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【新文速递】2024年11月27日复合材料SCI期刊最新文章

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今日更新:Composite Structures 3 篇,Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 3 篇,Composites Science and Technology 1 篇

Composite Structures

A multi-scale uncertainty analysis method based on the Hermite-Chebyshev polynomials for dynamic responses of FRP composite structures with hybrid uncertainties

Sheng-Yu Qian, Xiao-Yi Zhou, Neng-Wei Wang

doi:10.1016/j.compstruct.2024.118713

混合不确定性FRP复合材料结构动力响应的Hermite-Chebyshev多项式多尺度不确定性分析方法

Multi-scale hybrid uncertainties in material properties of FRP composites stemming from their manufacturing processes present significant challenges for dynamic analysis and reliability assessment. This paper proposes a multi-scale uncertainty surrogate model based on Hermite-Chebyshev polynomials. The relationship between micro- and macro-scale material properties is established using the Mori–Tanaka method. To demonstrate the efficacy of the proposed method, case studies are conducted on both a FRP wide-flange I-beam structure and a FRP truss bridge. Results indicate that this method accurately determines the probability density functions and cumulative distribution functions of natural frequencies and mode shapes. Notably, the method efficiently computes the upper and lower bounds of dynamic failure probability of FRP truss bridge with high numerical efficiency.

FRP复合材料性能的多尺度混合不确定性来源于其制造工艺,这对动态分析和可靠性评估提出了重大挑战。提出了一种基于Hermite-Chebyshev多项式的多尺度不确定性替代模型。采用Mori-Tanaka方法建立了材料微观和宏观性能之间的关系。为了证明该方法的有效性,对玻璃钢宽翼缘工字梁结构和玻璃钢桁架桥进行了实例研究。结果表明,该方法准确地确定了固有频率和振型的概率密度函数和累积分布函数。值得注意的是,该方法能够高效地计算FRP桁架桥梁动力破坏概率的上下界,具有较高的数值效率。


Numerical prediction of impact damage in thick fabric composite laminates

Niels van Hoorn, Sergio Turteltaub, Christos Kassapoglou, Wouter van den Brink

doi:10.1016/j.compstruct.2024.118726

厚织物复合材料层合板冲击损伤的数值预测

A simulation methodology for assessing the damage in thick fabric Carbon Fibre Reinforced Polymer (CFRP) composite laminates under low- and high-velocity impacts is presented. It encompasses steps for calibration, verification, and validation of the elastic and fracture material properties as well as determination of model parameters for the numerical simulations. Damage is modelled using a discrete fracture approach with cohesive interface elements that capture individual cracks occurring in and between plies. For computational efficiency, the method is implemented in a two-dimensional (2D) axi-symmetric model. Results from double-cantilever beam, end-notched flexure, and quasi-static indentation experiments align well with numerical simulations and serve to calibrate and verify the implementation of the discrete fracture approach. The methodology is extended to dynamic impact analysis to predict damage mechanisms, force–displacement histories, and is validated using test results. This methodology combines meaningful insight in the failure mechanisms with a manageable computational effort, achieving a factor 50 improvement compared to a benchmark. A parametric analysis summarised in failure maps relates damage mechanisms to impact energy, mass, and laminate thickness. The proposed methodology strikes a balance between computational efficiency and accuracy, making it a valuable tool for optimum design and certification of thick CFRP composite laminates under impact.

提出了一种评估厚织物碳纤维增强聚合物(CFRP)复合材料层合板在低速和高速碰撞下损伤的仿真方法。它包括步骤的校准,验证,并确认弹性和断裂材料的性能,以及确定模型参数的数值模拟。损伤建模采用离散断裂方法,具有内聚界面元素,可以捕获层内和层间发生的单个裂缝。为了提高计算效率,该方法采用二维轴对称模型实现。双悬臂梁、端缺口弯曲和准静态压痕实验的结果与数值模拟结果吻合良好,可用于校准和验证离散断裂方法的实现。该方法被扩展到动态冲击分析,以预测损伤机制、力-位移历史,并通过测试结果进行验证。这种方法结合了对故障机制的有意义的洞察和可管理的计算工作,与基准测试相比,实现了50倍的改进。失效图中总结的参数分析将损伤机制与冲击能量、质量和层压厚度联系起来。所提出的方法在计算效率和精度之间取得了平衡,使其成为在冲击下厚CFRP复合材料层合板优化设计和认证的有价值的工具。


Characterization of direct ink writing carbon fiber composite structures with serial sectioning and DREAM.3D

Kenneth M. Clarke, Michael Groeber, John Wertz, Andrew Abbott, Roneisha Haney, Michael Chapman

doi:10.1016/j.compstruct.2024.118730

直接墨水书写碳纤维复合材料结构的连续切片和DREAM.3D表征

Direct Ink Writing (DIW) combines the flexibility of 3D printing with increased material applications such as thermoset carbon fiber composites, ceramic composites, and metals. The usefulness of direct ink writing, like many additive manufacturing (AM) processes, remains limited for reasons ranging from quality control to lack of process parameter optimization. This study looks to introduce a methodology for characterizing direct ink written carbon fiber composites to facilitate exploration into the relationships between process parameters and material structure. The presented study utilized nine 3D specimens of direct ink writing carbon fiber composites printed with varying process parameters - speed differential, layer height, step-over distance, and nozzle diameter - as the data set. The data was collected with an automatic serial sectioning system, LEROY, from the Air Force Research Laboratory. The collected data was processed in DREAM.3D and analyzed with statistical comparisons of 2D orientation distributions of the fibers, 2D size distributions of the voids, and 2D shape distributions of the voids.

