今日更新:Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 4 篇,Composites Science and Technology 1 篇
Synchrotron X-ray microtomography and finite element modelling to uncover flax fibre defect’s role in tensile performances
Delphine Quereilhac, Emmanuel De Luycker, Sofiane Guessasma, Marwa Abida, Jonathan Perrin, Timm Weitkamp, Alain Bourmaud, Pierre Ouagne
doi:10.1016/j.compositesa.2024.108276
同步加速器x射线微断层扫描和有限元建模揭示亚麻纤维缺陷在拉伸性能中的作用
Flax fibres offer performance capabilities comparable to glass fibres, thereby enhancing their potential in the biobased composites industry. However, these fibres have morphological defects affecting their mechanical features. In the present work, flax elementary fibres geometries with defects assessed by synchrotron X-ray microtomography were meshed to simulate a tensile test using finite element analysis. For the first time, the distribution of stresses in the vicinity of defects is revealed. The geometrical irregularities at the surface of the fibre and the delamination of cellulose layers within fibre cell wall turned out to concentrate stress up to 7.5 times compared to defect-free regions. These results demonstrate why flax fibres cannot reach their full potential in comparison to what could be expected from a structure mainly constituted from crystalline cellulose microfibrils, and why fracture in a composite is likely to initiate in those defect zones.
亚麻纤维提供与玻璃纤维相当的性能,从而增强了其在生物基复合材料行业的潜力。然而,这些纤维具有影响其机械特性的形态缺陷。在目前的工作中,用同步加速器x射线微断层扫描评估了亚麻初级纤维的几何形状,并用有限元分析模拟了拉伸试验。首次揭示了缺陷附近的应力分布。纤维表面的几何不规则性和纤维细胞壁内纤维素层的分层使应力集中程度达到无缺陷区域的7.5倍。这些结果表明,与主要由结晶纤维素微原纤维构成的结构相比,为什么亚麻纤维不能充分发挥其潜力,以及为什么复合材料中的断裂很可能在这些缺陷区域开始。
4D printing of cellular silicones with negative stiffness effect for enhanced energy absorption and impact protection
Xiaoyan Liu, Yaling Zhang, Yu Su, Chengzhen Geng, Yu Liu, Jiangping He, Ai Lu
doi:10.1016/j.compositesb.2024.111561
具有负刚度效应的多孔硅树脂的4D打印,增强能量吸收和冲击防护
Cellular silicone foams are renowned for their exceptional flexibility, ultra-elasticity, and durability, which have gained significant attentions in diverse applications. However, manufacturing porous silicone foams featuring substantial bending curvatures and customized mechanical properties remain a challenge. Herein, this work presents a new strategy for manufacturing curved porous silicone foams with both 4D printed bending curvature and tailored meta-mechanical properties. The foam is achieved by direct ink writing of composite silicone inks embedded with thermal expandable microspheres as foaming agents. The work studied in detail the thermal expansion of microspheres, foaming of composite silicone inks, as well as properties of the expanded foam. Utilizing the strain mismatch under thermal stimuli, the printed bilayer structures achieved shape-shifting. Additionally, silicones composed of stacked bilayer filaments exhibited negative stiffness properties under compression, leading to enhanced energy absorption capacity, which can be fine-tuned through different printing structural designs, demonstrating its potential in fields such as energy dissipation and shock absorption while protecting objects with curved shapes.
多孔硅胶泡沫以其卓越的柔韧性、超弹性和耐用性而闻名,在各种应用中得到了极大的关注。然而,制造具有大量弯曲曲率和定制机械性能的多孔硅胶泡沫仍然是一个挑战。在这里,这项工作提出了一种制造具有4D打印弯曲曲率和定制元力学性能的弯曲多孔泡沫硅的新策略。泡沫是通过嵌入热膨胀微球作为发泡剂的复合硅树脂墨水的直接墨水书写实现的。本文详细研究了微球的热膨胀、复合硅树脂油墨的发泡以及膨胀泡沫的性能。利用热刺 激下的应变失配,打印的双层结构实现了变形。此外,由堆叠的双层长丝组成的有机硅在压缩下表现出负刚度特性,从而增强了能量吸收能力,可以通过不同的印刷结构设计进行微调,从而展示了其在能量耗散和减震等领域的潜力,同时保护具有弯曲形状的物体。
Micromechanics stiffness upscaling of plant fiber-reinforced composites
Markus Königsberger, Valentin Senk, Markus Lukacevic, Michael Wimmer, Josef Füssl
doi:10.1016/j.compositesb.2024.111571
植物纤维增强复合材料的微力学刚度提升
Fiber-reinforced green composites made from natural plant fibers are an increasingly popular sustainable alternative to conventional high-performance composite materials. Given the variety of natural fibers themselves, and the even larger variety of possible composites with specific fiber dosage, fiber orientation distribution, fiber length distribution, and fiber-matrix bond characteristics, micromechanics-based modeling is essential for characterizing the macroscopic response of these composites. Herein, an analytical multiscale micromechanics model for elastic homogenization is developed, capable of capturing the this variety. The model features (i) a nanoscopic representation of the natural fibers to predict the fiber stiffness from the universal stiffness of the fiber constituents, mainly cellulose, (ii) a spring-interface model to quantify the compliance of the fiber-matrix bond, and (iii) the ability to model any (and any combination of) orientation distribution and aspect ratio distribution. Validation is performed by comparing the predicted stiffness to experimental results for as many as 73 composites available in the literature. Extensive sensitivity analyses quantify the composite stiffening upon increasing fiber volume fraction, fiber alignment, fiber length, and fiber-matrix interface stiffness, respectively.
