Concurrent optimization method of principal stress orientation interpolated continuous fiber angle (PSO-CFAO) and structural topology
Ye Hongling, Dong Yongjia, Yang Jiaxi, Wang Weiwei, Cheng Ming
doi:10.1016/j.compstruct.2023.117572
主应力取向插值连续纤维角 (PSO-CFAO) 与结构拓扑的并行优化方法
Continuous fiber-reinforced polymers (CFRPs) have been widely applied in aerospace and other fields due to their excellent mechanical properties, which highly depends on the material distribution and fiber orientations. The designability of CFRP structures and fiber distributions provides an opportunity for achieving better physical properties through optimization. However, local optima and the dependence of initial fiber angle variables make the concurrent optimization of fiber orientation and topology a challenging problem. In this paper, the principal stress orientation interpolated continuous fiber angle optimization (PSO-CFAO) method combined with the independent continuous mapping (ICM) method is proposed to realize the design of CFRP structures with a clear macroscopic topology and microscopic fiber distribution. A sigmoid function is applied to interpolate the fiber angle variables by the principal stress orientation. The fiber angle variables are modified and a continuous fiber design is obtained during the iteration process, which reduces the possibility of a local optimum. Several examples are provided to prove the effectiveness and stability of the proposed method, and the expected results are acquired for different initial fiber angles, material parameters and mesh densities. The proposed method provides guidance for the design of CFRP structures and the planning of fiber laying paths.
连续纤维增强聚合物(CFRP)因其优异的机械性能而被广泛应用于航空航天和其他领域,而机械性能在很大程度上取决于材料分布和纤维取向。CFRP 结构和纤维分布的可设计性为通过优化获得更好的物理特性提供了机会。然而,局部最优化和初始纤维角度变量的依赖性使得同时优化纤维取向和拓扑结构成为一个具有挑战性的问题。本文提出了结合独立连续映射(ICM)方法的主应力取向插值连续纤维角度优化(PSO-CFAO)方法,以实现具有清晰宏观拓扑和微观纤维分布的 CFRP 结构设计。通过主应力取向应用 sigmoid 函数对纤维角度变量进行插值。在迭代过程中修改纤维角度变量并获得连续纤维设计,从而减少局部最优的可能性。我们提供了几个实例来证明所提方法的有效性和稳定性,并在不同的初始纤维角度、材料参数和网格密度下获得了预期结果。所提出的方法为 CFRP 结构的设计和纤维铺设路径的规划提供了指导。
A novel Multisource Energy Harvester with Enhanced Thermal Conductivity for Efficient Energy Harvesting and Superior EMI Shielding
Yang Yabi, Liu Shuang, Jin Liang, Li Guo, Quan Bingqing, Chen Qiufei, Tang Xiangying, Ji Xiaofan, Wu Hao, Lu Xiang, Qu Jinping
doi:10.1016/j.compositesa.2023.107803
一种新型多源能量收集器,具有增强的热传导性,可实现高效能量收集和出色的电磁干扰屏蔽
With the rapid growth of industries, renewable energy sources like wind and solar have emerged as prominent alternatives. However, their inherent intermittency demands the development of efficient energy harvester technologies. Conventional energy harvesters are limited to capturing a single energy type, resulting in compromised storage capabilities. Moreover, the detrimental effects of electromagnetic interference (EMI) on equipment necessitate immediate attention. To address these challenges, we present the development of a novel phase change composite, CMW@PEG, which possesses remarkable enhancements in thermal conductivity (1.26 W/m∙K), electrical conductivity (71.9 S/cm), and UV absorption capacity (close to 1). Notably, this composite exhibits an outstanding EMI shielding capability of 49.36 dB, safeguarding equipment operations effectively. Furthermore, it showcases impressive solar-thermal (87.9%) and electric-thermal (93.3%) conversion efficiencies. The unique properties of CMW@PEG offer a pioneering strategy for harnessing and utilizing renewable energy efficiently and hold tremendous promise in advancing the sustainable energy landscape.
