今日更新:Composite Structures 1 篇,Composites Part A: Applied Science and Manufacturing 1 篇,Composites Science and Technology 2 篇
3D winding path modeling method with fiber overlap effect
Shuo Li, Zhuo Meng, Richen Hong, Yize Sun
doi:10.1016/j.compstruct.2024.118488
考虑纤维重叠效应的三维缠绕路径建模方法
The fibers will repeatedly cross and stack on the liner during the continuous winding process, which poses a challenge in creating accurate local and global structure models. To address the issue, a 3D winding path modeling method is proposed to simulate the fiber overlap effect. First, the initial path is offset equidistantly along the direction of width and thickness to construct a 3D fiber model. Then, by calculating the overlap thickness, the overlapped fibers are raised to the corresponding overlap thickness to eliminate interference in the 3D fiber model. Finally, a 3D winding path with the fiber overlap effect is obtained by solving the suspended points before and after the overlapping area to describe the behavior of fibers separating from the liner surface under tension. The proposed method is applied to various winding patterns and liner shapes, and the results show that the established 3D winding path can accurately simulate the fiber overlap effect and correspond with the actual local and global winding structures.
在连续缠绕过程中,纤维会反复交叉和堆叠在内衬上,这对创建准确的局部和全局结构模型提出了挑战。为了解决这一问题,提出了一种三维缠绕路径建模方法来模拟纤维重叠效应。首先,将初始路径沿宽度和厚度方向等距偏移,构建三维纤维模型;然后,通过计算重叠厚度,将重叠的纤维提升到相应的重叠厚度,消除三维纤维模型中的干扰。最后,通过求解重叠区域前后的悬浮点,得到具有纤维重叠效应的三维缠绕路径,以描述纤维在张力作用下与衬垫表面分离的行为。将该方法应用于各种缠绕方式和线材形状,结果表明,所建立的三维缠绕路径能够准确模拟纤维重叠效应,并与实际的局部和全局缠绕结构相对应。
Ultrafast response and highly sensitivity of flexible acoustic sensor based on the controllable hierarchical Nano/Micro-Structure
Fan Chang, Xu Zhu, Zhong Lian, Jiahao Song, Xiao Ouyang, Ning Ma, Xueqiang Liu, Xinyue Zhang
doi:10.1016/j.compositesa.2024.108415
基于可控层次纳米/微结构的柔性声传感器的超快响应和高灵敏度
Flexible and highly sensitive acoustic sensors have become more and more essential for successful military detection. It puts a big barrier for the large-scale production and application. In this work, we have a low-cost and facile approach constructing a hierarchical nano/micro-structure based on the nanosheets of MXene (Ti3C2Tx) and the gold micro-wrinkles on polydimethylsiloxane (PDMS) surface. The period micro-wrinkles can be easily controlled by the thickness of gold layer and the pre-strain on PDMS through the uniaxial stretching method. The formed hierarchical structure can endow the high sensitivity (15 kPa−1 when applied pressure less than 50 Pa), an ultra-fast response time of 15 ms, a minimum detection of 2 Pa, which can achieve the precise acoustic detection of low frequency. Moreover, the flexible sensor also can detect the large pressure about 1000 Pa, and show stable repeatability over 1500 cycles at 400 Pa.
柔性和高灵敏度的声传感器已成为成功的军事探测的必要条件。这对大规模生产和应用造成了很大的障碍。在这项工作中,我们利用MXene (Ti3C2Tx)纳米片和聚二甲基硅氧烷(PDMS)表面的金微皱,构建了一种低成本、简便的层次化纳米/微结构。通过单轴拉伸的方法,可以很容易地通过金层厚度和PDMS上的预应变来控制周期微皱。所形成的层次化结构具有高灵敏度(施加压力小于50 Pa时为15 kPa−1)、超快响应时间为15 ms、最小探测2 Pa,可实现低频的精确声学探测。此外,柔性传感器还可以检测约1000 Pa的大压力,并在400 Pa下表现出超过1500次的稳定重复性。
Simultaneous enhancement of axial/transverse compressive strength of aramid fibers by the construction of branched multi-hydrogen bonding sites
Xueyong Deng, Wen Zhai, Chunlin Fan, Longbo Luo, Xiangyang Liu
doi:10.1016/j.compscitech.2024.110797
支化多氢键位点的构建同时增强芳纶纤维的轴/横向抗压强度
The terrible compressive strength is a prominent issue that restricts the broad application of organic fibers in multi-dimensional stress scenarios. Traditional strategies focus on enhancing the axial compressive performance of fibers, simultaneously improving the axial and transverse compressive properties of fibers still poses significant challenges. Inspired by the octopus's tentacles that can conduct stress in multiple directions, a novel strategy by constructing branched multi-hydrogen bonding sites structure in aramid fiber was conducted to solve the problem. The branched multi-hydrogen bonding sites constructed on nano-silica (SiO2-B) offer excellent dispersibility within the poly(p-phenylene-benzimidazole-terephthalamide) (PBIA) matrix. Composite fibers (PBIA-SiO2-B) co-mixed with SiO2-B and PBIA were prepared using a solution spinning technique. The results of Fourier-transform infrared spectroscopy (FTIR) and dynamic mechanical analysis (DMA) reveal that the introduction of SiO2-B significantly enhances the intermolecular interactions within the composite fibers, and this enhancement mechanism has been elaborately elucidated through molecular simulations. Furthermore, finite element simulations confirmed that the incorporation of branched structure exhibits enhanced stress-bearing capabilities under multi-directional stress and offers outstanding support when subjected to transverse compressive stress compared to linear molecular chains. Hence, compressive property testing revealed that the PBIA-SiO2-B composite fibers achieved axial compressive strengths and transverse compressive strengths of 714.3 MPa and 305.8 MPa, respectively, representing increases of 68.8% and 26.8% over pure PBIA fibers. Moreover, with the enhancement of transverse compressive strength, the Young’s modulus and interfacial shear strength of PBIA-SiO2-B fibers were also increased by 7.1% and 20.9%, respectively.
