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【新文速递】2024年6月7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

Shape-retaining beam-like morphing structures via localized snap through

Asifur Rahman, Samuele Ferracin, Sujata Tank, Chris Zhang, Paolo Celli

doi:10.1016/j.ijsolstr.2024.112917

保持形状的梁状变形结构通过局部snap通过

In this study, we present a concept of morphing structure – featuring an arch mounted on a compliant base – that can be reconfigured via snap-through buckling and leverages bistability to retain its morphed shape. We show that one-dimensional arrays of such units yield beam-like structures that, upon localized snapping, can attain multiple, morphologically distinct stable shapes. Units are modeled using discrete elastic rods, a reduced-order formulation for beams and beam structures, and the results are validated via experiments. We leverage our model to understand the influence of the geometrical design parameters on the response and final shape of a unit. We then show that the morphed shapes of arrays of units can be predicted by concatenating results of simulations on single units, and leverage this idea to inverse-design structures that can be snapped into target stable shapes. Ultimately, our work suggests an up-scalable way to create shape-retaining morphing structures with target stable shapes.

在这项研究中,我们提出了一种变形结构的概念-具有安装在柔性基座上的拱门-可以通过卡扣 扣重新配置,并利用双稳定性来保持其变形形状。我们展示了这种单元的一维阵列产生的梁状结构,在局部捕获后,可以获得多个,形态上不同的稳定形状。单元使用离散弹性杆建模,这是梁和梁结构的降阶公式,并通过实验验证了结果。我们利用我们的模型来理解几何设计参数对单元响应和最终形状的影响。然后,我们展示了单元阵列的变形形状可以通过连接单个单元的模拟结果来预测,并利用这一想法来逆向设计可以快速进入目标稳定形状的结构。最终,我们的工作提出了一种可扩展的方法来创建具有目标稳定形状的保持形状的变形结构。


Journal of the Mechanics and Physics of Solids

Effective boundary conditions for second-order homogenization

Manon Thbaut, Basile Audoly, Claire Lestringant

doi:10.1016/j.jmps.2024.105707

二阶均匀化的有效边界条件

Using matched asymptotic expansions, we derive an equivalent bar model for a periodic, one-dimensional lattice made up of linear elastic springs connecting both nearest and next-nearest neighbors. We obtain a strain-gradient model with effective boundary conditions capturing the boundary layers forming at the endpoints. It is accurate to second order in the scale separation parameter ɛ≪1, as shown by a comparison with the solution to the discrete lattice problem. The homogenized modulus associated with the gradient effect (gradient stiffness) is found negative, as is often the case in second-order homogenization. Negative gradient stiffnesses are widely viewed as paradoxical as they can induce short-wavelength oscillations in the homogenized solution. In the one-dimensional lattice, the asymptotically correct boundary conditions are shown to suppress the oscillations, thereby restoring consistency. By contrast, most of the existing work on second-order homogenization makes use of postulated boundary conditions which, we argue, not only ruin the order of the approximation but are also the root cause of the undesirable oscillations.

利用匹配渐近展开法,我们推导出了由连接最近和次近邻的线性弹性弹簧组成的周期性一维晶格的等效棒模型。我们得到了一个应变梯度模型,其有效边界条件捕捉到了端点处形成的边界层。通过与离散晶格问题的解进行比较,可以看出该模型的精确度达到了尺度分离参数ɛ≪1 的二阶。与梯度效应相关的均质化模量(梯度刚度)为负值,这在二阶均质化中很常见。人们普遍认为负梯度刚度是自相矛盾的,因为它会在均质化解中引起短波长振荡。在一维晶格中,渐近正确的边界条件可以抑制振荡,从而恢复一致性。相比之下,大多数现有的二阶均质化研究都使用了假定的边界条件,我们认为这些条件不仅破坏了近似的阶次,而且是产生不良振荡的根本原因。


Mechanics of Materials

Statistical description of fracture toughness revisited: Implications for evaluation of the reference temperature, T0, and characteristic fracture toughness

Claudio Ruggieri, Luís G.T.S. Leite, Daniel C.F. Ferreira

doi:10.1016/j.mechmat.2024.105055

重新审视断裂韧性的统计描述: 对参考温度 T0 和特征断裂韧性评估的影响

The present study focuses on further extensions of the more general three-parameter Weibull distribution to describe the statistical scatter of fracture toughness values and to evaluate the characteristic toughness of structural steels using a statistical description of toughness data in comparison with the minimum of three equivalent (MOTE) method. Fracture toughness tests conducted on several types of structural steels, including an ultra high strength steel and pressure vessel steels, provide the experimental data upon which the Weibull statistical analyses are conducted. These analyses compare descriptions of fracture toughness values based on a standard three-parameter Weibull function with fixed values for parameters α and Kmin, and a general three-parameter Weibull distribution with unknown parameters (α,K0, Kmin) in connection with a goodness-of-fit method to assess how well the experimental data fits the assumed distribution. Further, the study also shows that use of a fixed percentile of the distribution describing the toughness data set provides more consistent values of characteristic toughness compared to the MOTE procedure.