直接墨水书写(DIW)结合了3D打印的灵活性和增加的材料应用,如热固性碳纤维复合材料,陶瓷复合材料和金属。与许多增材制造(AM)工艺一样,由于质量控制和缺乏工艺参数优化等原因,直接墨水书写的实用性仍然有限。本研究旨在介绍一种表征直接墨水书写碳纤维复合材料的方法,以促进探索工艺参数与材料结构之间的关系。本研究使用了9个直接墨水书写碳纤维复合材料的3D样品,这些样品具有不同的工艺参数——速度差、层高、台阶距离和喷嘴直径——作为数据集。数据是由空军研究实验室的自动串行切片系统LEROY收集的。将收集到的数据在DREAM.3D中进行处理,统计比较纤维的二维方向分布、空隙的二维尺寸分布和空隙的二维形状分布。


Composites Part A: Applied Science and Manufacturing

Influence of thermoplastic fibre-epoxy adhesion on the interlaminar fracture toughness of interleaved polymer composites

Zaide Saka Dinç, Yahya Öz, Prasad Potluri, William W. Sampson, Hüseyin Aksel Eren

doi:10.1016/j.compositesa.2024.108619

 

热塑性纤维-环氧树脂黏附对交织聚合物复合材料层间断裂韧性的影响

We present an experimental study using surface modification of polyetherimide (PEI) and polyphenylene sulfide (PPS) nonwoven fibrous veils to probe their performance as interleaves to improve the interlaminar fracture toughness (IFT) of carbon fibre-epoxy composites. Veil fibre surfaces were modified with ozone and a post-treatment with ultraviolet (UV) light (ozone + UV). From surface characterisation, mechanical testing of composites and fractography we show that for the PEI veil, these surface modifications resulted in a decreased mode I IFT attributable to decreased fibre-epoxy adhesion and hence, fibre/matrix debonding. In contrast, an increase in sulfinyl functional groups on the surface of PPS fibres after ozonation was observed alongside an increase in PPS veil-epoxy adhesion. The strong bond between fibre–matrix resisted crack propagation across veils, compelling the crack to divert through weaker carbon fibre-epoxy interfaces in adjacent layers. The mode I fracture toughness during crack propagation GIprop decreased, confirming the level of veil-epoxy adhesion to be a significant contributor to the IFT that can be associated with specific functional groups on fibre surfaces.

采用聚醚酰亚胺(PEI)和聚苯硫醚(PPS)非织造纤维纱的表面改性方法,研究了它们作为交织物提高碳纤维-环氧复合材料层间断裂韧性(IFT)的性能。面纱纤维表面用臭氧改性,后处理用紫外线(UV)光(臭氧 + UV)。从表面表征、复合材料的力学测试和断口形貌来看,我们发现对于PEI膜,这些表面改性导致I型IFT降低,这是由于纤维与环氧树脂的粘附性降低,从而导致纤维/基体脱粘。相比之下,在臭氧化后,PPS纤维表面的亚砜基官能团增加,同时PPS涂层-环氧树脂附着力增加。纤维基体之间的强结合抑制了裂纹的扩展,迫使裂纹通过相邻层中较弱的碳纤维-环氧界面转移。裂纹扩展过程中的I型断裂韧性GIprop下降,这证实了纤维表面特定官能团的粘合水平是IFT的重要影响因素。


Composites Part B: Engineering

Ultrastrong and ductile Al-Mg alloy matrix composites via composition-modulated precipitation induced by intragranular ceramic nanoparticles

Zhiqi Guo, Kang Wang, Bo Cui, Zhanqiu Tan, Lei Zhao, Genlian Fan, Zan Li, Zhiqiang Li, Di Zhang

doi:10.1016/j.compositesb.2024.112012

 

晶内纳米陶瓷诱导成分调制析出的超强延展性铝镁合金基复合材料

Nano-precipitation is critical in achieving high yield strength and strain hardening capacity in aluminum alloys and their composites, while Al-Mg alloys and their composites are generally believed not to be strengthened significantly by precipitations. This study reveals that a coherent composition-modulated precipitate χ deviated from the conventional precipitation sequence forms near intragranular ceramic nanoparticles (ICNPs) in Al-Mg alloy matrix composites, providing precipitation strengthening of ∼120 MPa and activating early plastic relaxation around ICNPs. Thus, an Al-5Mg alloy (wt.%) reinforced with 1.5 wt.% carbon nanotubes containing χ exhibits ultrahigh tensile yield strength of 653.2 MPa with uniform elongation of 8.9%. χ is composed of alternating domains with different content of Mg and derives from disordering decomposition of metastable partially ordered δ'', as revealed by the first-principles calculations. This study subverts the understanding on the weak precipitation strengthening in Al-Mg alloys and their composites, and enlightens exploiting superior strength and ductility via ICNPs induced exotic precipitation strengthening.

