今日更新:Composite Structures 3 篇,Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 2 篇
A comprehensive analysis of low velocity impact response of [0/±45/90]s thin woven GFRP composites at room temperature
U.A. Khashaba
doi:10.1016/j.compstruct.2024.118160
[0/±45/90]s薄编织GFRP复合材料室温低速冲击响应综合分析
This study is motivated by the need to explore the low-velocity impact behavior of angle-ply thin woven GFRP composites with stacking sequence of [0/±45/90]s, especially the lack of literature concerning damage analysis correlation with a comprehensive range of measurements. The damage diameter, area, and perimeter length are characterized in this study by a novel AutoCAD image processing technique. The test results revealed that specimens subjected to impact energies in the range of 2–30 J are free from edge delamination compared to those tested at 40–50 J. Decreasing the contact duration at impact energy of 60 J is due to perforation accompanied with damage propagation toward the specimen edges and thus, the contact force is sharply dropped from its maximum value of about 4.48kN to 1.3kN. Consequently, both rebound speed and coefficient of restitution dropped to zero. The direct measurement of the energy threshold is increased in the following order: energy threshold at Fmax (2.3–14.9 J), first penetration (load drop) after peak load (23.9–25.6 J), penetration energy threshold (37.9 J), perforation energy threshold (31.1 J), and perforation and crack propagation energies (43.3 J). The perimeter length represents a novel damage parameter, exhibiting a strong correlation with impact energy, as evidenced by a high coefficient of determination of 0.97.
本研究的动机是探索堆叠顺序为 [0/±45/90]s 的角层薄编织 GFRP 复合材料的低速冲击行为,尤其是缺乏与全面测量相关的损伤分析文献。本研究采用新颖的 AutoCAD 图像处理技术对损伤直径、面积和周长进行了表征。试验结果表明,受到 2-30 J 冲击能量的试样与受到 40-50 J 冲击能量的试样相比,不会出现边缘分层现象。在受到 60 J 冲击能量时,接触持续时间缩短,这是由于穿孔伴随着损伤向试样边缘扩展,因此接触力从最大值约 4.48kN 骤降至 1.3kN。因此,回弹速度和恢复系数都降至零。能量阈值的直接测量值按以下顺序增加:Fmax 时的能量阈值(2.3-14.9 J)、峰值载荷后的首次穿透(载荷下降)(23.9-25.6 J)、穿透能量阈值(37.9 J)、穿孔能量阈值(31.1 J)以及穿孔和裂纹扩展能量(43.3 J)。周长是一个新的损伤参数,与冲击能量有很强的相关性,其决定系数高达 0.97。
Progressive failure simulation of angled composite beams subject to flexural loading
James Roach, Dianyun Zhang
doi:10.1016/j.compstruct.2024.118111
弯曲荷载作用下斜向组合梁的递进破坏模拟
Laminated composite structures, while offering weight savings compared with their metal counterparts, are susceptible to ply separation, (i.e., delamination mode of failure) due to the lack of through-thickness fiber reinforcements. In this paper, numerical simulations are used to gain an enhanced understanding of angled composite beam delamination when subjected to four-point bending consistent with the ASTM D-6415 test standard, with an expectation that the learning gained from this work is extensible to laminated composite components in general. While illustrating mesh sensitivity, manufacturing and frictional effects, four items of interest are examined: (1) the undamaged state/pre-peak load response, (2) the through-thickness peak tensile capability, (3) the post-peak load drop, and (4) the subsequent post-peak damaged response. A Finite Element Analysis (FEA) model is developed that incorporates the Smeared Crack Approach (SCA) to capture progressive failure modes within the element formulations directly, effectively eliminating the need for a priori specification of discrete delamination zones. The ability to incorporate failure directly within the element structure is particularly notable where laminates may not realistically permit a high number of interface layers or where geometry may be complex. Leveraging experimental data of curved composite laminates subject to four-point bending, the proposed approach successfully predicts the correct behavior throughout the damage progression. Additionally, this study offers an insight into effects of manufacturing-induced imperfections and frictions between the specimen and fixture on the prediction of inter-laminar strength of a curved composite part.
