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【新文速递】2024年7月19日复合材料SCI期刊最新文章

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今日更新:Composite Structures 3 篇,Composites Part A: Applied Science and Manufacturing 3 篇,Composites Science and Technology 2 篇

Composite Structures

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。


Composites Part A: Applied Science and Manufacturing

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。


Composites Science and Technology

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。



来源:复合材料力学仿真Composites FEM
ACTMechanicalAdditive疲劳断裂复合材料UG风能UM焊接理论化机材料分子动力学控制试验
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【新文速递】2024年7月22日复合材料SCI期刊最新文章

今日更新:Composite Structures 6 篇,Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 4 篇Composite StructuresThermal buckling of variable stiffness composite laminates using high order plate finite elementsF. Bracaglia, R. Masia, A. Pagani, E. Zappino, E. Carreradoi:10.1016/j.compstruct.2024.118393用高阶板有限元分析变刚度复合材料层合板的热屈曲This paper proposes a study on the thermal buckling of Variable Angle Tow (VAT) composite plates using high-order theories. Here, the governing equations are derived via the principle of virtual work. Under the assumption of linear pre-buckling, the stability problem is reduced to a linear eigenvalue analysis considering proportional geometric stiffness. In contrast, a constant thermal load is assumed to be known along the plate thickness, and the uncoupled thermo-mechanical formulation is used, where the thermal effects are described as external loads. The plate is discretized using the Finite Element Method (FEM) and high-order theories are developed using the Carrera Unified Formulation (CUF). Using the CUF, the equations are expressed as an invariant of the plate theory approximation order. Therefore, Equivalent Single Layer (ESL) and Layer-Wise (LW) models can be easily implemented. Several geometries and lamination cases are considered for verification purposes, including different side-to-thickness ratios and fiber orientations, which result in various anisotropy effects. In addition, the effect of changing constraints and materials is evaluated. Particular attention is paid to the effect of the structural theory approximation on the evaluation of the thermal buckling load. It is shown that the correct evaluation is highly dependent on the edge-to-thickness ratio and on the anisotropy given by both the fiber orientation and the material properties. As a final remark, sensitivity analysis and best fibre angle solutions are discussed to highlight the importance of the LW modelling approach.本文采用高阶理论对变角Tow复合材料板的热屈曲进行了研究。本文利用虚功原理推导了控制方程。线性的假设下前挠曲,稳定性问题是减少到一个线性特征值分析考虑几何刚度成比例。相反,假设沿板厚已知恒定的热负荷,并使用不耦合的热-机械公式,其中热效应被描述为外部负荷。采用有限元法对板进行离散化,采用Carrera统一公式建立了高阶理论。利用CUF,将方程表示为板理论近似阶的不变量。因此,等效单层(ESL)和分层(LW)模型可以很容易地实现。为了验证目的,考虑了几种几何形状和层压情况,包括不同的边厚比和纤维取向,这些都会导致不同的各向异性效应。此外,还评估了约束条件和材料变化的影响。特别注意了结构理论近似对热屈曲载荷评估的影响。结果表明,正确的评价高度依赖于边厚比和纤维取向和材料性能所给出的各向异性。最后,讨论了灵敏度分析和最佳纤维角解,以突出LW建模方法的重要性。