纳米析出是铝合金及其复合材料获得高屈服强度和应变硬化能力的关键,而Al-Mg合金及其复合材料一般认为沉淀不会显著增强。该研究表明,在Al-Mg合金基复合材料中,颗粒内陶瓷纳米颗粒(ICNPs)附近形成了偏离常规沉淀顺序的相干成分调制沉淀χ,提供了~ 120 MPa的沉淀强化,并激活了ICNPs周围的早期塑性松弛。因此,含χ的碳纳米管增强Al-5Mg合金(wt.%)的抗拉屈服强度达到653.2 MPa,均匀伸长率达到8.9%。χ由不同Mg含量的交替结构域组成,由亚稳部分有序δ”的无序分解得到,由第一性原理计算得出。本研究颠覆了以往对Al-Mg合金及其复合材料弱析出强化的认识,为利用ICNPs诱导的异相析出强化获得优异的强度和延展性提供了启示。


Enhancing the bonding reliability of titanium alloy / CFRTP hybrid joint by directionally inducing high-density covalent bond and secondary interaction via functional diblock copolymer

Jianhui Su, Caiwang Tan, Xinbo Wang, Yifan Liu, Xueyan Zhang, Swee Leong Sing, Bo Chen, Yunhua Deng, Xiaoguo Song

doi:10.1016/j.compositesb.2024.112017

通过功能双嵌段共聚物定向诱导高密度共价键和二次相互作用,提高钛合金/ CFRTP复合接头的连接可靠性

The hybrid joint of titanium alloy (Ti-6Al-4V) / carbon fibers reinforced thermoplastic (CFRTP) has gained high interest from the industry due to lightweight. However, the bonding reliability of fabricated joints is relatively low due to the confined mechanical interlocking and weak interfacial chemical interactions, which limits its application for engineering. Herein, the novel functional poly glycidyl methacrylate-b-poly methacryloxy propyl trimethoxyl silane (PGMA-b-PMPTS) diblock copolymers were synthesized and introduced at the contact interface of Ti-6Al-4V / carbon fibers reinforced polyether-ether-ketone joints for enhancing the bonding reliability by directional induction of chemical interactions. Fourier-transform infrared spectroscopy (FT-IR) analysis and density function theory (DFT) simulation calculation proved that both the Si-O-Ti covalent bonds and secondary interactions were successfully induced directionally at the bonding interface. The tensile-shear strength and bending strength were thus significantly improved by 341 % to 40.17 MPa and 152 % to 238.53 MPa compared with that of 9.09 MPa and 94.53 MPa in pretreated case. The bonding reliability improved gradually with the increase of molecular weight and molecular weight ratios between functional groups of PGMA-b-PMPTS diblock copolymers. The adhesion ratio of resin-carbon fibers mixture on failure surface increased to 89.6 % after the modification with synthesized PGMA-b-PMPTS diblock copolymers, which further verified the feasibility of promoting bonding strength of Ti-6Al-4V / CFRTP by inducing the high-density interfacial interactions directionally. Current work exhibits a simple yet attractive interfacial modification strategy to achieve high-reliability hybrid joints between metal and thermoplastics.

钛合金(Ti-6Al-4V) /碳纤维增强热塑性塑料(CFRTP)复合接头因其轻量化而受到业界的高度关注。然而,由于有限的机械联锁和弱的界面化学相互作用,制造接头的结合可靠性较低,限制了其在工程上的应用。本文合成了新型功能聚甲基丙烯酸甘油酯-b-聚甲基丙烯酸氧基丙基三甲氧基硅烷(PGMA-b-PMPTS)二嵌段共聚物,并将其引入Ti-6Al-4V /碳纤维增强聚醚醚酮接头的接触界面,通过化学相互作用的定向诱导来提高键合的可靠性。傅里叶变换红外光谱(FT-IR)分析和密度泛函理论(DFT)模拟计算证明,Si-O-Ti共价键和二次相互作用都在键界面处成功定向诱导。抗剪强度和抗折强度分别比预处理后的9.09 MPa和94.53 MPa提高了341%和152%,分别达到40.17 MPa和238.53 MPa。随着PGMA-b-PMPTS二嵌段共聚物分子量和官能团间分子量比的增加,键合可靠性逐渐提高。合成的PGMA-b-PMPTS双嵌段共聚物改性后,树脂-碳纤维混合物在破坏表面的粘附率提高到89.6%,进一步验证了通过定向诱导高密度界面相互作用提高Ti-6Al-4V / CFRTP结合强度的可行性。目前的工作展示了一种简单而有吸引力的界面改性策略,以实现金属和热塑性塑料之间的高可靠性混合接头。


