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【新文速递】2024年2月10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 2 篇,Journal of the Mechanics and Physics of Solids 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 7 篇

International Journal of Solids and Structures

GLARE laminate subjected to multiple oblique low velocity impacts considering frictional tangential compliance

Sasanka Kakati, Debabrata Chakraborty

doi:10.1016/j.ijsolstr.2024.112701

考虑到摩擦切向顺应性,GLARE 层压板受到多次斜向低速冲击

The impacts occurring in real scenarios can be arbitrary, simultaneously impacting at different trajectories, giving rise to complexity in analysing the impact phenomena. This necessitates the implementation of a robust numerical finite element (FE) model capable of modelling such multiple impacts. The present paper investigates the multiple oblique low velocity impacts (OLVIs) on a clamped GLARE plate by spherical impactors exploring the influence of obliquity and their relative trajectories as well as the time delay between the OLVIs on the impact response and the extent of interfacial delamination. A 3D FE code has been developed considering the Hertzian contact model for modelling the normal component of contact and the theory of Mindlin and Deresiewicz is used for modelling tangential component considering friction. Results show that in addition to the obliquity of the impactors and the coefficient of friction, their relative trajectories, sizes and instant of their occurrences significantly influence the contact force histories, contact durations and the delamination at the interfaces.

真实场景中发生的撞击可能是任意的,同时以不同的轨迹发生撞击,从而导致撞击现象分析的复杂性。这就需要建立一个能够模拟这种多重撞击的稳健的数值有限元(FE)模型。本文研究了球形撞击器对夹紧的 GLARE 板的多次斜向低速撞击(OLVI),探讨了斜度及其相对轨迹以及 OLVI 之间的时间延迟对撞击响应和界面分层程度的影响。开发的三维 FE 代码采用赫兹接触模型模拟接触的法向分量,并采用 Mindlin 和 Deresiewicz 的理论模拟切向分量,同时考虑到摩擦力。结果表明,除了撞击器的倾斜度和摩擦系数外,它们的相对轨迹、大小和发生瞬间也会对接触力历史、接触持续时间和界面分层产生重大影响。


Experimental evaluation of elastic shear components for masonry in a Cosserat Continuum

Nandini Priya Thatikonda, Daniele Baraldi, Giosuè Boscato, Antonella Cecchi

doi:10.1016/j.ijsolstr.2024.112715

科塞拉特连续体中砌体弹性剪力构件的实验评估

The current research proposes an experimental methodology to evaluate masonry pure shear components, with a particular focus on the validation of the Cosserat or micropolar model by adopting small-scale specimens. The Cosserat continuum model’s ability to represent rich media or textures is well-defined in the literature and ideal for characterising anisotropic materials such as masonry. The experimental validation is proposed using specimens derived from the REV (Representative Elementary Volume) at the micro-scale. This is realized by introducing mortar head joints to the standard triplet specimen, where two periodic masonry textures, the running and the stack bond (limit cases defining perfect and no overlap), are defined. These specimens are tested in two configurations, first simulating shear along the bed joints and second along the head joints, illustrating orthotropic shear configurations of a Cosserat model.

当前的研究提出了一种评估砌体纯剪力构件的实验方法,尤其侧重于通过采用小尺寸试样来验证 Cosserat 或微极性模型。Cosserat 连续介质模型能够表现丰富的介质或纹理,这在文献中已有明确定义,非常适合表征砌体等各向异性材料。实验验证建议使用从 REV(代表性基本体积)中提取的微尺度试样。具体做法是在标准三重试样中引入砂浆头接缝,并在其中定义两种周期性砌体纹理--流淌粘结和堆叠粘结(定义完全重叠和无重叠的极限情况)。这些试样在两种配置下进行测试,第一种是模拟沿床身接缝的剪力,第二种是沿顶端接缝的剪力,说明了 Cosserat 模型的正交剪力配置。


Journal of the Mechanics and Physics of Solids

On the (lack of) representativeness of quasi-static variational fracture models for unstable crack propagation

A. Chao Correas, J. Reinoso, P. Cornetti, M. Corrado

doi:10.1016/j.jmps.2024.105573

关于不稳定裂纹扩展的准静态变分断裂模型(缺乏)代表性问题

The present work is devoted to prove that unstable crack propagation events do not comply with quasi-static hypotheses and thus should be modelled by dynamic approaches. Comprehensive supporting evidence is provided on the basis of three different analyses conducted on multi-ligament unstable fracture conditions, including a simplified Spring-Mass model, detailed quasi-static and dynamic Phase Field fracture models, and bespoke experiments with 3D printed specimens. The obtained results unequivocally show that neglecting the inertial effects can lead to unsafe predictions in the presence of energetic barriers for the development of fracture. Likewise, quasi-static Phase Field fracture models are proven to yield crack patterns that disagree with the experimental evidence because they overlook the progressive diffusion of the mechanical information within the continuum. Moreover, the inability of quasi-static approaches to follow unstable crack propagation is shown to weaken the crucial irreversibility condition of fracture. Overall, these experimentally backed insights should be gravely reckoned with, for they are not exclusive to Phase Field fracture models but common to (almost) any variational approach to fracture, inter alia Cohesive Zone Models or Continuum Damage Mechanics.

