今日更新:Composite Structures 4 篇,Composites Part A: Applied Science and Manufacturing 6 篇,Composites Part B: Engineering 3 篇,Composites Science and Technology 5 篇
Shear performance of GFRP reinforced UHPC short beams
Omar Salman, Farid Abed, Yazan Alhoubi
doi:10.1016/j.compstruct.2024.118637
GFRP增强UHPC短梁的抗剪性能
This paper investigated experimentally the shear performance of ultra-high-performance concrete (UHPC) deep beams reinforced longitudinally with glass fiber reinforced polymer (GFRP) bars without web reinforcements. Ten beams were cast, in which seven were longitudinally reinforced with GFRP bars, while the remaining three were reinforced with steel bars for comparison. All beams had similar lengths and widths of 2000 mm and 150 mm, respectively, while the depths varied. The test parameters included the effective depth (d), shear span-to-depth ratio (a/d), number of longitudinal bars, and longitudinal reinforcement ratio (ρ). All the GFRP reinforced beams had higher shear capacities and lower post cracking stiffness than their steel counterparts. The experimental results show that varying the test parameters have a significant impact on the shear capacity of the beams. For instance, decreasing the a/d ratio for the GFRP reinforced beams from 1.8 to 1.5 and from 1.8 to 1.1 increased the load carrying capacity by 33 % and 95 %, respectively. The experimental results for the shear capacity were compared against the predictions obtained using the strut and tie method as per the ACI-318–19 and CSA-S806-12 codes. The failure load predictions by the ACI and CSA code showed the same trends as those shown in the experimental results. Moreover, both codes were conservative in predicting the shear capacities.
本文对纵向无腹板加筋玻璃纤维增强聚合物(GFRP)筋的超高性能混凝土深梁的抗剪性能进行了试验研究。共浇筑10根梁,其中7根纵向采用GFRP筋加固,其余3根采用钢筋加固进行对比。所有梁的长度和宽度相似,分别为2000 mm和150 mm,但深度不同。试验参数包括有效深度(d)、抗剪跨深比(a/d)、纵筋数、纵向配筋率(ρ)。GFRP加固梁具有较高的抗剪承载力和较低的开裂后刚度。试验结果表明,改变试验参数对梁的抗剪能力有显著影响。例如,将玻璃钢加固梁的a/d比值从1.8降低到1.5和从1.8降低到1.1,其承载能力分别提高了33 %和95 %。将试验结果与ACI-318-19和CSA-S806-12规范的杆系法预测结果进行了比较。ACI和CSA代码预测的破坏荷载与实验结果显示的趋势相同。两种规范对抗剪承载力的预测均较为保守。
Multi-scale impact of geometric uncertainty on the interface bonding reliability of metal/polymer-based composites hybrid (MPH) structures
Wenfeng Pan, Lingyu Sun, Xudong Yang, Yiben Zhang, Jiaxing Sun, Jiachen Shang, Zhengqing Yang, ChengDong Xu
doi:10.1016/j.compstruct.2024.118640
几何不确定性对金属/聚合物基复合材料杂化结构界面键合可靠性的多尺度影响
Metal/polymer-based composites hybrid (MPH) structures combine the high strength of metals with the low density of polymer-based composites, making them widely used in automotive applications. However, the random characteristics of the microgeometry at the pretreated MPH interface have made it challenging to predict its interface bonding failure probability accurately and quickly. This paper presents an advanced FE2 prediction method for bonding performance of MPH interface based on multi-fidelity regression and artificial neural networks (ANNs). When compared to experimental fracture mechanics results for failure mode I and II, the prediction errors for peak loads are 3.9 % and 5.6 %, respectively. At same time, the computational efficiency is over 6 times higher than that of traditional FE2 methods. Additionally, how interface microstructure parameters affect the tensile/shear performance, crack initiation, and propagation directions are investigated at the micro-scale. Under combined tensile/shear loads, the propagation mechanisms of interface microgeometry uncertainties in MPH are revealed theoretically. An interface design method with a high adhesion probability is proposed, identifying high load-bearing areas within the feasible design domain under bending loads for MPH structures. This provides a quickly accessible parameter matching scheme during conceptual design, offering a theoretical foundation for the application of MPH structures in engineering fields.
