Extreme Mechanics Letters最新文献_第6页

Pull-in instability of droplet amplified electrostatic actuators considering dielectric barrier discharge 考虑介质阻挡放电的液滴放大静电致动器的拉入不稳定性

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

Extreme Mechanics Letters

Pub Date : 2025-08-19 DOI: 10.1016/j.eml.2025.102398

Delei Qin , Jianglong Guo , Yanju Liu , Jinsong Leng

Liquid-amplified electrostatic actuators can generate greater forces than conventional ones which use air as the dielectric between two electrodes. Dielectric droplet amplified electrostatic actuators, a major type of liquid amplified electrostatic actuator, can be used to provide powerful, fast, energy-efficient, and lightweight actuations. However, the mechanical response of droplet amplified electrostatic actuator and the liquid amplification mechanism remain unexplored in a comprehensive way. Here we present a quasi-static model for droplet amplified electrostatic actuators considering dielectric barrier discharge and capillary force. The Galerkin method and the Newton method were used to numerically solve the model. A customized pull-in voltage measurement setup was established to verify the numerical results and the main influencing parameters were studied. The experimentally validated model can be used to accurately predict the quasi-static response and pull-in voltage of droplet amplified electrostatic actuators. This work highlights that the liquid amplification comes mainly from higher permittivity than air, dielectric barrier discharge elimination, and capillary force, due to the use of liquid dielectrics instead of air. The results in this work may provide useful insights into droplet amplified electrostatic actuator structural optimization, control, and application.

液体放大静电致动器比传统的使用空气作为两个电极之间的电介质的致动器产生更大的力。介质液滴放大式静电执行器是液体放大式静电执行器的主要类型，可以提供强大、快速、节能、轻便的执行器。然而，液滴放大静电执行器的力学响应和液体放大机理尚未得到全面的探讨。本文建立了考虑介质阻挡放电和毛细力的液滴放大静电致动器的准静态模型。采用伽辽金法和牛顿法对模型进行了数值求解。建立了自定义的拉入电压测量装置，对数值结果进行了验证，并对主要影响参数进行了研究。实验验证的模型可以准确预测液滴放大静电致动器的准静态响应和拉入电压。这项工作强调了液体放大主要来自于比空气更高的介电常数，介质阻挡放电消除和毛细力，由于使用液体介质而不是空气。研究结果为液滴放大静电致动器的结构优化、控制和应用提供了有益的启示。

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引用次数: 0

Conditional stability in metamaterials: Experiments, modeling, and 3D design 超材料的条件稳定性：实验、建模和3D设计

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

Extreme Mechanics Letters

Pub Date : 2025-08-07 DOI: 10.1016/j.eml.2025.102393

G. Risso , L. Pesaresi , A.S. Meeussen , K. Bertoldi

The mechanical properties of metamaterials are typically governed by their architecture in the undeformed configuration, which limits their adaptability. Recent work has shown that interactions between structural components with strongly nonlinear responses can reshape the system’s energy landscape. For instance, a structure composed of four von Mises trusses coupled through an elastic matrix exhibits conditional stability: stability along one principal direction can be tuned on demand by modifying the metamaterial’s topological state along the orthogonal direction. Here, we systematically investigate the mechanical response of such conditionally stable structures through a combination of experiments, Finite Element simulations, and analytical modeling. Building on these insights, we propose a strategy to extend conditional stability to a three-dimensional architecture, demonstrating its potential for reprogrammable energy absorption.

