Journal of The Mechanics and Physics of Solids最新文献_第10页

Imperfection-insensitive flexible random network materials with horseshoe microstructures 具有马蹄形微结构的对缺陷不敏感的柔性随机网络材料

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-11-19 DOI: 10.1016/j.jmps.2024.105968

Yue Xiao , Xiaonan Hu , Jun Wu , Zhangming Shen , Shuheng Wang , Shiwei Xu , Jianzhong Zhao , Jiahui Chang , Yihui Zhang

Flexible network materials with periodic constructions of bioinspired wavy microstructures are of focusing interest in recent years, because they combine outstanding mechanical performances of low elastic modulus, high stretchability, biomimetic stress-strain responses, and strain-limiting behavior. In practical applications (e.g., bio-integrated devices and tissue engineering), small holes are often strategically designed in flexible network materials to accommodate functional chips and other individual electronic components. The design of imperfection insensitive flexible network materials is therefore of pivotal importance. While random structural constructions are believed to play crucial roles in the excellent mechanical properties of many biological materials, the effect of randomness on mechanical performances of flexible network materials has not yet been explored. In this work, a class of two-dimensional (2D) flexible random network materials consisting of horseshoe microstructures is introduced. Their node distance distributions, which can be characterized by a parameter related to randomness, follow well the Weibull probability density function. Combined numerical and experimental studies were performed to elucidate the effect of randomness on nonlinear mechanical responses of flexible network materials. Simple analytical equations are obtained for their key mechanical properties (e.g., strength, stretchability, and initial modulus). Flexible random network materials (with randomness ≥ 0.4) were found to exhibit approximately isotropic J-shaped stress-strain responses, even in the high-strain regime. Finally, we study the reduction of stretchability and strength in random network materials induced by different types of imperfections (e.g., a missing filament, a missing node, or many missing filaments). In comparison to periodic network materials, random network materials (e.g., with randomness ≥ 0.6) show much smaller reductions of stretchability/strength when the imperfection appears, and are therefore more imperfection-insensitive. Such an imperfection-insensitive behavior can be mainly attributed to a relieved stress concentration around the imperfection of random network materials.

近年来，具有周期性生物启发波浪状微结构的柔性网络材料备受关注，因为它们兼具低弹性模量、高拉伸性、仿生物应力-应变响应和应变限制行为等出色的机械性能。在实际应用（如生物集成设备和组织工程）中，柔性网络材料通常会战略性地设计小孔，以容纳功能芯片和其他独立电子元件。因此，设计对缺陷不敏感的柔性网络材料至关重要。虽然随机结构构造被认为在许多生物材料的优异机械性能中发挥了关键作用，但随机性对柔性网络材料机械性能的影响尚未被探索。本文介绍了一类由马蹄形微结构组成的二维（2D）柔性随机网络材料。它们的节点间距分布可以用一个与随机性相关的参数来表征，并很好地遵循了 Weibull 概率密度函数。为了阐明随机性对柔性网络材料非线性机械响应的影响，我们进行了数值和实验相结合的研究。对其关键机械性能（如强度、拉伸性和初始模量）求出了简单的分析方程。研究发现，柔性随机网络材料（随机度≥ 0.4）表现出近似各向同性的 "J "形应力-应变响应，即使在高应变状态下也是如此。最后，我们研究了不同类型的缺陷（如缺少一根细丝、缺少一个节点或缺少许多细丝）对随机网络材料拉伸性和强度的影响。与周期性网络材料相比，随机网络材料（如随机度≥ 0.6）在出现缺陷时的拉伸性/强度降低幅度要小得多，因此对缺陷更不敏感。这种对缺陷不敏感的行为主要归因于随机网络材料缺陷周围的应力集中得到了缓解。

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引用次数: 0

Mechanical properties of modular assembled composite lattice architecture 模块化组装复合材料晶格结构的机械特性

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-11-18 DOI: 10.1016/j.jmps.2024.105967

