今日更新:Composite Structures 1 篇,Composites Part A: Applied Science and Manufacturing 4 篇,Composites Part B: Engineering 2 篇
Multiscale finite element modeling of origami-inspired dual matrix deployable composite with visco-hyperelastic hinge
Adnan Ahmed, Israr Ud Din, Siddhesh Kulkarni, Kamran A. Khan
doi:10.1016/j.compstruct.2024.118301
带有粘弹性铰链的折纸启发式双基质可展开复合材料的多尺度有限元建模
Dual matrix deployable composites with viscoelastic materials are prone to experiencing relaxation in their stored strain energy, leading to potential degradation in their deployment performance. This study presents a multiscale FE modeling approach to investigate the folding and deployment behavior of origami inspired dual-matrix deployable composite with visco-hyperelastic hinge. A typical dual-matrix origami composite fold was manufactured using a hot compression molding technique and hand layup method and folding tests were carried out. The visco-hyperelastic behavior of elastomer used in the folding region was characterized. Experiments were carried out on elastomer under rate dependent loading, single-step, multi-step, and cyclic tests and material parameters for constitutive model were identified. The homogenized properties of hybrid laminate and elastomer laminate were obtained from XCT-driven FE based homogenization of real RVE. First, the multiscale FE model was validated with the experimentally-measured moment-curvature diagram. Next, the proposed multiscale FE model was employed to simulate the influence of modulus relaxation of pure elastomer on the deployment behavior of a simple rectangular fold and an origami-inspired waterbomb base structure. The variation of moment-curvature, and relaxation in strain energies during stowage under controlled and free deployment are reported. The effect of incomplete folding and stowage durations on strain energy and deployment time was investigated. In the end, the influence of the loading rate effect on the bending stiffness relaxation of pure elastomer and elastomer laminate fold was investigated.
采用粘弹性材料的双基体可展开复合材料很容易出现存储应变能的松弛,从而导致其展开性能的潜在退化。本研究提出了一种多尺度有限元建模方法,用于研究具有粘弹性铰链的折纸双基质可展开复合材料的折叠和展开行为。采用热压成型技术和手糊方法制造了典型的双基质折纸复合材料折叠件,并进行了折叠测试。对折叠区域所用弹性体的粘弹性行为进行了表征。对弹性体进行了速率相关加载、单步、多步和循环试验,并确定了构成模型的材料参数。混合层压板和弹性体层压板的均质化特性是通过基于 XCT 驱动的实际 RVE FE 均质化获得的。首先,用实验测量的弯矩曲率图验证了多尺度 FE 模型。接着,利用所提出的多尺度有限元模型模拟了纯弹性体模量松弛对简单矩形折叠和受折纸启发的水弹底座结构的展开行为的影响。报告了在受控和自由展开情况下收放过程中的力矩曲率变化和应变能量松弛。研究了不完全折叠和收放持续时间对应变能和展开时间的影响。最后,研究了加载速率对纯弹性体和弹性体层压折叠弯曲刚度松弛的影响。
Mechanical behavior and apparent stiffness of flax, hemp and nettle fibers under single fiber transverse compression tests
Jason Govilas, Anouk Chevallier, Wajih Akleh, Johnny Beaugrand, Cédric Clévy, Vincent Placet
doi:10.1016/j.compositesa.2024.108321
亚麻、大 麻和荨麻纤维在单纤维横向压缩试验中的机械行为和表观刚度
While plant fibers find extensive use across numerous applications, their transverse behavior and mechanical properties lack direct and fiber-scale characterization, posing a significant knowledge gap. This paper investigates, for the first time, the transverse behavior of flax, hemp and nettle fibers through Single Fiber Transverse Compression Tests (SFTCTs). Finite element analysis is used to study the influence of time-dependent and irreversible inelastic behavior on the fiber’s response and identify configurations fit for the identification of apparent elastic properties. SFTCTs are performed experimentally with a repeated progressive loading protocol using a custom micro-mechatronic setup. An apparent fiber transverse elastic modulus of 1 to 3 GPa is identified by inverse method for all tested fibers, demonstrating high fiber anisotropy. Important inelastic features are also observed on fiber behavior. Their origin is discussed with both material behavior and structural mechanisms such as lumen collapse, identified as the main potential causes.