本研究致力于证明不稳定裂纹扩展事件不符合准静态假设,因此应采用动态方法建模。在对多韧带不稳定断裂条件进行的三种不同分析基础上,提供了全面的支持证据,包括简化的弹簧-质量模型、详细的准静态和动态相场断裂模型,以及使用 3D 打印试样进行的定制实验。获得的结果明确显示,在断裂发展存在能量障碍的情况下,忽略惯性效应会导致不安全的预测。同样,准静态相场断裂模型也被证明会产生与实验证据不符的裂纹模式,因为它们忽略了连续体内部机械信息的逐渐扩散。此外,准静态方法无法跟踪不稳定裂纹的扩展,这也削弱了断裂的关键不可逆条件。总之,这些以实验为依据的见解值得认真对待,因为它们并不是相场断裂模型所独有的,而是(几乎)所有断裂变异方法(尤其是内聚区模型或连续损伤力学)所共有的。


International Journal of Plasticity

Deformation-induced structural multiplicity of tilt boundaries facilitating the formation of two-dimensional interfacial superstructures

Xiande Ma, Hongbo Xie, Shanshan Li, Weitao Jia, Yuping Ren, Gaowu Qin

doi:10.1016/j.ijplas.2024.103910

变形诱导的倾斜边界结构多重性有助于形成二维界面超结构

Understanding the interfacial structures and the induced solute segregation behaviors at the atomic scale can facilitate the design of high-performance materials. However, the diversity and concealed nature of interfaces often make it challenging to reveal the interfacial microstructures and the accompanying solute segregation phenomena. Here, we report the discovery of 8 types of asymmetric tilt grain boundaries (GBs) with solute segregation in a deformed and annealed Mg-rare-earth binary model alloy, by means of Z-contrast high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) observations. Molecular dynamics (MD) simulations provide a visual depiction of the atomic-scale characteristics of the periodic extension and compression sites in these tilt GBs. The first-principles density functional theory (DFT) calculations unveil the energetics of the well-ordered segregation behavior of solutes at these interfaces. It is confirmed that the selective segregation of solutes at substitutional sites in the periodic misfit-dislocations separated tilt GBs leads to the formation of 8 types of unique two-dimensional interfacial superstructures. Additionally, the MD simulations have revealed that solute segregation plays a pivotal role in governing the shear strength of tilt GBs by influencing the nucleation of dislocations at interfaces. Our atomic-scale insights provide valuable guidance for understanding the formation of tilt GBs within the wrought alloys and their pivotal role in facilitating solute segregation, enabling the creation of specific two-dimensional superstructures at interfaces. Furthermore, these insights hold promise for advancing the design of high-performance alloys through the application of GB engineering.

了解原子尺度的界面结构和诱导的溶质分离行为有助于设计高性能材料。然而,由于界面的多样性和隐蔽性,揭示界面微结构和伴随的溶质偏析现象往往具有挑战性。在此,我们报告了通过 Z 对比高角度环形暗场扫描透射电子显微镜(HAADF-STEM)观测,在变形退火的镁稀土二元模型合金中发现了 8 种具有溶质偏析的不对称倾斜晶界(GBs)。分子动力学(MD)模拟直观地描述了这些倾斜 GB 中周期性延伸和压缩点的原子尺度特征。第一原理密度泛函理论(DFT)计算揭示了这些界面上溶质有序分离行为的能量学原理。研究证实,溶质在周期性错配位移分离倾斜 GB 中的取代位点上的选择性偏析导致形成了 8 种独特的二维界面超结构。此外,MD 模拟还揭示出,溶质隔离通过影响界面位错成核,在控制倾斜 GB 的剪切强度方面起着关键作用。我们的原子尺度洞察力为理解锻造合金中倾斜 GB 的形成及其在促进溶质偏析方面的关键作用提供了宝贵的指导,使我们能够在界面上创建特定的二维超结构。此外,这些见解有望通过应用 GB 工程来推动高性能合金的设计。


Thin-Walled Structures

Corotational isogeometric shear deformable geometrically exact spatial form beam element for general large deformation analysis of flexible thin-walled beam structures

