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【新文速递】2024年3月8日固体力学SCI期刊最新文章

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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 3 篇

International Journal of Solids and Structures

Design and study of novel Nested auxetic lattices with tunable and enhanced in-plane elastic properties

Antu Acharya, Anirvan DasGupta, Atul Jain

doi:10.1016/j.ijsolstr.2024.112749

设计和研究具有可调和增强面内弹性特性的新型嵌套辅助晶格

Auxetic lattices are interesting engineering materials due to Negative Poisson’s Ratio (NPR). However, auxetic lattices usually have extremely low stiffness and exhibit high anisotropy (E1/E2>>1), severely limiting their application in high-loading environments. Attempts at increasing the stiffness of lattices typically lead to a decrease in auxeticity and an increase in anisotropy. In the current study, using novel nesting strategies, modified Sinusoidal Re-entrant Honeycomb (SRH) microstructures are developed to enhance stiffness, retain the auxeticity and introduce nearly isotropic characteristics (E1/E2 ∼ 1). Different Nested n-type (n = 0, 1,2, 3 and 4) microstructures have been studied. Translation studies involving 90° and 0° oriented lattices are undertaken to find the effect of these nesting along different lengths and combinations leading to enhanced stiffness with minor loss in auxeticity. The possibility of attaining a stiffness at least 1500 % greater than the empty lattices, while retaining significant auxeticity (Poisson’s ratio < -1) has been showcased. The proposed approach can also lead to the development of lattices that exhibit nearly isotropic characteristics. The proposed approach can be realized using the state-of-art capabilities of modern 3D printers. The proposed methods and modifications are simple yet very substantial in terms of property enhancement and can be extended to almost all types of lattices.

由于具有负泊松比(NPR),磁性晶格是一种有趣的工程材料。然而,辅助晶格通常具有极低的刚度和较高的各向异性(E1/E2>>1),严重限制了其在高负载环境中的应用。提高晶格刚度的尝试通常会导致辅助性降低和各向异性增加。本研究采用新颖的嵌套策略,开发出改进的正弦再入蜂窝(SRH)微结构,以提高刚度、保留辅助性并引入近乎各向同性的特性(E1/E2 ∼ 1)。对不同的嵌套 n 型(n = 0、1、2、3 和 4)微结构进行了研究。涉及 90° 和 0° 方向晶格的平移研究旨在发现这些嵌套沿不同长度和组合的影响,从而在提高刚度的同时略微降低辅助性。结果表明,在保持显著辅助eticity(泊松比<-1)的同时,刚度比空网格至少高出 1500%。所提出的方法还可以开发出具有近乎各向同性特征的晶格。所提出的方法可以利用现代三维打印机的先进功能来实现。所提出的方法和修改虽然简单,但却能极大地提高性能,并可扩展到几乎所有类型的晶格。


Journal of the Mechanics and Physics of Solids

Fully optimized second-order estimates for the macroscopic behavior and field statistics of particle-reinforced viscoplastic composites

Christoph Kammer, Pedro Ponte Castañeda

doi:10.1016/j.jmps.2024.105598

对颗粒增强粘塑性复合材料的宏观行为和场统计进行全面优化的二阶估算

This paper is concerned with the characterization of the macroscopic behavior and statistics for the distribution of the stress and strain-rate fields in composites consisting of random and isotropic suspensions of rigid spherical particles in a power-law viscoplastic material. For this purpose, use is made of the Fully Optimized Second-Order (FOSO) homogenization method (Ponte Castañeda, 2016) in combination with recently developed estimates (Kammer and Ponte Castañeda, 2022) for the macroscopic properties of the associated ‘linear comparison composite’ (LCC). Special attention is devoted to the method’s ability to account for the dependence of the homogenized properties of the nonlinear composite on the Lode angle (third invariant) of the applied loading. It is found that, while, for large particle volume fractions c, the effective flow stress is only weakly dependent on the Lode angle, for dilute volume fractions, the dependence on the Lode angle becomes more pronounced. In the ideally plastic limit, as c tends to zero, the effective yield stress is shown to depend linearly on c for axisymmetric shear, while this dependence becomes weaker with a non-analytic leading-order correction of O(c/ln c) for pure shear loading. This strong dependence on the Lode angle at dilute concentrations is shown to be due to significant differences in the local deformation patterns, which become strongly anisotropic and localize for pure shear conditions, but do not for axisymmetric shear. In turn, the FOSO homogenization method is able to capture the statistical features of these different deformation patterns by providing consistent estimates for the covariance tensor of the strain-rate field fluctuations in the matrix phase, which tend to become more strongly anisotropic for the pure shear case. As c increases, the shear bands are deflected by the randomly dispersed spheres leading to a more isotropic distribution of the stress and strain-rate fields, which is consistent with a weaker Lode angle effect. The estimates can also capture the effect of strong particle interactions, including the existence of a rigidity threshold where the macroscopic flow stress and field fluctuations blow up.

