今日更新:Composite Structures 5 篇,Composites Part B: Engineering 1 篇
A review of prediction methods for global buckling critical loads of pultruded FRP struts
Hengming Zhang, Feng Li
doi:10.1016/j.compstruct.2023.117752
拉挤玻璃钢支柱全局屈曲临界载荷预测方法综述
Pultruded fiber-reinforced composites (FRP) are widely used in structural engineering due to their excellent properties along the fiber direction. Its global buckling performance has received increasing attention from academia and engineering. This paper reviews the prediction methods for the critical buckling load of pultruded FRP struts, including the Euler formula critical load prediction method, the shear-corrected critical load prediction method, the Southwell plot method, and the critical load prediction method based on the strength failure mode. Summarizes the basic principles of each method, discusses the internal relationship and difference of each method, and analyzes the critical factors of each method with experimental data. In addition, a unified generalized Ayton-Perry theoretical model is proposed through induction and summary. Finally, based on the experimental database, a Machine learning model for predicting the buckling critical load is established. The results show that the machine learning algorithm can predict the buckling critical load with high prediction accuracy.
拉挤纤维增强复合材料(FRP)因其沿纤维方向的优异性能而被广泛应用于结构工程中。其整体屈曲性能越来越受到学术界和工程界的关注。本文综述了拉挤玻璃钢支柱临界屈曲载荷的预测方法,包括欧拉公式临界载荷预测法、剪切校正临界载荷预测法、Southwell plot 法和基于强度失效模式的临界载荷预测法。总结了每种方法的基本原理,讨论了每种方法的内在关系和区别,并结合实验数据分析了每种方法的关键因素。此外,通过归纳和总结,提出了统一的广义艾顿-佩里理论模型。最后,基于实验数据库,建立了预测屈曲临界载荷的机器学习模型。结果表明,机器学习算法能以较高的预测精度预测屈曲临界载荷。
Explicit analytical solutions for the full plane-stress field in sandwich beams under flexure governed by zigzag warping
Lorenzo Bardella
doi:10.1016/j.compstruct.2023.117754
受之字形翘曲约束的弯曲夹层梁全平面应力场的显式解析解
We provide analytical solutions for the full stress field of straight sandwich beams with identical skins subject to linear elastic flexure governed by zigzag warping, where all layers obey Timoshenko’s kinematics. As a main novelty, we make use of an equilibrium equation for the Cauchy continuum to recover of the through-the-thickness normal stress component, σ y . The new estimates are accurate for a wide range of relative stiffness between skins and core and suitable boundary conditions, as it can be demonstrated through the comparison with detailed finite element simulations where the sandwich is modelled as a two-dimensional continuum. As a main practical result concerned with the study of delamination, we find that at a core–skin interface of a cantilever sandwich subjected to a uniformly distributed load, in a region close to the fully-clamped cross-section, σ y is a tensile stress of magnitude larger than that of the shear stress. On this basis, we infer that the availability of good estimates for σ y , along with those for the longitudinal and shear stresses, may be important for the accurate design of sandwich panels.
我们提供了受人字形翘曲线性弹性弯曲支配的具有相同表皮的直线夹层梁的全应力场分析解,其中所有层均服从季莫申科运动学。作为一项主要创新,我们利用考奇连续体平衡方程恢复了厚度法向应力分量 σ y 。通过与将夹层作为二维连续体建模的详细有限元模拟进行比较,可以证明新的估计值在表皮与夹层之间相对刚度范围较大以及合适的边界条件下都是准确的。作为与分层研究有关的主要实际结果,我们发现在悬臂夹层的夹芯-蒙皮界面上,在靠近完全夹紧横截面的区域,σ y 是一个拉应力,其大小大于剪应力。在此基础上,我们推断σ y 以及纵向应力和剪应力的良好估计值对于夹芯板的精确设计非常重要。
Optimization of fracture toughness in 3D-printed parts: Experiments and numerical simulations
Mohammad Reza Khosravani, Hadi Sadeghian, Majid R. Ayatollahi, Tamara Reinicke
doi:10.1016/j.compstruct.2023.117766
优化 3D 打印部件的断裂韧性:实验和数值模拟
Since additive manufacturing (AM) has been utilized for production of functional end-use parts, the mechanical behavior of the additively manufactured parts is a crucial issue. In the present study, compact tension (CT) test is conducted on 3D-printed polymer parts which are fabricated based on the fused deposition modeling (FDM) technique. Considering the influence of the printing parameters on the mechanical performance of the parts, the specimens are fabricated under different printing parameters. In detail, CT specimens are printed with +45°/−45° and 0°/90° filament directions and 0.2 and 0.5 mm layer thicknesses at printing speed of 20 mm/s and 70 mm/s. Based on the CT tests, the fracture behavior of the parts are investigated and their fracture toughness are determined. In addition, digital image correlation technique is used to determine the strain fields on the surface of the CT specimens. Moreover, a series of finite element analysis is performed to study the mechanical behavior of modeled parts. Additionally, scanning electron microscopic investigation is performed for visual examination of the fractured components. According to the results, optimum printing parameters for maximizing the mechanical properties are determined. Due to the wide applications of the FDM 3D-printed parts, the documented results are beneficial for fabrication of parts with a higher mechanical strength.
