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【新文速递】2024年6月15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 5 篇

International Journal of Solids and Structures

Harnessing unconventional buckling of tube origami metamaterials based on Kresling pattern

Emilio Turco, Emilio Barchiesi, Andrea Causin, Francesco dell’Isola, Margherita Solci

doi:10.1016/j.ijsolstr.2024.112925

利用基于克瑞斯林模式的管状折纸超材料的非常规屈曲

Kresling tube metamaterials are well known to exhibit a chirality-dependent exotic mechanical feature: a shortening or lengthening in the direction of the tube’s axis produces a relative rotation of the two polygonal bases of the tube. This property can be easily grasped by fabricating a single-storey Kresling tube using cardboard. What has not been stressed much, if not even recognized, in the literature is the fact that such a mechanical feature is not depending only on the (chiral) geometrical pattern and unaffected by the in-plane/bending stiffness of facets and the creases’ resistance to folding. Assuming to neglect the bending stiffness of facets, in the present contribution we prove, through some numerical simulations based on a discrete model taking into account inertial terms, that only when the in-plane-to-folding stiffness ratio is large the Kresling tube exhibits the aforementioned exotic feature as described in the literature. We also prove that a low in-plane-to-folding stiffness ratio reveals: (i) an unconventional buckling mode, both for axial shortening and lengthening, which resembles the mechanism of a camera diaphragm; (ii) a kind of auxetic behaviour, i.e. a stenosis in a shortening test.

众所周知,克瑞斯林管超材料表现出一种与手性相关的奇异机械特性:在管轴方向上的缩短或延长会使管子的两个多边形基部产生相对旋转。利用硬纸板制作单层克雷斯林管,就能轻松掌握这一特性。文献中没有过多强调,甚至没有认识到的事实是,这种机械特性并不仅仅取决于(手性)几何图案,也不受切面的平面内/弯曲刚度和折痕抗折能力的影响。在本论文中,我们假定忽略刻面的弯曲刚度,通过一些基于离散模型的数值模拟并考虑惯性项,证明只有当平面内与折叠刚度比很大时,克雷斯林管才会表现出文献中描述的上述奇特特征。我们还证明,平面内与折叠刚度比小的情况下会出现:(i) 非传统的屈曲模式,无论是轴向缩短还是拉长,都类似于照相机膜片的机理;(ii) 一种辅助行为,即在缩短试验中出现狭窄。


Journal of the Mechanics and Physics of Solids

Derivation, characterization, and application of complete orthonormal sequences for representing general three-dimensional states of residual stress

Sankalp Tiwari, Eliot Fried

doi:10.1016/j.jmps.2024.105729

用于表示一般三维残余应力状态的完整正交序列的推导、表征和应用

Residual stresses are self-equilibrated stresses on unloaded bodies. Owing to their complex origins, it is useful to develop functions that can be linearly combined to represent any sufficiently regular residual stress field. In this work, we develop orthonormal sequences that span the set of all square-integrable residual stress fields on a given three-dimensional region. These sequences are obtained by extremizing the most general quadratic, positive-definite functional of the stress gradient on the set of all sufficiently regular residual stress fields subject to a prescribed normalization condition; each such functional yields a sequence. For the special case where the sixth-order coefficient tensor in the functional is homogeneous and isotropic and the fourth-order coefficient tensor in the normalization condition is proportional to the identity tensor, we obtain a three-parameter subfamily of sequences. Upon a suitable parameter normalization, we find that the viable parameter space corresponds to a semi-infinite strip. For a further specialized spherically symmetric case, we obtain analytical expressions for the sequences and the associated Lagrange multipliers. Remarkably, these sequences change little across the entire parameter strip. To illustrate the applicability of our theoretical findings, we employ three such spherically symmetric sequences to accurately approximate two standard residual stress fields. Our work opens avenues for future exploration into the implications of different sequences, achieved by altering both the spatial distribution and the material symmetry class of the coefficient tensors, toward specific objectives.