本文关注的是由幂律粘塑性材料中刚性球形颗粒的随机和各向同性悬浮液组成的复合材料中应力场和应变率场分布的宏观行为和统计特征。为此,我们采用了完全优化二阶(FOSO)均质化方法(Ponte Castañeda, 2016),并结合最近开发的相关 "线性比较复合材料"(LCC)宏观特性的估计值(Kammer 和 Ponte Castañeda, 2022)。特别关注的是该方法能否解释非线性复合材料的均质化特性与所施加载荷的洛德角(第三不变量)之间的关系。研究发现,当颗粒体积分数 c 较大时,有效流动应力与洛德角的关系较弱,而当颗粒体积分数较小时,与洛德角的关系则更为明显。在理想塑性极限中,当 c 趋近于零时,对于轴对称剪切,有效屈服应力与 c 呈线性关系,而对于纯剪切加载,这种依赖性在 O(c/ln c)的非解析前阶修正下变得更弱。稀释浓度下对 Lode 角的这种强烈依赖性被证明是由于局部变形模式的显著差异造成的,在纯剪切条件下,局部变形变得强烈各向异性,而在轴对称剪切条件下则不然。反过来,FOSO 均质化方法能够捕捉到这些不同变形模式的统计特征,为矩阵相中应变率场波动的协方差张量提供一致的估计值,而在纯剪切情况下,这些应变率场波动往往变得更加强烈各向异性。随着 c 的增大,剪切带被随机分散的球体偏转,导致应力场和应变率场的分布更加各向同性,这与较弱的洛德角效应相一致。估计值还能捕捉到强粒子相互作用的影响,包括存在一个刚性阈值,在该阈值下宏观流动应力和场波动会爆发。


Mechanics of Materials

Explicating tensile response of AA6061-T6 sheet post single point incremental forming: Two camera-DIC strain measurement and texture analysis

Mohit Sharma, Anirban Bhattacharya, Surajit Kumar Paul

doi:10.1016/j.mechmat.2024.104963

解释单点增量成形后 AA6061-T6 板材的拉伸响应:双摄像头-DIC 应变测量和纹理分析

Incremental sheet forming (ISF) produces 3D components imposing localized deformation by spherical-ended tool moving on a predefined path without requiring component-specific die/punch. The formability achieved in ISF is much higher than the conventional sheet forming processes; however, the deformation imposed during ISF alters the mechanical properties of the component. The present work investigates the tensile behavior and strain localization during the uniaxial tensile test of the AA6061-T6 component after single point incremental forming (SPIF). The influence of incremental depth (Δz) and tool diameter (dt) on the tensile response and strain localization is illustrated by a digital image correlation setup with two cameras. The tensile strength of SPIF components increases with Δz and mildly decreases with dt. The changes in scallop heights/undulations formed due to tool movement at higher Δz and dt influence the localized strain accumulation. Regions of localized strain are more when Δz is high, but strain accumulation is more even with an increase in dt. Texture analysis showed increased dislocation density due to the strain hardening after SPIF. The presence of brass {011}<211>, copper {112}<111>, and S {123}<634> texture indicates the plane-strain deformation in the wall region of the component formed by SPIF.

增量式板材成形(ISF)通过在预定路径上移动的球形端部工具施加局部变形来生产三维部件,而无需特定的部件模具/冲头。ISF 所实现的成型性远远高于传统的板材成型工艺;然而,ISF 过程中施加的变形会改变部件的机械性能。本研究对单点增量成形(SPIF)后的 AA6061-T6 部件进行单轴拉伸试验时的拉伸行为和应变定位进行了研究。通过使用两台相机的数字图像相关装置,说明了增量深度(Δz)和工具直径(dt)对拉伸响应和应变定位的影响。SPIF 组件的拉伸强度随 Δz 增大,随 dt 减小。在较高的 Δz 和 dt 条件下,由于工具移动而形成的扇贝高度/凹陷的变化会影响局部应变的累积。当 Δz 较高时,局部应变区域较多,但随着 dt 的增加,应变累积更为均匀。纹理分析表明,由于 SPIF 后的应变硬化,位错密度增加。黄铜{011}<211>、铜{112}<111>和S{123}<634>纹理的存在表明 SPIF 所形成的部件壁区存在平面应变变形。


Thin-Walled Structures

Linear active disturbance rejection control algorithm for active vibration control of piezo-actuated beams: theoretical and experimental studies