Qinghua Han, Chao Wu, Mingjie Liu, Hao Wu

doi:10.1016/j.tws.2024.111684

用于柔性薄壁梁结构一般大变形分析的对等等几何剪切变形几何精确空间形式梁元素

In this paper, a new 3D generic order corotational geometrically exact beam element undergoing arbitrarily large deformations is presented. The novelty of the formulation lies in the use of the standard corotational framework, that is the decomposition into rigid body motion and pure deformation, to derive not only the objective, path-independent and singularity-free spatial exact strain measure but also the internal force and the consistent tangent stiffness matrix. The new formulation is derived by firstly conducting the consistent linearization of the weak formulation for the equilibrium equations of Reissner–Simo theory in the spatial form. By constructing a co-rotated frame that continuously rotates and translates with the element, the nodal strain-producing deformations can be extracted with the rigid-body translations and rotations removed from the element total motion. Subsequently, the corotational deformation variables are exploited to establish the distribution of deformation field within the beam element through B-spline basis functions, and derive the invariant and path independent exact strain measure in the spatial form by Lie derivative formalism. Through performing the variational operations of the compact transformation between corotational and global variables, the consistent tangent stiffness matrix are derived in closed form of the discrete variables for deformation field of any order. The proposed formulation is applicable to not only low-order two-node geometrically exact elements but also high-order multi-node straight or curved ones. The accuracy and robustness of the new formulation are demonstrated through the solutions of various benchmark problems.

本文提出了一种新的承受任意大变形的三维通用阶相关几何精确梁元素。该公式的新颖之处在于使用了标准刚体框架,即分解为刚体运动和纯变形,不仅可以推导出客观的、与路径无关的、无奇异性的空间精确应变度量,还可以推导出内力和一致的切线刚度矩阵。首先,对空间形式的赖斯纳-西莫理论平衡方程的弱公式进行一致线性化,从而推导出新的公式。通过构建一个与元素一起连续旋转和平移的共旋转框架,可以从元素总运动中去除刚体平移和旋转,从而提取出产生变形的节点应变。随后,利用相关变形变量,通过 B-样条基函数建立梁元素内部的变形场分布,并通过李导数形式主 义推导出空间形式的不变且与路径无关的精确应变度量。通过对相关变量和全局变量之间的紧凑变换进行变分运算,以离散变量的封闭形式推导出任意阶变形场的一致切线刚度矩阵。所提出的公式不仅适用于低阶两节点几何精确元素,也适用于高阶多节点直线或曲线元素。通过对各种基准问题的求解,证明了新公式的准确性和稳健性。


Free vibration of non-Lévy-type rectangular line-hinged plates: Analytical solutions in the symplectic framework

Yueqing Shi, Chao Zhou, Zhuofan Ni, Zixuan Wang, Chengbo Wang, Rui Li

doi:10.1016/j.tws.2024.111692

非列维型矩形线啮合板的自由振动:交映框架中的解析解

The free vibration behavior of non-Lévy-type line-hinged plates is common in engineering, but it is intractable to deal with such an issue by analytical methods for the difficulties in solving the fourth-order partial differential equations under hinge conditions. This paper aims to extend the symplectic methodology to the free vibration of non-Lévy-type line-hinged plates. The solution procedure involves dividing a line-hinged plate into subplates, processing boundary and hinge conditions, formulating the corresponding subproblems which can be solved with an analytical symplectic superposition method, determining the imposed mechanical quantities, and integrating the solutions of subproblems. Compared to previous studies on line-hinged plates, the present analytical free vibration solutions are obtained with no need for predetermination of solution forms. The comprehensive results under six non-Lévy-type boundaries are all well validated and utilized for a parametric study, providing guidance for the structural design of hinged plates.

非列维类型线铰接板的自由振动行为在工程中很常见,但由于铰接条件下的四阶偏微分方程求解困难,用分析方法处理这一问题很棘手。本文旨在将交映法扩展到非列维类型线铰板的自由振动。求解过程包括将线铰接板分成若干子板,处理边界条件和铰链条件,提出相应的子问题(可以用解析交映叠加法求解),确定施加的力学量,并对子问题的解进行积分。与之前对线铰接板的研究相比,本分析自由振动求解无需预先确定求解形式。六种非列维类型边界下的综合结果都得到了很好的验证,并可用于参数研究,为铰链板的结构设计提供指导。


Application of Fourier feature physics-information neural network in model of pipeline conveying fluid

Ting Zhang, Rui Yan, Siqian Zhang, Dingying Yang, Anhao Chen

doi:10.1016/j.tws.2024.111693

傅立叶特征物理信息神经网络在管道输送流体模型中的应用

In addressing the intricate dynamic responses of pipeline conveying fluid characterized by spatiotemporal multi-scales and multi-modal contributions, Fourier feature-embedded physics-information neural network (FF-PINN) is proposed. By introducing Fourier feature mapping to decompose the temporal and spatial scale information, FF-PINN precisely captures the relatively low-frequencies on the macroscopic time scale as well as the relatively high-frequencies on the microscopic scale of the pipeline's vibration. This approach significantly overcomes the spectral bias encountered by PINN when learning high-frequency information. To verify the effectiveness and accuracy of this method, the proposed FF-PINN is applied to solve the pipeline conveying fluid model with fixed support at both ends. The relative L2 error between the obtained results and the reference solution is 1.8×10−2, concurrently with a significant reduction in computational time. Additionally, an analysis of hyperparameter σ selection is conducted to evaluate its impact on the performance of FF-PINN, while establishing the correspondence between hyperparameter and eigenvector frequency. The results demonstrate that choosing appropriate hyperparameters empowers FF-PINN to better learn the vibration of specific frequencies, enabling the accurate modeling of pipeline vibrations’ dynamic response. It provides a potent solution for solving spatiotemporal multi-scale complexity problems involving the superposition of high-and low-frequencies.

