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【新文速递】2024年2月17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,International Journal of Plasticity 1 篇,Thin-Walled Structures 10 篇

International Journal of Solids and Structures

Interfacial crack-tip fields in beaded fiber composites

Min Xu, H. Daniel Wagner, Bingbing An

doi:10.1016/j.ijsolstr.2024.112718

珠状纤维复合材料中的界面裂纹尖端场

Beaded fiber composites represent ingenious design strategies capable of resolving the conflicts between strength and toughness in most engineering materials. Although intermittent beading holds great potential for improving mechanical properties, the underlying mechanisms responsible for strengthening and toughening of beaded fiber composites are largely unknown. In this study, we explore near-tip fields of an interface crack between the fiber and the polymeric bead, which is associated with fiber-bead debonding in the course of fiber pullout. The post-yield strain softening followed by strain hardening of polymer matrix, and friction between the bead and matrix are accounted for in the numerical analyses. It is found that pullout of fibers leads to development of multiple shear bands near the tip of the interface crack between the fiber and bead, and coalescence of shear bands gives rise to a zone of high plastic strain. Compared with the low level of friction between the bead and matrix, the bead-matrix interface with high friction coefficient can generate a larger zone of high plastic strain, increasing the propensity of interfacial debonding between the fiber and bead. Furthermore, we have revealed the role of thin coating of carbon nanotubes (CNT). Adding a CNT coating on the fiber enables the emergence of a small zone of high plastic strain near the interface crack tip and reduces the shear stress levels, thereby delaying bead debonding. Additionally, the introduction of CNT coating facilitates stress transfer from the bead to fiber, leading to high pullout force. The findings of this study provide important mechanistic insight into the design principles of beaded fiber composites.

珠状纤维复合材料是一种巧妙的设计策略,能够解决大多数工程材料中强度和韧性之间的矛盾。虽然间歇性串珠在改善机械性能方面具有巨大潜力,但串珠纤维复合材料的强化和增韧机理在很大程度上还不为人知。在本研究中,我们探讨了纤维与聚合珠之间界面裂纹的近端场,这种裂纹与纤维拉拔过程中纤维与珠的脱粘有关。数值分析中考虑了聚合物基体的屈服后应变软化和应变硬化,以及珠子和基体之间的摩擦。研究发现,纤维的拉拔会导致纤维和珠子之间的界面裂纹尖端附近出现多条剪切带,剪切带的凝聚会产生高塑性应变区。与微珠和基体之间的低摩擦相比,摩擦系数高的微珠-基体界面会产生更大的高塑性应变区,从而增加纤维和微珠之间的界面脱粘倾向。此外,我们还发现了碳纳米管(CNT)薄涂层的作用。在纤维上添加碳纳米管涂层可使界面裂纹尖端附近出现一小块高塑性应变区,并降低剪应力水平,从而延缓珠子脱落。此外,引入碳纳米管涂层还能促进应力从珠到纤维的传递,从而产生较高的拉拔力。这项研究的结果为珠状纤维复合材料的设计原理提供了重要的机理启示。


International Journal of Plasticity

Coupling effect of loading mode and temperature on the deformation behaviors of TWIP β Ti alloy: From superior tensile strength-ductility synergy to low Charpy impact toughness

Q. Wang, B. Sang, J.Q. Ren, C. Xin, Y.H. Zhang, Q. Gao, W.F. Liu, Z.L. Ning, J.T. Yu, X.F. Lu

doi:10.1016/j.ijplas.2024.103920

加载模式和温度对 TWIP β Ti 合金变形行为的耦合效应:从优异的拉伸强度-电导率协同作用到较低的夏比冲击韧性

The Ti-8.5Cr-1.5Sn β Ti alloy with twinning induced plasticity (TWIP) effect was selected for the quasi-static tensile and Charpy impact tests at 298 K and 77 K to determine whether the strengthening and toughening strategy by TWIP effect can be extended to the cryogenic temperature. As the impact deformation temperature decreased from 298 K to 77 K, the Charpy impact toughness decreased obviously, even though a superior strength-ductility synergy was obtained under quasi-static tensile deformation at 77 K. Because the inhibition of deformation twins (DTs) activity under Charpy impact deformation at 77 K, together with the premature cracking along the formed twin boundaries (TBs), the density and width of the activated {332} DTs were significantly reduced. Meanwhile, the secondary DTs and {5 8 11} DTs also were restrained due to the width of primary DTs was too narrow. The above influencing factors resulted in the size of plastic deformation region at crack tip at 77 K was obviously smaller than that at 298 K. The crack preferentially initiated and propagated along primary TBs, and finally a low Charpy impact absorbed energy was displayed at 77 K.