Cheng Gong , Robert O. Ritchie , Xingyu Wei , Qingxu Liu , Jian Xiong

The layer-by-layer additive manufacturing approach results in the 3D printed composite lattice structure fails to exploit fiber reinforcement, thereby resulting in inferior mechanical qualities. To address this challenge, this study proposes a novel approach leveraging composite fused filament fabrication (FFF) printing to design modular assembled composite lattice structures. Initially, three high-performance lattice structures were transformed into discrete 2D components and assembled into 3D lattice structures. Subsequently, the mechanical properties of these structures were comprehensively assessed using theoretical, experimental, and finite element analysis methods. Finally, the comparison between the assembled structures and integrated printed lattice structures in terms of surface quality, mechanical properties, and manufacturability revealed significant advantages. The theoretical and finite element analyses accurately predicted the mechanical properties of the lattice structures. The lattice structures that were assembled in a modular way displayed an impressive 74% improvement in surface finish. Additionally, they showed peak strength increases of 140%, 27%, and 26%, respectively, for the mentioned types of topology. The energy absorption also increased significantly by 510.83%, 44.18%, and 30.24%. Furthermore, these assembled structures required less printing support materials, enhancing their manufacturability and cost-effectiveness. This new method of designing modular space structures goes beyond the limitations imposed by equipment by using high-performance topology. It allows for the construction of large-scale, lightweight space structures that offer excellent performance. This study explores innovative opportunities in the field of space manufacturing, offering potential implications for the development of lunar habitats, space telescopes, and space power stations.

逐层增材制造方法导致三维打印的复合材料晶格结构无法利用纤维加固，从而导致机械性能较差。为了应对这一挑战，本研究提出了一种利用复合材料熔融长丝制造（FFF）打印技术设计模块化组装复合材料晶格结构的新方法。首先，将三种高性能晶格结构转化为离散的二维组件，并组装成三维晶格结构。随后，使用理论、实验和有限元分析方法对这些结构的机械性能进行了全面评估。最后，在表面质量、机械性能和可制造性方面，对组装结构和集成打印晶格结构进行了比较，结果显示两者具有显著优势。理论和有限元分析准确预测了晶格结构的机械性能。以模块化方式组装的晶格结构在表面光洁度方面提高了 74%，令人印象深刻。此外，上述拓扑类型的峰值强度分别提高了 140%、27% 和 26%。能量吸收也显著增加了 510.83%、44.18% 和 30.24%。此外，这些组装结构所需的印刷辅助材料更少，从而提高了其可制造性和成本效益。这种设计模块化空间结构的新方法通过使用高性能拓扑结构，超越了设备的限制。它允许建造性能卓越的大型轻质空间结构。本研究探讨了空间制造领域的创新机会，为开发月球栖息地、空间望远镜和空间发电站提供了潜在的影响。

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引用次数: 0

The positioning of stress fibers in contractile cells minimizes internal mechanical stress 收缩细胞中应力纤维的定位可最大限度地减少内部机械应力

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-11-18 DOI: 10.1016/j.jmps.2024.105950

Lukas Riedel , Valentin Wössner , Dominic Kempf , Falko Ziebert , Peter Bastian , Ulrich S. Schwarz

The mechanics of animal cells is strongly determined by stress fibers, which are contractile filament bundles that form dynamically in response to extracellular cues. Stress fibers allow the cell to adapt its mechanics to environmental conditions and to protect it from structural damage. While the physical description of single stress fibers is well-developed, much less is known about their spatial distribution on the level of whole cells. Here, we combine a finite element method for one-dimensional fibers embedded in an elastic bulk medium with dynamical rules for stress fiber formation based on genetic algorithms. We postulate that their main goal is to achieve minimal mechanical stress in the bulk material with as few fibers as possible. The fiber positions and configurations resulting from this optimization task alone are in good agreement with those found in experiments where cells in 3D-scaffolds were mechanically strained at one attachment point. For optimized configurations, we find that stress fibers typically run through the cell in a diagonal fashion, similar to reinforcement strategies used for composite material.