超材料的力学性能通常由其未变形的结构决定，这限制了它们的适应性。最近的研究表明，具有强烈非线性响应的结构部件之间的相互作用可以重塑系统的能量景观。例如，由四个von Mises桁架通过弹性矩阵耦合组成的结构表现出条件稳定性：沿着一个主方向的稳定性可以根据需要通过修改沿着正交方向的超材料拓扑状态来调整。在这里，我们通过实验、有限元模拟和分析建模相结合，系统地研究了这种条件稳定结构的力学响应。基于这些见解，我们提出了一种将条件稳定性扩展到三维结构的策略，展示了其可重新编程能量吸收的潜力。

引用次数: 0

Model elasto-plastic metamaterials as generic computing platforms 模拟弹塑性超材料作为通用计算平台

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

Extreme Mechanics Letters

Pub Date : 2025-08-06 DOI: 10.1016/j.eml.2025.102390

Laura Michel, Frédéric Lechenault

Mechanical metamaterials are engineered materials constructed from elementary building blocks, typically arranged in regular patterns. These materials are generally studied for their effective properties, which are determined by the arrangement of their building blocks rather than the material they are made of. However, new functionalities are emerging, with mechanical metamaterials now exhibiting capabilities similar to conventional computers. For instance, they have been used to store binary data and even perform simple computations such as small binary additions and multiplications. These computing devices could be valuable in extreme environments where traditional electronic systems fail to operate. Moreover, they can process data autonomously without requiring a sustained power source. Despite this potential, there are no established design principles for systematically developing such computational materials. In this work, we explore the use of a model elasto-plastic metamaterial – a two-dimensional lattice composed of linear and bistable spring–mass systems – for executing sequential algorithms. While previous studies on mechanical computing mostly focused on small devices, we show that the lattice can be crafted to execute algorithms with many steps and large inputs, such as

n

-bit binary number additions. To our knowledge, this model has never been used for computational purposes before. This work thus offers a novel perspective on such models, proposing them as generic computing platforms that can be harnessed to design new computational materials.

机械超材料是由基本构件组成的工程材料，通常以规则的模式排列。人们通常研究这些材料的有效性能，这些性能是由它们的组成部分的排列决定的，而不是由它们的材料决定的。然而，新的功能正在出现，机械超材料现在表现出与传统计算机相似的能力。例如，它们被用来存储二进制数据，甚至执行简单的计算，如小的二进制加法和乘法。这些计算设备在传统电子系统无法运行的极端环境中可能很有价值。此外，它们可以在不需要持续电源的情况下自主处理数据。尽管有这种潜力，但目前还没有确定的设计原则来系统地开发这种计算材料。在这项工作中，我们探索了使用模型弹塑性超材料-由线性和双稳态弹簧质量系统组成的二维晶格-来执行顺序算法。虽然先前对机械计算的研究主要集中在小型设备上，但我们表明，晶格可以精心设计，以执行具有许多步骤和大输入的算法，例如n位二进制数加法。据我们所知，这个模型以前从未被用于计算目的。因此，这项工作为这些模型提供了一个新颖的视角，提出它们可以作为通用的计算平台，用于设计新的计算材料。

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引用次数: 0

Peeling a rigid sphere from a stretched rubber substrate 从拉伸的橡胶基材上剥下坚硬的球体

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

Extreme Mechanics Letters

Pub Date : 2025-07-26 DOI: 10.1016/j.eml.2025.102381

Christopher W. Barney , Yue (Luna) Zheng

Polymer coatings are an important technology where pre-stresses can develop during draping, drying, and cooling. This paper aims to quantify the impact that these stresses have on the indentation response. Spherical probe indentation is performed on a stretched and unstretched substrate where the evolution of the contact area is monitored. Consistent with previous works, it is found that the contact area becomes elliptical on stretched substrates. Further, it is observed that this ellipse dynamically evolves during the indentation and peel process. This change in contact area upon stretching is found to increase the apparent stiffness and decrease the adhesive response.