选择具有孪晶诱导塑性(TWIP)效应的 Ti-8.5Cr-1.5Sn β Ti 合金在 298 K 和 77 K 下进行准静态拉伸和夏比冲击试验,以确定 TWIP 效应的强化和增韧策略是否可以扩展到低温。随着冲击变形温度从 298 K 降到 77 K,夏比冲击韧性明显降低,尽管在 77 K 的准静态拉伸变形下获得了优异的强度-韧性协同作用。由于在 77 K 的夏比冲击变形下变形孪晶(DTs)的活性受到抑制,加上沿形成的孪晶边界(TBs)过早开裂,活化的 {332} DTs 的密度和宽度显著降低。DTs 的密度和宽度明显降低。同时,次生 DT 和{5 8 11} DT 也因孪晶边界(TB)的形成而受到约束。DT 也由于一级 DT 的宽度过窄而受到限制。上述影响因素导致 77 K 时裂纹尖端塑性变形区的尺寸明显小于 298 K 时的尺寸,裂纹优先沿着一级 DT 引发并扩展,最终在 77 K 时显示出较低的夏比冲击吸收能。


Thin-Walled Structures

A new double superposition-based shear deformation theory for static analysis of multilayered composite and sandwich doubly-curved shells

Dongyong Yao, M. Lezgy-Nazargah

doi:10.1016/j.tws.2024.111703

基于双重叠加的剪切变形新理论,用于多层复合材料和夹层双曲面壳体的静力分析

The accuracy of a laminated shell theory usually increases by increasing the number of unknown parameters involved in defining its kinematical relations. On the other hand, the computational cost of the analysis also increases by increasing the number of unknown parameters of a laminated shell theory. Therefore, developing accurate shell models with a low number of unknown parameters is a key issue. In this study, a novel shear deformation shell theory with only seven unknown parameters is proposed. The kinematical relations of the presented multilayered shell model are derived based on the double superposition concept. The z/R term (ratio of thickness co-ordinate to radii of curvature) is considered in formulation for capturing cross-sectional warping effects. Governing equations of shells under static loads have been solved by developing an eight-node shell element. Numerical comparisons show that the presented shell model is an efficient tool for static analysis of cross-ply, angle-ply, and soft-core sandwich shells with various deepness and length-to-thickness ratios.

层叠壳理论的精度通常会随着定义其运动学关系的未知参数数量的增加而提高。另一方面,分析的计算成本也会随着层叠壳理论未知参数数量的增加而增加。因此,开发具有较少未知参数的精确壳模型是一个关键问题。本研究提出了一种只有七个未知参数的新型剪切变形壳理论。所提出的多层壳模型的运动学关系是基于双重叠加概念推导出来的。在公式中考虑了 z/R 项(厚度坐标与曲率半径之比),以捕捉横截面翘曲效应。通过开发八节点壳体元素,解决了静载荷下壳体的控制方程。数值比较表明,所提出的壳体模型是对具有不同深度和长厚比的交叉层、角层和软芯夹层壳体进行静态分析的有效工具。


A multiscale strategy for exploring the mechanical behavior of 3D braided composite thin-walled cylinders

Yutong Liu, Yuliang Hou, Thaneshan Sapanathan, Renjie Nie, Liang Meng, Yingjie Xu

doi:10.1016/j.tws.2024.111705

探索三维编织复合薄壁圆柱体力学行为的多尺度策略

The mechanical behavior of 3D braided composite (3DBC) thin-walled cylinders is investigated using a multiscale modeling approach. A curved-surface equivalent block-stacking based (EBSB) cell, is developed using local homogenization, to facilitate the trans-scale information transfer. It enables to simplify the complex architectures of 3DBCs with the reservation of local braided characteristics. The macroscale models have been constructed by arranging the EBSB cells. Subsequently, axial compression tests have been experimentally and numerically carried out on 3DBC thin-walled cylinders. The prediction errors are less than 4%, revealing a good agreement with the experimental measurements. Besides, the macroscale modeling only takes 0.33 h (20 min), confirming the high accuracy and efficiency of the multiscale modeling approach. The experimental and numerical results indicate that matrix cracking is the dominant damage mode for the thin-walled cylinder under axial compression. Moreover, various numerical simulations are performed on four types of grid-stiffened thin-walled cylinders, to analyze the enhancement effect of the stiffening-grid designs. In the axial compression loading case, the square-grid-stiffened (SGS) pattern provides higher enhancement of load-carrying capacity, while the cylinder with the X-grid-stiffened (XGS) pattern performs better during internal pressure, torsional, as well as the combined loading conditions. The numerical results reveal that the damage is prone to initiates within the skin-stiffener transition region, while the skin cracking results in the final failure of the grid-stiffened cylinders.