随着工业的快速发展,风能和太阳能等可再生能源已成为重要的替代能源。然而,它们固有的间歇性要求开发高效的能量收集器技术。传统的能量收集器仅限于捕捉单一类型的能量,导致存储能力大打折扣。此外,电磁干扰(EMI)对设备的有害影响也需要立即引起重视。为了应对这些挑战,我们开发了一种新型相变复合材料 CMW@PEG,它在导热性(1.26 W/m∙K)、导电性(71.9 S/cm)和紫外线吸收能力(接近 1)方面都有显著提高。值得注意的是,这种复合材料的电磁干扰屏蔽能力高达 49.36 dB,可有效保护设备运行。此外,它还具有出色的太阳-热转换效率(87.9%)和电-热转换效率(93.3%)。CMW@PEG 的独特性能为高效利用可再生能源提供了一种开创性的策略,在推动可持续能源领域的发展方面前景广阔。
The oxide-layer configuration alteration and pseudo-ductile crack propagation mechanisms in composites induced by different relative thicknesses of CVI HfC-SiC multiphase matrix
Shi Xinhao, Feng Tao, Hou Wanbo, Ding Jiahui, Liu Xianglei, Lin Hongjiao, Tong Mingde
doi:10.1016/j.compositesb.2023.111012
不同相对厚度的 CVI HfC-SiC 多相基体诱导复合材料中氧化层构型的改变和伪电导裂纹扩展机制
Carbon fiber-reinforced HfC-SiC ceramic matrix composites (Cf/HfC-SiC) with different HfC-SiC matrix thicknesses were prepared by the chemical vapor infiltration method. The microstructure, ablation, and pseudo-ductile fracture behaviors of the composites were studied. The results proved that with the change of the HfC-SiC layer relative thickness, the oxide-layer configuration changed to promote its densification, which improved the ablative protection and mechanical properties of Cf/HfC-SiC composites. After ablation, when the relative volume proportion of the HfC-SiC matrix was the utmost (24.7/15.5), the composites had the best ablation resistance due to the tubular lamination configuration HfO2 layer. This caused the composite to have the highest residual bending strength (215.8MPa) and strength retention rate (79.7%). In addition, a pseudo-ductile crack propagation model was established to determine the influence of the induction of residual stress and the relative HfC-SiC layer thickness on the fracture behavior in the composites. Results suggested that in the real crack deflection mechanism, due to the induction of residual stress, the stress state in the HfC-SiC matrix with the increase of the HfC layer thickness changed to form more ring deflection cracks at the HfC/SiC interface. It provides a way to study the pseudo-ductility behavior of multiphase matrix composites and explain the improvement of its predictability and failure.
采用化学气相渗透法制备了不同 HfC-SiC 基体厚度的碳纤维增强 HfC-SiC 陶瓷基复合材料(Cf/HfC-SiC)。研究了复合材料的微观结构、烧蚀和假韧性断裂行为。结果证明,随着 HfC-SiC 层相对厚度的变化,氧化物层的构型也发生了变化,从而促进了其致密化,提高了 Cf/HfC-SiC 复合材料的烧蚀保护性能和力学性能。烧蚀后,当 HfC-SiC 基体的相对体积比例最大(24.7/15.5)时,由于 HfO2 层呈管状层叠构造,复合材料的抗烧蚀性能最好。这使得复合材料具有最高的残余弯曲强度(215.8MPa)和强度保持率(79.7%)。此外,还建立了一个假导裂纹扩展模型,以确定残余应力的诱导和 HfC-SiC 层的相对厚度对复合材料断裂行为的影响。结果表明,在真实的裂纹偏转机制中,由于残余应力的诱导,HfC-SiC 基体中的应力状态随着 HfC 层厚度的增加而改变,在 HfC/SiC 界面形成更多的环形偏转裂纹。这为研究多相基复合材料的假韧性行为提供了一种方法,并解释了如何提高其可预测性和失效性。
Herbaceous lignin valorization through integrated copper-catalyzed hydrogenolysis and chemical functionalization
Yin Wen-Zheng, Xiao Ling-Ping, Wang Qiang, Lv Yi-Hui, Zou Shuang-Lin, Wei Zhiyong, Sun Run-Cang
doi:10.1016/j.compositesb.2023.111013
通过铜催化综合氢解和化学功能化实现草本木质素的价值化