针对管道输送流体具有时空多尺度和多模态贡献的复杂动态响应,提出了傅立叶特征嵌入物理信息神经网络(FF-PINN)。通过引入傅立叶特征映射来分解时空尺度信息,FF-PINN 可精确捕捉管道振动在宏观时间尺度上的相对低频和微观尺度上的相对高频。这种方法大大克服了 PINN 在学习高频信息时遇到的频谱偏差。为了验证这种方法的有效性和准确性,我们将所提出的 FF-PINN 应用于求解两端有固定支撑的管道输送流体模型。求解结果与参考解之间的相对 L2 误差为 1.8×10-2,同时计算时间显著减少。此外,还分析了超参数 σ 的选择,以评估其对 FF-PINN 性能的影响,同时建立了超参数与特征向量频率之间的对应关系。结果表明,选择适当的超参数能使 FF-PINN 更好地学习特定频率的振动,从而实现管道振动动态响应的精确建模。它为解决涉及高频和低频叠加的时空多尺度复杂性问题提供了有力的解决方案。


Development and Experimental study of a new dual tee-section buckling-restrained brace

Yue Yuan, Yong Zhao, Chun-Lin Wang, Bin Zeng

doi:10.1016/j.tws.2024.111694

新型双三通截面屈曲约束支撑的开发与实验研究

A new buckling-restrained brace with a dual-tee core (DTBRB) was proposed to reduce the out-of-plane buckling of the core, improve the fatigue property, and increase the bearing capacity of the brace. The restraining part included the assembled restraining plates, the fillers, and the assembled channel steels. The core consisted of two T-sections separated from each other and placed symmetrically. The outer part of the core was utterly constrained by the assembled restraining plates, while the inner edge part was only restrained by the assembled channel steel, and the web was unrestrained. All DTBRB specimens performed excellent hysteretic behavior, and no obvious degradation of stiffness and bearing capacity was observed before the failure. The flange and web of DTBRB had multi-wave buckling deformation. Compared with the buckling-restrained brace with the rectangular section core, setting the web on the rectangular steel plate to form a tee-section core was an available approach to decrease the out-of-plane buckling of the flange. The web with a small height-to-thickness ratio had no obvious out-of-plane buckling and could effectively restrain the out-of-plane deformation of the flange. The web with a large height-to-thickness ratio had plastic buckling deformation, causing torsional deformation of the flange. The design formula to prevent the out-of-plane buckling of the web was established. The design method of the dual-tee core of DTBRB was proposed based on the suggestion of the partially buckling-restrained brace with a steel plate core.

提出了一种新型双锥芯屈曲约束支撑(DTBRB),以减少锥芯的平面外屈曲,改善疲劳性能,提高支撑的承载能力。约束部分包括组装好的约束板、填料和组装好的槽钢。核心部分由两个相互分离并对称放置的 T 型截面组成。核心的外侧部分完全受组装好的约束板约束,而内侧边缘部分仅受组装好的槽钢约束,腹板不受任何约束。所有 DTBRB 试样均表现出良好的滞后行为,在破坏前未观察到明显的刚度和承载能力下降。DTBRB 的翼缘板和腹板发生了多波屈曲变形。与采用矩形截面芯材的屈曲约束支撑相比,将腹板设置在矩形钢板上形成三通截面芯材是减少翼缘平面外屈曲的一种可行方法。高厚比小的腹板没有明显的平面外屈曲,能有效抑制翼缘的平面外变形。高厚比大的腹板会产生塑性屈曲变形,导致翼缘产生扭转变形。建立了防止腹板平面外屈曲的设计公式。根据钢板芯部分屈曲约束支撑的建议,提出了 DTBRB 双锥芯的设计方法。


Thermal-structural analysis of a large space hoop-column antenna under unidirectional solar radiations

Lingyi Wang, Hao Zhu, Wei Xu, Nanyu Meng

doi:10.1016/j.tws.2024.111695

单向太阳辐射下大型空间箍柱天线的热结构分析

A thermal-structural coupling analysis model of the hoop-column antenna is established with considering of the mutual influence between the deformation and heat conduction of the cable net and thin-walled tube truss in the antenna. In this model, the circumferential temperature gradient of the thin-walled tube is considered by using the Fourier thermal element model, while only the axial heat conduction is considered in the cable thermal analysis model. The accuracy of the established thermal-structural coupling analysis models of the cable and tube beam are verified by two numerical tests. Modal analysis as well as the frequency sensitivity analysis with respective to several structure parameters are performed. The modal analysis results are also verified by finite element (FE) simulation using the commercial FE software ANSYS. Thermal-structural coupling performances of the hoop-column antenna with and without considering of the reflector shadow effect being considered are conducted and compared through the established model. Temperature fields and displacements of the hoop-column antenna under unidirectional solar heat flux shocks in different directions are also calculated and compared. On this basis, influences of some key structural parameters on temperature and deformation of the hoop-column antenna are also examined. The thermal-structural coupling dynamic model established in this work can contribute to the early design of the hoop-column antenna.

