今日更新：Composite Structures 8 篇，Composites Part A: Applied Science and Manufacturing 1 篇，Composites Part B: Engineering 11 篇，Composites Science and Technology 7 篇
Composite Structures
Damage indicators in unidirectional natural fibre composites under fatigue loading
Ali Moghimi-ardekani, Jianqun Hao, Stepan V. Lomov, Jan Ivens, Aart Willem van Vuure
doi:10.1016/j.compstruct.2024.118522
单向天然纤维复合材料疲劳载荷下的损伤指标
This paper investigates the occurrence of failure under fatigue loading of unidirectional flax fibre composites with different matrices. Various parameters, such as dissipated energy, residual strain, and stiffness, were measured to evaluate fatigue damage and the fatigue life of composites. The results indicate that absolute dissipated energy may not be the most suitable indicator for assessing damage in natural fibre composites when they are subjected to fatigue before reaching failure. The research proposes to rather consider the “loss factor”, defined as the ratio of dissipated energy to total energy stored in each cycle. This indicator appears to provide a more effective means of evaluating fatigue life of the studied composites, especially when compared to the dissipated energy observed during fatigue tests at low stress levels. Fatigue and acoustic emission results indicate that biocomposites with better fibre–matrix adhesion show a delayed damage initiation and propagation, as well as longer fatigue life.
A novel layup process for reducing surface thermal distortion of CFRP laminate reflector
Kangcheng Yin, Qingchao Sun, Zhihao Fan, Xiaokai Mu, Fei Wang
doi:10.1016/j.compstruct.2024.118517
一种减少CFRP板反射器表面热变形的新型铺层工艺
This study proposes a novel anti-symmetric folding layup process to reduce the surface thermal distortion of carbon-fiber-reinforced polymer (CFRP) reflector. Firstly, theoretical equations regarding the influencing factors of surface thermal distortion in CFRP reflector are derived, and the concept and advantages of the anti-symmetric folding layup process are introduced. Secondly, free thermal expansion analysis considering the ply angle misalignment is conducted, showing that the novel process can reduce surface thermal distortion by 36.13 % compared to traditional process. Finally, experimental samples with different layup processes are designed and manufactured, and their surface thermal distortion is detected using shear speckle interferometry. The experimental results show that compared with the traditional symmetric layup process, the double anti-symmetric folding layup process can reduce the surface thermal distortion of CFRP reflector by 32.39 %, demonstrating significant advantages in thermal stability and strong potential for practical engineering applications.
Shear behavior of pre-damaged RC beams strengthened with UHPFRC-CFRP grid layer
Jiyang Shen, Hongzhe Dai, Guangchun Zhou, Jun Shi
doi:10.1016/j.compstruct.2024.118520
UHPFRC-CFRP网格层加固预损伤RC梁的抗剪性能
Ultra-high performance fiber reinforced concrete (UHPFRC), incorporating recycled tyre fibers, and carbon fiber-reinforced polymer (CFRP) grid were utilized to strengthen the pre-damaged reinforced concrete beams caused by coupling action of sustained loads and marine environment. The failure modes, characteristic loads, deflection features, and strain behavior of the strengthened beams with various types of UHPFRC, thicknesses of UHPFRC layers, CFRP grid ratios, and CFRP grid layout angles were investigated. The results indicated that they exhibited the typical shear failure, and their characteristic loads increased by 102 %-205 % compared to the undamaged beam. By increasing the thickness of the UHPFRC layer and the CFRP grid ratio, and adopting 45° CFRP layout angle, the cracking stiffness, energy absorption capacity, and shear force sharing ability would be further improved, while adopting the UHPFRC incorporating recycled tyre fibers would decrease the ductility. Moreover, analytical models were developed to calculate the ultimate loads, manifesting reasonable accuracy.
On the random vibration-based progressive fatigue damage detection and classification for thermoplastic coupons under population and operational uncertainty
The problem of vibration-based progressive fatigue damage detection and Fatigue State (FS) determination for thermoplastic coupons is experimentally addressed under significant population and experimental uncertainty. The study involves 13 coupons subjected to tension–tension fatigue testing with interruptions at 10,000-cycle intervals. Utilizing non-parametric random vibration analysis and a robust, uncertainty-tolerant methodology, the research employs Multiple Model Representations of uncertain dynamics through parametric ARMA(AutoRegressive-Moving Average)-type random vibration response modeling. Results, validated by ultrasonic C-Scan testing, reveal (a) the significance of uncertainties, (b) a resonant structural frequency indicating fatigue accumulation, (c) remarkable detection performance, achieving 100 % accuracy even at 10,000 cycles, and (d) FS determination with over 80 % accuracy across all coupons. This study offers promising avenues for automated fatigue damage detection and FS determination in thermoplastic structures, eliminating the need to interrupt their operational cycles.
