今日更新:Composite Structures 3 篇,Composites Part A: Applied Science and Manufacturing 3 篇,Composites Science and Technology 2 篇
Extended phase field modeling of interface debonding and bulk cracking in realistic 3D printed fiber reinforced composites
Pengfei Li, Liang Xia, Yi Wu, Thi Xiu Le, Wenqiang Zuo, Sili Liu, Lunyang Zhao
doi:10.1016/j.compstruct.2024.118396
现实3D打印纤维增强复合材料界面剥离和大块开裂扩展相场模型
In this work, we shall implement a novel modeling approach to simulate interface debonding and bulk cracking in realistic 3D printed fiber reinforced composites. The materials are firstly manufactured with the Selective Laser Sintering of PA12 polymer powder embedding glass fibers and additive particles. An in-situ compression test on a cylindrical sample is conducted. X-ray Computed Tomography (XRCT) technique is employed to obtain experimental fracture images and to provide a complete 3D description of the morphology of each component for constructing a completely Realistic 3D microstructure mesh Model (R3M) . Meanwhile, an Extended Phase Field Model (EPFM) is presented considering gradient plasticity and interfacial debonding mechanisms. Following that, numerical simulations are conducted, by using the EPFM and R3M, to investigate the fracture behavior in the fiber reinforced composite. In contrast to existing works, a qualitative comparison of fracture phenomena in experiments and simulations is conducted. Anisotropic behavior of the 3D printed fiber reinforced composite is observed both in the experiments and simulations. Our results reveal that the EPFM can well capture the experimental damage phenomena, including fiber/matrix debonding, fiber breaking and pore connecting in 3D printed fiber reinforced composites, by employing the R3M where the microstructure directly arises from the experimental XRCT.
在这项工作中,我们将实现一种新的建模方法来模拟现实3D打印纤维增强复合材料的界面脱粘和大块开裂。首先采用选择性激光烧结方法将PA12聚合物粉末包埋玻璃纤维和添加剂颗粒制成材料。对圆柱形试样进行了原位压缩试验。采用x射线计算机断层扫描(XRCT)技术获取实验断裂图像,并对各部件的形貌进行完整的三维描述,构建完全逼真的三维微观结构网格模型(R3M)。同时,提出了考虑梯度塑性和界面剥离机制的扩展相场模型(EPFM)。利用EPFM和R3M进行了数值模拟,研究了纤维增强复合材料的断裂行为。与已有的研究成果相比,本文对实验和模拟中的断裂现象进行了定性比较。通过实验和模拟观察了3D打印纤维增强复合材料的各向异性行为。结果表明,EPFM可以很好地捕捉3D打印纤维增强复合材料的实验损伤现象,包括纤维/基体脱粘,纤维断裂和孔隙连接,通过使用R3M,其中微观结构直接来自实验XRCT。
Modeling impact compressive behaviors of 3D woven composites under low temperature and strain rate effect
Huihui Liu, Baozhong Sun, Bohong Gu, Meiqi Hu
doi:10.1016/j.compstruct.2024.118402
低温应变率效应下三维机织复合材料冲击压缩特性建模
Dynamic compressive damages of 3D woven composites in low temperature environments are crucial for the design of engineering structures in cryogenic applications. This study presents the compressive damage behaviors of 3D angle-interlock woven composites under low-temperatures. We developed a homogeneous model incorporating the strain rate effect and thermo-mechanical coupled constitutive relation to numerically analyze compressive damages at low temperatures. Dynamic compression tests were conducted on split Hopkinson pressure bar (SHPB) apparatus with strain rates ranging from 300 to 1500/s at temperatures of 20 °C, −40 °C, and −80 °C, respectively. We found that the compressive stiffness and strength are more temperature-sensitive along the out-of-plane direction, while they exhibit greater sensitivity to strain rate along the in-plane direction. The failure mode is characterized by shear failure along the out-of-plane and warp directions, and delamination along the weft direction. The test results and finite element analyses (FEA) show that the 3D woven composites exhibit brittleness at low temperatures and experience more severe compressive damages compared to those at room temperatures. Importantly, we observed accumulations of inelastic heat in the compressive damage zone, indicating that the compressive damages are also converted into thermal energies under low temperatures.