聚合物涂层是一项重要的技术，可以在悬垂、干燥和冷却过程中产生预应力。本文旨在量化这些应力对压痕响应的影响。在拉伸和未拉伸的基板上执行球形探头压痕，其中监测接触区域的演变。与以往的工作一致，发现在拉伸基底上接触面积变为椭圆形。此外，还观察到该椭圆在压痕和剥离过程中动态演变。发现拉伸时接触面积的变化增加了表观刚度，降低了粘接响应。

引用次数: 0

Non-local elastic lattices with PT-symmetry and time modulation: From perfect trapping to the wave boomerang effect 具有pt对称和时间调制的非局部弹性晶格：从完美的俘获到波回旋效应

IF 4.3 3区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Extreme Mechanics Letters

Pub Date : 2025-07-25 DOI: 10.1016/j.eml.2025.102383

Emanuele Riva

Wave motion is fundamentally constrained by the dispersion properties of the medium, often making it challenging — or even impossible — to guide wave packets along desired trajectories, particularly when wave inversion is required. The paper illustrates how one-dimensional (1D) and two-dimensional (2D) non-Hermitian elastic lattices with time-varying non-local feedback interactions offer unprecedented wave guidance. By relaxing the constraint of Hermiticity while preserving

PT

-symmetry of the nonlocal interactions, it is herein built a framework where the dispersion transitions from positive to negative group velocity, passing through an intermediate regime characterized by a perfectly flat band across all momenta. This effect, realized within the unbroken

PT

-symmetric phase, is further enhanced by the time modulation of lattice parameters, thereby unlocking functionalities such as perfect trapping, where a wave packet is intentionally stopped, and the wave boomerang effect, where the wave packet is reversed or guided back to its initial position. The framework presented in this paper unlocks opportunities that extend beyond wave guidance, including information processing through dispersion engineering in elastic media.

波的运动基本上受到介质色散特性的限制，这使得引导波包沿着期望的轨迹变得具有挑战性，甚至是不可能的，特别是当需要进行波的反演时。本文阐述了具有时变非局部反馈相互作用的一维（1D）和二维（2D）非厄米弹性晶格如何提供前所未有的波导。在保持非局域相互作用pt对称性的同时，通过放宽hermite约束，本文建立了一个色散从正群速度向负群速度转变的框架，该框架通过一个中间区域，其特征是在所有动量上都有一个完美的平坦带。这种效应是在完整的pt对称相位中实现的，通过晶格参数的时间调制进一步增强，从而解锁诸如完美捕获（波包被故意停止）和波回旋效应（波包被逆转或引导回其初始位置）等功能。本文提出的框架揭示了超越波导的机会，包括通过弹性介质中的色散工程进行信息处理。

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引用次数: 0

Modeling the hardening behavior of rubber-like elastomers under high hydrostatic pressure 模拟类橡胶弹性体在高静水压力下的硬化行为

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

Extreme Mechanics Letters

Pub Date : 2025-07-25 DOI: 10.1016/j.eml.2025.102397

Yukai Zhao , Xuxu Yang , Fanghao Zhou , Siyang Li , Tiefeng Li

Elastomers are known to exhibit an increase in elastic modulus under high hydrostatic pressure. To capture this hardening effect, a novel compressible hyperelastic model, extending the framework of Neo-Hookean model, is proposed. This model links volume reduction with microscale properties to describe the pressure-induced increase in effective shear modulus. By measuring the effective shear modulus and fractional volume under varying hydrostatic pressures, the change in elastic modulus for polydimethylsiloxane (PDMS) is quantified. The model is implemented into the commercial finite element software Abaqus via a UHYPER subroutine. Simulations based on the extended Neo-Hookean model accurately reproduce experimental deformations, outperforming the Neo-Hookean model, which showed significant deviations. Specimens with different PDMS mass ratios were tested to investigate the relationship between the hardening factor and microscale properties. The proposed model provides valuable insights for device design and applications in high-pressure environments.

已知弹性体在高静水压力下表现出弹性模量的增加。为了捕捉这种硬化效应，提出了一种新的可压缩超弹性模型，扩展了Neo-Hookean模型的框架。该模型将体积减小与微尺度性质联系起来，以描述压力引起的有效剪切模量增加。通过测量不同静水压力下聚二甲基硅氧烷（PDMS）的有效剪切模量和分数体积，量化了其弹性模量的变化。该模型通过UHYPER子程序在商用有限元软件Abaqus中实现。基于扩展Neo-Hookean模型的仿真准确再现了实验变形，优于Neo-Hookean模型，但存在明显的偏差。通过不同PDMS质量比的试样试验，研究了硬化因子与微观性能的关系。所提出的模型为高压环境下的设备设计和应用提供了有价值的见解。