本文采用多尺度建模方法研究了三维编织复合材料(3DBC)薄壁圆柱体的力学行为。利用局部均质化技术开发了基于曲面等效块堆积(EBSB)单元,以促进跨尺度信息传递。它通过保留局部编织特性,简化了三维BC 的复杂结构。通过排列 EBSB 单元,构建了宏观模型。随后,对 3DBC 薄壁圆柱体进行了轴向压缩试验和数值试验。预测误差小于 4%,显示出与实验测量结果的良好一致性。此外,宏观建模仅需 0.33 小时(20 分钟),证实了多尺度建模方法的高精度和高效率。实验和数值结果表明,基体开裂是薄壁圆柱体在轴向压缩下的主要破坏模式。此外,还对四种网格加劲薄壁圆柱体进行了各种数值模拟,以分析加劲网格设计的增强效果。在轴向压缩加载情况下,方格栅加固(SGS)模式可提高承载能力,而采用 X 格栅加固(XGS)模式的气缸在内压、扭转和组合加载条件下表现更佳。数值结果表明,损伤容易在表皮-加劲件过渡区域内发生,而表皮开裂导致网格加劲圆柱体最终失效。


Rate-dependent behaviour of additively manufactured topology optimised lattice structures

Sami E. Alkhatib, Shanqing Xu, Guoxing Lu, Ali Karrech, Timothy B. Sercombe

doi:10.1016/j.tws.2024.111710

叠加制造拓扑优化晶格结构的速率依赖行为

Lattice structures offer a wide range of tuneable qualities that cannot be achieved with bulk materials. While lattice structures offer a range of tuneable qualities, including isotropic properties achievable in bulk materials, the advent of additive manufacturing (AM) advances research in this domain. Although several studies have characterized the quasi-static mechanical properties of lattice structures, there is limited experimental data available on their rate-dependent behaviour. Additionally, most lattice structures are anisotropic, making them unsuitable for applications where loading directions are unknown. In this study, a topology-optimised unit cell with nearly perfect isotropic stiffness is investigated for its isotropic specific energy absorption under high strain rates. The dynamic response of the structure is evaluated using 3 different materials: CPTi, AlSi10Mg, and 316LSS, and both experimental and numerical methods are employed. The influence of topology and relative density on the mechanical properties of the structure are explored, and the specific energy absorption isotropy is determined by loading the lattices in various orientations numerically. This research fills the gap in knowledge regarding the rate-dependent behaviour of lattice structures and offers insight into the potential for isotropic lattice structures in engineering applications.

晶格结构具有多种可调特性,而这些特性是块状材料无法实现的。虽然晶格结构提供了一系列可调整的特性,包括各向同性的特性,这些特性在块体材料中是可以实现的,但增材制造(AM)技术的出现推动了这一领域的研究。虽然已有多项研究对晶格结构的准静态机械特性进行了描述,但有关其速率依赖行为的实验数据却十分有限。此外,大多数晶格结构是各向异性的,因此不适合加载方向未知的应用。本研究对拓扑优化的单元格进行了研究,该单元格具有近乎完美的各向同性刚度,可在高应变速率下吸收各向同性的比能量。使用 3 种不同的材料对结构的动态响应进行了评估:采用实验和数值方法对 CPTi、AlSi10Mg 和 316LSS 这三种不同材料的结构进行了动态响应评估。研究探讨了拓扑结构和相对密度对结构机械性能的影响,并通过数值加载不同方向的晶格确定了比能量吸收的各向同性。这项研究填补了有关晶格结构随速率变化行为的知识空白,并为各向同性晶格结构在工程应用中的潜力提供了启示。


Effect of fiber layout on low-velocity impact response of intralaminar hybrid carbon/glass fiber braided composite pipes under internal pressure.

Lin Shi, Hua Yang, Zhenyu Wu, Laihu Peng, Qingqing Ni, Qinchuan Li

doi:10.1016/j.tws.2024.111711

纤维布局对内压下层内混合碳/玻璃纤维编织复合管道低速冲击响应的影响

This study investigated the low-velocity impact behaviors of intralaminar hybrid carbon/glass braided composite pipes under internal pressure. The effects of intralaminar fiber layout and internal pressure on the mechanical responses, damage extension, and material cost-effectiveness were analyzed. The internal damage distribution of composite pipes with different hybrid fiber alternating numbers but identical mix ratios was evaluated through Micro-CT three-dimensional damage reconstructions. The yarn splitting of brittle carbon fiber materials was mutually prevented by the induction of intra-yarn debonding and delamination damages by hybridization with ductile glass fiber materials, which were prone to produce out-of-plane displacement and shear stresses under impact loading. A smaller hybrid fiber alternating unit was conducive to exploiting the hybrid impact toughening effect by avoiding pure reinforced fiber materials aggregated under the impactor. Internal pressure had a supporting effect on the composite pipe and was effectively synergistic with the hybridization effect. The change in the dominant damage mode resulted in significant reductions in impact deformation and damage severity compared to the unpressurized case.

