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【新文速递】2024年9月9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,International Journal of Plasticity 1 篇,Thin-Walled Structures 4 篇

International Journal of Solids and Structures

Elastic wave propagation in cubic non-centrosymmetric and chiral architectured materials: Insights from strain gradient elasticity

G. Rosi, N. Auffray, C. Combescure

doi:10.1016/j.ijsolstr.2024.113059

弹性波在立方非中心对称和手性结构材料中的传播:来自应变梯度弹性的见解

In this paper, we investigate wave propagation in cubic periodic architectured materials. We analyse three different types of unit cells, with distinct symmetries (centrosymmetric, non-centrosymmetric chiral and non-centrosymmetric achiral) with the aim of investigating the consequences of such symmetries on the elastodynamic behaviour of the architectured material. To this end, numerical simulations are performed on unit cells representative of the three types, to extract phase velocities and polarisations of waves along different directions. It is shown that some unconventional couplings between the different eigensolutions give rise to circular or elliptically polarised waves, associated with dispersive effects (acoustical activity). Subsequently, a theoretical analysis using a generalised equivalent continuum model (strain gradient elasticity) is performed to analyse these results and unveil the links between the symmetries of the architecture and the macroscopic elastodynamic behaviour. Indeed, it is shown that strain gradient elasticity is able to discriminate between the three symmetry classes, that are seen as equivalent by a classic continuum theory.

本文研究了波在三次周期结构材料中的传播。我们分析了三种不同类型的单体细胞,具有不同的对称性(中心对称、非中心对称手性和非中心对称非手性),目的是研究这种对称性对结构材料弹性动力学行为的影响。为此,在具有代表性的三种类型的单元胞上进行了数值模拟,以提取波沿不同方向的相速度和极化。结果表明,不同特征解之间的一些非常规耦合会产生与色散效应(声学活动)相关的圆形或椭圆形极化波。随后,使用广义等效连续体模型(应变梯度弹性)进行理论分析,以分析这些结果,并揭示结构对称性与宏观弹性动力学行为之间的联系。事实上,它表明应变梯度弹性能够区分三种对称类,这被看作是等效的经典连续统理论。


Journal of the Mechanics and Physics of Solids

Self-consistent solution of the Frank-Bilby equation for interfaces containing disconnections

David B. Gordon, Ryan B. Sills

doi:10.1016/j.jmps.2024.105845

含断路界面的Frank-Bilby方程的自洽解

The quantized Frank-Bilby equation can be used to identify interfacial line defect array configurations which relax the misorientation and/or misfit of a coherent crystalline interface. These line defect arrays may be comprised of dislocations and/or disconnections, which are interfacial steps with dislocation character. When an interface contains disconnections, solution of the quantized Frank-Bilby equation is complicated by the fact that the habit plane orientation is not known in advance because it depends on the unknown spacing of the disconnection array. We present a root-finding-based method for addressing this issue, enabling a self-consistent solution for arbitrary defect content. Our method has been implemented in an open-source code which enumerates all possible solutions given a list of candidate line defects. Two cases are presented employing the code: a misoriented FCC twin boundary and an FCC/BCC phase boundary with the Nishiyama-Wasserman orientation relationship. Both cases exhibit more than 10,000 solutions to the Frank-Bilby equation, with several hundred solutions categorized as “low energy” and thus plausible configurations for the actual interface. The resulting set of solutions can be utilized to predict and understand the properties of a given interface.