与金属复合材料相比,层压复合材料结构虽然减轻了重量,但由于缺乏贯穿厚度的纤维增强,容易发生层分离(即分层模式失效)。在本文中,数值模拟是为了更好地理解在符合ASTM D-6415测试标准的四点弯曲下的角度复合材料梁的分层,并期望从这项工作中获得的知识可以扩展到一般的层压复合材料部件。在说明网格灵敏度、制造和摩擦效应的同时,研究了四个感兴趣的项目:(1)未损坏状态/峰前负载响应,(2)贯穿厚度的峰值拉伸能力,(3)峰后负载下降,以及(4)随后的峰后损坏响应。开发了一种有限元分析(FEA)模型,该模型结合了涂抹裂纹方法(SCA)来直接捕获元件配方中的渐进失效模式,有效地消除了对离散分层区域的先验规范的需要。当层压板实际上不允许大量的界面层或几何结构可能很复杂时,将失效直接合并到元件结构中的能力尤其值得注意。利用弯曲复合材料层合板的四点弯曲实验数据,该方法成功地预测了整个损伤过程中的正确行为。此外,本研究还深入了解了制造缺陷和试样与夹具之间的摩擦对弯曲复合材料零件层间强度预测的影响。
Reducing Cf/SiC composite damages through collaborative control of laser ablating depth and grinding modes
Guijian Xiao, Xin Li, Kun Zhou, Yi He, Zhengyu Yang
doi:10.1016/j.compstruct.2024.118158
通过协同控制激光烧蚀深度和磨削方式减少Cf/SiC复合材料损伤
Cf/SiC composites are regarded as difficult-to-machine aerospace materials. A low-damage surface machining of Cf/SiC composite by laser-ablating assisted grinding (LAAG) was conducted, and investigated the effects of laser-ablating depth and grinding modes on surface/subsurface damages. The results showed that ablated material depth reached 420 μm after 1200 times scanning, while the effective ablating rate was inhibited by the depth. Compared with down grinding, the grinding forces and temperatures were substantially higher in up grinding, with a maximum increase of 123.5% and 140% in normal and tangential grinding forces, respectively; however, micro brittle fracture and ductile removal were remarkably enhanced in normal and transverse fibers, and surface macroscopic damage has been suppressed; subsurface damage remained insignificant, mainly exhibited in internal micro cracks and minor interfacial debonding. It was attributed to cutting characteristics of up grinding. Furthermore, as grinding depth increased, the material removal behavior underwent a brittle-ductile transition and the surface roughness grew accordingly. Moreover, a laser scanning angle of 0° and up grinding facilitated the occurrence of longitudinal fiber debonding, producing larger sized fiber bundle chips. Combining up grinding with 90° scanning angle at low grinding depth was an effective method to improve the surface quality of Cf/SiC composite.
Cf/SiC复合材料被认为是难以加工的航空航天材料。采用激光烧蚀辅助磨削(LAAG)技术对Cf/SiC复合材料进行了低损伤表面加工,研究了激光烧蚀深度和磨削方式对表面/亚表面损伤的影响。结果表明:经1200次扫描后,烧蚀材料深度达到420 μm,有效烧蚀速率受深度的抑制;与向下磨削相比,向上磨削的磨削力和磨削温度显著增大,法向磨削力和切向磨削力分别最大增大123.5%和140%;而在正向纤维和横向纤维中,微脆性断裂和韧性去除明显增强,表面宏观损伤受到抑制;亚表面损伤不明显,主要表现为内部微裂纹和少量界面剥离。这是由于上磨的切削特性造成的。随着磨削深度的增加,材料的去除行为发生脆性-韧性转变,表面粗糙度随之增大。此外,激光扫描角度为0°,向上磨削有利于纵向光纤脱粘的发生,产生较大尺寸的光纤束切屑。低磨削深度下90°扫描角联合磨削是提高Cf/SiC复合材料表面质量的有效方法。
Tensile strength prediction of unidirectional polyacrylonitrile (PAN)-based carbon fiber reinforced plastic composites considering stress distribution around fiber break points
Go Yamamoto, Kenta Oshima, Redha Akbar Ramadhan, TaeGyeong Lim, Yonas Tsegaye Megra, Ji Won Suk, Jun Watanabe, Haruki Okuda, Fumihiko Tanaka
doi:10.1016/j.compositesa.2024.108234
考虑纤维断裂点应力分布的单向聚丙烯腈基碳纤维增强塑料复合材料抗拉强度预测
Recent advancements in enhancing the mechanical characteristics of carbon fibers open up new application possibilities for carbon fibre-reinforced plastic (CFRP) composites. Particularly in unidirectional CFRPs, which form the basal structure of CFRP laminates, developing a micromechanics model capable of predicting the tensile strength of unidirectional CFRPs based on carbon fiber mechanical characteristics is a current aspiration. This study conducted a stress distribution analysis around the fiber fracture point to predict the tensile strengths of unidirectional CFRPs prepared with five types of polyacrylonitrile (PAN)-based carbon fibers, each with unique mechanical characteristics. Numerical simulation results obtained using a unidirectional CFRP model that considered the stress concentration, fiber axial stress, and bimodal Weibull distribution were reasonably consistent with the experimental results for the tensile strengths of unidirectional CFRP composites, regardless of the differences in the mechanical characteristics of the fiber. Our findings can provide guidance for designing further enhanced high-performance CFRP materials.