考虑到天线中缆索网和薄壁管桁架的变形和热传导之间的相互影响,建立了箍柱天线的热结构耦合分析模型。在该模型中,薄壁管的圆周温度梯度是通过傅立叶热元件模型来考虑的,而电缆热分析模型只考虑了轴向热传导。所建立的电缆和管梁热结构耦合分析模型的准确性通过两次数值试验得到了验证。对几个结构参数分别进行了模态分析和频率敏感性分析。模态分析结果还通过使用商业 FE 软件 ANSYS 进行的有限元(FE)模拟进行了验证。通过建立的模型,对考虑和不考虑反射器阴影效应的箍柱天线的热结构耦合性能进行了比较。还计算并比较了在不同方向的单向太阳热流冲击下箍柱天线的温度场和位移。在此基础上,还研究了一些关键结构参数对箍柱天线温度和变形的影响。本研究建立的热-结构耦合动态模型有助于箍柱天线的早期设计。


Research on the formation mechanism and mechanical properties of refill friction stir riveting (RFSR) joints of aluminium alloy AA7075-T6

Huan Zhao, Yunpeng Liu, Yunwu Ma, Xuecheng Ping, Dongzhe Zhang, Yongbing Li

doi:10.1016/j.tws.2024.111696

铝合金 AA7075-T6 填充式搅拌摩擦铆接 (RFSR) 接头的形成机理和机械性能研究

In this study, a novel refill friction stir riveting (RFSR) process was proposed to achieve hybrid solid-state bonding and mechanical interlocking of high-strength aluminium alloy AA7075-T6 sheets. The size of mechanical interlock is predefined by the depth of groove designed on the rivet shank, and realized through sheet material refilling. High-quality solid-state bonding is also generated at the sheet faying surface under the high pressure and strong friction stir from the rivet. The quality characteristics, microstructure, heat generation, microhardness distribution and mechanical properties were systematically investigated to uncover the joint formation mechanism and verify the effectiveness of the RFSR process. The results reveal that a mechanical interlock with 82% of the predefined value was successfully achieved by sheet material refilling into the groove on the rivet shank. An extra mechanical interlock, which was formed between the rivet shank and trapped bottom sheet, further enhanced the joint strength. Continuous solid-state bonding with a width of 0.39 mm was also generated between the two sheets. Strengthened by the multiple connection features, the peak lap-shear and cross-tension forces reached up to 9.09 ± 0.24 kN and 6.82 ± 0.11 kN respectively, and the corresponding failure modes were rivet shank fracture and pull-out of rivet shank from the bottom sheet.

本研究提出了一种新型填充摩擦搅拌铆接(RFSR)工艺,以实现高强度铝合金 AA7075-T6 板材的混合固态粘接和机械互锁。机械互锁的尺寸由铆钉柄上设计的凹槽深度预先确定,并通过板材回填实现。在铆钉的高压和强摩擦搅拌作用下,板材熔合表面也会产生高质量的固态粘合。为了揭示连接形成机制并验证 RFSR 工艺的有效性,我们对质量特性、微观结构、发热、显微硬度分布和机械性能进行了系统研究。结果表明,通过板材重新填入铆钉柄上的凹槽,成功实现了机械互锁,达到预定值的 82%。在铆钉柄和受困底板之间形成的额外机械互锁进一步增强了连接强度。两块板材之间还形成了宽度为 0.39 毫米的连续固态粘接。在多重连接功能的加固下,搭接剪切力和交叉张力的峰值分别达到了 9.09 ± 0.24 kN 和 6.82 ± 0.11 kN,相应的失效模式为铆钉柄断裂和铆钉柄从底板拉出。


Dynamic crushing behavior of a novel bi-directional gradient lattice structure under axial and oblique impact loadings

