今日更新：Composite Structures 7 篇，Composites Part A: Applied Science and Manufacturing 2 篇，Composites Part B: Engineering 2 篇，Composites Science and Technology 1 篇
Composite Structures
Effect of thermal and electric coupling on the multifield response of laminated shell structures employing higher -order theories
Francesco Tornabene, Matteo Viscoti, Rossana Dimitri
doi:10.1016/j.compstruct.2024.118801
热电耦合对层合壳结构多场响应的影响
The paper introduces a refined formulation, based on higher-order theories, for the thermo-electro-elastic analysis of laminated shell structures made of smart materials. The formulation employs a generalized higher-order model to describe the configuration variables, following the Equivalent Single Layer and Equivalent-Layer-Wise approaches. After presenting an effective homogenization procedure for thermo-electro-elastic smart composites, the fundamental equations are derived in curvilinear principal coordinates, taking into account the coupling effects among mechanical elasticity, electricity, and heat conduction. A semi-analytical solution is then obtained using Navier’s method. Furthermore, the three-dimensional response of the panel is determined through a recovery procedure that applies the Generalized Differential Quadrature (GDQ) numerical method. Numerical examples are provided, where the formulation is applied to both straight and curved panels subjected to various surface actions. These examples point out the coupling effect between different physical phenomena on the multifield three-dimensional response. Furthermore, the numerical results based on the proposed formulation are verified to be consistent with predictions from finite-element-based models, despite the reduced computational cost. The manuscript enables in a simple way the study of physical couplings between different fields that are not considered in most commercial software. As a result, this formulation offers a valuable tool for designing doubly-curved laminated panels made of innovative smart materials for novel engineering applications
Defect formation mechanism in the shear section of GH4099 superalloy honeycomb under milling with ice fixation clamping
Shaowei Jiang, Daomian Sun, Haibo Liu, Yueshuai Zuo, Yang Wang, Jianming Li, Kuo Liu, Yongqing Wang
doi:10.1016/j.compstruct.2024.118812
冰固夹铣削下GH4099高温合金蜂窝剪切断面缺陷形成机理
Superalloy honeycomb cores excel in corrosion, high temperature, and impact resistance. They are used in key aircraft structures under extreme conditions. To reduce the application difficulty of honeycomb core materials, cutting the samples is essential. Fracture zones or burrs on machined walls weaken welding strength. Based on shear fracture theory, the fracture form of honeycomb wall was determined to be shear fracture. A single factor cutting experiment with controlled cutting state of single tooth was designed. The Johnson-Cook model and a finite element simulation were established. The effect of cutting state parameters on stress distribution and morphology was explained, and the defect formation mechanism under ice fixation clamping milling was revealed. The research results show that the cutting-in angle and single-tooth cutting width significantly impact the stress distribution and morphology of the honeycomb wall shear section. At a 30° cutting-in angle, Y and Z direction tensile stress is lower. The shear section quality is satisfactory, with 95 % shear zone height and 24.77 μm cut-out burr height. At a 0.01 mm single-tooth width, overall stress on the honeycomb wall is minimal, at only 1.892GPa. The shear section quality is better, with 80 % shear zone height and 20.61 μm cut-out burr height. Shear zone height first decreases then increases with the cutting-in angle and is inversely proportional to single-tooth cutting width, while fracture zone height shows the opposite trend. Cut-out burr height is proportional to the cutting-in angle, single-tooth cutting width, and cutting depth. Cutting speed has a minimal effect on section quality. The shearing section quality of honeycomb wall can be improved by using smaller single-tooth cutting width, cutting-in angle and cutting depth and moderately increasing cutting speed.
3D textile-structured tubular composites currently suffer from problems with single cross-sectional shapes and low energy absorption efficiency. To address the above problems, this study proposes a novel tubular structure inspired by the bamboo structure, characterized by a concentric nested structure of “double tubes & double ribs.” Bio-inspired novel 3D woven tubular composites (3D-WBBTC) with the above structures were prepared using the VARTM process, aiming to enhance the energy absorption of 3D woven tubular composites. The axial compression performance and energy absorption performance of 3D-WBBTC were studied using quasi-static axial compression tests and finite element numerical simulations. The results show that the specific energy absorption ranges from 7.41 to 11.59 J·g−1 and compression force efficiency ranges between 0.50 and 0.75, significantly improved compared to traditional 3D woven tubular composites. The damage mode of 3D-WBBTC is a hybrid damage mode of “local buckling of the tube wall & partial folding of the ribs,” which includes debonding of the fiber-resin interface, different forms of fiber breakage, and peeling, shedding, and cracking of the resin. It provides a new approach to the innovative design of 3D woven tubular composites.
