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【新文速递】2024年2月19日复合材料SCI期刊最新文章

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今日更新:Composite Structures 2 篇,Composites Part A: Applied Science and Manufacturing 4 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 1 篇

Composite Structures

Influencing factors and sensitivity analysis for the fatigue of FRP wire based on the progressive fatigue damage model

Nani Bai, Hui Li, Chengming Lan, B.F. Spencer

doi:10.1016/j.compstruct.2024.117982

基于渐进疲劳损伤模型的玻璃钢线材疲劳影响因素及敏感性分析

FRP cables can experience degradation of their mechanical properties due to repetitive loading, resulting in increasing attention being devoted to their fatigue performance. This study aims to quantify the impact of the following four influencing factors on the fatigue behavior of FRP wire: (i) the applied maximum fatigue stress, (ii) interfacial shear strength, (iii) fiber volume fraction, and (iv) the Weibull shape parameter of the fiber fatigue strength coefficient. The recently developed progressive fatigue damage model (PFDM) is employed herein, and an adaptive block-by-block strategy is proposed to improve computational performance. The influences of the four factors on fatigue characteristics of FRP wire are illustrated using Monte Carlo simulation. Subsequently, a sensitivity analysis is performed for the fatigue behavior of FRP wire based on the linear regression approach, and Standardized Regression Coefficient is derived to rank the significance of the influencing factors. The following three indicators are selected to evaluate the sensitivities: (i) the fatigue life, (ii) the minimum normalized residual stiffness, and (iii) size of the critical damage cluster. Results show that the fatigue life and minimum normalized residual stiffness of FRP wire are most sensitive to the fiber volume fraction and Weibull shape parameter, respectively. Increasing fiber volume fraction can lead to longer fatigue life but results in more stiffness degradation before failure. A higher Weibull shape parameter leads to less stiffness degradation but results in a shorter fatigue life. Reducing the sensitivity of the FRP wire to cyclic degradation is best achieved by increasing the interfacial shear strength. This study can provide guidance for evaluation and optimization of the FRP wire fatigue behavior.

玻璃纤维增强塑料(FRP)缆线会因重复加载而导致机械性能下降,因此人们越来越关注其疲劳性能。本研究旨在量化以下四个影响因素对玻璃钢线缆疲劳行为的影响:(i) 施加的最大疲劳应力,(ii) 界面剪切强度,(iii) 纤维体积分数,以及 (iv) 纤维疲劳强度系数的 Weibull 形状参数。本文采用了最近开发的渐进疲劳损伤模型(PFDM),并提出了逐块自适应策略以提高计算性能。使用蒙特卡罗模拟说明了这四个因素对玻璃纤维增强塑料线材疲劳特性的影响。随后,基于线性回归方法对玻璃钢线材的疲劳行为进行了敏感性分析,并得出了标准化回归系数,对影响因素的重要性进行了排序。选择了以下三个指标来评估敏感性:(i) 疲劳寿命;(ii) 最小归一化残余刚度;(iii) 临界损伤群的大小。结果表明,玻璃钢丝的疲劳寿命和最小归一化残余刚度分别对纤维体积分数和 Weibull 形状参数最为敏感。纤维体积分数越大,疲劳寿命越长,但失效前的刚度退化也越严重。Weibull 形状参数越高,刚度退化越小,但疲劳寿命越短。降低玻璃钢丝对循环降解的敏感性最好通过提高界面剪切强度来实现。这项研究可为评估和优化玻璃钢丝疲劳行为提供指导。


Guided wave resonance identification of interface delamination in bimaterial composites

Mikhail V. Golub, Artem A. Eremin, Evgeny V. Glushkov, Natalia V. Glushkova

doi:10.1016/j.compstruct.2024.117983

双材料复合材料界面分层的导波共振识别

Laminate composites are widely used in industrial applications due to their high material strength and efficiency. In such materials, impact loads can cause internal delaminations at the bonding interfaces between sublayers, which further growth during operation could lead to structural failure. Guided wave based non-destructive testing allows detecting such hidden delamination, which manifests itself in the wavefield disturbance at the obstacle vicinity. However, their sizing requires sophisticated post-processing of the acquired wave signals. In our previous studies, a method for sizing an internal strip-like crack in a homogeneous elastic plate has been developed and experimentally approved. The method is based on the numerical evaluation of the scattering resonance frequencies depending on the crack size, and their comparison with the experimentally obtained ones. In the present paper, we extend this approach to the case of dissimilar-material laminates. Numerical simulation and laser Doppler vibrometry measurements were carried out for bi-layer samples composed of various combinations of glued steel, aluminium, and glass sublayers with artificial strip-like delamination. The results obtained confirm the possibility of damage width estimation using the values of scattering resonance frequencies extracted from the signals acquired at the sample surface.

