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【新文速递】2024年2月1日复合材料SCI期刊最新文章

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

Composites Part A: Applied Science and Manufacturing

A critical plane approach for multiaxial fatigue life prediction of short fiber reinforced thermoplastic composites

Mohammad Amjadi, Ali Fatemi

doi:10.1016/j.compositesa.2024.108050

短纤维增强热塑性复合材料多轴疲劳寿命预测的临界面方法

The usage of short fiber reinforced thermoplastics has been increasing in many industries recently. These composites have many advantages such as high specific strength, lightweight, wear and rust resistance, high stiffness, fast processing rate, and relatively low manufacturing cost. Multiaxial cyclic loading and non-proportionality between different loading sources are inevitable in many applications with such materials. In this study, the multiaxial fatigue behavior of short glass fiber reinforced thermoplastics under different environmental and loading conditions is modeled using a critical plane-based damage approach. This model was recently used for uniaxial fatigue life prediction of Short Fiber Reinforced Thermoplastic Composites. In this paper the model is applied to a large amount of experimental multiaxial fatigue data, demonstrating significantly better correlations than other models used in the literature. The effects of fiber orientation, stress state, mean stress, and stress concentration on multiaxial fatigue behavior are considered in the model. Temperature and frequency effects on multiaxial fatigue behavior were also included by applying the proposed damage model into a general fatigue model. Model predictions are presented and discussed by comparing them with experimental data from the literature.

近来,短纤维增强热塑性塑料在许多行业中的使用日益增多。这些复合材料具有许多优点,如比强度高、重量轻、耐磨防锈、刚度高、加工速度快以及制造成本相对较低。在这类材料的许多应用中,多轴循环加载和不同加载源之间的非比例性是不可避免的。本研究采用基于临界面的损伤方法,对短玻璃纤维增强热塑性塑料在不同环境和加载条件下的多轴疲劳行为进行建模。该模型最近被用于短纤维增强热塑性复合材料的单轴疲劳寿命预测。本文将该模型应用于大量多轴疲劳实验数据,结果表明其相关性明显优于文献中使用的其他模型。该模型考虑了纤维取向、应力状态、平均应力和应力集中对多轴疲劳行为的影响。通过将提出的损伤模型应用到一般疲劳模型中,还考虑了温度和频率对多轴疲劳行为的影响。模型预测结果与文献中的实验数据进行了比较和讨论。


A new interface bonding improvement method combined with precipitation and hot-pressing process to ameliorate the defects of para aramid paper

Ping Xie, Na Li, Kairong Zhao, Yutong Cao, Junrong Yu, Yan Wang, Zuming Hu

doi:10.1016/j.compositesa.2024.108052

 

结合沉淀和热压工艺的界面粘合改进新方法可改善对位芳纶纸的缺陷

At present, the mechanical properties of para aramid paper (PPTA paper) are still severely challenged since interface bonding defects. In this work, a novel method for improving the interface bonding of PPTA paper was proposed by introducing m-phenylenediamine (MPD) into PPTA molecular chain by copolymerization. Result showed that the addition of MPD could monitor the rigidity and glass transition temperature (Tg) of PPTA. The Tg generated by the copolymerized modified PPTA precipitated fibers (MAPFs) realized micro-melting bonding with adjacent fibers during hot-pressing process. Further optimization of MAPFs precipitation and hot-pressing process improved the tensile strength of paper. Results indicated that the tensile strength of paper made of MAPFs with 60% MPD far beyond PPTA paper (PAP), and was 1.07 times of Nomex paper. The method provides a reference value for the application of high performance PAP in lightweight and high strength fields, broadening the application field of PAP as well.

目前,对位芳纶纸(PPTA 纸)的机械性能仍然受到界面粘合缺陷的严重挑战。本研究提出了一种改善 PPTA 纸界面粘结性的新方法,即通过共聚在 PPTA 分子链中引入间苯二胺(MPD)。结果表明,MPD 的加入可监测 PPTA 的刚性和玻璃化转变温度(Tg)。共聚改性 PPTA 沉淀纤维(MAPFs)产生的 Tg 在热压过程中实现了与相邻纤维的微熔粘合。进一步优化 MAPFs 的沉淀和热压工艺可提高纸张的抗张强度。结果表明,60% MPD 的 MAPFs 纸张的抗张强度远远超过 PPTA 纸(PAP),是 Nomex 纸的 1.07 倍。该方法为高性能 PAP 在轻质高强领域的应用提供了参考值,同时也拓宽了 PAP 的应用领域。


Composites Part B: Engineering

An accurate forming model for capturing the nonlinear material behaviour of multilayered binder-stabilised fabrics and predicting fibre wrinkling

