【新文速递】2024年6月29日复合材料SCI期刊最新文章

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今日更新：Composite Structures 1 篇，Composites Part B: Engineering 2 篇，Composites Science and Technology 1 篇

Composite Structures

Flexible, lightweight, tunable robotic arms enabled by X-tensegrity inspired structures

Xiao-Hui Yue, Xu Yin, Zi-Yan Sun, Long-Yue Liu, Yantao Wang, Guang-Kui Xu, Changyong Cao, Li-Yuan Zhang

doi:10.1016/j.compstruct.2024.118331

受 X-tensegrity 结构启发的灵活、轻质、可调机械臂

Robotic arms have remarkable applications in diverse fields such as medical rehabilitation, disaster relief, and space exploration. Enhancing their rigidity, load-bearing capacity, and motion simplicity is key to broadening their usage. Utilizing the admirable flexibility and strength of tensegrity structures, made of rigid bars and elastic strings, we introduce a new type of flexible robotic arm. This arm is constructed using a sequence of two-dimensional X-tensegrity inspired modules. Each module comprises two sets of triangular bars linked by three strings, enhancing the arm’s ability to deform and resist impact forces. The joints between modules are stiff, allowing for angular adjustments to create three-dimensional configurations with adjustable stiffness and curvature. Through theoretical analysis, simulations, and experiments, we have shown that this tensegrity-based robotic arm exhibits superior stability, flexibility, and scalability.

机械臂在医疗康复、救灾和太空探索等多个领域都有出色的应用。提高机械臂的刚度、承重能力和运动简易性是扩大其应用范围的关键。利用由刚性杆和弹性弦组成的张拉整体结构令人钦佩的柔韧性和强度，我们推出了一种新型柔性机械臂。这种机械臂由一系列二维 X-张拉整体模块构成。每个模块由两组三角形杆组成，并由三根绳索连接，从而增强了机械臂的变形和抗冲击能力。模块之间的连接处具有一定的硬度，可以进行角度调整，从而形成具有可调硬度和曲率的三维结构。通过理论分析、模拟和实验，我们证明了这种基于张力整体的机械臂具有卓越的稳定性、灵活性和可扩展性。

Composites Part B: Engineering

Unveiling the microscopic compression failure behavior of mesophase-pitch-based carbon fibers for improving the compressive strength of their polymer composites

Ningyuan Zhang, Dong Huang, Huafeng Quan, Chong Ye, Chaoyi Peng, Lei Tao, Shipeng Zhu, Zhen Fan, Kui shi, Feng Qian, Jinshui Liu

doi:10.1016/j.compositesb.2024.111658

揭示介相沥青基碳纤维的微观压缩失效行为，提高其聚合物复合材料的抗压强度

Mesophase-pitch-based carbon fiber (MPCF) reinforced polymer (MPCFRP) composites show great potential for aerospace applications due to their excellent thermal conductivity and dimensional stability. However, the low compressive strength severely limits their application in high load-bearing areas. To address this issue, MPCF-A with a split-radial structure and MPCF-B with a skin-core structure were meticulously prepared by fiber structure regulation. The compression failure behavior of MPCFs at the monofilament and the microregion levels was investigated using the tensile recoil method and in-situ micropillar compression technique. MPCF-A exhibits the failure mode of petal-like lamellar separation due to axial crack penetrating along the (002) crystal plane of graphite layers, with the compressive strength of the core region (391 MPa) being higher than that of the skin region (360 MPa). Conversely, MPCF-B demonstrates a large transverse fracture in the skin region during damage, along with uniform microcracks in the core region. Notably, the compressive strength of the core region (547 MPa) significantly exceeds that of the skin region (456 MPa). Furthermore, the compressive strength of MPCF-B monofilaments (583 MPa) is higher than that of MPCF-A (462 MPa), attributed to factors such as the smaller graphite crystallite size (La = 36.54 nm, Lc = 26.75 nm), lower crystallite orientation (Z = 10.21°, R = 0.25), smaller pore size (Rg = 9.56 nm), and higher amorphous carbon content (g = 69.77%, K = 20.38). Consequently, the compressive strength of MPCFRP-B (232 MPa) is enhanced by 30.3% compared to MPCFRP-A.