由天然植物纤维制成的纤维增强绿色复合材料是一种越来越受欢迎的可持续替代传统高性能复合材料。考虑到天然纤维本身的多样性,以及具有特定纤维用量、纤维取向分布、纤维长度分布和纤维-基质结合特性的更多种类的可能复合材料,基于微观力学的建模对于表征这些复合材料的宏观响应至关重要。本文建立了弹性均匀化的多尺度细观力学分析模型,能够捕捉到这种变化。该模型的特点是:(1)天然纤维的纳米级表征,通过纤维成分(主要是纤维素)的普遍刚度来预测纤维的刚度;(2)弹簧界面模型,量化纤维-基质键的顺应性;(3)模拟任何(以及任何组合)取向分布和纵横比分布的能力。通过比较文献中多达73种复合材料的预测刚度和实验结果来进行验证。广泛的敏感性分析量化了复合材料在增加纤维体积分数、纤维排列、纤维长度和纤维-基体界面刚度时的刚度。
Interlaminar reinforced carbon fiber/epoxy composites by electrospun ultrafine hybrid fibers
Yuzhe Huang, Xujin Lv, Hongyu Huo, Baoyan Zhang, Gongqiu Peng, Jing Ge, Han Guo, Yong Liu
doi:10.1016/j.compositesb.2024.111578
静电纺超细混杂纤维层间增强碳纤维/环氧复合材料
The demand for high-strength composites in the aerospace industry is increasing; however, their low-impact resistance poses a danger to aircraft. Consequently, significant attention has been devoted to researching the interlaminar toughening of carbon fiber-epoxy composite laminates, focusing on electrospun fibers due to their high porosity and specific surface area. Our previous work explored the potential of poly(aryl ether nitrile) as an interlaminar toughening option. Nonetheless, these materials exhibited a decline in flexural properties. To address this concern, we developed poly(arylene ether nitrile)-poly(ε-caprolactone) ultrafine hybrid fiber membranes via electrospinning to enhance the interlaminar performance of composite laminates. The interlaminar fracture toughness demonstrated a remarkable improvement of 132.5%. Additionally, the flexural strength in-creased by at least 12.3%, while the flexural modulus experienced a minimum in-crease of 17.9%. The interlaminar shear strength improved by approximately 27%-28%, and the impact strength increased by 99.2%. This study demonstrates the significant potential of electrospun hybrid fiber membranes in improving the interlaminar properties of carbon fiber-epoxy composite laminates, con-tributing to developing safer and more durable materials for the aerospace industry.
