今日更新:Composite Structures 3 篇,Composites Part A: Applied Science and Manufacturing 5 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 1 篇
Composite Structures
Analysis of laminated shells using pseudospectrals and the Reissner-Mixed Variational Theorem
S.C.F. Fernandes, J. Cuartero, A.J.M. Ferreira
doi:10.1016/j.compstruct.2024.118341
利用伪谱和赖斯纳-混合变分定理分析层叠壳体
In this paper, we combine the Carrera’s Unified Formulation CUF and a pseudospectral technique for predicting the static deformations and free vibrations behaviour of thin and thick cross-ply laminated shells. For the first time, the Reissner-Mixed Variational Theorem is used together with pseudospectrals to achieve a highly accurate technique. The accuracy and efficiency of this numerical technique for static and vibration problems are demonstrated through numerical examples.
Tailoring band gap properties of curved hexagonal lattices with nodal cantilevers
Shuvajit Mukherjee, Marcus Maeder, Milan Cajić, Felix Kronowetter, Sondipon Adhikari, Steffen Marburg
doi:10.1016/j.compstruct.2024.118342
用节点悬臂调整曲面六边形晶格的带隙特性
Metamaterials find applications across diverse domains such as electromagnetics, elasticity, and acoustics by creating band gaps. Lattice-based metamaterials also exhibit band gaps, which have a great potential to influence engineering design in vibration and noise reduction problems. The geometry of the repetitive unit cell in the lattice plays a crucial role in diversifying the location and number of stop bands across the frequency range. One of the key hurdles is devising unit cell architectures that can effectively suppress vibrations across diverse frequency ranges. This work proposes an innovative two-dimensional hexagonal lattice with tailored band gap characteristics through curved beam members and auxiliary cantilever beams at the nodes. We have thoroughly explored the impact of various design parameters on dispersion characteristics, wave directionality through iso-frequency contours of dispersion surfaces, and the transmission loss considering finite lattice. The investigation demonstrates an improvement in band gap characteristics, indicating the generation of more band gaps across the entire frequency range and the widening of the same. This study has the potential to serve as a future benchmark in the development of lattice-based elastic/acoustic metamaterials, particularly for addressing vibration reduction challenges at user-defined frequencies.
TRC truss – Proof of concept by experimental investigation
Dor Simon, Alva Peled, Yiska Goldfeld
doi:10.1016/j.compstruct.2024.118361
TRC 桁架--通过实验研究验证概念
The study develops textile-reinforced concrete (TRC) trusses, reinforced with 3D textiles. It is argued that, by taking advantage of textiles’ ability to conform to complex shapes and their corrosion resistance, TRC truss structures enable a substantial reduction in material and weight through efficient load transfer mechanisms. An experimental investigation explores the design methodology and manufacturing possibilities, as well as the macro-structural response and the cracking and failure mechanisms under flexural loading. Additionally, the study investigates the effects of various reinforcement layouts associated with different anchoring feasibilities and reinforcement ratios on the structural performance.It was found that TRC trusses maintain their structural performance compared to full cross-sectional rectangular TRC beams while achieving significant material savings and weight reduction (about 50 %). It was also found that effective anchoring is a dominant parameter governing structural response. Results from this study highlight the high potential of TRC trusses as a sustainable alternative for structural components.
Composites Part A: Applied Science and Manufacturing
Paper fiber-reinforced polypropylene composites from nonwoven preforms: A study on compression molding optimization from a manufacturing perspective
Cecile A. Grubb, David J. Keffer, Christopher D. Webb, Marton Kardos, Hendrik Mainka, David P. Harper
doi:10.1016/j.compositesa.2024.108339
无纺布预制件中的纸纤维增强聚丙烯复合材料:从制造角度优化压缩成型的研究
This work optimizes compression molding manufacturing for wet-formed nonwoven paper and polypropylene fiber mats. A central composite designed experiment investigated the effects of fiber reinforcement concentration, compression molding temperature, pressure, and time on composite laminate performance. We assess the composites’ density, panel thickness, water uptake, flexural behavior, and Izod impact strength. Models predicted and optimized composite performance using objective function analysis with penalties applied for undesirable conditions, such as processing time or low reinforcement concentration. Paper fiber content has the largest impact on composite properties, followed by processing time, molding pressure, and temperature. Composite optimization depends on penalty conditions; low fiber content penalties favor low fiber content panels with short processing times, while high fiber content penalties favor high fiber content panels with long processing times. This work suggests that molding composites with a greater fraction of renewable feedstock requires a commensurate increase in processing intensity.