残余应力是未加载物体上的自平衡应力。由于其复杂的起源,开发可线性组合以表示任何足够规则的残余应力场的函数非常有用。在这项工作中,我们开发了正交序列,它涵盖了给定三维区域上所有可平方积分残余应力场的集 合。这些序列是通过对所有足够规则的残余应力场集 合上的应力梯度的最一般二次正定有限元函数进行极化而得到的,该极化需满足一个规定的归一化条件;每个这样的函数都会产生一个序列。对于函数中的六阶系数张量是均质和各向同性的,而归一化条件中的四阶系数张量与同一张量成比例的特殊情况,我们得到了一个三参数的序列子族。经过适当的参数归一化处理后,我们发现可行的参数空间对应于一个半无限条带。对于更特殊的球面对称情况,我们得到了序列和相关拉格朗日乘数的分析表达式。值得注意的是,这些序列在整个参数带中几乎没有变化。为了说明我们的理论发现的适用性,我们采用了三个这样的球面对称序列来精确逼近两个标准残余应力场。通过改变系数张量的空间分布和材料对称性类别,我们的工作为未来探索不同序列对特定目标的影响开辟了道路。


International Journal of Plasticity

High-cycle and low-cycle fatigue characteristics of multilayered dissimilar titanium alloys

Tianle Li, Wei Fan, Xifeng Li, Huiping Wu, Dayong An, Qi Hu, Jun Chen

doi:10.1016/j.ijplas.2024.104033

多层异种钛合金的高循环和低循环疲劳特性

Multilayered structures of dissimilar titanium alloys can achieve excellent fracture ductility and strength, while their fatigue characteristics especially dislocation networks and twin formation are rarely reported. Heterogeneous microstructures are observed in the multilayered TC4/TB8 alloys, including fine acicular α grains, continuous α layer at prior β grain boundaries (αGB) and β matrix on the TB8 layer, together with equiaxed α grains on the TC4 layer. High-cycle fatigue (HCF) and low-cycle fatigue (LCF) tests show that the initial fatigue damage appears at the αGB/β matrix interfaces on the TB8 layer instead of the boned TC4/TB8 interfaces. Since the stress concentration induced by dislocation pile-up is prone to micro-void formation and crack propagation at the αGB/β interfaces. For LCF, the αGB/β interfaces can not only act as impenetrable barriers and sources of lattice dislocations, but also allow the dislocations cross boundaries during cyclic tension and compression because of the high boundary energy. The formation characteristic of deformation twins that is beneficial for the plastic deformation of α grains in TC4 layer during cyclic strain is investigated. Furthermore, the hexagonal dislocation networks are also found within the equiaxed α grains of TC4 layer after LCF, and the role between interface barrier and slip direction in the formation mechanism is analyzed.

异种钛合金的多层结构可获得优异的断裂延展性和强度,但其疲劳特性,尤其是位错网络和孪晶形成却鲜有报道。在多层 TC4/TB8 合金中观察到了异质微观结构,包括细针状 α 晶粒、先于 β 晶界的连续 α 层(αGB)和 TB8 层上的 β 基体,以及 TC4 层上的等轴 α 晶粒。高循环疲劳(HCF)和低循环疲劳(LCF)试验表明,最初的疲劳损伤出现在 TB8 层上的 αGB/β 基体界面,而不是 TC4/TB8 的骨界面。由于位错堆积引起的应力集中容易在 αGB/β 接口处形成微空洞和裂纹扩展。对于 LCF 而言,αGB/β 界面不仅可以充当不可穿透的屏障和晶格位错源,而且在循环拉伸和压缩过程中,由于高边界能,位错还可以越界。研究了在循环应变过程中有利于 TC4 层中 α 晶粒塑性变形的变形孪晶的形成特征。此外,在 LCF 后,TC4 层等轴 α 晶粒内也发现了六方位错网络,并分析了界面屏障和滑移方向在形成机制中的作用。


Thin-Walled Structures

Seismic behaviour of reusable column base connection with pinned energy dissipators