量子化的Frank-Bilby方程可以用来识别界面线缺陷阵列构型,从而缓解相干晶体界面的取向错误和/或失配。这些线缺陷阵列可以由位错和/或断开组成,这是具有位错特征的界面步骤。当界面包含断线时,由于习惯面方向取决于断线阵列的未知间距,因此无法预先知道习惯面方向,这使得量子化Frank-Bilby方程的求解变得复杂。我们提出了一种基于根查找的方法来处理这个问题,为任意缺陷内容提供自一致的解决方案。我们的方法已经在一个开放源代码中实现,该代码列举了给定候选行缺陷列表的所有可能的解决方案。给出了两种应用该代码的情况:错误取向的FCC双边界和具有Nishiyama-Wasserman取向关系的FCC/BCC相边界。这两种情况都展示了Frank-Bilby方程的10,000多个解,其中数百个解被归类为“低能量”,因此对于实际界面的合理配置。结果的解决方案集可以用来预测和理解给定接口的属性。


International Journal of Plasticity

A generalised framework for modelling anisotropic creep-ageing deformation and strength evolution of 2xxx aluminium alloys

Xi Wang, Zhusheng Shi, Jianguo Lin

doi:10.1016/j.ijplas.2024.104114

2xxx铝合金各向异性蠕变时效变形和强度演化的一般框架

The 2xxx aluminium alloys are extensively applied in the aerospace industry due to their lightweight and balanced performance characteristics. However, a comprehensive method for modelling both the anisotropic creep deformation and strengthening behaviour in creep age forming (CAF) for 2xxx aluminium alloys remains lacking. This paper presents a generalised framework for establishing constitutive models capable of describing the anisotropic creep deformation coupled with the microstructure and material strength evolutions during creep-ageing of both the original and the pre-deformed 2xxx series Al alloys. This framework extends the rolling direction-based material model to anisotropic scenarios at varying angles between the loading and rolling directions, by employing the non-uniform rational B-splines (NURBS). The details about the anisotropic model calibration and numerical simulation implementation are demonstrated. The feasibility of this method was verified by its application to various 2xxx series aluminium alloys with or without pre-deformation, through constitutive modelling and numerical simulation, with satisfactory agreements between prediction and experimental data. For the first time, the proposed framework provides a generalised routine for establishing anisotropic creep-ageing models for various 2xxx aluminium alloys.

2xxx铝合金由于其轻质和平衡的性能特点而广泛应用于航空航天工业。然而,对于2xxx铝合金的各向异性蠕变变形和蠕变时效成形(CAF)强化行为的综合建模方法仍然缺乏。本文提出了建立本构模型的广义框架,该模型能够描述原始和预变形2xxx系列铝合金在蠕变时效过程中的各向异性蠕变变形、微观组织和材料强度演变。该框架通过采用非均匀有理b样条(NURBS),将基于轧制方向的材料模型扩展到加载方向和轧制方向之间不同角度的各向异性场景。详细介绍了各向异性模型的标定和数值模拟实现。通过本构建模和数值模拟,将该方法应用于预变形和不预变形的各种2xxx系列铝合金,验证了该方法的可行性,预测结果与实验数据吻合良好。提出的框架首次为建立各种2xxx铝合金的各向异性蠕变时效模型提供了一个通用的程序。


Thin-Walled Structures

Delamination free forming of novel high interface strength metal-polymer laminates

R.K. Naik, S.K. Panda, V. Racherla

doi:10.1016/j.tws.2024.112416

新型高界面强度金属-聚合物层压板的无分层成形

A new class of metal-polymer-laminates, fabricated using wire mesh and “steel-chips” interlayer, is shown to have significantly high interface strength. A finite element model, calibrated using tensile, lap shear, and peel tests, is used to predict the deformation and failure of the laminates. Formability of the developed laminates is studied using the limiting-dome-height tests. The metal-polymer-laminates do not delaminate in any of the tests. A complete shift of forming-limit-curve towards biaxial-tension region is observed in strain-based forming limit diagram for the polymer side. Strain-path independent forming-limits are plotted in stress space, to negative the effect of non-proportional strain histories.