Multicomponent functional scaffolds hold great promise as implanted materials with compatible mechanical properties and biological functionalities. Interpenetrating phase composites (IPCs) with biomimetic multiscale porosity were fabricated in this study by additive manufacturing and foaming processes using polymethyl methacrylate (PMMA) and polyurethane foam (PUF), respectively. PMMA creates the macroscopic pores with triply periodic minimal surface (TPMS) structures, while PUF forms microscale porosity interpenetrating within the scaffolds, which has been confirmed by SEM and CT tests. Mechanical testing and finite element analysis (FEA) demonstrated significant enhancements in peak strength, toughness, and energy absorption of the IPCs compared to the scaffold alone, with increases of 134%, 73%, and 236%, respectively. The FEA provided insights into the failure and strengthening mechanisms of the interpenetrating porous structure. The continuous PUF component integrated within the IPCs effectively facilitated stress transfer, impeded crack propagation, and significantly prolonged the stress plateau of the scaffolds. Meanwhile, the PMMA primarily served as the main mechanical load-bearing component, transferring stress to the PUF during the deformation stage, resulting in a highly uniform stress distribution within the scaffolds. This uniform stress distribution creates an environment conducive to effective stress stimulation of the internally growing tissue.
Probabilistic investigation of piezoelectric application for reliability enhancement of composite laminates under edge delamination
Ali Delbariani-Nejad, Yi Xiong
doi:10.1016/j.compstruct.2024.118528
边缘剥落下压电材料增强复合材料层合板可靠性的概率研究
In this research a novel probabilistic numerical approach is developed to investigate the effectiveness of piezoelectric (PZT) to enhance the reliability of composite laminates under edge delamination onset (EDO). To achieve this, finite element (FE) modeling is employed as an implicit limit state function (LSF) based on a quadratic failure criterion and critical length concept. Then, an interactive interface that integrates FE analysis and reliability analysis is established to execute them simultaneously until the convergence condition of the reliability index is satisfied. To verify current FE analysis, the interlaminar stress peaks, and resulting edge delamination probability obtained in this study are compared with available data. Subsequently, the probability of EDO in angle-ply composite laminates under applied longitudinal strain and applied electric field on the PZT layer is assessed using both the first-order reliability method (FORM) and the second-order reliability method (SORM). The Monte Carlo simulation (MCS) is employed to verify the numerical results. Findings reveal that employment of PZT reduces EDO probability. Moreover, as the applied voltage increases, the critical strain required for definite EDO also enhances, and the positive influence of PZT on enhancing reliability becomes more pronounced, particularly with increased thickness under higher applied strain.
The structural design of an efficient heat conduction channel is critical for heat dissipation in electronic packaging material. The build of oriented boron nitride nanosheet (BNNS) network inside polymers has attracted much attention due to its excellent thermal conductivity and dielectric properties. However, to fabricate a BNNS/polymer composite, complex method and low thermal conductive resin for binding BNNS network are commonly involved, which severely restrict its facile production and enhancement in thermal conductivity. Herein, by utilizing para-aramid nanofibers (PANF) as assistance to BNNS to form thermal conduction network, we obtained high performance composite boards with good formability and adjustable sizes via a simple compression moulding of the BNNS/PANF aerogels. The composite boards exhibit a remarkable in-plane thermal conductivity of 10.62 W/m K−1 at 50 wt% BNNS loading, outstanding practical thermal management capability, excellent thermal stability, low dielectric constant and loss, showing great potential for electronic packaging applications. This facile construction strategy provides a feasible way for the large-scale production and application of high-performance thermal management materials in the future.
Integrated design of flame retardancy, smoke suppression and structure of carbon fiber reinforced vinyl ester resin composites through intercalation of nanofiber membranes
Mingming Yu, Yuji Chu, Wang Xie, Lin Fang, Liying Zhang, Musu Ren, Jinliang Sun
doi:10.1016/j.compstruct.2024.118531
通过嵌入纳米纤维膜对碳纤维增强乙烯酯树脂复合材料的阻燃、抑烟和结构进行一体化设计
A novel flame-retardant method based on the intercalation of nanofiber flame-retardant membrane has been studied for composite laminates. Compared to traditional additive flame-retardant method, this method is more efficient, does not affect the composite forming process, and can improve the mechanical properties of composite. Nanofiber flame-retardant membranes (FPm) are prepared from polyether sulfone (PES) and pentaerythritol phosphate ester (PEPA) by electrospinning technique and inserted in the interlayer of carbon fiber reinforced vinyl ester resin (CF/VER) composites. The FPm can improve the flame-retardancy and smoke suppression of the CF/VER composites by promoting the charring of interlayer structure and form a barrier layer. The thickness of the FPm and the flame-retardant performance of the composites are positive correlation. At a FPm’s thickness of 50 μm, the limiting oxygen index (LOI) and UL-94 ratings of the CF/VER composites reached 33.5 % and V-1, respectively. The total heat release (THR) and total smoke release (TSP) are reduced by 26.4 % and 30.4 %, respectively. Due to the interlayer enhancement effect of FPm, the mechanical strength and interlaminar fracture toughness of CF/VER composites are also improved. Especially, when the thickness of FPm is 30 μm, the mode I interlaminar fracture toughness (GIC) of the CF/VER composite increased by 17.4 %. while the flexural strength, interlayer shear strength (ILSS), mode II interlaminar fracture toughness (GIIC) and storage modulus (E’) are all enhanced.