Nature-inspired materials, especially those derived from triply periodic minimal surfaces (TPMS), have garnered significant attention in the engineering field due to their unique topological properties. However, their applications are limited by the complexities of the design process. With the development of deep learning in the design of metamaterials, this study aims to address the issue of insufficient datasets related to metamaterials by constructing a point cloud dataset of TPMS cells and their equivalent elastic modulus. This dataset is used to train an improved Warping Generative Adversarial Networks (GAN) to learn the mapping relationship between the equivalent elastic modulus and structure. Subsequently, the generated TPMS cells are reconstructed, and their performance is validated through experiments and relevant evaluation metrics. This approach differs from traditional 2D and 3D dimensionality-reduction inverse design methods, as it allows for the retrieval of structures from the network outputs through simple point cloud reconstruction, thereby avoiding a complex modeling process. The introduced 3D structural inverse design method enables the generation of complex and realistic 3D structures, potentially advancing the development of metamaterials design.
Shear stiffness model for an innovative Y-shaped connector with UHPC grout in composite structures
Yulong Ni, Menghan Hu, Zhenlei Jia, Qiang Han
doi:10.1016/j.compstruct.2024.118817
新型超高性能混凝土灌浆y形接头复合结构抗剪刚度模型
Precast concrete deck panels (PCDPs) with shear pockets offer several advantages to accelerate bridge construction. In this paper, a Y-shaped connector was proposed, which was placed intermittently in the ultra-high-performance concrete (UHPC) shear pockets of PCDPs in composite structures. To assess the shear behavior of the Y-shaped connector, push-out tests were performed by varying plate width and thickness, diameter of the penetrating rebar and perfobond hole, and type of grout. The load-slip curves, failure modes, strain analysis, and shear behaviors were investigated. Then, validated finite element (FE) models were established to investigate the relationship between the shear stiffness and number of perfobond holes. Finally, the shear stiffness model of the Y-shaped connector considering the end-bearing resistance of the UHPC was proposed. The test results show that the Y-shaped connector with UHPC grout has excellent shear performance compared to the specimen with normal concrete (NC) grout. The shear stiffness of the Y-shaped connector is greatly influenced by the effective width of the perfobond plate. The shear stiffness of the Y-shaped connector increases significantly with the number of perfobond holes. The analytical model has a precise prediction for the shear stiffness of the Y-shaped connector.
A novel digital unit cell library generation framework for topology optimization of multi-morphology lattice structures
Jinlong Liu, Zhiqiang Zou, Kang Gao, Jie Yang, Siyuan He, Zhangming Wu
doi:10.1016/j.compstruct.2024.118824
一种用于多形态点阵结构拓扑优化的新型数字单元库生成框架
Although single-unit cell lattice structures are commonly used in engineering, multi-morphology composite lattice structures offer enhanced mechanical properties and diverse functionalities by tailoring their microstructures. This study presents a novel framework for generating a digital unit cell library to optimize the design of multi-morphology lattice structures. The framework involves creating the library using modular encoding and an adjacency matrix while addressing connectivity constraints. A voxel model is employed to streamline the homogenization process of the various unit cells in the library. This homogenization dataset trains a Radial Basis Function Neural Network (RBFNN) to evaluate the elasticity tensor of the unit cells. The compliance of the multi-morphology lattice structure is minimized by identifying optimal unit cell volume fractions and types through topology optimization and 0–1 integer programming. The former utilizes sensitivity analysis via RBFNN to determine the optimal volume fractions, while the latter focuses on minimizing the element strain energy and considers constraints that satisfy the optimal volume fractions of unit cells. The effectiveness and feasibility of this method are demonstrated through three benchmark numerical examples. Experimental results from additive manufacturing samples show that the proposed multi-morphology lattice structures achieve a 44.24% increase in initial stiffness and a 47.70% increase in ultimate strength compared to single-unit cell lattice structures.