一种新型的金属-聚合物层压板,由金属丝网和“钢屑”夹层制成,具有显著的高界面强度。使用拉伸、搭接剪切和剥离试验校准的有限元模型,用于预测层压板的变形和失效。利用极限顶高试验对所研制的层合板的成形性进行了研究。金属聚合物层压板在任何测试中都不会分层。在基于应变的聚合物侧成形极限图中,成形极限曲线完全向双轴拉伸区移动。在应力空间中绘制了与应变路径无关的形成极限,以消除非比例应变历史的影响。


Regression-classification ensemble machine learning model for loading capacity and bucking mode prediction of cold-formed steel built-up I-section columns

Yan Lu, Bin Wu, Wenchao Li, Tianhua Zhou, Yanchun Li

doi:10.1016/j.tws.2024.112427

冷弯型钢组合截面柱承载力及屈曲模态预测的回归分类集成机器学习模型

This paper presents a regression-classification ensemble machine learning (ML) model for load capacity and, in particular, buckling mode prediction with respect to cold-formed steel (CFS) I-section columns. The ML model comprises two sub-models, including the regression sub-model for load capacity prediction and the classification sub-model for buckling mode prediction. A total of 541 experimental and numerical data for CFS built-up I-section columns with varies geometric dimensions, material properties and buckling modes were collected from the literature to construct a dataset. To improve the accuracy and the explainability of the ML model on relative small-scale dataset, physical information-enhanced features based on the knowledge of the direct strength method were adopted as the input features of the ML model, including the yield strength, the elastic local buckling load, the elastic distortional buckling load and the elastic global buckling load, instead of directly using the parameters of geometric dimensions and material properties as the input features. The appropriateness of seven classical machine learning algorithms was compared, namely Decision Tree (DT), Random Forest (RF), Support Vector Machine (SVM), K-Nearest Neighbour (KNN), Adaptive Boosting (ADA), Extreme Gradient Boosting (XG), and Categorical Boosting (CB). The statistical analysis showed that the XG algorithm had the highest level of accuracy for both loading capacity and buckling mode prediction. In addition, the explainability analysis indicated that the developed ML model successfully learned the mechanical characteristic of CFS built-up I-section columns. Finally, the developed ML model was further compared with the existing codified method in the literature. The comparison results indicated that the developed ML model can significantly improve the level of accuracy for loading capacity and buckling mode prediction, which provides a promising alternative choice for the design of CFS built-up I-section columns

本文提出了一个回归分类集成机器学习(ML)模型,用于承载能力,特别是关于冷弯型钢(CFS) i型截面柱的屈曲模式预测。ML模型包括两个子模型,分别是用于载荷能力预测的回归子模型和用于屈曲模态预测的分类子模型。本文收集了541个不同几何尺寸、材料性能和屈曲模态的CFS组合式工字截面柱的实验和数值数据,构建了数据集。为了提高ML模型在相对小尺度数据集上的准确性和可解释性,采用基于直接强度法知识的物理信息增强特征作为ML模型的输入特征,包括屈服强度、弹性局部屈曲载荷、弹性畸变屈曲载荷和弹性全局屈曲载荷,而不是直接使用几何尺寸和材料性能参数作为ML模型的输入特征。比较了决策树(DT)、随机森林(RF)、支持向量机(SVM)、k近邻(KNN)、自适应增强(ADA)、极端梯度增强(XG)和分类增强(CB)等7种经典机器学习算法的适用性。统计分析表明,XG算法对载荷能力和屈曲模态的预测精度最高。此外,可解释性分析表明,所建立的ML模型成功地学习了CFS组合工字截面柱的力学特性。最后,将所建立的机器学习模型与文献中已有的编码方法进行了进一步的比较。结果表明,所建立的ML模型能显著提高承载能力和屈曲模态预测的精度水平,为组合式工字截面柱的设计提供了一种有希望的替代选择


A CO-HSDT isogeometric analysis for free vibration of matrix cracked FG-GPLRC plates coupled with stationary fluid