本研究的重点是进一步扩展更一般的三参数威布尔分布,以描述断裂韧性值的统计散布,并使用韧性数据的统计描述与最小三当量法(MOTE)进行比较,评估结构钢的特征韧性。对几种结构钢(包括一种超高强度钢和压力容器钢)进行的断裂韧性测试提供了进行 Weibull 统计分析所依据的实验数据。这些分析比较了基于参数 α 和 Kmin 固定值的标准三参数 Weibull 函数和未知参数(α、K0、Kmin)的一般三参数 Weibull 分布对断裂韧性值的描述,并结合拟合优度法评估实验数据与假定分布的拟合程度。此外,研究还表明,与 MOTE 程序相比,使用描述韧性数据集的分布的固定百分位数可提供更一致的特性韧性值。


Thin-Walled Structures

Prediction of machining deformation for circular metallic plates under residual stress and clamping force in turning

Kang Ju, Chunzheng Duan, Yuwen Sun, Jiahao Shi, Abdolhamid Akbarzadeh

doi:10.1016/j.tws.2024.112049

车削过程中残余应力和夹紧力作用下圆形金属板加工变形预测

Workpiece deformation under the coupling effect of clamping force, initial residual stress (IRS), and machining residual stress (MRS) is an essential concern in the manufacturing of thin-walled metallic parts. Prediction of machining deformations is critical for ensuring machining quality and has significant guiding implications for producing thin-walled parts. However, most research has been focused on calculating machining deformation caused by a single factor. Based on the energy principle, the effect of clamping deformation on the material removal amount and the effect of the cyclic material removal process on both IRS and MRS are analyzed. To predict the machining deformation of circular metallic plates, energy functions under the three-dimensional non-uniform residual stress field consider the coupling effect of multiple factors, which is established and solved by the Raleigh-Ritz method. This analysis elucidates the formation mechanism of machining deformation under the single-factor effects of IRS and MRS as well as the coupling effect of clamping force and residual stress. In this article, an analytical prediction model with a prediction error of around 8.5% is established for machining deformation under the coupling effect. Additionally, leveraging the quantitative results of the proposed model, the impacts of cutting parameters and strategies on machining deformation, as well as the evolution of machining deformation throughout the entire material removal process are elicited.

夹紧力、初始残余应力(IRS)和加工残余应力(MRS)耦合作用下的工件变形是薄壁金属零件制造中的一个重要问题。加工变形预测是保证加工质量的关键,对薄壁件的生产具有重要的指导意义。然而,大多数研究都集中在计算由单一因素引起的加工变形上。基于能量原理,分析了夹紧变形对材料去除量的影响以及循环去除过程对IRS和MRS的影响。为预测圆形金属板的加工变形,建立了三维非均匀残余应力场下考虑多因素耦合效应的能量函数,并采用罗利-里兹法求解。分析了IRS和MRS单因素作用下加工变形的形成机理以及夹紧力和残余应力的耦合作用。本文建立了耦合作用下加工变形的解析预测模型,预测误差在8.5%左右。此外,利用所提出的模型的定量结果,得出切削参数和策略对加工变形的影响,以及在整个材料去除过程中加工变形的演变。


Inter-layer failure and toughening mechanisms of carbon/aramid hybrid fiber composites interleaved with micro/nano pulps under low-velocity impact load

Hangyan Wang, Yang Lin, Hongyong Jiang, Zhihui Liu

doi:10.1016/j.tws.2024.112086

微纳浆与碳/芳纶混杂纤维复合材料在低速冲击载荷下的层间破坏及增韧机理

Hybrid fiber-reinforced polymer (HFRP) composites are widely used in aerospace structures because of their excellent overall performance. However, it is still challenging to address the issue of high sensitivity to delamination between dissimilar material interlayers in HFRP composites. This study combines experimental and numerical simulation to analyze the low-velocity impact behavior and interlaminar damage of two types of HFRP. Based on a micromechanical model, an equivalent aramid pulp (eAP) toughening laminate model is developed. The impact behavior of the HFRP toughen by eAP only in dissimilar material interlayers is simulated based on the model. The effect of eAP areal density on the impact behavior and evolution of interlaminar damage is analyzed. Results show that the maximum force and impact stiffness of eAP-toughened HFRP increase initially with the increase in eAP areal density, and then decrease slowly. The area and extent of damage of dissimilar material interlayers in eAP toughened laminates is significantly reduced. Finally, the interlaminar toughening and failure mechanisms by eAP-toughening only in dissimilar material interlayers of the HFRP composites are systematically revealed from fiber bridging and damage transfer perspectives.

