今日更新：Composite Structures 5 篇，Composites Part A: Applied Science and Manufacturing 2 篇，Composites Science and Technology 4 篇
Composite Structures
Periodic free vibrations of composite laminates with curvilinear fibres and CNTs
Hamed Akhavan, Pedro Camacho, Pedro Ribeiro
doi:10.1016/j.compstruct.2024.118598
曲线纤维和碳纳米管复合材料层合板的周期性自由振动
This article addresses the combined effect of using curvilinear fibres and carbon nanotubes (CNTs) reinforcements in the non-linear modes of vibration of laminated composite plates. To arrive at the material properties of the three-phase composite material, a two-step hierarchic procedure is followed. A modified version of the Halpin–Tsai model is employed to predict the Young’s modulus of the CNT enriched resin and expressions, deduced from equilibria of a unit cell where a fibre is embedded in resin, are applied to obtain the diverse elasticity moduli of the three-phase composite. Moderately large displacements are considered, with von Kármán strain–displacement relations. Although the presented model is an equivalent single layer one, it applies to thick plates, because a Third-order Shear Deformation Theory (TSDT) is followed. The set of autonomous non-linear equations of motion is reduced using static condensation and a modal basis with selected modes, chosen after a convergence analysis. The reduced set of equations of motion is solved by the shooting method. Numerical tests considering plates with diverse curvilinear fibre paths, CNT contents and thicknesses are carried out. The results obtained are thoroughly analysed.
Multi-objective parametric optimization problem is presented for overwrapped composite pressure vessels under internal pressure for storage and heating water. It is solved using the developed iterative optimization algorithm. Optimal values of design parameters for the vessel are obtained by varying the set of parameters for composite layers, such as the thickness of layers and radii of polar openings, which influence the distribution of fiber angles along the vessel. The suggested optimization methodology is based on the mechanical solution for composite vessels and the satisfaction of the main failure criteria. An innovative approach lies in the possibility of using the developed optimization methodology for designing vessels with non-symmetrical filament winding, which have unequal polar openings on the domes. This became possible due to the development of a special numerical mechanical finite element model of a composite vessel. A specific Python program provides the creation of a model and controls the exchange of data between the modules of the iterative optimization process. The numerical model includes the determination of the distribution of fiber angles on the domes and cylindrical part of the vessel as well as changes in layer thicknesses. The optimization problem solution is provided using a Multi-Island Genetic Algorithm, this type of method showed its efficiency for such applications, by allowing to avoid local solutions. Thus, optimal parameters of a composite vessel were found by minimizing composite mass and thickness and maximizing the strain energy. Test solutions using the developed methodology are presented for three types of composite materials to evaluate their possibility for integration into the vessel design model.
High-performance composite electrode based on polyaniline/graphene oxide carbon network for vanadium redox flow batteries
Amanpreet Kaur, Gurpreet Singh, Jun Woo Lim
doi:10.1016/j.compstruct.2024.118606
基于聚苯胺/氧化石墨烯碳网络的钒液流电池高性能复合电极
In this study, an electrode wrapped in a carbon network is fabricated using a straightforward hydrothermal technique. Conducting polymers such as polyaniline (PANi) have been used to form carbon networks on the surfaces of carbon fibers. However, the cycling instability of PANi, which is a consequence of structural modifications, is a significant obstacle to its commercial application. This study presents an innovative and effective approach for synthesizing carbon networks using PANi/reduced graphene oxide (PANi-rGO-CF) composites to enhance the performance of vanadium redox flow battery (VRFB) electrodes. PANi-rGO was deposited on carbon felt using a hydrothermal method, followed by calcination under an argon atmosphere. The presence of graphene oxide facilitated the uniform distribution of PANi and enhanced its stability. PANi-rGO-CF demonstrated superior electrocatalysis toward vanadium redox couples owing to the abundant heteroatom active sites, affording VRFBs with extraordinary stability and outstanding energy efficiency after 100 cycles at 100 mA/cm2.