Exploring properties and hydration mechanisms in clinker-free cement formulated from steel industry solid waste using the extreme vertices method

Jie Liu, Jihui Zhao, Jiankai Liang

doi:10.1016/j.compositesb.2024.112018

利用极值顶点法研究钢铁工业固废配制的无熟料水泥的性能和水化机理

The development of clinker-free cementitious binders (CFCB) using industrial solid waste has attracted widespread attention due to their environmental and cost benefits. This study developed a CFCB using ground blast furnace slag (GBFS), steel slag (SS), and flue gas desulfurization gypsum (FGDG) as raw materials, utilizing an extreme vertex design method. The study systematically assessed the effects of each component on the CFCB’s properties, hydration behavior, and microstructure, and based on these findings, further elucidated its hydration mechanism using thermodynamic simulations. Results indicated that FGDG played a critical role in regulating the fluidity of the fresh pastes and the compressive strength of the hardened pastes. GBFS enhanced the development of compressive strength, while the high-activity aluminates in SS enhanced the early-stage compressive strength. Thermodynamic simulations and experimental results confirmed that reactive aluminates and sulfates led to the formation of expansive hydration products AFt and AFm, with volume expansion peaking around 10 d. As the hydration reaction progressed, the number of aluminates participating in the reaction gradually increased, promoting the formation of C-A-S-H, hydrogarnet, and hydrotalcite, as well as the transformation of AFt into AFm. Comprehensive analysis suggested that within the GBFS-SS-FGDG system, the proportion of FGDG should not be less than 10%, the content of GBFS should be controlled between 50-57.5%, and the content of SS should not exceed 37.5%. This study revealed the hydration mechanisms within the GBFS-SS-FGDG system, emphasizing the critical roles of each component.

利用工业固体废弃物开发无熟料胶凝粘结剂(CFCB)因其环境效益和成本效益而受到广泛关注。本研究采用极限顶点设计方法,以高炉磨渣(GBFS)、钢渣(SS)和烟气脱硫石膏(FGDG)为原料,开发了CFCB。本研究系统评估了各组分对CFCB性能、水化行为和微观结构的影响,并在此基础上通过热力学模拟进一步阐明了CFCB的水化机理。结果表明,FGDG对新鲜膏体的流动性和硬化膏体的抗压强度起着至关重要的调节作用。GBFS增强了抗压强度的发展,而SS中的高活性铝酸盐增强了早期抗压强度。热力学模拟和实验结果证实,活性铝酸盐和硫酸盐导致膨胀水化产物AFt和AFm的形成,体积膨胀在10 d左右达到峰值。随着水化反应的进行,参与反应的铝酸盐数量逐渐增加,促进了C-A-S-H、水榴石和水滑石的形成,并促进了AFt向AFm的转化。综合分析认为,在GBFS-SS-FGDG体系内,FGDG的比例不应低于10%,GBFS的含量应控制在50-57.5%之间,SS的含量不应超过37.5%。本研究揭示了GBFS-SS-FGDG体系的水化机制,强调了各组分的关键作用。


Composites Science and Technology

Porous conductive composite as piezoresistive sensors for smart safety helmet

Suhyeon Kim, Yeonhee Heo, Hyein Jung, Jeongmin Yoo, Jin-Tae Kim, Yoonseok Park

doi:10.1016/j.compscitech.2024.110985

 

多孔导电复合材料压阻式智能安全帽传感器

Safety helmets are essential protective gear for workers in hazardous environments, capable of reducing external impact forces by 90%. Proper helmet usage in any situation is crucial for ensuring maximum protection. In dangerous scenarios, if a helmet is dislodged or misaligned due to an external impact makes secondary impacts difficult to prevent. Quick adjustment to the correct position is essential. In this context, it is important to develop a smart helmet system capable of monitoring the spatial pressure distribution at the boundary between the helmet and head. Such a system could further provide guidance to users for proper wearing, enhancing safety in the work environment. This paper introduces the micro-porous elastomeric conductive composite as a soft, ultra-sensitive pressure sensor for low pressure regime (0-200 kPa). The sensor combines with a vibrotactile actuator and microcontroller, creating a haptic interface that responds to changes in pressure. Integrating haptic interfaces into safety helmets, smart helmets yield a system capable of real-time measurement of pressure between the helmets and head and delivers the wearing conditions to users. Detailed research into the materials, mechanical engineering aspects of this device, along with pilot perception tests, establishes the technical foundation and measurement capabilities of the proposed system.