三维编织复合材料在低温环境下的动态压缩损伤对低温工程结构的设计至关重要。研究了三维角互锁编织复合材料在低温条件下的压缩损伤行为。建立了结合应变率效应和热-力耦合本构关系的均匀模型,对低温下的压缩损伤进行了数值分析。在分离式霍普金森压杆(SHPB)装置上进行动态压缩试验,应变速率为300 ~ 1500/s,温度分别为20 °C、- 40 °C和- 80 °C。抗压刚度和强度沿面外方向对温度更敏感,而沿面内方向对应变率更敏感。破坏模式主要表现为沿面外和经向的剪切破坏和沿纬向的分层破坏。试验结果和有限元分析表明,三维编织复合材料在低温下表现出脆性,比室温下的压缩损伤更严重。重要的是,我们在压缩损伤区观察到非弹性热的积累,这表明压缩损伤在低温下也转化为热能。
Load transfer characteristics in biocomposites reinforced by periodically graded cellulose microfibrils
Mingyang Chen, Jintao Zhu, Liao-Liang Ke
doi:10.1016/j.compstruct.2024.118404
周期性分级纤维素微原纤维增强生物复合材料的载荷传递特性
Cellulose microfibrils serve as the major load carriers for a variety of biocomposites in nature. The microfibrils possess periodically graded structures, the role of which in load transfer between the fibril and matrix is unclear. In this paper, we revisit the shear-lag theory by taking the periodically graded mechanical properties into consideration. We find that the alternating arrangement of stiff crystalline parts and compliant amorphous parts result in distinct stress distributions compared to ordinary fiber-reinforced composites. The normal stresses in the microfibrils are gradually built up from the amorphous parts to the crystalline parts. Most importantly, the interfacial shear stresses are profoundly reduced by the graded structure, and the interface damages developed due to high external loadings are more evenly distributed over the entire microfibrils instead of concentrating at the localized edge zones. Careful examinations on possible variations in configurations, including the pitch lengths of the periodical structures and the stacking patterns of the microfibrils, confirm that conclusions drawn on the shear-lag analysis are applicable to more complex scenarios. Our study indicates a possible strategy to regulate the interfacial loadings by designing proper graded structures in the reinforcements.
在自然界中,纤维素微原纤维是多种生物复合材料的主要载体。微原纤维具有周期性的梯度结构,其在纤维和基质之间的载荷传递中的作用尚不清楚。在本文中,我们重新审视剪切滞后理论,考虑周期性梯度力学性能。我们发现,与普通纤维增强复合材料相比,刚性结晶部分和柔性非晶部分的交替排列导致了明显的应力分布。微原纤维中的正常应力从无定形部分逐渐建立到结晶部分。最重要的是,梯度结构大大降低了界面剪应力,并且由于高外载荷而产生的界面损伤更均匀地分布在整个微原纤维上,而不是集中在局部边缘区域。仔细检查可能的配置变化,包括周期结构的节距长度和微原纤维的堆叠模式,证实剪切滞后分析得出的结论适用于更复杂的情况。我们的研究表明,通过设计适当的梯度结构来调节界面载荷是一种可能的策略。
Towards greener wind power: Nanodiamond-treated flax fiber composites outperform standard glass fiber composites in impact fatigue tests
Carsten Hinzmann, Nicolai Frost-Jensen Johansen, Charlotte Bay Hasager, Bodil Holst
doi:10.1016/j.compositesa.2024.108342
迈向绿色风能:纳米金刚石处理亚麻纤维复合材料在冲击疲劳测试中优于标准玻璃纤维复合材料
Wind energy is facing two major problems, recyclability of wind turbine blades, primarily made from fiberglass, and rain erosion on the blade’s leading edges. Here, we show that flax fiber reinforced epoxy composites have less impact fatigue damage than glass fiber (GF) composites made with the same resin. The novel treatment of flax with non-toxic nanodiamonds even boosts its outstanding performance. Nanodiamond-treated flax fiber (FFND) composites exhibit a damage incubation period up to 17 times as long as GF composites and have at least 74% less mass loss. This is connected to lower initial impact pressure, less shock wave reflections and better impact absorption of flax composites. The nanodiamonds act as fiber sizing, strengthening the fibers and their matrix interface. This delays fracturing and results in less erosion, making the biodegradable FFND a promising replacement for GF towards a fabrication of more sustainable and longer lasting wind turbine blades.