金属/聚合物基复合材料混合(MPH)结构结合了金属的高强度和聚合物基复合材料的低密度,使其在汽车应用中得到广泛应用。然而,预处理后的MPH界面微观几何结构的随机性给准确、快速地预测其界面结合破坏概率带来了挑战。本文提出了一种基于多保真度回归和人工神经网络(ann)的复合材料界面键合性能FE2预测方法。与破坏模式I和II的断裂力学实验结果相比,峰值荷载的预测误差分别为3.9 %和5.6 %。同时,计算效率是传统FE2方法的6倍以上。此外,在微观尺度上研究了界面微观结构参数对拉伸/剪切性能、裂纹起裂和扩展方向的影响。在拉伸/剪切复合载荷作用下,从理论上揭示了MPH中界面微观几何不确定性的传播机理。提出了一种高粘接概率的界面设计方法,在可行设计域内确定MPH结构在弯曲荷载作用下的高承载区域。这为概念设计提供了一种快速获取的参数匹配方案,为MPH结构在工程领域的应用提供了理论基础。
Modified cure cycles for increased fatigue performance of fiber metal laminates
Johannes Wiedemann, Selim Mrzljak, Josef Koord, Christian Hühne, Frank Walther
doi:10.1016/j.compstruct.2024.118631
改进固化周期以提高金属纤维层压板的疲劳性能
Modified (MOD) cure cycles that deviate from the manufacturer’s recommended cure profile can reduce the inherent thermally induced residual stresses (TRS) in fiber metal laminates (FML). Literature shows that MOD cycles do not adversely affect the material properties but enhance the quasi-static material strength. However, the literature does not comprehensively discuss the impact of MOD cycles on material performance during cyclic fatigue loading. This paper, therefore, investigates how MOD cycles influence the fatigue characteristics of different FML layups made of carbon fiber-reinforced polymer (CFRP) and steel. The experimental results confirm that the quasi-static material strength and the modulus of the FML are increased when using MOD cure cycles. The evaluation of fatigue tests with digital image correlation, thermography, and electrical resistance measurements of notched specimens shows that a reduction of TRS delays damage initiation in the metal facesheets and decreases the crack growth rate until facesheet failure. The results further show that layup-dependent parameters, the maximum stress in the metal sheets, and metal sheet thickness significantly govern the evolution of fatigue damage. In summary, modified cure cycles are an efficient tool to enhance the quasi-static and fatigue performance of CFRP-steel hybrid laminates.
修改(MOD)固化周期,偏离制造商推荐的固化配置文件,可以减少固有的热诱导残余应力(TRS)在纤维金属层压板(FML)。文献表明,MOD循环不会对材料性能产生不利影响,但会提高材料的准静态强度。然而,文献没有全面讨论循环疲劳载荷下MOD循环对材料性能的影响。因此,本文研究了MOD循环如何影响碳纤维增强聚合物(CFRP)和钢制成的不同FML层的疲劳特性。实验结果表明,采用MOD固化循环可以提高FML的准静态材料强度和模量。通过数字图像相关、热成像和缺口试样电阻测量的疲劳测试评估表明,TRS的降低延迟了金属表面的损伤开始,降低了裂纹扩展速度,直到表面失效。结果进一步表明,铺层相关参数、金属板内最大应力和金属板厚度对疲劳损伤的演化具有显著的控制作用。综上所述,修正固化周期是提高cfrp -钢混杂层合板准静态和疲劳性能的有效工具。
Investigation on the energy absorption characteristics of novel graded auxetic re-entrant honeycombs
Zhao Zhang, Yiwen Gu, Hengan Wu, Qingpeng Chen
doi:10.1016/j.compstruct.2024.118633
新型梯度增氧重入式蜂窝吸能特性研究
In this work, innovative graded auxetic re-entrant honeycombs constructed by adjusting the geometric parameters of a core unit cell are proposed, and their deformation modes and energy absorption characteristics with different impact speeds are systematically investigated. The novel graded design utilizes structural hierarchy on the meso-scale and functional gradient on the macro-scale. The numerical simulation models are verified by comparing the experimental results. The results show that compared with the ungraded honeycomb (URH), one of the graded honeycombs (GRHs), named GRH1, can greatly improve the specific energy absorption by 36.4%, 10.8%, and 6.00% for the quasi-static, low, and high-speed impact at a strain of 0.6. At the same time, the initial peak stress of GRH1 is decreased by 43.2% and 27.1% compared with that of URH for low and high-speed impact, respectively. It could be indicated that the GRH1 was an ideal energy-absorbing structure. This work provides a new route for designing graded auxetic honeycombs with enough insight to understand the deformation mechanism of the structures, which could be used in lightweight buffer protective systems.
本文提出了一种通过调整核心单元格的几何参数构建的新型梯度减重蜂窝,并对其在不同冲击速度下的变形模式和能量吸收特性进行了系统研究。这种新型的分级设计在中观尺度上采用结构层次,在宏观尺度上采用功能梯度。通过与实验结果的比较,验证了数值模拟模型的正确性。结果表明:与未分级蜂窝(URH)相比,分级蜂窝(GRH1)在应变为0.6的准静态、低速和高速冲击下的比能吸收率分别提高了36.4%、10.8%和6.00%;同时,在低速和高速冲击下,GRH1的初始峰值应力分别比URH降低了43.2%和27.1%。由此可见,GRH1是一种理想的吸能结构。这项工作为设计渐变变形蜂窝结构提供了一条新的途径,并对结构的变形机制有了足够的了解,可以用于轻型缓冲保护系统。
Influence of the surface energy of a basalt fiber on capillary wicking and in-plane permeability of reinforcements
Romain Ravel, Monica Francesca Pucci, Pierre-Jacques Liotier
doi:10.1016/j.compositesa.2024.108496
玄武岩纤维表面能对增强材料毛细吸湿和面内渗透性的影响
This study evaluates the influence of a thermal treatment of a basalt fiber on capillary wicking tests and in-plane permeability experiments, under several pressure differences. The impact of the treatment was characterized at three scales: microscopic, to determine the fiber surface energy; mesoscopic, to estimate an equivalent capillary pressure ( P c a p ) of the fabric in spontaneous impregnation; and macroscopic, to determine the saturated ( K s a t ) and unsaturated ( K u n s a t ) permeability of the fibrous preform at the process scale. Results at the microscopic scale showed that the thermal treatment increased the polarity of the fiber by 22% and decreased its surface roughness. Capillary wicking tests showed that the treated fabric presents a better affinity with water, increasing P c a p by 68%. At the process scale, permeability experiments showed the increase of K s a t and K u n s a t after treatment. Finally, results of capillary pressure ( Δ P γ ) showed a dominance of capillary effects under the negative pressure difference.