MA Qi, CHAN Tak-Ming

doi:10.1016/j.tws.2024.112113

带有销钉消能装置的可重复使用柱基连接的抗震性能

A column base connection has been proposed to achieve reusability and self-centring after earthquakes. This proposed connection incorporates simple metallic yielding energy dissipators to effectively absorb seismic energy, while also employing pinned joints to facilitate the restoration of rocking behaviour in the column. To investigate the hysteretic behaviour of this innovative connection, a series of quasi-static tests were conducted on six groups of specimens. Among the parameters explored were the length, width, and limb number of the reduced section, activation angle, and material characteristics of the dissipative plate. During these experiments, the rocking mechanism was successfully demonstrated, and it was observed that the failure mode primarily involved concentrated plastic deformations of the dissipative plates. All of the specimens exhibited exceptional energy dissipation and self-centring capabilities. Furthermore, the repair process simply required the replacement of the damaged dissipative plates, which proved to be advantageous in terms of cost-effectiveness and efficiency. As a result, the repaired specimens regained their load-bearing ability and seismic performance to a comparable level as the original specimens. In the analysis of the test data, the changing patterns of dissipated energy, equivalent viscous damping ratio, and secant stiffness were determined in relation to the increasing target lateral displacement. The effects of various parameters on these aforementioned indexes were also preliminarily investigated. Additionally, based on the design concept, the relationship between moment and rotation angle of the column was described by an idealised curve. Consequently, the moment resistances of all test specimens were calculated, and the predicted results aligned well with the actual test results.

我们提出了一种柱基连接,以实现地震后的可重复使用性和自我集中。这种拟议的连接采用了简单的金属屈服消能装置来有效吸收地震能量,同时还采用了销钉连接来促进恢复柱子的摇晃行为。为了研究这种创新连接的滞后行为,对六组试样进行了一系列准静态试验。试验参数包括缩小截面的长度、宽度和肢数、激活角以及消能板的材料特性。在这些实验中,成功证明了摇摆机制,并观察到破坏模式主要涉及耗能板的集中塑性变形。所有试样都表现出卓越的消能和自聚能能力。此外,修复过程只需更换损坏的耗能板即可,这在成本效益和效率方面具有优势。因此,修复后的试样恢复了承载能力和抗震性能,达到了与原试样相当的水平。在对试验数据进行分析时,确定了随着目标侧向位移的增加,耗散能量、等效粘滞阻尼比和秒刚度的变化规律。还初步研究了各种参数对上述指标的影响。此外,根据设计理念,用理想化的曲线描述了支柱力矩与旋转角度之间的关系。因此,计算了所有试件的抗弯矩能力,预测结果与实际测试结果非常吻合。


Seismic design-assisted-by-testing approach for racks with dissipative baseplates in the cross-aisle direction

Bonaventura Tagliafierro, Rosario Montuori, Ioannis Vayas

doi:10.1016/j.tws.2024.112126

跨通道方向带耗散基板机架的抗震设计辅助测试方法

A design-assisted-by-testing strategy is proposed for the upright frames of adjustable pallet racks. The methodology defines a procedure that aims to locate marked post-elastic behavior at the floor-to-upright connections of lateral resisting frames in the cross-aisle direction. Such connections are intended to enhance the performance of the cross-aisle frames when subjected to dynamic forces in their plane. The chosen baseplateis experimentally tested using monotonic and cyclic protocols at the Steel Structures Laboratory of the National Technical University of Athens (Greece). Then, a numerical model of the baseplate is calibrated using literature parameter definitions and hence validated using physical data. Additionally, the dynamic response of two upright frames is numerically investigated: one with traditional hinge connections and another with dissipative ones. This study indicates that the proposed procedure successfully enhances ductility, resulting in a significant reduction (up to 50%) in upright axial forces compared to the conventional configuration. Finally, the open-source code for ground motion selection, together with its database, is released.