Wei Chen, Linxin Peng, Bing Sun, Wanruo Chen, Yaochu Fang

doi:10.1016/j.tws.2024.112441

静止流体耦合下FG-GPLRC基体裂纹板自由振动的CO-HSDT等几何分析

This paper for the first time proposes an efficiently C0-higer order shear deformation theory (HSDT) and isogeometric analysis (IGA) for the free vibration analysis of matrix cracked functionally graphene nanoplatelets reinforced composite (FG-GPLRC) plate coupled with stationary fluid. This case represents essential components of sophisticated structures utilized in industries such as shipbuilding, nuclear, marine, and naval. The properties of the four GPLs distributions of FG-GPLRC are evaluated by using a combination of the modified Halpin-Tsai micromechanics model and the rule of mixtures, while the degraded stiffness of cracked layers is predicted by the self-consistent micromechanical (SCM) model. The fluid is assumed to be homogeneous, inviscid, incompressible and irrotational, so the free-surface waves and hydrostatic pressure effects on structures are neglected. The governing equation of motion is derived by the Hamilton's principle, where three different fluid-plate interaction systems are taken into consideration. After validating the proposed method against existing literature, the effect of various parameters such as crack density, interaction boundary conditions (IBC), fluid level, GPLs distribution pattern, total number of layers, and geometric parameter on the free vibration of matrix cracked FG-GPLRC plate are investigated. It is believed that the finding in this paper may be helpful for the accurate design and analysis of matrix cracked FG-GPLRC plate submerged in fluid.

本文首次提出了一种高效的c0 -高阶剪切变形理论(HSDT)和等几何分析(IGA),用于分析固定流体耦合下的基体裂纹功能石墨烯纳米片增强复合材料(FG-GPLRC)板的自由振动。这个案例代表了在造船、核、海洋和海军等行业中使用的复杂结构的重要组成部分。采用改进的Halpin-Tsai细观力学模型和混合规律对FG-GPLRC的四种GPLs分布特性进行了评价,并采用自洽细观力学模型对裂纹层的退化刚度进行了预测。假设流体是均匀的、无粘的、不可压缩的和无旋转的,因此忽略了自由表面波和静水压力对结构的影响。在考虑了三种不同的流-板相互作用系统的情况下,利用汉密尔顿原理推导了运动控制方程。在对照已有文献验证该方法的基础上,研究了裂纹密度、相互作用边界条件(IBC)、流体水平、gpl分布模式、层数和几何参数等参数对基体裂纹FG-GPLRC板自由振动的影响。本文的研究结果可为基体裂纹FG-GPLRC板在流体中的精确设计和分析提供参考。


Impact Behavior of Advanced Films under Micro- and Nano-scales: A Review

Yujie Cheng, Jinlei Dong, Kailu Xiao, Minqiang Jiang, Chenguang Huang, Xianqian Wu

doi:10.1016/j.tws.2024.112443

先进薄膜在微纳米尺度下的冲击行为研究进展

High-performance materials with excellent impact resistance are of fundamental importance in impact protective engineering. With the development of experimental facilities and numerical simulations at the micro- and nano-scales in recent years, some advanced films are found to show extraordinary energy absorption capacities, showing great promise as ideal bulletproof materials. In this paper, we review the dynamic behavior of four typical types of advanced films that are promising candidates as bulletproof materials subject to supersonic micro- and nano-ballistic impact. Their specific energy absorptions are summarized and the corresponding energy dissipation mechanisms are provided. The size effects are discussed. Some feasible design strategies for improving the impact resistance of the films are also introduced. It should be noted the current ballistic impact standards such as the NIJ standard do not apply to nanofilms. Based on LIPIT and MD simulations, the protective properties of the nanofilms have been obtained. We think that if the materials show high SEAs under micro- and nano-ballistic impact, they are expected to exhibit high impact resistance at the macro scale.

具有优异抗冲击性能的高性能材料是冲击防护工程的基础。近年来,随着实验设备的发展和在微纳米尺度上的数值模拟,一些先进的薄膜显示出非凡的能量吸收能力,有望成为理想的防弹材料。在本文中,我们回顾了四种典型的有希望成为防弹材料的先进薄膜在超音速微纳米弹道冲击下的动态行为。总结了它们的比能量吸收,并给出了相应的能量耗散机制。讨论了尺寸效应。介绍了提高薄膜抗冲击性能的可行设计策略。应该指出的是,目前的弹道冲击标准,如NIJ标准,并不适用于纳米膜。基于LIPIT和MD模拟,得到了纳米膜的保护性能。我们认为,如果材料在微观和纳米弹道冲击下表现出较高的SEAs,则有望在宏观尺度上表现出较高的抗冲击性。