引用次数: 0

Inverse design of mechanical metamaterials balancing manufacturability and compactness: A case study on lattice cells 平衡可制造性和紧凑性的机械超材料的反设计：以晶格单元为例

IF 4.3 3区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Extreme Mechanics Letters

Pub Date : 2025-07-25 DOI: 10.1016/j.eml.2025.102395

Jiacheng Xue, Hanmeng Bao, Tengfei Liu, Lingling Wu, Xiaoyong Tian, Dichen Li

Mechanical metamaterials are artificially engineered structures designed to exhibit unique and extraordinary mechanical properties. In recent years, machine learning has provided a more efficient and systematic approach, enabling inverse design of mechanical metamaterials, which allow for a broader exploration of material properties and support the integration of multifunctionality, significantly speeding up the design process. Despite the many advantages of inverse design, metamaterials often involve a trade-off between competing performance metrics-such as manufacturability and structural compactness. Furthermore, these trade-offs should be dynamically adjusted based on different additive manufacturing conditions. To address this, we proposed a regressional and conditional generative adversarial network based multi-objective (RCGAN-MO) architecture, which simultaneously handles the inverse design and adjustable multi-objective optimization of mechanical metamaterials. The RCGAN-MO includes two trained neural networks: a generator and a predictor, along with a weighted multi-objective optimizer. As a case study, the RCGAN-MO architecture is applied to the inverse design of the relative compressive elastic modulus for a metamaterial, and metamaterials with different weight vector values in the multi-objective optimizer are achieved through 3D printed prototypes. This approach achieves high accuracy and could adjust the importance of manufacturability and compactness, offering a flexible, scalable solution for engineering metamaterials tailored to practical application demands.

机械超材料是人工设计的结构，旨在表现出独特和非凡的机械性能。近年来，机器学习提供了一种更有效、更系统的方法，使机械超材料的逆设计成为可能，从而可以更广泛地探索材料特性，并支持多功能的集成，大大加快了设计过程。尽管逆向设计有许多优点，但超材料通常涉及到竞争性能指标之间的权衡，例如可制造性和结构紧凑性。此外，这些权衡应根据不同的增材制造条件进行动态调整。为了解决这一问题，我们提出了一种基于回归和条件生成对抗网络的多目标（RCGAN-MO）架构，该架构同时处理机械超材料的逆设计和可调多目标优化。RCGAN-MO包括两个经过训练的神经网络：一个生成器和一个预测器，以及一个加权多目标优化器。将RCGAN-MO体系结构应用于某超材料的相对压缩弹性模量反设计中，通过3D打印原型实现了多目标优化器中具有不同权重向量值的超材料。该方法实现了高精度，可以调整可制造性和紧凑性的重要性，为工程超材料提供了一个灵活的、可扩展的解决方案，以满足实际应用需求。

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引用次数: 0

Hard-to-soft part ratios in natural crawlers inform hybrid robotic design 自然履带的软硬零件比为混合动力机器人的设计提供了依据

