今日更新：Composite Structures 4 篇，Composites Part A: Applied Science and Manufacturing 1 篇，Composites Part B: Engineering 1 篇，Composites Science and Technology 1 篇Composite StructuresMulti-scale concurrent topology optimization of cellular structures with multiple microstructures for minimizing dynamic response in the time domainJian Wang, Yan Zhang, Xiaoyu Wang, Xuyang Zheng, Zhiyong Ma, Wei-Hsin Liao, Nan Zhu, Qiang Gaodoi:10.1016/j.compstruct.2024.118124多微结构元胞结构的多尺度并行拓扑优化，以实现时域动态响应最小化This paper proposes a concurrent topology optimization method for optimizing the structures that are periodically filled with multiple microstructures excited by dynamic response in the time domain. At the macroscale, different microstructures are considered as different materials. To generate the various distribution of different microstructures, a multi-material interpolation approach based on the Solid Isotropic Material with Penalization (SIMP) is integrated. At the microscale, the energy-based homogenization method (EBHM) is employed to determine the macroscopic effective properties of the microstructures. All macroscale elements with identical material are represented by a distinct microstructure. For the proportional damping model, the HHT-α is implemented as a time integration technique to obtain the dynamic response of multi-scale and assumed multi-material structures. The objective function of the topology optimization problem is to minimize the mean dynamic compliance. Combined differentiate-then-discretize method with the adjoint variable method, the sensitivity analysis applies the gradient-based Zhang-Paulino-Ramos Jr. (ZPR) algorithm or Method of Moving Asymptotes (MMA) to update the design variables under multiple constraints in the time and space-discretized system. The proposed approach is numerically performed through 2D and 3D examples to demonstrate its effectiveness.本文提出了一种并行拓扑优化方法，用于在时域动态响应激励下周期性填充多个微结构的结构优化。在宏观尺度上，不同的微观结构被认为是不同的材料。为了生成不同微观结构的不同分布，提出了一种基于固体各向同性材料惩罚(SIMP)的多材料插值方法。在微观尺度上，采用基于能量的均匀化方法(EBHM)来确定微观结构的宏观有效性质。所有具有相同材料的宏观元素都具有不同的微观结构。对于比例阻尼模型，HHT-α作为时间积分技术实现了多尺度和假设多材料结构的动态响应。拓扑优化问题的目标函数是使平均动态柔度最小。灵敏度分析将微分-离散化方法与伴随变量法相结合，采用基于梯度的Zhang-Paulino-Ramos Jr. (ZPR)算法或移动渐近线法(MMA)对时空离散化系统中多约束条件下的设计变量进行更新。通过二维和三维算例验证了该方法的有效性。A generic design motif for metamaterials with controllable nonlinearity & guided deformationXiaofeng Geng, Zhipeng Zhao, Yingqing Guo, Jiqiang Wang, Hu Ding, Xingjian Jingdoi:10.1016/j.compstruct.2024.118125具有可控非线性和导向变形的超材料的通用设计母题Structure design motifs take an essential role in creating materials or metamaterials with superior mechanics or special functions. However, a fundamental question naturally arising and remaining unknown is related to how to effectively design an engineered material structure with “adjustable and predictable” nonlinear mechanic properties conveniently. Here we propose a very simple but versatile design motif, named as bq-structure, which can provide superior flexibility in achieving various nonlinear properties, including 200 % larger and designable ranges of quasi-zero stiffness, negative stiffness, and multi-stable stiffness, etc, that original material or traditional beam-based design motifs cannot provide. The proposed design motif has sufficient reliability in nonlinear manipulation with a “guided & controllable” manner instead of “trail-and-error attempts” existing in most existing ones. A prototyped vibration isolation unit can achieve a resonant frequency less than 1 Hz easily which cannot be done with many other methods of similar size and payload. Given the large elastic deforming capacity and ductility in structural scale, the superb nonlinearity regime is generally designable with various structure parameters, uniquely providing a superior optimization tool with this novel design motif considering various real application requirements for advanced materials design, energy storage or conversion, mechanical vibration mitigation, and robotic systems etc结构设计图案在创造具有优越力学或特殊功能的材料或超材料方面起着至关重要的作用。