来源:复合材料力学仿真Composites FEM
ACTMechanicalSystemDeformSTEPS振动复合材料通用航空航天海洋声学裂纹理论材料控制试验
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首次发布时间:2024-11-21
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【新文速递】2024年9月11日复合材料SCI期刊最新文章

今日更新:Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 4 篇,Composites Science and Technology 1 篇Composites Part A: Applied Science and ManufacturingVibroscope method for determination of cross-sectional area of glass and carbon fibres– Theory and further developmentBo Madsen, Jan Høgsberg, Hans Lilholtdoi:10.1016/j.compositesa.2024.108446 玻璃纤维和碳纤维横截面积测定用振动镜方法。理论和进一步发展Accurate determination of cross-sectional area of glass and carbon fibres by the vibroscope method is examined. Complete derivations of the central frequency solutions are presented, to make these derivations accessible in modern scientific literature. The effect of non-zero bending stiffness is included. The influence of shape of fibre cross-sectional area is analysed. Only small deviations in cross-sectional areas are found due to fibre shape, allowing for the use of the vibroscope method for fibres with non-circular cross-sectional areas. Two correction factors are introduced for the effect of volume change and area change of a tensioned fibre, allowing determination of the cross-sectional area of the non-tensioned fibre. A model plot of the vibroscope equation is presented, showing the numerical effect of the corrections on the fibre cross-sectional area depending on the applied tension force. The relations shown by the model plot have implications for the experimental settings of the vibroscope method.研究了用振镜法精确测定玻璃纤维和碳纤维的横截面积。给出了中心频率解的完整推导,使这些推导在现代科学文献中易于理解。考虑了非零弯曲刚度的影响。分析了纤维截面面积形状的影响。由于纤维形状的原因,截面积只有很小的偏差,允许对非圆形截面积的纤维使用测振仪方法。引入了两个校正因子对拉伸纤维的体积变化和面积变化的影响,从而可以确定未拉伸纤维的横截面积。给出了测振器方程的模型图,显示了根据施加的张力,修正对纤维横截面积的数值影响。模型图所示的关系对测振仪方法的实验设置具有启示意义。Composites Part B: EngineeringEnhancing toughness in cement-based composites: unraveling the composite effect mechanisms of polymers and fibers through physic testing and molecular dynamics simulationsShi-Wei Zhang, Ru Wang, Jiao-Long Zhang, Yong Yuandoi:10.1016/j.compositesb.2024.111827增强水泥基复合材料的韧性:通过物理测试和分子动力学模拟揭示聚合物和纤维的复合效应机制To reveal the toughening mechanism of polymers and fibers in composite applications, a combination of physical tests (uniaxial compression, flexural fracture, single fiber pull-out, scanning electron microscopy, and X-ray diffraction (XRD)) and molecular dynamics simulations have been carried out. Three polymers, i.e. ethylene-vinyl acetate copolymer (EVA), styrene-acrylate copolymer (SAE), and styrene-butadiene copolymer (SB), and two fibers, i.e. polypropylene fiber (PP) and polyvinyl alcohol fiber (PVA) are considered. Their composite effect mechanisms are explained in the viewpoint of three scales. At the macro-scale, the pull-out tests of single fiber show that the polymer increased the equivalent bond strength between the fiber and the mortar matrix. At micro-scale, it was observed from the SEM experiments that the fiber and polymer film inhibited