首页/文章/ 详情

【新文速递】2023年11月26日复合材料SCI期刊最新文章

1天前浏览154

今日更新:Composite Structures 1 篇,Composites Part A: Applied Science and Manufacturing 5 篇,Composites Science and Technology 1 篇

Composite Structures

Experimental investigation on a FRCM bio-composite for sustainable retrofitting of masonry buildings

Marco Corradi, Stefano Agnetti, Chiara Quintaliani, Emanuela Speranzini

doi:10.1016/j.compstruct.2023.117753

用于砌体建筑可持续改造的 FRCM 生物复合材料实验研究

Strengthening masonry structures by using green and natural materials has received increasing attention. Natural fibers can be obtained from vegetables, animals or mineral sources and can be used to meet modern buildings safety standards and to reduce carbon dioxide emissions. This paper presents a novel method to strengthen masonry buildings through the application of a mortar coating reinforced with natural fibers made of a jute or a basalt grid. This class of materials is known as Fiber Reinforced Cementitious Matrix (FRCM). FRCM composites can produce an increment in the mechanical properties of the masonry members and contribute to the thermal-acoustic insultation of the building envelope. The mortar coating is made of a hydraulic lime: to increase thermal properties this was admixed with short spelt fibers. Both matrix (lime mortar) and fibrous material were initially mechanically and thermally characterized. Laboratory tests have been carried out to study the bond characteristics between the FRCM composite and brickwork masonry. It was found the low mechanical properties of jute fibers are aggravated by a low FRCM-to-masonry bonding, making difficult to use this material for structural retrofit. On opposite, basalt fibers exhibit high mechanical properties and their use in conservation is surely promising and interesting.

使用绿色天然材料加固砌体结构已受到越来越多的关注。天然纤维可从蔬菜、动物或矿物中获取,可用于满足现代建筑安全标准和减少二氧化碳排放。本文介绍了一种新方法,通过使用黄麻或玄武岩网格天然纤维加固砂浆涂层来加固砌体建筑。这类材料被称为纤维增强水泥基质(FRCM)。纤维增强水泥基复合材料可提高砌体构件的机械性能,并有助于减轻建筑外墙的热声损伤。砂浆涂层由水力石灰制成:为了提高热性能,砂浆中加入了短纤维。基体(石灰砂浆)和纤维材料最初都具有机械和热特性。为了研究 FRCM 复合材料与砖砌体之间的粘结特性,还进行了实验室测试。结果发现,黄麻纤维的机械性能较低,而 FRCM 与砌体之间的粘结力较低,这使得这种材料难以用于结构改造。与此相反,玄武岩纤维则表现出较高的机械性能,将其用于保护工程无疑是很有前景和意义的。


Composites Part A: Applied Science and Manufacturing

Deconsolidation of carbon fiber-reinforced PEKK laminates: 3D real-time in situ observation with synchrotron X-ray microtomography

Luc Amedewovo, Laurent Orgéas, Basile de Parscau du Plessix, Nicolas Lefevre, Arthur Levy, Steven Le Corre

doi:10.1016/j.compositesa.2023.107917

碳纤维增强 PEKK 层压板的解固:利用同步辐射 X 射线显微层析技术进行三维实时原位观测

Deconsolidation of carbon-fibre reinforced thermoplastic laminate occurs while (pre)heating the materials during their forming processes. Pores nucleate, grow and lead to degradations of mechanical properties. Here, a new experimental device was developed and installed inside a synchrotron beamline (dedicated to fast X-ray microtomography). Pore nucleation and growth was observed in 3D, real-time and in situ while heating Carbon/PEKK laminate samples. The time evolution of sample deconsolidation strain, porosity, as well as number, size and morphology of pores was assessed. Nucleation and growth is observed above the glass transition temperature and enhanced with initial moisture content. Drastic deconsolidation when approaching melting temperature is thought to be driven by internal stress in the laminate. The data provided may be used as input for modeling purposes or for validation of existing models.

