今日更新:Composite Structures 1 篇,Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 1 篇
Dynamic crushing performance of foam-filled periodic hybrid cellular structures
Ting Liu, Changhai Chen, Yuansheng Cheng
doi:10.1016/j.compstruct.2024.117952
泡沫填充周期性混合蜂窝结构的动态挤压性能
To achieve excellent dynamic crushing performance, an attractive foam-filled periodic hybrid cellular (F-PHC) structure containing both hexagonal and re-entrant cells was designed and fabricated. Dynamic crushing experiments for foam-filled PHC structures were carried out using a direct impact Kolsky bar testing system. Reliable numerical simulations using both finite element method and smoothed particle hydrodynamics method were developed to analyze the dynamic crushing responses of F-PHC structures in the full range of deformation processes. Effects of inertia, strain-rate sensitivity, cell number, and impact velocity were evaluated. The results show that the dynamic plateau stresses of periodic hybrid cellular structures can be substantially enhanced by filling foams. The dynamic crushing response of F-PHC structure is very susceptible to impact velocity due to inertia effect. Compared with foam-filled hexagonal honeycomb and foam-filled re-entrant honeycomb structures, F-PHC structures exhibited superior dynamic crushing performances, including smoother and longer dynamic plateau stresses, more uniform deformation distributions, and much more stable deformation processes. Moreover, F-PHC structures exhibited much lower dynamic initial peak stresses at the rear face. This study provides a fascinating design idea and shines light on attractive F-PHC structures with a promising application prospect in the field of impact protection.
为了实现出色的动态破碎性能,我们设计并制造了一种极具吸引力的泡沫填充周期性混合蜂窝(F-PHC)结构,其中既包含六边形蜂窝,也包含重入式蜂窝。使用直接冲击 Kolsky 棒测试系统对泡沫填充 PHC 结构进行了动态破碎实验。采用有限元法和平滑粒子流体力学法进行了可靠的数值模拟,以分析 F-PHC 结构在各种变形过程中的动态挤压响应。对惯性、应变速率敏感性、单元数和冲击速度的影响进行了评估。结果表明,填充泡沫可大幅提高周期性混合蜂窝结构的动态高原应力。由于惯性效应,F-PHC 结构的动态挤压响应非常容易受到冲击速度的影响。与填充泡沫的六边形蜂窝结构和填充泡沫的重入角蜂窝结构相比,F-PHC 结构表现出更优越的动态挤压性能,包括更平滑、更长的动态高原应力,更均匀的变形分布,以及更稳定的变形过程。此外,F-PHC 结构在后端面表现出更低的动态初始峰值应力。这项研究提供了一种令人着迷的设计思路,并揭示了极具吸引力的 F-PHC 结构,在冲击防护领域具有广阔的应用前景。
Predicting the geometric morphology of water jet machining in ultra-thick CFRP laminates based on analytical modeling
Liang Wei, Dong Huiyue, Miao Lei, Xu Xiaokang, Cheng Liang, Guo Yingjie, Ke Yinglin
doi:10.1016/j.compositesa.2024.108055
基于分析建模预测超厚 CFRP 层压板水射流加工的几何形态
The kerf taper and cutting front drag are crucial factors limiting the abrasive waterjet (AWJ) machining of ultra-thick CFRP laminates. Therefore, this study investigated the variation patterns of kerf width and maximum cutting front drag with process parameters and established predictive models. The models accurately predicted kerf entrance width, kerf exit width, and maximum cutting front drag with R-squares of 0.9881, 0.9761, and 0.9791. Moreover, the influence of the key kinematic parameter of complex structure manufacturing - the jet impact angle on the kerf profile was analyzed from a geometric analysis. A numerical regression approach was employed to derive an energy dissipation function for CFRP laminate processing. A semi-analytical mathematical model was established based on energy balance theory. Under arbitrary jet impact angle, the kerf profiles on both sides are predicted with R-square of 0.9455 and 0.9525 respectively, and the cutting front drag profile is predicted with R-square of 0.9078.
切口锥度和切割前阻力是限制加砂水刀(AWJ)加工超厚 CFRP 层压板的关键因素。因此,本研究调查了切口宽度和最大切割前阻力随工艺参数的变化规律,并建立了预测模型。模型准确预测了切口入口宽度、切口出口宽度和最大切削前阻力,R-squares 分别为 0.9881、0.9761 和 0.9791。此外,还从几何分析的角度分析了复杂结构制造的关键运动参数--射流冲击角对切口轮廓的影响。采用数值回归方法得出了 CFRP 层压板加工的能量耗散函数。根据能量平衡理论建立了半解析数学模型。在任意射流冲击角度下,两侧切口轮廓的预测 R 方分别为 0.9455 和 0.9525,切削前阻力轮廓的预测 R 方为 0.9078。
Stability of crystallographic texture and mechanical anisotropy toward Al2O3/YAG eutectic ceramic composite using single crystalline seeds
Yuan Liu, Haijun Su, Xue Tan, Zhonglin Shen, Xiang Li, Hao Jiang, Di Zhao, Yinuo Guo, Zhuo Zhang, Min Guo
doi:10.1016/j.compositesb.2024.111263
使用单晶种子实现 Al2O3/YAG 共晶陶瓷复合材料结晶纹理和机械各向异性的稳定性
During the directional solidification of Al2O3-based eutectic ceramic composites, crystallographic orientation control is a promising method for tailoring the performances of composite parts. However, despite its importance in the fabrication of texture-controlled structural parts, the stable growth of the eutectic crystallographic texture for long distance (growth distance from 30 mm to 120 mm) in ceramic composite system is not widely understood. Herein, the competition and stability of crystallographic texture for Al2O3/YAG eutectic ceramic composite induced by different seeds using the Czochralski (CZ) technique were investigated. When the eutectic composites induced by different single crystalline Al2O3 seeds, coarse Al2O3 particles and uniform eutectic structure appeared alternately below the seeds. While the eutectic ceramic composite induced by YAG seed has a memory effect on the stability of its microstructure and morphology. We demonstrated that the eutectic ceramic composites induced by the〈112¯0〉Al2O3 and 101¯0〉Al2O3 seeds could stably inherit the seed orientation and grow as a single crystallographic texture with a low interfacial strain (<10 %). In particular, the stable evolution of crystallographic texture depended not only on the type of seeds but also on the mutual constraint of eutectic coupling growth. Furthermore, the nano-hardness, elastic modulus, and compressive strength (1600 °C) of the composites induced by different seeds have anisotropic characteristics. However, the bending strength was not sensitive to the change of crystallographic texture. It could maintain excellent high temperature stability, which was approximately 265∼316 MPa from room temperature to 1600 °C. These results promote the development of high-performance Al2O3-based eutectic ceramic composites with anisotropic design using seeding technique to tailor their crystallographic texture.