航空航天工业对高强度复合材料的需求日益增加;然而,它们的低抗冲击性对飞机构成了危险。因此,碳纤维-环氧复合材料层间增韧的研究受到了广泛的关注,其中以电纺丝纤维为重点,因为其具有较高的孔隙率和比表面积。我们之前的工作探索了聚芳醚腈作为层间增韧选择的潜力。尽管如此,这些材料表现出弯曲性能的下降。为了解决这一问题,我们采用静电纺丝法制备了聚(芳醚腈)-聚(ε-己内酯)超细杂化纤维膜,以提高复合层压板的层间性能。层间断裂韧性显著提高132.5%。此外,抗弯强度至少增加了12.3%,而抗弯模量最小增加了17.9%。层间抗剪强度提高约27% ~ 28%,冲击强度提高99.2%。这项研究证明了静电纺混合纤维膜在改善碳纤维-环氧复合材料层间性能方面的巨大潜力,有助于为航空航天工业开发更安全、更耐用的材料。
Preparation, Cure, Characterization, and Mechanical Properties of Reactive Flame-Retardant Cyanate Ester/Epoxy Resin Blends and Their Carbon Fiber Reinforced Composites
Mustafa Mukhtar, Donald Klosterman, Alexander B. Morgan
doi:10.1016/j.compositesb.2024.111580
反应性阻燃氰酸酯/环氧树脂共混物及其碳纤维增强复合材料的制备、固化、表征和力学性能
This study explores the formulation space of flame retardant thermoset polymers, specifically involving blends of epoxy and cyanate ester (EP/CE) and a reactive phosphorus-based flame retardant, poly (m-phenylene methylphosphonate) (PMP). Two CE monomers were investigated, each blended with the same epoxy monomer (DGEBA) in a 1:1 weight ratio. The impact of phosphorus concentration on the neat (neat meaning no fibers were present) resin blends was characterized using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The flammability and mechanical characteristics were assessed using micro-combustion calorimetry (MCC) and dynamic mechanical analysis (DMA). Carbon fiber composite panels were successfully fabricated using a wet layup process and autoclave curing with a fiber volume fraction (Vf) of approximately 0.5. DMA testing of the cured composite laminates pinpointed that the average Tg of the EP/CE blend was reduced with PMP addition by up to 39 °C at a phosphorous level of 3 wt%. Cone calorimetry tests confirmed the effectiveness of the flame retardant by reducing the peak Heat Release Rate (HRR) by approximately 27%. The integration of PMP into EP/CE only marginally reduced the 3-point flexural strength (6–15%) and modulus (7–13%) relative to baseline samples.
本研究探索了阻燃热固性聚合物的配方空间,特别是涉及环氧树脂和氰酸酯(EP/CE)的共混物和活性磷基阻燃剂聚(间苯甲基膦酸酯)(PMP)。研究了两种CE单体,每一种都与相同的环氧单体(DGEBA)以1:1的重量比共混。采用差示扫描量热法(DSC)和热重分析(TGA)表征了磷浓度对纯树脂共混物(纯意味着没有纤维存在)的影响。采用微燃烧量热法(MCC)和动态力学分析(DMA)对其可燃性和力学特性进行了评价。采用湿法铺层和高压灭菌法成功制备了碳纤维复合材料板,纤维体积分数(Vf)约为0.5。固化复合材料层压板的DMA测试表明,在磷含量为3wt %的情况下,添加PMP可使EP/CE共混物的平均Tg降低高达39°C。锥形量热法测试通过将峰值热释放率(HRR)降低约27%,证实了阻燃剂的有效性。与基线样品相比,PMP与EP/CE的整合只略微降低了三点抗弯强度(6-15%)和模量(7-13%)。
Bone osteon-like structures: a biomimetic approach towards multiscale fiber-reinforced composite structures
Alessandro Stagni, Giacomo Trevisan, Laura Vergani, Flavia Libonati
doi:10.1016/j.compscitech.2024.110669
骨类骨结构:多尺度纤维增强复合材料结构的仿生方法
Natural materials show astonishing mechanical properties, despite their rather poor building blocks. This counterintuitive behavior can be traced back to their hierarchical organization that enhances the properties of the building blocks. A classic example is bone: lightweight, stiff, strong, yet tough. This property combination is attributed particularly to the microstructure, where osteons deflect and arrest cracks. In this work, we mimic the bone microstructure with fiber-reinforced composites: we perform a numerical parametric study, by varying the layup of the osteon-like structures (OLS) and interconnecting layers representing the interstitial bone lamellae, and we manufacture and test single OLS as proof of concept. Results show the key role of OLS and interconnecting layers in deflecting and arresting cracks, whereas the combination of diverse materials affects the elastic properties. Finally, the introduction of hollow OLS, not affecting fracture toughness, might be used to expand the material functionality, paving the way toward novel multifunctional composites.
天然材料表现出惊人的机械性能,尽管它们的组成成分相当差。这种违反直觉的行为可以追溯到它们的分层组织,这种组织增强了构建块的属性。一个典型的例子是骨头:轻、硬、强、韧。这种性能组合特别归因于微观结构,其中骨偏转并阻止裂纹。在这项工作中,我们用纤维增强复合材料模拟骨微观结构:我们进行了数值参数研究,通过改变骨样结构(OLS)的堆叠和代表间隙骨片的互连层,我们制造和测试了单个OLS作为概念证明。结果表明,OLS和连接层在偏转和止裂中起关键作用,而不同材料的组合影响弹性性能。最后,在不影响断裂韧性的情况下,引入空心OLS可用于扩展材料的功能,为新型多功能复合材料铺平道路。