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【新文速递】2024年2月15日复合材料SCI期刊最新文章

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今日更新:Composite Structures 1 篇,Composites Part A: Applied Science and Manufacturing 2 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 4 篇

Composite Structures

Adjustable mechanical performances of 4D-printed shape memory lattice structures

Yu Dong, Kaijuan Chen, Hu Liu, Jian Li, Zhihong Liang, Qianhua Kan

doi:10.1016/j.compstruct.2024.117971

4D 打印形状记忆晶格结构的可调机械性能

Lattice structures are widely used due to their inherent advantages. With the development of smart devices, there is a growing demand for programmable, adjustable, and reconfigurable performances. However, a significant limitation of traditional lattice structures is that their shape, function, and performance cannot be changed after fabrication. In order to address this issue, we conducted experimental and simulated investigations on the shape memory effect, adjustable mechanical performances, and their deformation mechanism using the shape memory programming method. Two bending-dominated lattice structures, namely four curved bars lattice structure (FCBL) and sinusoidal wave horseshoe lattice structure (SWHL), were taken as examples. Results show that the deformation modes of both structures are switched from a bending-dominated mode to a stretching-dominated one after programming while exhibiting distinct bending sections. FCBL displays a 'C' shape with one bending section, whereas SWHL exhibits an 'S' shape with two bending sections. These deformation modes significantly enhance the tensile moduli by 480.9% (FCBL) and 1546% (SWHL), and change their Poisson’s ratio from -0.29 to 0.25 (FCBL) and -0.31 to 0.43 (SWHL), respectively. The modulus and Poisson’s ratio of FCBL and SWHL are well reproduced by the finite element modeling, providing a reference for designing the tunable mechanical performances of lattice structures.

晶格结构因其固有的优势而得到广泛应用。随着智能设备的发展,人们对可编程、可调节和可重构性能的需求日益增长。然而,传统晶格结构的一个显著局限是其形状、功能和性能在制造后无法改变。为了解决这个问题,我们利用形状记忆编程方法对形状记忆效应、可调机械性能及其变形机制进行了实验和模拟研究。我们以两种以弯曲为主的晶格结构(即四弯杆晶格结构(FCBL)和正弦波马蹄形晶格结构(SWHL))为例进行了研究。结果表明,这两种结构的变形模式在编程后都从以弯曲为主的模式转换为以拉伸为主的模式,同时表现出明显的弯曲截面。FCBL 显示出具有一个弯曲截面的 "C "形,而 SWHL 则显示出具有两个弯曲截面的 "S "形。这些变形模式分别将拉伸模量大幅提高了 480.9%(FCBL)和 1546%(SWHL),并将泊松比从 -0.29 变为 0.25(FCBL)和 -0.31 变为 0.43(SWHL)。有限元建模很好地再现了 FCBL 和 SWHL 的模量和泊松比,为设计晶格结构的可调力学性能提供了参考。


Composites Part A: Applied Science and Manufacturing

Carbon fibre surface modification by plasma for enhanced polymeric composite performance: A review

Maximilian Pitto, Holger Fiedler, Nam Kyeun Kim, Casparus Johannes Reinhard Verbeek, Tom David Allen, Simon Bickerton

doi:10.1016/j.compositesa.2024.108087

利用等离子体对碳纤维表面进行改性,以提高聚合物复合材料的性能:综述

Energetic species in plasma have been used for four decades to functionalise or coat the hydrophobic and inert carbon fibre (CF) surface with the aim to enhance interface performance with polymeric matrices. To encourage a data-driven polymeric composite manufacturing process, this review communicates introductory plasma science, treatment methods, reaction mechanisms, fibre properties and composite performance. The digest on fibre properties after plasma modification informs the mechanical property enhancement of micro- and macro-scale fibre-reinforced polymeric composites. To reliably emulate CF plasma treatments for industrial polymeric composites manufacture, the bulk plasma must be characterised to produce the same reactive species in a non-identical plasma device. Integration of plasma diagnostics can spearhead interdisciplinary work to predict CF surface modification throughout the bundle and fabric, substituting the trial and error status quo. To justify the use of plasma, its environmental, social, and economic impact must be quantitatively compared to alternative fibre surface treatments.