针对可调式托盘货架的直立框架提出了一种设计辅助测试策略。该方法定义了一个程序,旨在确定横向抗侧力框架的地板与直立框架连接处的明显后弹性行为。这种连接的目的是提高跨通道框架在其平面上受到动态力时的性能。希腊雅典国立技术大学钢结构实验室采用单调和循环协议对所选底板进行了实验测试。然后,利用文献中的参数定义对底板的数值模型进行校准,并利用物理数据进行验证。此外,还对两个直立框架的动态响应进行了数值研究:一个采用传统铰链连接,另一个采用耗散连接。研究结果表明,与传统结构相比,建议的程序成功地增强了延展性,使直立轴向力显著减少(最多减少 50%)。最后,发布了用于地面运动选择的开源代码及其数据库。


An adaptive modeling method with a local choice of optimal displacement fields for finite element analysis of structures

Guoqiang Wei, Jeanne Paroissien, Pascal Lardeur, Frédéric Druesne, Marc Oujdene

doi:10.1016/j.tws.2024.112129

结构有限元分析中局部选择最佳位移场的自适应建模方法

In the standard finite element procedure, the user chooses himself which mechanical theory will be used for a given application. To this end, he relies on some rules acquired through experience or some theoretical consideration. But choosing an appropriate theory may be a difficult task when geometry, boundary conditions, loadings, and materials are complex. This paper aims to define an adaptive methodology to identify, in the context of linear static analysis, optimal finite element models from a theory choice point of view. A criterion is defined to choose, in each part of the structure, the relevant mechanical theory: solid, shell or beam. A solid mesh is defined for the whole structure while specific solid-shell or solid-beam approaches are used in shell or beam areas respectively. This avoids the construction of mid-surface or mid-axis geometries from solid ones, which is a complicated task, in particular for industrial applications. Kinematic relations between nodes are imposed to apply the displacement fields of shell or beam theories. This leads to a set of linear equations which are used for eliminating slave degrees of freedom. The methodology proposed can also be interpreted as a model size reduction method, compared to a complete solid approach. The effectiveness of this approach is demonstrated through two numerical examples, including academic cantilever structures and an industrial multilayered composite structure.

在标准有限元程序中,用户自己选择在特定应用中使用哪种力学理论。为此,他要依靠从经验中获得的一些规则或一些理论考虑。但是,当几何形状、边界条件、载荷和材料非常复杂时,选择合适的理论可能是一项艰巨的任务。本文旨在定义一种适应性方法,在线性静态分析中,从理论选择的角度确定最佳有限元模型。本文定义了一个标准,用于在结构的每个部分选择相关的力学理论:实体、壳或梁。为整个结构定义实体网格,而在壳或梁区域分别采用特定的实体-壳或实体-梁方法。这就避免了从实体结构构建中表面或中轴几何结构的复杂工作,尤其是在工业应用中。在应用壳理论或梁理论的位移场时,节点之间存在运动学关系。这将产生一组线性方程,用于消除从属自由度。与完全实体方法相比,所提出的方法也可以解释为一种缩小模型尺寸的方法。通过两个数值示例,包括学术悬臂结构和工业多层复合结构,证明了这种方法的有效性。


Non-stationary response analysis for sandwich panels with corrugated cores under moving random loads

Bo Li, Dong Shao, Yongqiang Tao, Ningze Sun, Hong zhang

doi:10.1016/j.tws.2024.112131

带波纹芯材的夹芯板在移动随机载荷作用下的非稳态响应分析

In this work, a recursion reverberation-ray matrix method (RRRM) is presented to formulate an exact and unified solution for the non-stationary responses analysis of the sandwich panels with corrugated cores (SPCC) subjected to the moving random loads. The governing equations for the basic units are obtained by employing the simple first-order shear deformation theory (S-FSDT) and Hamilton's principle. Then, based on the traditional reverberation ray matrix method (MRRM), the RRRM is established by incorporating a bidirectional recursion technique to effectively calculate the exact solutions of the whole model. Thereinto, the kinematic relation matrix between the cell units can be constructed to facilitate the coupling of various desired numbers of elements by employing the virtual coupling spring. In addition, a unified loading mechanism for multi-scenario loads is proposed by integrating the pseudo-excitation method (PEM) with the load stage division technique. The applicability and accuracy of the current method to non-stationary response behaviors of the SPCC are clarified by carrying out sufficient comparative studies between the calculated results with reference solutions from FEM and Monte Carlo simulation method. Furthermore, several meaningful conclusions are drawn regarding the effects of structural and load parameters on the vibration characteristic, non-stationary displacement response, power spectrum density (PSD), and time-varying root mean square (RMS).