混杂纤维增强聚合物(HFRP)复合材料以其优异的综合性能在航空航天结构中得到广泛应用。然而,解决HFRP复合材料中不同材料夹层间分层的高敏感性问题仍然具有挑战性。本研究采用实验与数值模拟相结合的方法,对两种HFRP材料的低速冲击行为和层间损伤进行了分析。在微观力学模型的基础上,建立了等效芳纶浆料增韧层压模型。基于该模型,模拟了eAP增韧HFRP在不同材料层间的冲击行为。分析了eAP面密度对冲击行为和层间损伤演化的影响。结果表明:eAP增韧HFRP的最大受力和冲击刚度随eAP面密度的增加先增大后缓慢减小;eAP增韧层合板中异种材料间层的损伤面积和程度明显减小。最后,从纤维桥接和损伤传递的角度系统揭示了eap增韧在HFRP复合材料不同材料层间的层间增韧和破坏机制。


Dynamic response analysis of monopile CFDST wind turbine tower system under wind-wave-seismic coupling action

Li-Xin Duan, Wen-Da Wang, Long Zheng, Yan-Li Shi

doi:10.1016/j.tws.2024.112089

风波-地震耦合作用下单桩CFDST风塔系统动力响应分析

The dynamic response of monopile-supported offshore wind turbine tower (OWT) structures under seismic action in undrained conditions is analyzed using ABAQUS. A typical example is established by using the NREL5MW OC3 Monopile wind turbine tower as a prototype. The aim is to compare the seismic performance of concrete-filled double-skin steel tubes (CFDST) and steel structural wind turbine tower systems. The impact of seismic incidence angles on the dynamic response of both types of wind turbine towers is investigated. Combining OpenFAST, a sophisticated numerical model for the multi-hazard coupling is also established for both CFDST and steel structural offshore monopile wind turbine tower systems. The influence of various loads on the tower top acceleration, tower top displacement, base shear, and base moment for the aforementioned two types of wind turbine tower systems is studied. The results indicate that under the coupling effects of wind, waves, and seismic forces, the monopile CFDST wind turbine tower system exhibits superior seismic performance, operational stability, and safety compared to traditional steel wind turbine tower systems, and has better development prospects.

采用ABAQUS软件,分析了不排水条件下单桩支撑海上风电塔架结构在地震作用下的动力响应。以NREL5MW OC3单桩风力机塔架为原型,建立了典型实例。目的是比较双皮钢管混凝土(CFDST)和钢结构风塔系统的抗震性能。研究了地震入射角对两种风塔动力响应的影响。结合OpenFAST,建立了CFDST和钢结构海上单桩风电塔架系统多危害耦合的复杂数值模型。研究了不同荷载对上述两种风力机塔架系统塔顶加速度、塔顶位移、基础剪力和基础弯矩的影响。结果表明,在风、波、地震力的耦合作用下,单桩CFDST风塔体系比传统钢结构风塔体系具有更优越的抗震性能、运行稳定性和安全性,具有更好的发展前景。




来源:复合材料力学仿真Composites FEM
ACTMechanicalSystemAbaqusDeform断裂复合材料航空航天材料
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首次发布时间:2024-11-20
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【新文速递】2024年6月11日复合材料SCI期刊最新文章