四十年来,等离子体中的高能物质一直被用来对疏水性和惰性碳纤维(CF)表面进行功能化或涂层处理,以提高其与聚合物基质的界面性能。为了鼓励以数据为导向的聚合物复合材料制造工艺,本综述介绍了等离子体科学、处理方法、反应机制、纤维特性和复合材料性能。等离子体改性后的纤维性能摘要为微观和宏观尺度纤维增强聚合物复合材料机械性能的提高提供了信息。要在工业聚合物复合材料制造中可靠地模拟 CF 等离子处理,必须对大块等离子体进行表征,以便在非相同的等离子体设备中产生相同的反应物种。整合等离子体诊断技术可以引领跨学科工作,预测整个纤维束和纤维织物的 CF 表面改性,从而取代反复试验的现状。为了证明使用等离子体的合理性,必须将其对环境、社会和经济的影响与其他纤维表面处理方法进行量化比较。


A lightweight, flexible, and polarization-insensitive microwave absorbing honeycomb core using conductive losses in printed periodic pattern

Sang Min, Won Jun Lee

doi:10.1016/j.compositesa.2024.108089

一种轻质、灵活、对偏振不敏感的微波吸收蜂窝芯,采用印刷周期图案中的导电损耗

This study proposes a method for providing electromagnetic function by arranging patterns three-dimensionally on honeycomb partition walls. A conductive paste is thinly printed to fabricate a resistance component. To increase the current path induced by the incident electromagnetic waves, a rectangular pattern with an aspect ratio is used to further generate electromagnetic losses. Rectangular patterns are arranged alternately to ensure the homogeneity of the entire honeycomb medium. The proposed honeycomb achieved excellent absorption performance in the C, X, and Ku bands, regardless of the polarization. Simulations were used to show that the microwave-absorption performance of a honeycomb with a three-dimensional pattern could be estimated analytically. The obtained results were compared with those of other studies. The proposed honeycomb was effective in reducing the broadband monostatic radar cross section when applied to the leading edge of a wing box.

本研究提出了一种通过在蜂窝隔墙上三维排列图案来提供电磁功能的方法。通过薄薄地印刷导电浆料来制造电阻元件。为了增加入射电磁波引起的电流路径,使用了具有高宽比的矩形图案,以进一步产生电磁损耗。矩形图案交替排列,以确保整个蜂窝介质的均匀性。所提出的蜂窝在 C、X 和 Ku 波段都实现了出色的吸收性能,与偏振无关。模拟结果表明,具有三维图案的蜂窝的微波吸收性能可以通过分析估算出来。所得结果与其他研究结果进行了比较。当应用于翼盒前缘时,所提出的蜂窝能有效减少宽带单静态雷达截面。


Composites Part B: Engineering

Calcium crosslinked macroporous bacterial cellulose scaffolds with enhanced in situ mineralization and osteoinductivity for cranial bone regeneration

Xiaowei Xun, Yaqiang Li, Ming Ni, Yong Xu, Jiaxin Li, Dongxue Zhang, Guochang Chen, Haiyong Ao, Honglin Luo, Yizao Wan, Tao Yu

doi:10.1016/j.compositesb.2024.111277

用于颅骨再生的钙交联大孔细菌纤维素支架具有更强的原位矿化和骨诱导能力

The inherent biological inertness and lack of three-dimensional (3D) macroporous structures greatly hinder the use of pristine bacterial cellulose (BC) as a tissue engineering scaffold for bone regeneration. To address this issue, we developed a simple and effective strategy to fabricate a BC-based scaffold with excellent bioactivity and macroporous structure by crosslinking short-cut BC nanofibers using Ca2+. The Ca2+ crosslinked macroporous BC scaffold (MPBC@Ca) presents better structural stability due to the enhanced cellulose hydration. Importantly, the Ca2+ on the surface of BC nanofibers can serve as an active nucleation site to accelerate the deposition of hydroxyapatite (HAp), which is beneficial for the construction of biomimetic bone tissue extracellular matrix (ECM) microenvironment. The HAp-deposited MPBC@Ca scaffolds (HAp-MPBC@Ca) with biomimetic ECM microenvironment have excellent cytocompatibility and enhanced osteogenic differentiation of stem cells in vitro. Furthermore, the results of in vivo tests revealed that the biomimetic ECM microenvironment HAp-MPBC@Ca scaffold has favorable osteoinductivity and accelerates cranial bone tissue regeneration. This study proposes a novel strategy to improve the bioactivity of BC and presents the great potential of biomimetic ECM microenvironment BC-based scaffold for repairing large cranial bone defects.