安全帽是工人在危险环境中必不可少的防护装备,能够减少90%的外部冲击力。在任何情况下正确使用头盔对于确保最大程度的保护至关重要。在危险情况下,如果头盔因外部撞击而移位或错位,则难以防止二次撞击。迅速调整到正确的位置是必要的。在这种情况下,开发一种能够监测头盔与头部之间边界空间压力分布的智能头盔系统非常重要。该系统可以进一步指导用户正确佩戴,提高工作环境的安全性。本文介绍了一种用于低压(0- 200kpa)的柔性、超灵敏的微孔弹性导电复合材料压力传感器。该传感器结合了振动触觉致动器和微控制器,创建了一个响应压力变化的触觉界面。将触觉接口集成到安全帽中,智能头盔产生了一个能够实时测量头盔和头部之间压力的系统,并向用户提供佩戴条件。对该装置的材料、机械工程方面的详细研究,以及试点感知测试,建立了拟议系统的技术基础和测量能力。


来源:复合材料力学仿真Composites FEM
ACTMechanicalAdditiveSystemSTEPS振动断裂复合材料碰撞化学增材裂纹参数优化理论化机材料多尺度
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【新文速递】2024年10月23日复合材料SCI期刊最新文章

今日更新:Composite Structures 6 篇,Composites Part B: Engineering 2 篇,Composites Science and Technology 1 篇Composite StructuresEffective flexoelectric properties of inclusion-based composites based on strain gradient theory and homogenization techniqueLiangliang Chu, Fuqi Zhou, Guansuo Duidoi:10.1016/j.compstruct.2024.118665基于应变梯度理论和均质化技术的包体基复合材料有效挠电性能研究This study focuses on enhancing flexoelectricity in composites and develops a new micromechanical analytical framework to determine the effective electromechanical properties of inclusion-based flexoelectric composites within the context of SGE. Initially, we specialize in studying isotropic materials and derive the governing Navier equations for the problem. Subsequently, we streamline these differential equations by introducing a Laplacian-type gradient state variable, departing from higher-order gradient-enrichment treatments. The study employs Green’s functions and stress polarization tensors for spherical inhomogeneities, deriving homogenized material properties through volumetric averages of microscopic properties weighted by displacement localization operators. The analytical scheme’s relevance is validated against results from reference models and experimental data. Effective composite properties are evaluated using numerical methods, with an emphasis on assessing the impact of reinforcement on these properties. Our findings lay the foundation for developing a micromechanical method to predict the electromechanical behavior of composites. Specifically, we demonstrate the efficacy of our proposed theory by deriving effective flexoelectric properties of particulate composites.本研究的重点是增强复合材料的挠曲电性能,并开发了一种新的微力学分析框架,以确定在SGE背景下基于内含物的挠曲电复合材料的有效机电性能。最初,我们专注于研究各向同性材料,并推导出该问题的控制Navier方程。随后,我们通过引入拉普拉斯型梯度状态变量来简化这些微分方程,脱离高阶梯度富集处理。该研究采用格林函数和应力极化张量来描述球面非均质性,通过位移局部化算子加权微观特性的体积平均来推导均质材料特性。通过参考模型和实验数据验证了分析方案的相关性。使用数值方法评估有效复合材料的性能,重点是评估增强对这些性能的影响。我们的发现为开发一种微力学方法来预测复合材料的机电行为奠定了基础。具体来说,我们通过推导颗粒复合材料的有效挠曲电性能来证明我们提出的理论的有效性。An ultrathin ultralight electromagnetic absorber based on shortcut glass-coated amorphous magnetic Fiber/Salisbury-like screenHui Ji, Hong Xiao, Xinyi Ruan, Jianying Chen, Guoliang Dai, Ni Wangdoi:10.1016/j.compstruct.2024.118667基于快速玻璃涂层非晶磁性纤维/索尔兹伯里屏的超薄超轻电磁吸收器A structural design methodology is proposed for an ultrathin, ultralight, and absorption-adjustable electromagnetic absorber. The proposed absorber (SFSL) consists of an absorbing layer with shortcut glass-coated amorphous magnetic fiber and a substrate layer with transmitting material. This absorber features a Salisbury-like screen structure and incorporates multiple loss mechanisms. By investigating the influence of fiber distribution, length, content, and substrate layer thickness on absorption performance, it has been determined that the weight per square meter and thickness of a single-layer SFSL can be lowered within 50 g/m2 and 1.5 mm respectively. Furthermore, the absorption intensity and bandwidth can be adjusted by manipulating these parameters. The SFSL exhibits resonant behavior similar to that of a metamaterial absorber; however, SFSL with randomly distributed fibers demonstrates broader and stronger absorption characteristics in the frequency range from 2 to18 GHz. Additionally, the thicknesses of the substrate layer and surface covering affect the electromagnetic response characteristics. This work provides a simple strategy for constructing an ultrathin and ultralight composite to achieve efficient absorption of electromagnetic waves.