今日更新:Composite Structures 4 篇,Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 3 篇Composite StructuresLine finite element method for geometrically nonlinear analysis of functionally graded members accounting for twisting effectsGuanghua Li, Zi-Zhang Gu, Hao-Yi Zhang, Weihang Ouyang, Si-Wei Liudoi:10.1016/j.compstruct.2024.118268 考虑扭转效应的功能梯度构件几何非线性分析的线有限元方法Functionally graded materials with spatially varying properties have gained widespread use in various engineering disciplines due to their exceptional mechanical characteristics. Nevertheless, these materials can lead to non-symmetric properties of cross-sections and an offset between centroid and shear center of functionally graded (FG) members, thereby significantly affecting the mechanical behavior. This phenomenon, known as twisting effects, poses a substantial challenge for the geometrically nonlinear analysis of FG members, as existing methods rely on traditional beam-column elements that assume the centroid and shear center of sections coincide. Thus, this paper proposes a new framework for geometrically nonlinear analysis of FG members, incorporating twisting effects through a novel Timoshenko beam-column element. An efficient finite-element-based approach that employs the nonhomogeneous plane triangle (NPT) element for calculating the cross-sectional properties of arbitrary FG cross-sections is presented. These cross-sectional properties are then utilized within the advanced line-element formulation to perform geometrically nonlinear analysis of FG structures considering twisting effects. The accuracy of the proposed method is validated through three examples, followed by several case studies to examine the impact of twisting effects on FG members. Furthermore, the proposed cross-section analysis method is integrated into a new structural analysis software MSASect2 to facilitate its application.具有空间变化特性的功能梯度材料由于其优异的力学特性在各种工程学科中得到了广泛的应用。然而,这些材料会导致功能梯度(FG)构件的截面非对称特性和质心与剪切中心之间的偏移,从而显著影响力学行为。这种被称为扭转效应的现象对FG构件的几何非线性分析提出了实质性的挑战,因为现有的方法依赖于传统的梁柱单元,假设截面的质心和剪切中心重合。因此,本文提出了一种新的框架,用于FG构件的几何非线性分析,通过一种新的Timoshenko梁柱单元纳入扭转效应。提出了一种利用非均匀平面三角形(NPT)单元计算任意FG截面截面特性的有效有限元方法。这些截面特性然后在先进的线素公式中被利用,以执行考虑扭转效应的FG结构的几何非线性分析。通过三个实例验证了所提出方法的准确性,然后通过几个案例研究来检查扭转效应对FG构件的影响。此外,本文还将所提出的截面分析方法集成到新的结构分析软件MSASect2中,以方便其应用。Review on mechanical properties of metal lattice structuresXun Miao, Jianxin Hu, Yiyi Xu, Jun Su, Yang Jingdoi:10.1016/j.compstruct.2024.118267金属晶格结构力学性能研究进展Metallic lattice structures are garnering increasing attention across various research domains for their potential to create lightweight yet high-strength solutions. Their appeal largely stems from a range of beneficial attributes, including their low weight, substantial specific strength and stiffness, and superior energy absorption qualities. These characteristics have facilitated their widespread use in industries like aerospace, shipping, defense, and automotive, particularly in scenarios demanding weight minimization, multifunctionality, and enhanced safety in intricate environments. The mechanical properties of these structures are, therefore, of paramount importance. This paper offers an exhaustive review and synthesis of existing research approaches, production techniques, and evaluations of both static and dynamic mechanical properties associated with metallic lattice structures. It starts by delineating the various types and manufacturing methods, followed by an analysis of factors impacting their mechanical properties. The paper concludes by exploring prospective research avenues concerning the static and dynamic mechanical performance of metallic lattice structures.金属晶格结构因其创造轻质高强度解决方案的潜力而在各个研究领域受到越来越多的关注。它们的吸引力很大程度上源于一系列有益的属性,包括它们的低重量,可观的比强度和刚度,以及优越的能量吸收特性。这些特性促进了它们在航空航天、航运、国防和汽车等行业的广泛应用,特别是在复杂环境中要求重量最小化、多功能和增强安全性的场景中。因此,这些结构的力学性能是至关重要的。本文对现有的研究方法、生产技术以及与金属晶格结构相关的静态和动态力学性能的评估进行了详尽的回顾和综合。