原始细菌纤维素(BC)固有的生物惰性和缺乏三维(3D)大孔结构极大地阻碍了其作为组织工程支架用于骨再生。为解决这一问题,我们开发了一种简单有效的策略,通过使用 Ca2+ 交联短切 BC 纳米纤维,制造出一种具有优异生物活性和大孔结构的 BC 基支架。由于纤维素水合作用增强,Ca2+交联的大孔BC支架(MPBC@Ca)具有更好的结构稳定性。重要的是,BC 纳米纤维表面的 Ca2+ 可作为活性成核位点,加速羟基磷灰石(HAp)的沉积,有利于构建仿生骨组织细胞外基质(ECM)微环境。具有仿生 ECM 微环境的 HAp 沉积 MPBC@Ca 支架(HAp-MPBC@Ca)具有良好的细胞相容性,并能增强体外干细胞的成骨分化。此外,体内试验结果表明,仿生 ECM 微环境 HAp-MPBC@Ca 支架具有良好的骨诱导性,可加速颅骨组织再生。该研究提出了一种提高 BC 生物活性的新策略,并展示了基于生物仿生 ECM 微环境 BC 支架修复大面积颅骨缺损的巨大潜力。


Composites Science and Technology

Mathematical study of the mechanical properties of NOL rings with different winding process parameters

Zesheng Huang, Wei Shen, Lifeng Chen, Lvtao Zhu

doi:10.1016/j.compscitech.2024.110502

 

不同缠绕工艺参数下 NOL 环机械性能的数学研究

This study investigates the impact of different winding tension parameters (40 N, 45 N, and 50 N) on the quality of fiber-wrapped products using the Navy Ordnance Laboratory (NOL) composite rings. Design Expert software was utilized to analyze the response surface of fiber winding process parameters, including winding tension, winding speed, and curing temperature, which significantly influence the mechanical properties of the fiber. Mathematical models were developed to understand the combined effects of these process parameters on the mechanical properties of NOL rings. Furthermore, a satisfaction function was employed to synthesize the two mechanical response variables into a comprehensive index for parameter optimization. Experimental validation was conducted to verify the reliability of the proposed design scheme.

本研究使用海军军械实验室(NOL)的复合环,研究了不同缠绕张力参数(40 N、45 N 和 50 N)对纤维缠绕产品质量的影响。利用 Design Expert 软件分析了纤维缠绕工艺参数的响应面,包括缠绕张力、缠绕速度和固化温度,这些参数对纤维的机械性能有显著影响。通过建立数学模型,了解了这些工艺参数对 NOL 环机械性能的综合影响。此外,还采用了满意度函数,将两个机械响应变量综合成一个综合指标,用于参数优化。通过实验验证了所提设计方案的可靠性。


Waste cotton stalks enhancing the impact and crystallization performances of polylactic acid/polypropylene composite with PP-g-mah compatibilizer

Jin Shang, Abdukaiyum Abdurexit, Ruxangul Jamal, Tursun Abdiryim, Xiong Liu, Fangfei Liu, Zhiwei Li, Yanqiang Zhou, Jin Wei, Xinsheng Tang

doi:10.1016/j.compscitech.2024.110485

 

废棉秆与 PP-g-mah 相容剂可提高聚乳酸/聚丙烯复合材料的抗冲击和结晶性能

Although polymers based on polylactic acid (PLA) are considered by researchers as prime candidates for replacing traditional plastics, they are confronted with challenges including high production costs, limited thermal stability, and inferior impact resistance. In this study, novel composites with exceptional impact resistance, robust thermal stability, and satisfactory crystalline properties were fabricated by using PLA and polypropylene (PP) as raw materials, PP-g-MAH was employed as a compatibilizer to enhance the compatibility between the individual components. by adjusting the quantity of discarded cotton stalk fibers (CSF). The optimal mass ratio of CSF was determined to be 20%, resulting in a composite that exhibited a moderate increase of 56.31% in impact strength and a remarkable improvement of 23.05% in Vicat softening temperature. While the crystallinity was enhanced and the crystallization temperature (Tc) value decreased, the storage modulus also increased. Furthermore, the observed increase in storage modulus within the temperature range of 80 °C–100 °C was attributed to the influence of polymer cold crystallization. The hydrophobicity of the composite was enhanced. Significantly, this strategy can be extended to the application of other plant fibers, improving the crystalline properties of semi-crystalline polymers such as PLA and exemplifying the true ‘valorization of waste' through the secondary utilization of discarded CSF.

