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【新文速递】2023年11月27日复合材料SCI期刊最新文章

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今日更新:Composite Structures 3 篇,Composites Part A: Applied Science and Manufacturing 3 篇,Composites Science and Technology 3 篇

Composite Structures

Experimental Investigation on Impact Behavior of Curved Sandwich Composites with Chiral Auxetic Core

Dilek ATİLLA YOLCU, Buket OKUTAN BABA

doi:10.1016/j.compstruct.2023.117749

带有手性助剂芯材的曲面三明治复合材料冲击行为的实验研究

The purpose of this study is to evaluate and compare the capability of impact energy absorption of the sandwich panels with various chiral auxetic cores. To this end, flat and curved panels were subjected to impact testing at varying energy levels. Glass fiber-reinforced epoxy composites and PLA material were used as the skins and core of the examined sandwich panels, respectively. The face sheets were produced by the hand-layup method and the auxetic cores with tetrachiral, anti-tetrachiral, and hexachiral configurations were printed using a 3D printer. The wall thickness, node diameter, and ligament length of the cells, as well as the core thickness, were kept constant for all the studied core structures. Flat and curved sandwich panels were obtained by combining the skins and cores produced in flat, 100 mm, 125 mm, and 160 mm radii of curvature with the epoxy used in skin production. Drop weight tests were carried out at impact energies of 10, 25, and 80 J. The contribution of the auxetic core configuration and panel curvature to the impact behavior of the sandwich panel was evaluated by examining the relationships between contact forces and deflection and by the analysis of the energy absorption and failure mode. The comparative evaluations showed that the auxetic core structure and the curvature of the panel have a significant effect on the impact properties of the sandwich panels. It was also observed that the use of tetrachiral cores could be the ideal design option for flat panels loaded at the perforation energy level. For curved panels, it was determined that the use of a hexachiral core configuration was advantageous in terms of more energy absorption capability, while the use of an anti-tetrachiral core structure was more effective in terms of specific energy absorption.

本研究的目的是评估和比较带有各种手性助剂芯材的夹芯板的冲击能量吸收能力。为此,对平板和曲面板进行了不同能量水平的冲击测试。玻璃纤维增强环氧树脂复合材料和聚乳酸材料分别用作受测夹层板的表皮和芯材。面板采用手糊法制作,而四旋翼、反四旋翼和六旋翼结构的助剂芯材则使用三维打印机打印。在所有研究的芯结构中,细胞的壁厚、节点直径和韧带长度以及芯厚度都保持不变。通过将以平面、100 毫米、125 毫米和 160 毫米曲率半径生产的表皮和芯材与表皮生产中使用的环氧树脂相结合,获得了平面和曲面夹层板。通过检查接触力和挠度之间的关系以及分析能量吸收和失效模式,评估了辅助夹芯结构和面板曲率对夹芯板冲击行为的影响。比较评估结果表明,磁芯结构和面板曲率对夹芯板的冲击性能有显著影响。同时还发现,对于以穿孔能量水平加载的平板,使用四螺旋芯材是理想的设计方案。对于弧形面板,使用六螺旋夹芯结构具有更强的能量吸收能力,而使用反四螺旋夹芯结构则能更有效地吸收特定能量。


Quasi-static mechanical behavior of 2.5D woven variable thickness composites

Nan Wang, Weidong Wen, Yipeng Chang, Yu Zhou, Konghan Lu, Hongjian Zhang

doi:10.1016/j.compstruct.2023.117759

2.5D 可变厚度编织复合材料的准静态力学行为

Many special-shaped structural parts have begun to be prepared in aerospace and other fields using 2.5D woven composites. Therefore, two kinds of 2.5D woven variable-thickness composites are designed by reducing the number of yarn layers, called outer reduction yarn woven composites (ORYWC) and inner reduction yarn woven composites (IRYWC). Both variable thickness regions comprise five independent parts, each occupying one or two layers of yarn reduction. In addition, the microstructure of ORYWC and IRYWC is measured using X-ray computed tomography, and the mechanism of geometric deformation during weaving and molding is discussed. Finally, the quasi-static tensile test is conducted to compare and analyze the longitudinal stiffness, tensile strength, and damage mechanism of ORYWC and IRYWC. The results show that the longitudinal stiffness of the five parts of the two structures maintains little difference. The average stiffness and tensile strength of IRYWC decrease by 4.82% and 10.65% compared with ORYWC.

航空航天和其他领域已开始使用 2.5D 编织复合材料制备许多异形结构件。因此,通过减少纱线层数设计出了两种 2.5D 编织变厚度复合材料,分别称为外减纱编织复合材料(ORYWC)和内减纱编织复合材料(IRYWC)。这两种可变厚度区域都由五个独立部分组成,每个部分占据一层或两层还原纱。此外,还使用 X 射线计算机断层扫描技术测量了 ORYWC 和 IRYWC 的微观结构,并讨论了编织和成型过程中几何变形的机理。最后,进行了准静态拉伸试验,以比较和分析 ORYWC 和 IRYWC 的纵向刚度、抗拉强度和损伤机理。结果表明,两种结构五个部分的纵向刚度差别不大。与 ORYWC 相比,IRYWC 的平均刚度和抗拉强度分别降低了 4.82% 和 10.65%。


Optimal design of composite sandwich panel with auxetic reentrant honeycomb using asymptotic equivalent model and PSO algorithm