Lei Yue, Hu Liu, Zhengqiang Cheng, Qianhua Kan, Guozheng Kang

doi:10.1016/j.tws.2024.111697

新型双向梯度晶格结构在轴向和斜向冲击载荷下的动态破碎行为

To meet the crashworthiness requirement of lightweight structures under different impact directions, a series of novel bi-directional gradient lattice structures (BD-GLSs) are proposed to improve their oblique impact resistance performance. In this paper, four types of BD-GLSs with both symmetric and asymmetric gradient topology configurations are constructed by varying the side lengths of lattice unit cells in xy-plane, and their crushing behavior under axial and oblique impact loadings are numerically investigated. The dynamic crushing behaviors are highlighted by comparing with the traditional uniform and uni-directional gradient lattice structures, which is validated via experiment studies. It is demonstrated that the specific energy absorption of the BD-GLSs with symmetric gradient topology configuration can achieve an increment of 42.26% as compared to the uniform lattice structure. Moreover, the specific energy absorption of BD-GLSs with symmetric gradient topology configuration is 47.63% higher than that of the uni-directional gradient lattice structure under oblique impact, which suggests that the bi-directional gradient topology can provide better crashworthiness performance under the oblique impact conditions. The symmetrical gradient topology configuration has greater bearing capacity and better crashworthiness under both axial and oblique impact loadings by comparing with other gradient topology configurations. The proposed bi-directional gradient topology configuration provides an optimal design strategy for the crashworthiness design of lightweight structures, especially in the case of unknown impact load directions, which has a great competitive advantage in crashworthiness applications.

为满足轻质结构在不同冲击方向下的耐撞性要求,本文提出了一系列新型双向梯度晶格结构(BD-GLS),以改善其抗斜冲击性能。本文通过改变网格单元在 xy 平面上的边长,构建了四种具有对称和非对称梯度拓扑配置的 BD-GLS 结构,并对其在轴向和斜向冲击载荷下的挤压行为进行了数值研究。通过与传统的均匀和单向梯度晶格结构的比较,突出了其动态破碎行为,并通过实验研究进行了验证。结果表明,与均匀网格结构相比,对称梯度拓扑结构的 BD-GLS 比能量吸收率提高了 42.26%。此外,在斜撞击条件下,对称梯度拓扑结构 BD-GLS 的比能量吸收比单向梯度晶格结构高出 47.63%,这表明双向梯度拓扑结构在斜撞击条件下具有更好的耐撞性。与其他梯度拓扑结构相比,对称梯度拓扑结构在轴向和斜向冲击载荷下都具有更大的承载能力和更好的耐撞性。所提出的双向梯度拓扑结构配置为轻质结构的耐撞性设计提供了一种最佳设计策略,尤其是在冲击载荷方向未知的情况下,在耐撞性应用中具有很大的竞争优势。