Lignin is an important biomass resource to replace petrochemical industry for carbon neutrality. However, it is challenged by unyielding the trade-off between activity and selectivity owing to the chemical complexity and inherent heterogeneity of lignin biomacromolecule. Herein, we report that copper nanomaterial (CuO/C) derived from metal-organic framework (HKUST-1) could effectively catalytic hydrogenolysis of herbaceous plants into monomeric phenols (up to 29.5 wt%) through a lignin-first strategy, affording methyl 3-(4-hydroxyphenyl) propionate (1-H) and methyl 3-(4-hydroxy-3-methoxyphenyl) propionate (2-G) as the main monophenols with high selectivity of 31.9% and 17.3%. Moreover, we proposed two synthetic routes based on the purification and functionalization of those two compounds (1-H and 2-G) to synthesis 3-(4-carboxyphenyl) propionic acid and functional polyesters. Subsequent studies revealed that the temperature of 50% mass loss of the two polyesters reached 430–440 °C, indicating their robust thermal stability; while the DSC curves showed the difference between the two polymers in glass conversion temperature (Tg) and crystallization. In brief, this work opens a new avenue for the production of lignin-derived chemicals and materials.
木质素是一种重要的生物质资源,可替代石化工业实现碳中和。然而,由于木质素生物大分子的化学复杂性和内在异质性,它面临着活性和选择性之间难以权衡的挑战。在此,我们报告了源自金属有机框架(HKUST-1)的纳米铜材料(CuO/C)可通过木质素优先策略有效地催化草本植物氢解为单体酚(高达 29.5 wt%),得到 3-(4-羟基苯基)丙酸甲酯(1-H)和 3-(4-羟基-3-甲氧基苯基)丙酸甲酯(2-G)作为主要的单体酚,其选择性高达 31.9% 和 17.3%。此外,我们还提出了基于这两种化合物(1-H 和 2-G)的纯化和功能化的两条合成路线,以合成 3-(4-羧基苯基)丙酸和功能性聚酯。随后的研究发现,这两种聚酯的 50% 质量损失温度达到了 430-440 ℃,表明它们具有很强的热稳定性;而 DSC 曲线则显示了两种聚合物在玻璃转化温度 (Tg) 和结晶方面的差异。简而言之,这项工作为生产木质素衍生化学品和材料开辟了一条新途径。
Construction of C/SiC–Cu3Si–Cu interpenetrating composites for long-duration thermal protection at 2500 °C by cooperative active-passive cooling
Wu Yue, Zhao Rida, Liang Bin, Pang Shengyang, Hu Chenglong, Li Jian, Cheng Hui–Ming, Tang Sufang
doi:10.1016/j.compositesb.2023.111015
通过主动-被动协同冷却构建用于 2500 ℃ 长时间热保护的 C/SiC-Cu3SiCu 互穿复合材料
Developing materials which can resist long-term ablation at ultra-high temperatures above 2200 °C in oxygen-containing environments is of prime importance for the thermal protection of aerospace vehicles, but remains a great challenge. C/SiC composites are attractive candidates for long-term use, but they are often severely ablated above 1650 °C due to the damage of protective oxide scale. Here, C/SiC–Cu3Si–Cu interpenetrating composites with interconnected ceramic and metal matrixes are developed by the selective ceramization of carbon-fiber reinforced carbon aerogel preforms. The heat radiation of C/SiC–Cu3Si–Cu, transpiration of Cu2O, evaporation of SiO2, as well as inhibition of oxygen diffusion in the glassy scale, jointly lead to the cooperative active-passive cooling during ablation. Resultantly, their surface temperatures are 150 °C, 450 °C and 750 °C lower than those for C/SiC (1900 °C, 2200 °C and 2500 °C) with a duration of 600 s ablation, respectively. They also exhibit remarkably low mass and linear ablation rates with respective 0.054–0.064 mg cm−2 s−1 and -0.157–0.018 μm s−1. Additionally, the composites can endure 1160 s ablation with a surface temperature of 1750 °C under the ablation condition where the surface temperature of C/SiC is 2200 °C. The developed C/SiC–Cu3Si–Cu interpenetrating composites are so far the only known light-weight (<3.0 g cm−3), non-ablation materials which can offer long-duration (≥600 s) thermal protection at 2200–2500 °C in high-enthalpy-flow and oxidizing environments.