尽管以聚乳酸(PLA)为基础的聚合物被研究人员视为替代传统塑料的主要候选材料,但它们也面临着生产成本高、热稳定性有限和抗冲击性差等挑战。本研究以聚乳酸(PLA)和聚丙烯(PP)为原料,采用 PP-g-MAH 作为相容剂,通过调整废弃棉秆纤维(CSF)的用量,制备出具有优异抗冲击性、强大热稳定性和令人满意的结晶特性的新型复合材料。最终确定 CSF 的最佳质量比为 20%,使复合材料的冲击强度提高了 56.31%,维卡软化温度显著提高了 23.05%。在提高结晶度和降低结晶温度 (Tc) 值的同时,还提高了储存模量。此外,在 80 °C-100 °C 的温度范围内观察到的储存模量增加是由于聚合物冷结晶的影响。复合材料的疏水性得到了增强。值得注意的是,这一策略可扩展到其他植物纤维的应用,改善半结晶聚合物(如聚乳酸)的结晶特性,并通过对废弃 CSF 的二次利用体现真正的 "废物利用"。


Flexible bandwidth-enhanced metamaterial absorbers with epoxy/graphene nanoplatelets-silver nanowire polymer composites as substrates

M. Anjali, Raghunath Sahoo, Lincy Stephen, C.V. Krishnamurthy, V. Subramanian

doi:10.1016/j.compscitech.2024.110492

 

以环氧树脂/石墨烯纳米片-银纳米线聚合物复合材料为基材的柔性带宽增强超材料吸收器

The realm of flexible devices has seen considerable advancement in recent technology due to their ability to bend and conform to particular shapes. Flexible metamaterial absorbers offer the advantage of combining the features of conventional metamaterials with the attributes of conformal systems, thereby opening new avenues in electromagnetic technology. This work involves the realization of flexible metamaterial absorbers with epoxy/graphene nanoplatelets-silver nanowire (GnP-AgNW) polymer composites as substrates; with a bandwidth enhancement achieved by incorporating losses in the substrate and combining resonances in the unit cell. A novel in-situ technique is employed to synthesize the nanohybrid GnP-AgNW (GA) with different weight percentages of AgNWs grown on GnP (GAx; x = 10, 15, 20 wt%). The dielectric measurements of the polymers showed that an increase in weight percentages of AgNWs in the composite enhanced the dielectric constant as well as losses of the polymer (εr՛: 7.7 to 8.8 and εr՛՛: 0.62 to 1.12). The numerical study on the designed flexible metamaterial absorbers with these substrates of thickness 1.4 mm showed a maximum absorptivity of 99% with a bandwidth (having absorption >90%) varying between 1.2 and 1.86 GHz. The experimental measurements on the fabricated metamaterial absorber were found to match the simulation results closely. The polymer composites demonstrated in this work are attractive candidates as substrates for metamaterial absorbers for conformal applications. This paper approaches the problem of bandwidth enhancement of metamaterial absorbers by material engineering along with the resonant structure optimization leading to a synergetic effect in the properties of absorber.