Peter H. Broberg, Esben Lindgaard, Adam J. Thompson, Jonathan P.-H. Belnoue, Stephen R. Hallett, Brian L.V. Bak

doi:10.1016/j.compositesb.2024.111268

捕捉多层粘合剂稳定织物的非线性材料行为并预测纤维起皱的精确成型模型

Prefabricated stacks of binder-stabilised dry fabrics are used to increase reinforcement deposition rates in the manufacturing of large composite structures such as wind turbine blades. To ensure optimal part quality, accurate simulation tools may be used to avoid costly trial-and-error experiments. This paper introduces a new modelling framework for predicting wrinkle defects that arise from forming thick binder-stabilised stacks of quasi-unidirectional non-crimp fabric. In this context, quasi-unidirectional non-crimp fabrics are unidirectional rovings stabilised with a backing layer. The non-constant bending stiffness of the fabric is modelled using an asymmetric compressive modulus, while a mixed-mode cohesive formulation with user-defined damage evolution is used for modelling the initial non-constant elastic binder interface stiffness and interface degradation. The model is verified against cantilever bending tests of single fabric layers and transverse shear experiments of bindered fabric layers. Comparison with experimental results on the forming of preforms shows that the model accurately predicts wrinkle location and geometry during the forming of thick binder-stabilised preforms. The error between the wrinkle geometry predicted by the new modelling approach and the experimentally measured wrinkle geometry is reduced by 35% to 94% compared to wrinkles predicted by conventional modelling approaches. The modelling framework is freely available at https://doi.org/10.5281/zenodo.10077428.

在风力涡轮机叶片等大型复合材料结构的制造过程中,使用预制的粘合剂稳定干织物堆栈来提高加固沉积率。为确保最佳的零件质量,可使用精确的模拟工具来避免成本高昂的试错实验。本文介绍了一种新的建模框架,用于预测准单向非卷曲织物形成厚粘合剂稳定堆叠时产生的皱褶缺陷。在这种情况下,准单向非卷曲织物是用背衬层稳定的单向粗纱。织物的非恒定弯曲刚度使用非对称压缩模量建模,而混合模式内聚公式与用户定义的损伤演变则用于建模初始非恒定弹性粘合剂界面刚度和界面退化。该模型通过单层织物的悬臂弯曲试验和双层织物的横向剪切试验进行了验证。与预型件成型实验结果的比较表明,该模型能准确预测厚粘合剂稳定预型件成型过程中的皱褶位置和几何形状。与传统建模方法预测的皱纹相比,新建模方法预测的皱纹几何形状与实验测量的皱纹几何形状之间的误差减少了 35% 至 94%。建模框架可在 https://doi.org/10.5281/zenodo.10077428 免费获取。


Composites Science and Technology

Two-step re-protonation strategy to fabricate aramid nanofiber sheet (ANFS) based high performance composite film

Yun Wei, Xin Chen, Zijian Dai, Minhan Cheng, Qiang Fu, Hua Deng

doi:10.1016/j.compscitech.2024.110480

 

用两步再质子化策略制造基于芳纶纳米纤维片(ANFS)的高性能复合薄膜

Aramid nanofibers have aroused great research enthusiasm in functional composites thanks to their numerous advantages. However, the mechanism of proton recovery in aramid nanofibers regeneration is still unclear, and the mechanical properties of aramid nanofibers, which simply and roughly regenerated from water in one-step, are still insufficient. In this work, we explore the mechanism of aramid nanofiber proton reconstruction by eight proton donor ability solvents and prepared a macroscopic sheet-like aramid nanofiber (ANFS). Studies show that weak proton donor is more likely to recover intramolecular -H-bonds, and strong proton donor is more likely to recover intermolecular -H-bonds in aramid nanofibers. Based on above, we proposed a two-step re-protonation strategy (EG + H2O) to recover aramid nanofibers structure to obtain high performance ANFS film. Furthermore, high efficiency thermal transfer channel constructed by aligned BN nanosheets along with ANFS lamellae configuration facilitate high thermal conductivity (in-plane) of 19.66 W m−1 K−1 with surprising mechanical properties with 211 MPa tensile strength, 12.8 % elongation at break, toughness of 17.94 MJ/m3 and only 10 wt% filler. This work provides a novel insight for aramid nanofibers re-protonation and high efficiency heat transfer path to obtain mechanically strong and highly thermal conductive composites.