开发能够在含氧环境中抵抗 2200 °C 以上超高温长期烧蚀的材料对于航空航天飞行器的热保护至关重要,但这仍然是一项巨大的挑战。C/SiC 复合材料是长期使用的理想材料,但由于保护性氧化物鳞片的破坏,它们在 1650 ℃ 以上通常会发生严重烧蚀。在这里,通过对碳纤维增强碳气凝胶预制件进行选择性陶瓷化,开发出了陶瓷和金属基体相互连接的 C/SiC-Cu3Si-Cu 互穿复合材料。在烧蚀过程中,C/SiC-Cu3Si-Cu 的热辐射、Cu2O 的蒸发、SiO2 的蒸发以及玻璃鳞片对氧扩散的抑制共同导致了主动-被动冷却。因此,在 600 秒的烧蚀持续时间内,它们的表面温度分别比 C/SiC 低 150 ℃、450 ℃ 和 750 ℃(1900 ℃、2200 ℃ 和 2500 ℃)。它们还表现出极低的质量和线性烧蚀率,分别为 0.054-0.064 mg cm-2 s-1 和 -0.157-0.018 μm s-1。此外,在 C/SiC 表面温度为 2200 ℃ 的烧蚀条件下,复合材料可承受 1160 秒的烧蚀,表面温度为 1750 ℃。所开发的 C/SiC-Cu3Si-Cu 互穿复合材料是迄今为止已知的唯一一种轻质(<3.0 g cm-3)、非烧蚀材料,可在 2200-2500 ℃ 的高焓流和氧化环境中提供长时间(≥600 秒)的热保护。
Insight into tuning of ZrO2 distribution and mechanical properties of directionally solidified Al2O3/(5Re0.2)AG/ZrO2 eutectic ceramic composites
Zhong Yujie, Li Zhe, Wang Xu
doi:10.1016/j.compositesb.2023.111016
定向凝固 Al2O3/(5Re0.2)AG/ZrO2 共晶陶瓷复合材料的 ZrO2 分布和力学性能调控透视
A novel Al2O3/(Y0.2Er0.2Yb0.2Ho0.2Lu0.2)3Al5O12((5Re0.2)AG)/ZrO2 eutectic high entropy oxide ceramic composites (HEOCs) was prepared by the directional solidification technique. The Al2O3/(5Re0.2)AG/ZrO2 eutectic HEOCs had a refined microstructure and different crystallographic orientation relationships of <10-10>Al2O3 || <103>(5Re0.2)AG || <100>ZrO2, {11–20}Al2O3 || {100}(5Re0.2)AG || {100}ZrO2, {0001} Al2O3 || {103}(5Re0.2)AG || {100}ZrO2 compared to Al2O3/YAG/ZrO2 eutectic ceramic composites. ZrO2 was distributed more uniformly and dispersedly in Al2O3/(5Re0.2)AG/ZrO2 eutectic HEOCs than in Al2O3/YAG/ZrO2 due to the similar volume strain of Al2O3/(5Re0.2)AG, (5Re0.2)AG/ZrO2 and Al2O3/ZrO2. As a result, mechanical performance including hardness, elastic modulus, and fracture toughness had been greatly improved because of the refined microstructure, tailored interfacial structure, and homogeneous distribution of ZrO2 caused by the introduction of the high entropy (5Re0.2)AG.