Topological design of soft substrate acoustic metamaterial for mechanical tuning of sound propagationYan Li, Xiaopeng Zhang, Qiming Tian, Yangjun Luodoi:10.1016/j.compstruct.2024.118399用于声音传播机械调谐的软基声学超材料拓扑设计The design of tunable acoustic waves is crucial in phononic crystals (PnCs), as acoustic waves exhibit continuous variation across diverse frequency ranges in practical applications. While there have been research efforts on tunable PnCs, existing design strategies predominantly rely on predetermined topology and scatterer shapes based on empirical experience. This reliance poses challenges in ensuring customized and reversible tuning of the bandgap. In this work, we present a customized tunable PnC design model and solution strategy based on soft substrates, which enables reversible tuning of a specific frequency/order bandgap. The designed structure consists of a soft substrate and crystalline columns dispersed in the soft substrate and air. The relative positions of the scatterers in the air are changed by stretching the substrate, thereby realizing the modulation of sound propagation. Since soft materials have both material nonlinearities and complex geometrical variations that are difficult to obtain design sensitivity information, the material-field series expansion topology optimization approach is employed to achieve custom tunable design of the bandgap. The paper presents simulation-based analyses and experimental verification of the customized bandgap opening and closing. The results demonstrate a close alignment between theoretical predictions of propagation curves and experimental findings. This concurrence serves as evidence that the soft-substrate PnC, derived through topology optimization, effectively facilitates the adjustment of bandgaps of arbitrary orders and enables switching between various acoustic functions.可调谐声波的设计在声子晶体(pnc)中是至关重要的,因为声波在实际应用中在不同的频率范围内表现出连续的变化。虽然对可调谐pnc进行了研究,但现有的设计策略主要依赖于基于经验经验的预定拓扑和散射体形状。这种依赖在确保定制和可逆调谐带隙方面提出了挑战。在这项工作中,我们提出了一种基于软基板的定制可调谐PnC设计模型和解决策略,它可以对特定频率/阶带隙进行可逆调谐。所设计的结构由软基板和分散在软基板和空气中的结晶柱组成。通过拉伸基片来改变散射体在空气中的相对位置,从而实现声音传播的调制。针对软质材料具有材料非线性和复杂几何变化难以获得设计灵敏度信息的特点,采用材料场串联展开拓扑优化方法实现带隙的自定义可调设计。本文对自定义的带隙开闭进行了仿真分析和实验验证。结果表明,理论预测的传播曲线与实验结果非常吻合。这种一致性证明,通过拓扑优化得到的软基板PnC有效地促进了任意阶带隙的调整,并实现了各种声学功能之间的切换。Theoretical study on the bond performance of CFRP-to-steel single-lap shear tests with multiple debonding defectsHugo C. Biscaia, Pedro Coelho, Fábio Conde, Tommaso D’Antinodoi:10.1016/j.compstruct.2024.118406含多剥离缺陷的cfrp -钢单搭接剪切试验粘结性能的理论研究The amount of research on the external bonding of Carbon Fiber Reinforced Polymers (CFRP) to degraded structures has increased recently. The adhesive is the weakest element of the joint and the bonding of the adherends is critical for the efficiency of the joint. Therefore, the influence of multiple debonding defects on CFRP-to-steel joints has still not been correctly quantified nor fully understood. For this reason, the current work proposes a new numerical strategy that allows for studying the influence of multiple debonding defects when a brittle and ductile adhesive is used. A new nonlinear bond-slip relationship is used and four different ratios between the debonded and the bonded area (η) are assumed: 0%, 25%, 50%, and 75%. The proposed model is based on the Finite Difference Method (FDM) and validation is carried out with a commercial Finite Element Method (FEM) package. The load-slip curves allowed for observing that the proposed FDM and the FEM are consistent and both revealed degradation of the load capacity of the joints with the increase of η. Moreover, by adopting a displacement control at the CFRP-free end, a snap-through and snap-back phenomenon are observed in the specimens with a localized debonding defect.