本研究提出了一种递归混响射线矩阵法(RRRM),为带波纹芯材的夹芯板(SPCC)在移动随机载荷作用下的非稳态响应分析提供了一种精确而统一的解决方案。利用简单一阶剪切变形理论(S-FSDT)和汉密尔顿原理获得了基本单元的控制方程。然后,在传统的混响射线矩阵法(MRRM)基础上,结合双向递归技术建立了 RRRM,从而有效地计算出整个模型的精确解。在此基础上,可以构建单元之间的运动关系矩阵,从而通过使用虚拟耦合弹簧,方便地耦合各种所需数量的元素。此外,通过将伪激振法(PEM)与载荷阶段划分技术相结合,提出了适用于多场景载荷的统一加载机制。通过将计算结果与有限元法和蒙特卡罗模拟法的参考解进行充分对比研究,阐明了当前方法对 SPCC 非稳态响应行为的适用性和准确性。此外,还就结构和载荷参数对振动特性、非稳态位移响应、功率谱密度(PSD)和时变均方根(RMS)的影响得出了一些有意义的结论。


Multiscale damage and low-velocity impact study of three-dimensional woven composites

Kunkun Jing, Hui Zhou, Hao Wang, Hongyu Yan, Suchao Xie

doi:10.1016/j.tws.2024.112132

三维编织复合材料的多尺度损伤和低速冲击研究

Three-dimensional woven composites address the limitation of weak interlaminar strength found in traditional laminated composites and offer superior resistance to out-of-plane impact. However, the complex material composition and structural intricacies necessitate investigation into their damage mechanisms. This study introduces novel and reliable microscale and mesoscale Representative Volume Element (RVE) models for three-dimensional woven composites, developed through advanced CT scanning and comprehensive multi-directional tensile and shear experiments. The research explores the impact of fiber volume fraction on yarn mechanical properties using the microscale RVE model, yielding precise macroscale homogenization parameters through the mesoscale RVE model. Furthermore, a macro-meso model tailored for low-velocity impact scenarios is established, significantly enhancing computational efficiency without compromising accuracy, thus providing support for further research on the impact properties of three-dimensional woven composites.

三维编织复合材料解决了传统层压复合材料层间强度较弱的局限性,并具有优异的抗平面外冲击能力。然而,由于材料成分复杂,结构错综复杂,有必要对其损伤机理进行研究。本研究通过先进的 CT 扫描和全面的多向拉伸和剪切实验,为三维编织复合材料引入了新颖可靠的微尺度和中尺度代表体积元素 (RVE) 模型。研究利用微观 RVE 模型探讨了纤维体积分数对纱线机械性能的影响,并通过中观 RVE 模型得出了精确的宏观均匀化参数。此外,还建立了针对低速冲击情景的宏观-中观模型,在不影响精度的前提下显著提高了计算效率,从而为进一步研究三维编织复合材料的冲击性能提供了支持。




来源:复合材料力学仿真Composites FEM
ACTMechanicalMarcDeform振动疲劳断裂复合材料ADS裂纹理论材料多尺度控制
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首次发布时间:2024-11-21
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【新文速递】2024年6月17日复合材料SCI期刊最新文章