Xian Guang Sun, Wei Chao Chi, Yan Qing Wang

doi:10.1016/j.tws.2024.111782

压动梁主动振动控制的线性主动干扰抑制控制算法:理论与实验研究

The active vibration control (AVC) of lightweight thin-walled structures on spacecraft has been a proven solution for vibration suppression. In this study, a linear active disturbance rejection control (LADRC) algorithm is presented for vibration suppression of piezo-actuated beams. Firstly, the governing equation of a piezo-actuated beam is obtained by using the Euler-Bernoulli beam theory and the Lagrange equation. The LADRC algorithm is designed for the piezo-actuated beam based on the governing equation. Then, the accuracy of the piezo-actuated beam model is confirmed by comparison with ANSYS and experiments. Finally, numerical simulations and experiments are carried out on the active vibration suppression of the piezo-actuated beam under the fixed harmonic excitation, variable harmonic excitation, and fixed harmonic excitation with measuring noise, respectively. The results show that the LADRC algorithm has an excellent control effect on structural vibration suppression, strong adaptability to various external excitations, and anti-noise ability.

航天器轻质薄壁结构的主动振动控制(AVC)是一种行之有效的振动抑制解决方案。本研究针对压动梁的振动抑制提出了一种线性主动干扰抑制控制(LADRC)算法。首先,利用欧拉-伯努利梁理论和拉格朗日方程得到压动梁的支配方程。根据支配方程设计了压动梁的 LADRC 算法。然后,通过与 ANSYS 和实验的对比,确认了压动梁模型的准确性。最后,分别对固定谐波激励、可变谐波激励和带测量噪声的固定谐波激励下压动梁的主动振动抑制进行了数值模拟和实验。结果表明,LADRC 算法对结构振动抑制具有良好的控制效果,对各种外部激励具有较强的适应性和抗噪声能力。


Vibration frequency and mode localization characteristics of strain gradient variable-thickness microplates

Tao Deng, Bo Zhang, Juan Liu, Huoming Shen, Xu Zhang

doi:10.1016/j.tws.2024.111779

应变梯度可变厚度微孔板的振动频率和模式定位特性

Based on the modified strain gradient theory and Kirchhoff-Love assumptions, a free vibration model is established for variable-thickness microplates with three material length scale parameters, and the corresponding Euler-Lagrange equation is derived. Keeping the microplate volume constant, three kinds of thickness variations along the X-direction are considered: linear, parabolic, and cubic variations. Further, a C2-type four-node 36-degree-of-freedom variable-thickness differential quadrature finite element is developed to solve the resulting variable-coefficient boundary value problem by combining the Gauss-Lobatto and differential quadrature rules. Galerkin approximate solution for fully simply supported microplates is provided as a benchmark for numerical method verification. The convergence and accuracy of the model are verified through several examples. Finally, the vibration frequencies of the microplates under different thickness variation types, taper ratios, thickness ratios, material length scale parameters, and boundary conditions are examined through parametric analysis. Also, the influence of each factor on the mode localization of the microplates is quantitatively characterized by the modal assurance criterion (MAC) for the first time. The numerical results show that the thickness variation has a minor effect on the vibration frequency but a significant influence on the mode shape when the volume of the microplate is constant. The strain gradient, taper ratio, and discontinuous boundary have a remarkable effect on the distribution of higher-order mode shape contour lines and the regions where vibration localization occurs.

基于修正的应变梯度理论和基尔霍夫-洛夫假设,建立了具有三个材料长度尺度参数的变厚度微板自由振动模型,并推导出相应的欧拉-拉格朗日方程。在保持微孔板体积不变的情况下,考虑了三种沿 X 方向的厚度变化:线性变化、抛物线变化和三次方变化。此外,一个 C2 型四节点 36 自由度可变厚度微分正交有限元,通过结合高斯-洛巴托规则和微分正交规则来解决由此产生的可变系数边界值问题。提供了完全简单支撑微板的 Galerkin 近似解作为数值方法验证的基准。通过几个实例验证了模型的收敛性和准确性。最后,通过参数分析研究了不同厚度变化类型、锥度比、厚度比、材料长度尺度参数和边界条件下微板的振动频率。同时,通过模态保证准则(MAC)首次定量分析了各因素对微板模态定位的影响。数值结果表明,当微孔板的体积不变时,厚度变化对振动频率的影响较小,但对模态振型的影响很大。应变梯度、锥度比和不连续边界对高阶模态振型轮廓线的分布和发生振动局部化的区域有显著影响。


Enhancing the reliability of laser welded-brazed aluminum/stainless steel joints via laser-chemical hybrid surface texturing