层压复合材料因其材料强度高、效率高而被广泛应用于工业领域。在这类材料中,冲击载荷可能会在子层之间的粘合界面上造成内部分层,这种分层在运行过程中进一步扩大可能会导致结构失效。基于导波的无损检测可以检测这种隐藏的分层,其表现为障碍物附近的波场干扰。然而,要确定它们的大小,需要对获取的波信号进行复杂的后处理。在我们之前的研究中,已经开发出一种用于确定均质弹性板内部条状裂纹大小的方法,并通过了实验验证。该方法基于对取决于裂缝大小的散射共振频率进行数值评估,并将其与实验得到的频率进行比较。在本文中,我们将这种方法扩展到异种材料层压板的情况。我们对双层样品进行了数值模拟和激光多普勒测振仪测量,这些样品由人工条状分层的钢、铝和玻璃胶合层的不同组合组成。所得结果证实了利用从样品表面获取的信号中提取的散射共振频率值估算损伤宽度的可能性。


Composites Part A: Applied Science and Manufacturing

Recycled carbon fiber reinforced composites: Enhancing mechanical properties through co-functionalization of carbon nanotube-bonded microfibrillated cellulose

Mahyar Fazeli, Siddharth Jayaprakash, Hossein Baniasadi, Roozbeh Abidnejad, Juha Lipponen

doi:10.1016/j.compositesa.2024.108097

 

再生碳纤维增强复合材料:通过碳纳米管结合微纤化纤维素的共官能化提高机械性能

The imperative challenge of repurposing recycled carbon fiber (rCF) in composite structures, due to its cost-effectiveness and eco-friendly attributes, has spurred innovative research. This study introduces a scalable processing technique, integrating carbon nanotube (CNT)-bonded microfibrillated cellulose (MFC) onto randomly oriented rCF mats, focusing on enhancing mechanical properties. Employing electrophoretic deposition (EPD), rCF surfaces are effectively functionalized with CNT/MFC, probed through X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Modified fiber surfaces exhibit reduced contact angles, indicating improved wettability. Epoxy-based composites, fabricated via vacuum infusion, show up to 32% and 27% improvements in tensile and flexural strength. Dynamic mechanical analysis (DMA) confirms elevated storage modulus and energy dissipation capability. SEM analysis of fracture surfaces illustrates robust adhesion between coated fibers and the matrix, supporting the proposed approach's efficacy. This study unveils an innovative pathway to enhance recycled carbon fiber composite properties, extending their application potential in diverse engineering domains.

由于回收碳纤维(rCF)具有成本效益和生态友好的特性,在复合材料结构中对其进行再利用是一项迫切的挑战,这也推动了创新研究的发展。本研究介绍了一种可扩展的加工技术,将碳纳米管(CNT)键合的微纤化纤维素(MFC)集成到随机取向的 rCF 垫上,重点是提高机械性能。利用电泳沉积 (EPD),通过 X 射线光电子能谱 (XPS) 和扫描电子显微镜 (SEM) 对 rCF 表面进行了有效的 CNT/MFC 功能化。改性后的纤维表面接触角减小,表明润湿性得到改善。通过真空灌注制造的环氧基复合材料的拉伸强度和弯曲强度分别提高了 32% 和 27%。动态机械分析(DMA)证实了存储模量和能量耗散能力的提高。对断裂表面的扫描电子显微镜分析表明,涂覆纤维与基体之间的粘附力很强,证明了所建议方法的有效性。这项研究揭示了增强再生碳纤维复合材料性能的创新途径,从而拓展了其在不同工程领域的应用潜力。


Comprehensive assessment of hybrid GFRP-Graphite filler using modified complex Arcan fixture: Experimental and simulation approach

Daffa Alandro, Ariyana Dwiputra Nugraha, Iosif Azurra Maulana, Alvin Dio Nugroho, Wahyu Erlangga, Muhammad Akhsin Muflikhun

doi:10.1016/j.compositesa.2024.108094

 