Peng Xiao, Lei Bin, Riccardo Vescovini, Shi Zheng

doi:10.1016/j.compstruct.2023.117761

利用渐近等效模型和 PSO 算法优化带有辅助再入蜂窝的复合夹芯板的设计

The composite honeycomb sandwich with auxetic reentrant honeycomb (CSP-ARH) is a typical negative Poisson’s ratio structure, which has better mechanical properties than composite structure with positive Poisson’s ratio. In this study, a 2D asymptotic equivalent model (AEM) based on the variational asymptotic method (VAM) is proposed and used to analyze the vibration and buckling problems of CSP-ARH incorporating CFRP facesheets and an aluminum honeycomb core. After validation with 3D finite element results, a particle swarm optimization (PSO) algorithm is applied to optimize the mesoscopic size of composite facesheets and honeycomb core. The primary objectives of the optimization process involve maximizing the buckling load and natural frequency, minimizing the mass while satisfying specific mechanical properties requirements. Moreover, a few additional optimization iterations are performed to find the optimal shape coefficients of the curved fibers in the CFRP facesheets for variable stiffness composite sandwich panels. The shape of the curved fiber is defined using a cubic polynomial function f(x,y) and is described by a 20 × 20 grid of discrete elements. The results indicate that CSP-ARH with optimal curved fibers shapes exhibit superior performance compared to those with straight fibers, with buckling load and natural frequency increased by 8.18% and 7.09%, respectively.

带辅助再入蜂窝的复合蜂窝夹层(CSP-ARH)是一种典型的负泊松比结构,与正泊松比复合结构相比具有更好的力学性能。本研究提出了一种基于变异渐近法(VAM)的二维渐近等效模型(AEM),用于分析包含 CFRP 面板和铝蜂窝芯的 CSP-ARH 的振动和屈曲问题。经三维有限元结果验证后,采用粒子群优化(PSO)算法对复合材料面片和蜂窝芯的中观尺寸进行优化。优化过程的主要目标包括最大化屈曲载荷和固有频率,最小化质量,同时满足特定的机械性能要求。此外,还进行了一些额外的优化迭代,以找到 CFRP 面板中弯曲纤维的最佳形状系数,从而实现可变刚度复合材料夹芯板。弯曲纤维的形状使用三次多项式函数 f(x,y) 来定义,并用 20 × 20 的离散元素网格来描述。结果表明,采用最佳弯曲纤维形状的 CSP-ARH 与采用直纤维的 CSP-ARH 相比性能更优,屈曲载荷和固有频率分别提高了 8.18% 和 7.09%。


Composites Part A: Applied Science and Manufacturing

Clarifying the mechanisms of edge glow generation in CFRP laminates exposed to simulated lightning currents

Shintaro Kamiyama, Takao Okada, Yoshiyasu Hirano, Takeo Sonehara, Hiromitsu Miyaki, Toshio Ogasawara

doi:10.1016/j.compositesa.2023.107932

阐明暴露在模拟雷电流中的 CFRP 层压板边缘辉光的产生机制

This study examines edge glow mechanisms of CFRP laminates exposed to simulated lightning current by performing direct electrical conduction tests. An impulse electric current, in accordance with SAE ARP 5412B, was applied to the laminates. Numerical simulations based on finite element analysis (FEA) were performed to clarify the voltage and temperature distributions of the CFRP laminates. The analytical results were validated using the experimentally obtained I–V characteristics and temperature responses. Resultingly, edge glow was observed in quasi-isotropic but not in unidirectional and cross-ply laminates. The edge glow was suppressed more in silicone oil than in air. When the edge glow did not occur, the numerical simulation results, I–V characteristics, and temperature response, exhibited good agreement with the experimentally obtained results. Contrary to Joule heating, potential differences of several hundred volts between each layer, which cause dielectric breakdown in the testing atmosphere, are the criterion for edge glow formation.

本研究通过直接电导测试,研究了暴露在模拟雷电流下的 CFRP 层压板的边缘发光机制。根据 SAE ARP 5412B 标准,对层压板施加了脉冲电流。在有限元分析(FEA)的基础上进行了数值模拟,以明确 CFRP 层压板的电压和温度分布。分析结果通过实验获得的 I-V 特性和温度响应进行了验证。结果发现,准各向同性层压板出现了边缘辉光,而单向层压板和交叉层压板则没有。边缘辉光在硅油中比在空气中更容易被抑制。当边缘辉光没有出现时,数值模拟结果、I-V 特性和温度响应与实验结果显示出良好的一致性。与焦耳加热相反,每层之间几百伏的电位差是边缘辉光形成的标准,这种电位差会导致测试气氛中的介电击穿。


Intrinsically conductive resin as a functional repair for ECF/CFRP against simulated lighting strike: an experimental study

Li Xiaodong, Yu Zhou, Shintaro Kamiyama, Takao Okada, Tomohiro Yokozeki

doi:10.1016/j.compositesa.2023.107933

 

本征导电树脂作为 ECF/CFRP 的功能性修复材料,可抵御模拟照明冲击:一项实验研究

Non-metallic coatings offer promising applications for protecting carbon fiber-reinforced plastics (CFRP) from lightning, preserving the strengths of epoxy-based composites without galvanic corrosion concerns. This study explores the electrically conductive polyaniline-based resin's dual role: as protective coating and repair solution for traditional ECF/CFRP lightning protection. We evaluated the impact of coating thickness and surface roughness on lightning resistance. A 0.4mm thick coating with a 400-grit pretreatment demonstrated minimal damage after a -40kA simulated lightning strike, maintaining 96% residual strength. Central to this study was the resin's capability as a functional repair for the conventional ECF LSP system. When employed to repair the damaged ECF/CFRP panel, the resin showcased its efficacy by preserving more than 95% of the system's residual strength even after a subsequent -20kA lightning strike. These results indicate the proposed conductive resin could be a new practical repair approach for lightning strike damage to the conventional ECF layer.