Composites Part A: Applied Science and Manufacturing
Deep learning-based microstructure analysis of multi-component heterogeneous composites during preparation
Haozhen Li, Chong Wei, Zixiong Cao, Yi Zhang, Xiaoqiang Li
doi:10.1016/j.compositesa.2024.108437
基于深度学习的多组分非均相复合材料制备过程微观结构分析
Monitoring microstructure evolution during the preparation has always been a difficult problem in the modification studies of SiC composite matrix. Here, we used X-ray tomography microscopy to observe the microstructure of SiCf/SiC-W-ZrB2 composites at different fabrication stage. Based on deep learning, the tracking of the densification process of matrix-modified SiCf/SiC composites was achieved and its suitability for microstructure reconstruction was also verified. The results showed that the average errors of reconstructed SiCf/SiC, pore and Metal (W/ZrB2) are respectively 7.53%, 8.31% and 0.96% by comparison with the segmentation results. Compared with the experimental results, the average error and the average relative error of reconstructed SiCf/SiC is less than 3% and 3.74%.
Research on ultrasonic-stationary shoulder assisted friction stir lap welding of thermoplastic polymer and aluminum alloy
Kang Yang, Shuaiqiang Nian, Shude Ji, Wei Hu, Jinglin Liu, Lin Ma
doi:10.1016/j.compositesb.2024.111797
热塑性聚合物与铝合金的超声-静肩辅助搅拌摩擦搭接焊研究
Friction stir lap welding (FSLW) has advantages on obtaining dissimilar upper polymer and lower aluminum materials joint (polymer/Al joint), and how to heighten the bearing capacity of polymer/Al joint as much as possible is greatly meaningful for the manufacturing industries. In this study, choosing dissimilar polyamide 6 (PA 6) polymer and 6061-T6 aluminum alloy materials as research object, traditional FSLW, stationary shoulder assisted FSLW (SSFSLW) and ultrasonic-stationary shoulder assisted FSLW (U-SSFSLW) processes were compared to understand the mechanism of ultrasonic enhancement on the polymer/Al joint. Firstly, the surface morphologies were studied. Then the analyses of micro/macro-structures, mechanical properties and fracture features were carried out by optical microscopy, scanning electron microscopy, differential scanning calorimetry, X-ray diffraction and tensile tests. Results showed that the lap shear failure load of polymer/Al joint by U-SSFSLW reached 1502 N from 814 N by traditional FSLW, because the addition of ultrasonic avoided the bulged-nodule structures on top surface and the cavity defect in stir zone (SZ), broke the Al anchor in upper plate, enlarge the width of SZ in lower plate, and made the deeper micro-pits and larger dents at the interface between SZ bottom and lower plate. The U-SSFSLW process provides an effective way to fabricate the high-strength hybrid joint of dissimilar upper polymer and lower Al materials.
Analysis of factors influencing GFRP shredding energy consumption and the physical properties of the resulting recyclates
Shuai Cheng, Nai Yeen Gavin Lai, Kok Hoong Wong
doi:10.1016/j.compositesb.2024.111805
影响玻璃钢粉碎能耗及回收物物理性能的因素分析
Glass fibre reinforced polymer (GFRP) remains the dominant composite produced globally due to its low cost, high specific mechanical properties and chemical resistance performances. These unique features, however, impose significant recycling challenges for their end-of-life parts. Although there are various recycling technologies available, all of them require the waste GFRP to be reduced in size in order to enhance the recycling process efficiency. In this work, a full factorial design analysis was conducted to identify factors that influenced specific shredding energy consumption, average physical size and resin content of shredded GFRP recyclates. Factors investigated were glass fibre fabric architecture in GFRP wastes (non-crimp and nonwoven), GFRP waste feed rate (10-60 kg/hr) and screen aperture of the shredding process (6-20 mm). It was observed that specific shredding energy was not significantly affected by the fabric architecture but could be reduced by opting for larger screen aperture and/or lower feed rate. However, improvement to shredding energy efficiency was achieved if 6mm diameter screen was selected together with 60 kg/hr feed rate. The 60 kg/hr feed rate was found to be ideal in reducing oversize recyclates content but did not affect the median particle size of the remaining recyclates, which was found to be influenced by screen aperture and fabric architecture. Resin-rich and fibre-rich fractions were identified from the recyclates. The resin content of the former was found to be sensitive to all the studied factors.