Rectangular seawater sea-sand concrete columns using steel-FRP composite bars and closed-type winding FRP ties: Axial behavior and confinement model
Gang Xiao, Wei Tan, Shiwen Han, Peirong Mai, Jinping Ou
doi:10.1016/j.compstruct.2024.118826
采用钢-FRP复合筋和封闭式缠绕FRP筋的矩形海水海砂混凝土柱：轴向性能及约束模型
Seawater sea-sand concrete (SWSSC) columns reinforced with steel-fiber reinforced polymer (FRP) composite bars (SFCBs) and closed-type winding FRP ties (CWFTs) are highly suitable for marine environments. However, due to limited research, the axial performance and confinement model of the columns have not been fully clarified. Therefore, axial compression tests of the columns in the study reveal that larger volumetric stirrup ratios and appropriate tie configurations can significantly enhance column ductility. Specifically, compared to columns with a 1.75% stirrup ratio, the strain ductility coefficients of columns with ratios of 3.44% and 4.55% increase by 54% and 195%, respectively. The coefficient of columns with B-configuration ties is 2.86 to 4.34 times that of columns with A-configuration ties. The impact of stirrups’ cross-sectional area and spacing on axial behavior is similar, and the effect of stirrups’ width-to-thickness ratio is minimal. Compared to steel-tie columns, CWFT columns with various tie configurations and volumetric stirrup ratios exhibit similar load–strain curves before the peak load and lower axial capacity. With the same stirrup ratio, steel-tie columns demonstrate better ductility than CWFT columns with A-configuration ties, but for B-configuration ties, the ductility coefficient of CWFT columns is 2.23 times that of steel-tie columns. Factors influencing the stress–strain curve of CWFT-confined concrete include the strength in the bent section, stirrup configuration, spacing, volumetric ratio, and elastic modulus of stirrups. Peak stress and strain are associated with the latter four factors, and the first four coefficients influence ultimate stress and strain. Formulas for calculating the axial capacity and confinement model have been derived and show good agreement with the experimental results. The bearing capacity, ductility and complete stress–strain curves of the columns under axial compression can be predicted, promoting the development of marine civil engineering.
Composites Part A: Applied Science and Manufacturing
Characterising pore networks and their interrelation with the fibre architecture in unidirectional composites
S. Gomarasca, D.M.J. Peeters, B. Atli-Veltin, T. Slange, G. Ratouit, C. Dransfeld
doi:10.1016/j.compositesa.2024.108669
表征孔隙网络及其与单向复合材料纤维结构的相互关系
This work proposes a methodology for the characterisation of complex pore features in unidirectional composite prepregs, and provides insights into the interaction between fibre architecture and pores. The method showcased allows to compare spatial distributions at a three-dimensional level, highlighting in the tape analysed a significant correspondence between regions of elevated tortuosity and increased pore fractions. Regions associated with highly tortuous meandering fibres exhibit a pronounced association with porosity located both in the bulk and at the tape surface, suggesting a strong interaction between non-collective fibre displacement and the probability of pore location. Furthermore, our study quantifies the length scale of feature propagation, shedding light on the spatial extent of microstructural pore occurrence within the composite. These findings have significant implications from a characterisation perspective to aid modelling approaches and manufacturing processes for high-performance composite prepregs tapes.
Impact damage and low temperature effects on carbon fiber/epoxy joints: A comparative study of hybrid bolted/bonded and bolted configurations with cross-ply and angle-ply laminates
Mahsa Seyednourani, Sercan Akgun, Hasan Ulus, Mehmet Yildiz, Hatice S. Sas
doi:10.1016/j.compositesa.2024.108677
碳纤维/环氧树脂接头的冲击损伤和低温效应：交叉层合板和角层合板混合螺栓/粘结和螺栓配置的对比研究
This study investigates the tensile and tensile after impact (TAI) performance of hybrid bolted/bonded (HBB) and only bolted (OB) carbon fiber/epoxy composite joints with cross-ply (CP) and angle-ply (AP) stacking sequences under low-temperature (LT) conditions. The focus is on the behavior of these joints under low temperatures with barely visible impact damage (BVID), relevant to aerospace and high-performance industries. In situ acoustic emission (AE) analysis and fractographic examinations synergistically evaluate the effects of LT (−55 °C) and BVID (10 J energy level) on these joints. Results indicate that HBB-CP intact joints exhibit higher load-bearing capacity at LT due to increased adhesive and matrix stiffness but demonstrate more brittle responses. The combined impact of low temperature and impact loading significantly affects impacted CP joints, leading to notable damage and reduced load-bearing capacity. Although HBB-CP joints are more susceptible to BVID than OB-CP joints, they still outperform overall. AE and fractographic analyses reveal fiber-related failures in CP laminates and matrix/interface failures in AP laminates, with increased matrix cracking at low temperatures. This research provides a comprehensive analysis of the interplay between impact dynamics, temperature variations, and stacking sequence configurations on hybrid and bolted composite joints.