本研究评估了几种压力差下玄武岩纤维的热处理对毛细管吸湿试验和平面渗透性试验的影响。对处理的影响进行了三个尺度的表征:微观的,以确定纤维的表面能;介观,估计织物在自发浸渍时的等效毛细管压力(P ca P);宏观上,确定纤维预制体在工艺尺度上的饱和(K sat)和不饱和(K unsat)渗透率。微观结果表明,热处理使纤维极性提高22%,表面粗糙度降低。毛细吸湿试验表明,经处理后的织物具有较好的亲水性,P - c - a - P提高68%。在工艺尺度上,渗透率实验表明,处理后的K s at和K u n s at均有所增加。最后,毛细管压力(Δ P γ)结果显示,在负压差下,毛细管效应占主导地位。
Analyses and control of interphase structures and adhesion properties of epoxy resin/epoxy resin for development of CFRP adhesion systems
Naho Aoki, Junpei Yamazaki, Takuya Matsumoto, Masayasu Totani, Atsuomi Shundo, Keiji Tanaka, Takashi Nishino
doi:10.1016/j.compositesa.2024.108511
环氧树脂/环氧树脂相间结构和粘接性能的分析与控制,用于CFRP粘接体系的开发
In the adhesion of carbon fiber reinforced plastics (CFRP), the boundary regions were composed of only epoxy resins of CFRP matrix and adhesives, and their similar epoxy structures pose significant difficulty in studying the adhesion mechanism. Herein, we focused on structure and properties of laminates of epoxy resin substrates and adhesives with different curing conditions of substrates. We prepared laminates using deuterated epoxy adhesives or fluorinated epoxy adhesives, and their boundary regions were identified through confocal Raman scattering measurements. The regions were distributed into “penetration” and “interphase”. In particular, the penetration phase is a key of the adhesion properties. The penetration behaviors strongly depended on the crosslinking densities of the adherends, suggesting that the penetration regions would be directly impacted by the curing conditions of the substrates and molecular size of epoxy adhesive precursors. Our findings provide insights into novel designs of the reliable adhesion-based manufacturing systems of CFRP.
在碳纤维增强塑料(CFRP)的粘接过程中,边界区域仅由CFRP基体的环氧树脂和胶粘剂组成,两者相似的环氧结构给粘接机理的研究带来很大困难。本文重点研究了不同固化条件下环氧树脂基板和胶粘剂的结构和性能。我们用氘化环氧胶粘剂和氟化环氧胶粘剂制备了层压板,并通过共聚焦拉曼散射测量确定了它们的边界区域。区域分布为“穿透”和“间期”。其中,渗透阶段是影响粘接性能的关键。渗透行为强烈依赖于胶粘剂的交联密度,表明基体的固化条件和环氧胶粘剂前驱体的分子大小直接影响渗透区域。我们的研究结果为可靠的CFRP粘接制造系统的新设计提供了见解。
Constructing house-of-cards-like networks with BNNS confined in interlocking Al2O3 platelet skeletons for thermally conductive epoxy composites
Fanjun Guo, Tao You, Kangle Xue, Jun Li, Li Liu, Yudong Huang
doi:10.1016/j.compositesa.2024.108513
在热传导环氧复合材料中,用限制在互锁Al2O3血小板骨架中的BNNS构建卡屋状网络
The construction of 3D filler networks is an effective strategy to improve the thermal conductivity of epoxy resins, yet it is still severely limited by the disconnection of conduction channels. In this contribution, an original interlocking hybrid skeleton with continuous conduction channels was developed by assembling BNNS into an in situ-formed interlocking Al2O3 platelet skeleton using commercial polyurethane as a template, where large intergranular contact areas of Al2O3 platelets were established by sintering to greatly decrease the contact thermal resistance. Besides, the interlocking Al2O3 skeleton coupled with BNNS under hydrogen bonding endowed further improvement of its thermal conductivity. The optimized Al2O3/BNNS/EP composite displayed an excellent thermal conductivity of 5.01 W/mK at 15.3 vol% of Al2O3 and 11.4 vol% of BNNS loading, far higher than that of neat epoxy resin by 1904.0 %. Meanwhile, the interlocking hybrid skeleton provided the epoxy resin with low dielectric loss, satisfactory thermal stability and flame retardancy.