This work represents a significant step toward integrating additive-manufactured honeycomb sandwiches into ship hull structures. The sandwich structure consists of two continuous fibre-reinforced thermoplastic faces and a regular honeycomb core made of chopped fibre-reinforced thermoplastic. The primary goal is to create optimal manufacturing and design methods to determine to which extent the sandwich solution that has been analysed may be used as a structural component of a fast patrol vessel. The core of the design procedure is a purposely developed evolutionary multiobjective optimisation routine suited to evaluate the flexural response of the structure under investigation. The analytical formulations utilised to predict the structural response of an additive-manufactured honeycomb sandwich subjected to 3-point bending have been derived using a combined analytical and experimental approach. A fast patrol vessel made of steel has been taken as a reference to demonstrate the capabilities of the proposed solution. A steel primary stiffener and its associated plate have been extracted from the midship section and replaced by an additively manufactured honeycomb sandwich. By maintaining the same structural encumbrances, it has been found that a pseudo-optimal combination of the mechanical properties of the sandwich base materials can accomplish an exceptional weight reduction of three times.
Ring stiffeners improve the buckling resistance of thin-walled hulls. In this study, theoretical models of buckling and strength failure of ring-stiffened composite hulls (RSCHs) were used to determine the design parameters. The hulls were prepared by filament winding on a mould composed of multi-petal-combined foams and steel shafts. The experimental results showed that the hydrostatic bearing performance of RSCHs was 1.79 times that of an unstiffened composite hull (USCH) with the same weight-to-displacement ratio (WDR). The crack in the damaged stiffened hulls penetrated the entire axis and expanded circumferentially, resulting in a stiffener fracture. Imperfections related to thickness deviations were introduced into a nonlinear buckling model by considering progressive damage. In contrast to the failure mechanism of USCH, the failure pressure of RSCHs was not at the peak of nonlinear buckling, and fibre compressive failure at 90° on the outermost layer of the skin was dominant. The error between simulated and experimental results was 4.64%. The parameter analysis indicated that the stiffener height and width had different effects on the buckling load. However, when only the same type of strength failure occurred, both were independent of the load. This study demonstrated the load-bearing advantages of RSCHs for ocean engineering applications.
Composites Part A: Applied Science and Manufacturing
Interlaminar properties of carbon fibre/epoxy laminates produced through a semi-curing process
Michael O’Leary, Robin Hartley, Arjun Radhakrishnan, Mark Mavrogordato, Turlough McMahon, James Kratz
doi:10.1016/j.compositesa.2024.108488
半固化碳纤维/环氧复合材料层间性能研究
The performance of semi-cured laminate interfaces with degrees of cure ranging from 0.3 to 0.9 was explored in Mode I and II, and compared to a baseline laminate produced through a single infusion and cure. The results showed that if the initially semi-cured element is kept to a degree of cure below the gel point prior to integration with the rest of the structure, average Mode I properties are retained to within 10 % of the baseline. At degrees of semi-cure above the gel point, a 33 % reduction in Mode I was measured, however, plasma pre-treatment mitigated this reduction to only 11 %. In Mode II, interlaminar properties are fully retained. Over the wide range of semi-cure studied, both resin flow and chemical cross-linking were observed, with the latter being more important to retain interfacial properties. The semi-curing process is considered a viable manufacturing method to produce composite laminates by resin infusion.