提出了一种超薄、超轻、吸光度可调电磁吸收体的结构设计方法。所提出的吸波器(SFSL)由具有近距离玻璃涂层的非晶磁性光纤的吸收层和具有透射材料的基板层组成。这种吸收器具有索尔兹伯里式的屏幕结构,并结合了多种损耗机制。通过研究纤维分布、长度、含量和衬底层厚度对吸光性能的影响,确定单层SFSL的每平方米重量和厚度分别可以降低在50 g/m2和1.5 mm以内。此外,可以通过控制这些参数来调节吸收强度和带宽。SFSL具有类似于超材料吸收体的谐振特性;而光纤随机分布的SFSL在2 ~ 18 GHz频率范围内具有更宽、更强的吸收特性。此外,衬底层和表面覆盖层的厚度也会影响电磁响应特性。这项工作为构建超薄和超轻的复合材料提供了一种简单的策略,以实现电磁波的有效吸收。Machine learning for nano-level defect detection in aligned random carbon nanotubes-reinforced electrically conductive nanocompositeIskander S. Akmanov, Stepan V. Lomov, Mikhail Y. Spasennykh, Sergey G. Abaimovdoi:10.1016/j.compstruct.2024.118651定向随机碳纳米管增强导电纳米复合材料纳米级缺陷检测的机器学习Machine learning allows fast nano-scale defect detection in polymer-impregnated aligned carbon nanotube (CNT) nanocomposites. Digital twins were populated by TEM-validated geometry; considered defects were flat cracks and close-to-spherical voids. Finite-element analysis of piezoresistive response was conducted by embedment of CNT network into matrix. Identification of a defect by change in CNT network piezoresistivity was challenged by: (1) randomness of CNTs’ shapes and placement, ML training happened on random realisations; (2) high strength of CNTs leading to the preservation of conductive paths along CNTs and changes only in conductivities of tunnelling contacts. “Artificial approximation“ was introduced to economise computer time multi-fold: ML was trained on cases with artificially degraded tunnelling conductivities within the defect. Three ML models: XGBoost, fully connected, and convolution neural networks were employed. All models managed the task for near-spherical voids, but performed poorly for flat cracks, due to the limited number of tunnelling contacts in crack volume. When trained on the mixed set of voids and cracks, both neural networks demonstrated the ability to learn the difference and detected even cracks, while XGBoost was not up to the challenge. By metrics, the convolutional neural network demonstrated the highest accuracy of predictions.机器学习允许在聚合物浸渍排列碳纳米管(CNT)纳米复合材料中快速检测纳米级缺陷。数字双胞胎由tem验证的几何图形填充;考虑的缺陷是平坦的裂纹和接近球形的空隙。将碳纳米管网络嵌入到矩阵中,进行了压阻响应的有限元分析。通过碳纳米管网络压电阻率的变化来识别缺陷面临以下挑战:(1)碳纳米管形状和位置的随机性,机器学习训练发生在随机实现上;(2)碳纳米管的高强度使得沿碳纳米管的导电路径得以保留,只改变了隧道触点的电导率。引入“人工近似”以节省计算机时间:ML在缺陷内人为降低隧道电导率的情况下进行训练。使用了三种ML模型:XGBoost、全连接和卷积神经网络。所有模型都可以处理近球形空洞的任务,但由于裂纹体积中隧道接触的数量有限,对于扁平裂纹表现不佳。当在空洞和裂缝的混合集上进行训练时,两种神经网络都表现出了学习差异的能力,甚至可以检测到裂缝,而XGBoost无法应对挑战。通过度量,卷积神经网络显示出最高的预测准确性。Experimental investigation of the behavior of UHPCFST under repeated eccentric compressionChunlei Yu, Min Yu, Lihua Xu, Liu Sumei, Zewen Sun, Jianqiao Yedoi:10.1016/j.compstruct.2024.118661反复偏心压缩下UHPCFST性能的实验研究This paper investigates the mechanical behavior of ultra-high-performance concrete-filled steel tubes (UHPCFST) under repeated eccentric compression. A total of 30 UHPCFST specimens are designed, fabricated, and tested. The design variables include steel tube thickness, UHPC type, loading eccentricity and load pattern. Failure modes, force-axial shortening curves, section strain distributions, lateral deflection distributions, bearing capacity and stiffness are studied. Three failure modes, i.e., steel tube bulge, compressive crush and tensile crack of the UHPC infill are observed. Specimens with larger loading eccentricity and thinner steel tube are more likely to exhibit all the three modes. Subjected to eccentric loading, the compressive strength and stiffness of the UHPCFST increase significantly with the increase of steel tube thickness and UHPC strength. In the case of repeated loading, stiffness degradation is observed. Existing formulas for the N-M curve and the eccentric compressive capacity are evaluated against the test results. A formula for eccentric compressive stiffness is derived based on the parabolic function assumption. Additionally, an empirical model is introduced to describe the force-axial shortening relationship of the UHPCFST under repeated eccentric compression, which may be applied in practical design and analysis.