柔性器件能够弯曲并符合特定形状,因此在最近的技术领域取得了长足的进步。柔性超材料吸波材料具有将传统超材料的特性与保形系统的属性相结合的优势,从而为电磁技术开辟了新的道路。这项研究以环氧树脂/石墨烯纳米片-银纳米线(GnP-AgNW)聚合物复合材料为基材,实现了柔性超材料吸波材料;通过在基材中加入损耗和在单元格中结合共振实现了带宽增强。我们采用了一种新颖的原位技术来合成纳米杂化 GnP-AgNW(GA),在 GnP 上生长不同重量百分比的 AgNW(GAx;x = 10、15、20 wt%)。聚合物的介电测量结果表明,复合材料中 AgNWs 重量百分比的增加提高了聚合物的介电常数和损耗(εr՛:7.7 至 8.8;εr՛՛:0.62 至 1.12)。对使用这些厚度为 1.4 毫米的基底设计的柔性超材料吸波材料进行的数值研究表明,其最大吸收率为 99%,带宽(吸收率大于 90%)在 1.2 至 1.86 千兆赫之间。对制作的超材料吸收器的实验测量结果与模拟结果非常吻合。这项工作中展示的聚合物复合材料是具有吸引力的超材料吸收器基材,可用于保形应用。本文通过材料工程和谐振结构优化来解决超材料吸收器的带宽增强问题,从而在吸收器的性能方面产生协同效应。


Trans-scale analysis of 3D braided composites with voids based on micro-CT imaging and unsupervised machine learning

Xinyi Song, Jin Zhou, Di Zhang, Shenghao Zhang, Pei Li, Longteng Bai, Xiaohui Yang, Feiping Du, Xuefeng Chen, Zhongwei Guan, Wesley J. Cantwell

doi:10.1016/j.compscitech.2024.110494

 

基于显微 CT 成像和无监督机器学习的空隙三维编织复合材料跨尺度分析

Voids are unavoidable during the manufacturing of 3D braided composites. This study proposes an unsupervised machine learning method combined with micro-computed tomography (micro-CT) scanning and a progressive damage analysis to analyze defects in these composites at a trans-scale level. The method enables the creation of real multiscale models and the determination of the porosity in both the intra-yarn (1.52 %) and inter-yarn (5.04 %) planes. Here, the unsupervised machine learning method is introduced in a trans-scale damage analysis to reduce calculation dimensions and to visualize the clustering data. A user-defined material subroutine (UMAT) is also developed to implement the trans-scale damage model. The experimental validation of the simulation results demonstrates the effective trans-scale damage analysis, showing the predominant pull-shear damage in the yarns, which is primarily located at the interfaces both between the yarns and between the yarns and the matrix. Finally, based on the scanned geometric data the degradation in modulus and strength of 3D braided composites with porosity is studied.

在三维编织复合材料的制造过程中,空洞是不可避免的。本研究提出了一种无监督机器学习方法,结合微型计算机断层扫描(micro-CT)和渐进式损伤分析,在跨尺度水平上分析这些复合材料中的缺陷。该方法可创建真实的多尺度模型,并确定纱内(1.52%)和纱间(5.04%)平面的孔隙率。在此,我们在跨尺度损伤分析中引入了无监督机器学习方法,以减少计算维数并实现聚类数据的可视化。此外,还开发了用户自定义材料子程序(UMAT)来实现跨尺度损伤模型。模拟结果的实验验证证明了跨尺度损伤分析的有效性,显示了纱线中主要的拉剪损伤,这种损伤主要位于纱线之间以及纱线与基体之间的界面。最后,根据扫描的几何数据,研究了带有孔隙率的三维编织复合材料的模量和强度退化情况。



来源:复合材料力学仿真Composites FEM
ACTMechanicalSystemMAGNETDeform复合材料ECAD参数优化材料多尺度仿生试验
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首次发布时间:2024-11-06
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【新文速递】2024年2月19日固体力学SCI期刊最新文章