A bidirectional-modification strategy for enhancing the reliability of thermoplastic-metal hybrid joint from atomic-scale
Yifan Liu, Jianhui Su, Xinbo Wang, Yunhua Deng, Caiwang Tan, Bo Chen, Xiaoguo Song, Swee Leong Sing
doi:10.1016/j.compositesb.2024.111795
从原子尺度提高热塑性金属杂化接头可靠性的双向改性策略
In this study, a strategy towards thermoplastic-metal hybrid joint via bidirectional modification for high reliability was designed. The chemical bond behavior and conditions at the interface were explored from atomic scale using density functional theory (DFT) calculation. Based on the bonding mechanism, the AZ31B alloy was oxidized and the carboxyl groups (COOH) were introduced in the resin chain to improve the strength of chemical bond. The mechanical property of the designed joint was significantly improved and the tensile-shear strength achieved 22.7 MPa after bidirectional modification, reaching 4.5 times that of untreated joints. It was mainly attributed to the generation of metal-carboxylate bridging complex—a typical strong coordination bond formed between two O atoms in COOH and two diagonal magnesium atoms in MgO. Experimental evidence also suggested the generation of new chemical bond at the CFRTP/AZ31B interface. Finally, the bidirectional modification was proved to be an efficient and reliable method with high industrial adaptability. The current work opened up a novel direction for reliability promotion of thermoplastic-metal hybrid structures.
Combined Loading of Unreinforced and Z-Pin Reinforced Composite Pi Joints: An Experimental and Numerical Study
James G. Finlay, Anthony M. Waas, Jonathan Bartley-Cho, Nav Muraliraj
doi:10.1016/j.compositesb.2024.111796
未加筋与z销加筋复合Pi节点的联合载荷:试验与数值研究
Blind predictions of experimental responses of non-reinforced and z-pin reinforced composite pi joints were established using a progressive damage and failure model. The finite element model used a novel mixed-mode cohesive formulation to model intra-laminar and inter-laminar damage. A deliberate meshing strategy was used for cohesive interlayers to capture the interaction between intra- and inter-laminar damage modes. A smeared cohesive zone modeling approach was implemented to efficiently include the effects of z-pinning for the z-pin reinforced specimens. Using material properties obtained through experimental correlation of simpler joint configurations, blind predictions for large element specimens subjected to combined loading (axial compression and push-off loading) were established. To assess the predictive capabilities of the model, experimental and numerical comparisons were made in terms of load-displacement response, critical loads, and failure progression. Comparisons between the experimental results and predictions for the unreinforced joints were found to be in good agreement across the range of compressive loads tested. For the z-pin reinforced joints, initial responses were accurately predicted; however, ultimate loads and the toughening effect of the z-pin reinforcement was overpredicted.
Pyrolysis process and products characteristics of glass fiber reinforced epoxy resin from waste wind turbine blades
Bolin Zhang, Shengen Zhang, Zeyu Yang, Weisheng Liu, Boyu Wu, Mingtian Huang, Bo Liu
doi:10.1016/j.compositesb.2024.111803
废风电叶片玻璃纤维增强环氧树脂热解工艺及产物特性研究
The installed wind power capacity has reached up to 906 GW globally meaning the usage of wind turbine blades (WTBs) with around 9.06 Mt. The waste WTBs with a rapid growth was estimated to be 72.0 kt in 2022 based on the projected lifetime of 20 years. The recycling of fibers reinforced thermoset polymer from waste WTBs has become a knotty environmental issue. This work aimed at studying the pyrolysis behaviors of a glass fibers reinforced epoxy resin materials from a waste WTBs, and revealing the impacts of pyrolysis atmosphere and temperature on the pyrolysis products. It was found that the black glass fibers with deposited carbon and the clean glass fibers were obtained by pyrolysis in N2 and air, respectively. Both pyrolysis in N2 and air produced the pyrolysis oil and gas with similar compositions. The preferable strength of fibers and yield of oil could be obtained at applicable pyrolysis temperature of 450 °C. The oil yields were 13.17 wt.-% and 11.93 wt.-% by pyrolyzing at 450 °C in N2 and air, respectively. The analysis of pyrolysis pathway suggested that the oxygen promoted the decomposition of epoxy resin into small molecules of gases by pyrolysis in air. The utilization of recycled products gas was also discussed. The findings of this work could provide some suggestions to explore a route with low cost to recycling the waste WTBs by pyrolysis.