近年来,对碳纤维增强聚合物(CFRP)与降解结构外键合的研究越来越多。胶粘剂是接头最薄弱的环节,胶粘剂的粘结对接头的工作效率至关重要。因此,多重脱粘缺陷对cfrp -钢连接的影响还没有得到正确的量化和充分的认识。因此,目前的工作提出了一种新的数值策略,允许研究脆性和延性粘合剂使用时多重脱粘缺陷的影响。采用一种新的非线性粘结-滑移关系,并假设脱粘与粘结面积(η)的比值为0%、25%、50%和75%。所提出的模型基于有限差分法(FDM),并使用商业有限元方法(FEM)软件包进行了验证。从载荷-滑移曲线可以看出,所提出的FDM和FEM是一致的,都显示了节点的承载能力随着η的增加而退化。此外,通过在无cfrp端进行位移控制,在具有局部脱粘缺陷的试件中观察到弹穿和弹回现象。Comparative study on the impact behaviors of CFWST columns reinforced with steel spiral and tubeXia Yang, Jiu-Yuan Wang, Yu Chen, Geng-chen Wudoi:10.1016/j.compstruct.2024.118408钢管与螺旋钢加固CFWST柱冲击性能对比研究To obtain superior corrosion resistance and impact resistance, as well as good economic benefits, two new types of composite structure called as steel tube internally-reinforced concrete-filled weathering steel tube (STRCFWST) and steel spiral internally-reinforced concrete-filled weathering steel (SSRCFWST) columns are proposed and compared in terms of their impact resistance in this paper. Eleven impact tests were conducted and three parameters comprising steel spiral diameter, wall thicknesses of outer and inner steel tube were considered to evaluate their influences on the lateral impact behaviors. Results show the presence of inner steel tube and reinforcement cage significantly enhances the impact resistance while slightly decreases the energy absorption capacity. Increasing inner steel tube wall thickness helps to improve the impact resistance, however the contribution is not so good as that produced by increasing the outer steel tube wall thickness, whilst varying steel spiral diameter almost has no impact. Numerical models were developed by ABAQUS/Explicit and verified via the test, based on which the full-range behaviors of STRCFWST, SSRCFWST and unreinforced concrete-filled weathering steel tube (CFWST) columns under impact loading were compared and discussed. It is demonstrated that steel tube and reinforcement cage provide little confinement on concrete infill under impact. With the same internal steel ratio, inner steel tube makes a greater contribution to sectional bending moment resistance and energy absorption as compared to the reinforcement cage.为了获得优异的耐腐蚀和抗冲击性能以及良好的经济效益,本文提出了钢管内筋混凝土填充耐候钢(STRCFWST)和钢螺旋内筋混凝土填充耐候钢(SSRCFWST)两种新型组合结构,并对其抗冲击性能进行了比较。进行了11次冲击试验,考虑了钢螺旋直径、外、内钢管壁厚3个参数对横向冲击行为的影响。结果表明,内钢管和钢筋笼的存在显著提高了结构的抗冲击能力,但对结构的吸能能力略有降低。增加内管壁厚度有助于提高抗冲击能力,但贡献不如增加外管壁厚度,而改变钢螺旋直径几乎没有影响。采用ABAQUS/Explicit软件建立数值模型并进行试验验证,在此基础上对STRCFWST、SSRCFWST和无筋耐候钢钢管混凝土柱在冲击荷载作用下的全工况性能进行了比较和讨论。结果表明,钢管和钢筋笼对混凝土充填体在冲击作用下的约束作用较小。在相同的内钢比下,内钢管对截面抗弯矩和吸能的贡献大于钢筋笼。Influence of rate effects on delamination: From Crack Leap Shear tests to low-velocity impactsMaxime Pouliquen, Olivier Allix, Roland Ortiz, Juan Pedro Berro Ramirezdoi:10.1016/j.compstruct.2024.118409速率效应对分层的影响:从裂纹跳跃剪切试验到低速冲击This paper is devoted to the study of different aspects of rate effects in the case of delamination. Two rate dependent cohesive zone models are compared for which the shear rate dependency is identified using Crack Leap Shear experiments. For both models, the key factor appears to be the evolution of the critical energy release rate as function of the crack opening. Moreover, if for very low velocity (1 m/s) rate effects can be neglected, it is not the case for quite low velocity (10 m/s). In the case of a 16 plies quasi-isotropic plate for the size and the shape of the delamination are significantly influenced by the rate effects.