风能面临着两个主要问题:主要由玻璃纤维制成的风力涡轮机叶片的可回收性,以及叶片前缘的雨水侵蚀。结果表明,亚麻纤维增强环氧树脂复合材料的冲击疲劳损伤小于相同树脂的玻璃纤维复合材料。用无毒纳米金刚石处理亚麻的新方法甚至提高了亚麻的优异性能。纳米金刚石处理亚麻纤维(FFND)复合材料的损伤潜伏期是GF复合材料的17倍,质量损失至少减少74%。这与亚麻复合材料较低的初始冲击压力、较少的冲击波反射和较好的冲击吸收有关。纳米金刚石起到纤维上浆的作用,增强纤维及其基体界面。这延缓了压裂,减少了侵蚀,使可生物降解的FFND成为GF的一个有希望的替代品,用于制造更可持续、更持久的风力涡轮机叶片。
Thermo-mechanical properties of shape-recoverable structural composites via vacuum-assisted resin transfer molding process and in-situ polymerization of poly (tert-butyl acrylate-co-acrylic acid) copolymer
Jei Gyeong Jeon, Byeong Jun So, Yuseung Choi, Yusu Han, Taehoon Kim, Gilyong Shin, Ju Hwan Lee, Hyeong Jun Kim, Ju Hyeon Kim, Saman Farhangdoust, Fu-Kuo Chang, Minkook Kim, Min Wook Lee, Sungryul Yun, Tae June Kang
doi:10.1016/j.compositesa.2024.108360
通过真空辅助树脂转移模塑工艺和聚丙烯酸叔丁酯-共丙烯酸共聚物原位聚合制备形状可恢复结构复合材料的热力学性能
When selecting a polymer matrix to make shape memory polymer composites (SMPCs), it is crucial to consider high elastic modulus below the switching temperature (Tsw), a significant variation in the modulus above Tsw, and the ability to control Tsw. This research introduces shape-recoverable structural composites fabricated from poly (tert-butyl acrylate-co-acrylic acid) (PtBA-AA), which has a significant modulus variation before and after Tsw. Capillary numbers are assessed to minimize void formation at varying acrylic acid (AA) concentrations, which regulate the copolymer’s polarity and the thermo-mechanical properties. The glass transition temperature of PtBA-AA can be adjusted from 47.4 °C to 91.6 °C. Furthermore, the elastic modulus of SMPC increases from 13 GPa to 20 GPa, whereas the tensile strength increases from 526 MPa to 889 MPa. The maximum recovery strength measured 100.4 MPa at an AA molar ratio of 0.23, accompanied by a fixity of 89.1 % and a recovery ratio of 97.2 %.