Fragmentation effect of solvent in recovery of unsaturated polyester resin and its composites
Wenli An, Yan Zhang, Junyan Li, Shun Zhang, Chengfeng Shen, Xuehui Liu, Zhishan Su, Shimei Xu, Yu-Zhong Wang
doi:10.1016/j.compositesb.2024.111804
溶剂在回收不饱和聚酯树脂及其复合材料中的破碎效应
As the most productive thermosetting polymer, unsaturated polyester resin (UPR) and its composies were difficult to be chemcycled due to the mass transfer barrier in dense network structure. High temperature/pressure and mechanical crushing were usually applied to improve the mass transfer during chemcycling processes, but at the sacrifice of reaction selectivity and fiber integrity. Here, a unique fragmentation effect of aprotic solvents was observed in UPR, which is a non-reactive solvation that has the potential to replace mechanical fragmentation and improve the recyclability of UPR and its composite materials. The solvation was found to be based on the hydrogen bond between the solvent and ester group of UPR through Hansen solubility parameters and molecular dynamics simulation. It was the intermolecular force between the polyester clusters of UPR that was destroyed, leading to the fragmentation of UPR into micron-sized powder. The fragmentation effect is also applicable to other ester-containing polymers and provides a simple, facile, and energy-efficient method for the chemcycling of thermosetting resins, as well as direct exfoliation of reinforced fillers.
Induction heating of unidirectional C/PAEK – A thermographic study on eddy current formation
Y.M. Buser, E.T.M. Krämer, R. Akkerman, W.J.B. Grouve
doi:10.1016/j.compositesb.2024.111789
单向C/PAEK的感应加热——涡流形成的热成像研究
Induction welding is an attractive assembly method for carbon fibre reinforced thermoplastic composites. Parts are heated through the electromagnetic induction of eddy currents in the electrically conductive network of carbon fibres. Such networks rely (partly) on interlaminar contact incidence between the carbon fibres for unidirectional ply-based composites, rendering eddy current formation stochastic. The present study aims to visualise this stochastic behaviour in order to gain deeper insights into the formation of eddy currents. To this end, various laminates were induction heated using a stationary coil while monitoring the heating patterns using a thermal camera. Similar behaviour was then replicated on ply-scale specimens using a strong direct current. The recorded thermograms highlight that eddy currents are predominantly induced along the different fibre directions present in the lay-up. Moreover, it was demonstrated that ply interfaces have a substantial impact on the (re)distribution of current density within the plies.
Elastomer-based Soft Syntactic Foam with Broadly Tunable Mechanical Properties and Shapability
Akanksha Pragya, Natalie Young, Tushar K. Ghosh
doi:10.1016/j.compositesb.2024.111794
具有广泛可调力学性能和可塑性的弹性体软泡沫
Fabrication of lightweight composites using thermally responsive expandable microspheres (EM) embedded in an elastomeric matrix to form syntactic foams offers significant opportunities to create functional and structural composites for diverse applications. The morphology of the EM-elastomer composite on the micro- and macro-scales is significantly influenced by the fabrication sequence and parameters (composition, expansion time/temperature, etc.). Herein, we report the morphological evolution of an EM-elastomer composite through the fabrication processes and elucidate the interaction of relevant fabrication parameters. Unlike the majority of published reports on hard EM composites, the in-situ expansion of the closed-cell foam structure within a soft matrix leads to larger void sizes, and the concomitant expansive force of the EM impacts the polymer chain mobility within the soft composite. At the same time, higher EM loading improves the mechanical properties; the evolved microstructure leads to a lightweight but stiff structure. For the first time the report details the thermal expansion of EM under applied pretension, leading to irreversible prestrain-dependent morphological changes toward anisotropic mechanical properties. Additionally, the composites are shaped under constrained expansion. The study provides a comprehensive guide and expands the pathways for the practical application of EM-embedded soft syntactic foams in aerospace, electronics, wearables, robotics, etc.
Laser-assisted thermoplastic composite automated placement method has been applied to the molding of composites due to its advantages of fast molding speed and high heating efficiency. This study focuses on designing a robot for laser-assisted thermoplastic composite automated fiber placement, employing a modular approach to create a versatile fiber placement head. Control functions, such as electrical circuits, a computer interface, and tension control, were developed. Hybrid laminates, combining GF/PP unidirectional and braided composites, were manufactured by independently adjusting laser power (275 W ∼ 400 W) and compression force (150 N ∼ 400 N). Bonding properties were analyzed using wedge peel tests and microscopic detection, revealing superior toughness in laser-assisted laminates compared to autoclave counterparts. Altering laser power and compression force impacted polypropylene resin distribution, influencing hybrid interlayer peel strength. The inclusion of braided materials and elevated mold temperature proved effective in minimizing lamination warpage in GF/PP laminates.
