今日更新:Composite Structures 1 篇,Composites Part A: Applied Science and Manufacturing 3 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 1 篇
Coupled vibration analysis of bolted variable angle tow plates under combined nonlinear effects
Xiaofeng Liu, Wei Sun, Honghao Liu, Dongxu Du, Hongwei Ma, Hui Li
doi:10.1016/j.compstruct.2023.117847
组合非线性效应下螺栓连接变角拖板的耦合振动分析
To establish a dynamical modal of variable angle tow (VAT) plate accurately, the fiber path and fiber orientation of the VAT plate are described by high-order polynomials. Then, a simplified nonlinear joint model with interface dynamic partitioning is proposed to simulate the interface mechanical behavior of bolted joints. Based on these, a nonlinear semi-analytic dynamic model of the bolted VAT plate is built, which considers both material and joint nonlinearity and can accurately predict nonlinear vibration response. After verifying the proposed modeling method, a special bolted VAT plate is used as the analysis object for free vibration and forced vibration analysis. Firstly, the frequency veering behavior of the VAT plate caused by variations in boundary stiffness, connection stiffness, and fiber orientation is studied. Then, by analyzing the forced vibration response of the bolted VAT plate, it is found that under the combined effect of the modal interaction, material nonlinearity, and joint nonlinearity, the bolted VAT plate exhibited complex but rule-based nonlinear dynamic behavior. More importantly, the research work done in this paper has certain guiding significance for the optimization design of vibration resistance of a bolted VAT thin-walled structure with variable stiffness parameters and joint parameters as design variables.
为了准确建立变角丝束(VAT)板的动力学模态,用高阶多项式描述了变角丝束板的纤维路径和纤维取向。然后,提出了具有界面动态分区的简化非线性连接模型,以模拟螺栓连接的界面力学行为。在此基础上,建立了螺栓连接 VAT 板的非线性半解析动态模型,该模型同时考虑了材料和接头的非线性,可以准确预测非线性振动响应。在验证了所提出的建模方法后,以特殊的螺栓连接 VAT 板为分析对象,进行了自由振动和强迫振动分析。首先,研究了由边界刚度、连接刚度和纤维取向变化引起的 VAT 板频率偏移行为。然后,通过分析螺栓连接 VAT 板的受迫振动响应,发现在模态相互作用、材料非线性和连接非线性的共同作用下,螺栓连接 VAT 板表现出复杂但有章可循的非线性动态行为。更重要的是,本文的研究工作对于以可变刚度参数和连接参数为设计变量的螺栓连接 VAT 薄壁结构的抗振性优化设计具有一定的指导意义。
Micro structural design and macro synthesis of aerogel networks with gradient stiffness properties
Fuhua Xue, Qingyu Peng, Zonglin Liu, Xingchen Guo, Qian Yan, Xu Zhao, Xiaodong He
doi:10.1016/j.compositesa.2023.107978
具有梯度刚度特性的气凝胶网络的微观结构设计和宏观合成
Conductive aerogels have received extensive attention in a variety of application fields such as structural engineering and electrochemistry due to their lightweight, porous and conductive properties. The stiffness of aerogel is a key factor affecting its performance. So compared with conventional single-stiffness aerogels, the preparation of conductive aerogels with gradient stiffness properties is expected to achieve better stiffness matching and greater performance. Here, we develop a theoretical model of the gradient stiffness carbon nanotube (CNT) network and analyze the factors affecting the stiffness of the model from several perspectives, including spatial configuration and intrinsic parameters. Then, according to the guidance of the simulation results, actual CNT aerogels with gradient stiffness properties are successfully synthesized which have an ultra-wide range of stiffness variations. The unique lightweight gradient stiffness conductive aerogels are expected to show outstanding performance in many stiffness-dominated application fields.
导电气凝胶因其轻质、多孔和导电特性,在结构工程和电化学等多个应用领域受到广泛关注。气凝胶的刚度是影响其性能的关键因素。因此,与传统的单一刚度气凝胶相比,制备具有梯度刚度特性的导电气凝胶有望实现更好的刚度匹配和更高的性能。在此,我们建立了梯度刚度碳纳米管(CNT)网络的理论模型,并从空间构型和内在参数等多个角度分析了影响模型刚度的因素。然后,根据模拟结果的指导,成功合成了具有梯度刚度特性的实际碳纳米管气凝胶,其刚度变化范围极广。这种独特的轻质梯度刚度导电气凝胶有望在许多以刚度为主的应用领域展现出卓越的性能。
Investigation of laser-patterned biomimetic microstructures on CFRP and AA5052 surfaces to enhance their single-lap bonding strength
Shih-Feng Tseng, Yu-Sheng Chen, Tang-Wei Gao, Chil-Chyuan Kuo
doi:10.1016/j.compositesa.2023.107980
研究 CFRP 和 AA5052 表面的激光图案生物仿生微结构,以增强其单次粘接强度
This study focused on laser patterning of the biomimetic microstructures of gecko and tree frog patterns on the bonding surface of CFRP and AA5052 to improve their single-lap bonding strength. Laser-patterned biomimetic microstructures produced a rough surface and a superhydrophilic characteristic. A confocal laser microscope, contact angle measurement equipment and Fourier transform infrared spectroscopy were utilized to examine the surface roughness, wettability characteristic, and chemical bond of CFRP and AA5052, respectively. After the 8-week aging test, the lap shear strength of the test samples without pattern and with gecko and tree frog patterns was 2.22 ± 0.82 MPa, 9.26 ± 0.29 MPa, and 8.56 ± 0.15 MPa, respectively, which decreased approximately 75.8%, 10.96% and 13.09% compared to the unaging tests, respectively. The biomimetic microstructures of laser-ablated gecko patterns were helpful in enhancing the bonding strength of heterogeneous materials and in resisting drastic changes in the environment.