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

Extreme Mechanics Letters

Pub Date : 2025-07-25 DOI: 10.1016/j.eml.2025.102394

Jiayi Lei , Changhong Linghu , Min Pan , K. Jimmy Hsia

Most robots to date consist of either entirely hard parts or entirely soft parts. Nature, however, achieves a balance between hard and soft components, offering both adaptability and strength for adequate load-carrying capacity and locomotion in diverse environments. Inspired by nature, hybrid robotic designs, combining the flexibility of soft robots with the control and load-bearing capacity of hard robots, are being pursued. However, a proper range of the Hard-to-Soft Part Ratio (H2S-R) for the desirable performance of hybrid robots remains unclear. With a focus on crawlers, this study comprehensively compiles the H2S-R in crawling animals of four locomotion mechanisms: two-anchor, peristaltic, undulatory, and multi-legged crawling, and analyzes the trends and scaling in their performances. Results show distinct ranges of H2S-R in natural crawlers: 0.0005–0.003 for two-anchor crawlers, 0.08–0.09 for peristaltic, 0.02–0.08 for undulatory, and 1.0–2.4 for multi-legged. Within these ranges, except for the undulatory locomotion, increasing the H2S-R generally enhances their normalized crawling speed measured in body-lengths per second. Data for natural crawlers also show different ranges of normalized speeds as well as distinct scaling laws for different mechanisms. Comparisons with the performance of natural crawlers indicate that robotic crawlers have yet to achieve their full potential in crawling speed. This study provides guidelines for designing bio-inspired hybrid robots with potential applications in search and rescue, environmental monitoring, space exploration, and medical robotics.

迄今为止，大多数机器人要么完全由硬部件组成，要么完全由软部件组成。然而，大自然在硬构件和软构件之间取得了平衡，在不同的环境中提供了足够的承载能力和运动能力的适应性和强度。受大自然的启发，混合机器人的设计，将软机器人的灵活性与硬机器人的控制和承载能力相结合，正在被追求。然而，对于混合机器人理想性能的软硬零件比（H2S-R）的适当范围仍不清楚。本研究以爬行动物为研究对象，全面梳理了双锚爬行、蠕动爬行、波动爬行和多足爬行四种运动机制下爬行动物的H2S-R，并分析了其表现的趋势和尺度。结果表明，自然爬行动物的H2S-R含量范围明显不同：双锚爬行动物为0.0005-0.003，蠕动爬行动物为0.08-0.09，波动爬行动物为0.02-0.08，多足爬行动物为1.0-2.4。在这些范围内，除了波动运动外，增加H2S-R通常会提高它们的标准化爬行速度（以体长/秒为单位）。自然爬行器的数据也显示出不同的归一化速度范围以及不同机制的不同标度规律。与自然爬行器的性能比较表明，机器人爬行器尚未充分发挥其爬行速度的潜力。该研究为仿生混合机器人的设计提供了指导，这些机器人在搜救、环境监测、空间探索和医疗机器人等领域具有潜在的应用前景。

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引用次数: 0

Determination of high strain-rate, viscoelastic material properties of soft solids using inertial microcavitation in a thin layer 利用惯性微空化在薄层中测定软固体的高应变率粘弹性材料性能

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

Extreme Mechanics Letters

Pub Date : 2025-07-25 DOI: 10.1016/j.eml.2025.102378

Surya Sidhartha Kolluri , Elizabeth C. Bremer-Sai , Anastasia Tzoumaka , Christian Franck , David L. Henann

Determining the high strain-rate mechanical properties of soft hydrogels and biological tissues is important for a number of biological and engineering applications but remains challenging due to the high compliance of these materials. Inertial microcavitation rheometry (IMR) is a recently developed experimental technique aimed at addressing this need and requires the optical resolution of cavitation bubble kinematics via high-speed videography. While this approach works well for optically transparent samples of dimensions much larger than the typical micron to sub-millimeter bubble sizes, IMR is challenged in highly light scattering media, such as nearly opaque tissues. One remedy to decrease the light scattering within a tissue is to prepare a thinner sample, which facilitates successful recording of the cavitation bubble dynamics. However, the thickness of the required thin samples can approach the size of the microbubbles, and the resulting confinement of the soft material layer between two boundaries changes the fundamental character of the assumed nearly infinite domain of the IMR theoretical framework, leading to erroneous material property estimates. To address this issue and to facilitate successful application of IMR to thin layers of soft materials under confinement, we developed a modified, thin-layer IMR approach for the accurate determination of high strain-rate viscoelastic material properties of soft solids that utilizes axisymmetric finite-element simulations of bubble dynamics in a thin layer. The approach is applied to two transparent, benchmark gels: 6% and 14% gelatin, and the material parameters estimated using the thin-layer IMR approach are validated against experimental data for isolated, spherical bubbles and oversized bubbles in a thin layer. The thin-layer IMR approach provides a robust methodology for applying IMR to nearly opaque, soft materials, such as tissues.