今日更新:Journal of the Mechanics and Physics of Solids 2 篇,Mechanics of Materials 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 1 篇Journal of the Mechanics and Physics of SolidsA reactive electrochemomechanical theory for growth and remodeling of polyelectrolyte hydrogels and application to dynamic polymerization of DNA hydrogelsBrandon K. Zimmerman, Bibekananda Datta, Ruohong Shi, Rebecca Schulman, Thao D. Nguyendoi:10.1016/j.jmps.2024.105568聚电解质水凝胶生长和重塑的反应电化学机械理论及其在 DNA 水凝胶动态聚合中的应用This study develops a framework for growth and remodeling of active polyelectrolyte hydrogels that accounts for effects of compositional changes on the mechanical response. By developing a reactive electrochemomechanical theory, thermodynamical constraints upon reactive and remodeling processes are elucidated within a general framework that allows any number of chemical reactions to evolve the response of the gel and transfer mass and charge between constituents. Fully coupled, nonlinear constitutive relations are adopted for molar fluxes, allowing exploration of effects including cross-diffusion, electrophoresis, and electro-osmosis. A robust finite element implementation is developed in the open source FEBio software (febio.org) by exploiting an equivalence between electrochemomechanics and mixture theory. The implementation is verified against analytical solutions for free swelling, and a proper reduction to a prior chemomechanical theory is demonstrated for neutral gels swollen only by a solvent with no solutes. The theory and implementation are then applied to model the tunable large swelling achieved through dynamic polymerization of DNA crosslinkers seen in our recently developed experimental hydrogel system (Cangialosi et al., 2017). A novel constitutive model for reaction-driven evolution of the locking stretch λL in a non-Gaussian mechanical free energy was developed, where the increasing concentration of DNA crosslinkers makes further swelling energetically favorable. With a single free parameter, excellent agreement was found between measured and predicted equilibrium swelling ratios. This study demonstrated the ability to extend the electrochemomechanical framework to include chemical reactions and composition-aware constitutive models, and showed that development of reactive models allows simulation of complex dynamic polymerization phenomena not treated before. The theoretical frame here can be further expanded in scope to incorporate additional non-ideal and nonlinear phenomena.本研究为活性聚电解质水凝胶的生长和重塑建立了一个框架,该框架考虑了成分变化对机械响应的影响。通过发展反应电化学机械理论,在一个允许任何数量的化学反应来改变凝胶反应并在成分间传递质量和电荷的通用框架内,阐明了反应和重塑过程的热力学约束。摩尔通量采用完全耦合的非线性构成关系,允许探索包括交叉扩散、电泳和电渗在内的效应。利用电化学力学和混合物理论之间的等效性,在开源 FEBio 软件(febio.org)中开发了稳健的有限元实现方法。该实现方法与自由溶胀的分析解决方案进行了验证,并证明了对于仅由无溶剂的溶剂溶胀的中性凝胶,可以适当还原为先前的化学机械理论。然后将该理论和实现方法应用于模拟我们最近开发的实验水凝胶系统(Cangialosi 等人,2017 年)中通过 DNA 交联剂的动态聚合实现的可调大溶胀。针对非高斯机械自由能中锁定拉伸 λL 的反应驱动演化建立了一个新的构成模型,在该模型中,DNA 交联剂浓度的增加使进一步溶胀在能量上变得有利。只需一个自由参数,就能发现测量值与预测值之间的平衡溶胀率非常一致。这项研究证明了将电化学机械框架扩展到包括化学反应和成分感知构成模型的能力,并表明开发反应模型可以模拟以前未处理过的复杂动态聚合现象。这里的理论框架还可以进一步扩展,纳入更多的非理想和非线性现象。Prediction of yield surface of single crystal copper from discrete dislocation dynamics and geometric learningWu-Rong Jian, Mian Xiao, WaiChing Sun, Wei Caidoi:10.1016/j.jmps.2024.105577从离散位错动力学和几何学习预测单晶铜的屈服面The yield surface of a material is a criterion at which macroscopic plastic deformation begins. For crystalline solids, plastic deformation occurs through the motion of dislocations, which can be captured by discrete dislocation dynamics (DDD) simulations. In this paper, we predict the yield surfaces and strain-hardening behaviors using DDD simulations and a geometric manifold learning approach. The yield surfaces in the three-dimensional space of plane stress