在基于 Al2O3 的共晶陶瓷复合材料的定向凝固过程中,晶体取向控制是一种很有前途的定制复合材料部件性能的方法。然而,尽管结晶取向控制在制造纹理控制结构件方面具有重要意义,但陶瓷复合材料体系中长距离(生长距离从 30 毫米到 120 毫米)共晶结晶纹理的稳定生长还没有得到广泛的了解。本文采用 Czochralski(CZ)技术研究了不同种子诱导的 Al2O3/YAG 共晶陶瓷复合材料结晶纹理的竞争性和稳定性。当不同单晶 Al2O3 种子诱导共晶复合材料时,种子下方交替出现粗 Al2O3 颗粒和均匀的共晶结构。而 YAG 种子诱导的共晶陶瓷复合材料对其微观结构和形态的稳定性具有记忆效应。我们证明了由〈112¯0〉Al2O3 和〈101¯0〉Al2O3 种子诱导的共晶陶瓷复合材料可以稳定地继承种子的取向,并在较低的界面应变(<10%)下生长为单一的晶体纹理。特别是,晶体纹理的稳定演化不仅取决于种子的类型,还取决于共晶耦合生长的相互制约。此外,不同种子诱导的复合材料的纳米硬度、弹性模量和抗压强度(1600 °C)具有各向异性特征。然而,弯曲强度对结晶纹理的变化并不敏感。它能保持极佳的高温稳定性,从室温到 1600 ℃ 的高温稳定性约为 265 ∼ 316 MPa。这些结果促进了利用播种技术定制结晶纹理的各向异性设计的高性能 Al2O3 基共晶陶瓷复合材料的发展。
Structure-property relationship between lignin structures and properties of 3D-printed lignin composites
Shuyang Zhang, Anqi Ji, Xianzhi Meng, Samarthya Bhagia, Chang Geun Yoo, David P. Harper, Xianhui Zhao, Arthur J. Ragauskas
doi:10.1016/j.compscitech.2024.110487
木质素结构与三维打印木质素复合材料性能之间的结构-性能关系
Lignin is a low-cost and renewable bioresource with a huge annual production promising to prepare sustainable materials. However, the poor interfacial adhesion between many lignin-polymer pairs deteriorates the mechanical performance of the composites, which seriously limits the application of lignin in 3D printing via fused depositional modeling. This work examined lignin-polyamide 12 (PA 12) intermolecular interactions (e.g., hydrogen bonding) to address the interface challenge. To realize this goal, the phenolic hydroxyl content was increased on kraft softwood lignin by a LiBr/HBr demethylation procedure, increasing phenoxy content by 61.7%. Increased hydrogen bonding interactions between modified lignin (Pine-Lig-OH) and PA 12 demonstrated a significantly improved molten dynamic modulus by rheological analysis. Regarding mechanical properties, by adding 20 wt% of Pine-Lig-OH, the tensile strength and Young's modulus reached 46.6 MPa and 1.62 GPa, 30.2% and 33.9% higher than PA 12, respectively. Further morphological analysis proved the interfacial interactions are enhanced by showing the difference in the phase gaps. The dynamic mechanical analysis (DMA) supported the conclusion that Pine-Lig-OH could interact with polymer chains, alternating segmental movements due to the strong interaction. This study presents a method to enhance lignin composite properties by promoting interactions with the polymer matrix through modified functional groups, guiding future lignin composite research.
木质素是一种低成本、可再生的生物资源,年产量巨大,有望制备可持续材料。然而,许多木质素-聚合物对之间的界面粘附性较差,会降低复合材料的机械性能,这严重限制了木质素通过熔融沉积模型在三维打印中的应用。这项工作研究了木质素-聚酰胺 12(PA 12)的分子间相互作用(如氢键),以解决界面难题。为实现这一目标,采用 LiBr/HBr 脱甲基工艺增加了牛皮纸软木木质素的酚羟基含量,使苯氧基含量增加了 61.7%。通过流变学分析,改性木质素(Pine-Lig-OH)和 PA 12 之间氢键相互作用的增加显著提高了熔融动态模量。在机械性能方面,添加 20 wt% 的松脂-木质素-OH 后,拉伸强度和杨氏模量分别达到 46.6 MPa 和 1.62 GPa,比 PA 12 分别高出 30.2% 和 33.9%。进一步的形态分析表明,相隙的差异证明了界面相互作用的增强。动态机械分析(DMA)证实了松-lig-OH 可与聚合物链相互作用,由于相互作用强烈,聚合物链段会交替运动。本研究提出了一种通过改性官能团促进与聚合物基体相互作用来增强木质素复合材料性能的方法,为未来的木质素复合材料研究提供了指导。