本文致力于研究分层情况下速率效应的不同方面。比较了两种速率相关的黏聚带模型,并利用裂缝跃进剪切实验识别出剪切速率相关。对于这两种模型,关键因素似乎是临界能量释放率随裂纹开度的变化。此外,如果对于非常低的速度(1m /s)速率效应可以忽略不计,那么对于非常低的速度(10m /s)就不是这样了。在16层准各向同性板的情况下,分层的大小和形状受到速率效应的显著影响。An explicit finite element discrete crack analysis of open hole tension failure in compositesK. Tian, J. Zhi, V.B.C. Tan, T.E. Taydoi:10.1016/j.compstruct.2024.118411复合材料开孔拉伸破坏的显式有限元离散裂纹分析Developing efficient, robust methods for predicting the progressive failure of carbon fiber composites under tension is essential for optimal design, balancing weight reduction, damage tolerance, and service life. Implicit finite element (FE) methods struggle with the complex interplay of failure mechanisms, leading to a heavy reliance on costly, time-consuming experimental testing. This study introduces a novel explicit algorithm designed for laminate-level mesh models, capable of simulating cohesive cracks without predefined paths. Utilizing an explicit finite element software approach, our method effectively addresses convergence issues associated with the non-linear and unstable nature of composite failures during quasi-static loading. Contrasting with implicit FE method, this mesh-independent approach is both practical and numerically robust. The algorithm’s performance, tested on carbon-fiber reinforced composites with varying ply configurations [45_2 /-45_2]s, [45n/90n/-45n/0n]s and [45/90/-45/0]ns (n=1/2/4/8), demonstrates improved simulation accuracy and efficiency over implicit FE methods, aligning well with prior experimental and simulation data. This advancement offers a promising solution for accurately simulating and understanding the complex failure behavior of these composites.开发高效、可靠的方法来预测碳纤维复合材料在拉力作用下的渐进失效,对于优化设计、平衡减重、损伤容限和使用寿命至关重要。隐式有限元 (FE) 方法难以应对复杂的失效机制相互作用,导致严重依赖昂贵、耗时的实验测试。本研究介绍了一种专为层状网格模型设计的新型显式算法,能够模拟无预定路径的内聚裂纹。利用显式有限元软件方法,我们的方法能有效解决与准静态加载期间复合材料失效的非线性和不稳定性相关的收敛问题。与隐式有限元方法相比,这种与网格无关的方法既实用又具有数值稳定性。该算法在不同层配置 [45_2/-45_2]s、[45n/90n/-45n/0n]s 和 [45/90/-45/0]ns(n=1/2/4/8)的碳纤维增强复合材料上进行了性能测试,结果表明,与隐式 FE 方法相比,该算法提高了模拟精度和效率,与之前的实验和模拟数据非常吻合。这一进步为准确模拟和理解这些复合材料的复杂失效行为提供了一种有前途的解决方案。Composites Part A: Applied Science and ManufacturingA new modified direct method for determining the mode I delamination traction-separation lawA.B. de Moraisdoi:10.1016/j.compositesa.2024.108365一种新的改进的直接法确定I型分层牵引分离规律A new equation was developed for the crack-tip separation in the double cantilever beam (DCB) specimen, which has been standardised for mode I delamination of composites. The very simple closed-form equation is based on a pseudo-elastic beam model and on the effective crack concept. Moreover, it only requires the common load–displacement data up to crack initiation and easy to obtain elastic moduli. Strain-energy release rate versus crack-tip separation curves can then be differentiated for obtaining the tractions, as in the classical direct method. Numerical results for piecewise linear traction-separation laws (TSL) showed good accuracy of strain-energy release rate versus crack-tip separation curves predicted. Application to two carbon/epoxy materials gave very promising TSL results, including cohesive strengths similar to transverse tensile strengths and post-peak steep traction decreases.