今日更新:Composite Structures 1 篇,Composites Part A: Applied Science and Manufacturing 4 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 1 篇
A kinking-based failure model for engineering simulation of compressive crushing of composite structures
Niklas Jansson, Martin Fagerström
doi:10.1016/j.compstruct.2023.117755
基于扭结的失效模型,用于复合材料结构压缩挤压的工程模拟
The use of continuum damage models is state of the art for the finite element modelling of progressive damage and failure under compressive loading in composites during e.g. crash and impact simulations. However, after failure initiation the compressive stress is quickly degraded to zero alternatively to a plateau with constant stress and at a certain point the element needs to be deleted due to the damage level or large element deformation. This effectively represent a void in the material which contrasts with reality where a fully formed kink band would be expected to have compressive properties similar to the transverse direction of the ply. To better represent this physical behaviour is here a kinking formulation developed that instead of the common constant stress plateau after initial softening features a stiffening at larger strains. This formulation has been implemented in a commercial FE-code complemented by criteria for kinking initiation and kink band broadening. The results presented show the novelty of the model in that it describes a chain of events starting with initiation of kinking, progressing to the growth of kink bands through the element and finally including an increase in stress that initiate kinking in adjacent elements.
在碰撞和冲击模拟等过程中,使用连续损伤模型对复合材料在压缩载荷作用下的渐进损伤和失效进行有限元建模是目前最先进的方法。然而,在失效开始后,压缩应力会迅速衰减为零,或者变为具有恒定应力的高原,在某一点上,由于损伤程度或较大的元素变形,需要删除元素。这实际上代表了材料中的空隙,与实际情况形成鲜明对比,完全形成的扭结带预计会具有与层板横向相似的抗压性能。为了更好地表现这种物理行为,我们在此开发了一种扭结配方,这种配方在初始软化后不再是常见的恒定应力高原,而是在较大应变时出现僵化。该公式已在商用 FE 代码中实施,并辅以扭结起始和扭结带扩展的标准。研究结果表明了该模型的新颖性,它描述了一连串的事件,从开始的扭结,到扭结带在元件中的扩展,最后包括应力的增加,从而引发相邻元件的扭结。
A strategy to fabricate hierarchical microporous architecture of polyimide nanofibrous aerogels with efficient electromagnetic wave absorption and thermal insulation
Meng Sun, Zhengyu Guo, Wenting Zhang, Enjie Ding, Xiang Li, Ming Yin, Chuyang Luo, Liying Zhang
doi:10.1016/j.compositesa.2023.107940
制造具有高效电磁波吸收和隔热性能的分层微孔结构聚酰亚胺纳米纤维气凝胶的策略
The aviation industry requires advanced aerogels that combine both electromagnetic wave (EM) attenuation and thermal insulation capabilities. This work involved the fabrication of Ti3C2Tx MXene/polyimide nanofibrous (PINF) aerogels through freeze-drying and thermal imidization. The hierarchical microporous architecture was formed by the interconnected primary pores induced by the removal of ice crystals and secondary pores from the PINF web. The unique highly porous 3D network of the nanofibrous aerogel provided well-matched impedance and enhanced multiple reflections and scattering of EM waves. The polar functional groups and defects on MXene induced dipole polarization, and the heterointerfaces between the PINFs and MXene enhanced the interfacial polarization. Consequently, the MXene/PINF aerogels exhibited efficient microwave absorption, showing a minimum reflection loss (RLmin) of -37.9 dB and an effective absorption bandwidth (EAB) of 3.3 GHz. Moreover, nanofibrous aerogels also exhibited low thermal conductivity and remarkable compression properties, making them suitable for utilization in complex environments.