三维填充网络的构建是提高环氧树脂导热性的有效策略,但其仍然受到导电通道断裂的严重限制。在本论文中,以商用聚氨酯为模板,将BNNS组装成原位形成的联锁Al2O3血小板骨架,开发了具有连续传导通道的原始联锁混合骨架,其中Al2O3血小板通过烧结建立了大的晶间接触区域,大大降低了接触热阻。此外,联锁Al2O3骨架与BNNS在氢键作用下耦合,进一步提高了其导热性。优化后的Al2O3/BNNS/EP复合材料在Al2O3含量为15.3 vol%和BNNS含量为11.4 vol%时的导热系数为5.01 W/mK,远高于纯环氧树脂的1904.0 %。同时,互锁的杂化骨架使环氧树脂具有低介电损耗、良好的热稳定性和阻燃性。
A multifunctional epoxy composites based on cellulose nanofiber/carbon nanotube aerogels: Simultaneously enhancing fire-safety, thermal conductive and photothermal performance
Jiali Yan, Miaojun Xu, Xinrui Hu, Lubin Liu, Xixi Xiao, Bin Li
doi:10.1016/j.compositesa.2024.108514
基于纤维素纳米纤维/碳纳米管气凝胶的多功能环氧复合材料:同时增强防火、导热和光热性能
As 5G technology develops and electronic power density increases, preparing epoxy resin (EP) composites with excellent fire-safety, thermostability, and thermal conductivity remains challenging. Herein, hexaphenoxy cyclotriphosphazene and poly(piperazine methylphosphonic acid pentaerythritol ester) were used as synergistic flame retardants (FR) for EP. The cellulose nanofiber/carboxylated multiwalled carbon nanotubes aerogels (CCA80) were prepared and immersed into the EP and FR mixture to obtain EP/CCA80/FR composites. Compared with neat EP, the limiting oxygen index of EP/CCA80/6 wt% FR increased by 38.9 %, the total heat release and CO2 production rate decreased by 30.61 % and 39.47 %, respectively, achieving the UL-94 V-0 rating. Moreover, its thermal conductivity was 1.06 W · m−1·K−1, 457.9 % higher than neat EP, while maintaining excellent electrical insulation. Its surface temperature maintained at 94.5 °C under 1.0 kW·m−2 irradiation for 2 h, exhibiting good photothermal conversion capability and photobleaching resistance. A novel fabrication methodology of multifunctional EP composites for high-performance electronic component was proposed.
随着5G技术的发展和电子功率密度的增加,制备具有优异防火安全性、热稳定性和导热性的环氧树脂(EP)复合材料仍然具有挑战性。本文采用六苯基环三磷腈和聚哌嗪甲基膦酸季戊四醇酯作为EP的协同阻燃剂(FR)。制备纤维素纳米纤维/羧化多壁碳纳米管气凝胶(CCA80),并将其浸入EP和FR混合物中,得到EP/CCA80/FR复合材料。与纯EP相比,EP/CCA80/6 wt% FR的极限氧指数提高了38.9%,总放热量和CO2产率分别降低了30.61%和39.47%,达到了UL-94 V-0等级。导热系数为1.06 W·m−1·K−1,比纯EP高457.9%,同时保持了良好的电绝缘性。在1.0 kW·m−2照射下,表面温度保持在94.5℃,具有良好的光热转换能力和抗光漂白性能。提出了一种高性能电子元件用多功能EP复合材料的制备方法。
Pulp fibre foams: Morphology and mechanical performance
Markus Wagner, Veronika Biegler, Sebastian Wurm, Georg Baumann, Alexander Bismarck, Florian Feist
doi:10.1016/j.compositesa.2024.108515
纸浆纤维泡沫:形态和机械性能
Cellulose (pulp) fibre foams serve as bio-based alternative to fossil-based cellular lightweight materials. The mechanical properties of cellulose fibre foams are inferior compared with traditional polymer foams and available information is often limited on compression properties. We present a comprehensive analysis of cellulose fibre foams with densities ranging from 60 to 130 kg/m3, examining their compression, tensile, flexural, and shear properties. Key findings include a high mean zenithal fibre angle which decreases with increasing density, as well as a high strain rate amplification (SRA) in compressive strength, which also decreases with increasing density. With respect to formulation, the addition of carboxymethyl cellulose (CMC) enhanced fibre dispersion, bubble homogeneity of the wet foam, and dimensional stability of the end-product.These results provide a foundation for numerical models and advance the understanding of cellulose pulp fibre foams, highlighting their potential for certain applications.