芳纶纳米纤维以其众多优点在功能复合材料领域引起了极大的研究热情。然而,芳纶纳米纤维再生中的质子恢复机理尚不清楚,一步法简单粗暴地从水中再生出的芳纶纳米纤维的力学性能仍有不足。本研究探索了八种质子供体能力溶剂对芳纶纳米纤维质子重构的机理,制备了宏观片状芳纶纳米纤维(ANFS)。研究表明,在芳纶纳米纤维中,弱质子供体更容易恢复分子内-H键,而强质子供体更容易恢复分子间-H键。在此基础上,我们提出了两步再质子化策略(EG + H2O)来恢复芳纶纳米纤维的结构,从而获得高性能的 ANFS 薄膜。此外,由排列整齐的 BN 纳米片和 ANFS 片状结构构建的高效热传导通道可实现 19.66 W m-1 K-1 的高导热率(面内),同时还具有令人惊讶的机械性能:211 兆帕的拉伸强度、12.8 % 的断裂伸长率、17.94 MJ/m3 的韧性,而填料含量仅为 10 wt%。这项研究为芳纶纳米纤维的再质子化和高效传热路径提供了新的见解,从而获得了机械强度高、导热性强的复合材料。



来源:复合材料力学仿真Composites FEM

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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5日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 1 篇,Mechanics of Materials 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 7 篇International Journal of Solids and StructuresThe peculiar SMart-Time XB approach for delamination growth prediction and its evolution towards fatigue investigationsAngela Russo, Concetta Palumbo, Andrea Sellitto, Aniello Ricciodoi:10.1016/j.ijsolstr.2024.112681用于分层生长预测的特殊 SMart-Time XB 方法及其向疲劳研究的演变This paper deals with the Smart Time XB (SMXB) procedure, a parametric 3D methodology to simulate the delamination evolution in composite structures. The SMXB method has been developed almost ten years ago and, over time, has been improved with new features to become a forefront method compared with the state of the art. The SMXB is based on the Virtual Crack Closure Technique, which is nowadays implemented in the principal and most used Finite Elements (FE) commercial software. The main peculiarity of the SMXB is its capability to overcome the limits in terms of load step size and elements size dependences typical of the VCCT approach in mimic the delamination propagation. The SMXB procedure has been validated over years considering different structures and load conditions. The last development, which make the SMXB even more complete and attractive, is the ability to simulate the fatigue-driven delamination. Indeed, the Paris Law has been introduced in the core structure of the SMXB to make it able to mimic the delamination evolution under cyclic loading conditions. This manuscript has the intent to describe the theory behind this peculiar procedure and its evolution toward fatigue simulation. An experimental literature Double Cantilever Beam benchmark has been used to prove the robustness and effectiveness of this computational methodology, highlighting its main peculiarities. Single leg bending example, representative of a mixed mode interaction, has also been presented.本文介绍智能时间 XB(SMXB)程序,这是一种模拟复合材料结构分层演变的参数化三维方法。SMXB 方法开发于近十年前,随着时间的推移,该方法不断改进,增加了新的功能,目前已成为最先进的方法。SMXB 以虚拟裂缝闭合技术为基础,该技术目前已在主要的、最常用的有限元(FE)商业软件中实现。SMXB 的主要特点是能克服 VCCT 方法在模拟分层扩展时对载荷步长和元素尺寸相关性的限制。SMXB 程序经过多年验证,考虑了不同的结构和载荷条件。SMXB 的最后一项发展是能够模拟疲劳驱动的分层,这使得 SMXB 更加完整和具有吸引力。事实上,SMXB 的核心结构中引入了巴黎定律,使其能够模拟循环加载条件下的分层演变。本手稿旨在描述这一特殊程序背后的理论及其向疲劳模拟的演变。实验文献《双悬臂梁》基准被用来证明这种计算方法的稳健性和有效性,并强调其主要特殊性。此外,还介绍了代表混合模式相互作用的单腿弯曲示例。Mechanics of MaterialsBridged structures in ultrathin 2D materials for high toughness.Kamalendu Paul, Changjun Zhang, Chi-Hua Yu, Zhao Qindoi:10.1016/j.mechmat.2024.104932超薄二维材料中的桥式结构可实现高韧性。2D materials such as graphene, monolayer MoS2 and MXene are highly functional for their unique mechanical, thermal and electrical features and are considered building blocks for future ultrathin, flexible electronics. However, they can easily fracture from flaws or defects and thus it is important to increase their toughness in applications. Here, inspired by natural layered composites and architected 3D printed materials of high toughness, we introduce architected defects to the 2D materials and study their fracture in molecular dynamics simulations. We find that the length of the defects in the shape of parallel bridges is crucial to fracture toughness, as long bridges can significantly increase the toughness of graphene and MoS2 but decrease the toughness of MXene, while short bridges show opposite effects. This strategy can increase the toughness of 2D materials without introducing foreign materials or altering the chemistry of the materials, providing a general method to improve their mechanics.