非金属涂料在保护碳纤维增强塑料(CFRP)免受雷击方面具有广阔的应用前景,既能保持环氧基复合材料的强度,又不会产生电化学腐蚀问题。本研究探讨了导电聚苯胺基树脂的双重作用:作为传统 ECF/CFRP 防雷保护的保护涂层和修复解决方案。我们评估了涂层厚度和表面粗糙度对抗雷性的影响。经过 400 砂粒预处理的 0.4 毫米厚涂层在遭受 -40kA 模拟雷击后显示出最小的损坏率,并保持了 96% 的残余强度。这项研究的核心是树脂作为传统 ECF LSP 系统功能性修复的能力。当使用该树脂修复受损的 ECF/CFRP 面板时,即使在随后的 -20kA 雷击后,该树脂仍能保持系统 95% 以上的剩余强度,充分展示了其功效。这些结果表明,所提出的导电树脂可以成为一种新的实用修复方法,用于修复传统 ECF 层的雷击损坏。


Estimation of the moisture absorption rate of carbon fiber reinforced plastic using electromagnetic induction testing

Wataru Matsunaga, Satoshi Imai, Yoshihiro Mizutani, Tetsuo Yasuoka, Akira Todoroki

doi:10.1016/j.compositesa.2023.107934

 

利用电磁感应测试估算碳纤维增强塑料的吸湿率

Because moisture absorption changes the permittivities and electrical conductivities of carbon fiber reinforced plastics (CFRPs) with resin layers, electromagnetic induction testing (EIT) was used for evaluating CFRP moisture absorption. Conductivity and permittivity changes were obtained using a finite element analysis (FEA). A moisture-absorption test was conducted to deduce the relationship between the conductivity and moisture-absorption rate. The conductivity corresponding to CFRP moisture absorption was calculated and used in the FEA, while the permittivity corresponding to CFRP moisture absorption was numerically calculated. The simulation suggested that, as CFRPs absorbed moisture, the influence of displacement currents dominated in the EIT output. Finally, CFRP moisture absorption was analyzed using EIT. The results indicated that the EIT output tended to increase with moisture absorption, indicating the dominance of the displacement-current change due to resin moisture absorption in the moisture absorption. These results demonstrate the effectiveness of EIT for evaluating CFRP moisture absorption.

由于吸湿会改变带树脂层的碳纤维增强塑料(CFRP)的介电常数和导电率,因此采用了电磁感应测试(EIT)来评估 CFRP 的吸湿情况。电导率和介电常数的变化是通过有限元分析(FEA)获得的。为了推断电导率和吸湿率之间的关系,还进行了吸湿测试。有限元分析计算并使用了与 CFRP 吸湿率相对应的电导率,同时数值计算了与 CFRP 吸湿率相对应的介电常数。模拟结果表明,随着 CFRP 吸湿,位移电流的影响在 EIT 输出中占主导地位。最后,使用 EIT 分析了 CFRP 吸湿情况。结果表明,EIT 输出随着吸湿量的增加而增加,表明树脂吸湿引起的位移电流变化在吸湿量中占主导地位。这些结果证明了 EIT 在评估 CFRP 吸湿性方面的有效性。


Composites Science and Technology

Highly conductive and mechanically robust MXene@CF core-shell composites for in-situ damage sensing and electromagnetic interference shielding

Yi Hu, Junzhen Chen, Guoyu Yang, Yujun Li, Ming Dong, Han Zhang, Emiliano Bilotti, Jianjun Jiang, Dimitrios G. Papageorgiou

doi:10.1016/j.compscitech.2023.110356

 

用于原位损伤传感和电磁干扰屏蔽的高导电性和机械坚固性 MXene@CF 核壳复合材料

In this work, a new type of carbon fiber reinforced polymer (CFRP) composite was fabricated by introducing MXene nanoparticles onto the surface of carbon fibers (CF) via electrophoretic deposition (EPD) followed by thermal annealing. The MXene-reinforced CF/epoxy composites displayed enhanced mechanical properties and electrical conductivity as well as in-situ damage sensing capability. The uniformly deposited MXene nanoparticles contributed to a considerable enhancement of the flexural strength of CFRPs through hydrogen bonding and mechanical interlocking. The thermal annealing treatment reduced the amount of oxygen groups on the surface of MXene nanoparticles and enabled a 66 % increase of the out-of-plane electrical conductivity and a 20 % improvement of the electromagnetic interference (EMI) shielding effectiveness. The exceptional EMI performance of the core-shell hierarchical microstructure can be ascribed to the polarization of the inhomogeneous interfaces, the dipole polarization, and the conductive loss effect as a result of the presence of annealed MXenes on the surface of CFs.