通过定向凝固技术制备了新型 Al2O3/(Y0.2Er0.2Yb0.2Ho0.2Lu0.2)3Al5O12((5Re0.2)AG)/ZrO2 共晶高熵氧化物陶瓷复合材料(HEOCs)。Al2O3/(5Re0.2)AG/ZrO2共晶高熵氧化物陶瓷复合材料具有精细的微观结构和不同的晶体取向关系:<10-10>Al2O3 || <103>(5Re0.2)AG||<100>ZrO2、{11-20}Al2O3 ||{100}(5Re0.2)AG ||{100}ZrO2 、{0001}Al2O3 ||{103}(5Re0.2)AG ||{100}ZrO2 与 Al2O3/YAG/ZrO2 共晶陶瓷复合材料相比。由于 Al2O3/(5Re0.2)AG、(5Re0.2)AG/ZrO2 和 Al2O3/ZrO2 的体积应变相似,因此与 Al2O3/YAG/ZrO2 相比,ZrO2 在 Al2O3/(5Re0.2)AG/ZrO2 共晶 HEOC 中的分布更加均匀和分散。因此,由于引入了高熵 (5Re0.2)AG 使微观结构更精细、界面结构更合理、ZrO2 分布更均匀,包括硬度、弹性模量和断裂韧性在内的机械性能得到了极大改善。
Recent advances on stimuli-responsive biopolymer-based nanocomposites for drug delivery
Xiao Renhua, Zhou Guangying, Wen Yuming, Ye Junhu, Li Xiaoyun, Wang Xiaoying
doi:10.1016/j.compositesb.2023.111018
用于给药的刺 激响应型生物聚合物基纳米复合材料的最新进展
Drug delivery plays a crucial part in medical therapy, where stimuli-responsive nanocarriers exhibit high delivery efficacy through changing their physicochemical properties in response to in vivo or external stimuli. In particular, biopolymer-based nanocomposites have attracted great attention as drug carriers due to their good biocompatibility, biodegradation, easy modification, low immunogenicity, and so on. They can be designed to transform size, charge and/or stability to prolong the blood circulation, accumulate at the diseased site, penetrate in tissues, internalize to target cells, and finally deliver and control drug release on demand under endogenous stimuli (e.g., acidic pH, enzymes and GSH), exogenous stimuli (e.g., temperature, light, magnetic field, and ultrasound), and both endogenous and exogenous stimuli. Different from the reviews on stimuli-responsive nanocomposites based on single biopolymer or general ideas of biopolymer-based nanocomposites, this paper summarizes strategies and recent progress of stimuli-responsive nanocomposites based on biopolymers such as polysaccharides (chitosan, hyaluronic acid, alginate, cyclodextrin, starch and cellulose) and proteins (gelatin, silk fibroin and collagen), and details their fabrication and application in drug delivery. Furthermore, this review provides evidence and ideas for designing stimuli-responsive nanocomposites for drug delivery.