二维材料(如石墨烯、单层 MoS2 和 MXene)因其独特的机械、热和电特性而具有很高的功能性,被认为是未来超薄柔性电子器件的基石。然而,它们很容易因缺陷或瑕疵而断裂,因此在应用中提高其韧性非常重要。在此,受天然层状复合材料和具有高韧性的结构化 3D 打印材料的启发,我们在二维材料中引入了结构化缺陷,并在分子动力学模拟中研究了它们的断裂情况。我们发现,平行桥形状的缺陷长度对断裂韧性至关重要,因为长桥可显著提高石墨烯和 MoS2 的韧性,但会降低 MXene 的韧性,而短桥则显示出相反的效果。这种策略可以在不引入外来材料或改变材料化学性质的情况下提高二维材料的韧性,为改善二维材料的力学性能提供了一种通用方法。International Journal of PlasticityNew deformation mechanism and strength-ductility synergy in pure titanium with high density twinS.Z. Wang, Z.H. Hu, Z.W. Huang, B. Gao, X.F. Chen, J.J. Hu, Y.T. Zhu, Y.S. Li, H. Zhoudoi:10.1016/j.ijplas.2024.103908高密度孪晶纯钛的新变形机制和强度-电导率协同作用The simultaneous optimization of strength and ductility in high-performance metallic materials has long been a challenge for researchers, characterized by an inherent trade-off between the two properties. Despite a vast body of research aimed at overcoming this challenge, achieving a desirable balance between strength and ductility remains elusive. Here, we present a novel approach that involves the introduction of high-density twin boundaries into pure Ti while maintaining a nearly unchanged grain size. This approach leads to a significant improvement in yield strength, ultimate tensile strength, and uniform elongation of pure Ti. In-situ electron backscatter diffraction (EBSD) analysis reveals a substantially higher density of dislocations in twins compared to the matrix, which translates into a remarkable improvement in strain hardening rate and enhanced ductility at high stress levels. The finding from the In-Grain Misorientation Axes (IGMA) distribution method indicate that the high density of dislocations is triggered by the activation of non-basal <c+a> slipping. Furthermore, it is reveaaled that, in addition to the preferred crystal orientations and potential dislocation transmutation mechanisms, an increase in the c/a ratio near the twin boundaries also contributes to the activation of <c+a> dislocations within twins. Our findings offer a promising route for developing high-performance HCP (Hexagonal close-packed) metallic alloys by introducing high-density twins.长期以来,如何同时优化高性能金属材料的强度和延展性一直是研究人员面临的一项挑战,因为这两种性能之间存在固有的权衡。尽管有大量的研究旨在克服这一挑战,但要在强度和延展性之间实现理想的平衡仍然难以实现。在此,我们提出了一种新方法,即在纯钛中引入高密度孪晶边界,同时保持几乎不变的晶粒尺寸。这种方法显著提高了纯钛的屈服强度、极限拉伸强度和均匀伸长率。原位电子反向散射衍射(EBSD)分析表明,与基体相比,孪晶中的位错密度要高得多,从而显著提高了应变硬化率,并增强了高应力水平下的延展性。晶内偏斜轴(IGMA)分布方法的研究结果表明,高密度位错是由非基体<c+a>滑动激活引起的。此外,研究还揭示出,除了优选晶体取向和潜在的位错嬗变机制外,孪晶边界附近的 c/a 比值增加也有助于激活孪晶内部的 <c+a> 位错。我们的研究结果为通过引入高密度孪晶开发高性能 HCP(六方紧密堆积)金属合金提供了一条前景广阔的途径。Thin-Walled StructuresMechanical characteristic and stress-strain modelling of friction stir welded 6061-T6 aluminium alloy butt jointsBeibei Li, Pengcheng He, Jingfeng Wang, Xuebei Pan, Yuanqing Wang, Zhongxing Wang, Charalampos C. Baniotopoulosdoi:10.1016/j.tws.2024.111645搅拌摩擦焊接 6061-T6 铝合金对接接头的机械特性和应力应变模型This paper investigates the mechanical properties and softening extent of friction stir welded (FSW) 6061-T6 aluminium alloy butt joints through experimental studies and theoretical analyses. A total of 138 monotonic tensile coupon tests and 46 Vickers hardness tests, cut from 5-, 8-, 12, 16-mm-thick welded plates using various welding speed, tool rotation speed and tool configurations, were systematically performed. The surface morphology after welding, failure modes, stress-strain curves and hardness distribution laws were evaluated. An assessment of the applicability of existing constitutive model and proposed model to FSW aluminium alloys were presented, with predictive equations for the key input parameters further derived. The