动物细胞的机械结构在很大程度上由应力纤维决定，应力纤维是一种收缩丝束，根据细胞外线索动态形成。应力纤维使细胞的力学结构适应环境条件，并保护细胞免受结构损伤。虽然对单个应力纤维的物理描述已经非常完善，但对其在整个细胞水平上的空间分布却知之甚少。在这里，我们将嵌入弹性体介质中的一维纤维的有限元方法与基于遗传算法的应力纤维形成动力学规则相结合。我们推测，它们的主要目标是以尽可能少的纤维来实现散装材料中最小的机械应力。仅从这一优化任务中得出的纤维位置和配置，就与三维支架中的细胞在一个附着点上受到机械应力的实验结果十分吻合。对于优化配置，我们发现应力纤维通常以对角线方式穿过细胞，这与复合材料的加固策略类似。

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引用次数: 0

Latent-Energy-Based NNs: An interpretable Neural Network architecture for model-order reduction of nonlinear statics in solid mechanics 基于潜能的神经网络：用于减少固体力学非线性静力学模型阶次的可解释神经网络架构

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-11-17 DOI: 10.1016/j.jmps.2024.105953

Louen Pottier , Anders Thorin , Francisco Chinesta

Nonlinear mechanical systems can exhibit non-uniqueness of the displacement field in response to a force field, which is related to the non-convexity of strain energy. This work proposes a Neural Network-based surrogate model capable of capturing this phenomenon while introducing an energy in a latent space of small dimension, that preserves the topology of the strain energy; this feature is a novelty with respect to the state of the art. It is exemplified on two mechanical systems of simple geometry, but challenging strong nonlinearities. The proposed architecture offers an additional advantage over existing ones: it can be used to infer both displacements from forces, or forces from displacements, without being trained in both ways.

非线性机械系统在响应力场时会表现出位移场的非唯一性，这与应变能的非凸性有关。本研究提出了一种基于神经网络的代用模型，该模型能够捕捉这一现象，同时在小维度的潜空间中引入能量，并保留应变能的拓扑结构；这一特点在现有技术中是一种创新。我们在两个几何形状简单但非线性很强的机械系统上对其进行了演示。与现有的结构相比，所提出的结构还有一个优势：它既可以用于从力推断位移，也可以从位移推断力，而无需同时接受两种方式的训练。

引用次数: 0

Implicit implementation of a coupled transformation – plasticity crystal mechanics model for shape memory alloys that includes transformation rotations 形状记忆合金转化-塑性耦合晶体力学模型的隐式实施，包括转化旋转

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-11-17 DOI: 10.1016/j.jmps.2024.105964

Rupesh K. Mahendran , Surya R. Kalidindi , Aaron P. Stebner

A rate-dependent crystal-plasticity (CP) framework that captures the coupled phase transformation - plastic deformation behavior of shape memory alloys (SMAs) is presented. Here, different from previous models, the flow rule for martensitic phase transformation incorporates the entire deformation gradient for transformation, including the rotation. Predictions of transformation strain and variant selection of Nickel-Titanium (NiTi) using this model are directly compared with previous formulations that did not include the rotation. The results show that the rotation is essential to accurately calculate the single crystal and polycrystal micromechanics of variant selection and transformation strains of SMAs. The constitutive law formulation also includes current formulations for both slip and deformation twinning plasticity mechanisms, and the differences in transformation mechanisms are further shown to impact plasticity calculations through transformation-plasticity interactions. In addition to the advancement of the constitutive law, a computationally efficient implicit time integration scheme is given for numerical implementation and demonstrated using a user material subroutine (UMAT) in the commercial finite element code ABAQUS Standard. The proposed framework and the associated numerical protocols achieve stable solutions using strain increments on the order of

0.05

mm/mm in simulating inelastic deformations and strain increments

0.01

mm/mm in the elastic-inelastic transitions. Furthermore, the use of an analytic Jacobian results in stable convergence in fewer than 10 global Newton iterations while calculating solutions for elastic-inelastic transitions, making the computational benefits evident.

本文提出了一种与速率相关的晶体塑性（CP）框架，该框架可捕捉形状记忆合金（SMA）的相变-塑性变形耦合行为。与以前的模型不同，这里的马氏体相变流动规则包含了相变的整个变形梯度，包括旋转。使用该模型对镍钛合金（NiTi）的转变应变和变体选择进行的预测，与之前不包含旋转的公式进行了直接比较。结果表明，旋转对于准确计算 SMA 变体选择和转化应变的单晶和多晶微观力学至关重要。构成法公式还包括滑移和变形孪生塑性机制的当前公式，并进一步表明转化机制的差异会通过转化-塑性相互作用影响塑性计算。除了构造定律的进步之外，还给出了一种计算效率高的隐式时间积分方案，用于数值实施，并使用商业有限元代码 ABAQUS Standard 中的用户材料子程序 (UMAT) 进行了演示。在模拟非弹性变形时，所提出的框架和相关的数值协议可在应变增量为 0.05 mm/mm 和在弹性-非弹性转换时应变增量为 0.01 mm/mm 的情况下获得稳定的解决方案。此外，在计算弹性-非弹性转换的解时，使用解析雅各布因子可在不到 10 次全局牛顿迭代中实现稳定收敛，计算优势显而易见。

