今日更新:Composite Structures 1 篇,Composites Part A: Applied Science and Manufacturing 2 篇
Numerical investigation of internal damage in heterogeneous-structured laminates using a 3D multiple physical mechanisms based constitutive model
Shuai Zhu, Emmanuel Brousseau, Yiyu Shao, Wenfei Peng
doi:10.1016/j.compstruct.2024.118005
使用基于三维多物理机制的构成模型对异质结构层压板的内部损伤进行数值研究
Heterogeneous-structured laminates (HSLs), which consist of multiple layers of metallic materials arranged in successive pairs of coarse-grained (CG) and nano-grained (NG) layers, have been recently reported to display excellent balance of strength and ductility. However, it is argued that accompanying state-of-art numerical models developed to simulate the deformation of this specific class of composite materials have limitations for investigating their underlying damage evolution. Addressing this issue is essential to support the rational design, optimisation and application of HSLs, especially when subjected to contact and dynamic processes. For this reason, a novel 3D numerical framework for HSLs is proposed and tested in this research considering published experimental findings and dislocation theories. This framework comprehensively considers the evolution of various types of dislocations and back stress while being coupled with the Johnson Cook damage criterion. The HSL specimens simulated here were made of alternating layers of CG and NG copper separated by interface affected zones. Following initial microhardness and uniaxial tensile simulations on homogenous copper with different grain sizes, simulations of HSLs were conducted to study the effect of different layer thickness and the volume fraction of the NG layer. Overall, a good correlation between numerical and experimental results was achieved. An important and distinguishing characteristic of this research is that the proposed model enables the evolution of internal damage and the synergetic effect between the CG and NG layers to be investigated. Through the evaluation of the damage accumulation factor in the NG layer, the simulations results yielded quantitative information which aligned with the following known experimental observations: 1) the smaller the layer thickness, then the smaller the internal damage and 2) the internal damage increases with the increase in volume content of the NG layer. In addition, for a set simulated strain of 10%, the developed model could be used to show that the damage accumulation factor in the NG layer was 10 times lower than that in its counterpart, i.e., a stand-alone NG layer not sandwiched between two CG layers.
异质结构层压板(HSLs)由多层金属材料组成,粗粒(CG)层和纳米粒(NG)层依次排列,最近有报道称这种层压板在强度和延展性之间表现出极佳的平衡。然而,有观点认为,为模拟这类特定复合材料的变形而开发的最新数值模型在研究其潜在的损伤演变方面存在局限性。解决这一问题对于支持 HSL 的合理设计、优化和应用至关重要,尤其是在承受接触和动态过程时。为此,考虑到已发表的实验结果和位错理论,本研究提出并测试了新型 HSL 三维数值框架。该框架全面考虑了各类位错和背应力的演变,同时与约翰逊-库克损伤准则相结合。此处模拟的 HSL 试样由 CG 和 NG 铜交替层制成,并由界面影响区隔开。在对具有不同晶粒尺寸的均质铜进行初始显微硬度和单轴拉伸模拟后,对 HSL 进行了模拟,以研究不同层厚度和 NG 层体积分数的影响。总体而言,数值结果与实验结果之间实现了良好的相关性。这项研究的一个重要和显著特点是,所提出的模型能够研究内部损伤的演变以及 CG 层和 NG 层之间的协同效应。通过评估 NG 层的损伤累积因子,模拟结果得出了定量信息,这些信息与以下已知的实验观察结果一致:1)层厚度越小,内部损伤越小;2)内部损伤随 NG 层体积含量的增加而增加。此外,在设定模拟应变为 10%的情况下,所建立的模型可用于证明 NG 层的损伤累积系数比其对应层(即未夹在两个 CG 层之间的独立 NG 层)的损伤累积系数低 10 倍。
MXene bridging graphite nanoplatelets for electrically and thermally conductive nanofiber composites with high breathability
Yuntao Liu, Qin Su, Wei Xiao, Lv Li, Jing Wen, Yuqing Wang, Haidi Wu, Ling Wang, Guoqiang Zhang, Huaiguo Xue, Jiefeng Gao
doi:10.1016/j.compositesa.2024.108134
用于具有高透气性的导电导热纳米纤维复合材料的 MXene 桥接石墨纳米片
Electrically and thermally conductive polymer composites (CPCs) have promising applications in flexible and wearable electronics, and it remains difficult for the trade-off between the electrical and thermal properties and the breathability. We propose a “MXene bridging graphite nanoplatelets (GNPs)” strategy to prepare conductive membranes with high conductivity and excellent breathability. Rigid GNPs are randomly distributed inside polyurethane nanofibers and expand the network. MXene nanosheets are decorated onto the nanofibers and bridge GNPs to reduce the thermal and electrical contact resistance. The synergy of MXene and GNPs improves electrical and thermal conductivity without sacrificing their breathability. The electrical and thermal conductivity of the composites can reach 64.4 S/m and 4.9 W (m K)−1, respectively. In addition, the nanofiber composites with strong interfacial interactions and thus superior durability show outstanding photothermal conversion and heat dissipation capability. This study can provide inspiration for designing multi-functional, breathable CPCs with potential applications in wearable electronics.