Thermo-mechanical analysis of extreme thermal loads on a flax fiber composite sandwich footbridge
Marco Manconi, Ali Shahmirzaloo, S.P.G. Faas Moonen
doi:10.1016/j.compositesb.2024.112084
亚麻纤维复合材料夹层人行桥极端热载荷热力学分析
In this study, a framework is proposed to perform a thermo-mechanical analysis under an extreme thermal weather event. The objective is to evaluate the temperature-induced responses as they represent a critical factor in the durability and safety of bridges. The 15m flax fiber composite sandwich footbridge case study used for validation is instrumented with 82 fiber Bragg grating (FBG) sensors and 8 thermocouples, and it is located in Almere, the Netherlands. The structural response is evaluated under an extreme weather condition obtained through an extreme value analysis (EVA) on an hourly 18-year dataset of solar radiation and air temperature. A peak-over-threshold (POT) strategy is adopted to extract extreme values. The extremes are fitted by a generalized Pareto distribution (GPD) to obtain the 50-year temperature and global solar radiation. The framework combines environmental data, point-by-point solar radiation analysis with sun sheltering, 3D transient heat transfer, and a sequentially coupled (one-way) mechanical analysis in Abaqus. The thermal simulation accuracy is first verified against in-situ measurements. Subsequently, the extreme thermal load is applied and quantified. The results prove that the resultant stresses are significant (up to 26%) concerning the compressive, tensile, and shear characteristic strength of the lamina.
Lightweight composite meta-lattice structures with inertial amplification design for broadband low-frequency vibration mitigation
Lanhe Xu, Zhou Yang, Zhilin Zhang, Eric Li, Jie Zhou, Bing Li
doi:10.1016/j.compositesb.2024.112091
具有惯性放大设计的轻型复合元晶格结构用于宽带低频振动抑制
Designing lightweight structures with superior low-frequency vibration attenuation and high mechanical properties remains a significant challenge. Here, we propose a novel design strategy for lightweight meta-lattice sandwich structures that not only exhibit enhanced low-frequency vibration attenuation but also maintain optimal load-bearing performance. By introducing an inertial amplification mechanism, we achieve a broadening effect on the low-frequency bandgap. We develop analytical models based on the Rayleigh-energy method and cantilever-beam equivalence to theoretically predict the dynamic properties. Glass fiber reinforced (GFR) nylon composite meta-lattice sandwich panels are fabricated via selective laser sintering (SLS) 3D printing. A self-developed, fully automated laser-vibration-measurement platform is employed to confirm the significant improvement in broadband low-frequency vibration-reduction performance of the proposed meta-lattice structures. The practical application of a meta-lattice sandwich tube demonstrates its effectiveness in providing low-frequency broadband vibration attenuation and high load-bearing capacity, while maintaining a lightweight design.
A Flexible Metamaterial Based on CNTs/Cellulose Aerogels for Broadband and Ultra-lightweight Microwave Absorbers
Lifei Du, Yuekun Li, Qian Zhou, Tiantian Shi, Liangqing Zhang, Jiong Wang, Xinlei Wang, Xiaomeng Fan
doi:10.1016/j.compscitech.2024.111024
基于碳纳米管/纤维素气凝胶的宽带和超轻量微波吸收材料
Lightweight aerogel composites derived from biomass represent a promising candidate for electromagnetic wave absorption. In this study, the CNTs/cellulose aerogels three-dimensional (3D) sheet-networks were prepared via the homogenous freezing method, and a two layered meta-structure with periodic square resin shells was designed and optimized to further improve the absorbing properties of the CNTs/cellulose aerogels. The metamaterial absorber with the prepared CNTs/cellulose aerogel filling into the shells achieved ultra-broadband electromagnetic wave absorption in the frequency range of 4.36-40 GHz with a thickness of 8.5 mm (The relative bandwidth of the fabricated metamaterial absorber reaches 160.7%). Particularly, the radar cross-section properties of the curved CNTs/cellulose aerogel metamaterial absorber were investigated, revealing its application potential for conformal absorption devices, which would provide a new strategy for the design of ultra-lightweight conformal materials with broadband electromagnetic absorption materials.