Fabrication of a high-temperature resistant and water-soluble sizing agent to significantly improve the interfacial properties of carbon fiber reinforced epoxy composites
Baowei Qiu, Youquan Ling, Xiwen Gu, Lei Wang, Fei Chen, Shengtai Zhou, Huawei Zou, Mei Liang
doi:10.1016/j.compositesa.2024.108344
制备耐高温水溶性施胶剂,显著改善碳纤维增强环氧树脂复合材料的界面性能
Applying suitable sizing agents is effective in improving the interfacial performance of carbon fiber reinforced composites (CFRPs). However, the poor thermal stability of conventional epoxy-based sizing agent limits their application at elevated temperatures for preparing advanced CFRPs. The question could lead to interfacial damage of composites at high temperatures, thus deteriorating their mechanical properties. In this work, diethanolamine (DEA) was selected to modify E51 resin to obtain a high-temperature resistant sizing agent (E51@DEA). The decomposition temperature of E51@DEA was 320 °C, which was 140 °C higher than that of E51. Furthermore, the resultant composites treated by E51@DEA 2 % showed robust interfacial performance (ILSS = 74.2 MPa, IFSS = 100.70 MPa), which was both increased by about 25 % compared to unmodified samples. In addition, the modified fiber could completely retain their interfacial reinforcement after treatment at 300 °C for 4 h. The prepared composites combined excellent thermal and interfacial properties, further expanding the application range of CFRPs.
Influence of Flow-Induced crystallization and morphology on mechanical behavior in long discontinuous glass fiber polyamide composites
Siavash Sattar, Jimesh Bhagatji, Mohammad Nazmus Saquib, Diego Pedrazzoli, Mingfu Zhang, Sergey G. Kravchenko, Oleksandr G. Kravchenko
doi:10.1016/j.compositesa.2024.108353
流动诱导结晶和形态对长非连续玻璃纤维聚酰胺复合材料机械行为的影响
This study investigates the combined flow-induced crystallization in the polymer and fiber reorientation during compression molding of a long discontinuous glass fiber polyamide (PA) 6 composite. The composite is molded from an organosheet (a semi-finished pre-impregnated mat); the composite anisotropic tensile properties are evaluated as a function of polymer crystalline morphology and fiber orientation state, both controlled by the extent of material flow in the mold. To study these effects, the full mold coverage and partial center charge of organosheet (OS)-80 %, 60 %, 50 %, and 40 % were compression molded to cause varying anisotropic material flow. Tensile specimens were cut out from the molded plates in the flow and transverse direction and tested to compare their effective tensile properties (modulus and strength). The flow-induced morphological changes in a molded composite at the glass fiber bundle microstructure scale and polymer crystalline phases nano-structure were characterized using optical microscopy and X-ray diffraction, respectively. These morphological changes contributed to the significant change in the tensile strength and modulus; a combined experimental/numerical simulation framework was used to segregate the relative contribution of each factor. Experimentally, the tensile modulus increased in the flow direction from 9.6GPa to 14.9GPa for the specimens produced by full mold coverage and OS-50 % coverage mold, respectively. The tensile strength increased from 162 MPa to 254 MPa for the full and OS-60 % mold coverage. On the contrary, the strength and modulus in the transverse direction to the flow showed a significant drop to 35 MPa and 3GPa, respectively, which was attributed to reduced fiber alignment and anisotropy in the PA6 matrix.
Thermoviscoelastic modelling of highly reactive thermoset resins for liquid moulding applications
Leonardo Barcenas, Loleï Khoun, Pascal Hubert
doi:10.1016/j.compositesa.2024.108350
用于液体成型应用的高活性热固性树脂的热变弹性建模
This paper presents a methodology for developing thermo-mechanical properties model for highly reactive resins and its use for Resin Transfer Moulding process (RTM) modelling and prediction of residual stresses. Cure Hardening Instantaneously Linear Elastic (CHILE), and Thermoviscoelastic (TVE) models, were implemented to analyze the mechanical behaviour of the resin. Simulation of the RTM process was developed and applied to a representative curved plate geometry. An integral approach was considered where the degree of cure gradient, generated during the filling stage due to the reactivity of the resin, was implemented as initial condition of the stress-deformation process simulation. The validation process included fabricating experimental parts with the representative geometry. The degree of cure variation of highly reactive thermosets during injection caused a significant effect on the final shape of the parts. These effects were captured by the simulations, where the TVE model showed a more accurate prediction of the part distortion.
Silicone elastomer dielectric composites by introducing novel O-MMT@TiO2 nanoparticles for energy harvesting application
Tao Yang, Chongyang Wang, Ling Liu, Liqun Zhang
doi:10.1016/j.compositesa.2024.108351
引入新型 O-MMT@TiO2 纳米粒子的硅树脂弹性体介电复合材料的能量采集应用
Dielectric elastomers have attracted attention in emerging advanced electromechanical applications. However, how to simultaneously improve the dielectric constant and the breakdown strength of dielectric composite needs to be solved. In this paper, we propose a new strategy to anchor TiO2 nanoparticles onto organically modified montmorillonite (O-MMT) nanoplatelets through dehydration reaction to synthesize a novel filler O-MMT@TiO2. Then, the O-MMT@TiO2 is incorporated into methyl vinyl silicone rubber (MVSR) matrix to obtain O-MMT@TiO2/MVSR dielectric composites. Comparing with the composites by direct mixing of TiO2 and O-MMT in MVSR (O-MMT/TiO2/MVSR), O-MMT@TiO2/MVSR composites significantly increase mechanical and dielectric and energy storage properties. 30 wt% O-MMT@TiO2/MVSR composite achieves the highest energy storage density of 118.65 kJ/m3, which is 142.9 % higher than that of 15 wt%O-MMT/15 wt%TiO2/MVSR (48.84 kJ/m3). This study offers an effective method for the preparation of high-performance dielectric elastomer materials, which can be exploited for the energy harvesting application.