results show that the strength reduction and softening extent induced by FSW under the optimal welding parameters were superior to those of 6061-T6 aluminium alloy plates joined by fusion welding process in accordance with Chinese and European standards, indicating the effectiveness and applicability in aluminium alloy component forming and structural connections using FSW technology. The stress-strain curves of FSW butt joints exhibited higher strain hardening effect but lower ductility. The developed three-stage Ramberg-Osgood model, using seven known key input parameters, was shown to provide a very high accurate and consistent predictions in full-range stress-strain curves in comparison with existing constitutive models. Moreover, the proposed constitutive model, using only three common available parameters, could still achieve a great balance between accuracy and practicality.本文通过实验研究和理论分析,探讨了搅拌摩擦焊接(FSW)6061-T6 铝合金对接接头的机械性能和软化程度。在不同的焊接速度、工具旋转速度和工具配置下,对 5、8、12 和 16 毫米厚的焊接板材进行了 138 次单调拉伸试样测试和 46 次维氏硬度测试。对焊接后的表面形态、失效模式、应力-应变曲线和硬度分布规律进行了评估。评估了现有构成模型和建议模型对 FSW 铝合金的适用性,并进一步得出了关键输入参数的预测方程。结果表明,在最佳焊接参数下,FSW 所引起的强度降低和软化程度均优于采用熔化焊接工艺连接的 6061-T6 铝合金板材,符合中国和欧洲标准,表明了采用 FSW 技术在铝合金部件成形和结构连接中的有效性和适用性。FSW 对接接头的应力-应变曲线表现出较高的应变硬化效应,但延展性较低。所开发的三阶段 Ramberg-Osgood 模型使用了七个已知的关键输入参数,与现有的构成模型相比,该模型可提供非常准确和一致的全范围应力应变曲线预测。此外,所提出的构成模型只使用了三个常见的可用参数,仍能在准确性和实用性之间取得很好的平衡。Macroscopic and Mesoscopic Simulation of Damage Behavior for CF/BMI Laminates Induced by Rectangular Cross-sectional TC4 Flyer High-speed ImpactEnling Tang, Wei Zhang, Xinxin Wang, Lei Li, Hui Peng, Chuang Chen, Yafei Han, Mengzhou Chang, Kai Guo, Liping Hedoi:10.1016/j.tws.2024.111675矩形截面 TC4 飞碟高速撞击诱发 CF/BMI 层压板损伤行为的宏观和介观模拟In this paper based on the turbofan engine fan casing, the rectangular cross-section TC4 flyer high-speed impact carbon fiber/bismaleimide (CF/BMI) composite laminate was used to simulate the impact of failed blade fragments on the casing. Based on mechanical properties tests and equivalent mechanics theory, the mechanical properties parameters of laminates were obtained. The mesoscopic CF/BMI laminates model was built by TexGen. The Hashin failure criterion was implanted into the VUMAT subroutine. ABAQUS/Explicit was used to simulate the normal penetration and oblique penetration of ballistic impact experiments to obtain the strain time history curves, macroscopic damage process and mesoscopic damage morphology. The reliability of the numerical simulation method was verified by ballistic impact test. On this basis, the mechanical response and impact damage characteristics of flyer penetrating CF/BMI laminates under different impact velocities (260m/s, 300m/s), incident angles (45°, 60°, 90°) and flyer flight attitudes were studied. The damage characteristics of CF/BMI laminates under high-speed impact of flyer were obtained by combining the dynamic response analysis of two components of carbon fiber layer and bismaleimide resin in the laminates.本文以涡扇发动机风扇壳体为基础,采用矩形截面 TC4 飞翼高速冲击碳纤维/双马来酰亚胺(CF/BMI)复合材料层压板来模拟失效叶片碎片对壳体的冲击。根据力学性能测试和等效力学理论,获得了层压材料的力学性能参数。利用 TexGen 建立了中观 CF/BMI 层压板模型,并在 VUMAT 子程序中植入了 Hashin 失效准则。使用 ABAQUS/Explicit 对弹道冲击实验中的法向穿透和斜向穿透进行模拟,以获得应变时间历程曲线、宏观损伤过程和中观损伤形态。弹道冲击试验验证了数值模拟方法的可靠性。在此基础上,研究了不同冲击速度(260m/s、300m/s)、入射角度(45°、60°、90°)和飞行姿态下飞弹穿透 CF/BMI 层压板的力学响应和冲击损伤特征。通过对层压板中的碳纤维层和双马来酰亚胺树脂两部分的动态响应分析,得出了 CF/BMI 层压板在飞行器高速撞击下的损伤特征。