航空业需要兼具电磁波(EM)衰减和隔热能力的先进气凝胶。这项工作涉及通过冷冻干燥和热亚胺化制造 Ti3C2Tx MXene/聚酰亚胺纳米纤维(PINF)气凝胶。分层微孔结构是由冰晶去除后产生的相互连接的一级孔隙和 PINF 网中的二级孔隙形成的。纳米纤维状气凝胶独特的高多孔三维网络提供了良好的阻抗匹配,并增强了电磁波的多次反射和散射。MXene 上的极性官能团和缺陷诱导了偶极极化,而 PINF 与 MXene 之间的异质界面增强了界面极化。因此,MXene/PINF 气凝胶具有高效的微波吸收能力,其最小反射损耗(RLmin)为 -37.9 dB,有效吸收带宽(EAB)为 3.3 GHz。此外,纳米纤维气凝胶还表现出较低的热导率和显著的压缩特性,使其适合在复杂环境中使用。
Tensile and flexural mechanical attributes of hybrid carbon/basalt fiber metal laminates under various hybridization and stacking sequences
Yu Wang, Weifu Sun, Lei Cao
doi:10.1016/j.compositesa.2023.107942
不同杂化和堆叠顺序下碳/钴纤维混合金属层压板的拉伸和弯曲机械属性
In this work, experimental measurements and theoretical validation are adopted to examine the tensile and flexural behaviors of titanium-based carbon/basalt fiber metal laminates under various hybridization ratios and stacking sequences. Firstly, the mechanical response and damage patterns of fiber metal laminates (FMLs) subjected to different tensile and flexural loads have been explored. By observing the fracture surfaces of FMLs with various hybridization ratios and stacking sequences, scanning electron microscopy (SEM) has been used to identify the related microscopic damage patterns. The principal damage mechanism were attributed to fiber/matrix debonding, matrix microcrack, fiber pull-out, and delamination. Subsequently, to analyze the discreteness of experimental results and evaluate the theoretical flexural strength of FMLs under different conditions, the two-parameter Weibull statistics model for engineering application of FMLs was established. These results indicate that the tensile and flexural strength of FMLs can be improved by altering the hybridization ratios and stacking sequences. The thorough understanding of the mechanical behavior and failure mechanism of FMLs under various hybridization conditions can provide the basis for the design and utilization of FMLs structures.
本研究通过实验测量和理论验证,研究了钛基碳/钴纤维金属层压板在不同杂化比和堆叠顺序下的拉伸和弯曲行为。首先,研究了金属纤维层压板(FML)在不同拉伸和弯曲载荷下的力学响应和损伤模式。通过观察不同杂化比和堆叠顺序的金属纤维层压板的断裂面,利用扫描电子显微镜(SEM)确定了相关的微观损伤模式。主要的损伤机制可归结为纤维/基体脱粘、基体微裂纹、纤维拉出和分层。随后,为了分析实验结果的离散性并评估不同条件下 FML 的理论抗弯强度,建立了 FML 工程应用的双参数 Weibull 统计模型。这些结果表明,可以通过改变杂化比和堆叠顺序来提高 FML 的拉伸强度和抗弯强度。透彻了解 FML 在各种杂化条件下的力学行为和失效机理,可为 FML 结构的设计和利用提供依据。
Harnessing the Power of Carbon Fiber Reinforced Liquid Crystal Elastomer Composites for High-Performance Aerospace Materials: A Comprehensive Investigation on Reversible Transformation and Shape Memory Deformation
Yuliang Xia, Tong Mu, Yanju Liu, Jinsong Leng
doi:10.1016/j.compositesa.2023.107943
利用碳纤维增强液晶弹性体复合材料的力量制造高性能航空航天材料:对可逆变形和形状记忆变形的全面研究
Liquid Crystal Elastomers (LCEs) showcase transformative features making them suitable for rigorous applications, notably aerospace. However, their standalone mechanical properties often fall short. This study introduces the incorporation of carbon fiber to form a reinforced LCE composite, LCEC, aimed at enhancing mechanical performance while maintaining reversible deformation and shape memory attributes. Molecular-level analysis indicates an upsurge in overall composite performance with improved storage modulus (1.1 GPa at 25 °C), heightened reversible deformation, and better shape memory functionality. Both materials retain transformation properties under gamma-ray irradiation. This investigation into LCE and LCEC performance underscores their potential in demanding environments due to improved mechanical strength, transformability, shape memory performance, and radiation resistance. The research offers insights into micro-level alterations leading to macro-level enhancements in material properties, paving the way for future advancements in fields like robotics and aerospace.
