Extreme Mechanics Letters最新文献_第3页

Stress distribution in contractile cell monolayers 收缩细胞单层中的应力分布

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

Extreme Mechanics Letters

Pub Date : 2025-11-29 DOI: 10.1016/j.eml.2025.102426

Yucheng Huo , Kexin Guo , Massimo Paradiso , K. Jimmy Hsia

Collective behaviors in cellular systems are regulated not only by biochemical signaling pathways but also by intercellular mechanical forces, whose quantification in contractile monolayers remains poorly understood. Here, by integrating traction force microscopy and numerical simulations, we reconstruct the stress distribution in C2C12 myoblast monolayers to reveal the roles of local mechanical forces in determining the collective cellular structures. We find that contractile monolayers exhibit positive maximum and negative minimum principal stresses, reflecting the intrinsic anisotropy of active tension. Distinct stress patterns emerge around topological defects, coinciding with singularities in cell alignment, density, and morphology, indicating a strong coupling between mechanical forces and structural organization. Moreover, tensile stresses are preferentially transmitted along the cell elongation axis and compressive stresses transversely, demonstrating that local stress guides cell arrangement. This mechanical guidance appears to be universal among contractile systems, as observed also in bone marrow–derived mesenchymal stem cells. Together, our work establishes a quantitative framework for characterizing mechanical anisotropy in active cellular monolayers and reveals a general principle of force–structure coupling, providing a physical basis for understanding how mechanics governs myogenesis, morphogenesis, and collective organization in contractile cellular systems.

细胞系统中的集体行为不仅受到生物化学信号通路的调节，还受到细胞间机械力的调节，而细胞间机械力在收缩单层中的量化仍然知之甚少。在这里，我们通过结合牵引力显微镜和数值模拟，重建了C2C12成肌细胞单层中的应力分布，以揭示局部机械力在决定集体细胞结构中的作用。我们发现，收缩单分子膜表现出正的最大主应力和负的最小主应力，反映了主动张力的内在各向异性。不同的应力模式出现在拓扑缺陷周围，与细胞排列、密度和形态的奇异性相一致，表明机械力和结构组织之间存在很强的耦合。此外，拉伸应力优先沿细胞延伸轴传递，压应力横向传递，表明局部应力指导细胞排列。这种机械引导似乎在收缩系统中是普遍存在的，在骨髓来源的间充质干细胞中也观察到了这一点。总之，我们的工作建立了一个定量框架来表征活性细胞单层的力学各向异性，并揭示了力-结构耦合的一般原理，为理解力学如何控制收缩细胞系统中的肌肉发生、形态发生和集体组织提供了物理基础。

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引用次数: 0

Multi-level mechanical modeling and computational design framework for weft knitted fabrics 纬编织物多层次力学建模与计算设计框架

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

Extreme Mechanics Letters

Pub Date : 2025-11-27 DOI: 10.1016/j.eml.2025.102423

Cosima du Pasquier , Sehui Jeong , Pan Liu , Susan Williams , Nour Mnejja , Allison M. Okamura , Skylar Tibbits , Tian Chen

This work presents a multi-level modeling and design framework for weft knitted fabrics, beginning with a volumetric finite element analysis capturing their mechanical behavior from fundamental principles. Incorporating yarn-level data, it accurately predicts stress–strain responses, reducing the need for extensive physical testing. A simplified strain energy approach homogenizes the results into three key variables, enabling rapid, accurate predictions in minutes. After validation against experiments, our framework can simulate new knit fabrics without additional tests. In real-world scenarios, fabrics often feature variations in yarn materials or patterns. The framework extends to heterogeneous fabrics, showing that transitions between distinct regions can be captured using simple mechanical analogies: springs in series and parallel. This allows heterogeneous textiles to be treated as idealized patchworks of homogeneous pieces, preserving predictive accuracy. The method is demonstrated by designing and producing a compression sleeve with uniform pressure, illustrating how the framework supports development of knits tailored to specific assistance levels and anatomical features. By combining volumetric finite element analysis, simplified model through homogenization, and controlled material transitions, this approach provides a scalable, high-fidelity path toward next-generation weft knitted fabric design.

