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 Structures
Multi-scale concurrent topology optimization of cellular structures with multiple microstructures for minimizing dynamic response in the time domain
Jian Wang, Yan Zhang, Xiaoyu Wang, Xuyang Zheng, Zhiyong Ma, Wei-Hsin Liao, Nan Zhu, Qiang Gao
doi: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 deformation
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
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.
Experimental and numerical analysis of low-velocity impact and compression after impact responses of novel 3D hybrid composites
Ke Wang, Farid Taheri
doi: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.
Composites Part A: Applied Science and Manufacturing
Uncut fiber analysis using fiber deflection and cutting forces in carbon fiber-reinforced plastics during rotation of the cutting tool
Dong-Gyu Kim, Seung-Han Yang
doi: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.
Bamboo as a natural optimized fiber reinforced composite: interfacial mechanical properties and failure mechanisms
Xiaohan Chen, Xianke Wang, Xun Luo, Lin Chen, Yuquan Li, Jiarui Xu, Zengqian Liu, Chunping Dai, Hu Miao, Huanrong Liu
doi: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.
A novel strategy to prepare rubber/clay nanocomposites via compounding clay gel into cocoamidopropyl betaine modified styrene butadiene rubber
Zilong Chen, Jian Li, Zhanxu Li, Jun Lin, Liqun Zhang, Shaojian He
doi: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.