然而，如何有效地、方便地设计具有“可调可预测”非线性力学性能的工程材料结构，是一个自然产生而又未知的基本问题。在这里，我们提出了一个非常简单但通用的设计母题，称为bq结构，它可以提供优越的灵活性，以实现各种非线性特性，包括200 %的可设计范围的准零刚度，负刚度和多稳定刚度等，这是原始材料或传统的基于梁的设计母题所不能提供的。本文提出的设计母题在非线性操作中具有足够的可靠性，具有“引导可控”的方式，而不是大多数现有设计母题存在的“跟踪-错误尝试”。原型隔振单元可以轻松实现小于1 Hz的谐振频率，这是许多其他类似尺寸和有效载荷的方法无法实现的。由于具有较大的弹性变形能力和结构尺度上的延展性，其优异的非线性体系通常可设计为各种结构参数，独特地为先进材料设计、能量存储或转换、机械振动缓解和机器人系统等各种实际应用需求提供了优越的优化工具Fatigue and post-fatigue behavior of FRCM-concrete specimens under direct shear and bending conditionsAngelo Savio Calabrese, Pierluigi Colombi, Tommaso D'Antinodoi:10.1016/j.compstruct.2024.118129直接剪切和弯曲条件下frcm -混凝土试件的疲劳及后疲劳行为The combined effect of cyclic loading and steel rebar corrosion can determine the premature deterioration of reinforced concrete (RC) structures subjected to dynamic and environmental actions. The use of fabric-reinforced cementitious matrix composites (FRCM) is a promising solution to extend the fatigue life of RC structures. Externally bonded FRCMs are applied to the tension side of structural members to reduce the rebar stress level, thus delaying fatigue crack nucleation and/or propagation. A key aspect for the design of FRCM strengthening of these structures is the matrix-fiber bond behavior under fatigue loading. In this paper, a critical review of currently available studies on the fatigue behavior of FRCM-strengthened RC beams is presented. Then, the results of 25 bond tests on PBO FRCM-concrete specimens are provided and discussed. These tests include both single-lap direct shear and modified beam tests performed in quasi-static and cyclic mode. The results obtained show that the cyclic load may induce progressive debonding at the matrix-fiber interface with rupture of fiber filaments. Modified beam tests are more affected by these phenomena than direct shear tests. The rupture of fiber filaments is confirmed by the results of post-fatigue tests that show capacities lower than those of corresponding quasi-static tests.循环荷载和钢筋腐蚀的共同作用可以决定钢筋混凝土结构在动力和环境作用下的过早劣化。纤维增强胶凝基复合材料(FRCM)是延长钢筋混凝土结构疲劳寿命的一种很有前途的方法。外粘结frp材料应用于构件受拉侧，以降低钢筋应力水平，从而延缓疲劳裂纹的形核和/或扩展。疲劳载荷下的基体-纤维粘结性能是frp加固设计的一个关键方面。本文对目前已有的frp增强RC梁疲劳性能研究进行了综述。给出了PBO frp -混凝土试件25次粘结试验结果并进行了讨论。这些试验包括在准静态和循环模式下进行的单搭接直剪和修改梁试验。结果表明:循环荷载可引起纤维-基体界面的渐进式剥离，纤维细丝断裂。修正梁试验比直接剪切试验受这些现象的影响更大。疲劳后试验结果证实了纤维长丝的断裂，其承载力低于相应的准静态试验结果。Experimental and numerical analysis of low-velocity impact and compression after impact responses of novel 3D hybrid compositesKe Wang, Farid Taheridoi:10.1016/j.compstruct.2024.118133新型三维混杂复合材料低速冲击和冲击后压缩响应的实验与数值分析Rising environmental concerns and the push to cut carbon emissions have resulted in increased incorporation of lightweight materials to improve fuel efficiency across industries. Fiber Metal Laminates (FMLs), known for superior properties, are widely used in aerospace. In the same vein, the recently developed 3D Fiber-Metal Laminates (3DFMLs) with a 3D composite core have been demonstrated to offer remarkable performance despite fabrication challenges.Two innovative 3D hybrid composites (3DFML-PI and 3DHC-PI) are introduced. These FMLs integrate plastic inserts to overcome the