今日更新:Composite Structures 1 篇,Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 1 篇Composite StructuresNovel interaction effects enhance specific energy absorption in foam-filled CFRP tapered tubesXinmei Xiang, Chenkun Xiao, Guoxing Lu, Yi Min Xie, Haiyang Yang, Jing Zhang, Ngoc San Hadoi:10.1016/j.compstruct.2024.118288新颖的相互作用效应增强了泡沫填充 CFRP 锥形管的比能量吸收能力This study unveils a novel interaction effect in the foam-filled CFRP tapered tubes that enhances their specific energy absorption (SEA), challenging the conventional understanding that foam fillers decrease the SEA of structures like foam-filled CFRP straight tubes and foam-filled metal tapered tubes. Quasi-static axial compression tests were conducted on foam-filled CFRP tubes with varying taper angles (0°, 5°, 10°, 15°) to confirm and quantify this newfound interaction effect. The energy absorption characteristics and interaction effect due to the foam filler in the foam-filled CFRP tapered tubes were thoroughly evaluated and compared to 3D-printed 316L stainless steel tubes and unfilled CFRP counterparts. Contrary to expectations, our results indicate that the foam-filled CFRP tubes consistently outperform both steel and unfilled CFRP tubes in energy absorption. Intriguingly, the CFRP foam-filled tapered tubes in this study demonstrated higher SEA compared to CFRP tubes without foam filler, underscoring the remarkable effectiveness of CFRP materials in foam-filled tapered tube applications. Our comprehensive interaction effect analysis highlights the substantial contribution of the unique synergy between the foam filler and the debris of the CFRP tapered tube to this increased SEA. Additionally, we propose a novel hybrid design that integrates straight and tapered CFRP tubes with foam fillers, leveraging the newfound interaction effect to further enhance the energy absorption of tapered tubes. This research not only emphasizes the advantages of foam fillers in enhancing CFRP tapered structures but also introduces innovative possibilities for energy absorption applications across various industries.本研究揭示了泡沫填充 CFRP 锥形管中的新型相互作用效应,这种效应可增强其比能量吸收(SEA),从而挑战了泡沫填充物会降低泡沫填充 CFRP 直管和泡沫填充金属锥形管等结构的 SEA 的传统认识。我们对不同锥角(0°、5°、10°、15°)的泡沫填充 CFRP 管进行了准静态轴向压缩试验,以确认和量化这种新发现的相互作用效应。对泡沫填充的 CFRP 锥形管的能量吸收特性和泡沫填充物的相互作用效应进行了全面评估,并与 3D 打印的 316L 不锈钢管和未填充的 CFRP 管进行了比较。与预期相反,我们的结果表明,填充泡沫的 CFRP 管在能量吸收方面始终优于钢管和未填充的 CFRP 管。耐人寻味的是,与未填充泡沫的 CFRP 管相比,本研究中填充泡沫的 CFRP 锥形管具有更高的 SEA 值,这表明 CFRP 材料在填充泡沫的锥形管应用中效果显著。我们进行了全面的相互作用效应分析,结果表明,泡沫填充物与 CFRP 锥形管碎片之间的独特协同作用对 SEA 的提高做出了重大贡献。此外,我们还提出了一种新型混合设计,将带有泡沫填料的直管和锥形 CFRP 管整合在一起,利用新发现的相互作用效应进一步提高锥形管的能量吸收能力。这项研究不仅强调了泡沫填料在增强 CFRP 锥形结构方面的优势,还为各行各业的能量吸收应用带来了创新的可能性。Composites Part A: Applied Science and ManufacturingAdvances in bulk TiB2-based composites: Densification and tougheningZhennan Cao, Jialin Sun, Keguo Zhang, Wenbin Ji, Kunlong Cai, Bin Li, Bo Liu, Chengqiang Fandoi:10.1016/j.compositesa.2024.108318块状 TiB2 基复合材料的进展:致密化和增韧TiB2 based materials have attracted extensive attention due to its considerable hardness and elastic modulus, excellent wear/ corrosion resistance as well as exceptional electrical/ thermal conductivity. The potential structural and functional applications of TiB2 based materials include reentry vehicles, cutting tools, thermal insulation boards, new energy batteries, ballistic protection high temperature nuclear reactors. However, the