Experimental and numerical investigations of Frameless CFSCW under combined in-plane shear and axial loadsS. Vaze, T.Y. Yang, F. Bagatini-Cachuço, X. Pandoi:10.1016/j.tws.2024.111677无框架 CFSCW 在面内剪切和轴向联合载荷作用下的实验和数值研究This paper presents a comprehensive evaluation of a novel Cold Form Steel Corrugated Walls (CFSCWs), named Frameless CFSCWs, under combined axial and lateral loads. A series of experimental investigations were carried out on full-scale specimens. The influence of different axial loads on the buckling-failure mode, the peak force capacity, the post-buckling stiffness, and the residual force capacity are presented. Subsequently, robust finite element models were developed to simulate the complex bucking behavior of these Frameless CFSCWs. The results of the experimental and numerical investigations revealed that the lateral force-deformation response of Frameless CFSCW is highly influenced by the axial loads. A linearized backbone curve of the Frameless CFSCWs with different axial loads is proposed. Key design parameters such as overstrength and ductility ratios of the Frameless CFSCW panels are identified. The linearized backbone curve can be used by engineer to design Frameless CFSCWs under different axial loads.本文介绍了在轴向和侧向荷载共同作用下对新型冷弯钢筋波形墙(CFSCWs)(无框架 CFSCWs)的综合评估。在全尺寸试件上进行了一系列实验研究。实验研究了不同轴向载荷对屈曲破坏模式、峰值受力能力、屈曲后刚度和残余受力能力的影响。随后,建立了稳健的有限元模型来模拟这些无框架 CFSCW 的复杂屈曲行为。实验和数值研究结果表明,无框架 CFSCW 的侧向力-变形响应受轴向载荷的影响很大。提出了不同轴向载荷下无框架 CFSCW 的线性化骨架曲线。确定了无框架 CFSCW 面板的超强度和延性比等关键设计参数。工程师可利用线性化骨架曲线设计不同轴向载荷下的无框 CFSCW 板。Thermal-mechanical coupling analysis of membrane surface failure of the air-supported membrane structure under fire considering weld seamsYaning Zhang, Ying Sun, Qiming Zhu, Zhenggang Cao, Yang Yudoi:10.1016/j.tws.2024.111678考虑焊缝的火灾条件下空气支撑膜结构膜面失效的热力学耦合分析The membrane surface failure by developing a tear in air-supported membrane structures under fire conditions affects the deflation and collapse of the structure. However, in most existing studies, the failure is evaluated only according to whether the membrane surface temperature reaches the burn-through temperature of the membrane materials, without considering the effect of internal pressure variation caused by fire, and there have been even few studies on the impact of weld seams on membrane surface. This paper introduces the simplified constitutive models for PVC membranes and weld seams and a numerical simulation method to analyze the stress on the membrane surface of air-supported membrane structures during fire, taking into consideration the coupling effect of high temperature and internal pressure change. Numerical responses and the results of the full-scale fire test case by HIT (Harbin Institute of Technology) team are compared to demonstrate the effectiveness and applicability of the proposed material models and the simulation method. The study shows that the weld seams are the weak parts of the membrane surface under fire. The membrane surface failure may not first occur at the maximum temperature point of the membrane surface and the initial failure temperature is much less than the burn-through temperature of the membrane materials. Moreover, the initial failure of membrane surface should be attributed to the coevolutionary results of the stress field on the membrane surface and the degraded material properties at elevated temperatures. If the temperature is the only index to determine membrane surface failure in the air-supported membrane structure under fire, the common reference failure temperature should be reduced (approximately 120 ℃ for weld seams and 140 ℃ for membranes). The present study is valuable for fire risk assessment, performance-based fire protection design, and coupled analysis of fire and wind disasters in membrane structures.在火灾条件下,空气支撑膜结构的膜表面会因撕裂而失效,从而影响结构的放气和坍塌。然而,在现有的大多数研究中,仅根据膜表面温度是否达到膜材料的烧穿温度来评估其失效,而没有考虑火灾引起的内部压力变化的影响,甚至很少有关于焊缝对膜表面影响的研究。考虑到高温和内压变化的耦合效应,本文介绍了 PVC 膜材和焊缝的简化构成模型以及数值模拟方法,以分析火灾时空气支撑膜结构膜材表面的应力。通过比较数值响应和哈尔滨工业大学团队的全尺寸火灾试验结果,证明了所提出的材料模型和模拟方法的有效性和适用性。研究表明,焊缝是膜表面在火灾中的薄弱部位。膜表面失效可能不会首先发生在膜表面的最高温度点,初始失效温度远低于膜材料的烧穿温度。此外,膜表面的初始失效应归因于膜表面应力场和高温下材料性能退化的共同演变结果。如果将温度作为火灾条件下空气支撑膜结构膜表面失效的唯一指标,则应降低常见的参考失效温度(焊缝约为 120 ℃,膜材料约为 140 ℃)。本研究对火灾风险评估、基于性能的防火设计以及膜结构火灾和风灾耦合分析具有重要价值。