介相沥青基碳纤维（MPCF）增强聚合物（MPCFRP）复合材料具有优异的导热性和尺寸稳定性，因此在航空航天领域具有巨大的应用潜力。然而，较低的抗压强度严重限制了其在高承载区域的应用。为解决这一问题，我们通过纤维结构调控技术精心制备了具有劈裂径向结构的 MPCF-A 和具有皮芯结构的 MPCF-B。采用拉伸反冲法和原位微柱压缩技术研究了 MPCF 在单丝和微区层面的压缩失效行为。MPCF-A表现出沿石墨层（002）晶面穿透的轴向裂纹导致花瓣状薄片分离的失效模式，芯区的抗压强度（391 兆帕）高于表皮区（360 兆帕）。相反，MPCF-B 在损坏过程中，表皮区域出现大面积横向断裂，同时在核心区域出现均匀的微裂缝。值得注意的是，核心区域的抗压强度（547 兆帕）大大超过了表皮区域的抗压强度（456 兆帕）。此外，MPCF-B 单丝的抗压强度（583 兆帕）高于 MPCF-A（462 兆帕），这归因于较小的石墨结晶尺寸（La = 36.54 nm，Lc = 26.75 nm）、较低的结晶取向（Z = 10.21°，R = 0.25）、较小的孔径（Rg = 9.56 nm）和较高的无定形碳含量（g = 69.77%，K = 20.38）等因素。因此，与 MPCFRP-A 相比，MPCFRP-B 的抗压强度（232 兆帕）提高了 30.3%。

Fully bio-based polylactic acid composites based on molecular crosslinking interface engineering

Kang Chen, Pengrui Chen, Bei Qi, Xinyu Zhang, Lijun Cao, Ce Sun, Haiyan Tan, Yanhua Zhang

doi:10.1016/j.compositesb.2024.111663

基于分子交联界面工程的全生物基聚乳酸复合材料

The key to achieving high-performance plant fiber/polylactic acid (PLA) composites lies in solving the interfacial compatibility issue between the two components. However, current mainstream methods for interfacial modulation often come with energy consumption and environmental concerns. To address this, our study proposed the development of fully bio-based bamboo fiber (BF)/PLA composites based on the principles of non-toxicity, low carbon footprint, and environmental friendliness. In this study, we aimed to construct a molecular-scale multiphase crosslinking network structure in BF/PLA composites. To achieve this, we utilized cyclodextrins (CD) to induce a regularized alignment of PLA molecular chains and employed epoxidized soybean oil (ESO) ring opening reaction to form bonds connecting BF, CD, and PLA molecules. This approach ensured that the composite is fully bio-based while still exhibiting remarkable mechanical properties. The resulting BF/PLA@CD-ESO composites demonstrated impressive bending strength, reaching 108.65 MPa, which was 23.11% higher than that of the BF/PLA composites. Moreover, the tensile strength reached 67.48 MPa, which was 39.06% higher than that of BF/PLA composites. This study provides a convenient, green and sustainable method for preparing PLA-based composites. The resulting composites are expected to be used in disposable tableware, food packaging and environmentally friendly furniture.

实现高性能植物纤维/聚乳酸（PLA）复合材料的关键在于解决两种成分之间的界面相容性问题。然而，目前主流的界面调制方法往往伴随着能耗和环境问题。针对这一问题，我们的研究基于无毒、低碳、环保的原则，提出了开发全生物基竹纤维（BF）/聚乳酸（PLA）复合材料的建议。在本研究中，我们的目标是在 BF/PLA 复合材料中构建分子尺度的多相交联网络结构。为此，我们利用环糊精（CD）诱导聚乳酸分子链规整排列，并采用环氧化大豆油（ESO）开环反应形成连接 BF、CD 和聚乳酸分子的键。这种方法确保了复合材料完全以生物为基础，同时仍具有显著的机械性能。所制备的 BF/PLA@CD-ESO 复合材料表现出惊人的抗弯强度，达到 108.65 兆帕，比 BF/PLA 复合材料高出 23.11%。此外，拉伸强度达到 67.48 兆帕，比 BF/PLA 复合材料高出 39.06%。本研究为制备聚乳酸基复合材料提供了一种便捷、绿色和可持续的方法。所制备的复合材料有望用于一次性餐具、食品包装和环保家具。