poor densification together with inferior fracture toughness dramatically limited the practical application of TiB2. Herein, we critically survey, summarize, and discuss the recent advances on preparation and mechanical properties of TiB2-based materials, focusing on the current understanding of densification and toughening strategies and mechanisms. Borrowing the concept of cemented carbide, cemented TiB2 is proposed in this review, highlighting the different binder phase on improving the densification of TiB2, including metal, intermetallic, ceramic and high entropy alloy. Subsequently, through discussing the factors influencing the efficiency of toughening TiB2, we determine and compare various toughening approaches on TiB2. Furthermore, the challenges and prospects of high performance TiB2 for future scientific researches and practical possibilities are also briefly summarized. We believe a thorough summary of the densification and toughening mechanisms will significantly contribute to the development of dense, strong and tough TiB2 materials in a much more efficient way, advancing them for further wide applications.由于 TiB2 具有相当高的硬度和弹性模量、出色的耐磨性/耐腐蚀性以及优异的导电性/导热性,它已引起了广泛的关注。基于 TiB2 的材料在结构和功能方面的潜在应用包括重返大气层飞行器、切削工具、隔热板、新能源电池、防弹高温核反应堆。然而,较差的致密性和较差的断裂韧性极大地限制了 TiB2 的实际应用。在此,我们对基于 TiB2 的材料的制备和机械性能的最新进展进行了批判性的调查、总结和讨论,重点是目前对致密化和增韧策略及机制的理解。借用硬质合金的概念,本综述提出了硬质合金 TiB2,强调了不同粘结相对改善 TiB2 变质的作用,包括金属、金属间、陶瓷和高熵合金。随后,通过讨论影响 TiB2 增韧效率的因素,我们确定并比较了 TiB2 的各种增韧方法。此外,我们还简要总结了高性能 TiB2 在未来科学研究和实用可能性方面所面临的挑战和前景。我们相信,对致密化和增韧机理的全面总结将极大地促进以更高效的方式开发致密、高强度和高韧性的 TiB2 材料,推动其进一步广泛应用。Composites Part B: EngineeringRational structure design of metal-based cathode for high-rate and long-cycling sodium nickel chloride batteriesGuowei Xiong, Xiangwei Wu, Zhaoyin Wendoi:10.1016/j.compositesb.2024.111636用于高倍率和长循环氯化钠镍电池的金属基正极的合理结构设计High-temperature sodium-nickel chloride (Na-NiCl2) batteries represented as an advanced energy storage technology show impressive advantages including abundant raw materials, high safety and long-cycling life. Nevertheless, their large-scale application is still hindered by the poor stability and rate capability of the cathode. In this work, we designed a three-dimensional cross-linked network composed of NiFe alloy nanowires via a magnetic-field assisted method. The as-prepared NiFe nanowires (NiFe NWs) are mixed with NaCl as the composite cathode of sodium-metal chloride batteries, delivering exceptionally enhanced rate performance (150.3 mAh/g@0.88 C) and superior cycling stability (84.3% capacity retention after 500 cycles). The properties are superior to those of the cathode based on the pristine Ni nanowires or the NiFe nanoparticles, which is ascribe to the existence of active Fe metal and the continuous conductive network, as confirmed by kinetics analysis. After experiencing a long-term cycling at large current density (∼0.88 C), no obvious coarsening of NiFe NWs and NaCl particles occurs. Moreover, the large-size Na-NiCl2 battery with capacity of 229 mAh reaches a practical energy density of 265.65 Wh kg−1 (∼0.3 C) with energy efficiency of 88.6%. Therefore, our work provides a guide for rational design of cathode structure, thereby improving rate and cycling performance of Na-NiCl2 batteries.高温氯化钠镍(Na-NiCl2)电池作为一种先进的储能技术,具有原料丰富、安全性高、循环寿命长等显著优势。然而,其大规模应用仍然受到阴极稳定性和速率能力差的阻碍。在这项研究中,我们通过磁场辅助方法设计了一种由镍铁合金纳米线组成的三维交联网络。