碳纤维增强热塑性塑料层压板在成型过程中进行(预)加热时会出现脱固现象。孔隙成核、生长并导致机械性能下降。在此,我们开发了一种新的实验装置,并将其安装在同步辐射光束线(专用于快速 X 射线显微层析成像)内。在加热碳/PEKK 层压板样品时,对孔隙成核和生长进行了三维、实时和原位观测。评估了样品脱固应变、孔隙率以及孔隙数量、大小和形态的时间演变。在玻璃转化温度以上观察到了成核和生长现象,并随着初始含水量的增加而增强。接近熔化温度时的急剧解固被认为是由层压板中的内应力驱动的。所提供的数据可用于建模或验证现有模型。


Bioinspired Hybrid Helical Structure in Lobster Homarus Americanus: Enhancing Penetration Resistance and Protective Performance

Xiaofang Zhang, Yanan Yuan

doi:10.1016/j.compositesa.2023.107927

 

龙虾中的生物启发混合螺旋结构:增强抗穿透性和保护性能

The high impact and penetration resistance of the cuticle in the lobster Homarus americanus can be attributed to its unique twisted plywood structure. Hybridization of two helical structures was observed in the exoskeleton, with different pitch angles and ply thickness of the exocuticle and endocuticle within the exoskeleton. Given the survival challenges posed by the natural environment, it is worthwhile to study why it evolved into a hybrid helical rather than a uniform helical structure. In light of this, we have proposed an innovative bionic hybrid helical structure design strategy that goes beyond simply reducing the pitch angle. In this paper, we replicated complex biological microstructures by introducing two types of pitch angles and ply thicknesses for regional configurations. Quasi Static Indentation (QSI) full-penetration experiments were conducted. Experimental results revealed that the exocuticle with a large pitch angle and small ply thickness possesses a higher knee load under the penetration test, which provides a higher initial damage threshold. On the other hand, the endocuticle with a small pitch angle and large ply thickness induces higher damage dissipation, which provides superior protective performance. These research findings demonstrate that ply hybridization can be a promising method for microstructure design to improve the penetration resistance of thin laminates and serve as a reference for developing more refined gradient helical structure designs.

美洲龙虾(Homarus americanus)的角质层具有很高的抗冲击和抗穿透性,这要归功于其独特的扭曲胶合板结构。在外骨骼中观察到两种螺旋结构的杂交,外骨骼中的外表皮层和内表皮层具有不同的节距角和层厚。鉴于自然环境带来的生存挑战,值得研究它为什么会进化成一种混合而不是均匀的螺旋结构。有鉴于此,我们提出了一种创新的仿生混合螺旋结构设计策略,而不仅仅是简单地减小螺距角。在本文中,我们通过引入两种间距角和层厚的区域配置,复 制了复杂的生物微结构。我们进行了准静态压痕(QSI)全穿透实验。实验结果表明,间距角大、层厚小的外茧在穿透试验中具有更高的膝部载荷,从而提供了更高的初始损伤阈值。另一方面,间距角小、层厚大的内层材料能产生更高的损伤耗散,从而提供更优越的保护性能。这些研究结果表明,层间杂化是一种很有前途的微结构设计方法,可提高薄层板的抗穿透性,并为开发更精细的梯度螺旋结构设计提供参考。


Mixed Modes Crack Propagation of Orthogonal Woven-layer in Carbon/Aramid/Epoxy Laminates

Yuan Fu, Wei Yan Lv, Wen Hai Sun, Li Min Xu, Hui Guo

doi:10.1016/j.compositesa.2023.107929

碳/芳纶/环氧层压板中正交编织层的混合模式裂纹扩展

This work presents a combined formulation for the fracture model of carbon/aramid fiber reinforced plastic woven laminates (CARPWLs). The structural crack is implemented based on Extended Finite Element Method (XFEM) and Cohesive Zone Model (CZM) with a mixed-mode loading. This work considers four types of fracture mechanics CARPWLs testing samples, each composed of five woven layers with different stacking sequences. The loading device for mixed modes is achieved through a fixture with a secondary level rotating wheel configured with samples via bolting. Additionally, a new velocity control servo script for driving force is proposed to obtain R-curves during the fracture process of Type I, II and III. The energy release rate G for I/II/III mixed modes are also studied by experimental and numerical methods on account of fracture mechanics. The numerical verification performs highly accuracy to experiments, and it provides an efficiency approach for evaluating failure response of laminates.