Composites Science and Technology

Fiber bundle deposition model and variable speed printing strategy for in-situ impregnation 3D printing of continuous fiber reinforced thermoplastic composites

Zhenzhen Quan, Cheng Liu, Junjie Li, Xiaohong Qin, Jianyong Yu

doi:10.1016/j.compscitech.2024.110723

用于连续纤维增强热塑性复合材料原位浸渍三维打印的纤维束沉积模型和变速打印策略

In the in-situ impregnation 3D printing of continuous fiber reinforced thermoplastic composites (CFRTPCs) at constant printing speed, in order to pursue higher printing efficiency, a higher speed for printing is adopted generally, which has no effect on the printing of the straight section, but at the same speed of printing at the corner, the printing speed will cause the fiber bundle to deviate from the printing path at the corner, which affects the accurate laying of fiber bundle along the printing path. Obviously, reducing the printing speed is an effective method to improve the print quality at the turn, but printing the entire part at the reduced speed will greatly limit the overall printing speed. However, the problem of different corner angles and shifting points from the straight section of high-speed printing to the corner section of low-speed printing has been puzzling researchers. In this paper, a fiber bundle deposition model has been proposed to reveal the deposition of fiber bundles, and the maximum offsets of fiber bundles were predicted under different turning angles. Compared with the measured results, the prediction error at different turning angles ranged from -1.07% to 10.30%. Then, combining with the finite element analysis method, the fiber bundle deposition model was adopted to study the effects of printing speeds, and the maximum printing speeds for different printing angles and the variable printing speed strategy have been put forward. The results have revealed that, by using the optimized variable printing speed strategy, the surface quality of the fabricated parts and the deposition of the fiber bundles along the designed printing path were significantly improved. The fiber bundle deposition model and the variable speed printing strategy could be helpful for the high-precision 3D printing of CFRTPCs.

在匀速原位浸渍三维打印连续纤维增强热塑性复合材料（CFRTPC）时，为了追求更高的打印效率，一般采用较高的打印速度，这对直线部分的打印没有影响，但在转角处以同样的速度打印时，打印速度会使纤维束在转角处偏离打印路径，影响纤维束沿打印路径的准确铺设。显然，降低印刷速度是提高转角处印刷质量的有效方法，但以降低的速度印刷整个部件会大大限制整体印刷速度。然而，从高速印刷的直线段到低速印刷的转角段，转角角度和移位点不同的问题一直困扰着研究人员。本文提出了一种纤维束沉积模型来揭示纤维束的沉积，并预测了不同转角下纤维束的最大偏移量。与实测结果相比，不同转角下的预测误差在-1.07%到10.30%之间。然后，结合有限元分析方法，采用纤维束沉积模型研究了印刷速度的影响，提出了不同印刷角度下的最大印刷速度和变速印刷策略。结果表明，通过采用优化的变速印刷策略，制件的表面质量和纤维束在设计印刷路径上的沉积情况都得到了显著改善。纤维束沉积模型和变速打印策略有助于 CFRTPC 的高精度三维打印。