本研究的重点是在 CFRP 和 AA5052 的粘合表面上激光刻画壁虎和树蛙图案的仿生物微结构,以提高它们的单层粘合强度。激光图案化的仿生物微结构产生了粗糙的表面和超亲水性特征。利用激光共聚焦显微镜、接触角测量设备和傅立叶变换红外光谱仪分别检测了 CFRP 和 AA5052 的表面粗糙度、润湿特性和化学键。经过 8 周老化试验后,无花纹、有壁虎和树蛙花纹的试样的搭接剪切强度分别为 2.22 ± 0.82 MPa、9.26 ± 0.29 MPa 和 8.56 ± 0.15 MPa,与未老化试验相比,分别下降了约 75.8%、10.96% 和 13.09%。激光照射壁虎图案的仿生微结构有助于提高异质材料的粘接强度和抵抗环境的剧烈变化。
Magnetically assisted construction of Al2O3 platelets dual network and its excellent thermal conductivity in epoxy resin composites
Fanjun Guo, Kangle Xue, Tao You, Zibo Hua, Li Liu, Jun Li, Yudong Huang
doi:10.1016/j.compositesa.2023.107988
磁力辅助构建 Al2O3 小板双网络及其在环氧树脂复合材料中的优异导热性能
Constructing three-dimensional thermally conductive networks in polymer matrix is a key strategy to improve the thermal management performance of electronic packaging materials. However, optimizing the thermal conductivity of the composite while retaining its electrical insulation properties still requires further structural design. Herein, the heat-transferring Al2O3 platelets dual network was constructed by using a simple compression moulding method combined with a magnetic alignment strategy. Al2O3@Fe3O4 was used for the magnetic orientation arrangement in the vertical direction of the laminated Al2O3 framework. And the obtained Al2O3/Al2O3@Fe3O4/Epoxy composites possessed satisfactory thermal conductivity. The thermal conductivity of the composites containing 34.63 vol% filler was as high as 2.30 W/mK (K‖) and 1.83 W/mK (K⊥), which were significantly higher by 945% and 732% compared to epoxy resin. In addition, the introduction of Al2O3@Fe3O4 in the composite promoted isotropic thermal conductivity and provided electromagnetic shielding properties.
在聚合物基体中构建三维导热网络是提高电子封装材料热管理性能的关键策略。然而,在优化复合材料导热性能的同时保留其电气绝缘性能仍需要进一步的结构设计。在此,我们采用简单的压缩成型方法,结合磁性排列策略,构建了传热 Al2O3 小板双网络。Al2O3@Fe3O4 用于层叠 Al2O3 框架垂直方向的磁性取向排列。所获得的 Al2O3/Al2O3@Fe3O4/ 环氧树脂复合材料具有令人满意的导热性。含有 34.63 Vol% 填料的复合材料的导热系数分别高达 2.30 W/mK (K‖)和 1.83 W/mK (K⊥),与环氧树脂相比,分别显著提高了 945% 和 732%。此外,复合材料中 Al2O3@Fe3O4 的引入促进了各向同性导热性,并提供了电磁屏蔽性能。
3D printing of topologically optimized wing spar with continuous carbon fiber reinforced composites
Yiming Huang, Xiaoyong Tian, Wudan Li, Shiji He, Peng Zhao, Handong Hu, Qian Jia, Meng Luo
doi:10.1016/j.compositesb.2023.111166
用连续碳纤维增强复合材料 3D 打印拓扑优化机翼撑杆
The necessity for more efficient manufacturing approaches of high-performance complex fiber reinforced composites parts is increasing. This study develops a framework to design and produce topologically optimized continuous carbon fiber reinforced composites (CCFRCs) with both high manufacturing efficiency and manufacturability, and experimentally validates via material extrusion (MEX) 3D printing technique in a more than 1-m wing spar for the unmanned aerial vehicle (UAV). The load-carrying structure can be topologically optimized by a solid orthotropic material with penalization method and further designed into a continuous fiber trajectory under the consideration of optimal material density, optimal fiber orientation and 3D printing process limitation. Based on this method, the complex topological CCFRCs can be realized by a single-stroke printing path with intact fiber. The feasibility and effectiveness of the proposed framework have been evaluated on the Messerschmitt-Bölkow-Blohm (MBB) beam which reveals obvious higher performance in specific stiffness and peak load compared with commonly used honeycomb structure. As a case study, a topologically optimized UAV wing spar was designed and validated experimentally. Mechanical testing shows that the designed wing spar can survive in operating loads. Furthermore, a proof-of-concept internal wing structure was presented where conventional wing spar and ribs are replaced by CCFRCs 3D printed structures. It exhibits high load-carrying characteristics, is lightweight and simple to fabricate.