Mesoscopic statistics-based probability characteristics of chloride transport and reliability-based corrosion initiation life of bridge towerDingshi Chen, Wenhua Guo, Xiankai Quan, Binxin Duan, Liujun Guodoi:10.1016/j.tws.2024.111680基于介观统计的氯离子迁移概率特征和基于可靠性的桥塔腐蚀起始寿命Chloride-induced corrosion involves multiple factors and uncertainties. This study focuses on the probabilistic and multifactorial prediction model for the reliability and service life of reinforced concrete structures in marine environments. We present a new probabilistic framework to quantify the uncertainty of chloride transport by mesoscopic statistics and Spearman correlation analysis and develop a modified chloride transport model, incorporating multi-factors such as time dependence, admixture usage, temperature, relative humidity, stress level, freeze-thaw cycles, chloride binding capacity, aggregate volume fraction, aggregate particle size, and concrete deterioration. Taking the Shenzhen-Zhongshan Bridge as an example, by considering the chloride diffusion coefficient, concrete cover thickness, convection zone thickness, critical chloride concentration, and surface chloride concentration as random variables, the first-order reliability method (FORM) was employed to determine the time-variant reliability index and service life of the example bridge in different environmental conditions, encompassing atmospheric, splashing, tidal, and submerged zones. The sensitivity of the time-variant reliability to these random variables and the impact of the non-random variables on the reliability index were investigated quantitatively and comparatively. The findings reveal significant temporal and spatial variability in chloride diffusion coefficients due to the random arrangement of aggregates within concrete. The study demonstrates that concrete cover thickness and chloride diffusion coefficient are the most influential variables on structural reliability and emphasizes the substantial impact of admixtures, concrete deterioration, and environmental factors on the time-variant reliability. This research offers a significant reference in the reliability design, safety assessment, and maintenance of concrete structures in chloride-rich environments.氯化物引起的腐蚀涉及多种因素和不确定性。本研究重点关注海洋环境中钢筋混凝土结构可靠性和使用寿命的概率和多因素预测模型。我们提出了一个新的概率框架,通过中观统计和斯皮尔曼相关分析来量化氯离子迁移的不确定性,并建立了一个改进的氯离子迁移模型,将时间依赖性、外加剂用量、温度、相对湿度、应力水平、冻融循环、氯离子结合能力、骨料体积分数、骨料粒径和混凝土劣化等多因素纳入其中。以深圳-中山大桥为例,将氯离子扩散系数、混凝土覆盖层厚度、对流区厚度、临界氯离子浓度和表面氯离子浓度视为随机变量,采用一阶可靠度法(FORM)确定了示例桥梁在不同环境条件下的时变可靠度指数和使用寿命,包括大气区、溅水区、潮汐区和水下区。定量和比较研究了时变可靠性对这些随机变量的敏感性以及非随机变量对可靠性指数的影响。研究结果表明,由于混凝土中集料的随机排列,氯化物扩散系数在时间和空间上都存在很大的差异。研究表明,混凝土覆盖层厚度和氯化物扩散系数是对结构可靠性影响最大的变量,并强调了外加剂、混凝土老化和环境因素对时变可靠性的重大影响。这项研究为富含氯化物环境中混凝土结构的可靠性设计、安全评估和维护提供了重要参考。Flexural performance of high strength grouted SHS tube-sleeve connection for modular constructionZhenyu HUANG, Xiaolong ZHAO, Weixiong DENG, Wei ZHANG, Tao LI, Zhiqiang ZHONGdoi:10.1016/j.tws.2024.111653模块化建筑中高强度灌浆 SHS 管-套筒连接的挠曲性能Prefabricated prefinished volumetric construction divides traditional buildings into room-sized modules that are manufactured off-site and assembled on-site. This construction method offers improved construction speed, superior quality control, and reduced environmental impact compared to traditional construction. In high-rise modular construction, the connections between modules may experience significant bending moments due to wind loads or earthquakes. Therefore, the flexural performance of these connections becomes a critical factor that affects the overall stability and robustness of the modular structures. The present study combines the advantages of high strength grout and square hollow section tube sleeves to develop a robust grouted connection for prefabricated structures without compromising assembly efficiency. Firstly, the study conducts three-point bending tests on eight full-scale specimens to investigate