使用改良的复杂 Arcan 夹具对 GFRP-石墨混合填料进行综合评估:实验和模拟方法

A detailed understanding of the interlaminar fracture, intralaminar fracture, and translaminar fracture progression of GFRP was studied using a complex Arcan fixture. A loading angle of 0o to 150o was successfully tested with detailed characteristics evaluated on 0o, 45o, and 90o. The different behaviors of the specimens were recorded in shear, tensile shear, and tensile stress. At these angles, the specimens reach 9.13, 36.00, and 51.64 MPa, while reaching the shear strain of 0.311, 0.153, and 0.046 με, respectively. FEM analysis was also incorporated to obtain the fracture behavior and stress distribution in the notch. Mises stress was 9.754 MPa, close to the average of 9.519 MPa from experiments. Adding graphite filler to the composite increases the composite's shear stress but reduced shear strain. 0.5% graphite filler became the optimal ratio by making the shear stress reach 16.94 MPa with a minimum decrease in shear strain with 0.293 με.

使用复杂的 Arcan 夹具研究了 GFRP 层间断裂、层内断裂和层间断裂的详细过程。成功测试了 0o 至 150o 的加载角度,并对 0o、45o 和 90o 的详细特征进行了评估。记录了试样在剪切、拉伸剪切和拉伸应力方面的不同行为。在这些角度下,试样的应力分别达到 9.13、36.00 和 51.64 兆帕,剪切应变分别为 0.311、0.153 和 0.046 με。此外,还通过有限元分析获得了缺口的断裂行为和应力分布。米塞斯应力为 9.754 兆帕,接近实验得出的平均值 9.519 兆帕。在复合材料中添加石墨填料会增加复合材料的剪切应力,但会降低剪切应变。0.5% 的石墨填料使剪切应力达到 16.94 兆帕,剪切应变的最小降幅为 0.293 με,成为最佳比例。


Enhancing Interlaminar Bonding Quality Estimation in Laser-Assisted Fiber Placement of CF/PEKK Composites: A Correction Factor Approach for Improved Prediction of Intimate Contact

Ali Barzegar, Sasan Karimi, Hatice S. Sas, Mehmet Yildiz

doi:10.1016/j.compositesa.2024.108095

在激光辅助纤维铺放 CF/PEKK 复合材料中提高层间粘合质量估计:改进亲密接触预测的修正系数方法

This study introduces an innovative Modified Mantell and Springer (MMS) model to more accurately assess degree of intimate contact with improved accuracy, which also significantly enhances the subsequent degree of healing estimation and enables the presentation of an improved degree of bonding. Process parameters such as placement speed and consolidation forces, and fiber orientation are identified as key determinants of bonding quality. Lower placement speeds and higher consolidation forces are linked to increased healing and intimate contact between layers, crucial for achieving desired degree of bonding. The MMS model proves effective in capturing the influence of fiber orientation, revealing that [0°/0°] orientation exhibits superior bonding strength. Validation through T-peel tests provides tangible evidence of the model's precision, aligning fracture surface observations with model predictions. This research contributes to a comprehensive understanding and prediction of composite bonding quality, offering valuable insights for optimizing manufacturing processes and enhancing the mechanical performance of composites manufactured with Laser-Assisted Fiber Placement (LAFP).

本研究引入了一种创新的修正曼特尔和斯普林格(MMS)模型,以更高的精度更准确地评估亲密接触程度,这也大大提高了后续愈合程度的估算,使粘合程度得到改善。贴片速度、固结力和纤维取向等工艺参数被认为是决定粘合质量的关键因素。较低的贴片速度和较高的固结力会增加愈合和层间的亲密接触,这对达到理想的粘合度至关重要。事实证明,MMS 模型能有效捕捉纤维取向的影响,揭示出[0°/0°]取向具有更高的粘合强度。通过 T 型剥离试验验证了模型的精确性,使断裂面观察结果与模型预测结果一致。这项研究有助于全面了解和预测复合材料的粘合质量,为优化制造工艺和提高使用激光辅助纤维铺放(LAFP)制造的复合材料的机械性能提供了宝贵的见解。


Multifunctional green composites based on plasma-activated and GO-coated dwarf palm fibers