在这项工作中,通过电泳沉积(EPD)在碳纤维(CF)表面引入 MXene 纳米粒子,然后进行热退火,制备了一种新型碳纤维增强聚合物(CFRP)复合材料。MXene 增强 CF/epoxy 复合材料显示出更强的机械性能、导电性和原位损伤传感能力。均匀沉积的 MXene 纳米粒子通过氢键和机械互锁作用大大提高了 CFRP 的抗弯强度。热退火处理减少了 MXene 纳米粒子表面的氧基团数量,使平面外导电率提高了 66%,电磁干扰(EMI)屏蔽效果提高了 20%。核壳分层微结构优异的电磁干扰性能可归因于非均质界面的极化、偶极子极化和导电损耗效应,这些都是 CF 表面存在退火 MXenes 的结果。


Nucleation and property enhancement mechanism of robust and high-barrier PLA/CNFene composites with multi-level reinforcement structure

Ling Yan, Somia Yassin Hussain Abdalkarim, Xuefei Chen, ZhiMing Chen, Weidong Lu, Jingli Zhu, Meijin Jin, Hou-Yong Yu

doi:10.1016/j.compscitech.2023.110364

 

具有多级增强结构的强韧高阻隔聚乳酸/CNFene 复合材料的成核与性能增强机理

The demand for biopolymer-based green packaging has attracted growing attention because of its outstanding properties and consistency with clean environmental principle, unfortunately, its slow crystallization rate and narrow processing window is challenging. Inspired by combined functions in nanocellulose-based conductive hybrids, this work developed high-performance polylactic acid (PLA) composites using conductive cellulose nanofiber (CNFene). Interestingly, CNFene has multiple functions as highly graphitized carbon and abundant hydroxyl groups, delivering stimulating properties to PLA composites. As nucleating agents, 3wt% CNFene has a carbon layer on the surface combined with a hydrogen bonding network synergistically enhancing the tensile and crystallization properties of PLA-C3, with a tensile strength of ∼ 53.7 MPa, crystallinity of ∼ 33.9 %, and 6.6 °C decrease in the cold crystallization temperature. Additionally, the compatibility between CNFene and PLA can form a multi-level “reinforcement” network structure, further improving thermal stability and barrier properties. The resultant PLA-C3 showed higher thermal decomposition onset temperature(T0), wider melt-processing window (197.6 °C) and extremely lower overall migration levels in ethanol (68.6 μg/kg) and isooctane (16.3 μg/kg), due to that improved interaction between CNFene and PLA positively affects crystallization ability and kinetic/mechanism of PLA to meet the requirements of industrial and green biopackaging applications.

基于生物聚合物的绿色包装因其出色的性能和符合清洁环保原则而受到越来越多的关注,遗憾的是,其缓慢的结晶速度和狭窄的加工窗口是一项挑战。受基于纳米纤维素的导电混合材料综合功能的启发,本研究利用导电纳米纤维素(CNFene)开发了高性能聚乳酸(PLA)复合材料。有趣的是,CNFene 具有高度石墨化碳和丰富羟基的多重功能,可为聚乳酸复合材料提供刺 激特性。作为成核剂,3wt% CNFene 表面的碳层与氢键网络相结合,协同增强了聚乳酸-C3 的拉伸和结晶性能,使其拉伸强度达到 ∼ 53.7 MPa,结晶度达到 ∼ 33.9 %,冷结晶温度降低了 6.6 °C。此外,氯化萘与聚乳酸的相容性可形成多层次的 "增强 "网络结构,进一步提高热稳定性和阻隔性能。所制备的聚乳酸-C3 具有更高的热分解起始温度(T0)、更宽的熔融加工窗口(197.6 °C)以及在乙醇(68.6 μg/kg)和异辛烷(16.3 μg/kg)中更低的整体迁移水平,这是因为改进的氯化萘与聚乳酸之间的相互作用对聚乳酸的结晶能力和动力学/机理产生了积极影响,从而满足了工业和绿色生物包装应用的要求。


Enhancing impact resistance of hybrid structures designed with triply periodic minimal surfaces

Fenglei Li, Jiakang Gan, Long Zhang, Hailun Tan, Eric Li, Bing Li

doi:10.1016/j.compscitech.2023.110365

 

增强采用三周期极小表面设计的混合结构的抗冲击性

The triply periodic minimal surface (TPMS) represents an engineered structure characterized by its mathematically controllable geometric topology and exceptional mechanical properties. This structure offers notable features such as high porosity, specific strength, stiffness, and energy absorption capabilities. Drawing inspiration from the structure of the human tibia, we developed hybrid structures that combine side-by-side, circular, and elliptical connections, utilizing two TPMS types: IWP and Gyroid. Our comprehensive study delves into the impact resistance of these hybrid structures when subjected to high strain rate loading. To conduct our research, we employed selective laser melting (SLM) to fabricate TPMS samples based on AlSi10Mg, and we validated our finite element model through quasi-static compression experiments. By conducting numerical simulations, we analyzed the mechanical properties and deformation patterns of these structures under strain rates of 250 s−1 and 1250 s−1, comparing them to commonly used porous structures such as Honeycomb, FCC, and BCC. Through quantitative analysis utilizing various evaluation indexes, we effectively demonstrated how the design of hybrid structures enhances energy absorption. Furthermore, we discussed the impact of strain rate on the mechanical properties of these structures, and the Gibson-Ashby model accurately predicted the mechanical properties of partial structures. These findings hold significant implications for guiding the design of lightweight porous structures, improving energy absorption, and enhancing impact resistance.