药物输送在医学治疗中起着至关重要的作用,刺 激响应型纳米载体通过改变其物理化学特性来响应体内或外部刺 激,从而表现出较高的输送效果。其中,生物聚合物基纳米复合材料因其良好的生物相容性、生物降解性、易修饰性、低免疫原性等特点,作为药物载体备受关注。在内源性刺 激(如酸性 pH 值、酶和 GSH)、外源性刺 激(如温度、光、磁场和超声波)以及内源性和外源性刺 激的作用下,纳米复合材料可以通过改变尺寸、电荷和/或稳定性来延长血液循环、在病变部位积聚、穿透组织、内化为靶细胞,并最终按需递送和控制药物释放。与基于单一生物聚合物的刺 激响应纳米复合材料的综述或基于生物聚合物的纳米复合材料的一般观点不同,本文总结了基于多糖(壳聚糖、透明质酸、海藻酸、环糊精、淀粉和纤维素)和蛋白质(明胶、蚕丝纤维素和胶原蛋白)等生物聚合物的刺 激响应纳米复合材料的策略和最新进展,并详细介绍了其制备和在药物输送中的应用。此外,本综述还为设计用于给药的刺 激响应型纳米复合材料提供了证据和思路。
Additive Manufacturing of Polyaryletherketone (PAEK) polymers and their composites
Yap Timothy, Heathman Nathaniel, Phillips Tim, Beaman Joseph, Tehrani Mehran
doi:10.1016/j.compositesb.2023.111019
聚芳醚酮 (PAEK) 聚合物及其复合材料的增材制造
Polyaryletherketone (PAEK) polymers are unique thermoplastics certified for aerospace and biomedical applications, demonstrating exceptional thermo-mechanical characteristics and superior chemical resistance. They are adaptable to material extrusion (ME) and laser powder bed fusion (L-PBF) additive manufacturing systems. While various PAEK grades for additive manufacturing (AM) exist, their printing suitability, especially inter-layer strength, is not well-understood. Adding small amounts of short carbon fibers to PAEKs enhances their stiffness and service temperature but modifies their processing, structure, and properties. This study examines the effects of the AM method (L-PBF and ME) and carbon fiber addition on the structure, mechanical properties, and crystallinity of three different PAEK polymers. We characterize and correlate tensile properties, fracture modes, degree of crystallinity, fiber length and orientations, and porosity of the samples. Our findings aim to refine AM processes and feedstock materials for semi-crystalline polymers and their composites, offering insights for designing robust, economical AM parts.
聚芳醚酮(PAEK)聚合物是一种独特的热塑性塑料,经认证可用于航空航天和生物医学领域,具有优异的热机械特性和出色的耐化学性。它们适用于材料挤压(ME)和激光粉末床熔融(L-PBF)增材制造系统。虽然有各种用于增材制造(AM)的 PAEK 牌号,但它们的打印适用性,尤其是层间强度,还没有得到很好的了解。在 PAEK 中添加少量短碳纤维可提高其刚度和使用温度,但会改变其加工、结构和性能。本研究探讨了 AM 方法(L-PBF 和 ME)和碳纤维添加对三种不同 PAEK 聚合物的结构、机械性能和结晶度的影响。我们对样品的拉伸性能、断裂模式、结晶度、纤维长度和取向以及孔隙率进行了表征和关联分析。我们的研究结果旨在完善半结晶聚合物及其复合材料的 AM 工艺和原料材料,为设计坚固、经济的 AM 部件提供启示。
EGCG modified small intestine submucosa promotes wound healing through immunomodulation
Nie Rong, Zhang Qing-Yi, Tan Jie, Feng Zi-Yuan, Huang Kai, Sheng Ning, Jiang Yan-Lin, Song Yu-Ting, Zou Chen-Yu, Zhao Long-Mei, Li He-Xi, Wang Rui, Zhou Xing-Li, Hu Juan-Juan, Wu Chen-Yu, Li-Ling Jesse, Xie Hui-Qi
doi:10.1016/j.compositesb.2023.111005
经 EGCG 修饰的小肠黏膜下层通过免疫调节促进伤口愈合
Decellularized porcine small intestinal submucosa (SIS) has shown promising therapeutic efficacy as a functional wound dressing. Nevertheless, its limited anti-oxidative and immunomodulatory capacities have restricted its application for the treatment of complex skin wounds. Herein, epigallocatechin gallate (EGCG), a polyphenolic compound, was employed for the modification of the SIS to overcome such shortcomings. The EGCG-modified SIS (E-SIS) has shown excellent biocompatibility and improved hydrophilicity for cell adhesion. Notably, in vitro studies showed that the E-SIS could effectively alleviate oxidative stress and facilitate the M1-to-M2 phenotype transition of macrophages, thereby creating a favorable immune microenvironment for cell proliferation, migration, collagen synthesis as well as angiogenesis. A full-thickness skin defect model, combined with macrophage depletion, has further confirmed that the E-SIS could accelerate skin wound repair through immunomodulation in vivo. This suggested that the EGCG modification could provide a facile yet effective method to broaden the applications of the SIS for skin wound management.