are constructed for single-crystal copper subjected to uniaxial loading along the [100] and [110] directions, respectively. With increasing plastic deformation under [100] loading, the yield surface expands nearly uniformly in all directions, corresponding to isotropic hardening. In contrast, under [110] loading, latent hardening is observed, where the yield surface remains nearly unchanged in the orientations in the vicinity of the loading direction itself but expands in other directions, resulting in an asymmetric shape. This difference in hardening behaviors is attributed to the different dislocation multiplication behaviors on various slip systems under the two loading conditions.材料的屈服面是宏观塑性变形开始的标准。对于晶体固体,塑性变形是通过位错运动发生的,而位错运动可以通过离散位错动力学(DDD)模拟捕捉到。本文利用 DDD 模拟和几何流形学习方法预测屈服面和应变硬化行为。我们为分别沿 [100] 和 [110] 方向承受单轴载荷的单晶铜构建了平面应力三维空间中的屈服面。在[100]方向加载时,随着塑性变形的增加,屈服面几乎在所有方向上均匀扩展,相当于各向同性硬化。相反,在[110]加载条件下,则出现了潜伏硬化,屈服面在加载方向附近的方向上几乎保持不变,但在其他方向上却扩大了,从而形成了不对称的形状。硬化行为的这种差异归因于两种加载条件下不同滑移系统上不同的位错倍增行为。Mechanics of MaterialsMechanical properties and deformation mechanisms of single crystal Mg micropillars subjected to high-strain-rate C-axis compressionZ. Lin, D.J. Magagnosc, J. Wen, X. Hu, H.D. Espinosadoi:10.1016/j.mechmat.2024.104951单晶镁微柱在高应变速率 C 轴压缩条件下的力学性能和变形机制The mechanical properties and deformation mechanisms of single crystal magnesium under c-axis quasi-static and high-strain rate compressions are investigated through in situ scanning electron microscope (SEM) experiments and post-mortem transmission electron microscope (TEM) characterization. The findings revealed that ductility and high rates of hardening are preserved for pillars as large as 15 μm. Furthermore, rate effects result in a mild increase in flow stress with plastic deformations controlled primarily by the slip of <a+c> type dislocations. Importantly and in contrast to other literature reports, plastic deformation occurs in the absence of twining. As the strain increases and plastic deformation exceeds about 4%, crystal rotation activates basal slip, type dislocations, resulting in a more rate independent flow stress. TEM observation on micropillars compressed at a strain rate of 250/s, revealed the activation of {11 2¯2¯} <1¯1¯23> slip systems and high mobility of screw dislocations as major contributors to plastic strains in excess of 10% without fracture. These findings are relevant to the design of lightweight materials used in transportation systems, e.g., selection of material grain size. Moreover, the experimental data here reported provides the materials science community with a unique opportunity to validate discrete dislocation dynamics (DDD) formulations employed in multiscale design of materials.通过原位扫描电子显微镜(SEM)实验和死后透射电子显微镜(TEM)表征,研究了单晶镁在 c 轴准静态和高应变率压缩条件下的机械性能和变形机制。研究结果表明,大至 15 μm 的柱体仍保持了延展性和高硬化率。此外,速率效应导致流动应力轻度增加,塑性变形主要由 <a+c> 型位错滑移控制。重要的是,与其他文献报道不同,塑性变形是在没有缠绕的情况下发生的。随着应变的增加和塑性变形超过约 4%,晶体旋转激活了基底滑移和 型位错,从而产生了与速率更不相关的流动应力。对以 250/s 应变速率压缩的微柱体进行的 TEM 观察显示,基底滑移和 型位错的激活与应变速率无关。{11 2¯2¯} <1¯1¯23> 滑移系统和螺钉位错的高流动性是导致塑性应变超过 10%而不断裂的主要原因。这些发现与运输系统中使用的轻质材料的设计有关,例如材料晶粒大小的选择。此外,本文报告的实验数据为材料科学界提供了一个独特的机会,以验证多尺度材料设计中采用的离散位错动力学(DDD)公式。International Journal of PlasticityModelling and simulation of dynamic compression of Bulk Metallic Glasses at room and elevated temperatures using split Hopkinson pressure bar setupArun Kamble, Parag Tandaiyadoi:10.1016/j.ijplas.2024.103915使用分体式霍普金森压力棒装置对散装金属玻璃在室温和高温下的动态压缩进行建模和模拟This paper presents a modelling and simulation study of dynamic compression behaviour of Bulk Metallic Glasses (BMGs) at room and elevated temperatures using the split Hopkinson pressure bar (SHPB) setup. The primary objective of this study is to develop and validate a constitutive model and simulation methodology capable