fabrication hurdles experienced by the original 3DFMLs and enhance their mechanical properties. Notably, 3DFML-PI shows comparatively an exceptional impact resistance with a higher perforation threshold, highlighting the efficacy of plastic inserts. Additionally, 3DFML-PI exhibits higher compressive strength, suggesting improved consolidation of the 3D composites. Comparison of the compression-after-impact (CAI) performances also underscores the advantages of high flexural stiffness and localized damage. The research justifies further exploration and implementation of these innovative materials in practical applications requiring lightweight materials with high specific strength, stiffness, impact resistance, and economic sustainability.日益严重的环境问题和减少碳排放的努力，导致各行各业越来越多地采用轻质材料，以提高燃油效率。金属纤维层压板(FMLs)以其优越的性能被广泛应用于航空航天领域。同样，最近开发的3D纤维-金属层压板(3DFMLs)具有3D复合材料核心，尽管在制造方面存在挑战，但已被证明具有卓越的性能。介绍了两种新型的三维复合材料3DFML-PI和3DHC-PI。这些FMLs集成了塑料插入件，克服了原始3DFMLs的制造障碍，提高了其机械性能。值得注意的是，3DFML-PI具有相对优异的抗冲击性，具有较高的穿孔阈值，突出了塑料镶件的有效性。此外，3DFML-PI具有更高的抗压强度，表明3D复合材料的固结得到改善。冲击后压缩(CAI)性能的比较也强调了高抗弯刚度和局部损伤的优势。这项研究证明了这些创新材料在实际应用中的进一步探索和实施，这些材料需要具有高比强度、刚度、抗冲击性和经济可持续性的轻质材料。Composites Part A: Applied Science and ManufacturingUncut fiber analysis using fiber deflection and cutting forces in carbon fiber-reinforced plastics during rotation of the cutting toolDong-Gyu Kim, Seung-Han Yangdoi:10.1016/j.compositesa.2024.108206利用切削刀具旋转过程中碳纤维增强塑料的纤维挠度和切削力对未切削纤维进行分析Cutting, milling, and drilling during the manufacture of carbon fiber-reinforced plastics (CFRPs) is an active field of research. It is challenging to analyze cutting characteristics during cutting tool rotation because the chip thickness, fiber cutting angle, and specific cutting force change. Here, we used a mechanical model to study the cutting forces and fiber deflections that develop as the cutting tool rotates during CFRP milling. The fiber and matrix were modeled as a beam, and the cutting force and fiber deflection were analyzed according to the fiber cutting angle. We explored how uncut fiber status and surface roughness were affected. If the fiber deflection caused by transverse cutting forces was not eliminated before the cutting tool rotation angle attained 180°, some fibers were not cut. Serious defects developed when uncut fibers were not generated at certain fiber orientation angles.碳纤维增强塑料(CFRPs)制造过程中的切削、铣削和钻孔是一个活跃的研究领域。由于切屑厚度、纤维切削角度和切削比力的变化，刀具旋转过程中的切削特性分析具有一定的挑战性。在这里，我们使用力学模型来研究CFRP铣削过程中刀具旋转时产生的切削力和纤维挠度。将纤维和基体建模为一根梁，根据纤维切割角度分析了切割力和纤维挠度。我们探索了未切割的纤维状态和表面粗糙度是如何受到影响的。如果在刀具旋转角度达到180°之前没有消除横向切削力引起的纤维挠曲，则部分纤维未被切割。在一定的纤维取向角度下，未切割的纤维产生时，会产生严重的缺陷。Composites Part B: EngineeringBamboo as a natural optimized fiber reinforced composite: interfacial mechanical properties and failure mechanismsXiaohan Chen, Xianke Wang, Xun Luo, Lin Chen, Yuquan Li, Jiarui Xu, Zengqian Liu, Chunping Dai, Hu Miao, Huanrong Liudoi:10.1016/j.compositesb.2024.111458竹作为一种天然优化纤维增强复合材料:界面力学性能及破坏机制Bamboo is a typical natural fiber-reinforced composite with an optimized distribution of vascular bundles as reinforcement and parenchyma tissues as bio-matrix. The interfacial bonding performance between vascular bundles and parenchyma tissue is critical for the mechanical properties and failure mechanisms of bamboo. This study employed pull-out tests to determine the interfacial shear strength (IFSS) between bamboo vascular bundles and parenchyma tissue and evaluate the critical embedded lengths () of vascular bundles. The effects of embedded vascular bundle lengths on interfacial strength and failure behaviors were also