the flexural behavior of the connection. The load transfer mechanism, failure modes, moment-curvature relationship, and strain development of the tube-sleeve connection under lateral load are analyzed in detail. The study also quantifies and discusses the effects of different shear key spacing, grout length, inner tube width, and steel fiber content on the strength and stiffness of the connection. In addition, the study utilizes ABAQUS to simulate the bending responses of the connection, including inner tube fracture, grout crack development, and internal complex strain state. The finite element analysis results demonstrate good agreement with the experimental results, with an average ratio of 1.04 between numerical results and test results for flexural resistance, and a standard deviation of 0.04. Furthermore, based on elasto-plastic mechanics and the actual cross-sectional stress distribution of the connection, three analytical models are proposed to predict the flexural resistance of the connection. Finally, the moment-shear interaction relation is verified against the finite element and test results using the elastic-plastic analytical model and the ultimate state shear model.预制预成品体积建筑将传统建筑分成房间大小的模块,这些模块在场外生产,然后在现场组装。与传统建筑相比,这种施工方法提高了施工速度,加强了质量控制,并减少了对环境的影响。在高层模块化建筑中,由于风荷载或地震的影响,模块之间的连接可能会承受很大的弯矩。因此,这些连接件的抗弯性能成为影响模块化结构整体稳定性和坚固性的关键因素。本研究结合了高强度灌浆料和方形空心截面管套筒的优势,在不影响装配效率的前提下,为预制结构开发了一种坚固的灌浆连接。首先,本研究对八个全尺寸试件进行了三点弯曲试验,以研究该连接的抗弯行为。详细分析了管套连接在横向荷载作用下的荷载传递机制、破坏模式、弯矩-曲率关系和应变发展。研究还量化并讨论了不同剪力键间距、灌浆长度、内管宽度和钢纤维含量对连接强度和刚度的影响。此外,研究还利用 ABAQUS 模拟了连接的弯曲响应,包括内管断裂、灌浆裂缝发展和内部复杂应变状态。有限元分析结果表明与实验结果非常吻合,抗弯数值结果与测试结果的平均比率为 1.04,标准偏差为 0.04。此外,根据弹塑性力学和连接的实际截面应力分布,提出了三个分析模型来预测连接的抗弯强度。最后,利用弹塑性分析模型和极限状态剪切模型,根据有限元和测试结果验证了力矩-剪切相互作用关系。A hybrid operator-based multifactorial evolutionary algorithm for inverse-engineering design of soft network materialsSunze Cao, Xiao Feng, Jiahui Chang, Yongbin Yu, Xiangxiang Wang, Jingye Cai, Yuchen Lai, Hao Wangdoi:10.1016/j.tws.2024.111655基于混合算子的多因素进化算法,用于软网络材料的逆工程设计Soft network materials (SNMs) are a class of network materials with periodic thin curved filaments in lattice patterns, offering excellent physical properties of high stretchability, highly tunable mechanical properties, and lightweight. Several theoretical models have been established for the inverse-engineering design of SNMs for reproducing the nonlinear J-shaped stress–strain curves for mechanical bionics. However, the existing design models required the semi-subjective decision in the choice of key geometric parameters, critical strain, etc., under the limited material libraries. In this study, we developed a brand-new hybrid operators-based multifactorial evolutionary algorithm (HOMFEA) for the inverse-engineering design of SNMs to reproduce the J-shaped stress–strain curves of various target soft biological tissues. The core algorithms in HOMFEA include a hybrid operator proposed based on the memetic algorithm theory, a vertical cultural transmission, and population formation coupled with modeling methods for SNMs. The HOMFEA-based design strategy allows more accurate reproduction of target stress–strain curves compared to the conventional EA-based framework and a phenomenological-based mechanical model. The high-performance computing capability suggests that it can serve as a reliable tool for more inverse-engineering design scenarios.软网络材料(SNMs)是一类具有周期性弯曲细丝晶格图案的网络材料,具有高拉伸性、高可调机械性能和轻质等优异的物理特性。目前已建立了多个反工程设计 SNM 的理论模型,用于再现机械仿生学的非线性 J 型应力-应变曲线。然而,现有的设计模型需要在有限的材料库条件下半主观地选择关键几何参数、临界应变等。在本研究中,我们开发了一种全新的基于算子的混合多因素进化算法(HOMFEA),用于 SNM 的逆工程设计,以重现各种目标软生物组织的 J 型应力应变曲线。HOMFEA 的核心算法包括基于记忆算法理论提出的混合算子、垂直文化传播、种群形成以及 SNM 建模方法。与传统的基于 EA 的框架和基于现象学的力学模型相比,基于 HOMFEA 的设计策略能更准确地再现目标应力-应变曲线。高性能计算能力表明,它可以作为一种可靠的工具,用于更多的逆工程设计方案。来源:复合材料力学仿真Composites FEM

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