虽然植物纤维在众多应用领域都有广泛应用,但它们的横向行为和机械特性却缺乏直接的纤维尺度表征,这构成了一个重大的知识空白。本文首次通过单纤维横向压缩试验(SFTCT)研究了亚麻、大 麻和荨麻纤维的横向行为。有限元分析用于研究随时间变化和不可逆的非弹性行为对纤维响应的影响,并确定适合识别表观弹性特性的配置。使用定制的微型机电一体化装置,通过重复渐进加载协议进行 SFTCT 实验。所有测试纤维的表观纤维横向弹性模量均通过反演法确定为 1 至 3 GPa,表明纤维的各向异性很高。在纤维行为中还观察到重要的非弹性特征。我们讨论了它们的起源,并将材料行为和结构机制(如内腔塌陷)确定为主要的潜在原因。
Effect of plasma treatment on hygrothermal creep behaviour of flax fibre composite
Jianqun Hao, Julien Bardon, Grégory Mertz, C.A. Rojas, Aart Willem Van Vuure
doi:10.1016/j.compositesa.2024.108322
等离子处理对亚麻纤维复合材料湿热蠕变行为的影响
Atmospheric plasma activation and plasma coating with 3-aminopropyltriethoxysilane (APTES) were used to investigate the effect of a modified interface on the creep behaviour of flax fibre reinforced polyoxymethylene composite. The wetting parameters and the interfacial shear strength indicate that using air-based plasma activation is superior to plasma coating with APTES when improvement of interface and mechanical properties are concerned. Hygrothermal creep tests within the linear viscoelastic region reveal that the creep resistance of air plasma treated composites is significantly enhanced, evidenced by reduced instantaneous strain and slower viscoelastic flow when compared to the untreated composites. However, creep rupture (run to failure) tests demonstrate that the air plasma treatment extends the creep lifespan only under standard conditions (50 % RH and 23 °C). Under severe conditions (85 % RH and 23 °C), plasma-treated composites exhibit a somewhat shorter lifespan, possibly because some damage induced by the plasma treatment is exacerbated at high humidity.
研究人员利用大气等离子活化和 3-aminopropyltriethoxysilane (APTES) 等离子涂层研究了改性界面对亚麻纤维增强聚甲醛复合材料蠕变行为的影响。润湿参数和界面剪切强度表明,在改善界面和机械性能方面,使用气基等离子活化优于使用 APTES 的等离子涂层。线性粘弹性区域内的湿热蠕变测试表明,与未经处理的复合材料相比,经过空气等离子体处理的复合材料的抗蠕变性明显增强,表现为瞬时应变降低,粘弹性流动减慢。然而,蠕变断裂(运行至失效)测试表明,空气等离子处理仅在标准条件下(50 % 相对湿度和 23 °C)延长了蠕变寿命。在苛刻条件下(85 % 相对湿度和 23 °C),经过等离子处理的复合材料的寿命稍短,这可能是因为在高湿度条件下,等离子处理引起的某些损坏会加剧。
Lightweight polyimide composite foams with anisotropic hierarchical pore structure for enhanced mechanical, flame retardancy and thermal insulation purposes
Long Ni, Yinfu Luo, Junyu Lu, Hang Ye, Liwei Yan, Mei Liang, Shengtai Zhou, Huawei Zou
doi:10.1016/j.compositesa.2024.108325
具有各向异性分层孔隙结构的轻质聚酰亚胺复合泡沫,可增强机械性能、阻燃性和隔热性能
In this study, lightweight polyimide foam (PIF) with anisotropic pore structure were fabricated by adopting microwave-assisted foaming technique. Afterward, lightweight PIF/PI aerogel/silica aerogel (PIF/PIA/SiA) with anisotropic hierarchical pore structures was prepared by impregnation and directional freeze-drying method. The directional growth of foam pores and ice crystals endowed PIF/PIA/SiA with anisotropic skeleton structures and hierarchical porous filling structures, leading to anisotropic mechanical and thermal insulation performances. PIF/PIA/SiA presented mechanical robustness in vertical direction and mechanical flexibility in horizontal direction due to its unique pore structure. In addition, PIF/PIA/SiA showed outstanding thermal stability and flame retardancy, suggesting a promising application in the field of high temperature fire protection. The PIF/PIA/SiA exhibited superior thermal insulation performance with thermal conductivities ranging from 0.0253 to 0.0523 W/(m·K) between 25 and 300 °C. Therefore, a facile strategy was developed to fabricate PIF-based composite foams for mechanical, flame retardancy and thermal insulation applications in high-end engineering fields.