建立了双悬臂梁(DCB)试样裂纹尖端分离的新方程,并对该方程进行了标准化处理。非常简单的封闭形式方程是基于伪弹性梁模型和有效裂缝的概念。该方法只需要裂纹起裂前的常用荷载-位移数据,且弹性模量易于获得。然后,与经典的直接法一样,可以区分应变-能量释放率与裂纹尖端分离曲线,以获得牵引力。分段线性牵引分离律(TSL)的数值结果表明,所预测的应变能释放率与裂纹尖端分离曲线具有较好的准确性。应用于两种碳/环氧树脂材料的TSL结果非常有希望,包括与横向拉伸强度相似的内聚强度和峰后陡峭牵引力下降。Composites Part B: EngineeringDesign optimization of advanced tow-steered composites with manufacturing constraintsChuan Luo, Federico Ferrari, James K. Guestdoi:10.1016/j.compositesb.2024.111739具有制造约束的先进牵引复合材料的设计优化Tow steering technologies, such as automated fiber placement, enable the fabrication of composite laminates with curvilinear fiber, tow, or tape paths. Designers may therefore tailor tow orientations locally according to the expected local stress state within a structure, such that strong and stiff orientations of the tow are (for example) optimized to provide maximal mechanical benefit. Tow path optimization can be an effective tool in automating this design process, yet has a tendency to create complex designs that may be challenging to manufacture. In the context of tow steering, these complexities can manifest in defects such as tow wrinkling, gaps, overlaps. In this work, we implement manufacturing constraints within the tow path optimization formulation to restrict the minimum tow turning radius and the maximum density of gaps between and overlaps of tows. This is achieved by bounding the local value of the curl and divergence of the vector field associated with the tow orientations. The resulting local constraints are effectively enforced in the optimization framework through the Augmented Lagrangian method. The resulting optimization methodology is demonstrated by designing 2D and 3D structures with optimized tow orientation paths that maximize stiffness (minimize compliance) considering various levels of manufacturing restrictions. The optimized tow paths are shown to be structurally efficient and to respect imposed manufacturing constraints. As expected, the more geometrical complexity that can be achieved by the feedstock tow and placement technology, the higher the stiffness of the resulting optimized design.拖曳导向技术,如自动纤维放置,可以制造具有曲线纤维、拖曳或胶带路径的复合材料层压板。因此,设计人员可以根据结构中预期的局部应力状态在局部定制拖缆方向,例如,拖缆的强和硬方向被优化以提供最大的机械效益。拖径优化是实现设计过程自动化的一种有效工具,但它往往会产生复杂的设计,这可能对制造构成挑战。在拖曳转向的情况下,这些复杂性可以表现在缺陷,如拖曳起皱,缝隙,重叠。在这项工作中,我们在牵引路径优化公式中实施制造约束,以限制最小牵引转弯半径和最大牵引间隙和重叠密度。这是通过约束与两个方向相关的向量场的旋度和散度的局部值来实现的。通过增广拉格朗日方法在优化框架中有效地实现了局部约束。通过设计具有优化的两种方向路径的2D和3D结构,从而在考虑各种制造限制的情况下最大化刚度(最小化顺应性),从而证明了所得到的优化方法。优化后的两条路径在结构上是有效的,并且尊重强加的制造约束。正如预期的那样,原料束和放置技术可以实现的几何复杂性越高,优化设计的刚度就越高。Composites Science and TechnologyCharacterization on fibre kinking fracture of laminated composites under combined compression and shear at high loading rateRui He, Longfei Cheng, Yidi Gao, Hao Cui, Yulong Li, Jianhu Liudoi:10.1016/j.compscitech.2024.110770 高加载速率下压剪复合材料纤维扭结断裂特性研究This paper presented a novel method to characterize the fracture toughness and cohesive law of laminated composites under combined compression and shear at high loading rate. Compact compression specimens with off-axis fibres which introduce the in-plane shear stresses were conducted on the uniaxial bidirectional electromagnetic Hopkinson bar system and the displacement field and strain field were recorded by the high-speed camera for the digital image correlation analysis and J-integral calculation. The results reveal that the in-plane shear stresses bring the increase of fracture toughness at crack initiation and propagation and advance the damage initiation of the specimens. The fracture surfaces indicate that the shear stresses cause the fibre bundles' shear failure during the formation of the kink band, accompanied by more energy dissipation with the increase of off-axis angle.