这项工作提出了纬编织物的多层次建模和设计框架，从体积有限元分析开始，从基本原理捕捉它们的机械行为。结合纱线水平数据，它准确地预测应力应变响应，减少了广泛的物理测试的需要。简化的应变能方法将结果均匀化为三个关键变量，从而在几分钟内实现快速，准确的预测。经过实验验证，我们的框架可以模拟新的针织面料，而无需额外的测试。在现实世界中，织物通常以纱线材料或图案的变化为特征。该框架扩展到异质织物，表明不同区域之间的过渡可以使用简单的机械类比来捕获：串联和平行的弹簧。这使得异质纺织品被视为同质碎片的理想拼凑物，保持预测的准确性。通过设计和生产具有均匀压力的压缩套筒来演示该方法，说明框架如何支持针对特定辅助水平和解剖特征量身定制的针织衫的开发。通过结合体积有限元分析，通过均质化简化模型和控制材料过渡，该方法为下一代纬编织物设计提供了可扩展的高保真度路径。

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引用次数: 0

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 : 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 : 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

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 : 2025-11-18 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

High-precision fluidic Kirigami morphing surface for ultrasonic holographic lensing and haptic interfacing 用于超声全息透镜和触觉接口的高精度流体基里伽米变形表面

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

Extreme Mechanics Letters

Pub Date : 2025-11-17 DOI: 10.1016/j.eml.2025.102424

Ardalan Kahak , Moustafa Sayed Ahmed , Nahid Kalantaryardebily , Hrishikesh Kulkarni , Netta Gurari , Shima Shahab , Suyi Li

Morphing surfaces provide a versatile tool to advance the functionalities of high-performance aircraft, soft robots, biomedical devices, and human–machine interfaces. However, achieving precise shape transformation and mechanical property control remains challenging due to nonlinearity, design constraints, and the difficulty of coordinating multiple constituent materials across a continuous surface. To this end, this study unveils that Kirigami art can inspire novel solutions. More specifically, the geometric principles of Kirigami can be exploited to design and fabricate fluidic morphing surfaces capable of highly accurate shape morphing and output force control, all via a single pressure input. This study presents a systematic approach to designing Kirigami for tuning the local deformation and force output through extensive nonlinear modeling and experiment validation on two archetypal patterns: concentric square and circular cuts. The potentials of this approach are demonstrated via two multiphysics case studies: (1) an acoustic holography lens for ultrasonic wave steering, achieving highly accurate deformation control under a single global pressure input, and (2) a haptic device with a small volume, constant contact area, and high-resolution output force. The fluidic Kirigami concept allows for simple yet effective adaptation to different shape and stiffness requirements, paving the way for a new family of scalable and programmable morphing surfaces.

变形表面为高性能飞机、软体机器人、生物医学设备和人机界面提供了一种多功能工具。然而，由于非线性、设计限制以及在连续表面上协调多个组成材料的困难，实现精确的形状转换和机械性能控制仍然具有挑战性。为此，本研究揭示了Kirigami艺术可以激发新的解决方案。更具体地说，Kirigami的几何原理可以用于设计和制造流体变形表面，这些表面能够通过单一压力输入实现高精度的形状变形和输出力控制。本研究提出了一种系统的方法来设计Kirigami，通过广泛的非线性建模和实验验证两种原型模式：同心正方形和圆形切割，以调整局部变形和力输出。通过两个多物理场案例研究证明了这种方法的潜力：(1)用于超声波转向的声全息透镜，在单一全局压力输入下实现高精度的变形控制，以及(2)具有小体积，恒定接触面积和高分辨率输出力的触觉设备。流体Kirigami概念允许简单而有效地适应不同的形状和刚度要求，为一系列新的可扩展和可编程变形表面铺平了道路。

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引用次数: 0

Exploring conformational landscapes of two-dimensional macromolecules via well-tempered metadynamics 通过调质元动力学探索二维大分子的构象景观