本研究提出了碳/芳纶纤维增强塑料编织层压板(CARPWLs)断裂模型的组合公式。结构裂纹是基于扩展有限元法(XFEM)和混合模式加载的内聚区模型(CZM)实现的。本研究考虑了四种类型的断裂力学 CARPWLs 测试样本,每种样本由五层编织层组成,每层编织层的堆叠顺序各不相同。混合模式加载装置是通过一个带有二级旋转轮的夹具实现的,该夹具通过螺栓与样品连接。此外,还提出了一种新的驱动力速度控制伺服脚本,以获得 I、II 和 III 型断裂过程中的 R 曲线。根据断裂力学,还通过实验和数值方法研究了 I/II/III 混合模式的能量释放率 G。数值验证结果与实验结果具有很高的精确度,为评估层压板的破坏响应提供了一种有效的方法。


Pre-compositing polyetherketoneketone with short-cut carbon fibers into advanced powder materials toward composites with fully-adhered interfaces

Xin Wang, Yiting Qu, Junlei Bai, Fujun Xu, Bin Ding, Xiaohua Zhang

doi:10.1016/j.compositesa.2023.107930

将聚醚醚酮与短切碳纤维预复合到先进的粉末材料中,形成具有全粘合界面的复合材料

It is challenging to realize intimate interface between reinforcement and matrix using powder materials, due to the high melting points and melt viscosities of thermoplastics like polyaryletherketones. Herein, a solution-based strategy is proposed to prepare pre-composition in powders, and using them, full and tight fiber–matrix bounding is formed in the final composites. Owing to the dissolubility of polyetherketoneketone (PEKK), short-cut carbon fibers (CFs) are uniformly introduced into the solution and fully covered by PEKK, i.e., the pre-composition. The composite powders lead to structural uniformity, full utilization of CF surfaces, and avoidance of CF aggregation. The hot-compressed beams exhibit remarkably enhanced tensile and flexural strengths (135.5 and 173.7 MPa), more than 30% and 60% higher than those of the pure PEKK. Meanwhile, they possess high tensile and flexural strains at break up to 5.5% and 11.4%, respectively, enhanced crystallinity up to 17.7%, and high thermal conductivity of 0.26–0.29 Wm−1 K−1. The pre-composition also exhibits other advantages, such as the higher powder flowability, reduced steps of high-temperature processing, and superior anti-abrasion ability and enhanced thermal stability of composite beams.

由于聚芳醚酮等热塑性塑料的熔点和熔体粘度较高,使用粉末材料实现增强体与基体之间的紧密结合具有挑战性。本文提出了一种基于溶液的策略来制备粉末中的预复合材料,并利用它们在最终复合材料中形成完整而紧密的纤维-基体结合。由于聚醚醚酮酮(PEKK)的可溶性,短切碳纤维(CF)被均匀地引入溶液中,并被聚醚醚酮酮(PEKK)完全覆盖,即预合成。这种复合粉末具有结构均匀、充分利用碳纤维表面和避免碳纤维聚集的特点。热压梁的抗拉和抗弯强度(135.5 和 173.7 兆帕)显著提高,比纯 PEKK 高出 30% 和 60% 以上。同时,它们的拉伸和弯曲断裂应变分别高达 5.5% 和 11.4%,结晶度提高到 17.7%,导热系数高达 0.26-0.29 Wm-1 K-1。这种预复合材料还具有其他优点,如粉末流动性更高、减少了高温加工步骤、抗磨损能力更强以及增强了复合梁的热稳定性。


High-performance chlorinated polyvinyl chloride/polyurea nanocomposite foam with excellent solvent resistance, flame-triggered shape memory effect and its upcycling

Jiangan You, Ling Cai, Ronghua Yu, Haiping Xing, Jian Xue, Ying Li, Zhiwei Jiang, Dongmei Cui, Tao Tang

doi:10.1016/j.compositesa.2023.107931

 