本研究探讨了层内混合碳/玻璃编织复合材料管道在内压作用下的低速冲击行为。分析了层内纤维布局和内压对力学响应、损伤扩展和材料成本效益的影响。通过 Micro-CT 三维损伤重建评估了不同混合纤维交替数量但混合比相同的复合管道的内部损伤分布。脆性碳纤维材料的纱线开裂与韧性玻璃纤维材料的纱线内脱胶和分层损伤相互防止,而韧性玻璃纤维材料在冲击载荷下容易产生平面外位移和剪切应力。较小的混合纤维交替单元有利于利用混合冲击增韧效应,避免纯增强纤维材料在冲击器下聚集。内部压力对复合管具有支撑作用,并与混合效应有效协同。与未加压情况相比,主要破坏模式的改变导致冲击变形和破坏严重程度显著降低。


Global dynamic characteristics analysis of GTF star gear transmission system considering ring gear elastic deformation

Haoran Zou, Sanmin Wang, Peng Chen, Jinshuai Ge, Linlin Liu

doi:10.1016/j.tws.2024.111712

考虑环形齿轮弹性变形的 GTF 星形齿轮传动系统的全局动态特性分析

For the purpose of weight reduction and load sharing, the ring gear in the geared turbofan engine(GTF) gearbox is relatively thin, which will cause significant deformation of the ring gear during operation, so that the influence of the elastic deformation of ring gear on the system's dynamic characteristics cannot be ignored. The cross-section structure of the ring gear in actual gearbox is relatively complex, which is not conducive to solve the ring gear elastic deformation. Therefore, the original ring gear with complex cross-section is simplified as a T-shaped section ring in this paper. And using material mechanics and elastic theory to derive the elastic deforming equation of the T-shaped section ring. In the derivation of the dynamic equation of the system, the elastic deforming equation of the equivalent ring gear is cleverly embedded in the dynamic equation, and an improved dynamic model of GTF star gear transmission system(GTF-SGT) with ring gear elastic deformation is formed. Then, the computation results of the improved dynamic model with ring gear elastic deformation, the dynamic model without ring gear elastic deformation and experimental results in existing literature are compared to check the necessity of considering ring gear elastic deformation and the accuracy of the improved dynamic model. Finally, the two-parameter plane of the ring thickness(h)-rim thickness ratio(λ) and the ring thickness(h)-width thickness ratio(ξ) is constructed, and the distribution map of GTF-SGT dynamic characteristic in parameter plane is obtained. From the global perspective, to study how the matching law between different structural size parameters of equivalent ring gear affects the dynamic characteristics of GTF-SGT. This is important for selecting the ring gear structural size.

出于减重和分担载荷的目的,齿轮传动涡扇发动机(GTF)变速箱中的环形齿轮相对较薄,在运行过程中会引起环形齿轮的显著变形,因此环形齿轮的弹性变形对系统动态特性的影响不容忽视。实际变速箱中的环形齿轮截面结构相对复杂,不利于解决环形齿轮的弹性变形问题。因此,本文将原来具有复杂截面的环形齿轮简化为 T 形截面环。并利用材料力学和弹性理论推导出 T 形截面齿圈的弹性变形方程。在推导系统动态方程时,巧妙地将等效环形齿轮的弹性变形方程嵌入动态方程中,形成了带环形齿轮弹性变形的 GTF 星齿轮传动系统(GTF-SGT)改进动态模型。然后,将带环形齿轮弹性变形的改进动力学模型、不带环形齿轮弹性变形的动力学模型的计算结果与现有文献中的实验结果进行比较,以检验考虑环形齿轮弹性变形的必要性和改进动力学模型的准确性。最后,构建了齿圈厚度(h)-齿圈厚度比(λ)和齿圈厚度(h)-齿宽厚度比(ξ)的双参数平面,得到了 GTF-SGT 动力特性在参数平面上的分布图。从全局角度研究等效环形齿轮不同结构尺寸参数之间的匹配规律对 GTF-SGT 动态特性的影响。这对于选择环形齿轮结构尺寸具有重要意义。


Nonlinear wave propagation in graphene incorporating second strain gradient theory

Bo Yang, Nicholas Fantuzzi, Michele Bacciocchi, Francesco Fabbrocino, Mahmoud Mousavi

doi:10.1016/j.tws.2024.111713

包含第二应变梯度理论的石墨烯非线性波传播

The exploration of graphene has attracted extensive interest owing to its significant structural and mechanical properties. In this research, we numerically investigate wave propagation in defect-free single-layer graphene, considering its geometrically nonlinear behavior through second-strain gradient elasticity. To capture the geometric nonlinearity, firstly, the nonlinear strain–displacement relations are introduced. The governing equation and associated boundary conditions are derived using Hamilton’s principle. Then, the weak form, including the element matrices, is established. The eigenvalue problem is solved for 2D wave propagation through periodic structures theory. Finally, the dynamical properties such as band structures, mode shapes, energy flow, and wave beaming effects are analyzed. The numerical results reveal that the geometric nonlinearity through the second strain gradient influences the wave propagation characteristics in graphene. The findings are significant and contribute to the understanding of graphene’s dynamic response, with implications for the engineering applications of graphene-based nanostructures.