Haoyue Li, Hongbo Xia, Liqun Li, Longqiu Li, Xuan Su, Jin Peng, Yunwu Ma, Caiwang Tan, Xiaoguo Song, Tao Wu

doi:10.1016/j.tws.2024.111780

通过激光-化学混合表面纹理处理提高激光焊接-钎焊铝/不锈钢接头的可靠性

Surface microtexture is a promising technique for enhancing the quality of heterogeneous joints. This study developed a novel surface texturing method to improve the reliability of laser welded-brazed aluminum/stainless steel joints. The method combined laser etching and chemical etching to create high-quality multi-scale surfaces with large grooves and small wrinkles. The designed microtexture promoted atomic transfer and induced the generation of nanoscale η-Fe2(Al,Si)5 phases during the welding-brazing process. It reduced the spreading activation energy along the groove direction, which enlarged the joining area. It also optimized the strain-stress distribution to enhance the deformation tolerance of the bonding interface throughout the structural strengthening mechanism. Through the synergistic regulation, the joint achieved a maximum line load of 495.9 N/mm, which was 61% higher than the untextured joint of 307.5 N/mm. The joint performance reached 95% of the Al/Al lap joint (519.3 N/mm) with the same welding parameters. This study provided new insights into the high-quality joining of aluminum/steel systems or other heterogeneous materials.

表面微纹理是提高异质接头质量的一种有前途的技术。本研究开发了一种新型表面纹理处理方法,以提高激光焊接-钎焊铝/不锈钢接头的可靠性。该方法结合了激光蚀刻和化学蚀刻技术,可制造出具有大凹槽和小皱纹的高质量多尺度表面。设计的微纹理促进了原子转移,并在焊接-钎焊过程中诱导生成了纳米级的 η-Fe2(Al,Si)5 相。它降低了沿沟槽方向的扩展活化能,从而扩大了接合面积。它还优化了应变应力分布,在整个结构强化机制中提高了结合界面的变形容限。通过协同调节,接头的最大线荷载达到了 495.9 牛顿/毫米,比无纹理接头的 307.5 牛顿/毫米高出 61%。在相同的焊接参数下,接头性能达到了铝/铝搭接接头(519.3 N/mm)的 95%。这项研究为铝/钢系统或其他异质材料的高质量焊接提供了新的见解。



来源:复合材料力学仿真Composites FEM
ACTMechanicalSystemDeform振动复合材料非线性化学航天CONVERGE焊接理论化机材料多尺度控制
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首次发布时间:2024-11-06
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【新文速递】2024年2月24日复合材料SCI期刊最新文章