脱细胞猪小肠粘膜下层(SIS)作为一种功能性伤口敷料已显示出良好的治疗效果。然而,由于其抗氧化和免疫调节能力有限,限制了其在治疗复杂皮肤伤口方面的应用。本文采用表没食子儿茶素没食子酸酯(EGCG)这种多酚化合物对 SIS 进行改性,以克服这些缺点。表没食子儿茶素没食子酸酯修饰的 SIS(E-SIS)具有良好的生物相容性,并改善了细胞粘附的亲水性。值得注意的是,体外研究表明,E-SIS 能有效缓解氧化应激,促进巨噬细胞的 M1-M2 表型转化,从而为细胞增殖、迁移、胶原蛋白合成和血管生成创造有利的免疫微环境。全厚皮肤缺损模型结合巨噬细胞耗竭进一步证实,E-SIS 可通过体内免疫调节加速皮肤伤口修复。这表明,对 EGCG 进行改性可以提供一种简便而有效的方法,扩大 SIS 在皮肤伤口管理方面的应用。
Controllable deformation design for 4D-printed active composite structure: Optimization, simulation, and experimental verification
Peng Xiang, Liu Guoao, Wang Jun, Li Jiquan, Wu Huaping, Jiang Shaofei, Yi Bing
doi:10.1016/j.compscitech.2023.110265
4D 打印活性复合材料结构的可控变形设计:优化、模拟和实验验证
Through integrating active composites and 4D printing techniques, active composites can achieve the pre-designed complex deformations. However, the tremendous design space of multiple materials brings the challenges of finding the optimum material distributions accurately, and the consistencies between simulated optimum results and actual experimental structures. Therefore, the controllable deformation design framework is proposed to guide the inverse design of 4D-printed active composite structure. The material properties of polylactic acid (PLA) and thermoplastic polyurethane (TPU) are tested and integrated into forward deformation analysis to improve the prediction accuracy of finite element analysis (FEA). An optimization integration framework with genetic algorithm is developed to optimize the material distribution and external displacement simultaneously to achieve the target deformation. Several voxelized beams and flower structures are used as engineering cases. The simulated and experimental deformation shapes and recovery shapes for the optimum structures are consistent with the target deformations. The mean squared errors (MSEs) of experimental shape and simulation shape are 0.62 mm and 0.27 mm for flower structures. These results show that the proposed methodology can obtain target deformation in simulation and experimental tests simultaneously, which can be applied into the flexible deformation design of complex active composite structures in the future.
通过将活性复合材料与 4D 打印技术相结合,活性复合材料可以实现预先设计的复杂变形。然而,多种材料的巨大设计空间带来了如何准确找到最佳材料分布以及模拟最佳结果与实际实验结构之间一致性的挑战。因此,本文提出了可控变形设计框架来指导 4D 打印活性复合材料结构的逆向设计。测试了聚乳酸(PLA)和热塑性聚氨酯(TPU)的材料特性,并将其纳入正向变形分析,以提高有限元分析(FEA)的预测精度。利用遗传算法开发了一个优化集成框架,可同时优化材料分布和外部位移,以实现目标变形。多个体素化梁和花结构被用作工程案例。优化结构的模拟和实验变形形状和恢复形状与目标变形一致。花朵结构的实验形状和模拟形状的均方误差(MSE)分别为 0.62 毫米和 0.27 毫米。这些结果表明,所提出的方法可以在模拟和实验测试中同时获得目标变形,未来可应用于复杂主动复合材料结构的柔性变形设计。
A strength based thermo-mechanical coupled cohesive zone model for simulating heat flux induced interface debonding
Shi Tianxiang, Zhang Yongqiang, Zhang Xin, Wang Yangyang, Zheng Kehong
doi:10.1016/j.compscitech.2023.110255
基于强度的热机械耦合内聚区模型,用于模拟热通量诱导的界面剥离
A thermo-mechanical strength based cohesive zone model is proposed to simulate the behaviour of an imperfect interface. In this model, the load transfer behaviour is described by the strength model rather than the traditional traction-separation law, and the heat transfer behaviour is delineated by the interface conductance including the bonding conductance, the air conductance and the contact conductance. A new damage state variable is introduced in the derivation, which needs to be updated even during the elastic stage. A reasonable assumption is made to reduce the dimension of the failure surface to simplify the model. The proposed model is validated by the comparison of the simulating results and experimental data. It is concluded that the thermo-mechanical strength based cohesive zone model provides the interaction mechanism between interface load and heat transfer and can effectively simulate the interface behaviour at various temperatures.