由于石墨烯具有显著的结构和机械特性,对它的探索引起了广泛的兴趣。在本研究中,我们通过二次应变梯度弹性对无缺陷单层石墨烯中的波传播进行了数值研究,并考虑了其几何非线性行为。为了捕捉几何非线性,首先引入了非线性应变-位移关系。利用汉密尔顿原理推导出支配方程和相关边界条件。然后,建立包括元素矩阵在内的弱形式。通过周期结构理论求解了二维波传播的特征值问题。最后,分析了带状结构、模态形状、能量流和波束效应等动力学特性。数值结果表明,几何非线性通过第二应变梯度影响石墨烯的波传播特性。这些发现意义重大,有助于理解石墨烯的动态响应,对石墨烯基纳米结构的工程应用具有重要意义。


Low-frequency bandgap and vibration mitigation performance of metamaterial-tailored concrete-filled steel tube columns

F.M. Ren, J.R. Xiong, S.F. Li, S.Y. Tian, Y.S. Li, C.L. Lai, J.X. Mo

doi:10.1016/j.tws.2024.111714

超材料定制混凝土填充钢管柱的低频带隙和减振性能

Low-frequency vibrations, such as earthquakes and wind loads, may negatively affect the proper operation of buildings and bridges and even lead to structural failure. Even though, in the past two decades, metamaterial-based structures have been utilized in structure vibration suppression, it is mainly used in the mitigation of high-frequency vibrations, It has been an open challenge to suppress low-frequency vibrations below 100 and ensure adequate bearing capacity in engineering structures. In this work, we present metamaterial composite column structures with built-in local resonators to achieve the low-frequency vibration mitigation effect. Compared to ordinary concrete-filled steel tube (CFST) columns, the metamaterial columns (meta-columns) can utilize the rubber shear modulus to create a low-frequency flexural bandgap in 30-50Hz. Dynamic stiffness is introduced in the Timoshenko beam and Bloch's theorem, the metamaterial analytical model is established, and the bandgap generation mechanism and vibration reduction effect are analyzed in conjunction with numerical simulations. Then, the bandgap effect and vibration attenuation law of the meta-columns are investigated by shaker tests at different acceleration amplitudes. Guided by theory and simulations, we have successfully fabricated several meta-composite columns with low-frequency bandgaps, which attenuate up to half of the vibrational energy near the bandgap center. The bandgap ranges derived from the theoretical and numerical models show a high degree of consistency with the experimental results, with deviations generally within 10%, all indicating that a bandgap exists near the resonator self-oscillation frequency. Additionally, the bandgap is significantly affected by the number of unit cells and resonators, especially the meta-column with fewer resonators fails to form a bandgap where the top response is smaller than the bottom response. As the number of resonators and metamaterial units increases, the meta-columns exhibit wider bandgap and stronger vibration reduction performance.

地震和风荷载等低频振动可能会对建筑物和桥梁的正常运行产生负面影响,甚至导致结构失效。尽管在过去二十年中,基于超材料的结构已被用于结构振动抑制,但它主要用于缓解高频振动,而如何抑制 100 以下的低频振动并确保工程结构具有足够的承载能力一直是一个公开的挑战。在这项工作中,我们提出了内置局部谐振器的超材料复合材料柱结构,以实现低频振动缓解效果。与普通混凝土填充钢管(CFST)柱相比,超材料柱(meta-columns)可利用橡胶剪切模量在 30-50Hz 范围内产生低频挠曲带隙。在季莫申科梁和布洛赫定理中引入了动态刚度,建立了超材料分析模型,并结合数值模拟分析了带隙产生机理和减振效果。然后,通过不同加速度振幅下的振动台试验研究了超材料柱的带隙效应和振动衰减规律。在理论和模拟的指导下,我们成功地制造出了几种具有低频带隙的元复合材料柱,它们在带隙中心附近最多可衰减一半的振动能量。理论和数值模型得出的带隙范围与实验结果高度一致,偏差一般在 10%以内,这表明带隙存在于谐振器自振频率附近。此外,带隙还受到单元单元和谐振器数量的显著影响,尤其是谐振器数量较少的元柱无法形成带隙,即顶部响应小于底部响应。随着谐振器和超材料单元数量的增加,元柱表现出更宽的带隙和更强的减振性能。