今日更新:Composite Structures 3 篇,Composites Part A: Applied Science and Manufacturing 2 篇,Composites Part B: Engineering 3 篇,Composites Science and Technology 1 篇Composite StructuresSmall-dependent nonlinear analysis of functionally graded triply periodic minimal surface nanoplatesP. Phung-Van, P.T. Hung, Chien H. Thaidoi:10.1016/j.compstruct.2024.117986功能分级三周期最小表面纳米板的小依赖非线性分析This paper introduces an effective and simple approach to analyze functionally graded triply periodic minimal surface (FG-TPMS) nanoplates, taking advantage of a novel nonlocal strain gradient nonlinear analysis. TPMS has recently gained attention as an extraordinary solution for constructing structures, drawing inspiration from natural architectures. It offers remarkable features, including high interconnectivity porous architectures, smooth surfaces, and the ability to achieve mathematically controllable geometry features. However, the extensive potential and benefits of TPMS structures have not been fully explored in current research. Hence, this study aims to address this limitation and unlock new possibilities for FG-TPMS nanoplates. Three patterns of FG-TPMS nanoplates, namely Primitive (P), Gyroid (G), and I-gragh and Wrapped Package-graph (IWP), are utilized in this investigation. The proposed model effectively incorporates the nonlocal,strain gradient and nonlinear effects into nanoplate structures. It enables a comprehensive understanding of the mechanisms responsible for both reducing and enhancing stiffness in the nanoplate by fine-tuning the nonlocal and strain gradient parameters. This research offers promising prospects for future design and optimization, providing a robust approach to address the intricate nonlinear behavior observed in FG-TPMS nanoplates.本文利用新颖的非局部应变梯度非线性分析方法,介绍了一种分析功能分级三周期最小表面(FG-TPMS)纳米板的有效而简单的方法。最近,TPMS 从自然建筑中汲取灵感,作为一种构造结构的非凡解决方案而备受关注。它具有显著的特点,包括高互联性多孔结构、光滑表面以及实现数学可控几何特征的能力。然而,目前的研究尚未充分挖掘 TPMS 结构的广泛潜力和优势。因此,本研究旨在解决这一局限性,为 FG-TPMS 纳米板开启新的可能性。本研究采用了三种 FG-TPMS 纳米板的模式,即原始(P)、陀螺(G)和 I-gragh and Wrapped Package-graph (IWP)。所提出的模型有效地将非局部、应变梯度和非线性效应纳入了纳米板结构。通过微调非局部和应变梯度参数,该模型能够全面了解降低和增强纳米板刚度的机制。这项研究为未来的设计和优化提供了广阔的前景,为解决在 FG-TPMS 纳米板中观察到的错综复杂的非线性行为提供了可靠的方法。Fiber-level modeling of 3D braided preforms using virtual braiding methodXi Liao, Yanan Jiao, Junbo Xie, Li Chendoi:10.1016/j.compstruct.2024.117988利用虚拟编织法进行三维编织预成型的纤维级建模High fidelity geometry models of the preforms are essential in mechanical property analysis for composite materials. The paper presents a virtual braiding method to generate digital material twins of 3D braided preforms. The four-step 3D braiding process is simulated based on the concept of virtual fiber and according to the rule of yarn movement. Fiber-level models of the preform are constructed which display the micro-scale architectures explicitly, including compressive deformations of yarn cross-sections and variations of yarn paths. The Micro-CT test is employed to investigate the internal fiber structures of 3D braided preform and quantitatively verify the accuracy of the proposed modeling method. Influence of the braiding parameters, such as yarn tension and arrangement angle in the initial state on geometric parameters of the preform is then investigated.预型件的高保真几何模型对于复合材料的机械性能分析至关重要。本文介绍了一种虚拟编织方法,用于生成三维编织预型件的数字材料双胞胎。根据虚拟纤维的概念和纱线运动规律,模拟了四步三维编织过程。构建的预型件纤维级模型可清晰显示微尺度结构,包括纱线横截面的压缩变形和纱线路径的变化。利用 Micro-CT 测试研究了三维编织预成型的内部纤维结构,并定量验证了所提出的建模方法的准确性。然后研究了初始状态下纱线张力和排列角度等编织参数对预型件几何参数的影响。Flexural performance of reinforced concrete beams strengthened using near-surface-mounted carbon-fiber-reinforced polymer bars: Effects of bonding patternsJ.B. Lv, D.J. Lin, Bing Fu, S.H. Liu, Z.J. Handoi:10.1016/j.compstruct.2024.117985使用近表面安装的碳纤维增强聚合物条加固的钢筋混凝土梁的挠曲性能:粘结模式的影响The near-surface-mounted (NSM) fiber-reinforced polymer (FRP) technique is effective for enhancing the load carrying capacity of strengthened reinforced concrete (RC) beams. However, this technique significantly reduces the deformability of strengthened RC beams. To overcome this, the present study combines the NSM strengthening method with the partial bonding technique: the strengthening FRP reinforcement is partially bonded onto the concrete substrate). Six full-scale 4.3 m long RC beams strengthened with NSM FRPs using various bonding patterns were tested. The results indicated that mechanical interlocking grooves slightly improve the load carrying capacity, but have a negligible effect on the deformability of the strengthened beams. A decrease in the bond length increased deformability by 27.2 %, with only a 7.6 % drop in load capacity compared to that of the beam with full bonding. An advanced finite element model was developed and validated to confirm an optimal bond length of 930 mm for maximum flexural performance.