三周期极小表面(TPMS)是一种工程结构,其特点是具有数学可控的几何拓扑结构和优异的机械性能。这种结构具有高孔隙率、比强度、刚度和能量吸收能力等显著特点。我们从人类胫骨的结构中汲取灵感,利用两种 TPMS 类型,开发出了结合并排、圆形和椭圆形连接的混合结构: IWP 和 Gyroid。我们的综合研究深入探讨了这些混合结构在承受高应变率加载时的抗冲击性。为了开展研究,我们采用选择性激光熔融(SLM)技术制造了基于 AlSi10Mg 的 TPMS 样品,并通过准静态压缩实验验证了我们的有限元模型。通过进行数值模拟,我们分析了这些结构在 250 s-1 和 1250 s-1 应变速率下的机械性能和变形模式,并将其与蜂窝、FCC 和 BCC 等常用多孔结构进行了比较。通过利用各种评价指标进行定量分析,我们有效地展示了混合结构的设计如何增强能量吸收。此外,我们还讨论了应变率对这些结构的机械性能的影响,吉布森-阿什比模型准确地预测了部分结构的机械性能。这些发现对于指导轻质多孔结构的设计、改善能量吸收和增强抗冲击性具有重要意义。




来源:复合材料力学仿真Composites FEM
ACTMechanicalSystemInspireSLM振动复合材料化学航空航天离散元材料试验曲面
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【新文速递】2023年11月29日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 1 篇,Journal of the Mechanics and Physics of Solids 2 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 4 篇International Journal of Solids and StructuresToughening mechanisms and damage propagation in Architected-InterfacesMichelle L.S. Hedvard, Marcelo A. Dias, Michal K. Budzikdoi:10.1016/j.ijsolstr.2023.112600结构化界面中的增韧机制和损伤传播We investigate fracture toughness of architected interfaces and their ability to maintain structural integrity and provide stable damage propagation conditions beyond the failure load. We propose theoretical and numerical frameworks to evaluate the fracture properties of architected interfaces sandwiched between two (face) materials. The microscopic geometries of these interfaces are chosen as 2D cells—pillar, tetrahedron, and hexagon—as well as their 3D counterparts—namely, pillar array, octet truss, and Kelvin cell. Our model, both numerical and analytical, exhibits a high level of accuracy in predicting the compliance before failure and failure loads. Novel results are obtained during the damage propagation regime, indicating fulfilment of the so-called fail-safe design. Some of the cell geometries unfold during fracture, thus increasing the failure load and ensuring stable and controlled damage propagation conditions.我们研究了拱形界面的断裂韧性及其保持结构完整性的能力,以及在破坏载荷之外提供稳定破坏传播条件的能力。我们提出了理论和数值框架来评估夹在两种(面)材料之间的拱形界面的断裂特性。这些界面的微观几何形状被选择为二维单元--柱体、四面体和六面体,以及它们的三维对应物--即柱体阵列、八面体桁架和开尔文单元。我们的数值和分析模型在预测破坏前的顺应性和破坏载荷方面都表现出很高的准确性。在破坏传播过程中获得了新的结果,表明实现了所谓的故障安全设计。一些电池的几何形状在断裂过程中展开,从而增加了破坏载荷,确保了稳定和受控的破坏传播条件。Journal of the Mechanics and Physics of SolidsA macroscopic viscoelastic viscoplastic constitutive model for porous polymers under multiaxial loading conditionsMartijn Wismans, Johannes A.W. van Dommelen, Tom A.P. Engels, Lambèrt C.A. van Breemendoi:10.1016/j.jmps.2023.105499多轴加载条件下多孔聚合物的宏观粘弹性粘塑结构模型A macroscopic constitutive model, the Porous Eindhoven Glass Polymer (Porous EGP) model, is presented to describe the deformation behavior of cavitated rubber toughened polymers under multiaxial loading conditions. It is shown that the proposed macroscopic constitutive model is able to describe the non-linear pre-yield regime, strain rate dependence, post-yield behavior (strain softening and hardening) and void evolution for loading conditions ranging from shear to equi-triaxial (pure triaxial) tension and compression. The Porous EGP model is a combination of a well established non-linear viscoelastic viscoplastic model, the Eindhoven Glassy Polymer (EGP) model, and the modified Gurson model. The Gurson model is adopted to determine the equivalent stress and plastic rate of deformation tensor making it depending on the void volume fraction, deviatoric and hydrostatic stress. The macroscopic constitutive model is developed based on the response of realistic 3D representative volume elements (RVEs) containing randomly positioned mono-disperse inclusions. The constitutive behavior of the matrix phase in this full-field model is described by the EGP model, and the cavitated inclusions are idealized as voids. Their response is studied for a range of void volume fractions, multiaxial loading conditions, strain rates and thermodynamic states. The yield behavior of the heterogeneous material depends non-linearly on the macroscopic hydrostatic stress. This response is well captured with the proposed macroscopic constitutive model.本文提出了一种宏观构成模型--多孔埃因霍温玻璃聚合物(Porous EGP)模型,用于描述多轴加载条件下空穴橡胶增韧聚合物的变形行为。研究表明,所提出的宏观构成模型能够描述从剪切到等三轴(纯三轴)拉伸和压缩等加载条件下的非线性屈服前机制、应变速率依赖性、屈服后行为(应变软化和硬化)以及空洞演化。多孔 EGP 模型是一个成熟的非线性粘弹性粘塑模型、埃因霍温玻璃聚合物 (EGP) 模型和改进的 Gurson 模型的组合。Gurson 模型用于确定等效应力和塑性变形率张量,使其取决于空隙体积分数、偏差应力和静水压力。宏观构成模型是根据包含随机定位的单分散夹杂物的现实三维代表体积元素(RVE)的响应建立的。该全场模型中基体相的构成行为由 EGP 模型描述,空化夹杂物被理想化为空隙。研究了一系列空隙体积分数、多轴加载条件、应变率和热力学状态下的响应。异质材料的屈服行为非线性地取决于宏观静水压力。所提出的宏观构成模型很好地捕捉到了这一响应。