在选择聚合物基体来制造形状记忆聚合物复合材料(SMPC)时,关键是要考虑在开关温度(Tsw)以下的高弹性模量、Tsw 以上模量的显著变化以及控制 Tsw 的能力。本研究介绍了由聚(丙烯酸叔丁酯-丙烯酸共聚物)(PtBA-AA)制成的可恢复形状的结构复合材料,该材料在切换温度(Tsw)前后具有显著的模量变化。对毛细管数量进行了评估,以便在丙烯酸(AA)浓度变化时尽量减少空隙的形成,从而调节共聚物的极性和热机械性能。PtBA-AA 的玻璃化转变温度可从 47.4 °C 调整到 91.6 °C。此外,SMPC 的弹性模量从 13 GPa 增加到 20 GPa,拉伸强度从 526 MPa 增加到 889 MPa。在 AA 摩尔比为 0.23 时,测得的最大恢复强度为 100.4 兆帕,固定率为 89.1%,恢复率为 97.2%。
Towards yarn-to-yarn friction behavior in various architectures during the manufacturing of engineering woven fabrics
Yu Wang, Jing Guo, Xuejiao Li, Sascha Krugl, Yanan Jiao, Peng Wang
doi:10.1016/j.compositesa.2024.108363
探讨工程机织物制造过程中不同结构中纱线间的摩擦行为
Friction plays an important role in ensuring the quality of fiber-reinforced composites. Understanding and evaluating friction properties across different fabric architectures and yarn pre-tensions pose significant challenges. In this current research, the influence of fabric architectures and yarn pre-tensions on friction properties during the weaving process were investigated. A novel micro-meso theoretical model based on Peirce’s geometrical model to predict friction properties was developed. The theoretical model shows strong agreement with experimental results, particularly regarding fabric architectures. It can be found that yarn pre-tensions, a critical parameter, increased friction force across all tested architectures, directly impacting yarn friction performance. Additionally, the theoretical model was extended to predict the friction properties of yarns during the manufacturing of 3D fabrics. The findings indicate that fabric architecture significantly influences friction behavior, with the configuration cell depending not only on yarn dimensions but also on preform parameters such as the number of layers, thickness, and binding pattern.
摩擦是保证纤维增强复合材料质量的重要因素。理解和评估不同织物结构和纱线预张力之间的摩擦特性构成了重大挑战。本文研究了织物结构和纱线预张力对织造过程中摩擦性能的影响。在Peirce几何模型的基础上,提出了一种预测摩擦性能的微细观理论模型。理论模型与实验结果非常吻合,特别是在织物结构方面。可以发现,纱线预张力是一个关键参数,它增加了所有测试结构的摩擦力,直接影响纱线的摩擦性能。此外,将理论模型扩展到三维织物制造过程中纱线摩擦性能的预测。研究结果表明,织物结构对摩擦行为有显著影响,其结构单元不仅取决于纱线尺寸,还取决于预成型参数,如层数、厚度和粘合模式。
Elastic surrogate modeling of graphene nanoplatelet-reinforced epoxy using computational homogenization
Ragnar Larsson, Danilo J. Carastan, Matheus M. de Oliveira, Linnea Selegård, Mario Martínez
doi:10.1016/j.compscitech.2024.110761
石墨烯纳米板增强环氧树脂的计算均质化弹性代理模型
2D nanoparticles, such as graphene or graphite nanoplatelets, are used as additives in polymer matrices to improve their stiffness and electrical conductivity. In this paper, a finite element-based model for homogenized macrolevel stiffness is developed to understand the increase in stiffness of the epoxy matrix induced by graphene nanoplatelets. The model uses image segmentation of regular SEM micrographs to account for the morphology of the graphene platelet network. Here, it is essential to include a fluctuation field in computational homogenization to describe microstructural relaxation. Platelets of the microstructure are modeled as embedded membranes, assuming perfect bonding to the polymer. To estimate the stiffness of the membrane, we used molecular dynamics simulations from a related paper on layered graphene platelets. A novel feature is the identified anisotropic and isotropic elastic surrogate models obtained by least-squares fits of homogenized microstructural responses. Surrogate models serve as a basis for the evaluation of the stiffness of the nanocomposites, and these models are validated through the Halpin–Tsai and Mori–Tanaka models According to the experimental investigation, the results show that the samples exhibit an increase in stiffness of up to 10 % to 30 % for GNP contents ranging from 1 to 5 wt. %, respectively, obtained from the morphological properties and the weight fraction of the carbon filler.