近表面安装(NSM)纤维增强聚合物(FRP)技术可有效提高加固钢筋混凝土(RC)梁的承载能力。然而,这种技术大大降低了加固后 RC 梁的变形能力。为了克服这一问题,本研究将 NSM 加固方法与部分粘结技术相结合:将加固 FRP 钢筋部分粘结在混凝土基材上)。采用不同粘结模式的 NSM FRP 加固了六根长 4.3 米的全尺寸 RC 梁,并对其进行了测试。结果表明,机械互锁槽可略微提高承载能力,但对加固梁变形能力的影响微乎其微。与完全粘结的梁相比,粘结长度的减少使变形能力提高了 27.2%,而承载能力仅下降了 7.6%。开发并验证了一种先进的有限元模型,以确认最佳粘接长度为 930 毫米,从而实现最大抗弯性能。Composites Part A: Applied Science and ManufacturingRecycling CF/PEEK offcut waste from laser assisted tape placement: Influence of overlaps and gapsAswani Kumar Bandaru, Thomas Anderson, Paul M. Weaverdoi:10.1016/j.compositesa.2024.108104回收激光辅助胶带贴装产生的 CF/PEEK 废料:重叠和间隙的影响A recycling method for waste CF/PEEK prepreg tapes is proposed that uses offcuts from laser assisted tape placement (LATP) processing, without shredding, grinding or further cutting. Laminates (using the prepreg waste) representing different configurations were manufactured considering overlaps and gaps reflecting observed defects in LATP. Interlaminar shear strengths (ILSS) with 0° fibre (Parallel) and bending strength for 90° fibre (Normal) directions were measured. The parallel samples with 3 mm overlap had the highest ILSS (100.3 MPa) while the 2 mm gapped samples had the lowest ILSS (58.7 MPa). The Normal samples failed at the surface due to matrix-dominated failure providing bending strengths between 44.0 MPa and 82.1 MPa. Failure mechanisms were identified similar to that of non-recycled composites reported in the literature (50–120 MPa), indicating that the recycled prepreg tapes retained approximately 84 % of the ILSS of the highest reported values.本文提出了一种废 CF/PEEK 预浸料带的回收方法,该方法使用激光辅助贴带 (LATP) 加工过程中产生的边角料,无需粉碎、研磨或进一步切割。考虑到反映 LATP 中观察到的缺陷的重叠和间隙,制造了代表不同结构的层压板(使用预浸料废料)。测量了 0° 纤维方向(平行)的层间剪切强度(ILSS)和 90° 纤维方向(正常)的弯曲强度。重叠 3 毫米的平行样品的层间剪切强度最高(100.3 兆帕),而间隙为 2 毫米的样品的层间剪切强度最低(58.7 兆帕)。正常样品由于基质主导的失效而在表面失效,弯曲强度介于 44.0 兆帕和 82.1 兆帕之间。失效机制与文献报道的非回收复合材料的失效机制(50-120 兆帕)相似,表明回收预浸带保留了最高报道值约 84% 的 ILSS。Mechanical and interfacial analysis of 3D-printed two-matrix continuous carbon fibre composites for enhanced structural performanceFei Liu, Shenru Wang, Wuxiang Zhang, Xilun Ding, Eleonora Ferraris, Jan Ivensdoi:10.1016/j.compositesa.2024.108105增强结构性能的 3D 打印双基质连续碳纤维复合材料的力学和界面分析Two-matrix continuous carbon fibre composites are recognized for enhancing structural and mechanical properties. However, a comprehensive investigation into their interfacial behaviour and potential has yet to be undertaken. Based on the 3D printing process, this study uses experimental and simulation techniques to analyse the mechanical and interfacial performance across multiple scales. The flexure properties under different processing parameters are studied at the macro level. Meso and micro-structural characterization are evaluated by scanning electron microscopy, optical microscopy and molecular dynamics simulation. The disparities in simulations and experimental results are attributed to macroscopic defects and reinforcement volume fraction. This yields insights into strategies for optimising performance, culminating in a comprehensive understanding of the fracture mechanism of two-matrix continuous carbon fibre composites. Our study provides an approach to creating and analysing other systems with multiple matrix composites and enabling new engineering applications for composites.双基体连续碳纤维复合材料被认为可以提高结构和机械性能。然而,对其界面行为和潜力的全面研究尚未开展。本研究以三维打印工艺为基础,采用实验和模拟技术分析了多种尺度的机械和界面性能。从宏观层面研究了不同加工参数下的挠曲性能。通过扫描电子显微镜、光学显微镜和分子动力学模拟评估了中观和微观结构特征。模拟和实验结果的差异归因于宏观缺陷和增强体体积分数。这使我们对优化性能的策略有了深入的了解,最终对双基体连续碳纤维复合材料的断裂机制有了全面的认识。我们的研究为创建和分析其他多基体复合材料系统提供了一种方法,并使复合材料的新工程应用成为可能。