液晶弹性体(LCE)具有变革性的特点,适合于严格的应用领域,尤其是航空航天领域。然而,它们的独立机械性能往往不尽如人意。本研究介绍了加入碳纤维形成增强型液晶弹性体复合材料 LCEC 的方法,旨在提高机械性能,同时保持可逆变形和形状记忆特性。分子层面的分析表明,这种复合材料的整体性能得到了提升,存储模量提高(25 °C时为1.1 GPa),可逆形变增加,形状记忆功能增强。在伽马射线辐照下,两种材料都能保持转化特性。对 LCE 和 LCEC 性能的研究强调了它们在苛刻环境中的潜力,因为它们具有更好的机械强度、可变形性、形状记忆性能和抗辐射性。这项研究深入揭示了微观层面的改变导致材料性能宏观层面的增强,为机器人和航空航天等领域的未来进步铺平了道路。
A low-cost and liquid oxygen-compatible epoxy matrix of composites by introducing aryl phosphinate diglycidyl ether
Juanzi Li, Jia Yan, Duo Chen, Yunguang Cui, Jianing Wei, Zhenyu Wang, Hao Huang, Zhanjun Wu
doi:10.1016/j.compositesa.2023.107944
引入芳基膦酸二缩水甘油醚的低成本液氧兼容环氧基复合材料
Replacing traditional metal tanks with composite liquid oxygen (LOX) tanks would make significant contribution to the weight reduction of rockets. However, the epoxy resins (EP) matrix of composites is incompatible with LOX, which limits the application of composite LOX tanks. In this study, an aryl phosphinate diglycidyl ether (PDGEP) was synthesized using 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (ODOPB) and epichlorohydrin via a single step. The structure of PDGEP was confirmed by FTIR spectra, NMR and LC-MS analysis. Meanwhile, PDGEP was introduced into biphenol A (E51) resin at different weight ratios by physical blending. When the content of PDGEP exceeded 10 phr, E51 matrix exhibited compatibility with LOX. The LOX-compatible mechanism was investigated by TGA, UL-94, TG-FTIR-MS analysis and XPS analysis. The results showed that the enhanced thermal stability under high temperatures, the quenching effects from the phosphorus-containing free radicals, the decrease of the combustible volatiles, and the shielding and protective char layer with highly carbonized aromatic networks were all responsible for the compatibility of E51 matrix with LOX. Furthermore, the flexural strength (883.31 MPa) and flexural modulus (14.83 GPa) of the carbon fiber reinforced EP10 (CF/EP10) composites at 90 K increased by 2.3% and 12.9% than those of the CF/EP0 composites. The LOX-compatible resin matrix and composites exhibit good potential for developing light-weight LOX composite cryotanks.
用复合材料液氧(LOX)贮箱取代传统的金属贮箱将大大减轻火箭的重量。然而,复合材料的环氧树脂(EP)基体与液氧不相容,这限制了复合材料液氧罐的应用。本研究利用 10-(2,5-二羟基苯基)-9,10-二氢-9-氧杂-10-磷菲-10-氧化物(ODOPB)和环氧氯丙烷一步合成了芳基膦酸二缩水甘油醚(PDGEP)。傅立叶变换红外光谱、核磁共振和液相色谱-质谱分析证实了 PDGEP 的结构。同时,通过物理混合将不同重量比的 PDGEP 加入双酚 A(E51)树脂中。当 PDGEP 的含量超过 10 phr 时,E51 树脂基体表现出与 LOX 的相容性。通过 TGA、UL-94、TG-FTIR-MS 分析和 XPS 分析研究了与 LOX 相容的机理。结果表明,高温下热稳定性的增强、含磷自由基的淬火效应、可燃挥发物的减少以及高度碳化芳香族网络的屏蔽和保护炭层都是 E51 基体与 LOX 相容性的原因。此外,碳纤维增强 EP10(CF/EP10)复合材料在 90 K 时的抗弯强度(883.31 MPa)和抗弯模量(14.83 GPa)比 CF/EP0 复合材料分别提高了 2.3% 和 12.9%。LOX兼容树脂基体和复合材料在开发轻质LOX复合低温槽方面具有良好的潜力。
Effects of rCF attributes and FDM-3D printing parameters on the mechanical properties of rCFRP
Huanbo Cheng, Mingxi Tang, Huafeng Wang, Jinhu Zhou, Qingze Wang, He Zhai, Zhengchun Qian
doi:10.1016/j.compositesb.2023.111122
rCF 属性和 FDM-3D 印刷参数对 rCFRP 力学性能的影响
In order to realize high-quality and environment-friendly recycling of carbon fiber reinforced composite (CFRP) waste and high-value reuse of recycled carbon fiber (rCF), this paper proposes an additive remanufacturing process of recycled carbon fiber reinforced composite (rCFRP). The material attribute of rCF recycled by the thermally activated oxide semiconductor was analyzed and the effect of fused deposition modeling-3D (FDM-3D) printing parameters on mechanical properties of rCFRP was investigated, and FDM-3D printed rCFRP products for automotive were prepared. The results illustrate that rCF possesses the same excellent material attribute as the virgin carbon fiber, and optimizing FDM-3D printing parameters can effectively improve the mechanical properties of rCFRP. FDM-3D printed rCFRP products are of promising application in the field of automotive lightweighting due to its characteristics of personalized customization and low cost, which verifies the feasibility of the additive remanufacturing process mentioned above.