the crack extension at different scales, besides the polymer could absorb on the fiber surface to improve the interfacial transition zone (ITZ) density around the fiber and increase the roughness of the fiber surface. At nano-scale, MD simulations demonstrate that three polymers facilitated the bond strength between PP fiber and C-S-H at the nano-scale, mainly because of the formation of Ca-O coordination bond and H-bonds between the polymers and C-S-H, and the presence of van der Waals forces between the polymers and PP fiber. However, SAE facilitated the bonding between the PVA fibers and the C-S-H, which originated from the coordination bonds formed between Ca ions on the surface of SAE and O atoms in PVA. In addition, the large number of H-bonds formed between SAE and PVA.为了揭示聚合物和纤维在复合材料应用中的增韧机理,进行了物理测试(单轴压缩、弯曲断裂、单纤维拉出、扫描电子显微镜和x射线衍射(XRD))和分子动力学模拟。考虑了三种聚合物,即乙烯-醋酸乙烯共聚物(EVA)、苯乙烯-丙烯酸酯共聚物(SAE)和苯乙烯-丁二烯共聚物(SB)和两种纤维,即聚丙烯纤维(PP)和聚乙烯醇纤维(PVA)。从三个尺度的角度解释了它们的复合效应机制。在宏观尺度上,单纤维的拉拔试验表明,聚合物提高了纤维与砂浆基体之间的等效粘结强度。在微观尺度上,SEM实验观察到,纤维和聚合物膜在不同尺度上抑制了裂纹的扩展,聚合物在纤维表面的吸附作用提高了纤维周围界面过渡区(ITZ)密度,增加了纤维表面的粗糙度。在纳米尺度上,MD模拟表明,三种聚合物在纳米尺度上促进了PP纤维与C-S-H之间的键合强度,主要是由于聚合物与C-S-H之间形成了Ca-O配位键和h键,以及聚合物与PP纤维之间存在范德华力。然而,SAE促进了PVA纤维与C-S-H之间的键合,这源于SAE表面的Ca离子与PVA中的O原子之间形成的配位键。此外,SAE与PVA之间形成了大量的氢键。In-situ formed silicon oxycarbide nanowires into porous SiC(rGO) PDCs enable balanced enhancement of robustness and thermal managementWenyan Huang, Jiahao Liang, Kaiqi Chen, Ying Yu, Yeqi Zhu, Junhui Li, Cheng Pan, Yipeng Guo, Siqi Lan, Rongqian Yaodoi:10.1016/j.compositesb.2024.111828 原位形成的碳化硅纳米线可用于多孔碳化硅(rGO) pdc,可平衡增强稳健性和热管理With ongoing development of rocket combustion and hypersonic vehicles, urgent needs are created on thermal structures, protection and thermal insulating materials, particularly balanced enhancement of mechanical and antioxidant properties. Herein, we propose a design strategy to construct continuous in-situ formed SiOC nanowires (SiOCnws)-toughened self-healing SiOx coatings into porous SiC(rGO) PDCs. The key production technique is re-pyrolyzing coassembled flexible precursors/SiC(rGO)p/graphite blends, followed by decarbonization and silica sol impregnation-sintering (SIS) process. Well-distributed hierarchical pores are built to heighten thermal insulation properties by the integrated decarburization of graphite coupled with free carbon. High-yield SiOCnws, with high surface activity, are first cultivated via graphite-assisted vapor-solid (VS) mechanism without transition metal catalysts. They interconnect to form intricate 3D meshwork by graphite-assisted melt-spinning and have good compatibility with ceramic matrix and SiOx coatings by carbothermal reaction. Hierarchically porous SiOCnws/SiC(rGO)40% PDCs after once SIS exhibit favorable thermal conductivity of 0.27 W·m-1·K-1 and exceptional high robustness (compressive strength: 39.02 MPa, hardness: 10.27 GPa). Such composites display low reflection loss of -48.14 dB at 11.22 GHz and even good structural stability at about 1300 °C as burned by a butane blowtorch for 3600 s, shedding light on competitive components for uses in thermal protection fields.