Composites Part B: EngineeringFibre orientation distribution function mapping for short fibre polymer composite components from low resolution/large volume X-ray computed tomographyRobert M. Auenhammer, Anuj Prajapati, Kaldon Kalasho, Lars P. Mikkelsen, Philip J. Withers, Leif E. Asp, Renaud Gutkindoi:10.1016/j.compositesb.2024.111313通过低分辨率/大容积 X 射线计算机断层扫描绘制短纤维聚合物复合材料的纤维取向分布函数图Short glass fibre injection moulded composites, used in interior and exterior automotive parts, are exposed to complex stress states, for example during a crash. As the fibre scale dominates the composite’s material properties, numerical models need to account for the local fibre orientation. In recent years, mould flow simulation results have been exploited to predict the fibre orientations for finite element models, albeit with limited accuracy. Alternatively, X-ray computed tomography can be used to directly image and analyse fibre orientations. Traditionally, achieving the necessary resolution to image individual fibres restricts the imaging to small regions of the component. However, this study takes advantage of recent advancements in imaging and image analysis to overcome this limitation. As a result, it introduces, for the first time, a reliable, fast, and automated fibre orientation mapping for a full component based on image analysis on a single fibre level; even for cases where the pixel size is significantly larger than the fibre diameter. By scanning at lower resolutions, a drastically larger volume of interest can be achieve. The resulting fibre orientation analysis and mapping algorithm, based on X-ray computed tomography, is well matched to the level of information required for automotive crash modelling with a standard element-size of a few millimetres. The entire process, encompassing image acquisition, image analysis and fibre orientation mapping, can be directly integrated in an industrial full component application in a matter of hours.用于汽车内外饰件的短玻璃纤维注塑复合材料会面临复杂的应力状态,例如在碰撞过程中。由于纤维尺度主导着复合材料的材料特性,因此数值模型需要考虑局部纤维取向。近年来,人们利用模流模拟结果来预测有限元模型的纤维取向,尽管精确度有限。另外,X 射线计算机断层扫描也可用于直接成像和分析纤维取向。传统上,要达到成像单个纤维所需的分辨率,成像范围只能局限于部件的小区域。然而,本研究利用成像和图像分析领域的最新进展来克服这一限制。因此,该研究首次在单根纤维层面的图像分析基础上,为整个组件引入了可靠、快速和自动化的纤维方向映射;即使在像素尺寸明显大于纤维直径的情况下也是如此。通过低分辨率扫描,可以获得更大的感兴趣体积。由此产生的基于 X 射线计算机断层扫描的纤维方向分析和绘图算法,完全符合汽车碰撞建模所需的信息水平,其标准元素尺寸仅为几毫米。整个过程包括图像采集、图像分析和纤维取向绘图,可在数小时内直接集成到工业全部件应用中。Architected flexible syntactic foams: Additive manufacturing and reinforcing particle driven matrix segregationHridyesh Tewani, Megan Hinaus, Mayukh Talukdar, Hiroki Sone, Pavana Prabhakardoi:10.1016/j.compositesb.2024.111315结构化柔性合成泡沫:增材制造和增强粒子驱动的基质分离Polymer syntactic foams are transforming materials that will shape the future of next-generation aerospace and marine structures. When manufactured using traditional processes, like compression molding, syntactic foams consist of a solid continuous polymer matrix reinforced with stiff hollow particles. However, polymer matrix segregation can be achieved during the selective laser sintering process with thermoplastic polyurethane (TPU). It is uncertain what role hollow particles play in forming this matrix segregation and its impact on the corresponding mechanical properties of syntactic foams. We show that the size of the hollow particles controls the internal microscale morphology of matrix segregation, leading to counter-intuitive macroscale mechanical responses. Particles with diameters greater than the gaps between the cell walls of the segregated matrix get lodged between and in the walls, bridging the gaps in the segregated matrix and increasing the stiffness of syntactic foams. In contrast, particles with smaller diameters with higher particle crushing strength get lodged only inside the cell walls of the segregated matrix, resulting in higher densification stresses (energy absorption). We show that stiffness and densification can be tuned while enabling lightweight syntactic foams. These novel discoveries will aid in facilitating functional and lightweight syntactic foams for cores in sandwich structures.聚合物合成泡沫是一种变革性材料,它将塑造下一代航空航天和海洋结构的未来。在使用压缩成型等传统工艺制造时,合成泡沫由固态连续聚合物基体和硬质空心颗粒组成。然而,在热塑性聚氨酯(TPU)的选择性激光烧结过程中,聚合物基质会发生偏析。目前还不确定空心颗粒在形成这种基质偏析中起到什么作用,以及它对合成泡沫相应机械性能的影响。