来源:复合材料力学仿真Composites FEM
ACTMechanicalSystemFluxDeform振动疲劳断裂通用电子裂纹理论材料分子动力学多尺度
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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15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 2 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 4 篇Composite StructuresAdjustable mechanical performances of 4D-printed shape memory lattice structuresYu Dong, Kaijuan Chen, Hu Liu, Jian Li, Zhihong Liang, Qianhua Kandoi:10.1016/j.compstruct.2024.1179714D 打印形状记忆晶格结构的可调机械性能Lattice structures are widely used due to their inherent advantages. With the development of smart devices, there is a growing demand for programmable, adjustable, and reconfigurable performances. However, a significant limitation of traditional lattice structures is that their shape, function, and performance cannot be changed after fabrication. In order to address this issue, we conducted experimental and simulated investigations on the shape memory effect, adjustable mechanical performances, and their deformation mechanism using the shape memory programming method. Two bending-dominated lattice structures, namely four curved bars lattice structure (FCBL) and sinusoidal wave horseshoe lattice structure (SWHL), were taken as examples. Results show that the deformation modes of both structures are switched from a bending-dominated mode to a stretching-dominated one after programming while exhibiting distinct bending sections. FCBL displays a 'C' shape with one bending section, whereas SWHL exhibits an 'S' shape with two bending sections. These deformation modes significantly enhance the tensile moduli by 480.9% (FCBL) and 1546% (SWHL), and change their Poisson’s ratio from -0.29 to 0.25 (FCBL) and -0.31 to 0.43 (SWHL), respectively. 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This study proposes a novel strategy to improve the bioactivity of BC and presents the great potential of biomimetic ECM microenvironment BC-based scaffold for repairing large cranial bone defects.原始细菌纤维素(BC)固有的生物惰性和缺乏三维(3D)大孔结构极大地阻碍了其作为组织工程支架用于骨再生。为解决这一问题,我们开发了一种简单有效的策略,通过使用 Ca2+ 交联短切 BC 纳米纤维,制造出一种具有优异生物活性和大孔结构的 BC 基支架。由于纤维素水合作用增强,Ca2+交联的大孔BC支架(MPBC@Ca)具有更好的结构稳定性。重要的是,BC 纳米纤维表面的 Ca2+ 可作为活性成核位点,加速羟基磷灰石(HAp)的沉积,有利于构建仿生骨组织细胞外基质(ECM)微环境。具有仿生 ECM 微环境的 HAp 沉积 MPBC@Ca 支架(HAp-MPBC@Ca)具有良好的细胞相容性,并能增强体外干细胞的成骨分化。此外,体内试验结果表明,仿生 ECM 微环境 HAp-MPBC@Ca 支架具有良好的骨诱导性,可加速颅骨组织再生。该研究提出了一种提高 BC 生物活性的新策略,并展示了基于生物仿生 ECM 微环境 BC 支架修复大面积颅骨缺损的巨大潜力。Composites Science and TechnologyMathematical study of the mechanical properties of NOL rings with different winding process parametersZesheng Huang, Wei Shen, Lifeng Chen, Lvtao Zhudoi:10.1016/j.compscitech.2024.110502 不同缠绕工艺参数下 NOL 环机械性能的数学研究This study investigates the impact of different winding tension parameters (40 N, 45 N, and 50 N) on the quality of fiber-wrapped products using the Navy Ordnance Laboratory (NOL) composite rings. Design Expert software was utilized to analyze the response surface of fiber winding process parameters, including winding tension, winding speed, and curing temperature, which significantly influence the mechanical properties of the fiber. Mathematical models were developed to understand the combined effects of these process parameters on the mechanical properties of NOL rings. Furthermore, a satisfaction function was employed to synthesize the two mechanical response variables into a comprehensive index for parameter optimization. Experimental validation was conducted to verify the reliability of the proposed design scheme.本研究使用海军军械实验室(NOL)的复合环,研究了不同缠绕张力参数(40 N、45 N 和 50 N)对纤维缠绕产品质量的影响。利用 Design Expert 软件分析了纤维缠绕工艺参数的响应面,包括缠绕张力、缠绕速度和固化温度,这些参数对纤维的机械性能有显著影响。通过建立数学模型,了解了这些工艺参数对 NOL 环机械性能的综合影响。此外,还采用了满意度函数,将两个机械响应变量综合成一个综合指标,用于参数优化。通过实验验证了所提设计方案的可靠性。Waste cotton stalks enhancing the impact and crystallization performances of polylactic acid/polypropylene composite with PP-g-mah compatibilizerJin Shang, Abdukaiyum Abdurexit, Ruxangul Jamal, Tursun Abdiryim, Xiong Liu, Fangfei Liu, Zhiwei Li, Yanqiang Zhou, Jin Wei, Xinsheng Tangdoi:10.1016/j.compscitech.2024.110485 废棉秆与 PP-g-mah 相容剂可提高聚乳酸/聚丙烯复合材料的抗冲击和结晶性能Although polymers based on polylactic acid (PLA) are considered by researchers as prime candidates for replacing traditional plastics, they are confronted with challenges including high production costs, limited thermal stability, and inferior impact resistance. In this study, novel composites with exceptional impact resistance, robust thermal stability, and satisfactory crystalline properties were fabricated by using PLA and polypropylene (PP) as raw materials, PP-g-MAH was employed as a compatibilizer to enhance the compatibility between the individual components. by adjusting the quantity of discarded cotton stalk fibers (CSF). The optimal mass ratio of CSF was determined to be 20%, resulting in a composite that exhibited a moderate increase of 56.31% in impact strength and a remarkable improvement of 23.05% in Vicat softening temperature. While the crystallinity was enhanced and the crystallization temperature (Tc) value decreased, the storage modulus also increased. Furthermore, the observed increase in storage modulus within the temperature range of 80 °C–100 °C was attributed to the influence of polymer cold crystallization. The hydrophobicity of the composite was enhanced. Significantly, this strategy can be extended to the application of other plant fibers, improving the crystalline properties of semi-crystalline polymers such as PLA and exemplifying the true ‘valorization of waste' through the secondary utilization of discarded CSF.