An experimental and analytical study of mode I fracture and crack kinking in thick adhesive joints
Ali Shivaie Kojouri, Javane Karami, Kalliopi-Artemi Kalteremidou, Jialiang Fan, Akash Sharma, Anastasios P. Vassilopoulos, Veronique Michaud, Wim Van Paepegem, Danny Van Hemelrijck
doi:10.1016/j.compositesb.2024.111695
厚粘合剂接头 I 型断裂和裂缝扭结的实验和分析研究
This study investigates the fracture behavior of thick adhesive joints manufactured with composite adherends and bonded with an epoxy-based structural adhesive common to the wind turbine industry. For that purpose, double cantilever beam specimens with an adhesive thickness of approximately 10 mm and different pre-crack lengths are manufactured and tested under mode I loading. Analytical approaches are compared to assess the energy release rate, including the simple beam theory, modified beam theory, compliance calibration method, and beam on an elastic and elastic-plastic foundation. In order to evaluate the applicability of the analytical approaches, an in-situ measurement method based on Digital Image Correlation is also employed to determine the energy release rate of the thick adhesive joints. The crack propagation angle is determined theoretically using the second-order crack kinking theory. A good correlation is observed between the theoretical predictions and experimental results. Furthermore, it is demonstrated that due to the T-stress, the crack tends to deviate from the middle of the joint and propagate towards the interface. By comparing different data reduction methods to evaluate the energy release rate of thick adhesive joints, recommendations for their fracture analysis are made, pinpointing the beam on an elastic and elastic-plastic foundation as the most suitable model.
本研究探讨了用复合材料粘合剂制造并用风力涡轮机行业常用的环氧基结构粘合剂粘合的厚粘合接头的断裂行为。为此,制作了粘合剂厚度约为 10 毫米、预裂缝长度不同的双悬臂梁试样,并在模式 I 载荷下进行了测试。比较了评估能量释放率的分析方法,包括简单梁理论、修正梁理论、顺应性校准方法以及弹性和弹塑性基础上的梁。为了评估分析方法的适用性,还采用了基于数字图像相关性的现场测量方法来确定厚粘合剂接头的能量释放率。裂缝扩展角是利用二阶裂缝扭结理论从理论上确定的。理论预测与实验结果之间存在良好的相关性。此外,实验还证明,由于 T 形应力的作用,裂纹倾向于偏离接头中部并向界面方向扩展。通过比较不同的数据还原方法来评估厚粘接接头的能量释放率,为其断裂分析提出了建议,并指出弹性和弹塑性基础上的梁是最合适的模型。
Composites Science and Technology
Bending shape memory properties and multi-scale viscoelastic behaviors of knitted-fabric reinforced polymer composites
Ying Huang, Haipeng Ren, Yang Liu, Weilin Xu, Wei Zhao
doi:10.1016/j.compscitech.2024.110747
针织织物增强聚合物复合材料的弯曲形状记忆特性和多尺度粘弹性行为
Knitted fabrics with easily deformable loop structure have the potential in the development of shape memory polymeric composites with large recovery deformations. The knitted fabric reinforced shape memory epoxy polymer composites (SMPC) were prepared in this work. The effects of loop densities, orientations and bending radii on shape memory properties of SMPC were investigated. The shape fixity ratio and shape recovery ratio of SMPC subjected to U-shaped bending radius of 5 mm are above 98%. The shape recovery force of SMPC can reach up to 5.9 N. The thermodynamic properties of SMP were also characterized to obtain mechanical parameters and a user-defined material subroutine (UMAT) of shape memory epoxy polymer (SMEP) was written. Based on viscoelastic theory and the multi-scale geometrical structures, the macroscopic homogeneous thermodynamic model and mesoscopic thermodynamic model of knitted fabric reinforced SMPC were established to study the macro-scale stress distribution and meso-scale deformation evolution during shape memory process, respectively. The neutral surface position of SMPC during bending deformation is offset inner. The unique anisotropic loop structure of knitted fabric determines the shape memory behavior of the SMPC. Finally, micro-CT characterizations of knitted fabric reinforced SMPC were conducted to further understand the loop deformation mechanism during shape memory process. This study will provide important theoretical and technical support for large deformation structure design and deformation prediction of smart composites.