它首先描述了各种类型和制造方法,然后分析了影响其机械性能的因素。最后,对金属晶格结构静动力力学性能的研究方向进行了展望。A Transformer-based neural network for automatic delamination characterization of quartz fiber-reinforced polymer curved structure using improved THz-TDSQiuhan Liu, Qiang Wang, Jiansheng Guo, Wenquan Liu, Ruicong Xia, Jiayang Yu, Xinghao Wangdoi:10.1016/j.compstruct.2024.118272基于Transformer的神经网络用于石英纤维增强聚合物弯曲结构的自动分层表征Quartz fiber-reinforced polymer (QFRP) is a vital non-polar material used in aviation wave-transparent structural components. Automatic characterization of delamination defects in QFRP is critical to aviation structural component safety. Terahertz time-domain spectroscopy (THz-TDS) is one of the new non-destructive testing (NDT) methods with highly accurate characterization of internal defects in non-polar material. Hence, attempts to extract features of THz time-domain signals for automatic characterization have been made by using deep learning algorithms. In this work, a Transformer-based neural network to classify the THz time-domain signals collected from a QFRP curved structure for automatic characterization of pre-embedded delamination defects has been reported. A THz-TDS system combined with a collaborative robot for collecting the THz signals from QFRP curved structure has been built. An automatic characterization method framework is developed. Results show that the precision rates of Transformer-based neural network for 1st delamination to 5th delamination are 1.0, 1.0, 1.0, 0.985, 1.0, and F1 score of it is 0.982. During the process of testing, delamination defects inside the QFRP curved structure were visualized using pixels with different colors. Results indicate that the Transformer-based neural network can characterize all pre-embedded delamination defects while minimizing false identification of non-defective areas, performing outstanding generalization.石英纤维增强聚合物(QFRP)是一种重要的非极性材料,用于航空透波结构部件。自动表征 QFRP 中的分层缺陷对航空结构部件的安全性至关重要。太赫兹时域光谱(THz-TDS)是一种新型无损检测(NDT)方法,可对非极性材料的内部缺陷进行高精度表征。因此,人们尝试使用深度学习算法来提取太赫兹时域信号的特征,以便进行自动表征。在这项工作中,报告了一种基于变压器的神经网络,用于对从 QFRP 曲线结构中收集到的太赫兹时域信号进行分类,以自动表征预埋分层缺陷。建立了一个 THz-TDS 系统,该系统与协作机器人相结合,用于从 QFRP 曲面结构中采集 THz 信号。开发了自动表征方法框架。结果表明,基于变压器的神经网络对第 1 层分层至第 5 层分层的精确率分别为 1.0、1.0、1.0、0.985、1.0,其 F1 分数为 0.982。在测试过程中,QFRP 曲线结构内部的分层缺陷用不同颜色的像素可视化显示。结果表明,基于变压器的神经网络可以表征所有预埋分层缺陷,同时最大限度地减少对非缺陷区域的错误识别,具有出色的泛化能力。Form-finding of thermal-adaptive pin-bar assemblies based on eigenvalue modificationHongchuang Liu, Hua Dengdoi:10.1016/j.compstruct.2024.118275基于特征值修正的热自适应针杆组件寻形Lattice structures with tunable expansion properties have been investigated in multidisciplinary fields to control the temperature effects of structures or materials. The expected thermal adaptivity can be achieved by optimizing the structural geometry. A novel method for the form-finding of thermal-adaptive pin-bar assemblies is developed in this paper by considering the control of structural temperature effects as the minimization of the potential energy of the system. Based on the stationarity condition of the potential energy with respect to the nodal coordinates, the compatibility relationship between the thermal elongations of members and the target nodal displacements is proven to be the sufficient and necessary condition for structural thermal adaptivity. The solvability of the compatibility equation is determined by the rank equality between the compatibility matrix and its augmented form, which can be measured by the number of nonzero eigenvalues of its Gramian matrix. The analytical relationship between the eigenvalues of the Gramian matrix and the nodal coordinates is established using the matrix perturbation theory. A numerical strategy based on Newton’s method is proposed in which the eigenvalues are gradually modified by adjusting the nodal coordinates until the rank equality is satisfied. To address the existence of multiple solutions