本研究采用微波辅助发泡技术制备了具有各向异性孔结构的轻质聚酰亚胺泡沫(PIF)。随后,采用浸渍和定向冻干方法制备了具有各向异性分层孔隙结构的轻质 PIF/PI 气凝胶/二氧化硅气凝胶(PIF/PIA/SiA)。泡沫孔隙和冰晶的定向生长赋予了 PIF/PIA/SiA 各向异性的骨架结构和分层多孔填充结构,使其具有各向异性的机械和隔热性能。由于其独特的孔隙结构,PIF/PIA/SiA 在垂直方向上具有机械坚固性,在水平方向上具有机械柔韧性。此外,PIF/PIA/SiA 还具有出色的热稳定性和阻燃性,在高温防火领域具有广阔的应用前景。PIF/PIA/SiA 具有优异的隔热性能,在 25 至 300 °C 之间的导热系数为 0.0253 至 0.0523 W/(m-K)。因此,我们开发出了一种简便的策略来制造基于 PIF 的复合泡沫,用于高端工程领域的机械、阻燃和隔热应用。
Experimental investigation of stacking interface on mode II interlaminar behaviour of self-healable vitrimeric CFRP
Yang Zhao, Menglin Zhao, Siyuan Wang, Anyang Wang, Zhengping Chang, Zhongqi Wang
doi:10.1016/j.compositesa.2024.108326
堆叠界面对自修复玻璃纤维增强塑料层间行为模式 II 的实验研究
With the extensive research on ester-exchanged vitrimer, laminates utilizing vitrimer as matrix have garnered increasing attention due to their healability for achieving long-term durability of the composite structure. However, current research on the healing of mode II delamination for vitrimeric CFRP (vCFRP) laminates remains notably limited. In this study, the ENF tests were implemented to acquire load–displacement curves of eight typical vCFRP laminates with various interfaces. The results indicated a pronounced impact of the stacking interface on the fracture toughness values, the R-curves, fiber bridging effect, and crack growth behaviours. The continuous 0° fiber hindered the upward migration for the laminates with 0°//0° interface, while the discontinuous θ1° fabric had a lower in-plane strength and were more prone to cracking for the laminates with θ1°//θ2° interface. Subsequently, the healing efficiencies of specimens were characterized. The healed laminates undergone three shear delamination damages could still achieve a substantial recovery of about 76.33%.
随着酯交换玻璃纤维聚合物研究的广泛开展,以玻璃纤维聚合物为基体的层压板因其可愈合性而受到越来越多的关注,以实现复合材料结构的长期耐久性。然而,目前有关玻璃纤维增强塑料(vCFRP)层压板模式 II 分层愈合的研究仍然非常有限。在本研究中,采用 ENF 试验获取了八种具有不同界面的典型 vCFRP 层压板的载荷-位移曲线。结果表明,堆叠界面对断裂韧性值、R 曲线、纤维桥接效应和裂纹生长行为有明显影响。在 0°//0° 接口的层压板中,连续的 0° 纤维阻碍了裂纹的上移;而在 θ1°//θ2° 接口的层压板中,不连续的 θ1° 纤维的面内强度较低,更容易开裂。随后,对试样的愈合效率进行了表征。经过三次剪切分层破坏后,愈合后的层压板仍能实现约 76.33% 的大幅恢复。
Experimental study on the effect of waviness defects on composite material impact dynamics
E.Y.H. Chai, W.C. Wang, W.J.R. Christian
doi:10.1016/j.compositesb.2024.111638
波状缺陷对复合材料冲击动力学影响的实验研究
The effect of pre-existing defects in composite materials on impact tolerance is poorly understood. In this study, carbon fibre reinforced polymers with waviness defects were used to explore how pre-existing defects affect impact events. An algorithm was introduced to provide insights into damage mechanics during impact experiments using damage-time maps. These maps provide information on damage: location, severity and initiation time. The morphology of damage measured using damage-time maps were compared with measurements from pulse-echo ultrasound and found to have a high level of agreement. This study found severe waviness bands acted as a barrier preventing delamination growth, resulting in a unique damage shape without causing higher damage area. By using the introduced algorithm, the amount of time required to understand complex impact events is substantially reduced.