确定软水凝胶和生物组织的高应变率机械性能对于许多生物和工程应用非常重要，但由于这些材料的高度顺应性，仍然具有挑战性。惯性微空化流变学（IMR）是一种最近发展起来的实验技术，旨在解决这一需求，并要求通过高速摄像的光学分辨率的空化气泡的运动学。虽然这种方法适用于尺寸比典型的微米到亚毫米气泡尺寸大得多的光学透明样品，但IMR在高度光散射介质（例如几乎不透明的组织）中受到挑战。减少组织内光散射的一种补救措施是制备更薄的样品，这有助于成功记录空化气泡动力学。然而，所需薄样品的厚度可以接近微泡的大小，并且由此产生的两个边界之间的软材料层的限制改变了假设的IMR理论框架的近无限域的基本特征，导致错误的材料性能估计。为了解决这一问题，并促进IMR在约束下的薄层软材料中的成功应用，我们开发了一种改进的薄层IMR方法，用于精确测定软固体的高应变率粘弹性材料特性，该方法利用薄层中气泡动力学的轴对称有限元模拟。该方法应用于两种透明的基准凝胶：6%和14%明胶，使用薄层IMR方法估计的材料参数与薄层中孤立的球形气泡和超大气泡的实验数据进行了验证。薄层IMR方法为将IMR应用于几乎不透明的软材料（如组织）提供了一种强大的方法。

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引用次数: 0

Multiscale structure-mechanical property relationship and data-driven design of ultra-high temperature ceramics: A review 超高温陶瓷的多尺度结构-力学性能关系与数据驱动设计综述

IF 4.3 3区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Extreme Mechanics Letters

Pub Date : 2025-07-24 DOI: 10.1016/j.eml.2025.102392

Xiaoqian Gao , Li Chen , Runkai Liu , Jing Wan , Huasong Qin , Yilun Liu

Ultra-high temperature ceramics (UHTCs) exhibit exceptional melting points, superior oxidation resistance, and outstanding ablation performance, positioning them as indispensable materials for extreme-environment applications. However, their inherent brittleness, high density, limited elasticity, and poor fatigue resistance restrict broader implementation. This review presents a rigorous, multiscale examination of interrelationships between UHTC structural characteristics and mechanical behaviors, addressing critical knowledge gaps in failure mechanisms and state-of-the-art design of strengthening and toughening strategies. The analysis commences with crystal-chemical principles and progresses through salient microstructural and mesostructural characteristics, followed by an exploration of thermally induced deformation and structural evolution at elevated temperatures. The dominated factors in mechanical degradation and corresponding strengthening and toughening mechanisms across nanoscale, microscale, and mesoscale levels are systematically dissected. Furthermore, we highlight recent advances in high-throughput screening within materials genome engineering and the integration of machine learning (ML) for rapid property prediction and structural optimization of UHTCs. Finally, prospective multiscale design strategies are proposed to synergistically optimize the balance of strength and toughness in UHTCs.

超高温陶瓷（UHTCs）具有卓越的熔点，卓越的抗氧化性和出色的烧蚀性能，使其成为极端环境应用中不可或缺的材料。然而，它们固有的脆性、高密度、有限弹性和较差的抗疲劳性限制了它们的广泛应用。本文对UHTC结构特征和力学行为之间的相互关系进行了严格的、多尺度的研究，解决了失效机制和最先进的强化和增韧策略设计方面的关键知识空白。分析从晶体化学原理开始，通过突出的微观结构和细观结构特征进行进展，随后探索高温下的热致变形和结构演变。在纳米尺度、微尺度和中尺度水平上系统剖析了机械降解的主要因素和相应的强化和增韧机制。此外，我们强调了材料基因组工程中高通量筛选的最新进展，以及机器学习（ML）的集成，用于UHTCs的快速性能预测和结构优化。最后，提出了未来的多尺度设计策略，以协同优化UHTCs的强度和韧性平衡。

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引用次数: 0