高性能复杂纤维增强复合材料部件越来越需要更高效的制造方法。本研究开发了一个框架,用于设计和生产拓扑优化的连续碳纤维增强复合材料(CCFRC),该框架具有较高的制造效率和可制造性,并通过材料挤压(MEX)3D 打印技术在无人机(UAV)超过 1 米的机翼撑杆上进行了实验验证。在考虑最佳材料密度、最佳纤维取向和三维打印工艺限制的情况下,该承载结构可通过带惩罚方法的固体正交材料进行拓扑优化,并进一步设计成连续纤维轨迹。基于这种方法,复杂拓扑结构的 CCFRC 可通过完整纤维的单冲打印路径实现。我们在梅塞施密特-伯尔考-布洛姆(MBB)梁上评估了所提框架的可行性和有效性,结果表明,与常用的蜂窝结构相比,该结构在比刚度和峰值载荷方面具有更高的性能。作为案例研究,我们设计了拓扑优化的无人机翼梁,并进行了实验验证。机械测试表明,所设计的翼撑能够在工作载荷下正常工作。此外,还展示了一种概念验证内部机翼结构,即用 CCFRC 3D 打印结构取代传统的翼尖和翼肋。该结构具有承载能力强、重量轻、制造简单等特点。
Cryogenic damage mechanisms of CFRP laminates based on in-situ X-ray computed tomography characterization
Yuanchen Li, Jinxin Meng, Guohao Niu, Heng Yang, Panding Wang, Hongshuai Lei, Daining Fang
doi:10.1016/j.compscitech.2023.110413
基于原位 X 射线计算机断层扫描表征的 CFRP 层压板低温损伤机理
Carbon fiber reinforced polymer (CFRP) composites possess excellent properties suitable for use in spacecraft liquid fuel tanks. However, the cryogenic reliability of composites remains challenging owing to the variation in mechanical responses under cryogenic environments. So far, most previous studies have focused on the cryogenic properties of composites, and little has been devoted to the cryogenic damage behaviors of laminates. Herein, the cryogenic damage evolution of CFRP laminates was investigated by micro-computed tomography (μCT) characterization and micromechanical analysis for the first time. To this end, in-situ μCT tensile tests for quasi-isotropic CFRP laminates were conducted at temperatures of 293 K, 193 K, and 93 K, and the observed cryogenic damage characteristics were analyzed. A micromechanical computational model was then developed, and the temperature-dependent constitutive model of epoxy resin was utilized to investigate the cryogenic damage evolution process of laminates. The effects of matrix property variation and thermal stresses on the cryogenic damage of laminates were examined, and the cryogenic fracture toughness for transverse cracking was deduced. The characterization results revealed a significantly increased damage volume fraction of laminates from 0.65% to 1.56% at cryogenic temperatures, mainly originating from the increased delamination (from 0.08% to 0.54%) and 90° ply transverse cracks (from 0.48% to 0.87%). The numerical analyses indicated the cryogenic brittle transition of the matrix as the primary factor responsible for the delamination, while the transverse cracks were influenced by matrix properties and thermal stresses. This study provides critical insight into the cryogenic damage behavior of CFRP laminates, essential for cryogenic applications of composites.
碳纤维增强聚合物(CFRP)复合材料具有适用于航天器液体燃料箱的优异性能。然而,由于低温环境下机械响应的变化,复合材料的低温可靠性仍然具有挑战性。迄今为止,以往的研究大多集中在复合材料的低温性能上,而对层压板的低温损伤行为研究较少。本文首次通过微计算机断层扫描(μCT)表征和微机械分析研究了 CFRP 层压板的低温损伤演变。为此,在 293 K、193 K 和 93 K 温度下对准各向同性 CFRP 层压板进行了原位 μCT 拉伸试验,并对观察到的低温损伤特征进行了分析。然后建立了微机械计算模型,并利用环氧树脂的温度依赖性构成模型研究了层压板的低温损伤演变过程。研究了基体性质变化和热应力对层压板低温损伤的影响,并推导出横向开裂的低温断裂韧性。表征结果表明,在低温条件下,层压板的损伤体积分数从 0.65% 显著增加到 1.56%,主要源于分层(从 0.08% 增加到 0.54%)和 90° 层横向裂纹(从 0.48% 增加到 0.87%)的增加。数值分析表明,基体的低温脆性转变是造成分层的主要因素,而横向裂纹则受到基体特性和热应力的影响。这项研究为 CFRP 层压板的低温损伤行为提供了重要见解,对复合材料的低温应用至关重要。