Andrea Maio, Roberto Scaffaro

doi:10.1016/j.compositesa.2024.108096

基于等离子激活和 GO 涂层矮棕榈纤维的多功能绿色复合材料

In this work, we propose a green method for decorating natural fibers derived from dwarf palm waste with graphene oxide (GO) sheets. In detail, plasma-treatment was used to activate fiber surface for the subsequent GO-coating, which was performed in water. Poly(butylene adipate-co-terephthalate) (PBAT)-based composites incorporating 50% of either raw, plasma-modified or hybrid fibers were prepared by compression moulding and thoroughly analysed to investigate the processing-structure-properties relationships of these systems. The outcomes reveal that combining plasma treatment and GO coating enables fabricating green composites with significantly improved mechanical performance (stiffness and tensile strength increments of up to 500% and 300%, respectively) and electrical conductivity on the order of 10-6 S/m.

在这项工作中,我们提出了一种用氧化石墨烯(GO)薄片装饰从矮棕榈废料中提取的天然纤维的绿色方法。具体来说,我们使用等离子体处理来活化纤维表面,以便随后在水中进行 GO 涂层。通过压缩模塑法制备了含有 50% 未加工纤维、等离子体改性纤维或混合纤维的聚(己二酸丁二醇酯-对苯二甲酸酯)(PBAT)基复合材料,并对其进行了深入分析,以研究这些系统的加工-结构-性能关系。研究结果表明,将等离子处理与 GO 涂层相结合可制造出机械性能显著提高(刚度和拉伸强度分别提高了 500% 和 300%)、导电率达到 10-6 S/m 量级的绿色复合材料。


Composites Part B: Engineering

Achieving RCS reduction via scattering and absorption mechanisms using a chessboard structured composite

Qian Jiang, Huiming Fu, Jinming Duan, Lin Zheng, Jinming Jiang, Liwei Wu

doi:10.1016/j.compositesb.2024.111312

利用棋盘式结构复合材料的散射和吸收机制降低 RCS

Based on the concept of periodic structural unit, a chessboard structured composite composed of quartz fiber and carbon fiber is proposed in this study for reducing radar cross section (RCS). An automated manufacture technique – stitching was applied in the unit construction, showing the great potential on mass production and low cost. The design of RCS reduction adopts the cooperative mechanisms of absorption and scattering. The results show that the RCS reduction of chessboard structured composite is below −10dB in the range of 8.9–15.1GHz, and the peak value of the RCS reduction can reach −23dB. By simulating the different unit parameters of chessboard regions, the optimal parameters are obtained. Region 0 and region 1 present different energy distributions and a phase difference of 180° ± 78°, which is an important reason for the scattering mechanism of chessboard structured composite. To further explore the mechanisms of scattering and absorption, the electric field, magnetic field and power loss of the two regions at the absorption peak are simulated. According to the absorption energy distribution, it can be inferred that impedance matching plays an important role in the absorption mechanism. Moreover, the oblique incidence test and simulation prove the good angular stability of chessboard structured composite. The good mechanical properties of chessboard structured composite demonstrate the great potential of structure-function integration. Furthermore, the mass production capacity of the proposed composite gives the broad prospects in practical engineering application.

基于周期性结构单元的概念,本研究提出了一种由石英纤维和碳纤维组成的棋盘式结构复合材料,用于减小雷达截面(RCS)。在单元结构中应用了自动化制造技术--缝合,显示了大规模生产和低成本的巨大潜力。降低 RCS 的设计采用了吸收和散射的协同机制。结果表明,棋盘式结构复合材料在 8.9-15.1GHz 频率范围内的 RCS 降低率低于 -10dB,RCS 降低率的峰值可达 -23dB。通过模拟棋盘区域的不同单元参数,得到了最佳参数。区域 0 和区域 1 的能量分布不同,相位差为 180° ± 78°,这是棋盘结构复合材料散射机理的重要原因。为了进一步探讨散射和吸收机制,模拟了两个区域在吸收峰值处的电场、磁场和功率损耗。根据吸收能量分布,可以推断阻抗匹配在吸收机制中起着重要作用。此外,斜入射试验和模拟证明了棋盘结构复合材料具有良好的角度稳定性。棋盘结构复合材料良好的力学性能证明了结构-功能一体化的巨大潜力。此外,所提复合材料的大规模生产能力也为其在实际工程中的应用提供了广阔的前景。


Composites Science and Technology

Evaluating the loading rate dependency of mode I delamination for composite laminates at different temperatures

