp stiffening triggered by a locking transition as the struts align with the loading axis. Finite-element simulations, calibrated with manufacturer material data and validated against experiments, accurately reproduce this behavior.

A numerical parametric study demonstrates that the metastructure’s response can be tuned purely through geometry. Increasing the unit-cell orientation angle

β

leads to more than threefold gains in both stiffness and load capacity, and roughly a threefold increase in dissipated energy before locking. These results confirm the feasibility of geometry-based programmability, positioning tensegrity metastructures as lightweight, modular systems for adaptive mechanical performance in vibration mitigation, impact absorption, deployable architectures, and soft robotic mechanisms.

本文介绍了一种张拉整体元结构——由三维三维d -杆单元组成的几何控制的结构尺度组合。采用熔融长丝3D打印技术，采用PETG支柱和TPU纽带制作了一个概念验证模块，并在循环轴向载荷下进行了测试。元结构表现出非线性力-位移响应，具有两阶段机制：由能量耗散控制的初始软化状态，随后是由支撑与加载轴对齐时的锁定过渡触发的急剧硬化。使用制造商材料数据校准并通过实验验证的有限元模拟可以准确地再现这种行为。数值参数研究表明，元结构的响应可以完全通过几何来调整。增加单元格取向角β导致刚度和负载能力增加三倍以上，锁定前的耗散能量增加大约三倍。这些结果证实了基于几何的可编程性的可行性，将张拉整体元结构定位为轻量化、模块化系统，用于自适应机械性能的振动缓解、冲击吸收、可展开架构和软机器人机构。

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引用次数: 0