The use of digital thread for reconstruction of local fiber orientation in a compression molded pin bracket via deep learning
Richard A. Larson, Mohammad Nazmus Saquib, Jiang Li, Anthony J. Favaloro, Drew E. Sommer, Benjamin R. Denos, R. Byron Pipes, Sergii G. Kravchenko, Oleksandr G. Kravchenko
doi:10.1016/j.compositesa.2024.108491
通过深度学习，利用数字线重建压模销支架中的局部纤维方向
A deep convolutional neural network (DCNN) was used for microstructure reconstruction using artificial intelligence (MR-AI) by predicting local average fiber orientation distributions (FOD) in a 3D prepreg platelet molded composite (PPMC) pin bracket. To train the MR-AI model, surface strain fields from residual stresses simulated in PPMC plates were used as the input to the DCNN. A training dataset included PPMC plates with various degrees of global fiber alignment, based on the information obtained from high-fidelity flow simulation of a pin bracket. The MR-AI model was then deployed to analyze FOD in the 3D pin bracket by conducting thermo-elastic residual stress analysis. Initially, the MR-AI model was established entirely on the synthetic simulation data. Then, a μCT scan of a physically molded pin bracket was used to create a finite element model that provided data for additional validation of the DCNN model. For the μCT scan finite element pin bracket the MR-AI model predicted the distribution of fiber orientation tensor components with MAE of 0.10 indicating a global prediction error of 10 %. For the flow simulated pin bracket, the MR-AI model predicted the distribution of fiber orientation tensor components with a global prediction error of 11 %. The MR-AI model showed the ability to predict regions of varying alignment in the base and flange of the pin bracket. The proposed MR-AI methodology allows for rapid prediction of FOD in geometrically complex parts and offers a promising path to detecting unique fiber orientation states in molded components.
A Super-Stretchable Conductive Film with Strain-Insensitive Conductivity for Stretchable EMI Shielding Materials and Wearable Capacitive Strain Sensors
Strain-insensitive conductive films as stretchable electromagnetic interference (EMI) shielding materials and stretchable electrodes are highly desired in wearable electronics. However, fabricating super strain-insensitive conductive films under a tensile strain higher than 400% is still a great challenge. Herein, a super-stretchable conductive film based on the crumple-structured Ti3C2Tx nanosheets-single walled carbon nanotubes/stretchable substrate double-layers is designed for the stretchable EMI shielding materials and electrodes. The resulting film exhibits a strain-insensitive electrical conductivity as high as 3.01 × 103 S/m even at a strain up to 500%, which endows the film with a high and stable electromagnetic interference shielding efficiency (EMI SE) value of ∼ 45 dB. More interestingly, the EMI SE value of the film remains nearly constant even after 2000 cycles of 500% tensile strain, indicating the excellent long-term service stability as a stretchable EMI shielding material. Moreover, a capacitive strain sensor with extra-wide sensing range, ultra-high stability, and excellent durability is successfully achieved by employing the as-prepared films as stretchable electrodes. This work proposes a convenient strategy of strain-insensitive conductive film aiming to design stretchable EMI shielding materials and electrodes for wearable electronics.
Curing and reinforcement effect of recovered carbon black from waste tires on brominated butyl rubber
Guojie Zhang, Junjie Peng, Hanbing Wang, Yi Lu, Yong Zhang
doi:10.1016/j.compscitech.2024.110879
废轮胎再生炭黑对溴化丁基橡胶的固化及补强效果
The recycling of zinc compound from waste tires and the negative impact of zinc oxide on environment have been major challenges in rubber industry. In this study, the components and microstructure of recovered carbon black (rCB) from waste tires pyrolysis are analyzed, in which the content of the ash and zinc element is 20% and 6.1%, and zinc sulfide is the main zinc compound. Zinc sulfide and zinc oxide could crosslink brominated butyl rubber (BIIR), and the crosslinking effect becomes more effective in the presence of carbon black N660. BIIR can be crosslinked and reinforced by rCB in the absence of other additives. BIIR/rCB composites have similar curing behavior and mechanical properties to the BIIR composites filled with N660 and cured by zine oxide. Therefore, rCB could replace commercial carbon black N660 and zinc oxide in BIIR, and this replacement will realize the effective use of carbon black and zinc compound in rCB from waste tires and promote the sustainable development of tire industry.