随着火箭燃烧和高超音速飞行器的不断发展,对热结构、保护和隔热材料提出了迫切的需求,尤其是在提高机械性能和抗氧化性能方面。在此,我们提出了一种在多孔 SiC(rGO)PDC 中构建连续原位成型 SiOC 纳米线(SiOCnws)-增韧自修复 SiOx 涂层的设计策略。关键的生产技术是重新热解共组装柔性前驱体/SiC(rGO)p/石墨混合物,然后进行脱碳和硅溶胶浸渍-烧结(SIS)工艺。通过对石墨和游离碳进行综合脱碳,形成了分布均匀的分层孔隙,从而提高了隔热性能。首先在不使用过渡金属催化剂的情况下,通过石墨辅助气固(VS)机制培养出具有高表面活性的高产 SiOCnws。它们通过石墨辅助熔融纺丝相互连接形成复杂的三维网状结构,并通过碳热反应与陶瓷基体和氧化硅涂层具有良好的兼容性。经过一次 SIS 后的分层多孔 SiOCnws/SiC(rGO)40%PDC 具有 0.27 W-m-1-K-1 的良好热导率和超高的坚固性(抗压强度:39.02 MPa,硬度:10.27 GPa)。这种复合材料在 11.22 GHz 频率下的反射损耗低至 -48.14 dB,甚至在丁烷喷灯灼烧约 1300 °C 3600 秒后仍具有良好的结构稳定性,为热保护领域提供了具有竞争力的元件。Electrical resistance based residual strength prediction method for SiC/SiC mini-composites after stress-free oxidationBeichen Xue, Guoqiang Yu, Chuyang Xie, Wenbing Ma, Jiaming Li, Xiguang Gao, Fang Wang, Yingdong Songdoi:10.1016/j.compositesb.2024.111832基于电阻的SiC/SiC微复合材料无应力氧化残余强度预测方法A stress-free oxidation model considering the microstructural characteristics of SiC/SiC mini-composites was proposed based on the electrical resistance change before and after oxidation. The relationship between the electrical resistance and the thickness of the internal fiber oxide layer was established. The stress-free oxidation tests were carried out at different temperatures for different oxidation times. The results of the oxide layer thickness calculated by the model agree well with those of the SEM observation. Based on the microstructure of tensile fracture after oxidation, the residual strength model of SiC/SiC mini-composites was proposed. The residual strength of the specimens after stress-free oxidation was calculated based on the oxide layer thickness obtained from the model. The error between the calculated and experimental results is within 14.48%.基于氧化前后的电阻变化,提出了一种考虑SiC/SiC微型复合材料微观结构特征的无应力氧化模型。建立了电阻与内部氧化纤维层厚度之间的关系。在不同温度、不同氧化时间下进行了无应力氧化试验。模型计算的氧化层厚度与SEM观测结果吻合较好。基于氧化后拉伸断裂的微观组织,提出了SiC/SiC微型复合材料的残余强度模型。根据模型得到的氧化层厚度计算试样无应力氧化后的残余强度。计算结果与实验结果的误差在14.48%以内。Hierarchical microstructure design of multifunctional soft collagen-incorporated 3D hard polyetherketoneketone scaffolds for augmented bone regenerationHuanhuan Liu, Xiaoyin Liu, Taiqing Liu, Sihan Rao, ManLin Sun, YuSen Shui, Tian Luo, Yuwei Zhao, Haiyang Yudoi:10.1016/j.compositesb.2024.111833 多功能软胶原复合三维硬聚醚酮增强骨再生支架的分层结构设计Implant-associated infections and insufficient osseointegration are still great challenges in clinical load-bearing applications. Exploiting the antibacterial effects and immunomodulatory properties of biomaterials has garnered substantial attention. Inspired by structural and functional cues in bone regeneration, a universal approach was proposed in which a hydroxyapatite (HAp) coating was built on 3D printed polyetherketoneketone (PEKK) scaffold, and a bioactive component-loaded soft mineralized collagen hydrogel was incorporated into 3D hard PEKK scaffold. While the PEKK scaffold exhibited exceptional mechanical performance, in vitro and in vivo data confirmed that exosomes derived from rat bone marrow mesenchyme stem cells (rBMSCs) loaded on collagen hydrogel facilitate