Fluid-driven slow slip and earthquake nucleation on a slip-weakening circular faultAlexis Sáez, Brice Lecampiondoi:10.1016/j.jmps.2023.105506滑动减弱环形断层上的流体驱动慢滑动和地震成核问题We investigate the propagation of fluid-driven fault slip on a slip-weakening frictional interface separating two identical half-spaces of a three-dimensional elastic solid. Our focus is on axisymmetric circular shear ruptures as they capture the most essential aspects of the dynamics of unbounded ruptures in three dimensions. In our model, fluid-driven aseismic slip occurs in two modes: as an interfacial rupture that is unconditionally stable, or as the quasi-static nucleation phase of an otherwise dynamic rupture. Unconditionally stable ruptures progress through four stages. Initially, ruptures are diffusively self-similar and the interface behaves as if it were governed by a constant friction coefficient equal to the static friction value. Slip then accelerates due to frictional weakening while the cohesive zone develops. Once the latter gets properly localized, a finite amount of fracture energy emerges along the interface. The rupture dynamics is then governed by an energy balance of the Griffith’s type. In this stage, fault slip transitions from a large-toughness to a small-toughness regime due to the diminishing effect of the fracture energy in the near-front energy balance. Ultimately, self-similarity is recovered and the fault behaves again as having a constant friction coefficient, but this time equal to the dynamic friction value. This condition is equivalent to a fault interface operating to leading order with zero fracture energy. When slow slip is the result of a frustrated dynamic instability, slip also initiates self-similarly at a constant peak friction coefficient. The maximum size that aseismic ruptures can reach before becoming unstable can be as small as a critical nucleation radius (shear modulus divided by the slip-weakening rate) and as large as infinity when faults are close to the limit that separates the two modes of aseismic sliding. In the former scenario, earthquake nucleation occurs unaffected by the dynamic friction coefficient. In contrast, the latter scenario exhibits fracture-mechanics behavior, characterized by a finite influx of elastic strain energy being supplied to and dissipated at the rupture front. We provide analytical and numerical solutions for the problem solved over its full dimensionless parameter space, including expressions for relevant length and time scales characterizing the transition between different stages and regimes. Due to its three-dimensional nature, the model enables quantitative comparisons with field observations as well as preliminary engineering design of hydraulic stimulation operations. Existing laboratory and in-situ experiments of fluid injection are briefly discussed in light of our results.我们研究了流体驱动的断层滑移在分隔三维弹性实体两个相同半空间的滑移减弱摩擦界面上的传播。我们的重点是轴对称圆形剪切断裂,因为它们捕捉到了三维无 界断裂动力学的最基本方面。在我们的模型中,流体驱动的地震滑动有两种模式:一种是无条件稳定的界面破裂,另一种是动态破裂的准静态成核阶段。无条件稳定的破裂会经历四个阶段。最初,断裂是扩散性自相似的,界面的行为就像受等于静摩擦系数的恒定摩擦系数支配一样。然后,由于摩擦力减弱,滑动加速,同时形成内聚区。一旦内聚区适当局部化,就会沿界面产生有限的断裂能。随后,断裂动态受格里菲斯型能量平衡的支配。在这一阶段,由于近前能量平衡中断裂能量的递减效应,断层滑移从大韧性机制过渡到小韧性机制。最终,自相似性得到恢复,断层再次表现为具有恒定的摩擦系数,但此时的摩擦系数等于动摩擦值。这种情况相当于断层界面以领先阶运行,断裂能量为零。当缓慢滑动是受挫动不稳定性的结果时,滑动也会以恒定的峰值摩擦系数自类似地开始。地震断裂在变得不稳定之前所能达到的最大尺寸可以小到临界成核半径(剪切模量除以滑动减弱率),而当断层接近将两种地震滑动模式分开的极限时,则可以大到无穷大。在前一种情况下,地震成核不受动态摩擦系数的影响。相比之下,后一种情况则表现出断裂力学行为,其特征是有限的弹性应变能流入破裂前沿并在破裂前沿耗散。我们提供了该问题在其全无量纲参数空间内的分析和数值解决方案,包括相关长度和时间尺度的表达式,这些表达式表征了不同阶段和状态之间的过渡。由于该模型具有三维性质,因此可以与现场观测结果进行定量比较,并对水力激发作业进行初步工程设计。根据我们的研究结果,对现有的实验室和现场注液实验进行了简要讨论。International Journal of PlasticityCrystal plasticity modeling of electropulsing induced plasticity in metalsYang Yang, Rongshan Qin, Yalin Dong, Jian Wang, Chang Yedoi:10.1016/j.ijplas.2023.103828电脉冲诱导金属塑性的晶体塑性模型A crystal plasticity model incorporating the effects of magnetoplasticity, electron-wind, imbalance of charges near grain boundaries and Joule heating in high frequency short duration electric current pulsed metals has been developed for metals with a face center cubic (FCC) structure. The model decouples the athermal and thermal effects on dislocation activity and quantifies their effects on flow stress. The Joule heating affects the thermal activation in plastic deformation. The magnetoplasticity and electron-wind reduce the slip barrier or contribute additional force to assist dislocation motion. Imbalance of charges near grain boundaries may amplify or minimize the contribution of thermal or other athermal effects. The developed crystal plasticity model has been implemented in DAMASK and verified by simulating electroplasticity