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引用次数: 0

Strain localization in rate sensitive porous ductile materials 速率敏感多孔韧性材料中的应变局部化

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-11-17 DOI: 10.1016/j.jmps.2024.105957

Alok Tripathy, Shyam M. Keralavarma

Ductile failure by the onset of strain localization in rate sensitive porous materials is investigated using a linear perturbation stability analysis. A micromechanics-based constitutive model accounting for inhomogeneous yielding at the micro-scale, due to plastic strain concentration in the inter-void ligaments, is used. Strain and strain rate hardening of the material is accounted for using a phenomenological viscoplastic extension of the model. Unlike in earlier studies employing a rate-dependent model, an analytical closed form expression for the critical value of the hardening modulus at the onset of localization is derived. The predicted shape of the failure locus under proportional loading is shown to be consistent with known results in the literature for the loading path dependence of ductile failure. The model predicted failure loci are validated by comparison with mesoscopic unit cell model simulations of void growth in a viscoplastic power law hardening material. It is shown that the failure strains predicted by the model as a function of the hardening parameters are in good agreement with the strains to the onset of elastic unloading in the cell model simulations, signifying the onset of void coalescence at the micro-scale.

通过线性扰动稳定性分析，研究了速率敏感多孔材料中应变局部化的韧性破坏。采用了一个基于微观力学的构成模型，该模型考虑到了由于空隙间韧带的塑性应变集中而导致的微观尺度上的不均匀屈服。材料的应变和应变速率硬化是通过该模型的现象学粘塑性扩展来考虑的。与之前采用速率依赖模型的研究不同，该模型推导出了局部硬化开始时硬化模量临界值的分析封闭式表达式。结果表明，在比例加载条件下预测的破坏位置形状与文献中已知的韧性破坏加载路径依赖性结果一致。通过与粘塑性幂律硬化材料中空隙增长的介观单元模型模拟进行比较，验证了模型预测的破坏位置。结果表明，模型预测的失效应变作为硬化参数的函数，与晶胞模型模拟中弹性卸载开始时的应变非常吻合，这标志着微观尺度上空隙凝聚的开始。

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引用次数: 0

Graph neural networks for strut-based architected solids 用于基于支柱的结构实体的图神经网络

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-11-16 DOI: 10.1016/j.jmps.2024.105966

I. Grega , I. Batatia , P.P. Indurkar , G. Csányi , S. Karlapati , V.S. Deshpande

Machine learning methods for strut-based architected solids are attractive for reducing computational costs in optimisation calculations. However, the space of all realizable strut-based periodic architected solids is vast: not only can the number of nodes, their positions and the radii of the struts be changed but the topological variables such as the connectivity of the nodes brings significant complexity. In this work, we first examine the structure-property relationships of a large dataset of strut-based architected solids (lattices). We enrich the dataset by perturbing nodal positions and observe four classes of mechanical behaviour. A graph neural network (GNN) method is then proposed that directly describes the topology of the strut-based architected solid as a graph. The differentiating feature of our work is that key physical principles are embedded into the GNN architecture. In particular, the GNN model predicts fourth-order tensor with the required major and minor symmetries. The predictions are equivariant to rigid body and self-similar transformations, invariant to the choice of unit cell and constrained to provide a positive semi-definite stiffness tensor. We further demonstrate that augmenting the training dataset with nodal perturbations enables the model to better generalize to unseen lattice topologies.