激光辅助热塑性复合材料自动贴片法因其成型速度快、加热效率高等优点，已广泛应用于复合材料的成型。本研究的重点是设计一个激光辅助热塑性复合材料自动纤维放置机器人，采用模块化方法创建一个多功能纤维放置头。控制功能，如电路、计算机接口和张力控制，被开发出来。混合层压板，结合了GF/PP单向和编织复合材料，通过独立调节激光功率(275 W ~ 400 W)和压缩力(150 N ~ 400 N)制造。使用楔形剥离测试和显微检测分析了粘合性能，与高压灭菌器相比，激光辅助层压板具有优越的韧性。改变激光功率和压缩力会影响聚丙烯树脂的分布，影响杂化层间剥离强度。事实证明，在GF/PP层压板中加入编织材料和提高模具温度可以有效地减少层合翘曲。
CREEP ASSESSMENT OF THERMOPLASTIC MATERIALS FOR NON-STRUCTURAL COMPONENTS IN MARINE ENGINES
Jacopo Bardiani, Serena Bertagna, Luca Braidotti, Alberto Marinò, Vittorio Bucci, Claudio Sbarufatti, Andrea Manes
doi:10.1016/j.compositesb.2024.111800
船用发动机非结构部件用热塑性材料的蠕变评定
The substitution of metals with fiber-reinforced polymers represents a well-established practice in the automotive and aerospace industries, driven by advantages such as cost reduction, weight savings, and environmental benefits. In the marine engineering sector, there is a growing interest in this metal replacement trend, particularly for non-structural components of marine engines that can be produced by adopting proper fiber-reinforced thermoplastic polymers. However, evaluating the suitability of such materials for marine applications necessitates a thorough understanding of their creep behavior, given the demanding operational environments and strict safety standards. The material selection process must intricately consider the material's susceptibility to creep through tailored material design methodologies. Moreover, redesign activities should aim to leverage the material's creep-resistant properties while ensuring adequate strength and simplifying installation procedures. Unfortunately, unlike the automotive industry, testing innovative plastic components in real environments on working engines is quite impossible. Neither engine manufacturers nor owners would allow jeopardizing their machinery by installing technologies not yet certified in a delicate environment such as a ship’s engine room. In this context, finite element simulations offer a valuable tool to assess the material's creep performance and validate the proposed design when experimental measurements cannot be performed, hence predicting the component behavior over its intended lifetime. This study aims to exploit finite element analysis to evaluate the creep behavior and suitability for marine engine applications of a fiber-reinforced thermoplastic material, focusing on a camshaft cover of a four-stroke marine engine currently manufactured from aluminum alloy. Through numerical simulations, a commercial 30% wt GFs/PA6,6 thermoplastic composite emerges as a promising candidate, demonstrating adequate creep resistance while significantly reducing weight, processing costs, and energy consumption. The results obtained from the present study lay the foundations for the adoption of such material-based technology also in the marine engine sector despite the difficulties coming from the peculiarities of this industry.
Bamboo belts with variable fiber cell angles for winding applications: development of a novel manufacturing technique and assessment of performance feasibility
Qin Su, Yuting Yang, Yuanhai Zhang, Wei Song, Yu Luan, Benhua Fei, Huanrong Liu, Hu Miao, Xinxin Ma, Changhua Fang
doi:10.1016/j.compositesb.2024.111806
卷绕用可变纤维细胞角度竹带:一种新型制造技术的开发和性能可行性评估
In response to the environmental impacts of synthetic fiber production and disposal, coupled with limitations in the existing continuous processing methods for plant fibers, this study proposed a novel manufacturing approach for preparing wide and continuous bamboo winding belts. The current application scenarios of bamboo belt winding products are limited because the reinforcement orientation cannot be optimized due to the inherent stiffness of bamboo belts, and the variety of bamboo belt types is limited. This study employed two representative types of bamboo belts: bamboo slivers and thin bamboo veneers, which had varying cross-sectional aspect ratios. Verification demonstrated that this method enabled the production of bamboo winding products with any reinforcement orientations ranging from 0 radians to radians. This addressed the challenge of optimizing reinforcement orientation in bamboo winding products and was anticipated to broaden the application of this method to other winding units with unidirectional reinforcement. Additionally, the performance feasibility of the two bamboo winding belts prepared using this method was evaluated in terms of microstructure, surface wettability, and mechanical properties. The bamboo slivers and thin bamboo veneers, with their rigid-flexible structure, hydrophilicity, and non-catastrophic fracture characteristics, enhanced their winding potential. These wide, continuous, and rigid-flexible features of the bamboo winding belts held promise for their expanded applications in bamboo winding products, thus promoting sustainable and environmentally friendly manufacturing practices.