Mechanical properties of bionic lattice and its hybrid structures based on the microstructural design of pomelo peel

Zhixuan Sun, Yu Gong, Zheng Bian, Jianyu Zhang, Libin Zhao, Ning Hu

doi:10.1016/j.tws.2024.111715

基于柚子皮微结构设计的仿生晶格及其混合结构的力学性能

Bionic design has been widely used in real life, while providing ideas for innovative design of structures. In this work, a bionic lattice structure (Y-structure) with negative Poisson's ratio effect is obtained based on the principle of bionic design by taking design inspiration from the microstructure of pomelo peel. Meanwhile, in order to reduce the fabrication difficulty, the Y structure is combined with the BCC structure to obtain four overall lattice structures containing the Y structure. The required samples are prepared by additive manufacturing technique using PA2200 as the matrix material. Quasi-static compression tests are performed on the specimens at room temperature, and the mechanical properties and energy absorption capacity of the bionic lattice structure are examined under different compression directions, considering the anisotropy of the structure. Through the experimental results, it can be found that, compared with the traditional BCC structure, the four lattice structures containing the bionic lattice show obvious anisotropy, and exhibit good mechanical properties in different directions, while the energy absorption capacity is also generally improved. However, the change in the occupancy ratio of the BCC structure has a significant effect on the mechanical properties of the mixed lattice structure. The results obtained in this study can provide valuable references for further creative new developments of lattice structures based on bionic principles.

仿生设计在现实生活中得到了广泛应用,同时也为结构的创新设计提供了思路。本研究基于仿生设计原理,从柚子皮的微观结构中汲取设计灵感,得到了一种具有负泊松比效应的仿生晶格结构(Y 结构)。同时,为了降低 制造难度,将 Y 结构与 BCC 结构相结合,得到了包含 Y 结构的四种整体晶格结构。以 PA2200 为基体材料,通过增材制造技术制备出所需样品。在室温下对试样进行准静态压缩试验,考虑到结构的各向异性,考察了仿生晶格结构在不同压缩方向下的力学性能和能量吸收能力。通过实验结果可以发现,与传统的 BCC 结构相比,含有仿生晶格的四种晶格结构表现出明显的各向异性,在不同方向上均表现出良好的力学性能,能量吸收能力也普遍提高。然而,BCC 结构占有率的变化对混合晶格结构的力学性能有显著影响。本研究获得的结果可为进一步创造性地开发基于仿生原理的新晶格结构提供有价值的参考。


A graded acoustic metamaterial rod enabling ultra-broadband vibration attenuation and rainbow reflection

Jia Lou, Hui Fan, Aibing Zhang, Menghui Xu, Jianke Du

doi:10.1016/j.tws.2024.111716

可实现超宽带振动衰减和彩虹反射的梯度声超材料棒

Broadband vibration suppression poses a significant engineering challenge, and researchers have turned to acoustic metamaterials (AMs) as a promising solution. Traditional periodic AMs, though effective, often have narrow band gaps that limit their practicality. This study focuses on the design of a graded AM rod that achieves ultra-broadband vibration attenuation and rainbow reflection. The graded rod consists of various sections with seamlessly interconnected band gaps. The design is based on the dispersion analysis of an infinite uniform AM rod, complemented by the transmission calculation of a finite graded AM rod. The study emphasizes the importance of incorporating a specific number of identical unit cells in each section and introducing a small amount of damping in each resonator for effective ultra-broadband vibration suppression. The designed AM rod effectively blocks the propagation of longitudinal waves, regardless of their incident direction. Furthermore, the research demonstrates the orderly filtration of frequency components along the wave propagation path, showcasing the phenomenon of acoustic rainbow reflection. This phenomenon is illustrated through finite element simulations. This work not only addresses the pressing engineering challenge of broadband vibration attenuation but also paves the way for the separation, collection and energy harvesting of elastic waves.