针对基于支柱的结构实体的机器学习方法对于降低优化计算的计算成本很有吸引力。然而，所有可实现的基于支柱的周期性拱形结构实体的空间是巨大的：不仅节点数量、节点位置和支柱半径可以改变，而且拓扑变量（如节点的连通性）也带来了巨大的复杂性。在这项工作中，我们首先研究了大量基于支柱的架构实体（网格）数据集的结构-属性关系。我们通过扰动节点位置来丰富数据集，并观察到四类机械行为。然后，我们提出了一种图神经网络 (GNN) 方法，该方法可直接将基于支柱的拱形实体拓扑结构描述为一个图。我们工作的与众不同之处在于将关键物理原理嵌入到 GNN 架构中。特别是，GNN 模型预测了具有所需主要和次要对称性的四阶张量。这些预测对刚体和自相似变换具有等变性，对单元格的选择具有不变性，并受限于提供正半有限刚度张量。我们进一步证明，用节点扰动来增加训练数据集能使模型更好地泛化到未见过的晶格拓扑结构。

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引用次数: 0

Stochastic generalized standard materials and risk-averse effective behavior 随机广义标准材料和规避风险的有效行为

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-11-16 DOI: 10.1016/j.jmps.2024.105952

Jeremy Bleyer

In this work, we develop a theoretical formulation for describing dissipative material behaviors in a stochastic setting, using the framework of Generalized Standard Materials (GSM). Our goal is to capture the variability inherent in the material model while ensuring thermodynamic consistency, by employing the mathematical framework of stochastic programming. We first show how average behaviors can be computed using the expected value of the free energy and dissipation pseudo-potentials. We then introduce the concept of a risk-averse effective measure, which provides both an optimistic and a pessimistic estimate of the uncertain material behavior. To this end, we utilize the Conditional Value-at-Risk, a widely used risk measure in mathematical finance. We also demonstrate how these concepts can be extended to variational problems at the structure scale, allowing us to compute the effective response of a structure composed of a stochastic material.

在这项工作中，我们利用广义标准材料（GSM）框架，开发了一种在随机环境下描述耗散材料行为的理论公式。我们的目标是通过采用随机编程的数学框架，在确保热力学一致性的同时，捕捉材料模型中固有的可变性。我们首先展示了如何利用自由能和耗散伪势的预期值计算平均行为。然后，我们引入了风险规避有效度量的概念，它能对不确定的材料行为做出乐观和悲观的估计。为此，我们利用了条件风险值，这是数学金融中广泛使用的一种风险度量。我们还演示了如何将这些概念扩展到结构尺度的变分问题，从而计算由随机材料组成的结构的有效响应。

引用次数: 0

Mechanics of electroadhesion of polyelectrolyte hydrogel heterojunctions enabled by ionic double layers 离子双层促成的聚电解质水凝胶异质结的电粘附机理

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-11-15 DOI: 10.1016/j.jmps.2024.105960

Zheyu Dong, Zhi Sheng, Zihang Shen, Shaoxing Qu, Zheng Jia

In recent years, soft materials with reversible adhesion have come to the fore as a promising avenue of research. Compared to other reversible adhesion methods, electroadhesion enabled by the formation of ionic double layer (IDL) has been widely used due to its simplicity, low energy consumption, fast response, and reversibility. Despite the extensive experimental studies and qualitative mechanistic explanations, there remains a dearth of theoretical studies on this topic, particularly regarding the development of theoretical mechanics models. Our study aims to address this gap by establishing a mechanics model of IDL-enabled electroadhesion between soft materials. We specifically focus on modeling the low-voltage electroadhesion of heterojunctions between two polyelectrolyte hydrogels. The model decomposes the electroadhesion formation into two successive physical processes. First, under appropriate bias conditions, the applied voltage drives the mobile ions in each polyelectrolyte hydrogel to migrate toward the electrode, resulting in the formation of an IDL at the heterojunction interface and the generation of a potent built-in electric field inside the IDL. Second, driven by the strong built-in electric field of IDL, the dangling charged chains of the two polyelectrolyte hydrogels begin to cross the heterojunction interface and penetrate into the opposite hydrogel matrix to form ionic bonds with the oppositely-charged chains, resulting in a bridging network that sutures the interface. As a result, the electrostatic interactions inside the IDL as well as the bridging network across the interface leads to the electroadhesion of polyelectrolyte hydrogel heterojunctions. The modeling results show that the IDL thickness, the IDL electric field density, and the electroadhesion strength increase with the applied voltage. We also experimentally conduct the electroadhesion tests, and the measurements of electroadhesion strength quantitatively match the modeling results well. For the first time, we reveal the underlying mechanism of IDL-driven electroadhesion by establishing a theoretical mechanics model. We anticipate that our mechanics model can shed light on the design, optimization, and control of the electroadhesion of soft-material heterojunctions.