二维纳米颗粒,如石墨烯或石墨纳米片,被用作聚合物基质的添加剂,以提高其刚度和导电性。本文建立了一种基于有限元的均匀宏观刚度模型,以理解石墨烯纳米片引起的环氧基刚度增加。该模型使用常规SEM显微照片的图像分割来解释石墨烯血小板网络的形态。在这里,必须在计算均质化中加入涨落场来描述微观结构的弛豫。微观结构的血小板被建模为嵌入膜,假设与聚合物完美结合。为了估计膜的刚度,我们使用了相关论文中关于层状石墨烯薄片的分子动力学模拟。一个新的特点是识别各向异性和各向同性的弹性代理模型得到的最小二乘拟合均质微结构响应。替代模型是评价纳米复合材料刚度的基础,并通过Halpin-Tsai和Mori-Tanaka模型对这些模型进行了验证。根据实验研究,结果表明,从形态性质和碳填料的重量分数中获得的GNP含量分别为1 ~ 5 wt. %,样品的刚度增加了10% ~ 30%。
Insights into the influence of welding energy on the ultrasonic welding of glass fibre-reinforced PPS composites
Zhiwu Xu, Zhongwei Ma, Zhengwei Li, Shu Chen, You Wu, He Zhang, Jiuchun Yan
doi:10.1016/j.compscitech.2024.110767
焊接能量对玻璃纤维增强PPS复合材料超声焊接影响的研究
Investigations on ultrasonic welding of thermoplastic composites always focus on carbon fibre-reinforced thermoplastics so far. This study marks the first attempt at joining glass fibre-reinforced polyphenylene sulphide (GF/PPS) using ultrasonic welding. Attributed to the high observability of the glass fibre-reinforced thermoplastic, new discoveries on bonding formation and mechanism of void defect evolution were acquired. A special pattern of alternating high and low heat input regions was revealed, which was independent of welding energy variations and presented an inherent characteristic of ultrasonic welded GF/PPS joints. Squeeze-out and thermal degradation of matrix induced two primary defect types: larger voids with a size of approximately 100 μm were formed in the matrix between fibre bundles at the joint edge at lower welding energies and were diminished at excessive welding energy; smaller microvoids within 10 μm were formed within the fibre bundles voids at moderate welding energies and were increased in prevalence with higher energy levels. The research identified four distinct fracture modes that are strongly influenced by the welding energy and closely linked to the lap shear strength (LSS) of the joint. The GF/PPS joint achieved a maximum LSS of 22.6 MPa, which is the state-of-the-art welding joints, typically resulting from fracturing in the welded adherend. These findings provide valuable insights for refining the ultrasonic welding process of thermoplastic composites.
目前对热塑性复合材料超声焊接的研究主要集中在碳纤维增强热塑性塑料上。本研究标志着首次尝试使用超声波焊接连接玻璃纤维增强聚苯硫醚(GF/PPS)。由于玻璃纤维增强热塑性塑料具有较高的可观察性,在键合形成和空洞缺陷演化机理等方面有了新的发现。结果表明,超声焊接GF/PPS接头具有一种特殊的高低热输入区交替分布模式,该模式与焊接能量变化无关,是超声焊接GF/PPS接头的固有特征。基体的挤压和热降解导致两种主要缺陷类型:焊接能量较低时,在接头边缘纤维束之间的基体中形成较大的约100 μm的空洞,焊接能量过高时,空洞逐渐减小;在中等焊接能量下,纤维束孔洞内形成了较小的10 μm微孔洞,随着能量水平的提高,微孔洞的数量增加。研究确定了四种不同的断裂模式,它们受焊接能量的强烈影响,并与接头的搭接抗剪强度(LSS)密切相关。GF/PPS接头的最大LSS为22.6 MPa,这是目前最先进的焊接接头,通常是由于焊接接头的断裂造成的。这些发现为改进热塑性复合材料的超声焊接工艺提供了有价值的见解。