in aluminum. The results reveal that the magnetoplasticity reduces flow stress and the reduction increases with the peak current density. Joule heating is generally less important during the processing due to the short pulse duration but becomes more significant when the frequency goes up. The impact of imbalance of charges near grain boundaries on Joule heating depends on the thickness of grain boundaries, the distribution of current density and conductivity, while it always reduces the effect on magnetoplasticity. The electron-wind effect on flow stress is negligible compared to the other three factors. This work provides some new insights in the understanding of electroplasticity in metals.针对具有面心立方(FCC)结构的金属,我们开发了一种晶体塑性模型,其中包含了磁塑性、电子风、晶界附近电荷不平衡以及高频短时脉冲电流金属中焦耳热的影响。该模型将差排活动的非热效应和热效应分离开来,并量化了它们对流动应力的影响。焦耳加热影响塑性变形中的热激活。磁塑性和电子风降低了滑移障碍或提供了额外的力来帮助差排运动。晶界附近的电荷失衡可能会放大或缩小热效应或其他非热效应的贡献。开发的晶体塑性模型已在 DAMASK 中实施,并通过模拟铝的电塑性得到验证。结果显示,磁塑性降低了流动应力,且降低幅度随峰值电流密度的增加而增大。在加工过程中,由于脉冲持续时间较短,焦耳热一般不太重要,但当频率升高时,焦耳热变得更加重要。晶界附近电荷不平衡对焦耳加热的影响取决于晶界厚度、电流密度分布和电导率,而对磁塑性的影响总是减弱。与其他三个因素相比,电子风对流动应力的影响可以忽略不计。这项研究为理解金属中的电塑性提供了一些新的见解。Thin-Walled StructuresStatic behavior of corrugated steel-shotcrete composite archesZhanming Wu, Yuyin Wang, Yong Mei, Faqi Liu, Changyong Liudoi:10.1016/j.tws.2023.111429波纹钢-混凝土复合拱的静态行为A new type of corrugated steel-shotcrete composite (CSSC) arch is proposed, which possesses the advantages of both high load-bearing capacity and ease of construction. Thus it is particularly suitable for bridges, culverts, shafts, and other projects. In this study, the static behavior of the CSSC arch under three-point loading was investigated experimentally and numerically. Four specimens with different rise-span ratios (1/2, 1/8), different spans (3m, 6m), and different locations of shotcrete lining (shotcrete outer lining, shotcrete inner lining) were tested. The test results show that the load-bearing capacity and initial stiffness of the CSSC arch could reach 6.8 times and 13.9 times that of the corrugated steel (CS) arch, respectively. When the load was less than 0.4 times the load-bearing capacity of the specimens, CS and shotcrete worked together. After that, the composite effect between CS and shotcrete was weakened. The ductility of the shotcrete outer lining CSSC arch is better than that of the shotcrete inner lining CSSC arch. A finite element model (FEM) was developed to investigate the influences of key parameters on the load-bearing capacity, including the thickness of materials, the strength of materials, the rise-span ratios and spans. Furthermore, calculation methods were proposed to predict the axial compressive capacity of the CSSC arch.本文提出了一种新型波纹钢-混凝土复合拱(CSSC),它具有承载能力高、施工简便等优点。因此,它特别适用于桥梁、涵洞、竖井等工程。本研究采用实验和数值方法研究了 CSSC 拱在三点荷载作用下的静态行为。测试了四个不同升跨比(1/2、1/8)、不同跨度(3 米、6 米)和不同喷射混凝土衬砌位置(喷射混凝土外衬、喷射混凝土内衬)的试件。试验结果表明,中船重工拱桥的承载力和初始刚度分别达到波纹钢拱桥的 6.8 倍和 13.9 倍。当荷载小于试件承载力的 0.4 倍时,CS 和喷射混凝土 共同起作用。之后,CS 和喷射混凝土的复合效应减弱。喷射混凝土外衬 CSSC 拱桥的延性优于喷射混凝土内衬 CSSC 拱桥。为研究材料厚度、材料强度、升跨比和跨度等关键参数对承载能力的影响,建立了有限元模型(FEM)。此外,还提出了预测 CSSC 拱桥轴向抗压能力的计算方法。Mechanics and Validation Tests of a Post-Tensioned Self-Centering Brace with Adjusted Stiffness and Deformation Capacities Using Disc SpringsChung-Che Chou, Li- Yu Huangdoi:10.1016/j.tws.2023.111430利用碟形弹簧调整刚度和变形能力的后张自定心支撑的力学性能和验证试验Self-centering braces have been developed to reduce the residual deformation of steel frames in earthquakes. The brace has a higher elastic axial stiffness before the activation, which may result in a higher base shear for frame design. This work was aimed to develop a new post-tensioned self-centering brace (PT-SCB) with adjusted stiffness and deformation capabilities such that the brace could be designed based on a specified yield or ultimate frame drift. Combining disc springs and one of the compression members together in the original SCB could achieve new structural characteristics, providing an alternative to tune the axial stiffness and deformation. This work first introduces the mechanics and deformation mechanism of the proposed SCB and performs a parametric study to investigate the effect of disc spring stacks on the hysteretic response of SCBs. A test program is then conducted on cyclic tests of disc spring stacks in different serial and parallel combinations and two PT-SCBs. Each 3800 mm-long brace is composed of high-strength steel tendons, compression steel members, disc spring stacks, and bolted friction device. The hysteretic responses of the new SCB with different design parameters are used to validate the mechanics and ability of the axial stiffness and deformation adjustment.