Junchao Cao, Bin Jiang, Zhouyi Li, Zhilong Dang, Chao Zhang

doi:10.1016/j.compscitech.2024.110505

 

评估不同温度下复合材料层压板模式 I 分层的加载速率相关性

This study presents an investigation on the influence of loading rate and temperature on mode I interlaminar fracture toughness of unidirectional composite laminates. An analytical model was developed to describe the temperature- and loading rate-dependent fracture toughness, and a loading rate coefficient m was defined to evaluate the rate dependency. Quasi-static and dynamic double cantilever beam (DCB) tests were conducted at various temperatures from −20 to 110 °C. A dual electromagnetic Hopkinson bar was employed to perform dynamic tests under loading rates of 15 and 24 m/s to achieve pure mode I delamination. The experimental results show that the fracture toughness exhibits an obvious positive loading rate sensitivity at all temperatures, whereas the loading rate coefficient m shows two different trends with temperature indicating different loading rate dependency. Fractography observations reveal an obvious transition in the dominant failure mechanism at low temperatures from fiber/matrix interface debonding under quasi-static conditions to brittle fracture of matrix under dynamic conditions. However, both the quasi-static and dynamic delamination surfaces exhibit multiple failure modes at high temperatures. It is reasonable to deduce that the effect of temperature and loading rate can be attributed to the nature of matrix, the bonding between fiber and matrix.

本研究探讨了加载速率和温度对单向复合材料层压板的模式 I 层间断裂韧性的影响。建立了一个分析模型来描述与温度和加载速率相关的断裂韧性,并定义了加载速率系数 m 来评估速率相关性。在 -20 至 110 °C 的不同温度下进行了准静态和动态双悬臂梁 (DCB) 试验。采用双电磁霍普金森杆在 15 和 24 m/s 的加载速率下进行动态测试,以实现纯 I 模式分层。实验结果表明,在所有温度下,断裂韧性都表现出明显的正加载速率敏感性,而加载速率系数 m 随温度的变化呈现出两种不同的趋势,表明了不同的加载速率依赖性。碎裂图观察结果表明,在低温条件下,主要的破坏机制从准静态条件下的纤维/基体界面脱粘明显过渡到动态条件下的基体脆性断裂。然而,准静态和动态脱层表面在高温下都表现出多种失效模式。由此可以合理地推断出,温度和加载速率的影响可归因于基体的性质、纤维与基体之间的粘合。