尽管以聚乳酸(PLA)为基础的聚合物被研究人员视为替代传统塑料的主要候选材料,但它们也面临着生产成本高、热稳定性有限和抗冲击性差等挑战。本研究以聚乳酸(PLA)和聚丙烯(PP)为原料,采用 PP-g-MAH 作为相容剂,通过调整废弃棉秆纤维(CSF)的用量,制备出具有优异抗冲击性、强大热稳定性和令人满意的结晶特性的新型复合材料。最终确定 CSF 的最佳质量比为 20%,使复合材料的冲击强度提高了 56.31%,维卡软化温度显著提高了 23.05%。在提高结晶度和降低结晶温度 (Tc) 值的同时,还提高了储存模量。此外,在 80 °C-100 °C 的温度范围内观察到的储存模量增加是由于聚合物冷结晶的影响。复合材料的疏水性得到了增强。值得注意的是,这一策略可扩展到其他植物纤维的应用,改善半结晶聚合物(如聚乳酸)的结晶特性,并通过对废弃 CSF 的二次利用体现真正的 "废物利用"。Flexible bandwidth-enhanced metamaterial absorbers with epoxy/graphene nanoplatelets-silver nanowire polymer composites as substratesM. Anjali, Raghunath Sahoo, Lincy Stephen, C.V. Krishnamurthy, V. Subramaniandoi:10.1016/j.compscitech.2024.110492 以环氧树脂/石墨烯纳米片-银纳米线聚合物复合材料为基材的柔性带宽增强超材料吸收器The realm of flexible devices has seen considerable advancement in recent technology due to their ability to bend and conform to particular shapes. Flexible metamaterial absorbers offer the advantage of combining the features of conventional metamaterials with the attributes of conformal systems, thereby opening new avenues in electromagnetic technology. This work involves the realization of flexible metamaterial absorbers with epoxy/graphene nanoplatelets-silver nanowire (GnP-AgNW) polymer composites as substrates; with a bandwidth enhancement achieved by incorporating losses in the substrate and combining resonances in the unit cell. A novel in-situ technique is employed to synthesize the nanohybrid GnP-AgNW (GA) with different weight percentages of AgNWs grown on GnP (GAx; x = 10, 15, 20 wt%). The dielectric measurements of the polymers showed that an increase in weight percentages of AgNWs in the composite enhanced the dielectric constant as well as losses of the polymer (εr՛: 7.7 to 8.8 and εr՛՛: 0.62 to 1.12). The numerical study on the designed flexible metamaterial absorbers with these substrates of thickness 1.4 mm showed a maximum absorptivity of 99% with a bandwidth (having absorption >90%) varying between 1.2 and 1.86 GHz. The experimental measurements on the fabricated metamaterial absorber were found to match the simulation results closely. The polymer composites demonstrated in this work are attractive candidates as substrates for metamaterial absorbers for conformal applications. This paper approaches the problem of bandwidth enhancement of metamaterial absorbers by material engineering along with the resonant structure optimization leading to a synergetic effect in the properties of absorber.柔性器件能够弯曲并符合特定形状,因此在最近的技术领域取得了长足的进步。柔性超材料吸波材料具有将传统超材料的特性与保形系统的属性相结合的优势,从而为电磁技术开辟了新的道路。这项研究以环氧树脂/石墨烯纳米片-银纳米线(GnP-AgNW)聚合物复合材料为基材,实现了柔性超材料吸波材料;通过在基材中加入损耗和在单元格中结合共振实现了带宽增强。我们采用了一种新颖的原位技术来合成纳米杂化 GnP-AgNW(GA),在 GnP 上生长不同重量百分比的 AgNW(GAx;x = 10、15、20 wt%)。聚合物的介电测量结果表明,复合材料中 AgNWs 重量百分比的增加提高了聚合物的介电常数和损耗(εr՛:7.7 至 8.8;εr՛՛:0.62 至 1.12)。对使用这些厚度为 1.4 毫米的基底设计的柔性超材料吸波材料进行的数值研究表明,其最大吸收率为 99%,带宽(吸收率大于 90%)在 1.2 至 1.86 千兆赫之间。对制作的超材料吸收器的实验测量结果与模拟结果非常吻合。这项工作中展示的聚合物复合材料是具有吸引力的超材料吸收器基材,可用于保形应用。本文通过材料工程和谐振结构优化来解决超材料吸收器的带宽增强问题,从而在吸收器的性能方面产生协同效应。Trans-scale analysis of 3D braided composites with voids based on micro-CT imaging and unsupervised machine learningXinyi Song, Jin Zhou, Di Zhang, Shenghao Zhang, Pei Li, Longteng Bai, Xiaohui Yang, Feiping Du, Xuefeng Chen, Zhongwei Guan, Wesley J. Cantwelldoi:10.1016/j.compscitech.2024.110494 基于显微 CT 成像和无监督机器学习的空隙三维编织复合材料跨尺度分析Voids are unavoidable during the manufacturing of 3D braided composites. This study proposes an unsupervised machine learning method combined with micro-computed tomography (micro-CT) scanning and a progressive damage analysis to analyze defects in these composites at a trans-scale level. The method enables the creation of real multiscale models and the determination of the porosity in both the intra-yarn (1.52 %) and inter-yarn (5.04 %) planes. Here, the unsupervised machine learning method is introduced in a trans-scale damage analysis to reduce calculation dimensions and to visualize the clustering data. A user-defined material subroutine (UMAT) is also developed to implement the trans-scale damage model. The experimental validation of the simulation results demonstrates the effective trans-scale damage analysis, showing the predominant pull-shear damage in the yarns, which is primarily located at the interfaces both between the yarns and between the yarns and the matrix. Finally, based on the scanned geometric data the degradation in modulus and strength of 3D braided composites with porosity is studied.在三维编织复合材料的制造过程中,空洞是不可避免的。本研究提出了一种无监督机器学习方法,结合微型计算机断层扫描(micro-CT)和渐进式损伤分析,在跨尺度水平上分析这些复合材料中的缺陷。该方法可创建真实的多尺度模型,并确定纱内(1.52%)和纱间(5.04%)平面的孔隙率。在此,我们在跨尺度损伤分析中引入了无监督机器学习方法,以减少计算维数并实现聚类数据的可视化。此外,还开发了用户自定义材料子程序(UMAT)来实现跨尺度损伤模型。模拟结果的实验验证证明了跨尺度损伤分析的有效性,显示了纱线中主要的拉剪损伤,这种损伤主要位于纱线之间以及纱线与基体之间的界面。最后,根据扫描的几何数据,研究了带有孔隙率的三维编织复合材料的模量和强度退化情况。来源:复合材料力学仿真Composites FEM

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