由于增材制造(AM)已被用于生产终端功能部件,因此增材制造部件的机械性能是一个至关重要的问题。本研究对基于熔融沉积建模(FDM)技术制造的三维打印聚合物部件进行了紧凑拉伸(CT)测试。考虑到打印参数对零件机械性能的影响,试样是在不同的打印参数下制作的。具体来说,CT 试样是在 +45°/-45° 和 0°/90° 长丝方向、0.2 和 0.5 mm 层厚、20 mm/s 和 70 mm/s 印刷速度下印刷的。根据 CT 测试,研究了部件的断裂行为并确定了其断裂韧性。此外,还利用数字图像相关技术确定了 CT 试样表面的应变场。此外,还进行了一系列有限元分析,以研究建模零件的机械行为。此外,还利用扫描电子显微镜对断裂部件进行了直观检查。根据研究结果,确定了最大化机械性能的最佳印刷参数。鉴于 FDM 3D 打印部件的广泛应用,所记录的结果有利于制造具有更高机械强度的部件。
A novel prefabricated auxetic honeycomb meta-structure based on mortise and tenon principle
Yilin Zhu, Defeng Gao, Yongbo Shao, Hui Chen, Chao Yu, Qingyuan Wang
doi:10.1016/j.compstruct.2023.117782
基于榫卯原理的新型预制辅助蜂窝元结构
Existing auxetic honeycomb meta-structures are generally integrated structures with complicated microstructural geometry which hence should be fabricated by costly additive manufacturing (AM) technology. The high cost and low production efficiency of AM technology is still the main bottleneck restricting the engineering applications of such kind of structures. In this work, a prefabricated auxetic honeycomb meta-structure with modularized components was proposed based on mortise and tenon (M&R) principle originated in ancient China. The modularized components of the prefabricated auxetic honeycomb are all tubular structures which can be easily fabricated by traditional manufacturing with low cost and high technical maturity. The mechanical properties of the proposed meta-structure were then detailed investigated numerically under quasi-static and dynamic loading conditions. The referenced integrated auxetic honeycomb meta-structure was also considered as a benchmark for comparison. Results show that the proposed prefabricated design exhibits lower strength and stiffness compared with its integrated counterpart, owing to the introduction of more flexibility. Consequently, the proposed design processes a much more stable stress plateau stage with a larger deformation range and effectively reduces the reactive force of the protected structure. The present work paves a novel avenue to design protective meta-structures with low-cost and high performance.