制备的镍铁合金纳米线(NiFe NWs)与氯化钠(NaCl)混合后用作氯化钠金属电池的复合阴极,可显著提高速率性能(150.3 mAh/g@0.88 C)和循环稳定性(500 次循环后容量保持率为 84.3%)。其性能优于基于原始镍纳米线或镍铁纳米颗粒的阴极,这归功于活性铁金属的存在和连续的导电网络,这一点已通过动力学分析得到证实。在大电流密度(∼0.88 C)下长期循环后,镍铁纳米线和氯化钠颗粒没有发生明显的粗化现象。此外,容量为 229 mAh 的大尺寸 Na-NiCl2 电池的实用能量密度达到 265.65 Wh kg-1 (∼0.3 C),能量效率为 88.6%。因此,我们的工作为合理设计正极结构提供了指导,从而提高了 Na-NiCl2 电池的速率和循环性能。Composites Science and TechnologyExperimental and numerical evaluation of the influence of voids on sound absorption behaviors of 3D printed continuous flax fiber reinforced PLA compositesZhixiong Bi, Qian Li, Zhen Zhang, Zhongsen Zhang, Weidong Yang, Yan Lidoi:10.1016/j.compscitech.2024.110720 空隙对 3D 打印连续亚麻纤维增强聚乳酸复合材料吸声行为影响的实验和数值评估This study aims to quantitatively analyze the effects of voids on sound absorption properties of 3D printed continuous flax fiber reinforced PLA composites (CFFRCs). Three kinds of flax yarns with different linear density were employed to prepare CFFRCs via 3D printing technology. The sound absorption performances of these composites were measured using the impedance tube based on the two-microphone transfer function method. The microstructure morphologies including cross-sections of flax yarns, voids shape and distributions of the composites were observed via ultra-depth microscope and micro-computed tomography to reconstruct the exact structures in simulation. Mercury intrusion porosimetry was applied to measure the voids dimensions of CFFRCs. The influence of voids on sound absorption mechanisms of CFFRCs were revealed based on thermoviscous acoustics theory by conducting the simulation in COMSOL software. The experimental results demonstrated that CFFRCs exhibited excellent sound absorption coefficients (close to 1) within the frequency range of 150 to 350 Hz and 350 to 550 Hz, resulting from the voids inside and between the flax yarns respectively. With the increase of linear density (diameter of the yarn), the contents of voids inside and between the flax yarns both increased. The dimensions of voids inside the flax yarns improved while those between flax yarns remained unchanged. The existence of the voids between the flax yarns resulted in a decrease in the sound absorption coefficient of CFFRCs, while more voids inside flax yarns led to the increase of the sound absorption frequency. Numerical results indicated that voids between the flax yarns contributed to a more uniform change in sound speed, reducing sound absorption performance. Whereas, voids inside the flax yarns could improve viscous friction of soundwaves due to narrow structures, enhancing sound absorption capabilities. This study is anticipated to provide a guidance for the design of integration of structure and function of 3D printed CFFRCs.本研究旨在定量分析空隙对三维打印连续亚麻纤维增强聚乳酸复合材料(CFFRC)吸声性能的影响。研究采用三种不同线密度的亚麻纱线,通过三维打印技术制备 CFFRC。利用基于双传声器传递函数法的阻抗管测量了这些复合材料的吸声性能。通过超深显微镜和微型计算机断层扫描观察了复合材料的微观结构形态,包括亚麻纱的横截面、空隙形状和分布,从而在模拟中重建了确切的结构。汞侵入孔隙模拟法用于测量 CFFRC 的空隙尺寸。通过在 COMSOL 软件中进行模拟,基于热粘声学理论揭示了空隙对 CFFRC 吸声机制的影响。实验结果表明,CFFRC 在 150 至 350 Hz 和 350 至 550 Hz 频率范围内表现出优异的吸声系数(接近 1),这分别是由于亚麻纱内部和亚麻纱之间的空隙造成的。随着线性密度(纱线直径)的增加,亚麻纱线内部和纱线之间的空隙含量都有所增加。亚麻纱内部空隙的尺寸有所改善,而亚麻纱之间空隙的尺寸保持不变。亚麻纱之间空隙的存在导致 CFFRC 的吸声系数降低,而亚麻纱内部空隙的增加则导致吸声频率增加。数值结果表明,亚麻纱之间的空隙会使声速变化更加均匀,从而降低吸音性能。而亚麻纱线内部的空隙由于结构狭窄,可以改善声波的粘性摩擦,从而提高吸音能力。这项研究有望为三维打印 CFFRC 的结构与功能一体化设计提供指导。来源:复合材料力学仿真Composites FEM

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