【新文速递】2024年1月26日固体力学SCI期刊最新文章

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今日更新：Journal of the Mechanics and Physics of Solids 1 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 2 篇

Journal of the Mechanics and Physics of Solids

Effective isometries of periodic shells

Hussein Nassar, Andrew Weber

doi:10.1016/j.jmps.2024.105553

周期壳层的有效等距

We argue that the standard classification of isometric deformations into infinitesimal v.s. finite is inadequate for the study of compliant shell mechanisms. Indeed, many compliant shells, particularly ones that are periodically corrugated, exhibit low-energy deformations that are far too large to be infinitesimally isometric and far too rich to be finitely isometric. Here, rather than abandon the geometric standpoint in favor of a full theory of elastic shells, we introduce the concept of effective isometric deformations defined as deformations that are first-order isometric in a small scale separation parameter given by the ratio of the size of the corrugation to the size of the shell. The main result then states that effective isometries are solutions to a quasilinear second-order PDE whose type is function of an effective geometric Poisson’s ratio. The result is based on a self-adjointness property of the differential operator of infinitesimal isometries; it holds for periodic surfaces that are smooth, piecewise smooth or polyhedral, i.e., periodic surfaces with or without straight and curved creases. In particular, it unifies and generalizes a series of previous results regarding the effective Poisson’s ratio of parallelogram-based origami tessellations. Numerical simulations illustrate and validate the conclusions.

我们认为，将等距变形分为无穷小与有限的标准分类对于柔性壳机构的研究是不够的。事实上，许多柔性壳，特别是周期性波纹的壳，表现出低能量变形，这种变形太大而不能无限等距，也太丰富而不能无限等距。在这里，我们不是为了支持弹性壳的完整理论而放弃几何观点，而是引入有效等距变形的概念，将其定义为由波纹尺寸与壳尺寸之比给出的小尺度分离参数中的一阶等距变形。主要结果表明，有效等距是拟线性二阶偏微分方程的解，其类型是有效几何泊松比的函数。该结果是基于无穷小等距的微分算子的自伴随性质;它适用于光滑、分段光滑或多面体的周期曲面，即具有或不具有直线和弯曲折痕的周期曲面。特别地，它统一和推广了一系列先前关于基于平行四边形的折纸镶嵌的有效泊松比的结果。数值模拟验证了本文的结论。

International Journal of Plasticity

Lithium Concentration and Atomic Chain Bridging Induced Strength–Ductility Synergy in Amorphous Lithiated Sulfur Cathodes

Yuan Gao, Siyi Huang, Xiaoyan Li, Yuli Chen, Bin Ding

doi:10.1016/j.ijplas.2024.103891

锂离子浓度和原子链桥接诱导的非晶锂化硫阴极的强度-延展性协同作用

As an eminent candidate for next-generation cathode materials, sulfur undergoes severe volume changes during electrochemical cycling, resulting in material fractures and performance degradation. Although the electrochemical characteristics of lithiated sulfur have been rigorously studied, their mechanical properties, particularly fracture mechanisms, remain insufficiently understood. To address this gap, we conducted comprehensive atomistic simulations to investigate the fracture behavior of amorphous lithiated sulfur (a-LixS). Our findings reveal that as lithium concentration increases, the fracture mechanism transits from brittle governed by nanoscale cavitation instability to ductile dominated by plastic shear bands launched at the crack tip. This transition is contingent upon local hydrostatic stress exceeding the cavitation strength, elucidated through atomic-level bonding dynamics including rupture, reformation and rotation. At low lithium concentrations, atomic chain bridging posterior to the crack tip is simultaneously identified to enhance crack resistance. The lithiation-induced fracture toughness enhancement is further quantified via domain J-integral analysis. Notably, a unique strength–ductility synergy is identified for a-LixS, attributed to cooperation between lithiation induced heterogeneous bonding environments and atomic chain bridging. This study provides valuable atomic-scale insights into the fracture mechanisms of sulfur cathodes, thereby informing the design of high-energy and durable electrode materials for future applications.