提出了一种表征高加载速率下压剪复合层合材料断裂韧性和粘聚规律的新方法。在单轴双向电磁霍普金森杆体系上进行了带离轴纤维且引入面内剪应力的致密压缩实验,利用高速摄像机记录了位移场和应变场,进行了数字图像相关分析和j积分计算。结果表明:面内剪应力增加了裂纹萌生和扩展时的断裂韧性,促进了试样的损伤萌生;断裂面表明,在扭结带形成过程中,剪切应力导致纤维束发生剪切破坏,随离轴角的增大,能量耗散增大。Investigation on Thermal Conductivities of Plain-woven Carbon/Phenolic and Silica/Phenolic Composites at High Temperature: Theoretical Prediction and ExperimentYifan Wang, Qiuyu Wang, Shuangyu Lv, Bowen Zuo, Lei Chen, Taofeng Cao, Chen Chen, Wen-Quan Taodoi:10.1016/j.compscitech.2024.110771 炭/酚醛和硅/酚醛复合材料高温热导率研究:理论预测与实验Phenolic resin-based ablation materials have found widespread applications in the aerospace industry. The prediction of their thermal conductivity is of paramount importance for the optimization and evaluation for thermal protection systems. However, there is rarely reported thermal conductivity performance of phenolic composites during ablation processes. Therefore, this investigation theoretically predicts the dynamic response of thermal conductivity at high temperatures for plain-woven carbon/phenolic and high silica/phenolic composites. By combining the progressive cubic ablation model with existing composite material property formulas, a multiscale prediction model for effective thermal conductivity is developed. The thermal performance of the resin matrix, reinforcing fibers, yarns, and overall fabric composites is calculated. Additionally, mesoscale representative volume elements are implemented to investigate the overall heat transfer characteristics of carbon/phenolic and high-silica/phenolic composites, including temperature and heat flux distributions. Moreover, both composites thermal conductivities are measured in the range from 298 K to 473 K. The proposed prediction model demonstrates good reliability, with average deviations of 3.76% and 7.36% compared to finite element analysis results and experimental data, respectively.酚醛树脂基烧蚀材料在航空航天工业中有着广泛的应用。其导热系数的预测对于热防护系统的优化和评价具有至关重要的意义。然而,在烧蚀过程中,酚醛复合材料的导热性能却鲜有报道。因此,本研究从理论上预测了普通编织碳/酚醛和高硅/酚醛复合材料在高温下导热系数的动态响应。将渐进立方烧蚀模型与现有的复合材料性能公式相结合,建立了复合材料有效导热系数的多尺度预测模型。计算了树脂基体、增强纤维、纱线和整体织物复合材料的热性能。此外,采用中尺度代表性体积元来研究碳/酚醛和高硅/酚醛复合材料的整体传热特性,包括温度和热流密度分布。此外,两种复合材料的热导率在298 ~ 473 K范围内进行了测量。该预测模型具有良好的可靠性,与有限元分析结果和实验数据相比,平均偏差分别为3.76%和7.36%。Fully 3D printed functional PDMS composites with designable structures and performancesYi An, Wenhao Wang, Renyi Cheng, Chenglin Li, Jiaming Liu, Hong Xu, Xiaoli Wang, Daming Wu, Jingyao Sundoi:10.1016/j.compscitech.2024.110773 全3D打印功能PDMS复合材料具有可设计的结构和性能Three-dimensional (3D) printing, as a layer-to-layer additive manufacturing technology, has received widespread attention for excellent designability. However, as for direct ink writing (DIW), current printing level is difficult to achieve high-precision printing of thermoset composites of different compositions. Therefore, fully 3D printing based on thermoset composites with high designability is proposed. The intralayer and