近年来，具有可逆附着力的软性材料作为一种前景广阔的研究方向备受瞩目。与其他可逆粘附方法相比，离子双层（IDL）形成的电粘附因其简单、能耗低、反应快和可逆性而得到广泛应用。尽管有大量的实验研究和定性的机理解释，但有关这一主题的理论研究仍然十分匮乏，尤其是在理论力学模型的开发方面。我们的研究旨在通过建立软材料间 IDL 启用的电粘合力学模型来填补这一空白。我们特别关注两个聚电解质水凝胶之间异质结的低压电去粘性建模。该模型将电粘连的形成分解为两个连续的物理过程。首先，在适当的偏压条件下，外加电压会驱动每个聚电解质水凝胶中的移动离子向电极迁移，从而在异质结界面上形成 IDL，并在 IDL 内部产生强大的内置电场。其次，在 IDL 强内置电场的驱动下，两种聚电解质水凝胶的悬垂带电链开始穿过异质结界面，并渗透到相反的水凝胶基质中，与带相反电荷的链形成离子键，从而形成缝合界面的桥接网络。因此，IDL 内部的静电相互作用以及跨越界面的桥接网络导致了聚电解质水凝胶异质结的电粘连。建模结果表明，IDL 厚度、IDL 电场密度和电粘附强度随施加电压的增加而增加。我们还通过实验进行了电粘附测试，电粘附强度的测量结果与建模结果在定量上非常吻合。通过建立理论力学模型，我们首次揭示了 IDL 驱动电泳的内在机理。我们期待我们的力学模型能够为软材料异质结的电泳设计、优化和控制提供启示。

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引用次数: 0

Unraveling the molecular mechanisms of membrane rupture: Insights from all-atom simulations and theoretical modeling 揭示膜破裂的分子机制：全原子模拟和理论建模的启示

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-11-15 DOI: 10.1016/j.jmps.2024.105958

Panpan Zhu , Ji Lin , Yimou Fu , Chun Shen , Haofei Zhou , Shaoxing Qu , Huajian Gao

Cell membrane rupture occurs universally and is long thought to be the terminal event of cell death; however, there is an inadequate understanding of the microscopic mechanisms of membrane rupture at the molecular level. In this study, we investigated the rupture mechanism of two model membranes, 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) and cholesterol bilayer membranes, under surface tension by all-atom molecular simulations and theoretical modeling. Under surface tension, the tail chains of POPC molecules become disordered, leading to ductile membrane deformation, while cholesterol membranes display limited deformation before rupture. We analyzed the orientation of tail chains and the internal stresses within the membranes, revealing that the mutual attraction among different tail chains and the resulting stress peak in the tail region of the membrane play substantial roles in the membrane rupture process. Based on these physical insights, we proposed a theoretical model that incorporates an internal variable of tail chain orientation to capture the variations in strain and orientation of different membrane components under varying surface tensions. The critical rupture threshold predicted by our theoretical model aligns well with the simulation results, demonstrating a brittle to ductile transition for membranes with different cholesterol contents. Our study unravels the impact of tail chain orientation and internal stress on membrane mechanics, which deepens the understanding of the microscale mechanisms underlying membrane rupture.

细胞膜破裂是普遍发生的现象，长期以来被认为是细胞死亡的终结事件；然而，人们对膜破裂在分子水平上的微观机制认识不足。在这项研究中，我们通过全原子分子模拟和理论建模研究了两种模型膜--1-棕榈酰-2-油酰-磷脂酰胆碱（POPC）和胆固醇双层膜--在表面张力下的破裂机制。在表面张力作用下，POPC 分子的尾链变得无序，导致膜发生韧性变形，而胆固醇膜在破裂前的变形有限。我们分析了尾链的取向和膜内的内应力，发现不同尾链之间的相互吸引以及由此产生的膜尾部应力峰在膜破裂过程中起着重要作用。基于这些物理观点，我们提出了一个理论模型，其中包含了尾链取向的内部变量，以捕捉不同表面张力下不同膜成分的应变和取向变化。我们的理论模型所预测的临界破裂阈值与模拟结果非常吻合，证明了不同胆固醇含量的膜从脆性到韧性的转变。我们的研究揭示了尾链取向和内应力对膜力学的影响，加深了对膜破裂微观机制的理解。

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引用次数: 0