来源:复合材料力学仿真Composites FEM
ACTMechanicalSystemMAGNET疲劳断裂复合材料电子ADS裂纹电场BIM材料试验
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【新文速递】2024年2月22日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 1 篇,Journal of the Mechanics and Physics of Solids 1 篇,Mechanics of Materials 1 篇,Thin-Walled Structures 1 篇International Journal of Solids and StructuresModulating adhesion strength in multi-ferroic composite materials: Insights from adhesive contact with arbitrary profile indentersFa Wu, Shaobin Zhang, Chun Li, Xiangyu Lidoi:10.1016/j.ijsolstr.2024.112721调节多铁素体复合材料的粘附强度:从粘合剂与任意轮廓压头的接触中获得启示Adhesion control is a critical aspect of various applications, from industrial adhesion devices to the locomotion of insects on ceilings and walls. Multi-ferroic materials, which encompass mechanical, electrical, and magnetic properties, offer approaches for reversible adhesion control. This study presents a comprehensive theoretical framework for adhesive contact in multi-ferroic composite materials when subjected to axisymmetric rigid indenters with arbitrary profiles. We analytically derive the physical fields for various contact models, including Hertz contact, Johnson-Kendall-Roberts (JKR), and Maugis-Dugdale (MD) adhesive models. The obtained energy release rates indicate that the electric and magnetic potentials can modulate adhesion strength. The Griffith energy balance relation is employed to derive the indentation forces and penetration depths, which can be extended to a range of common indenters. Notably, the classical approximations fail when using small spherical indenters, but the study provides valid alternatives. The influence of amplitude and wavelength on contact behavior is explored, with greater effects observed for larger or smaller values. For cosine-shaped indenters, equivalence to flat-ended cylindrical punches is established under specific conditions. The study also reveals that the power indices for power-law-shaped indenters change the influence of electric and magnetic potentials on pull-off forces. These findings provide a theoretical fundament associated with the biomimetic and artificial adhesive systems and the modern testing techniques.从工业粘附装置到昆虫在天花板和墙壁上的运动,粘附控制是各种应用的一个重要方面。包含机械、电和磁特性的多铁素体材料为可逆粘附控制提供了方法。本研究提出了多铁素体复合材料在受到具有任意轮廓的轴对称刚性压头作用时发生粘附接触的综合理论框架。我们分析推导了各种接触模型的物理场,包括赫兹接触、约翰逊-肯德尔-罗伯茨(JKR)和毛吉斯-杜格代尔(MD)粘合模型。获得的能量释放率表明,电势和磁势可以调节粘附强度。格里菲斯能量平衡关系用于推导压痕力和穿透深度,可扩展到一系列常见的压头。值得注意的是,在使用小型球形压头时,经典近似方法失效,但这项研究提供了有效的替代方法。研究探讨了振幅和波长对接触行为的影响,观察到振幅和波长值越大或越小,影响越大。在特定条件下,余弦形压头等同于平头圆柱冲头。研究还发现,幂律形压头的功率指数会改变电势和磁势对拉拔力的影响。这些发现为仿生和人工粘合剂系统以及现代测试技术提供了理论基础。Journal of the Mechanics and Physics of SolidsOn rapid compaction of granular materials: Combining experiments with in-situ imaging and mesoscale modelingMohmad M. Thakur, Sohanjit Ghosh, Ryan C. Hurleydoi:10.1016/j.jmps.2024.105576关于颗粒材料的快速压实:将实验与现场成像和中尺度建模相结合Grain and pore kinematics are important features of the response of granular materials to impact loading and rapid compaction. These kinematics and the associated material-phase stresses control solidification processes in shock-driven manufacturing and ignition in energetic materials. Diagnostics used in traditional gas-gun experiments cannot resolve spatially-heterogeneous grain and pore kinematics during granular compaction. Similarly, continuum models of the granular compaction process do not account for this spatial heterogeneity, making predictions of solidification or ignition challenging. Here, we propose a method of accessing spatially-heterogeneous grain and pore behaviors during rapid compaction which involves x-ray tomography, in-situ x-ray phase contrast imaging, and mesoscale numerical modeling. We use this method to study heterogeneous grain and pore kinematics and local stresses in a ductile aluminum powder impacted at velocities up to 800 m/s. We first validate the mesoscale model by comparing its predictions with x-ray measurements from an impact experiment on a sample that was used to generate a numerical microstructure. We then quantify the evolution of variables such as 3D pore sizes and local stresses. We comment on the role of microstructure on the granular material’s response and the sensitivity of the material response to changes in structure, impact velocity, and sample size.颗粒和孔隙运动学是颗粒材料对冲击加载和快速压实反应的重要特征。这些运动学和相关的材料相应力控制着冲击驱动制造和高能材料点火过程中的凝固过程。传统气 枪实验中使用的诊断方法无法解析颗粒压实过程中的空间均质颗粒和孔隙运动学。同样,粒状压实过程的连续模型也无法解释这种空间异质性,因此对凝固或点火的预测具有挑战性。