with structural thermal adaptivity, structural symmetry and periodicity constraints are introduced to narrow the solution space. The thermal-adaptive configurations of three illustrative pin-bar assemblies are analyzed using the proposed form-finding method, and the expected thermal deformations are verified for the obtained configurations using the finite element software ABAQUS. Comparing the results obtained by the proposed method with those obtained by nonlinear programming and the genetic algorithm validates the advantages of the proposed method in terms of computational time, optimality of the obtained configuration and applicability to complex structural geometries.具有可调膨胀特性的晶格结构在多学科领域得到了广泛的研究,用于控制结构或材料的温度效应。通过优化结构的几何形状,可以达到预期的热适应性。将结构温度效应控制作为系统势能的最小化,提出了一种热自适应针杆组件寻形的新方法。基于势能相对于节点坐标的平稳条件,证明了构件热伸长与目标节点位移的相容关系是结构热自适应的充要条件。相容方程的可解性由相容矩阵与其增广形式之间的秩相等决定,可由相容矩阵的非零特征值的个数来衡量。利用矩阵摄动理论建立了格拉姆矩阵的特征值与节点坐标的解析关系。提出了一种基于牛顿法的数值策略,通过调整节点坐标逐渐修正特征值,直至满足秩相等。为了解决具有结构热自适应的多解的存在性,引入结构对称性和周期性约束来缩小解空间。采用所提出的寻形方法对3个典型销杆组件的热自适应结构进行了分析,并利用有限元软件ABAQUS对得到的结构进行了预期热变形验证。将所提方法与非线性规划和遗传算法的计算结果进行了比较,验证了所提方法在计算时间短、构型最优性好、适用于复杂几何结构等方面的优势。Composites Part A: Applied Science and ManufacturingA direct correlation between damage parameters and effective permeation coefficients in composite laminatesRaffael Bogenfeld, Caroline Lüders, Michael Ebermann, Vineeth Ravidoi:10.1016/j.compositesa.2024.108307复合材料层合板损伤参数与有效渗透系数之间的直接关系We introduce an innovative approach for determining the gas permeability of composite laminates, explicitly accounting for inter-fiber fracture. Our method forges a direct correlation between the Continuum Damage Mechanics (CDM) damage parameter for transverse inter-fiber fracture and the effective permeation coefficients, which are crucial in assessing leak tightness. This correlation stems from a geometric similarity between the ratio of the damaged material’s load-carrying capacity to that of its pristine state, and the relative projected crack length as crucial parameter for the effective permeability assessment. This CDM-based approach represents a significant advancement in directly deriving a laminate’s permeability from mechanical failure analysis results. This is essential for the design process of Type V hydrogen storage tanks. Literature-based experimental results validate the plausibility of our method, proving its effectiveness across various laminate orientations and damage scenarios. Nonetheless, the observed deviations highlight the need for detailed damage information, elaborate material characterization.我们介绍了一种创新的方法来确定复合材料层合板的透气性,明确地考虑纤维间断裂。我们的方法在横向纤维间断裂的连续损伤力学(CDM)损伤参数与有效渗透系数之间建立了直接关联,而有效渗透系数是评估泄漏密封性的关键。这种相关性源于损坏材料的承载能力与其原始状态的承载能力之比之间的几何相似性,以及相对预计裂缝长度作为有效渗透率评估的关键参数。这种基于cdm的方法在直接从机械失效分析结果中得出层压板的渗透率方面取得了重大进展。这对V型储氢罐的设计过程至关重要。基于文献的实验结果验证了我们的方法的合理性,证明了它在各种层压板方向和损伤场景下的有效性。尽管如此,观察到的偏差强调需要详细的损伤信息,详细的材料表征。Composites Part B: EngineeringMillefeuille-inspired biomass alternate multilayer composite, for excellent absorption-dominated, broadband EMI shielding and Joule heatingQi Zhang, Xiaohong Tang, Qian Zhao, Xianchun Chen, Ke Wang, Qin Zhang, Qiang Fudoi:10.1016/j.compositesb.2024.111620 千叶启发的生物质交替多层复合材料,具有优异的吸收主导,宽带EMI屏蔽和焦耳加热The development of biomass electromagnetic interference (EMI) shielding materials with low cost, low reflection(R-value), and high shielding efficiency is promising but also challenging. Inspired by the alternate structure of a millefeuille, we propose an alternating assembly approach for conductive and magnetic layers. Employing sustainable bamboo fibers (BF) and biodegradable polylactic acid (PLA) as raw matrix, the magnetic and conductive layers were fabricated by compositing copper-plated BF (Cu@BF) and iron-plated BF (Fe@BF) with PLA, respectively. By alternately stacking magnetic and conductive layers and followed by hot pressing, the high EMI SE and low R-value biomass multilayer