宽带振动抑制是一项重大的工程挑战,研究人员已将声学超材料(AMs)作为一种有前途的解决方案。传统的周期性超材料虽然有效,但通常具有狭窄的带隙,限制了其实用性。本研究的重点是设计一种可实现超宽带振动衰减和彩虹反射的分级 AM 棒。分级调幅棒由带隙无缝连接的不同部分组成。设计基于无限均匀 AM 棒的色散分析,并辅以有限分级 AM 棒的传输计算。研究强调了在每个部分加入特定数量的相同单元和在每个谐振器中引入少量阻尼以有效抑制超宽带振动的重要性。无论纵波的入射方向如何,所设计的调幅杆都能有效阻挡纵波的传播。此外,研究还展示了沿波传播路径对频率成分的有序过滤,展示了声虹反射现象。这一现象通过有限元模拟进行了说明。这项工作不仅解决了宽带振动衰减这一紧迫的工程难题,还为弹性波的分离、收集和能量采集铺平了道路。


Nonlinear properties prediction and inverse design of a porous auxetic metamaterial based on neural networks

Hongru Yan, Hongjun Yu, Shuai Zhu, Zelong Wang, Yingbin Zhang, Licheng Guo

doi:10.1016/j.tws.2024.111717

基于神经网络的多孔辅助超材料非线性特性预测与反设计

Auxetic metamaterials are widely applied in energy-absorbing systems and soft robots due to their superior mechanical properties. The properties of auxetic metamaterials are determined by their architectures, which means it is feasible to obtain metamaterials with target performance through structural design. This paper proposes a framework with neural networks to generate a nearly real-time prediction of the auxeticity and stiffness simultaneously of porous materials. Trained neural networks accurately provide computationally inexpensive predictions on response histories. Based on the prediction database given by the neural network, the parametric analysis can be conducted to provide the mutual influence and trend relationship of auxeticity and stiffness of the porous metamaterial. In addition, inverse design can also be conducted for seeking optimal architecture in terms of the auxeticity and stiffness quickly and accurately. With the method, the target nonlinear properties can be accurately and rapidly designed for porous metamaterials. The relative error of neural network predictions is less than 1.5% compared with experimental results, and less than 8.0% compared with the numerical results given by the finite element method. The proposed framework can be extended to more structural materials to provide design guideline.

辅助超材料因其卓越的机械性能而被广泛应用于能量吸收系统和软机器人中。辅助超材料的性能由其结构决定,这意味着通过结构设计获得具有目标性能的超材料是可行的。本文提出了一种神经网络框架,可同时对多孔材料的辅助性和刚度进行近乎实时的预测。经过训练的神经网络可以准确地对响应历程进行计算成本低廉的预测。根据神经网络提供的预测数据库,可以进行参数分析,以提供多孔超材料的辅助eticity 和刚度的相互影响和趋势关系。此外,还可以进行逆向设计,快速准确地寻求辅助系数和刚度的最佳结构。利用该方法,可以准确、快速地设计多孔超材料的目标非线性特性。与实验结果相比,神经网络预测的相对误差小于 1.5%,与有限元法给出的数值结果相比,相对误差小于 8.0%。所提出的框架可以扩展到更多的结构材料,为设计提供指导。