Fumed Silica Additives Enables Tunable Wettability of the Resin for Improved Composite Bipolar Plate
Jing Chen, Nan Qin, Runlin Fan, Liming Jin, Junsheng Zheng, Pingwen Ming, Cunman Zhang, Jim P. Zheng
doi:10.1016/j.compscitech.2024.110882
气相二氧化硅添加剂使树脂的润湿性可调，用于改进的复合双极板
Composite bipolar plates (CBP) composed of resin and conductive filler are critical components in proton exchange membrane fuel cell (PEMFC) for achieving mechanical strength and electrical conductivity. The conductive filler entirely enveloped by resin is of significance for the flexibility of the CBP; while connected resin blocks the continued conductive channels and thus weakens the electrical properties of CBP. Herein, we propose a trade-off method between flexibility and conductivity of the CBP by wettability regulations of the resin, in which fumed silica additives are introduced into epoxy as composite adhesives. The abundant hydrogen bonds are demonstrated to be well-formed between epoxy and fumed silica for decreasing surface free energy (SFE) between resin and graphite. As a result, the composite adhesive with 2% fumed silica delivers moderate wettability enabling much improved CBP, which exhibits high electrical conductivity of 233.33 S cm-1 as well as flexural strength of 66.4 MPa. Moreover, the CBP also delivers improved areal specific resistance (5.34 mΩ cm2), thermal conductivity (10.58 W (m K)-1), and corrosion behaviors (0.0701 A cm-2) which guarantee the operation of the PEMFC. This work provides new insight from the wettability regulation of resins for improved CBP, which is an easy-operating method and has great potential for application in practical CBP fabrication.
由树脂和导电填料组成的复合双极板(CBP)是质子交换膜燃料电池(PEMFC)中实现机械强度和导电性的关键部件。完全被树脂包裹的导电填料对CBP的柔韧性有重要意义;而连接的树脂阻塞了持续的导电通道，从而削弱了CBP的电性能。在此，我们提出了一种通过树脂的润湿性调节来平衡CBP的柔韧性和导电性的方法，其中将气相二氧化硅添加剂作为复合粘合剂引入环氧树脂中。环氧树脂和气相二氧化硅之间形成了丰富的氢键，降低了树脂和石墨之间的表面自由能(SFE)。结果表明，含2%气相二氧化硅的复合胶粘剂具有中等润湿性，大大提高了CBP，其导电率达到233.33 S cm-1，抗折强度达到66.4 MPa。此外，CBP还提供了更好的面比电阻(5.34 mΩ cm2)、导热系数(10.58 W (m K)-1)和腐蚀性能(0.0701 A cm-2)，从而保证了PEMFC的运行。本研究从树脂润湿性调控方面为改进CBP提供了新的思路，该方法操作简便，在实际CBP制造中具有很大的应用潜力。
Temperature-Dependent Evolution of Synthetic Coal-Derived Graphite Fillers and Their Reinforcement in Styrene Butadiene Rubber Composites
Hao Zhang, Xiaoyu Ding, Yongjie Yang, Qinfu Liu, Leibo Ji, Kuo Li, Junmin Sun, Zhiming Sun, Qianyi Ma, Ying Wu, Xinyang Liu, Chul B. Park, Naisheng Jiang
doi:10.1016/j.compscitech.2024.110883
合成煤基石墨填料及其增强丁苯橡胶复合材料的温度演化
This study investigated the structural evolution of synthetic coal-derived graphite (SCG), produced from anthracite through high-temperature treatments ranging from 1000 to 2900 °C, and its reinforcement potential in styrene butadiene rubber (SBR) composites. Upon heating the anthracite to 2000 °C, We observed a gradual structural transformation from an amorphous carbon structure with mixed sp2-sp3 bonding to an ordered sp2-bonded nano-sized graphitic structure. This transformation was accompanied by the evaporation of heteroatom functional groups, an increase in high surface energy site as well as micropore and void structures, and enhanced hydrophobic surface property. Beyond 2000 °C, a flake-like graphite with a larger particle size (average lateral size > 10 μm) was gradually formed through lateral and vertical crystalline growth mechanisms. The reinforcing potential of SCG fillers was revealed by incorporating them into SBR and evaluating the properties of the resulting composites. It was found that the tensile strength and 300% tensile modulus initially enhanced with SCG fillers treated up to 2000 °C, but decreased for fillers treated at 2300 and 2900 °C. On the other hand, storage modulus, tear resistance, and gas permeability consistently improved with fillers treated at higher temperatures. These findings highlight the relationship between the temperature-induced structural evolution of SCG fillers and their reinforcement performance in SBR composites, offering valuable insights for industrial rubber applications, particularly enhancing the performance and sustainability of automotive tire formulations.