在这里,我们提出了一种在快速压实过程中获取空间异质性颗粒和孔隙行为的方法,其中包括 X 射线断层扫描、原位 X 射线相衬成像和中尺度数值建模。我们利用这种方法研究了以高达 800 米/秒的速度冲击的韧性铝粉中的异质晶粒和孔隙运动学以及局部应力。首先,我们将中尺度模型的预测结果与用于生成数值微观结构的样品冲击实验的 X 射线测量结果进行比较,从而验证中尺度模型。然后,我们对三维孔隙大小和局部应力等变量的演变进行了量化。我们评论了微观结构对颗粒材料响应的作用,以及材料响应对结构、冲击速度和样品尺寸变化的敏感性。Mechanics of MaterialsGeometric effects on impact mitigation in architected auxetic metamaterialsT. Gärtner, S.J. van den Boom, J. Weerheijm, L.J. Sluysdoi:10.1016/j.mechmat.2024.104952 建筑辅助超材料对减缓冲击的几何效应Lightweight materials used for impact mitigation must be able to resist impact and absorb the maximum amount of energy from the impactor. Auxetic materials have the potential to achieve high resistance by drawing material into the impact zone and providing higher indentation and shear resistance. However, these materials must be artificially designed, and the large deformation dynamic effects of the created structures must be taken into consideration when deciding on a protection concept. Despite their promise, little attention has been given to understanding the working mechanisms of high-rate and finite deformation effects of architected auxetic lattice structures. This study compares the static and dynamic elastic properties of different auxetic structures with a honeycomb structure, a typical non-auxetic lattice, at equivalent mass and stiffness levels. In this study, we limit the investigation to elastic material behavior and do not consider contact between the beams of the lattices. It is demonstrated that the equivalent static and dynamic properties of individual lattices at an undeformed state are insufficient to explain the variations observed in impact situations. In particular, the initial Poisson’s ratio does not determine the ability of a structure to resist impact. To gain a thorough comprehension of the overall behavior of these structures during localized, high rate compression, the evolution of the elastic tangent properties under compression and shear deformation was monitored, leading to a more profound understanding. Observations made in one configuration of stiffness and mass are replicated and analyzed in related configurations.用于减缓撞击的轻质材料必须能够抵抗撞击并最大限度地吸收来自撞击器的能量。辅助材料有可能通过将材料吸入撞击区并提供较高的抗压和抗剪切能力来实现较高的抗冲击性。不过,这些材料必须经过人工设计,而且在决定保护概念时,必须考虑到所创建结构的大变形动态效应。尽管这些材料大有可为,但人们却很少注意了解建筑辅助晶格结构的高速率和有限变形效应的工作机制。本研究比较了不同辅助结构与蜂窝结构(一种典型的非辅助晶格)在同等质量和刚度水平下的静态和动态弹性特性。在本研究中,我们只研究弹性材料行为,不考虑晶格梁之间的接触。研究表明,单个晶格在未变形状态下的等效静态和动态特性不足以解释在冲击情况下观察到的变化。特别是,初始泊松比并不能决定结构的抗冲击能力。为了全面了解这些结构在局部高速压缩过程中的整体行为,我们对压缩和剪切变形下弹性正切特性的演变进行了监测,从而获得了更深刻的理解。对一种刚度和质量配置的观察结果在相关配置中进行了复 制和分析。Thin-Walled StructuresMachine learning assisted prediction and analysis of in-plane elastic modulus of hybrid hierarchical square honeycombsJian Yang, Dingkun Yang, Yong Tao, Jun Shidoi:10.1016/j.tws.2024.111736 机器学习辅助预测和分析混合分层方形蜂窝的面内弹性模量In this study, experimental, finite element (FE) simulation, machine learning (ML), and theoretical techniques are employed to investigate the in-plane elastic modulus (E_HHSH) of hybrid hierarchical square honeycombs (HHSHs). First, HHSHs with different configurations were fabricated using a 3D printer, and in-plane quasi-static compression tests were conducted on them. Then, 234 FE models are simulated to determine the E_HHSH of HHSHs with various configurations, and the results are used to train 11 ML models. Comparative analysis demonstrates that the Extreme Gradient Boosting (XGBoost) model has the best predictive capability. Moreover, a modified theory for E_HHSH is established based on the XGBoost model and existing theory, and its exceptional predictive capability is verified by comparing with experimental, FE, and existing theoretical results. Finally, the upper and lower bounds of E_HHSH are determined by the modified theory, and the Shapley Additive Explanation (SHAP) method is used to identify the importance of different geometric parameters on tailoring E_HHSH. The combination of theoretical and ML techniques provides a promising approach for developing a robust prediction model of material properties.本研究采用实验、有限元(FE)模拟、机器学习(ML)和理论技术来研究混合分层方形蜂窝(HHSHs)的面内弹性模量(E_HHSH)。首先,使用 3D 打印机制作了不同结构的 HHSH,并对其进行了平面准静态压缩试验。然后,对 234 个有限元模型进行仿真,以确定具有不同配置的 HHSH 的 E_HHSH,并将结果用于训练 11 个 ML 模型。对比分析表明,极端梯度提升(XGBoost)模型具有最佳预测能力。此外,在 XGBoost 模型和现有理论的基础上,建立了 E_HHSH 的修正理论,并通过与实验、FE 和现有理论结果的比较,验证了其卓越的预测能力。最后,通过修正理论确定了 E_HHSH 的上下限,并利用夏普利加法解释(SHAP)方法确定了不同几何参数对定制 E_HHSH 的重要性。理论与 ML 技术的结合为开发稳健的材料特性预测模型提供了一种可行的方法。来源:复合材料力学仿真Composites FEM

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