现有的助熔蜂窝元结构一般都是具有复杂微观几何结构的集成结构,因此必须采用成本高昂的增材制造(AM)技术来制造。AM 技术的高成本和低生产效率仍然是制约此类结构工程应用的主要瓶颈。本研究基于中国古代的榫卯原理,提出了一种具有模块化组件的预制辅助蜂窝元结构。预制辅助蜂窝的模块化组件均为管状结构,可通过传统制造工艺轻松制造,成本低,技术成熟度高。随后,在准静态和动态加载条件下,对所提出的元结构的力学性能进行了详细的数值研究。同时还将参考的集成辅助蜂窝元结构作为比较基准。结果表明,由于引入了更多的灵活性,拟议的预制设计与集成设计相比,强度和刚度更低。因此,拟议设计的应力平台阶段更为稳定,变形范围更大,并有效降低了受保护结构的反作用力。本研究为设计低成本、高性能的保护性元结构开辟了一条新途径。
Damage behavior of high particle volume fraction composites with initial damage by finite element meso-modeling
Xiaoshan Zhang, Guoqiang Luo, Haohan Zhou, Qinqin Wei, Xiaoyu Yang, Yuxuan Zhu, Peng Cao, Qiang Shen
doi:10.1016/j.compstruct.2023.117785
通过有限元中观建模研究具有初始损伤的高颗粒体积分数复合材料的损伤行为
Analyzing the deformation and damage processes of high particle volume fraction composites (HPVFCs) based on the meso-structure modeling plays an important role in their service lifetime and functional reliability. The reported mesoscopic structural models are usually ideal models without initial damage and apply to composites with the volume fraction of particles less than 80%. This work provides a new mesoscopic structure model called aggregate settlement-merging model to successfully simulate the mechanical behavior and damage mechanism of the polymer-bonded explosive (PBX) under quasi-static loads, and the macroscopic response is accurately predicted by the cohesive finite element method. This simulation commendably predicts the failure modes including interface debonding, binder filaments, and grain failure, which is consistent with the observation in micromechanical experiments. The multi-scale relationship between macroscopic mechanical properties and microscopic initial interface damage is quantitatively established in a form of an exponential function. This study shows a relationship between meso-structures and performance and provides strategy for designing next generation high-performance HPVFCs.
基于中观结构模型分析高颗粒体积分数复合材料(HPVFCs)的变形和损伤过程对其使用寿命和功能可靠性具有重要作用。已报道的中观结构模型通常是无初始损伤的理想模型,适用于颗粒体积分数小于 80% 的复合材料。本研究提供了一种新的介观结构模型--聚合沉降-合并模型,成功模拟了聚合物粘结炸药(PBX)在准静载荷下的力学行为和损伤机理,并通过内聚有限元法准确预测了宏观响应。模拟预测了包括界面脱开、粘结丝和晶粒破坏在内的破坏模式,这与微机械实验的观察结果一致。宏观力学性能与微观初始界面损伤之间的多尺度关系以指数函数的形式定量确定。这项研究表明了介观结构与性能之间的关系,并为设计下一代高性能 HPVFC 提供了策略。
Simulated end-of-life reuse of composites from marine applications using thermal reshaping of seawater-aged, glass fibre-reinforced acrylic materials
Michael Noonan, Winifred Obande, Dipa Ray
doi:10.1016/j.compositesb.2023.111118
通过对海水老化的玻璃纤维增强丙烯酸材料进行热重塑,模拟海洋应用中复合材料的报废再利用情况
In this work, end-of-life reuse of continuous fibre-reinforced thermoplastic composites from marine applications has been simulated by thermally reshaping (reprocessing) seawater-aged materials. Specifically, resin-infused, V-shaped glass/acrylic composites were seawater-aged (60 °C; 170 h) and reprocessed in a heated hydraulic press (120 °C; 10 bar). Reprocessing promoted void collapse and increased short beam shear strengths. Unaged reprocessed materials retained 52 % and 57 % performance in flexural strength and modulus, (relative to virgin material), with corresponding retentions of 20 % and 62 % in the aged reprocessed materials, respectively. Ageing- and reprocessing-related flexural performance changes occurred due to mild matrix plasticisation and fibre misalignment, respectively.
在这项工作中,通过对海水老化材料进行热重塑(再加工),模拟了海洋应用中连续纤维增强热塑性复合材料的报废再利用。具体来说,将注入树脂的 V 形玻璃/丙烯酸复合材料进行海水老化(60 °C;170 小时),然后在加热液压机中进行再加工(120 °C;10 巴)。再加工促进了空隙塌陷,提高了短梁剪切强度。未老化的后处理材料在抗弯强度和模量方面分别保持了 52% 和 57% 的性能(相对于原始材料),而老化的后处理材料则分别保持了 20% 和 62% 的性能。与老化和再加工相关的弯曲性能变化分别是由于轻微的基体塑化和纤维错位造成的。