composite with “multi-(absorption-reflection-reabsorption)” structures were obtained. The performance of different alternating layers (3/5/7/9 layers) was studied, and a linear correlation between layer number, SE, and R-value was established. The results demonstrate that increasing the alternate layer number could readily tune the SE in the X-band from 45.02 dB (3-layer) to 80.2 dB (9-layer) and reduce Rmin from 0.40 to 0.25. Furthermore, the 9-layer composite exhibits approximately 75 dB SE in 1-18 GHz, simultaneously realizing high efficiency, low reflectivity, and broadband shielding. Notably, its excellent conductivity also provides reliable Joule heating performance. The shielding and thermal features of the composite highlight its potential in construction and smart housing heating applications.开发低成本、低反射(r值)、高屏蔽效率的生物质电磁干扰(EMI)屏蔽材料是有前景的,但也具有挑战性。受千费耶交替结构的启发,我们提出了导电层和磁性层交替组装的方法。以可持续竹纤维(BF)和可生物降解聚乳酸(PLA)为原料,分别用镀铜BF (Cu@BF)和镀铁BF (Fe@BF)与PLA复合制备磁性和导电层。通过磁性层和导电层交替叠加,然后进行热压,获得了具有“多(吸收-反射-重吸收)”结构的高电磁干扰SE和低r值生物质多层复合材料。研究了不同交替层(3/5/7/9层)的性能,发现层数、SE和r值之间存在线性相关关系。结果表明,增加交替层数可以很容易地将x波段的SE从45.02 dB(3层)调整到80.2 dB(9层),并将Rmin从0.40降低到0.25。此外,9层复合材料在1-18 GHz范围内的SE约为75 dB,同时实现了高效率、低反射率和宽带屏蔽。值得注意的是,其优异的导电性也提供了可靠的焦耳加热性能。复合材料的屏蔽和热特性突出了其在建筑和智能住宅供暖应用中的潜力。Composites Science and TechnologyMussel-Inspired Structure based CsPbBr3/Aramid Nanofiber Composite Film for Lightweight, Flexible and Superior X-ray ShieldingZizhan Guo, Zhaoqing Lu, Guoqiang Peng, Jingru Zhang, Li Hua, Fengfeng Jia, Jiayue Dong, Qijun Li, Haoxu Wang, Zhiwen Jindoi:10.1016/j.compscitech.2024.110700 基于贻贝启发结构的CsPbBr3/芳纶纳米纤维复合薄膜,用于轻质、柔性和卓越的x射线屏蔽Excessive exposure to X-rays risks human health and the proper functioning of precision instruments. Conventional materials have high atomic numbers, but their unsatisfactory mechanical properties hinder commercial application. Currently, X-ray shielding materials must fulfill the characteristics of high strength, lightweight, flexibility, high shielding efficiency, and low secondary radiation to alleviate urgent radiation risks. Here, this work introduces a mussel-inspired structure into the construction of the lightweight and flexible CsPbBr3/aramid nanofiber (ANF) composite films to enhance the ability of X-ray absorption. The CsPbBr3 provides effective X-ray shielding in millimeter thickness and addresses the challenge of absorption zone matching by containing both Cs and Pb elements. The interlayer reflection caused by the mussel-inspired structure increases the photon travel distance in the film, which synergizes with the absorption of X-rays by the elements, significantly improving shielding performance and weakening secondary radiation. The CsPbBr3/ANF composite film with 60 wt% CsPbBr3 content demonstrates robust tensile stress (57.6 MPa), lightweight (0.87 g/cm3), superior heat resistance, exceptional flexibility with a notable mass attenuation coefficient (58.2-65.6 cm2/g in the 20-70 kV range), which is much higher than Pb plate. Considering its comprehensive performance advantages, the CsPbBr3/ANF composite film significantly impacts the landscape of X-ray shielding.过度暴露于x射线会危及人体健康和精密仪器的正常工作。传统材料原子序数高,但力学性能不理想,阻碍了其商业应用。当前,x射线屏蔽材料必须具备高强度、轻量化、柔韧性、高屏蔽效率、低二次辐射等特点,才能缓解迫在眉睫的辐射风险。在这里,本研究将贻贝启发的结构引入到轻质柔性CsPbBr3/芳纶纳米纤维(ANF)复合薄膜的构建中,以增强x射线吸收能力。CsPbBr3在毫米厚度上提供了有效的x射线屏蔽,并通过同时含有Cs和Pb元素来解决吸收区匹配的挑战。贻贝启发结构引起的层间反射增加了光子在薄膜中的传播距离,与元件对x射线的吸收协同作用,显著提高了屏蔽性能,减弱了二次辐射。CsPbBr3含量为60 wt%的CsPbBr3/ANF复合薄膜具有抗拉应力(57.6 MPa)、重量轻(0.87 g/cm3)、耐热性好、柔韧性好、质量衰减系数显著(20-70 kV范围内58.2-65.6 cm2/g),远高于铅板。考虑到CsPbBr3/ANF复合薄膜的综合性能优势,其对x射线屏蔽的影响是显著的。