本文研究了超高性能钢管混凝土(UHPCFST)在反复偏心受压作用下的力学性能。共设计、制作和测试了30个UHPCFST试件。设计变量包括钢管厚度、UHPC类型、加载偏心和加载方式。研究了破坏模式、力-轴缩短曲线、截面应变分布、侧向挠度分布、承载力和刚度。观察到钢管胀裂、压碎和拉裂三种破坏模式。加载偏心率越大、钢管越薄的试件更容易出现三种模态。在偏心载荷作用下,随着钢管厚度的增加和UHPC强度的增加,UHPCFST的抗压强度和刚度显著增加。在重复加载的情况下,观察到刚度退化。根据试验结果对现有的N-M曲线和偏心抗压能力公式进行了评价。基于抛物线函数假设,导出了偏心抗压刚度的计算公式。此外,还引入了一个经验模型来描述UHPCFST在反复偏心压缩下的力-轴向缩短关系,该模型可用于实际设计和分析。Mechanical model analysis of column-footing joints with combined socket-corrugated pipe connectionXiaolong Si, Yanchen Song, Guangda Zhang, Qiang Han, Xiuli Du, Bin Liudoi:10.1016/j.compstruct.2024.118666套筒-波纹管组合式柱-基础节点力学模型分析The socket connection method is widely used in precast column, particularly in seismic regions. However, reducing the socket-depth to lower costs may lead to shear failure in the socketed part of the columns. To address this issue and achieve cost objectives, a new approach combines shallow sockets with corrugated pipes for column-footing joints. Comparative tests were conducted to investigate failure in columns with socket-corrugated pipe connections (SCPC), shallow sockets (SSC), and cast-in-place (CIP). Furthermore, finite element models were employed to validate the experimental and simplified model results. The findings suggest potential shear failure in shallow socket connections, which can be mitigated by using the combined socket-corrugated pipe method that alters force transmission paths. As the axial load ratio increases, both the ultimate lateral load capacity of the specimen and the local stresses at the column base increase. In addition, the ultimate lateral load capacity of the column and the stress of the connection reinforcement are increased by increasing the strength of the longitudinal reinforcement, consequently amplifying the extent of joint area damage. Finally, a simplified strut-and-tie model of the SCPC, validated against numerical and experimental data, accurately represents force paths, ultimate lateral load capacity and failure modes in socket joints.嵌套连接法在预制柱中得到了广泛的应用,特别是在震区。然而,为了降低成本而减小嵌套深度可能会导致柱嵌套部分的剪切破坏。为了解决这一问题并实现成本目标,一种新的方法将浅插座与波纹管结合起来用于柱基础连接。进行了对比试验,研究了嵌套-波纹管连接(SCPC)、浅嵌套(SSC)和现浇(CIP)柱的破坏情况。采用有限元模型对实验结果和简化模型结果进行了验证。研究结果表明,浅套筒连接的潜在剪切破坏可以通过使用改变力传递路径的套筒-波纹管组合方法来减轻。随着轴向荷载比的增大,试件的极限侧载能力和柱底局部应力均增大。此外,纵筋强度的增加增加了柱的极限侧载能力和连接筋的应力,从而扩大了节点区域的破坏程度。最后,通过数值和实验数据验证了SCPC的简化杆扎模型,该模型准确地反映了承插节点的受力路径、极限侧向载荷能力和破坏模式。Composites Part B: EngineeringFibre waviness reduction in thermoplastic pultrusion by using DREF yarnsMaissaloun El-Jakl, Louis Laberge Lebeldoi:10.1016/j.compositesb.2024.111908用DREF纱降低热塑性拉挤中的纤维波浪度Non-reactive thermoplastic pultrusion impregnation issues are mitigated by using hybrid input materials. Co-wound (CW) and commingled yarns are an assembly of continuous polymer and reinforcement fibres. Continuous thermoplastic fibres have shown to induce waviness in the reinforcement fibres during pultrusion due to their shrinkage at high temperature. DREF yarns are composed of a core of continuous reinforcement fibres onto which discontinuous polymer fibres are applied using the friction spinning process. This study, based on the application of 3N and 0N tension on CW and DREF yarns, aimed to highlight the contribution of discontinuous polymer fibres on reducing reinforcement waviness in pultruded rods. CW yarns’ reaction to heating showed continuous polyethylene terephthalate (PET) fibres shrinkage resulting in wavy glass fibres (GF). Conversely, the GF in DREF yarns remained straight. Pultrusion experiments with yarn tension of 3N were done to alleviate the GF waviness. However, the porosity was rather high at 4.2% for CW rods and 2.3% for DREF rods. Pultrusion experiments without tension showed lower porosity of level of 2.9% for CW yarns and as low as 1.1% for DREF yarns. However, CT-scan image indicated GF waviness in CW rods. GF in DREF rods remained straight. The in-plane shear strength reached 119 MPa. Thermoplastic pultrusion using DREF yarns resulted in composites without reinforcement fibre waviness, lower porosity level and superior shear strength.