本文提出了一种基于热机械强度的内聚区模型,用于模拟不完全界面的行为。在该模型中,载荷传递行为由强度模型而非传统的牵引分离定律来描述,热传递行为由界面电导(包括结合电导、空气电导和接触电导)来描述。在推导过程中引入了一个新的损伤状态变量,即使在弹性阶段也需要更新。为了简化模型,我们合理地假设减小了破坏面的尺寸。模拟结果与实验数据的对比验证了所提出的模型。结论是基于热机械强度的内聚区模型提供了界面载荷和热传递之间的相互作用机制,可以有效模拟不同温度下的界面行为。
Novel fabrication of hydrophobic poly(p-phenylene terephthalamide) paper with superior tear strength and high dielectric breakdown strength
Li Na, Song Shubin, Yu Junrong, Wang Yan, Hu Zuming
doi:10.1016/j.compscitech.2023.110266
具有优异撕裂强度和高介电击穿强度的新型疏水性聚(对苯二甲酰对苯二胺)纸的制造方法
Complicated manufacture of poly(p-phenylene terephthalamide) (PPTA) paper limits its wider application. In this study, the facile gelation process was proposed to fabricate PPTA paper by injecting spontaneous-gelling low molecular weight PPTA (LMW-PPTA) solution onto the surface of non-woven PPTA fabric composed of chopped PPTA fibers. Subsequently, the PPTA papers and hydrophobic poly(vinylidene fluoride) (PVDF) doped PPTA paper were eventually obtained by gelation, washing and pressing. The mechanical properties, electric insulation property and hydrophobicity of PPTA papers were apparently affected by the ratio of chopped PPTA fibers to LMW-PPTA polymers and the content of PVDF in the paper. Significantly, the facile-process and low-cost composite PPTA papers were proved with high tear strength, preeminent dielectric breakdown strength, great thermal stability and superior hydrophobicity, which shed light on a promising direction for developing high-performance insulating materials and honeycomb materials.
聚对苯二甲酰对苯二胺(PPTA)纸制造工艺复杂,限制了其广泛应用。本研究提出了一种简便的凝胶化工艺,将自发凝胶化的低分子量聚对苯二甲酰对苯二胺(LMW-PPTA)溶液注入由切碎的聚对苯二甲酰对苯二胺(PPTA)纤维组成的非织造聚对苯二甲酰对苯二胺(PPTA)织物表面,从而制成聚对苯二甲酰对苯二胺(PPTA)纸。随后,通过凝胶化、洗涤和压制,最终得到 PPTA 纸和掺杂疏水性聚偏二氟乙烯(PVDF)的 PPTA 纸。PPTA 纸的机械性能、电绝缘性能和憎水性明显受到切碎的 PPTA 纤维与 LMW-PPTA 聚合物的比例以及纸中 PVDF 含量的影响。结果表明,这种工艺简便、成本低廉的 PPTA 复合纸具有很高的撕裂强度、优异的介电击穿强度、良好的热稳定性和优异的憎水性,为开发高性能绝缘材料和蜂窝材料指明了方向。