人们对复合材料中预先存在的缺陷对冲击耐受性的影响知之甚少。在这项研究中,使用了具有波状缺陷的碳纤维增强聚合物来探索预先存在的缺陷如何影响冲击事件。研究引入了一种算法,利用损伤时间图深入了解冲击实验过程中的损伤力学。这些图提供了有关损伤的信息:位置、严重程度和起始时间。使用损伤时间图测量的损伤形态与脉冲回波超声测量结果进行了比较,发现两者具有很高的一致性。这项研究发现,严重的波状带起到了阻止分层生长的作用,从而形成了独特的损伤形状,但不会造成更大的损伤面积。通过使用引入的算法,了解复杂撞击事件所需的时间大大减少。
Bioinspired, Highly Sensitive Interlocked Flexible Textile Pressure Sensor Based on Multilayer SWCNTs/PVP/rGO Dendritic for Gesture Recognition
Yong-song Tan, Weiyi Han, You Wu, Dajiang Kuang, Liyang Song, Chaoxia Wang
doi:10.1016/j.compositesb.2024.111639
基于多层 SWCNTs/PVP/rGO 树枝状结构的生物启发、高灵敏度互锁柔性纺织品压力传感器,可用于手势识别
The development of wearable gesture recognition systems, capable of converting intricate human gestures into electric signals and graphical representations, poses significant challenges for future advancements in health monitoring and human-machine interfaces. In response to this demand, we present an approach centered on a cell-inspired, multiscale hierarchical structural piezoresistive pressure sensor designed for gesture recognition applications. The breathable, hierarchically interlocked textile pressure sensor (PFPA), featuring a SWCNTs/polyvinylpyrrolidone (PVP)/reduced graphene oxide (rGO) dendritic structure combined with a PANI/PVA cylindrical array, exhibits remarkable properties. The dendritic electrodes, composed of SWCNTs and PVP in a 1:2 ratio, maintain optimal regularity. Meanwhile, the cylindrical PANI/PVA array is meticulously engineered with a radius of 200 μm, a height of 200 μm, and an inter-cylindrical spacing of 150 μm. The PFPA demonstrates an unprecedented ultrahigh sensitivity of 80.8 kPa-1 across a pressure range of 0 to 5 kPa, coupled with a rapid response time of 150 ms and minimal hysteresis of 16.1%. The PFPA also demonstrates outstanding repeatability, with no significant performance degradation observed after 4000 cycles. By correlating the bending angles of finger joints with resistance changes, we successfully integrated these sensors into a glove, enabling precise gesture recognition. The multilayer SWCNTs/PVP/rGO dendritic and PANI/PVA cylindrical array pressure sensor exhibits superior sensing performance and accurate posture capture. This demonstrates its significant potential for applications in wearable electronics and intelligent devices, marking a substantial advancement in the field.
可穿戴手势识别系统能够将复杂的人体手势转换为电信号和图形表示,它的开发对未来健康监测和人机界面的发展提出了重大挑战。针对这一需求,我们提出了一种方法,其核心是一种受细胞启发的多尺度分层结构压阻压力传感器,专为手势识别应用而设计。这种可透气的分层交错织物压力传感器(PFPA)采用了 SWCNTs/聚乙烯吡咯烷酮(PVP)/还原氧化石墨烯(rGO)树枝状结构,并结合了 PANI/PVA 圆柱阵列,具有显著的特性。树枝状电极由 SWCNTs 和 PVP 以 1:2 的比例组成,能保持最佳的规则性。同时,圆柱形 PANI/PVA 阵列经过精心设计,半径为 200 μm,高度为 200 μm,圆柱间距为 150 μm。PFPA 在 0 至 5 kPa 的压力范围内具有前所未有的 80.8 kPa-1 的超高灵敏度,同时具有 150 毫秒的快速响应时间和 16.1% 的最小滞后。PFPA 还具有出色的可重复性,在 4000 次循环后未发现明显的性能下降。通过将手指关节的弯曲角度与电阻变化相关联,我们成功地将这些传感器集成到了手套中,实现了精确的手势识别。多层 SWCNTs/PVP/rGO 树枝状和 PANI/PVA 圆柱阵列压力传感器表现出卓越的传感性能和精确的姿态捕捉。这证明了它在可穿戴电子设备和智能设备中的巨大应用潜力,标志着该领域的重大进展。