今日更新:Composite Structures 2 篇,Composites Part A: Applied Science and Manufacturing 1 篇
Assessment of ply thickness and aluminum foils interleaving on the impact response of CFRP composites designed for cryogenic pressure vessels
Claudia Sergi, Nicola Ierardo, Fabrizio Sarasini, Luca Lampani, Paolo Gaudenzi, Teodoro Valente, Jacopo Tirillò
doi:10.1016/j.compstruct.2024.118563
低温压力容器用CFRP复合材料厚度与铝箔交错对冲击响应的评价
Carbon fiber reinforced polymer (CFRP) proved to be the best choice to produce cryogenic pressure vessels coupling a reduced weight with superior mechanical performance. Despite this, CFRPs are prone to fuel leakage due to interconnected matrix cracks resulting from mechanical and thermal stresses. Two strategies were coupled in this work to reduce fuel permeability, i.e., increase of plies number and metallic film interleaving, evaluating the cryogenic impact response of these new configurations. At first, the only ply thickness effect was assessed and the hybrid sandwich-like (SL) configuration with traditional CFRP (RC) skins and a thin-ply (TP) core displayed impact and residual flexural properties close to RC ones. Then, the effect of aluminum foils interleaving was investigated, and the interleaved SL configuration displayed higher residual flexural properties than interleaved RC for all temperatures, e.g., residual flexural strength 30.3 % and 14.6 % higher at room temperature and −70 °C, respectively.
碳纤维增强聚合物(CFRP)被证明是制造低温压力容器的最佳选择,它具有减轻重量和优异的机械性能。尽管如此,由于机械和热应力导致的相互连接的基体裂纹,cfrp容易发生燃油泄漏。本文将增加层数和金属膜交错两种策略结合起来降低燃料渗透率,并对这两种新配置的低温冲击响应进行了评价。首先,仅评估了厚度效应,传统CFRP (RC)外皮与薄层(TP)芯的混合三明治状(SL)结构显示出与RC相近的冲击和残余弯曲性能。在室温和- 70 °C下,交错的SL结构比交错的RC结构具有更高的残余抗弯性能,其残余抗弯强度分别高出30.3 %和14.6 %。
Temperature-dependent R-curve and traction-separation relation in mode-I fracture of GFRP laminates
Yu Gong, Zeyu Shan, Meijuan Shan, Fengrui Liu, Jianyu Zhang, Libin Zhao, Ning Hu
doi:10.1016/j.compstruct.2024.118573
GFRP层合板i型断裂中随温度变化的r曲线及拉伸-分离关系
The R-curve and fiber bridging phenomenon in mode-I fracture of glass-fiber reinforced laminates at different temperatures are investigated in this study, aiming to reveal their changes with temperature. The mode-I fracture experiments are carried out by adopting double cantilever beam (DCB) configuration at −55 ℃, 23 ℃ and 80 ℃. Fiber bridging is observed during the tests. The R-curve and bridging traction are quantitatively analyzed, from which the relationship between the R-curve and fiber bridging phenomenon, and temperature is obtained. It is found that fiber bridging effect is enhanced with the increase of temperature. The bridging traction of specimens tested at 80 ℃ is significantly higher than that at −55 ℃ and 23 ℃. An R-curve model considering both temperature and fiber bridging effects is proposed. In addition, bilinear and tri-linear traction-separation relations (TSLs) are utilized to establish a numerical model for the simulation of delamination growth behavior with the consideration of the temperature-dependent effect on the mechanical properties of composite materials. When using the bilinear TSL, the fiber bridging is considered by integrating the resulted R-curve into finite element model via a user-defined USDFLD subroutine. Effects of initial interface stiffness, interface strength and viscosity coefficient on simulated results are numerically investigated. Finally, applicability of the established numerical models is illustrated by comparisons between the simulations and the test results.
本文研究了不同温度下玻璃纤维增强层压板i型断裂的r曲线和纤维桥接现象,揭示了它们随温度的变化规律。采用双悬臂梁(DCB)结构,在- 55℃、23℃和80℃条件下进行i型断裂实验。在测试过程中观察到光纤桥接。定量分析了r曲线和桥接牵引力,得到了r曲线与纤维桥接现象、温度之间的关系。结果表明,随着温度的升高,纤维桥接效应增强。80℃下试件的桥接牵引力显著高于−55℃和23℃。提出了同时考虑温度和光纤桥接效应的r曲线模型。此外,利用双线性和三线性牵引分离关系(TSLs)建立了考虑温度对复合材料力学性能影响的分层生长行为模拟数值模型。当使用双线性TSL时,通过用户定义的USDFLD子程序将结果r曲线集成到有限元模型中来考虑光纤桥接。数值研究了初始界面刚度、界面强度和黏度系数对模拟结果的影响。最后,通过与试验结果的比较,说明了所建立数值模型的适用性。
Microstructural behavior of CNT-PDMS thin-films for multifunctional systems
Matthew Phillips, Pouria Zaghari, Jong Eun Ryu, Mohammed Zikry
doi:10.1016/j.compositesa.2024.108473
多功能系统CNT-PDMS薄膜的微观结构行为
Heterogeneous ribbed and non-ribbed carbon nanotube (CNT)-PDMS thin-film systems manufactured by large-scale rolling exhibit large-strain and high strain-rate characteristics with favorable surface behaviors, such as superhydrophobicity and drag reduction. However, it is not well understood how the multi-phase microstructure and material properties of non-ribbed thin-films are related to the surface material behavior and fracture. Hence, the objective of this investigation is to characterize the large-strain mechanical behavior and the microstructure of various CNT-PDMS compositions to understand how the CNT loading, agglomeration, distribution, and orientation affect the mechanical behavior and fracture of CNT-PDMS unribbed systems. Non-ribbed thin tensile testing specimens were fabricated for neat PDMS and CNT-PDMS with different weight CNT distributions to understand non-ribbed behavior. The ultimate strain, strength, and global stress–strain behavior were obtained by uniaxial mechanical testing. Scanning electron microscopy (SEM) of the fracture surface was also obtained for each sample to analyze the microstructure and relate the damage mode to the different weight distributions. Based on these experimental measurements and observations, large-strain, hyperelastic and hyper-viscoelastic material models were used to characterize the material behavior. The hyper-viscoelastic material model was shown to provide the most accurate material description of the thin-film behavior of the viscoelastic PDMS with high-strength CNTs
通过大规模轧制制备的非均相罗纹和非罗纹碳纳米管(CNT)-PDMS薄膜系统具有大应变和高应变率的特性,并具有良好的表面性能,如超疏水性和减阻性。然而,非带肋薄膜的多相组织和材料性能与表面材料行为和断裂之间的关系尚不清楚。因此,本研究的目的是表征不同碳纳米管- pdms成分的大应变力学行为和微观结构,以了解碳纳米管的载荷、团聚、分布和取向如何影响碳纳米管- pdms无肋体系的力学行为和断裂。采用不同重量碳纳米管分布的纯PDMS和CNT-PDMS制备了无肋薄拉伸试样,了解其无肋性能。通过单轴力学试验获得了极限应变、强度和整体应力-应变行为。对各试样进行了断口表面扫描电镜(SEM)分析,并将损伤模式与不同重量分布联系起来。基于这些实验测量和观察,采用大应变、超弹性和超粘弹性材料模型来表征材料的行为。结果表明,超粘弹性材料模型能够最准确地描述含高强度碳纳米管的粘弹性PDMS的薄膜行为