硫作为下一代阴极材料的重要候选者，在电化学循环过程中会发生剧烈的体积变化，导致材料断裂和性能下降。虽然锂化硫的电化学特性已经得到了严格的研究，但它们的力学性能，特别是断裂机制，仍然没有得到充分的了解。为了解决这一空白，我们进行了全面的原子模拟来研究非晶锂化硫(a-LixS)的断裂行为。研究结果表明，随着锂离子浓度的增加，断裂机制由纳米级空化失稳控制的脆性向裂纹尖端发起的塑性剪切带主导的延性转变。这种转变取决于超过空化强度的局部静水应力，这可以通过原子水平的键合动力学(包括破裂、重组和旋转)来解释。在低锂浓度下，裂纹尖端后方的原子链桥接同时被识别，以增强抗裂性。通过区域j积分分析进一步量化了锂化引起的断裂韧性增强。值得注意的是，a- lixs具有独特的强度-延展性协同作用，这归因于锂化诱导的非均相键环境和原子链桥接之间的合作。这项研究为硫阴极的断裂机制提供了有价值的原子尺度的见解，从而为未来应用的高能耐用电极材料的设计提供了信息。

Thin-Walled Structures

A two-step strategy to graft CNTs onto titanium/CFRP interface for interfacial enhancement

Naiyu Jiang, Yingze Li, Nan Zhou, Hongyan Zhang, Xiaohu Zou, Dongxing Zhang

doi:10.1016/j.tws.2024.111629

两步法将CNTs接枝到钛/CFRP界面以增强界面

The primary challenge of fiber metal laminates (FMLs) is the insufficient interfacial adhesion between metal and resin, which impedes the realization of the full potential. To address this issue, a two-step strategy has been proposed: firstly, via the cerium coordination-based approach, followed by grafting carbon nanotubes onto the titanium surface. This modification enhances the interfacial behavior between titanium sheets and polyetheretherketone (PEEK), resulting in increased roughness and wettability on the titanium surface, facilitating tight contact between PEEK and titanium sheets while reducing defects at the interface. Compared to CF/PEEK-sandblasted Ti, the modified CF/PEEK-Ti composites exhibit significantly enhanced interfacial shear strength, equivalent flexural strength, and interlaminate shear strength with an increase of 205.4% (39.4 MPa), 133.3% (1434.3 MPa) and 95.2% (93.7 MPa), respectively. Additionally, the failure mode has shifted from interfacial failure to cohesive failure. The interface enhancement mechanism can be attributed to the synergistic effects of coordination bonding, mechanical interlocking, and multiple interactions. This facile two-step modification method demonstrates the potential to enhance the interfacial properties of CF/PEEK-Ti composites.

金属纤维层压板(FMLs)的主要挑战是金属与树脂之间的界面附着力不足，这阻碍了其充分发挥潜力。为了解决这一问题，提出了两步策略:首先，通过基于铈配位的方法，然后将碳纳米管接枝到钛表面。这种改性增强了钛片与聚醚醚酮(PEEK)之间的界面行为，从而增加了钛表面的粗糙度和润湿性，促进了PEEK与钛片之间的紧密接触，同时减少了界面上的缺陷。与CF/ peek -喷砂Ti相比，改性后的CF/PEEK-Ti复合材料的界面抗剪强度、等效抗折强度和层间抗剪强度分别提高了205.4% (39.4 MPa)、133.3% (1434.3 MPa)和95.2% (93.7 MPa)。此外，破坏模式已经从界面破坏转变为内聚破坏。界面增强机制可归因于配位键、机械联锁和多重相互作用的协同作用。这种简单的两步改性方法显示了增强CF/PEEK-Ti复合材料界面性能的潜力。

Extended GBT Formulation for Eigenvalue Buckling Analyses of Thin-Walled Members with Edge-Stiffened Holes