investigated. The results revealed a value of 2.51 mm, lower than the majority of plant fiber-reinforced composite materials, with an IFSS of around 20 MPa, surpassing most artificial bamboo fiber composites. The pull-out process of the vascular bundles involved elasticity, debonding, and sliding friction stage, where debonding energy absorption (DEA) outweighed frictional energy absorption (FEA) and increasing with embedded length. The primary failure features include interfacial debonding, parenchyma tissue ripping, delamination of fiber thin layers, and fiber breakage. Moreover, the parenchyma cells between the two fiber sheaths and at the top of the bamboo block readily detached. The interfacial failure mechanisms of bamboo included debonding, reinforcement, and matrix failure, with the proportions varying as the embedded length increased. Quantitative analysis of the interfaces structure and mechanical properties between vascular bundles and parenchyma tissues could provide a reference for the biomimicry of bamboo structures and the manufacturing of natural fiber-reinforced composite materials.竹是一种典型的天然纤维增强复合材料，以维管束为增强材料，以薄壁组织为生物基质。维管束与薄壁组织之间的界面结合性能对竹材的力学性能和破坏机制至关重要。本研究采用拔除试验测定了竹材维管束与薄壁组织的界面剪切强度(IFSS)，并评估了维管束的临界嵌入长度()。研究了嵌入维管束长度对界面强度和破坏行为的影响。结果表明，IFSS值为2.51 mm，低于大多数植物纤维增强复合材料，IFSS约为20 MPa，超过大多数人造竹纤维复合材料。维管束的拔出过程分为弹性阶段、脱粘阶段和滑动摩擦阶段，其中脱粘能量吸收(DEA)大于摩擦能量吸收(FEA)，且随着埋置长度的增加而增加。主要的破坏特征包括界面脱粘、薄壁组织撕裂、纤维薄层脱层和纤维断裂。此外，两种纤维鞘之间和竹块顶部的薄壁细胞容易脱落。竹材界面破坏机制主要有脱粘破坏、加固破坏和基体破坏，其破坏比例随埋置长度的增加而变化。定量分析竹材维管束与薄壁组织之间的界面结构和力学性能，可为竹材结构的仿生学和天然纤维增强复合材料的制造提供参考。Composites Science and TechnologyA novel strategy to prepare rubber/clay nanocomposites via compounding clay gel into cocoamidopropyl betaine modified styrene butadiene rubberZilong Chen, Jian Li, Zhanxu Li, Jun Lin, Liqun Zhang, Shaojian Hedoi:10.1016/j.compscitech.2024.110602 将粘土凝胶复配至椰酰胺丙基甜菜碱改性丁苯橡胶中制备橡胶/粘土纳米复合材料的新策略In this study, high performance styrene-butadiene rubber (SBR)/clay nanocomposites (NCs) modified by cocoamidopropyl betaine (CAPB) are prepared via an efficient and facile strategy. CAPB-modified SBR was compounded with clay gel via gel compounding method to obtain SBR/clay composites. The effect of processing condition and CAPB on the mechanical properties of the SBR/clay composites was investigated. XRD and TEM results show that clay dispersion in SBR matrix is significantly improved due to the success of CAPB in the hydrophilic modification of SBR. The clay-SBR interaction is enhanced and more SBR molecular chains are adsorbed to the clay, significantly improving the mechanical properties of SBR/CAPB/clay NCs, as demonstrated by SEM and DMA. The maximum tensile strength of SBR/CAPB/clay NCs achieved 16.3 MPa at a clay loading of 40 phr, which is 10 times that of pure SBR. The tensile strength of the SBR/CAPB/clay NC incorporated with 20 phr clay has exceeded that of the SBR composite incorporated with 40 phr commercial organic clay. This work demonstrates that this strategy, which combines the CAPB-modification of SBR with the gel compounding method, is an effective and feasible method to improve the mechanical strength of SBR.本研究采用高效、简便的方法制备了椰酰胺丙基甜菜碱(CAPB)改性的高性能丁苯橡胶(SBR)/粘土纳米复合材料(NCs)。采用凝胶复配法将改性SBR与粘土凝胶复配，得到SBR/粘土复合材料。研究了工艺条件和CAPB对SBR/粘土复合材料力学性能的影响。XRD和TEM结果表明，CAPB成功地对SBR进行了亲水性改性，显著改善了SBR基体中粘土的分散性。SEM和DMA分析表明，黏土与SBR的相互作用增强，更多的SBR分子链被吸附到黏土上，显著改善了SBR/CAPB/clay NCs的力学性能。SBR/CAPB/clay NCs在40 phr黏土加载下的最大抗拉强度达到16.3 MPa，是纯SBR的10倍。掺加20phr粘土的SBR/CAPB/clay NC的抗拉强度超过掺加40phr商用有机粘土的SBR复合材料。研究表明，将capb改性SBR与凝胶复合相结合的策略是提高SBR机械强度的有效可行的方法。来源：复合材料力学仿真Composites FEM