efficient osteoimmunomodulation of the PEKK-based scaffold (denoted as the PEKK-HAp-Col/Exo scaffold). Additionally, vancomycin-loaded nanoparticles cross-linked with collagen hydrogel endowed the PEKK-based scaffold (denoted as the PEKK-HAp-Col/Van scaffold) with enhanced antibacterial effects. Overall, this study not only sheds light on the significance of exosomes in the osteoimmunomodulation of an implant but also presents a universal material–structure–function integrated strategy to fabricate multifunctional scaffolds with a soft-hard hybrid structure for clinical large-scale bone defect repair.种植体相关感染和骨整合不足仍然是临床承重应用的巨大挑战。利用生物材料的抗菌作用和免疫调节特性已经引起了人们的广泛关注。受骨再生的结构和功能线索的启发,提出了一种通用的方法,即在3D打印聚醚酮酮(PEKK)支架上构建羟基磷灰石(HAp)涂层,并将生物活性成分负载的软矿化胶原水凝胶结合到3D硬PEKK支架中。虽然PEKK支架表现出优异的机械性能,但体外和体内数据证实,胶原水凝胶负载的大鼠骨髓间充质干细胞(rBMSCs)衍生的外泌体促进了基于PEKK的支架(称为PEKK- hap - col /Exo支架)的有效骨免疫调节。此外,负载万古霉素的纳米颗粒与胶原水凝胶交联,使pekk支架(称为PEKK-HAp-Col/Van支架)具有增强的抗菌作用。总的来说,本研究不仅揭示了外泌体在种植体骨免疫调节中的重要性,而且提出了一种通用的材料-结构-功能集成策略,用于临床大规模骨缺损修复的软硬混合结构多功能支架。Composites Science and TechnologyInvestigation of buckling instabilities in fiber-reinforced DEAsStefania Konstantinidi, Markus Koenigsdorff, Thomas Martinez, Amine Benouhiba, Johannes Mersch, Yoan Civet, Gerald Gerlach, Yves Perriarddoi:10.1016/j.compscitech.2024.110849 纤维增强dea的屈曲不稳定性研究Artificial muscles, designed to replicate the movements of natural biological muscles, hold significant promise in the fields of robotics and prosthetics. Recent advancements have led to the development of fiber-reinforced actuators, drawing inspiration from biological tissues. Dielectric elastomer actuators (DEAs) are a type of electroactive artificial muscle. It is possible to enhance the uni-axial deformation of DEAs by constraining and applying pre-stretch on the actuator membrane. This can be achieved through uni-directional fibers bonded to the DEA that lead to transversely isotropic properties. However, combining membrane pre-stretch and fiber reinforcement may lead to instabilities such as fiber buckling due to the compressive load of the pre-stretched membrane or due to wrinkling during actuation. Understanding these instabilities is crucial as they can significantly impact the performance. A novel model taking into consideration these instabilities is established and experimentally validated. By calculating the force in the fiber direction, the buckling profile such as the wavelength and amplitude can be predicted. The validation of the model presented along with an extensive experimental investigation allow for a comprehensive analysis to explore the impact of fiber buckling on the performance and the force of uni-axial DEAs.人造肌肉是为了复 制自然生物肌肉的运动而设计的,在机器人和假肢领域有着重要的前景。最近的进步导致了纤维增强致动器的发展,从生物组织中汲取灵感。介电弹性体致动器是一种电活性人造肌肉。在致动器薄膜上施加预拉伸和约束可以增强致动器的单轴变形。这可以通过与DEA结合的单向光纤实现,从而获得横向各向同性。然而,将膜预拉伸与纤维增强相结合可能会导致不稳定,如由于预拉伸膜的压缩载荷或由于驱动过程中的起皱而导致纤维屈曲。理解这些不稳定性至关重要,因为它们会显著影响性能。建立了考虑这些不稳定性的新模型,并进行了实验验证。通过计算光纤方向上的力,可以预测光纤的屈曲曲线,如波长和振幅。该模型的验证以及广泛的实验研究允许对纤维屈曲对单轴dea性能和力的影响进行全面分析。来源:复合材料力学仿真Composites FEM

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