Liping Duan, Ji Miao, Hai-Ting Li, Jincheng Zhao

doi:10.1016/j.tws.2024.111628

边缘加筋孔薄壁构件屈曲特征值分析的扩展GBT公式

Cold-formed steel sections with edge-stiffened holes exhibit increasing popularity in the building industry. This paper extends the generalized beam theory (GBT) to the scope of handling this kind of members so that modal decomposition of the coupled buckling modes of these members into the set of pure buckling modes can be realized, which is essential for a direct strength method (DSM)-based design. The presented GBT formulation is built upon the XGBT approach that was previously proposed by the authors [1,2,3] for handling the un-stiffened perforated steel profiles, but its novelty lies in the scheme used to connect the previous approach to the MITC4 shell FEs. Specifically, the previous GBT-based beam FEs are employed to handle the perforated member but without stiffeners, and the MITC4 shell FEs are used to model the stiffeners along the hole edges; further, the mortar method-based interface elements are employed to weakly ensure the compatibility between the shell and the GBT-based FEs no matter how mismatched their meshes are. Some illustrative examples are presented to show the potential of the proposed approach, where linear buckling analysis results for the members with circular holes obtained by the present GBT are compared with those obtained by the ANSYS shell FE analyses. The presented approach shows advantages in computational costs and interpretability of the obtained results over the shell model.

冷弯型钢边加筋孔在建筑工业中越来越受欢迎。本文将广义梁理论(GBT)推广到处理这类构件的范围，实现了将这类构件的耦合屈曲模态分解为纯屈曲模态集合，这是基于直接强度法(DSM)的设计所必需的。所提出的GBT配方是建立在作者先前提出的用于处理未加筋穿孔钢型材的XGBT方法的基础上的[1,2,3]，但其新颖之处在于用于将先前方法连接到MITC4壳FEs的方案。具体而言，采用先前的基于gbt的梁有限元模型来处理穿孔构件但不含加强筋，而使用MITC4壳有限元模型来模拟沿孔边缘的加强筋;此外，采用基于迫击炮法的界面单元弱保证弹体与基于gbt法的弹体之间的兼容性，无论两者的网格匹配程度如何不匹配。通过与ANSYS壳体有限元分析结果的比较，说明了该方法的可行性。与壳模型相比，该方法在计算成本和所得结果的可解释性方面具有优势。