最近在提高碳纤维力学特性方面的进展为碳纤维增强塑料(CFRP)复合材料的应用开辟了新的可能性。特别是在单向碳纤维复合材料中,它构成了碳纤维复合材料层合板的基本结构,基于碳纤维的力学特性,开发一种能够预测单向碳纤维复合材料抗拉强度的微观力学模型是当前的一个愿望。本研究对纤维断裂点周围的应力分布进行了分析,以预测五种具有独特力学特性的聚丙烯腈(PAN)基碳纤维制备的单向cfrp的拉伸强度。考虑应力集中、纤维轴向应力和双峰Weibull分布的单向CFRP模型的数值模拟结果与实验结果基本一致,且不考虑纤维力学特性的差异。研究结果可为进一步设计高性能CFRP材料提供指导。
Design of Functionally Gradient Metastructure with Ultra-broadband and Strong Absorption
Chengtao Sun, Dawei Li, Tingting Liu, Qing An, Changdong Zhang, Yaoyao Li, Wenhe Liao
doi:10.1016/j.compositesb.2024.111484
超宽带强吸收功能梯度元结构设计
Rational design principles for ultra-broadband lattice-based metastructure absorbers (MMAs) remain scarcely explored, including elucidation of the governing absorption phenomena. This work presents Octet truss lattices gradient-tailored to achieve highly efficient wide-spectrum electromagnetic (EM) wave mitigation. The optimized 15 mm thick three-dimensional printed architectures comprise three stacked sub-layers with graduated densities spanning a reflective backing. Analysis of unit cell EM responses as a function of geometric parameters facilitates concurrent broadband absorption and minimal mass. Consequently, ultra-wideband absorption below -10 dB persists from 2.84-40.0 GHz under normal incidence, with strongly enhanced attenuation below -15 dB between 8.51-40.0 GHz. Additionally, consistent absorption capacity endures up to 60° for both transverse electric (TE) and transverse magnetic (TM) polarizations, empowered by the intricate conductive networks established through wave interactions. The unique combination of additive manufacturing, hierarchical metamaterial engineering, and physical insights provides a versatile strategy for customized broadband absorption systems across application domains.
超宽带晶格基元结构吸波器(MMAs)的合理设计原则仍然很少被探索,包括对控制吸收现象的阐明。这项工作提出了八元桁架晶格梯度定制,以实现高效的广谱电磁(EM)波减缓。优化的15毫米厚的三维打印结构包括三个堆叠的子层,其密度跨越反射背衬。分析作为几何参数函数的单元格电磁响应有助于同时宽带吸收和最小质量。因此,在正常入射下,在2.84-40.0 GHz范围内-10 dB以下的超宽带吸收持续存在,在8.51-40.0 GHz范围内-15 dB以下的衰减强烈增强。此外,由于通过波相互作用建立的复杂导电网络,横向电(TE)和横向磁(TM)极化的持续吸收能力可达60°。增材制造、分层超材料工程和物理洞察的独特结合,为跨应用领域的定制宽带吸收系统提供了一种通用策略。
A combination of "Inner - Outer skeleton" strategy to improve the mechanical properties and heat resistance of polyimide composite aerogels as composite sandwich structures for space vehicles
Qi Sun, Kun Tian, Sihan Liu, Qing Zhu, Shuai Zheng, Jing Chen, Liping Wang, Si Cheng, Zhen Fan, Si Cheng, Xupeng Fan, Dezhi Wang, Chunyan Qu, Changwei Liu
doi:10.1016/j.compscitech.2024.110620
采用“内外骨架”相结合的策略提高聚酰亚胺复合气凝胶的力学性能和耐热性,作为航天飞行器的复合夹层结构
Low density aerogels with high fatigue resistance are widely used in the manufacturing of core material structures in aircraft fuselage to be able to tolerate the extreme environment of aerospace. However, most organic aerogel materials have poor energy absorption of external impact forces, and are prone to irreversible deformation, such as contracture and collapse in the process of long-term service. In order to solve this problem, a new type of thermosetting-thermoplastic polyimide composite aerogel was prepared, with its microstructure presenting the coexistence of the inner and outer skeletons. The intermolecular forces promoted the assembly of the soft thermoplastic layer and the strong thermosetting layer in the thermodynamic process with 4.63 to 6.55 μm range. The hard-soft layer structure improved the compressive and the shear load bearing capacities by bending of the panel (Compressive modulus is 1.60MPa to 3.52MPa, tensile modulus is 1.04MPa to 1.45MPa). Its permanent degradation less than 1.5% after 500 cycles at 30% strain. C-CPIAs also exhibited excellent heat resistance and thermal insulation performances, with a T5% value of 612 °C (C-CPIA-2), Tg of 458 °C (C-CPIA-3). The sandwich materials can be used as outer protective composite material of aircraft fuselage for future deep space missions.