纤维素(纸浆)纤维泡沫作为生物基替代化石基细胞轻质材料。与传统的聚合物泡沫塑料相比,纤维素纤维泡沫塑料的力学性能较差,而且有关其压缩性能的信息往往有限。我们提出了纤维素纤维泡沫的密度范围从60到130 kg/m3的综合分析,检查他们的压缩,拉伸,弯曲和剪切性能。主要发现包括高平均纤维顶角随密度的增加而减小,以及抗压强度的高应变率放大(SRA),也随密度的增加而减小。在配方方面,羧甲基纤维素(CMC)的加入增强了纤维的分散性、湿泡沫的气泡均匀性和最终产品的尺寸稳定性。这些结果为数值模型提供了基础,并促进了对纤维素浆泡沫纤维的理解,突出了它们在某些应用中的潜力。
Vibro-acoustic Characterization of Functionally Graded Multiwalled Carbon Nanotube composite cylindrical panels: An experimental approach
R. Kiran Kumar Reddy, AR Veerappan, Nivish george
doi:10.1016/j.compositesa.2024.108518
功能梯度多壁碳纳米管复合圆柱形板的振动声学特性:实验方法
This study experimentally investigates the vibro-acoustic properties of Functionally Graded Multiwalled Carbon Nanotubes (FG-V MWCNT) Glass Fiber Reinforced Polymer composite cylindrical panels, a topic often explored through numerical methods. A novel process methodology is introduced to realize FG-V MWCNT composites, and the results are compared with those of uniformly distributed and conventional composites. Using an in-house developed experimental setup, the natural frequencies, mode shapes, acceleration, and Sound Pressure Levels (SPL) are measured. The FG-V MWCNT composites demonstrate a notable enhancement in fundamental frequency (21.13%) and a reduction in SPL in the lower frequency range compared to conventional composites. The proposed material composition and process methodology show potential for creating lightweight, structurally efficient large airframe components.
本研究通过实验研究了功能梯度多壁碳纳米管(FG-V MWCNT)玻璃纤维增强聚合物复合材料圆柱形板的振动声学特性,这是一个经常通过数值方法探索的主题。介绍了一种新的工艺方法来实现FG-V MWCNT复合材料,并与均匀分布和常规复合材料的结果进行了比较。使用内部开发的实验装置,测量固有频率、模态振型、加速度和声压级(SPL)。与传统复合材料相比,FG-V MWCNT复合材料的基频显著提高(21.13%),低频范围的声压级显著降低。所提出的材料组成和工艺方法显示出创造轻质、结构高效的大型机身部件的潜力。
A Pattern Design Strategy for Microwave-absorbing Coding Metamaterials with Tortuosity and Connectivity
Ruijiang Fan, Dawei Li, Wenhe Liao, Tingting Liu, Xiangjia Li, Tengteng Tang, Junming Zhao, Tian Jiang
doi:10.1016/j.compositesb.2024.111880
具有弯曲性和连通性的微波吸收编码超材料的模式设计策略
Microwave absorption presents a challenge for the design of metamaterials, which is critical for the stealth and electromagnetic compatibility. To address this, a novel design strategy for patterns is proposed to enhance the wave absorption, which is tortuosity and connectivity. Utilizing the carbon ink composite and genetic algorithm, multi-layer coding metamaterials (MCMs) are designed to satisfy diverse engineering specifications, with reflectivity tests confirming their efficacy. Temperature alternation experiments simulate frequent environmental changes, and the absorptivity of MCMs is compared to evaluate their resilience. This approach ensures the designed MCMs maintain performance and stability under variable thermal conditions, offering a robust solution for advanced applications.
微波吸收对超材料的设计提出了挑战,它对超材料的隐身性和电磁兼容性至关重要。为了解决这个问题,提出了一种新的图案设计策略来增强波的吸收,即扭曲度和连通性。利用碳墨复合材料和遗传算法,设计了多层编码超材料(mcm),以满足不同的工程要求,并通过反射率测试验证了其有效性。温度交替实验模拟了频繁的环境变化,并比较了mcm的吸收率来评估其弹性。这种方法确保设计的mcm在可变热条件下保持性能和稳定性,为高级应用提供了强大的解决方案。
Damage characterization and modelling of FRP laminated composites subjected to external edge-on impact
Nian Li, Jian Du, Hsiao Mun Lee, Weiling Liu, Yangyan Zheng, Heow Pueh Lee
doi:10.1016/j.compositesb.2024.111879
玻璃钢层合复合材料受外缘冲击的损伤表征和建模
This paper presents both experimental and numerical investigations into the edge-on impact behavior of T700/YPH307 composite laminates with varying lay-up designs and impact energy levels. Various non-destructive testing techniques, including visual inspection, ultrasonic C-scanning and X-ray computed tomography (CT), were used to detect the post-impact damage status and further reveal its 3D spatial distribution. A continuum damage mechanics (CDM) model, incorporating in-plane shear nonlinearity, fracture plane angle within anisotropic materials, as well as fiber kinking failure in longitudinal compression, was established using an explicit solver. Detailed comparison of the experimental and numerical results was conducted in mechanical response curves and failure mechanisms, where a good agreement was observed. Parameter analyses on the in-situ strengths and the friction coefficient were also performed, offering guidelines for the edge-on impact modelling. Failure mechanisms induced by edge-on impact typically exhibit two distinct features: a highly localized debris wedge, which can be regarded as a trigger in the subsequent occurrence of damage, and the bending fracture of the outer plies resulting from the wedge effect during the oscillating stage of an impact force plateau. Besides, higher impact energy exacerbated internal damage, while the influence of the lay-ups was relatively limited.