of predicting the high strain rate response of BMGs at different temperatures. We propose a constitutive model for BMGs that accounts for the effects of high strain rates and elevated temperatures. We numerically implemented this model in ABAQUS/Explicit Finite Element Analysis software by writing a Vectorized User Material (VUMAT) subroutine. The methodology for modelling and simulation of dynamic compression of BMG specimens using the SHPB setup is developed. The present simulations are able to correctly predict the rate-independent response of Zr41.2Ti13.8Cu12.5 Ni10Be22.5 (Vitreloy-1) BMG under dynamic compression at room and elevated temperatures. Furthermore, the present simulations are also able to correctly predict the negative strain rate sensitivity (SRS) of Zr52.5Cu17.9Ni14.6Al10Ti5 (Vitreloy-105) BMG at room temperature. Finally, the present simulations correctly predict that the failure stress of Zr64.13Cu15.75Ni10.12Al10 BMG decreases with increasing temperature and exhibits a minimal positive SRS. The present study is the first successful attempt to model the mechanical response of various BMGs under dynamic compression and at room and elevated temperatures. In particular, the experimentally observed negative SRS in some BMGs has been successfully simulated. The present work has important implications for the design of next generation spacecraft shields that are based on BMGs for mitigating the effects of hypervelocity impacts from debris in space.本文介绍了利用分体式霍普金森压力棒(SHPB)装置对块状金属玻璃(BMG)在室温和高温下的动态压缩行为进行建模和模拟研究的情况。本研究的主要目的是开发和验证能够预测不同温度下 BMG 高应变率响应的构成模型和模拟方法。我们提出了一种考虑到高应变率和高温影响的 BMG 构成模型。通过编写矢量化用户材料 (VUMAT) 子程序,我们在 ABAQUS/显式有限元分析软件中对该模型进行了数值化实现。我们开发了使用 SHPB 设置对 BMG 试样进行动态压缩建模和模拟的方法。本模拟能够正确预测 Zr41.2Ti13.8Cu12.5 Ni10Be22.5 (Vitreloy-1) BMG 在室温和高温动态压缩下与速率无关的响应。此外,本模拟还能正确预测室温下 Zr52.5Cu17.9Ni14.6Al10Ti5(Vitreloy-105)BMG 的负应变速率敏感性(SRS)。最后,本模拟结果正确预测了 Zr64.13Cu15.75Ni10.12Al10 BMG 的破坏应力随温度升高而减小,并表现出最小的正 SRS。本研究首次成功模拟了各种 BMG 在动态压缩、室温和高温条件下的机械响应。特别是成功模拟了实验观察到的某些 BMG 的负 SRS。本研究成果对于设计基于 BMG 的下一代航天器防护罩以减轻空间碎片的超高速撞击影响具有重要意义。Thin-Walled StructuresThe phase-field fracture model enriched by interpolation cover functions for brittle fracture problemsJiye Wang, Liming Zhou, Zhiqiang Gao, Peng Liudoi:10.1016/j.tws.2024.111724针对脆性断裂问题的插值覆盖函数丰富的相场断裂模型In this study, interpolation cover functions were introduced into the phase-field fracture model (PFM) to improve its convergence and efficiency. The traditional PFM has proven to be successful in simulating brittle fracture problems. However, one disadvantage is that it requires a relatively dense mesh. The PFM model enriched by interpolation cover functions (EPFM) was used for numerical fracture analysis under a relatively coarse mesh. The rank deficiency problem caused by the introduction of interpolation cover functions was resolved using the rank deficiency repair technique. Higher gradients were captured by introducing interpolation cover functions without changing the mesh structure. The numerical examples showed the improvement in convergence. The high efficiency of the proposed EPFM was demonstrated through a series of numerical examples. The numerical results of the EPFM and PFM under different length-scale parameters and meshes were also compared. The results showed that the proposed EPFM is an excellent alternative for evaluating engineering fracture problems.本研究在相场断裂模型(PFM)中引入了插值覆盖函数,以提高其收敛性和效率。事实证明,传统的相场断裂模型在模拟脆性断裂问题上是成功的。但其缺点是需要相对密集的网格。通过插值覆盖函数(EPFM)丰富的 PFM 模型被用于在相对较粗的网格下进行断裂数值分析。使用秩缺陷修复技术解决了因引入插值覆盖函数而导致的秩缺陷问题。通过引入插值覆盖函数,在不改变网格结构的情况下捕捉到了更高的梯度。数值实例表明收敛性得到了改善。通过一系列数值示例,证明了所提出的 EPFM 的高效性。此外,还比较了 EPFM 和 PFM 在不同长度尺度参数和网格下的数值结果。结果表明,所提出的 EPFM 是评估工程断裂问题的最佳选择。来源:复合材料力学仿真Composites FEM

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