具有高抗疲劳性能的低密度气凝胶被广泛应用于飞机机身核心材料结构的制造,以适应航空航天的极端环境。然而,大多数有机气凝胶材料对外部冲击力的能量吸收能力较差,在长期服役过程中容易发生挛缩、塌陷等不可逆变形。为了解决这一问题,研究人员制备了一种新型热固性热塑性聚酰亚胺复合气凝胶,其微观结构呈现出内外骨架共存的特点。在 4.63 至 6.55 μm 的热力学过程中,分子间作用力促进了软热塑性层和强热固性层的组装。软硬层结构提高了板材的抗压和抗剪承载能力(抗压模量为 1.60MPa 至 3.52MPa,抗拉模量为 1.04MPa 至 1.45MPa)。在 30% 的应变下循环 500 次后,其永久降解率小于 1.5%。C-CPIA 还具有优异的耐热性和隔热性能,其 T5% 值为 612 ℃(C-CPIA-2),Tg 为 458 ℃(C-CPIA-3)。这种夹层材料可用作飞机机身的外层保护复合材料,用于未来的深空任务。
Fire behavior and post-fire residual tensile strength prediction of carbon fiber/phthalonitrile composite laminates
Jinchuan Yang, Chunming Ji, Dongqing Wang, Hanqi Zhang, Zhengong Zhou, Jiqiang Hu, Bing Wang
doi:10.1016/j.compscitech.2024.110624
碳纤维/邻苯二腈复合层压板的火灾行为及火灾后残余拉伸强度预测
Carbon fiber/phthalonitrile (Cf/PN) composite has a high potential for applications in the aerospace sector because of the outstanding heat and flame resistance of phthalonitrile resin. Here we aim to evaluate the fire behavior of Cf/PN laminate under localized one-sided flame heating as well as the residual tensile performance. The residual tensile strength after quasi-isothermal pyrolysis in an inert environment decreases linearly with the increase in the pyrolysis degree. The temperature response and pyrolysis behavior are analyzed through a combination of experiments and finite element simulations, and the damage mode of the laminate structure is concluded through morphological observation after flame exposure and the surface axial strain field using digital image correlation. Eventually, the residual tensile strength of laminates with different thicknesses after different times of flame exposure was effectively predicted based on the numerical simulated pyrolysis degree distribution. This research supplies fundamental test data on the mechanical properties of Cf/PN laminates and is expected to provide guidelines for the engineering application of Cf/PN composites in thermal protection/load-bearing all-in-one structures.
碳纤维/邻苯二腈(Cf/PN)复合材料具有优异的耐热性和阻燃性,在航空航天领域具有很大的应用潜力。本文旨在评价Cf/PN层合板在局部单侧火焰加热下的燃烧行为以及残余拉伸性能。惰性环境下准等温热解后的残余抗拉强度随热解程度的增加而线性降低。通过实验与有限元模拟相结合的方法分析了层压板结构的温度响应和热解行为,并通过火焰暴露后的形态观察和数字图像相关的表面轴向应变场得出层压板结构的损伤模式。最后,基于数值模拟热解度分布,有效预测了不同厚度层压板在不同火焰暴露次数后的残余拉伸强度。本研究为Cf/PN复合材料的力学性能提供了基础试验数据,有望为Cf/PN复合材料在热防护/承重一体化结构中的工程应用提供指导。