本文对不同铺层设计和冲击能级的T700/YPH307复合材料层合板的边对冲击性能进行了实验和数值研究。采用目视检测、超声c扫描和x射线计算机断层扫描(CT)等多种无损检测技术检测冲击后损伤状态,并进一步揭示其三维空间分布。利用显式求解器建立了考虑各向异性材料面内剪切非线性、断裂面角度以及纵向压缩下纤维扭结破坏的连续损伤力学模型。实验结果与数值结果在力学响应曲线和破坏机制上进行了详细比较,两者吻合较好。对原位强度和摩擦系数进行了参数分析,为边对冲击建模提供了指导。由正面撞击引起的破坏机制通常表现出两个明显的特征:高度局部化的碎片楔块,它可以被视为随后发生损伤的触发器,以及在冲击力平台振荡阶段由楔块效应引起的外层弯曲断裂。较高的冲击能加剧了内部损伤,而铺层对内部损伤的影响相对有限。
A novel rapid fabrication method and in-situ densification mechanism for ceramic matrix composite
Yijun Zhang, Yifan Xue, Yu Liu, Weijie Li, Kaiqiang Liu, Weijian Han, Zhongwei Zhang
doi:10.1016/j.compositesb.2024.111881
一种新型陶瓷基复合材料的快速制备方法及原位致密化机理
The extensive application of ceramic matrix composites has always been limited due to the long-period and expensive process. Hence, this research introduces a rapid manufacturing method named as ViSfP-TiCOP (High Viscosity Solvent-free Precursor Combined Elemental Titanium Controlled Pyrolysis). The solvent-free precursor possesses high viscosity (30°C, 106mPa·S) and wide molecular weight distribution (Mz/Mw=3.3), accomplishing stable loading of inorganic fillers. Simultaneously, the elementary titanium and ZrB2, as the active and inert filler, are dopped into the precursor to control the pyrolysis. The ViSfP-TiCOP technique offers a rapid method to manufacture CMCs under pressureless and low pyrolysis temperature conditions (1200°C). Comparing to the addition of ZrB2, the precursor with titanium provides an exceptional ceramic yield of 87wt%, leading a notable enhancement in the rate of densification. This high densification efficiency is attributed to an in-situ titanium gas-phase reaction, besides with the high degree of cross-linking and low volatile of precursor. After undergoing three cycles of impregnation-pyrolysis, the porosity of C/SiBCN-Ti was discovered to be below 10 Vol%, whereas that of C/SiBCN-25wt%ZrB2 still remained as high as 20.91 Vol%. The ViSfP-TiCOP technology can provide guidance for low-cost and rapid preparation of CMCs.
陶瓷基复合材料的广泛应用一直受到周期长、成本高的限制。因此,本研究引入了一种名为ViSfP-TiCOP(高粘度无溶剂前驱体组合元素钛控制热解)的快速制造方法。该无溶剂前驱体具有高粘度(30℃,106mPa·S)和宽分子量分布(Mz/Mw=3.3),可实现无机填料的稳定加载。同时,在前驱体中加入元素钛和ZrB2作为活性和惰性填料来控制热解。ViSfP-TiCOP技术提供了一种在无压力和低热解温度条件下(1200°C)快速制造cmc的方法。与添加ZrB2相比,钛前驱体的陶瓷产率高达87wt%,导致致密化率显著提高。这种高致密化效率主要归功于原位钛气相反应,以及交联度高、前驱体挥发性低。经过3次浸渍-热解循环后,发现C/SiBCN-Ti的孔隙率低于10 Vol%,而C/SiBCN-25wt%ZrB2的孔隙率仍然高达20.91 Vol%。ViSfP-TiCOP技术可为低成本、快速制备cmc提供指导。
Crushing behavior of GFRP composite-reinforced PVC tubes: Experimental testing and numerical simulation
Khaled Yousif, Aamir Dean, Elsadig Mahdi
doi:10.1016/j.compscitech.2024.110903
GFRP复合增强PVC管的破碎性能:实验测试和数值模拟
This paper introduces glass fiber reinforced polymer (GFRP)-reinforced Polyvinyl Chloride (PVC) tubes, both corrugated and non-corrugated, designed as energy absorber devices. The PVC tubes were externally and internally reinforced with GFRP composite oriented at ± 4 5 ∘ and subjected to quasi-static axial compression tests. Results indicated that all reinforced tubes exhibited significantly higher load-bearing capacity, energy absorption capability, and crushing force efficiency compared to standard PVC tubes. Among the tested specimens, externally reinforced corrugated tubes demonstrated the highest specific energy absorption (SEA), surpassing other configurations by 17.5 kJ/kg when considering both pre- and post-crushing stages combined. However, these corrugated specimens showed instability during crushing, reflected in poor instantaneous crush force efficiency (iCFE) and the lowest iCFE among the composite tubes, with an average decrease of 43.59%. The corrugation notably increased the initial peak load, enhancing energy absorption in the pre-crushing stage without compromising the stability of crush force efficiency (CFE). Additionally, the combination of external and internal reinforcement significantly improved CFE and iCFE. Consequently, the PVC tubes combining corrugation with both external and internal reinforcement emerged as the best-performing configuration among all tested tubes. Furthermore, a 3D Finite Element (FE) model was developed using ABAQUS FE code with user-defined subroutines to simulate the crushing process. The constitutive models and numerical procedures employed are detailed. The FE model’s predictions showed a satisfactory correlation with experimental results, providing valuable insights into the crushing mechanics and offering a predictive tool for future design optimizations.