非反应性热塑性拉挤浸渍问题通过使用混合输入材料得到缓解。共卷纱和混纺纱是由连续聚合物和增强纤维组成的纱线。连续热塑性纤维由于在高温下收缩,在拉挤过程中会引起增强纤维的波纹。DREF纱线由连续的增强纤维芯组成,在其上采用摩擦纺丝工艺应用不连续的聚合物纤维。本研究基于3N和0N张力在CW和DREF纱线上的应用,旨在突出不连续聚合物纤维在减少拉挤棒中的增强波浪度方面的贡献。连续化纤对加热的反应表明,聚酯纤维连续收缩,形成波浪状的玻璃纤维。相反,DREF纱线中的GF保持直。为了减轻纤维的波纹,进行了纱线张力为3N的拉挤实验。然而,CW棒的孔隙率相当高,为4.2%,DREF棒为2.3%。无张力拉挤实验表明,连续化纤纱线的孔隙率为2.9%,而DREF纱线的孔隙率为1.1%。然而,ct扫描图像显示在CW棒GF波状。在DREF棒中GF保持直。面内抗剪强度达到119 MPa。采用DREF纱线进行热塑性拉挤制备的复合材料无增强纤维波纹,孔隙率低,抗剪强度高。A novel model for predicting deformation of thermoplastic composites during heat-pressing processJiezheng Qiu, Zhonghai Xu, Chaocan Cai, Dianyu Chen, Shiging Huang, Chunxing Hu, Xiaodong Hedoi:10.1016/j.compositesb.2024.111912一种预测热塑性复合材料热压变形的新模型Carbon fiber/polyetheretherketone (CF/PEEK) thermoplastic composites are widely used in the aerospace industry due to their excellent mechanical properties and high-temperature resistance. However, the research on heat-pressing deformation and residual stress during high-temperature and high-pressure heat-pressing processes in CF/PEEK was relatively deficient. In this paper, a framework coupled with crystallization kinetics, micromechanics and thermodynamics was developed to predict the heat-pressing deformations of CF/PEEK and it was conducted by UMAT, DISP and UEXPAN subroutines. Moreover, the predictive model was verified by experiments effectively. Finally, we compared the difference in residual stress distributions between symmetric and asymmetric lay-ups and found that the melting temperature, thickness, angle and sequence of layers have a significant impact on the heat-pressing deformation. This work provided an effective tool for predicting heat-pressing deformations, which is great of significance in the manufacturing and application of CF/PEEK.碳纤维/聚醚醚酮(CF/PEEK)热塑性复合材料因其优异的机械性能和耐高温性能而广泛应用于航空航天工业。然而,对CF/PEEK高温高压热压过程中的热压变形和残余应力的研究相对缺乏。本文建立了一个结合结晶动力学、微观力学和热力学的框架,通过UMAT、DISP和UEXPAN子程序对CF/PEEK的热压变形进行了预测。通过实验验证了该预测模型的有效性。最后,对比了对称层和非对称层的残余应力分布差异,发现熔化温度、层厚、层角和层序对热压变形有显著影响。该工作为预测CF/PEEK的热压变形提供了有效的工具,对CF/PEEK的制造和应用具有重要意义。Composites Science and TechnologyVascular Bundle-Structured Polymeric Composites with Fire-safe, Self-detecting and Heat Warning Capabilities for Power Batteries Thermal ManagementXinyan An, Nvfan Tang, Yilin Liu, Shiqiang Song, Chaoyue Chen, Guohao Han, Weizhen Li, Yong Zhangdoi:10.1016/j.compscitech.2024.110921 用于动力电池热管理的具有火灾安全、自探测和热预警能力的维管束结构聚合物复合材料The trend of miniaturization and integration poses challenges to the thermal management of electronic devices, requiring high thermal conductivity and potential fire safety, etc. In this study, inspired by plant vascular structure, we developed a polymer composite with a vertical vascular bundle structure via a sacrificial template method and subsequent assembly of transition metal carbides/nitrides (MXene) nanosheets and phytic acid (PA) coordinated cobalt ions (Co2+) complex. The embedded MXene and PA@Co exhibit multilayer multiscale structural features, forming heat transfer channels and protective cells within the composite. The resultant composites possess high out-of-plane thermal conductivity (∼1.54 W‧m-1‧k-1) and excellent flame retardancy, including self-extinguishing, and significantly reduced heat and smoke release. Interestingly, the MXene vascular bundle structure imparts heat early warning capabilities and intelligent damage self-detection, suggesting an effective means of preventing early-stage fires and real-time monitoring of composite structural and functional integrity. Such biomimetic strategies enable new insights into the designing of multifunctional, intelligent polymer composites.小型化和集成化的趋势对电子器件的热管理提出了挑战,要求高导热性和潜在的火灾安全等。在本研究中,受植物维管束结构的启发,我们通过牺牲模板法和随后的过渡金属碳化物/氮化物(MXene)纳米片和植酸(PA)配位钴离子(Co2+)配合物的组装,开发了具有垂直维管束结构的聚合物复合材料。嵌入的MXene和PA@Co表现出多层多尺度的结构特征,在复合材料内部形成传热通道和保护细胞。合成的复合材料具有高的面外导热系数(约1.54 W·m·1·k-1)和优异的阻燃性,包括自熄性,并显着减少热量和烟雾释放。有趣的是,MXene维管束结构具有热预警能力和智能损伤自检测能力,是预防早期火灾和实时监测复合材料结构和功能完整性的有效手段。这种仿生策略为多功能智能聚合物复合材料的设计提供了新的见解。来源:复合材料力学仿真Composites FEM

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