为了实现碳纤维增强复合材料(CFRP)废弃物的高质量环保回收和再生碳纤维(rCF)的高价值再利用,本文提出了一种再生碳纤维增强复合材料(rCFRP)的添加剂再制造工艺。分析了热激活氧化物半导体回收的 rCF 的材料属性,研究了熔融沉积建模-3D(FDM-3D)打印参数对 rCFRP 力学性能的影响,并制备了用于汽车的 FDM-3D 打印 rCFRP 产品。结果表明,rCF 具有与原始碳纤维相同的优异材料属性,优化 FDM-3D 印刷参数可有效改善 rCFRP 的力学性能。FDM-3D 打印 rCFRP 产品具有个性化定制和低成本的特点,在汽车轻量化领域具有广阔的应用前景,验证了上述添加剂再制造工艺的可行性。
Enhanced thermal conductivity and electrical insulation by patterned self-assembly of electrospun nanofibers
Wei-Hua Han, Li-Rui Shi, Yu Long, Xin Zhou, Yuan-Yi Kang, Qing-Yu Wang, Chun-Cheng Hao
doi:10.1016/j.compscitech.2023.110367
通过电纺纳米纤维的图案化自组装增强导热性和电绝缘性
Low intrinsic thermal conductivity (TC) of polymer materials has severely limited their further applicability in electronic and electrical products. To enhance the TC, a strategy for constructing nanofiller-based thermal conductive networks by patterned self-assembly of electrospun nanofibers was first proposed in this paper. By selecting a regular metal mesh as the collector, the electrostatic field-induced directional deposition of nanofibers was achieved, thereby constructing interconnected heat transfer paths aligned in at least four directions. The in-plane TC of heat-pressed electrospun polyvinylidene fluoride (PVDF) nanofibers with 20 wt% loading of boron nitride nanosheets (BNNSs) can reach 7.27 W/(m·K). Electrical insulation of the PVDF/BNNS composites has also been confirmed, showing high volume resistivity and breakdown strength, which have increased by 460.0 % and 26.6 %, respectively, compared to pure PVDF. Finally, a double-layer composite film with waterproof and easy-cleaning characteristics was prepared for electronic device packaging. This simple and efficient preparation strategy for thermal conductive networks may bring new perspectives to thermal management applications.
聚合物材料的固有热导率(TC)较低,严重限制了其在电子和电气产品中的进一步应用。为了提高导热系数,本文首次提出了一种通过电纺纳米纤维的图案化自组装来构建基于纳米填料的导热网络的策略。通过选择规则的金属网作为收集器,实现了静电场诱导的纳米纤维定向沉积,从而构建了至少四个方向上相互连接的传热路径。含有 20 wt% 氮化硼纳米片 (BNNS) 的热压电纺聚偏二氟乙烯 (PVDF) 纳米纤维的面内 TC 值可达到 7.27 W/(m-K)。PVDF/BNNS 复合材料的电绝缘性能也得到了证实,显示出较高的体积电阻率和击穿强度,与纯 PVDF 相比,体积电阻率和击穿强度分别提高了 460.0% 和 26.6%。最后,制备出了一种具有防水和易清洁特性的双层复合薄膜,可用于电子设备包装。这种简单高效的导热网络制备策略可能会为热管理应用带来新的前景。