interlayer of structure and materials prepared by this method are designable, and layer thicknesses as well as inter-layer patterns are adjustable. In this work, alumina (Al2O3) and short carbon fiber (SCF) are used as thermally conductive fillers, polydimethylsiloxane (PDMS) is conducted as thermoset matrix. Benefit from the high designability of our method, a series of Al2O3/SCF/Al2O3 (ASA) and SCF/Al2O3/SCF (SAS) composite samples with sandwich structures are fabricated and compared. The different materials and structural designs of these composite samples give them completely different properties in terms of thermal, electromagnetic shielding, and mechanical properties, making it possible to create customized designs for different scenarios. Taking thermal management materials (TMMs) as an example, we use this method to prepare ASA and SAS composites with sandwich structure, thermal conductivity of A40S30A40 and S30A40S30 reached 1.00 W/(m·K) and 1.55 W/(m·K) respectively. In all, customized and multifunctional applications make PDMS composites have a widespread prospect.三维打印作为一种层对层增材制造技术,因其优异的可设计性而受到广泛关注。然而,对于直墨书写(DIW),目前的印刷水平很难实现不同成分热固性复合材料的高精度印刷。因此,提出了基于高可设计性热固性复合材料的全3D打印技术。用该方法制备的结构和材料的层内和层间是可设计的,层厚度和层间图案是可调节的。本文采用氧化铝(Al2O3)和短碳纤维(SCF)作为导热填料,聚二甲基硅氧烷(PDMS)作为热固性基体。利用该方法的高可设计性,制备了一系列具有夹层结构的Al2O3/SCF/Al2O3 (ASA)和SCF/Al2O3/SCF (SAS)复合样品并进行了比较。这些复合材料样品的不同材料和结构设计使其在热、电磁屏蔽和机械性能方面具有完全不同的性能,从而可以针对不同的场景创建定制设计。以热管理材料(TMMs)为例,利用该方法制备了具有夹层结构的ASA和SAS复合材料,A40S30A40和S30A40S30的导热系数分别达到1.00 W/(m·K)和1.55 W/(m·K)。总之,定制化和多功能的应用使得PDMS复合材料具有广泛的应用前景。Microscopic damage behavior in CFRP cross-ply laminates at cryogenic temperatureKazuyoshi FUJISHIRO, Toshio OGASAWARA, Koki MIZUTANI, Hisashi KUMAZAWA, Takahira AOKIdoi:10.1016/j.compscitech.2024.110774 低温下CFRP交叉层合板的微观损伤行为For the practical use of cryogenic propellant tanks made of CFRP laminates, experimental elucidation of the laminates’ microstructural damage propagation behavior at cryogenic temperatures is important. This paper presents a newly developed tensile test rig that enables in-situ observation of microscopic damage using an optical microscope at cryogenic temperatures using a Gifford–McMahon refrigerator. In-situ observations of microscopic damage under uniaxial tensile loading were done at room temperature (290 K, 17 °C) and at 30 K (-243 °C) on cross-ply thin-layer CFRP specimens of three kinds with different 90° layer thicknesses. The results demonstrated that the crack propagation behavior is independent of temperature, that the matrix crack density is higher, and that the onset of matrix crack initiation strain is lower at 30 K than at 290 K. Furthermore, the thermal strain within 90° layer at 30 K and 290 K was estimated using finite element analyses (FEA). The FEA results suggest that the decrease in onset strain of matrix crack initiation at 30 K is mainly attributed to the increase in the thermal strains within the 90° layer.为了实际应用碳纤维复合材料制成的低温推进剂储罐,对复合材料在低温下的微结构损伤扩展行为进行实验研究具有重要意义。本文介绍了一种新开发的拉伸试验台,该试验台使用Gifford-McMahon冰箱在低温下使用光学显微镜对微观损伤进行原位观察。在室温(290 K, 17°C)和30 K(-243°C)条件下,对三种不同90°层厚的交叉铺层CFRP薄层试样进行了单轴拉伸加载下的微观损伤现场观察。结果表明:裂纹扩展行为与温度无关,基体裂纹密度较高,30k时基体裂纹起裂应变小于290k;此外,利用有限元分析(FEA)估算了30 K和290 K时90°层内的热应变。有限元分析结果表明,30k时基体裂纹起裂应变的减小主要是由于90°层内热应变的增大。来源:复合材料力学仿真Composites FEM

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