来源：复合材料力学仿真Composites FEM

【新文速递】2024年7月2日固体力学SCI期刊最新文章

今日更新：Thin-Walled Structures 2 篇Thin-Walled StructuresExperimental study on compressive capacity of stainless steel S35657 columns with welded box section and I-section under axial compressionTiangui Xu, Shengjie Duan, Shenggang Fan, Ganping Shu, Xianyun Shi, Meijing Liudoi:10.1016/j.tws.2024.112178带焊接箱形截面和工字截面的不锈钢 S35657 柱在轴向压缩下的抗压能力实验研究Compared with conventional stainless steel, a new type of stainless steel, S35657, has broad application prospects owing to its advantages of high strength and low production costs. In this study, the compressive capacity of stainless steel S35657 columns was investigated. A total of 13 specimens were designed and tested, including 4 box section specimens and 9 I-section specimens (4 buckling around the major axis and 5 buckling around the minor axis). Complementary chemical composition analyses, material tensile tests, residual stress measurements, and initial geometric imperfection measurements were also conducted. The mechanical properties of the material, as well as its residual stress distribution model, failure mode, load-displacement curve, and compressive capacity, were reported and analyzed. For box section columns, when the slenderness ratio increased from 29 to 55.2, the compressive capacity of the column decreased by 27.6%. The accuracy and safety of design methods specified in European standard EN 1993-1-4, American specification ASCE-8-02, and Chinese specification CECS 410 were assessed based on the test results. The result shows that EN 1993-1-4 is overly conservative in its compressive capacity calculations, whereas ASCE-8-02 overestimates the compressive capacity with a higher level of scatter exhibited. The methods of CECS 410 for predicting the compressive capacity of welded stainless steel S35657 columns are more accurate compared with the methods of EN 1993-1-4 and ASCE-8-02.与传统不锈钢相比，新型不锈钢 S35657 具有强度高、生产成本低的优点，应用前景十分广阔。本研究调查了不锈钢 S35657 柱的抗压能力。共设计和测试了 13 个试件，包括 4 个箱形截面试件和 9 个工字截面试件（4 个绕主轴屈曲，5 个绕次要轴屈曲）。此外，还进行了化学成分分析、材料拉伸试验、残余应力测量和初始几何缺陷测量。报告和分析了材料的机械性能及其残余应力分布模型、失效模式、载荷-位移曲线和抗压能力。对于箱形截面柱，当细长比从 29 增加到 55.2 时，柱子的抗压能力下降了 27.6%。根据测试结果，评估了欧洲标准 EN 1993-1-4、美国规范 ASCE-8-02 和中国规范 CECS 410 中规定的设计方法的准确性和安全性。结果表明，EN 1993-1-4 在计算抗压能力时过于保守，而 ASCE-8-02 则高估了抗压能力，并表现出较高的分散性。与 EN 1993-1-4 和 ASCE-8-02 的方法相比，CECS 410 预测焊接不锈钢 S35657 柱抗压能力的方法更为精确。Stress Concentration Factors for RHS-to-RHS T-Type Moment-Loaded End ConnectionsAli Ziaeinejad, Kyle Tousignant, Min Sun, Zhiyuan Yangdoi:10.1016/j.tws.2024.112179RHS 对 RHS T 型矩载端接的应力集中系数The research presented in this paper is the continuation of a series of efforts to develop design formulae for rectangular hollow section (RHS)-to-RHS end connections and circular hollow section (CHS)-to-CHS end connections under fatigue loading. Normalized hot spot strains for the RHS-to-RHS T-type moment-loaded end connections (unreinforced and reinforced with a chord-end cap plate) are experimentally determined and compared to those in their regular connection counterparts (with sufficient chord continuity). Upon validation using the experimental data, a parametric finite-element study consisting of 448 models (including 336 stepped connections and 112 matched connections) is performed. The parametric study investigates the effects of chord end distance-to-width, branch-to-chord width, branch-to-chord thickness, and chord slenderness ratios, as well as the chord boundary condition (unreinforced or with a chord-end cap plate). Existing formulae in CIDECT Design Guide 8 for the calculation of the corresponding stress concentration factors (SCFs) are evaluated, and SCF correction factors are derived.本文介绍的研究是一系列工作的延续，这些工作旨在开发疲劳载荷下矩形空心截面 (RHS) 到 RHS 端接和圆形空心截面 (CHS) 到 CHS 端接的设计公式。通过实验确定了 RHS 对 RHS T 型时刻加载端部连接（未加固和使用弦端盖板加固）的归一化热点应变，并将其与普通连接（具有足够的弦连续性）的热点应变进行了比较。在使用实验数据进行验证后，对 448 个模型（包括 336 个阶梯连接和 112 个匹配连接）进行了有限元参数研究。参数研究调查了弦端距离与宽度、分支与弦宽度、分支与弦厚度、弦纤度比以及弦边界条件（无加固或有弦端盖板）的影响。对 CIDECT 设计指南 8 中用于计算相应应力集中系数 (SCF) 的现有公式进行了评估，并得出了 SCF 修正系数。来源：复合材料力学仿真Composites FEM