高性能氯化聚氯乙烯/聚脲纳米复合泡沫,具有优异的耐溶剂性、火焰触发的形状记忆效果和可循环利用性

Facing the global environmental pollution crisis related to waste plastics, the recyclable design of polymer materials and composites, especially large commodities, is the most effective and fundamental solution. Herein, an upcycling chlorinated polyvinyl chloride/polyurea (CPVC/PUA) nanocomposite foam was designed by means of the “plasticizing-foaming-reinforcing” (PFR) strategy combined with catalytic carbonization of CPVC/PUA foams. On one hand, the foam with ultra-high expansion ratio (62 times) can be facilely prepared in supercritical CO2 at lower temperature, benefited of the reactive plasticizing function of PUA monomer-polymeric methylene diphenyldiisocyanate (PMDI). On the other hand, the obtained foam is reinforced by PMDI crosslinking reaction to in situ form nano-PUA phase in the CPVC matrix and realizing robust and superior solvent resistance and flame-triggered shape memory effect. Moreover, the foam possesses remarkable ablation resistance, which is attributed to super carbonization capacity of CPVC catalyzed by PUA. This carbonization behavior endows the foam directly upcycle into functional carbon foam accompanied by the formation of HCl gas and functional aromatics. The obtained carbon foam shows attractive electromagnetic interference shielding performance, which also may be used as potential carbon source or catalyst of producing vinyl chloride monomer in the chlor-alkali industry, especially in China.

面对与废塑料相关的全球环境污染危机,高分子材料和复合材料(尤其是大宗商品)的可回收设计是最有效、最根本的解决方案。本文采用 "塑化-发泡-增强"(PFR)策略,结合 CPVC/PUA 泡沫的催化碳化,设计了一种可循环利用的氯化聚氯乙烯/聚脲(CPVC/PUA)纳米复合泡沫。一方面,得益于 PUA 单体-聚亚甲基二苯基二异氰酸酯(PMDI)的反应增塑功能,可在超临界 CO2 中以较低温度轻松制备出具有超高膨胀比(62 倍)的泡沫。另一方面,所获得的泡沫通过 PMDI 交联反应在 CPVC 基体中原位形成纳米 PUA 相,从而增强了泡沫的强度和优异的耐溶剂性,并实现了火焰触发的形状记忆效果。此外,泡沫还具有显著的耐烧蚀性,这归功于 CPVC 在 PUA 催化下的超强碳化能力。这种碳化行为使泡沫在形成 HCl 气体和功能芳烃的同时,直接上升循环为功能碳泡沫。所获得的碳泡沫具有极佳的电磁干扰屏蔽性能,也可用作氯碱工业(尤其是中国)生产氯乙烯单体的潜在碳源或催化剂。


Composites Science and Technology

A multi-fidelity data-driven model for highly accurate and computationally efficient modeling of short fiber composites

Hon Lam Cheung, Mohsen Mirkhalaf

doi:10.1016/j.compscitech.2023.110359

 

用于短纤维复合材料高精度和高效计算建模的多保真度数据驱动模型

To develop physics-based models and establish a structure–property relationship for short fiber composites, there are a wide range of micro-structural properties to be considered. To achieve a high accuracy, high-fidelity full-field simulations are required. These simulations are computationally very expensive, and any single analysis could potentially take days to finish. A solution for this issue is to develop surrogate models using artificial neural networks. However, generating a high-fidelity data set requires a huge amount of time. To solve this problem, we used transfer learning technique, a limited amount of high-fidelity full-field simulations, together with a previously developed recurrent neural network model trained on low-fidelity mean-field data. The new RNN model has a very high accuracy (in comparison with full-field simulations) and is remarkably efficient. This model can be used not only for highly efficient modeling purposes, but also for designing new short fiber composites.

要为短纤维复合材料开发基于物理的模型并建立结构-性能关系,需要考虑广泛的微观结构特性。为了达到高精度,需要进行高保真全场模拟。这些模拟的计算成本非常昂贵,任何一项分析都可能需要数天才能完成。解决这一问题的办法是利用人工神经网络开发替代模型。然而,生成高保真数据集需要大量时间。为了解决这个问题,我们使用了迁移学习技术、有限的高保真全场模拟,以及之前开发的以低保真平均场数据为基础训练的递归神经网络模型。新的循环神经网络模型具有非常高的精度(与全场模拟相比)和显著的效率。该模型不仅可用于高效建模,还可用于设计新型短纤维复合材料。




来源:复合材料力学仿真Composites FEM
ACTMechanicalInspireMarcMAGNET断裂复合材料建筑裂纹材料仿生控制试验螺栓
著作权归作者所有,欢迎分享,未经许可,不得转载
首次发布时间:2024-11-03
最近编辑:1天前
Tansu
签名征集中
获赞 0粉丝 0文章 143课程 0
点赞
收藏
作者推荐

【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

未登录
还没有评论
课程
培训
服务
行家
VIP会员 学习 福利任务 兑换礼品
下载APP
联系我们
帮助与反馈