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

Extreme Mechanics Letters

Pub Date : 2025-11-15 DOI: 10.1016/j.eml.2025.102421

Yanyan Zhao , Ke Zhou , Yan Chen , Yilun Liu

Exploring conformational landscape of two-dimensional (2D) macromolecules poses a profound challenge due to their intrinsically complex free energy surfaces. Conventional computational approaches based on equilibrium molecular dynamics (MD) suffer from limited ergodic exploration, failing to adequately explore energy landscapes and transition pathways between metastable conformations. In this study, we employ well-tempered Metadynamics simulations with carefully designed collective variables to comprehensively map conformational space of 2D macromolecules. Our systematic exploration reveals three distinct metastable states, i.e., flat, fold and scroll conformations. Through detailed free energy analysis, we elucidate the delicate interplay between bending rigidity and interlayer adhesion that govern free energy surfaces of these conformations. Furthermore, we propose a temperature-modulated strategy to regulate conformational transitions among the three states. By decomposing the total free energy into entropic and enthalpic contributions, we quantitatively characterize the temperature-dependent thermodynamic driving forces underlying conformational transformations. This research establishes a robust computational framework for quantifying free energy and entropy associated with metastable conformations in 2D macromolecule systems. Our findings advance fundamental understanding of conformational transitions, regulation processes, and self-assembly behaviors in 2D macromolecular systems.

由于二维（2D）大分子的自由能表面本质上是复杂的，因此探索其构象景观带来了深刻的挑战。基于平衡分子动力学（MD）的传统计算方法的遍历探索有限，无法充分探索亚稳构象之间的能量景观和转变途径。在这项研究中，我们采用了精心设计的集体变量的良好调质元动力学模拟来全面绘制二维大分子的构象空间。我们的系统探索揭示了三种不同的亚稳态，即平面、折叠和涡旋构象。通过详细的自由能分析，我们阐明了支配这些构象的自由能表面的弯曲刚度和层间附着力之间微妙的相互作用。此外，我们提出了一种温度调制策略来调节三种状态之间的构象转变。通过将总自由能分解为熵和焓贡献，我们定量地描述了构象转化背后的温度依赖的热力学驱动力。本研究建立了一个强大的计算框架，用于量化二维大分子体系中与亚稳构象相关的自由能和熵。我们的发现促进了对二维大分子系统的构象转变、调节过程和自组装行为的基本理解。

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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 : 2025-11-13 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

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 : 2025-11-11 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

Viscoelasticity and crack growth in tanglemers 缠结物的粘弹性和裂纹扩展

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

Extreme Mechanics Letters

Pub Date : 2025-11-11 DOI: 10.1016/j.eml.2025.102418

Yu Zhou , Xianyang Bao , Zhigang Suo

A tanglemer is a polymer network in which chains are long, and entanglements greatly outnumber crosslinks. In a tanglemer, each chain is divided by crosslinks into many strands, and each strand is divided by entanglements into many segments. In synthesizing tanglemers, the crosslink density is readily varied, but the entanglement density is set by the chemistry of the polymer. Here we investigate how crosslink density affects the mechanical behavior of tanglemers. We find that viscoelasticity is unaffected by crosslink density when tanglemers are subject to stretches small enough without breaking strands. We then study crack growth in tanglemers under a static load. A load exists, called the slow-crack threshold, below which the crack does not grow. The threshold is high in a tanglemer of low crosslink density. Fast crack growth, however, is insensitive to crosslink density. We discuss how molecular mechanisms affect mechanical behavior.

缠结物是一种聚合物网络，其中的链很长，缠结远远超过交联。在缠结器中，每条链通过交联被分成许多股，每条股又通过缠结被分成许多片段。在合成缠结剂时，交联密度是容易变化的，但缠结密度是由聚合物的化学性质决定的。在这里，我们研究了交联密度如何影响缠结物的力学行为。我们发现，当缠结剂受到足够小的拉伸而不断裂链时，粘弹性不受交联密度影响。然后研究了静载荷作用下缠结材料的裂纹扩展。存在一个荷载，称为慢裂阈值，低于此荷载，裂纹不会扩展。在交联密度低的缠结物中，阈值较高。然而，快速裂纹扩展对交联密度不敏感。我们讨论分子机制如何影响力学行为。

引用次数: 0