本文介绍了玻璃纤维增强聚合物(GFRP)增强聚氯乙烯(PVC)波纹管和非波纹管作为吸能装置的设计。PVC管内外用GFRP复合材料加固,在±4.5°方向上定向,并进行准静态轴压试验。结果表明,与标准PVC管相比,所有增强管具有更高的承载能力、能量吸收能力和破碎力效率。在测试样本中,外部增强波纹管表现出最高的比能吸收(SEA),在考虑破碎前和破碎后阶段时,其比能吸收(SEA)超过其他配置17.5 kJ/kg。然而,这些波纹试件在破碎过程中表现出不稳定性,表现为较差的瞬时破碎力效率(iCFE),其iCFE在复合管材中最低,平均降低43.59%。波纹明显增加了初始峰值载荷,增强了预破碎阶段的能量吸收,但不影响破碎力效率(CFE)的稳定性。此外,外部和内部联合加固显著提高了CFE和iCFE。因此,PVC管结合波纹与外部和内部增强成为所有测试管中性能最好的配置。利用ABAQUS有限元软件建立三维有限元模型,并自定义子程序对破碎过程进行模拟。详细介绍了所采用的本构模型和数值计算方法。有限元模型的预测结果与实验结果具有令人满意的相关性,为破碎力学提供了有价值的见解,并为未来的设计优化提供了预测工具。
3D printing, leakage-proof, and flexible phase change composites for thermal management application
Siyuan Qiu, Yajiao Li, Yi An, Wenhao Wang, Yuanmin Chen, Ke Chen, Daming Wu, Jingyao Sun
doi:10.1016/j.compscitech.2024.110905
用于热管理应用的3D打印,防泄漏和柔性相变复合材料
Phase change composites (PCCs) have attracted much attention in the fields of thermal management due to their high latent heat. However, their risk of leakage and poor shape designability greatly limit their industrial applications. Therefore, there is an urgent need to develop leakage-proof and customizable PCCs to meet the emerging requirements of thermal management applications. Some scholars have proposed the concept of preparing PCCs by 3D printing technology, aiming to meet customized thermal management requirements of various electronic devices. Nevertheless, the phase change material leaking of PCCs under high temperature is still a tough problem to solve. In this study, expanded graphite (EG) is used as the carrier for paraffin wax (PW), which names as EP can tightly enveloping PW in its porous structure. Then, an innovative carbomer gel ink is prepared for 3D printing using EP and short carbon fiber (SCF) as thermal conductive fillers. Freeze-drying and polydimethylsiloxane (PDMS) infiltrating procedures are furtherly performed to ensure the flexibility of final PCCs samples. A maximum thermal conductivity of 2.89 W/(m·K) is obtained when the content of SCF/EP filler is 10 wt%. Importantly, the flexible PCCs prepared through this method effectively prevent the PW leaking during thermal management applications, thereby avoiding the consequent safety risks and enhancing the lifespan of electronic devices. This work opens up a promising pathway for the rapid fabrication of leakage-proof, customizable and flexible PCCs.
相变复合材料由于具有较高的潜热,在热管理领域受到了广泛的关注。然而,它们的泄漏风险和较差的形状可设计性极大地限制了它们的工业应用。因此,迫切需要开发防泄漏和可定制的PCCs,以满足热管理应用的新要求。一些学者提出了利用3D打印技术制备PCCs的概念,旨在满足各种电子器件的定制化热管理需求。然而,高温下PCCs相变材料的泄漏仍然是一个难以解决的问题。本研究以膨胀石墨(EG)作为石蜡(PW)的载体,将其称为EP,可以将PW紧密包裹在其多孔结构中。然后,利用EP和短碳纤维(SCF)作为导热填料,制备了一种用于3D打印的新型卡波姆凝胶油墨。冷冻干燥和聚二甲基硅氧烷(PDMS)渗透程序进一步执行,以确保最终PCCs样品的灵活性。当SCF/EP填料的含量为10 wt%时,其最大导热系数为2.89 W/(m·K)。重要的是,通过这种方法制备的柔性pcb有效地防止了热管理应用过程中PW的泄漏,从而避免了随之而来的安全风险,提高了电子设备的使用寿命。这项工作为快速制造防泄漏、可定制和灵活的PCCs开辟了一条有前途的途径。
Fatigue-creep damage model for carbon fibre reinforced composites under high temperature cyclic loading
Yi-Er Guo, De-Guang Shang, Lin-Xuan Zuo, Lin-Feng Qu, Chao-Lin Chen
doi:10.1016/j.compscitech.2024.110909
高温循环载荷下碳纤维增强复合材料疲劳蠕变损伤模型
In this paper, a fatigue-creep damage model that can take into account the interaction of fatigue and creep damage is proposed under high temperature cyclic loading. In the proposed model, the effect of temperature on creep damage, the variation of creep damage under different high temperature cyclic loading conditions, and fatigue-creep interaction damage are considered. In addition, in order to accurately describe the creep behavior of unidirectional laminates with different orientations, the damage mechanism of unidirectional laminates was also analyzed. The creep and fatigue test results at different temperatures showed that the proposed creep rupture time model and the fatigue-creep damage model considering the damage mechanisms can successfully predict the creep and fatigue lives of unidirectional laminates at high temperature, and the prediction results are in good agreement with the experimental data.