抗压强度差是制约有机纤维在多维应力环境下广泛应用的突出问题。传统的策略侧重于提高纤维的轴向抗压性能,同时提高纤维的轴向和横向抗压性能仍然存在重大挑战。受章鱼触手可向多个方向传导应力的启发,在芳纶纤维中构建支链多氢键位点结构来解决这一问题。在纳米二氧化硅(SiO2-B)上构建的支链多氢键位点在聚(对苯-苯并咪唑-对苯二甲酸)(PBIA)基体中具有优异的分散性。采用溶液纺丝技术制备了与SiO2-B和PBIA共混的PBIA-SiO2-B复合纤维。傅里叶变换红外光谱(FTIR)和动态力学分析(DMA)结果表明,SiO2-B的引入显著增强了复合纤维内部的分子间相互作用,并通过分子模拟详细阐明了这种增强机理。此外,有限元模拟证实,与线性分子链相比,分支结构的结合在多向应力下表现出更强的应力承受能力,并且在承受横向压应力时提供出色的支撑。因此,抗压性能测试表明,PBIA- sio2 - b复合纤维的轴向抗压强度和横向抗压强度分别为714.3 MPa和305.8 MPa,比纯PBIA纤维提高了68.8%和26.8%。此外,随着横向抗压强度的提高,PBIA-SiO2-B纤维的杨氏模量和界面抗剪强度也分别提高了7.1%和20.9%。
Study on interface toughening mechanism based on modified PBO fiber for CFRP/ plastic honeycomb sandwich structure
Haotian Zheng, Jicai Liang, Yi Li, Ce Liang
doi:10.1016/j.compscitech.2024.110817
基于改性PBO纤维的CFRP/塑料蜂窝夹层结构界面增韧机理研究
CFRP (carbon fiber reinforced composites)/honeycomb sandwich structures are widely used in aerospace, automotive, and high-speed rail industries due to their excellent mechanical properties and lightweight characteristics. This study investigates the impact of three designed toughened interfaces on the three-point bending performance of honeycomb structures. The results show that introducing a multiscale toughened interface made of poly(p-phenylene benzobisoxazole) (PBO) fibers grafted with polydopamine (PDA) and multi-walled carbon nanotubes (CNT) increases the peak load and post-peak load of the sandwich structure by 49.7 % and 51.9 %, respectively, and the absorbed energy by 92.4 %. This toughened interface adjusts the stress relationship between the panel, interface, and honeycomb, altering the deformation process and crack propagation mode of the sandwich structure. The micro-nano fibers form fiber bridging at the interface, changing the crack extension mode between the interfaces, transforming the delamination from a single debonding to the combined action of plate core debonding and honeycomb core buckling. Additionally, experimental results show that PBO fibers treated with PDA and CNT exhibit significantly improved surface roughness, Surface area per unit mass, wettability, and tensile strength, which delay and prevent crack propagation at the interface, effectively reducing panel debonding at the bonded joints.
CFRP(碳纤维增强复合材料)/蜂窝夹层结构以其优异的力学性能和轻量化等特点,广泛应用于航空航天、汽车、高铁等行业。研究了设计的三种增韧界面对蜂窝结构三点弯曲性能的影响。结果表明,引入聚对苯并二苯并异恶唑(PBO)纤维接枝聚多巴胺(PDA)和多壁碳纳米管(CNT)的多尺度增韧界面,使夹层结构的峰后负荷和峰后负荷分别提高了49.7%和51.9%,吸收能量提高了92.4%。这种增韧的界面调整了面板、界面和蜂窝之间的应力关系,改变了夹层结构的变形过程和裂纹扩展模式。微纳纤维在界面处形成纤维桥接,改变了界面间的裂纹扩展方式,使分层由单一的脱粘转变为板芯脱粘和蜂窝芯屈曲的共同作用。此外,实验结果表明,经PDA和CNT处理的PBO纤维表面粗糙度、单位质量表面积、润湿性和抗拉强度显著提高,从而延缓和阻止了界面处的裂纹扩展,有效地减少了粘结接缝处的面板脱粘。