来源：复合材料力学仿真Composites FEM

【新文速递】2024年1月27日复合材料SCI期刊最新文章

今日更新：Composites Part A: Applied Science and Manufacturing 1 篇，Composites Science and Technology 1 篇Composites Part A: Applied Science and ManufacturingImproving carbon fibre reinforced polyphenylene sulfide using amine and phenolic interphase modificationsSameh Dabees, Ameya Borkar, Ben Newman, Žan Simon, David J. Hayne, Peirs Coia, Luke C. Hendersondoi:10.1016/j.compositesa.2024.108045用胺和酚类间相改性改进碳纤维增强聚苯硫醚In this study, a straightforward in-situ surface modification procedure was used to enhance the interfacial adhesion of carbon fibre (CF)-reinforced polyphenylene sulfide (PPS). To do this, 4-nitroaniline and 4-aminophenol were grafted to the surface of carbon fibres. The goal was to capitalise on the hydrogen bonding capability of the grafted molecules with the exposed sulphur groups present in the polymer backbone of PPS. This modification has resulted in a notable enhancement in both the tensile and flexural strength of the PPS/CF composite, with an increase of 12.3% and 19.3%, respectively. Moreover, tensile, and flexural modulus has been increased by 15% and 16%, respectively. Scanning electron microscopy (SEM) examinations confirm that the treated CF contributes to the facilitation of a more homogeneous stress distribution throughout the matrix. This serves to alleviate stress concentrations that may arise at certain spots, reducing the probability of premature failure or crack formation. Counterintuitively, the amino grafted fibres outperformed the phenolic enriched fibres, despite the amine having a lower potential for hydrogen bonding. We propose that the sulphur atom within the PPS polymer presents an opportunity for hydrogen bonding but also a currently underutilised interaction, σ*-bonding, that could be capitalised on to enhance thermoplastic composite performance. Furthermore, the achievement of effectively preparing a modified CF surface offers valuable insights into the development of high-performance thermoplastic composites using easily accessible materials via a straightforward method.在这项研究中，采用了一种简单的原位表面改性方法来增强碳纤维(CF)增强聚苯硫醚(PPS)的界面附着力。为此，4-硝基苯胺和4-氨基酚被接枝到碳纤维表面。目的是利用接枝分子的氢键能力，暴露硫基团存在于PPS的聚合物主链中。改性后的PPS/CF复合材料的拉伸强度和弯曲强度均显著提高，分别提高了12.3%和19.3%。此外，拉伸模量和弯曲模量分别提高了15%和16%。扫描电镜(SEM)检查证实，经过处理的CF有助于促进整个基质中更均匀的应力分布。这有助于减轻在某些点可能出现的应力集中，减少过早失效或裂纹形成的可能性。与直觉相反，氨基接枝纤维的性能优于酚类纤维，尽管胺具有较低的氢键电位。我们提出，PPS聚合物中的硫原子为氢键提供了机会，但也为目前未充分利用的相互作用σ*键提供了机会，这可以用来提高热塑性复合材料的性能。此外，有效制备改性CF表面的成就为通过简单的方法使用易于获取的材料开发高性能热塑性复合材料提供了有价值的见解。Composites Science and TechnologyElectrical and thermal behaviour of Z-pin reinforced carbon-fibre composite laminates under fault currentsMudan Chen, Zhaobo Zhang, Bing Zhang, Giuliano Allegri, Xibo Yuan, Stephen R. Hallettdoi:10.1016/j.compscitech.2024.110466 z针增强碳纤维复合材料层合板在故障电流下的电学和热行为Carbon-fibre reinforced polymer (CFRP) composites typically have poor electrical conductivity, primarily due to the conductive carbon fibres being separated by the insulating polymer matrix material. This is even more so in the case of interlayer toughened material systems that have an increased interlaminar spacing between the conductive carbon fibre layers. To mitigate the poor electrical conductivity of CFRP composites, the behaviour of Z-pinned laminates under electrical current was here studied experimentally. The in-plane and through-thickness fault currents were investigated for a quasi-isotropic (QI) composite laminate made from M21/IMA prepreg. Two kinds of pin materials (T300/BMI composite and copper) were used at two different volume fractions (0.1 % and 0.25 %). The pins reduced the through-thickness current resistance by two orders of magnitude, with a much smaller data variation, and up to one order for the in-plane direction. Through the use of electrically insulated pins, it was found that the electrical conductivity enhancement is caused by the fibre crimping around the pin and is unrelated to the pin material. Z-pins decreased the temperature increment caused by Joule heating during fault currents, thereby ensuring structural safety.碳纤维增强聚合物(CFRP)复合材料通常具有较差的导电性，主要是由于导电碳纤维被绝缘聚合物基体材料隔开。在导电碳纤维层之间的层间间距增加的层间增韧材料系统中更是如此。为了缓解CFRP复合材料导电性差的问题，对z -钉压层合板在电流作用下的性能进行了实验研究。研究了M21/IMA预浸料制备的准各向同性(QI)复合层压板的面内和通层故障电流。采用两种不同体积分数(0.1 %和0.25 %)的引脚材料(T300/BMI复合材料和铜)。引脚将通厚电流电阻降低了两个数量级，数据变化小得多，而平面内方向的电流电阻则降低了一个数量级。通过使用电绝缘引脚，发现导电性的增强是由引脚周围的纤维卷曲引起的，与引脚材料无关。z引脚减小了故障电流时焦耳加热引起的温升，保证了结构的安全。来源：复合材料力学仿真Composites FEM