提出了一种考虑高温循环载荷下疲劳和蠕变损伤相互作用的疲劳-蠕变损伤模型。该模型考虑了温度对蠕变损伤的影响、不同高温循环加载条件下蠕变损伤的变化以及疲劳-蠕变相互作用损伤。此外,为了准确描述不同取向单向层合板的蠕变行为,还对单向层合板的损伤机理进行了分析。不同温度下的蠕变和疲劳试验结果表明,所建立的蠕变断裂时间模型和考虑损伤机理的疲劳-蠕变损伤模型能够较好地预测单向层合板的高温蠕变和疲劳寿命,预测结果与试验数据吻合较好。
Fraction-Dependent Filler Network in Silicone Rubber: Unraveling Abrupt Enhancement in Rheological Properties via Solvent Extraction and DLS Study
Qiuyu Long, Longjin Huang, Xueyan Zhao, Yuying Li, Yewei Xu, Yi Sun, Chunhua Zhu, Yu Liu
doi:10.1016/j.compscitech.2024.110895
硅橡胶中组分依赖的填料网络:通过溶剂萃取和DLS研究揭示了流变性能的突然增强
A pivotal nanofiller network will be constructed by the filler loading threshold inside the silicone rubber, leading to abrupt enhancement in the rheological properties of the composites. However, the contribution of the nanofiller network to the performance mutation is poorly understood due to lack of direct evidence to recognise the formation of filler networks. This work quantitatively investigated the filler aggregation network in solvent-extracted monodisperse silica-filled polydimethylsiloxane (PDMS) composites to interpret the rheological properties. The results indicated that, when filler loadings reach 60 phr, the size of the filler network reaches its maximum (1280.5 nm), significantly increasing the storage modulus (166 kPa) and Payne effect (163 kPa), due to the formation of a filler network confirmed by Dynamic Light Scattering (DLS) and scanning electron microscope (SEM) observation. The reduction in aggregate size observed with longer extraction times is because of the collapse of the nanofiller network, which occurs as the polymer chains are removed. The aggregates reappear in a monodisperse form as the extraction duration reaches 20 days. This confirms that filler aggregates of interconnected polymer chains can form a well-developed network structure that effectively supports and transfers stresses. This contributes to an in-depth understanding of the formation mechanism of nanofiller networks, aiding the advancement of high-performance polymer nanocomposites.
一个关键的纳米填充剂网络将由填充剂加载阈值在硅橡胶内部构建,导致复合材料的流变性能突然增强。然而,由于缺乏识别填充物网络形成的直接证据,纳米填充物网络对性能突变的贡献知之甚少。本文定量研究了溶剂萃取单分散二氧化硅填充聚二甲基硅氧烷(PDMS)复合材料的填料聚集网络,以解释其流变性能。结果表明,当填料负载达到60 phr时,填料网络的尺寸达到最大(1280.5 nm),显著增加了存储模量(166 kPa)和Payne效应(163 kPa),这是由于动态光散射(DLS)和扫描电镜(SEM)观察证实了填料网络的形成。随着萃取时间的延长,聚集体尺寸的减小是由于纳米填充剂网络的崩溃,这是由于聚合物链被去除而发生的。当提取时间达到20天时,聚集体以单分散形式重新出现。这证实了相互连接的聚合物链的填料聚集体可以形成一个发育良好的网络结构,有效地支持和传递应力。这有助于深入了解纳米填料网络的形成机制,有助于高性能聚合物纳米复合材料的发展。
Investigations on the Leak Resistance Performance and the Difference Mechanism of Composite Materials under Several Typical Curing Processes
Shu Liu, Lihua Zhan, Bolin Ma, Weitao Chen, Dechao Zhang, Shunming Yao, Chuan Du
doi:10.1016/j.compscitech.2024.110901
几种典型固化工艺下复合材料抗漏性能及差异机理研究
This study aims to investigate the leak resistance of carbon fiber composite products formed by various typical curing processes. Firstly, the leak rates of specimens produced through different curing methods were measured, and the defect were statistically analyzed. After that, the simulation approach was applied to numerically study the impact of these defect characteristics on leak rates was examined from the three factors of porosity, void distribution and void morphology, specimen with prefabricated defects was prepared, and its leak performance were tested to validate the simulation results. Finally, the differences in leak resistance among specimens under different curing processes were analyzed from the perspective of curing defects, and specific defect characteristics contributing to enhanced leak resistance were identified.
本研究旨在研究不同典型固化工艺形成的碳纤维复合材料制品的抗泄漏性能。首先,测量了不同养护方式下试件的泄漏率,并对缺陷进行了统计分析。在此基础上,采用模拟方法数值研究了这些缺陷特征对泄漏率的影响,从孔隙率、孔洞分布和孔洞形态三个方面考察了这些缺陷特征对泄漏率的影响,制备了预制缺陷试件,并对其泄漏性能进行了测试,验证了模拟结果。最后,从养护缺陷的角度分析了不同养护工艺下试件的抗漏性差异,确定了有助于增强抗漏性的具体缺陷特征。