自定心支撑的开发是为了减少钢框架在地震中的残余变形。自定心支撑在启动前具有较高的弹性轴向刚度,这可能会导致框架设计的基础剪力增大。这项工作的目的是开发一种新型后张法自定心支撑(PT-SCB),它具有调整刚度和变形能力,可以根据指定的屈服或极限框架漂移进行设计。将碟形弹簧和原 SCB 中的一个压缩构件组合在一起可实现新的结构特性,为调整轴向刚度和变形提供了另一种选择。本研究首先介绍了拟议 SCB 的力学和变形机理,并进行了参数研究,以探讨碟形弹簧叠层对 SCB 滞后响应的影响。然后,对不同串联和并联组合的碟形弹簧组和两个 PT-SCB 进行了循环测试。每个 3800 毫米长的支撑由高强度钢筋、压缩钢构件、碟形弹簧组和螺栓摩擦装置组成。采用不同设计参数的新型 SCB 的滞后响应验证了轴向刚度和变形调整的力学性能和能力。Fatigue crack growth and life assessment of full penetration U-rib welded joints considering residual stressesHao Zheng, Zhiyu Jie, Lexin Zhang, Wei Ludoi:10.1016/j.tws.2023.111426考虑残余应力的全熔透 U 形肋焊接接头的疲劳裂纹增长和寿命评估The combination of cyclic stresses and welding residual stresses (WRS) can significantly contribute to fatigue cracking in steel bridge decks. This study aims to investigate the effect of WRS on the fatigue life and crack propagation of single-sided and full penetration double-sided U-rib welded joints through experimental and numerical methods. Fatigue tests were conducted to study fatigue crack initiation and propagation behavior. Utilizing the ABAQUS software, a thermoelastic-plastic finite element method was employed to determine the residual stress distribution. Subsequently, based on linear elastic fracture mechanics (LEFM), fatigue crack propagation and life assessment were performed using ABAQUS and FRANC3D software under the coupling of residual stresses and external cyclic stresses. Findings reveal that WRS play a crucial role in fatigue life by altering the effective stress ratio during fatigue crack growth. The effective stress ratio ranges from 0.15 to 0.57, while the changing trends differ between single-sided and double-sided U-rib welded joints. The fatigue crack growth rate of double-sided U-rib welded joints is lower compared to single-sided U-rib welded joints with the same deck thickness. Furthermore, the introduction of WRS induces a mixed mode I, II, and III fracture at the outer weld toe of the U rib, with mode I fracture predominating, which leads to a deviation in the crack propagation path. The fatigue life prediction results agree well with experimental findings when considering WRS. Importantly, these predictions tend to be conservative, thereby ensuring safety and reliability in engineering applications.循环应力和焊接残余应力(WRS)的共同作用会显著导致钢桥面的疲劳开裂。本研究旨在通过实验和数值方法研究 WRS 对单面和全熔透双面 U 形肋焊接接头的疲劳寿命和裂纹扩展的影响。通过疲劳试验研究了疲劳裂纹的起始和扩展行为。利用 ABAQUS 软件,采用热弹塑性有限元法确定了残余应力分布。随后,基于线性弹性断裂力学(LEFM),使用 ABAQUS 和 FRANC3D 软件在残余应力和外部循环应力的耦合下进行了疲劳裂纹扩展和寿命评估。研究结果表明,WRS 通过改变疲劳裂纹生长过程中的有效应力比,对疲劳寿命起着至关重要的作用。有效应力比从 0.15 到 0.57 不等,而单面和双面 U 形肋焊接接头的变化趋势各不相同。与相同桥面厚度的单面 U 形肋焊接接头相比,双面 U 形肋焊接接头的疲劳裂纹增长速率较低。此外,WRS 的引入在 U 形肋外焊趾处诱发了 I、II 和 III 三种模式的混合断裂,其中以 I 模式断裂为主,这导致了裂纹扩展路径的偏差。当考虑到 WRS 时,疲劳寿命预测结果与实验结果非常吻合。重要的是,这些预测结果趋于保守,从而确保了工程应用的安全性和可靠性。Experimental and numerical investigations of a novel parallel double-stage crawler-track-shaped shear damperCantian Yang, Linlin Xie, Qiang Liu, Aiqun Li, Xinyu Wang, Qianmin Liudoi:10.1016/j.tws.2023.111428新型平行双级履带式剪切阻尼器的实验和数值研究In this study, a novel parallel double-stage crawler-track-shaped shear damper (PDCSD) was developed, which is fabricated using thin-walled steel plates. An asynchronized double-stage working mechanism was achieved based on the parallel energy dissipation (inner and outer crawler-track-shaped steel plates), restraining (upper and lower restraining plates), and load transfer (outer and inner blockers with initial clearance) systems. Accordingly, theoretical equations for the skeleton curve of the PDCSD and the design load for the load transfer system were proposed. The double-stage working mechanism and performance of the PDCSD were verified based on full-scale seismic and fatigue performance tests. Subsequently, based on refined finite element analyze, the working mechanism of the PDCSD was revealed and the theoretical equations were validated. A simplified model of the PDCSD with an emphasize on the hysteretic behavior was conclusively recommended and validated against the test and simulation results obtained from the refined numerical models, providing an accurate and efficient approach for the seismic response control of structures equipped with PDCSDs.本研究开发了一种新型平行双级履带式剪切阻尼器(PDCSD),采用薄壁钢板制造。在平行消能(内、外履带式钢板)、约束(上、下约束板)和载荷传递(具有初始间隙的外、内阻挡块)系统的基础上,实现了不同步双级工作机制。据此,提出了 PDCSD 的骨架曲线和载荷传递系统设计载荷的理论方程。基于全尺寸抗震和疲劳性能试验,对 PDCSD 的双级工作机制和性能进行了验证。随后,基于精细的有限元分析,揭示了 PDCSD 的工作机理并验证了理论方程。根据细化数值模型获得的试验和模拟结果,最终推荐并验证了一种侧重于滞后行为的 PDCSD 简化模型,为配备 PDCSD 的结构的地震响应控制提供了一种准确而有效的方法。来源:复合材料力学仿真Composites FEM

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