Aerogels are characterized with unique morphology and physical properties, thus are serving as essential elements in advanced applications. Nowadays, the delicate intelligent devices are frequently exposed in harsh environments, leading to multiple issues during application of functional aerogels including the limited resistance to extreme temperatures, requiring encapsulation prior to usage, and accumulation of Joule heat. In this study, we fabricated a multilayered aramid nanofiber (ANF)/MXene aerogel with the layer-by-layer stacking ANF and ANF/MXene layers. Attributing to the multilayered and porous structure, the aerogel displayed proper EMI shielding performance which maintained stable in harsh environments of excessive high temperature (200 °C) and low temperature (−196 °C). More importantly, obvious anisotropy in electrical conductivity (∼8 orders of magnitude) and thermal insulation (ΔT = 32 °C) was obtained along the in-plane and out-of-plane directions. As two demonstrations of potential applications, the sensing performance and thermal insulating property of the ANF/MXene aerogel was displayed. Inspiringly, the aerogel sensor exhibited significant durability and notable sensitivity to different deformations. Also, the aerogel displayed rapid heat dissipation along the in-plane direction while efficient thermal insulation along the out-of-plane direction, thus, can be applied in thermal management to protect the electronic devices. Therefore, the as-prepared ANF/MXene aerogel can serve as EMI shielding parts, encapsulation-free flexible electronics as compression sensor and anisotropic thermal insulator, which has great potential in the application of intelligent devices.
MXene grafted porous carbon cloth with alumina for high thermal conductivity and EMI shielding effect
Wondu Lee, Munho Kim, Jooheon Kim
doi:10.1016/j.compscitech.2024.110834
氧化铝接枝MXene多孔炭布具有高导热性和电磁干扰屏蔽效果
Thermal interface material (TIM) has a great potential for efficient heat management and safety of electronic devices. However, achieving high performance polymer-based TIM is still challenging because of its intrinsic thermal conductivity and weak mechanical properties. In particular, electromagnetic interference shielding effect (EMI SE) of polymer-based composites has a great attraction according to electronic devices have become ubiquitous, playing integral roles in everyday life in our increasingly interconnected world. Herein, a porous carbon cloth (CC) for use as a continuous thermally and electrically conductive template is prepared via a freeze-casting method, after which mxene (MX) is chemically grafted onto the CC surface. Then, the as-prepared MX-CC is used along with alumina (AO) to fill a poly vinyl alcohol (PVA) matrix in order to fabricate a thermally conductive film with electromagnetic interference (EMI) shielding properties. The resultant composite demonstrates remarkable characteristics, including an excellent EMI shielding effect of 28 dB, substantial tensile strength of 19 MPa, and impressive out of plane thermal conductivity (3.98 W/mK). When applied to a light-emitting diode (LED), the PVA/MX-CC/AO composite effectively manages heat, thereby resulting in a 49 °C reduction in the operating temperature. Therefore, the composites developed herein hold great promise for improving thermal management in electronic devices.
Revealing the failure mechanism of 2D triaxially braided composites under off-axial tension through mesoscale simulations
Yinglong Cai, Zhenqiang Zhao, Peng Liu, Jun Xing, Chao Zhang
doi:10.1016/j.compscitech.2024.110838
通过中尺度模拟揭示了二维三轴编织复合材料在离轴拉伸作用下的破坏机理
The external load angle is known to have a significant influence on the mechanical behavior of two-dimensional triaxially braided composites (2DTBCs). However, the experimental data for 2DTBCs under off-axial loading provide limited information for understanding the failure mechanisms. In this study, a comprehensive mesoscale finite element (FE) model for simulating 2DTBC specimens was established to evaluate the mechanical responses and damage characteristics when off-axial tensile loads are applied. The FE model effectively captured the mechanical response at five distinct angles (0°, 30°, 45°, 60°, and 90°) and revealed the evolving patterns of failure behavior, damage morphology, and out-of-plane deformation mechanisms corresponding to the different loading angles. The findings indicate that, when the external load aligns with the axial fiber bundle direction, the primary failure mechanism involves the fracture of load-bearing fiber bundles. In contrast, deviations from the axial loading direction resulted in failure that was primarily due to the undulation of the bias fiber bundles, resulting in a loading angle–dependent warping at the edge of the specimen due to local shear stress concentration. The findings of this study provide valuable insights that can inform the design of structures with improved application.