我们的研究表明,中空颗粒的大小控制着基质离析的内部微观形态,从而导致与直觉相反的宏观机械响应。直径大于离析基质细胞壁间隙的颗粒会嵌入细胞壁之间和细胞壁内,从而弥合离析基质的间隙,增加合成泡沫的刚度。相反,直径较小、颗粒破碎强度较高的颗粒只能嵌入离析基质的细胞壁内,从而导致较高的致密化应力(能量吸收)。我们的研究表明,在实现轻质合成泡沫的同时,还可以调整刚度和致密性。这些新发现将有助于促进功能性轻质合成泡沫在夹层结构中的核心应用。A Novel machine learning model to design historical-independent health indicators for composite structuresMorteza Moradi, Ferda C. Gul, Dimitrios Zarouchasdoi:10.1016/j.compositesb.2024.111328 设计与历史无关的复合材料结构健康指标的新型机器学习模型Developing comprehensive health indicators (HIs) for composite structures encompassing various damage types is challenging due to the stochastic nature of damage accumulation and uncertain events (like impact) during operation. This complexity is amplified when striving for HIs independent of historical data. This paper introduces an AI-driven approach, the Hilbert transform-convolutional neural network under a semi-supervised learning paradigm, to designing reliable HIs (fulfilling requirements, referred to as &#39;fitness&#39;). It exclusively utilizes current guided wave data, eliminating the need for historical information. Ensemble learning techniques were also used to enhance HI quality while reducing deep learning randomness. The fitness equation is refined for dependable comparisons and practicality. The methodology is validated through investigations on T-single stiffener CFRP panels under compression-fatigue and dogbone CFRP specimens under tension-fatigue loadings, showing high performance of up to 93% and 81%, respectively, in prognostic criteria.由于损伤累积的随机性和运行期间的不确定事件(如撞击),为包含各种损伤类型的复合材料结构制定全面的健康指标(HIs)具有挑战性。在寻求独立于历史数据的健康指标时,这种复杂性会进一步放大。本文介绍了一种人工智能驱动的方法,即半监督学习范式下的希尔伯特变换-卷积神经网络,用于设计可靠的 HI(满足要求,称为 &quot;适配性&quot;)。它完全利用当前的导波数据,无需历史信息。此外,还使用了集 合学习技术来提高 HI 质量,同时减少深度学习的随机性。为了实现可靠的比较和实用性,对适度方程进行了改进。通过对压缩疲劳下的 T 型单加强筋 CFRP 面板和拉伸疲劳载荷下的狗骨 CFRP 试样进行研究,验证了该方法,结果表明其在预后标准方面的性能分别高达 93% 和 81%。Composites Science and TechnologyA novel one-step eco-friendly dipping system for PA66 fiber/rubber composites with excellent interfacial adhesion and its adhesion mechanismChaojun Wang, Xuewen Cheng, Wei Huang, Bing Yu, Nanying Ning, Ming Tiandoi:10.1016/j.compscitech.2024.110513 具有优异界面粘附力的 PA66 纤维/橡胶复合材料的新型一步法环保浸渍系统及其粘附机理Fiber-reinforced rubber composites (FRRC) are widely used in tires, hoses, conveyor belts and other fields. Currently, the industry heavily relies on the resorcinol-formaldehyde-latex (RFL) system to enhance interfacial adhesion performance of FRRC; however, both resorcinol (R) and formaldehyde (F) pose significant risks to human health and the environment. Thus, some two-step RF-free dipping systems have been developed to replace RFL system. Nevertheless, these complex two-step systems face challenges during industrialization. In this study, we proposed a novel one-step eco-friendly dipping system (PCGL) for PA66 fibers. By using the new system, a solid transition bridge between PA66 fiber and rubber matrix can be formed, due to the bonding between PA66 and isocyanate, the interaction among polyacrylic acid resin, isocyanate and epoxy, the catalytic effect of triethanolamine, as well as the co-crosslinking of styrene-butadiene-vinyl-pyridine latex and rubber. The interfacial adhesion performance of PA66 fiber/rubber composites treated by PCGL with optimized ratio of epoxy groups/isocyanate groups can reach more than 90% of RFL level, meeting industry requirements for high interfacial bonding performance, while maintaining strength and safety of composites. The mechanism of largely enhanced interfacial adhesion was revealed through the analysis of modulus transition and co-crosslinking at the composite interface.纤维增强橡胶复合材料(FRRC)广泛应用于轮胎、软管、传送带等领域。目前,该行业主要依赖间苯二酚-甲醛-乳胶(RFL)系统来提高 FRRC 的界面粘合性能;然而,间苯二酚(R)和甲醛(F)都会对人类健康和环境造成严重危害。因此,人们开发了一些两步无射频浸渍系统来取代 RFL 系统。然而,这些复杂的两步法系统在工业化过程中面临着挑战。在本研究中,我们针对 PA66 纤维提出了一种新型的一步法环保浸渍系统(PCGL)。通过使用这种新体系,PA66 纤维与橡胶基体之间可以形成固体过渡桥,这是由于 PA66 与异氰酸酯之间的粘合作用,聚丙烯酸树脂、异氰酸酯和环氧树脂之间的相互作用,三乙醇胺的催化作用,以及苯乙烯-丁二烯-乙烯基吡啶胶乳与橡胶的共交联作用。环氧基团/异氰酸酯基团比例优化的 PCGL 处理的 PA66 纤维/橡胶复合材料的界面粘合性能可达 RFL 水平的 90% 以上,满足了行业对高界面粘合性能的要求,同时保持了复合材料的强度和安全性。通过分析复合材料界面的模量转变和共交联,揭示了界面粘合力大幅增强的机理。来源:复合材料力学仿真Composites FEM

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