Functionalization of Calcium-Deficient Nanohydroxyapatite Improves the Mechanical Properties of 3D Printed Biopolymer NanocompositesDibakar Mondal, Thomas L. Willettdoi:10.1016/j.compscitech.2024.110707 缺钙纳米羟基磷灰石功能化改善3D打印生物聚合物纳米复合材料的力学性能Agglomerations of nanoparticles in a polymer matrix can drastically reduce the mechanical properties of a polymer nanocomposite, especially its strength. The grafting of nanoparticle surfaces with suitable functional groups can provide improved dispersion and stronger interfacial bonding, improving the fracture resistance of the nanocomposite. In this study, calcium-deficient nanohydroxyapatite (nHA) particles were functionalized with an amino acid-based urethane methacrylate (lysine urethane methacrylate, LUM) and subsequently reacted with hydroxyethyl methacrylate. We mixed these functionalized nHA particles with resin, composed of methacrylated acrylated epoxidized soybean oil, methacrylated isosorbide, and triethylene glycol dimethacrylate, and 3D-printed nanocomposites using masked stereolithography. We hypothesized that the functionalized nanoparticles would enhance the mechanical performance of the 3D-printed nanocomposites due to the greater dispersion and stronger interface. Flexural, tensile, compression and Mode-I fracture toughness test specimens were fabricated using a mSLA printer and tested following ASTM standards. The LUM functionalization of nHA improved the dispersion and increased the viscosity of the uncured nanocomposite ink. The flexural fracture strength, yield strength, and mode-I fracture toughness values were increased by 10%, 30%, and 11%, respectively. The LUM improved the strength and fracture toughness by providing a stronger, more stable interface, resisting debonding between the matrix and particles, allowing for greater plastic deformation.纳米颗粒在聚合物基体中的聚集 会大大降低聚合物纳米复合材料的机械性能,尤其是其强度。通过在纳米粒子表面接枝合适的官能团,可以改善纳米复合材料的分散性,增强界面键合,从而提高纳米复合材料的抗断裂性能。在这项研究中,缺钙的纳米羟基磷灰石(nHA)颗粒被氨基酸基甲基丙烯酸氨基酯(赖氨酸甲基丙烯酸氨基酯,LUM)功能化,随后与甲基丙烯酸羟乙酯反应。我们将这些功能化的nHA颗粒与树脂混合,树脂由甲基丙烯酸酯、甲基丙烯酸酯环氧大豆油、甲基丙烯酸酯异山梨酯和三聚乙二醇二甲基丙烯酸酯组成,并使用屏蔽立体光刻技术3d打印纳米复合材料。我们假设功能化的纳米颗粒由于更大的分散性和更强的界面而增强了3d打印纳米复合材料的力学性能。使用mSLA打印机制作弯曲、拉伸、压缩和i型断裂韧性试样,并按照ASTM标准进行测试。nHA的LUM功能化改善了未固化纳米复合油墨的分散性,提高了其粘度。弯曲断裂强度、屈服强度和i型断裂韧性值分别提高了10%、30%和11%。LUM通过提供更强、更稳定的界面,抵抗基体和颗粒之间的脱粘,从而提高了强度和断裂韧性,允许更大的塑性变形。Three-dimensional woven structural electromagnetic composite metamaterial with lightweight, anti-delaminate and in-phase reflection propertiesWuzhou Li, Kun Zhang, Rui Pei, Fujun Xudoi:10.1016/j.compscitech.2024.110708 三维编织结构电磁复合超材料,具有轻质、抗分层、同相反射等特性Electromagnetic metamaterials are capable of tuning or controlling the transmission of the electromagnetic waves to realize high-performance microwave devices. However, the poor mechanical properties caused by the multi-layer structure limited its wide applications, especially in aircraft, satellites or high-speed vehicles. In this study, an electromagnetic metamaterial with in-phase reflection property was integrated into the three-dimensional (3D) woven composite to achieve the combination of unique electromagnetic properties and excellent mechanical properties on multi-functional composites. The 3D electromagnetic composite metamaterial was capable of reflecting electromagnetic waves from the antenna back lobe to the main lobe at 0° phase, resulting in the bandwidth of the test antenna increased from 0.6 GHz to 1.2 GHz, and the gain increased from 2.8 dB to 4.8 dB, an increase of 71.4%. Owing to the tight physical bonding of binder yarn, 3D electromagnetic composite metamaterial exhibited excellent anti-delaminate performance and stable electromagnetic properties in 28 J impact. The impact damage threshold energy of the 3D electromagnetic composite metamaterial was significantly increased from 10 J to 30 J.电磁超材料能够调节或控制电磁波的传输,从而实现高性能的微波器件。然而,由于多层结构导致的力学性能差,限制了其广泛应用,特别是在飞机、卫星或高速车辆上。本研究将一种具有同相反射特性的电磁超材料集成到三维编织复合材料中,实现了多功能复合材料独特的电磁性能与优异的力学性能的结合。三维电磁复合超材料能够在0°相位将天线后瓣的电磁波反射到主瓣,使测试天线的带宽从0.6 GHz提高到1.2 GHz,增益从2.8 dB提高到4.8 dB,提高了71.4%。由于粘结纱的紧密物理结合,三维电磁复合超材料在28j冲击下表现出优异的抗分层性能和稳定的电磁性能。三维电磁复合超材料的冲击损伤阈值能量由10 J显著提高到30 J。来源:复合材料力学仿真Composites FEM

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