导电和导热聚合物复合材料(CPCs)在柔性和可穿戴电子设备中有着广阔的应用前景,但如何在导电、导热性能和透气性能之间取得平衡仍是一个难题。我们提出了一种 "MXene 桥接石墨纳米颗粒(GNPs)"策略,以制备具有高导电性和良好透气性的导电膜。刚性 GNPs 在聚氨酯纳米纤维中随机分布,并扩展网络。将 MXene 纳米片装饰到纳米纤维上,并在 GNPs 上架桥,以降低热阻和电接触电阻。MXene 和 GNPs 的协同作用提高了导电性和导热性,同时又不影响其透气性。复合材料的导电率和导热率分别达到 64.4 S/m 和 4.9 W (m K)-1。此外,纳米纤维复合材料具有很强的界面相互作用,因此具有极佳的耐久性,同时还具有出色的光热转换和散热能力。这项研究为设计多功能透气 CPC 提供了灵感,有望应用于可穿戴电子产品。
Ionothermal synthesis of fiber-reinforced carbon aerogel composites from fructose with high mechanical and thermal insulation properties
Jianchao Hao, Yuan Cheng, Mingyi Tan, Yandong Han, Wenbo Han, Daming Chen, Xinghong Zhang, Guiqing Chen
doi:10.1016/j.compositesa.2024.108135
利用果糖离子热合成具有高机械和隔热性能的纤维增强碳气凝胶复合材料
In this work, carbon fiber reinforced biomass carbon aerogel composites (CF/CA) were prepared by ionothermal synthesis using fructose as the raw material and oxidized polyacrylonitrile fiber as the reinforcing agent. During the preparation process, we have mixed fructose with oxidized polyacrylonitrile fibers and subjected them to a carbonization process under the conditions of hot ionic liquids. By controlling the reaction conditions, we successfully prepared fiber-reinforced carbon aerogel composites with excellent properties. The CF/CA has a high compressive strength (3.306 MPa). At the same time, the original low thermal conductivity (0.106 W·m−1·K−1) and low density (0.2976 g/cm2) of the carbon aerogel are maintained. In this work, the mechanical properties of carbon aerogel are improved to 230 % without changing the thermal insulation properties of CA, which makes a certain progress compared with the similar research. These excellent properties make CF/CA a promising engineering material. Moreover, we found that about 95 % of the ionic liquid can be recovered by evaporating under reduced pressure, and the recovered ionic liquid is still usable. This discovery provides a possibility for the green and sustainable development of the preparation process of carbon aerogels. This study provides new ideas and methods to further optimize the properties and applications of biomass carbon aerogels and their composites.
本研究以果糖为原料,氧化聚丙烯腈纤维为增强剂,通过离子热合成法制备了碳纤维增强生物质碳气凝胶复合材料(CF/CA)。在制备过程中,我们将果糖与氧化聚丙烯腈纤维混合,并在热离子液体条件下对其进行碳化处理。通过控制反应条件,我们成功制备出了性能优异的纤维增强碳气凝胶复合材料。CF/CA 具有很高的抗压强度(3.306 兆帕)。同时,还保持了碳气凝胶原有的低导热系数(0.106 W-m-1-K-1)和低密度(0.2976 g/cm2)。在这项研究中,碳气凝胶的机械性能提高了 230%,而 CA 的隔热性能却没有改变,这与同类研究相比取得了一定的进步。这些优异的性能使 CF/CA 成为一种前景广阔的工程材料。此外,我们还发现,通过减压蒸发可回收约 95% 的离子液体,且回收的离子液体仍可使用。这一发现为碳气凝胶制备工艺的绿色可持续发展提供了可能。这项研究为进一步优化生物质碳气凝胶及其复合材料的性能和应用提供了新的思路和方法。