The design of carbon fiber (CF)-reinforced polyetheretherketone (PEEK) composite materials with suitable interfaces has consistently been challenging. In this study, we sulfonated poly (phthalazinone ether sulfone ketone) (PPESK) and PEEK to prepare water-soluble SPPESK and SPEEK. Subsequently, we prepared a water-soluble sizing agent (SPPESK/SPEEK) via a straightforward blending process. This sizing agent tended to accumulate randomly on the surfaces of CFs, forming a thin film with a heterogeneous structure in the nanoscale. At the molding temperature of the composite material, the two components on the fiber surface exhibited different rheological behaviors, with PEEK preferentially infiltrating the SPEEK region, forming strong molecular entanglements. Meanwhile, the SPPESK region provided a rigid supportive structure, offering the potential for the mechanical interlocking of PEEK in the interface layer. The performance of the prepared composite materials was significantly enhanced, with their interlaminar shear strength and flexural strength reaching 87.1 MPa and 975.8 MPa, respectively. With respect to those of commercial fiber-reinforced PEEK composites, an 89.8 % increase in interlaminar shear strength and a 79.39 % increase in flexural strength were observed. This interface reinforcement mechanism presents a universally applicable strategy for the future development of fiber-reinforced composite materials.
Protective Coating Performance for Structural Integrity of Polymer Composites in Fire: Novel Bench Scale Instrument Design and Coupon Level Test
Xiang Ao, Junchen Xiao, Gloria Guerrero Muñoz, Carlos González, De-Yi Wang
doi:10.1016/j.compscitech.2024.110830
火灾中聚合物复合材料结构完整性防护涂层性能:新型台架仪器设计与试验
The loss of structural integrity of fiber-reinforced polymer composites (FRPs) when set on fire poses a great threat for the safety of occupants and property, which can be alleviated by introducing fire protective methods. The fire-protective polymeric coating has shown great potential in reducing fire hazards of FRPs and preventing loss of post-fire mechanical properties, but it has seldom been proven to have a protective effect under simultaneous loading and fire damage on a coupon level using a lab scale instrument. In this work, a machine which can be mounted on the widely acknowledged cone calorimeter (CCT) was designed and fabricated with details provided. Two types of laminate were prepared to be subjected to a static axial or off-axial load while set ignited and burned. Results showed that the protective polymeric coating delayed coated coupons for mechanical failure time by more than 190% compared to coupons without any coating. With this instrument being universally adaptable to various types of CCT, it provided meaningful information to the materials design process of fire-safe FRPs.
Self-healing and thermal transport behavior in catalytic vitrimer-graphene composite
Md. Sherajul Islam, Jonghoon Lee, Vikas Varshney, Dhriti Nepal, Ajit K. Roy
doi:10.1016/j.compscitech.2024.110835
催化玻璃体-石墨烯复合材料的自愈和热输运行为
Vitrimers are a distinct category of polymers that could conduct dynamic cross-linking in response to temperature stimuli. In this work, using a molecular dynamics simulation model, we explore self-healing and the thermal transport behavior of vitrimer-graphene composites to overcome its inherent slow self-healing process. The temperature-dependent reversible cross-link mechanisms, which possess the capacity to dynamically modify the mechanical properties of these substances, are studied by explicitly integrating the temperature-dependent reaction probabilities. This modeling approach efficiently predict the changes in the mechanical properties of vitrimers when undergoing temperature cycling both above and below the topological freezing point, as well as the damage healing and subsequent recuperation of mechanical behaviors. The heat transport behavior of the graphene-vitrimer composite is investigated using non-equilibrium molecular dynamics in conjunction with self-healing models. The thermal conductivity of vitrimer-graphene composites, calculated by including a bilayer graphene sheet with varied flake size and interlayer spacings, exhibits a considerable enhancement as compared to standalone vitrimers. Notably, the thermal conductivity is subject to change when the separation distance changes. These results shed light on the self-healing and heat transmission in vitrimer and open the door to possible applications in several fields, including electronics, energy efficiency, aerospace, and materials research.
Recently, metamaterial absorbers (MAs) with a multi-layered anisotropic substrate have received significant attention due to their huge potential for application in major engineering fields like aircraft stealthing, electromagnetic sensing, and materials processing, etc. However, the working mechanism of this type of structural materials has not been well-understood yet, as the classical equivalent circuit model was only proposed to describe the conventional overall isotropic metal-substrate MAs. In this paper, for the first time, a generalized equivalent circuit model that considering the anisotropy of the multi-layered substrate is constructed, based on new findings about the unique distribution of the induced current inside the MA with a carbon fiber reinforced polymer (CFRP) composite substrate – a typical multi-layered anisotropic laminate. The effectiveness of the generalized analytical model is validated by predicting the structure-performance relationship of the CFRP-substrate MA, which is in excellent agreement with numerical simulation results based on Maxwell’s equations. Experimental cases have also been conducted to demonstrate the strong power of this model in inverse design of several tunable MAs. Through the above research, the scope of the equivalent circuit modelling has been greatly broadened, which can help to design a series of MAs with more extreme performance in future.