来源:复合材料力学仿真Composites FEM
ACTMechanicalAdditiveSystemDeform振动复合材料非线性拓扑优化建筑增材ECAD声学裂纹理论材料传动机器人多尺度仿生
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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4日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 3 篇,Journal of the Mechanics and Physics of Solids 3 篇,Mechanics of Materials 1 篇,International Journal of Plasticity 3 篇,Thin-Walled Structures 9 篇International Journal of Solids and StructuresMPNN based graph networks as learnable physics engines for deformation and crack propagation in solid mechanicsXiao-Ping Zhou, Kai Fengdoi:10.1016/j.ijsolstr.2024.112695基于 MPNN 的图网络作为可学习的物理引擎,用于固体力学中的变形和裂纹扩展In this paper, the message passage neural networks (MPNN) based graph networks is proposed for learning and prediction of boundary loading problem in solid mechanics. As a learnable physics engine, the proposed model is designed to learn from historical data to understand the rules of the physical system behind the data, and then to make predictions. By learning the historical displacement field sampling data of 2D intact plate, the proposed model successfully realizes its continuous displacement field prediction. On this basis, the trained model also achieves a good prediction in a plate containing holes under the same loading condition but without training, which verifies the generalization ability of the proposed model. Finally, the crack propagation can be realized by learning the historical data of the plate with prefabricated cracks subjected to tension, which shows the excellent predict ability and exciting prospect of the proposed model.本文提出了基于消息通道神经网络(MPNN)的图网络,用于学习和预测固体力学中的边界载荷问题。作为一个可学习的物理引擎,所提出的模型旨在通过对历史数据的学习来理解数据背后物理系统的规律,进而进行预测。通过学习二维完整板块的历史位移场采样数据,所提出的模型成功实现了连续位移场预测。在此基础上,经过训练的模型还能在相同加载条件下对含有孔洞但未经过训练的板材进行很好的预测,验证了所提模型的泛化能力。最后,通过学习预制裂缝板在拉力作用下的历史数据,可以实现裂缝扩展,这表明所提模型具有出色的预测能力和令人振奋的前景。A deep difference collocation method and its application in elasticity problemsZ.M. Huang, L.X. Pengdoi:10.1016/j.ijsolstr.2024.112692深差分配位法及其在弹性问题中的应用Based on the coordinate transformation and difference scheme, a deep difference collocation method (DDCM) that solves the partial differential equations (PDEs) via a square domain is proposed in this paper. In most of deep learning-based methods such as physics-informed neural networks (PINNs), boundary losses and calculation of the items of PDEs in a physical domain using automatic differentiation will result in time-consuming training. DDCM utilizes a difference approximation approach to expedite the computation of neural network derivatives, enhancing training efficiency. It is adaptable to irregular physical domains via coordinate transformation and provides versatility in enforcing boundary conditions, enabling partial or total elimination of boundary losses. This research covers the analysis of 2D and 3D elastic problems along with the Kirchhoff plate bending problem. The validity of the introduced method is verified by comparing the obtained results to those from theoretical solutions, Finite Element Method (FEM), and Boundary Element Method (BEM). In comparison with PINN, the proposed methodology demonstrates a notably enhanced computational efficiency in solving PDEs, and exhibits commendable stability under a specified computational memory constraint.本文基于坐标变换和差分方案,提出了一种通过方域求解偏微分方程(PDEs)的深度差分定位方法(DDCM)。在大多数基于深度学习的方法(如物理信息神经网络(PINN))中,边界损失和使用自动微分计算物理域中的 PDE 项将导致耗时的训练。DDCM 采用差分逼近方法,加快了神经网络导数的计算,提高了训练效率。它可以通过坐标变换适应不规则的物理域,并在强制执行边界条件时提供多功能性,从而可以部分或全部消除边界损失。这项研究涵盖了二维和三维弹性问题以及基尔霍夫板弯曲问题的分析。通过将获得的结果与理论求解、有限元法(FEM)和边界元法(BEM)的结果进行比较,验证了所引入方法的有效性。与 PINN 相比,所提出的方法明显提高了求解 PDE 的计算效率,并在特定的计算内存限制下表现出了值得称道的稳定性。A strain-gradient elastic theory for special Cosserat rodsVipin Kumar Yadav, Prakhar Guptadoi:10.1016/j.ijsolstr.2024.112696特殊 Cosserat 棒的应变梯度弹性理论Micro-and nano-rods have been identified for various applications in actuators, sensors, and energy harvesters. This paper develops a general framework for micro-and nano-rods based on the one-dimensional strain-gradient theory for special Cosserat rods that considers large displacement and rotation of the cross section, chirality, and size effects. Initially, we obtain the linear momentum balance and angular momentum balance equations for rods utilizing the three-dimensional strain-gradient elasticity theory. Subsequently, we derive the constitutive relations for the strain-gradient elastic rods while considering material objectivity. We further identify the strain-gradient measures and their corresponding higher-order forces and higher-order moment terms. Using these constitutive relations, we show the applicability of our theory by deriving several closed-form solutions for geometrically nonlinear thin rods undergoing extension, shear, torsion, and bending deformation. Finally, we rigorously examine the effect of the length scale parameter on all these deformations of the strain-gradient elastic special Cosserat rod under classical and higher-order boundary conditions. Our analysis through these interesting examples can help in developing next-generation architected metamaterials using micro-and nano-rods.微型和纳米杆已被确定可用于致动器、传感器和能量收集器等多种应用领域。本文以特殊 Cosserat 棒的一维应变梯度理论为基础,考虑了横截面的大位移和旋转、手性和尺寸效应,为微型和纳米棒开发了一个通用框架。首先,我们利用三维应变梯度弹性理论获得了棒的线动量平衡和角动量平衡方程。随后,我们在考虑材料客观性的同时,推导出应变梯度弹性杆的构成关系。我们进一步确定了应变梯度量及其相应的高阶力和高阶力矩项。利用这些构成关系,我们推导出了几何非线性细杆在发生拉伸、剪切、扭转和弯曲变形时的几种闭式解,从而证明了我们理论的适用性。最后,我们严格研究了在经典和高阶边界条件下,长度尺度参数对应变梯度弹性特殊 Cosserat 杆件所有这些变形的影响。我们通过这些有趣的例子进行的分析有助于利用微纳米棒开发下一代架构超材料。Journal of the Mechanics and Physics of SolidsEffective surface forces and non-coherent interfaces within the reduced relaxed micromorphic modeling of finite-size mechanical metamaterialsLeonardo A. Perez Ramirez, Félix Erel-Demore, Gianluca Rizzi, Jendrik Voss, Angela Madeodoi:10.1016/j.jmps.2024.105558有限尺寸机械超材料简化松弛微形态建模中的有效表面力和非相干界面This paper introduces for the first time the concepts of non-coherent interfaces and microstructure-driven interface forces in the framework of micromorphic elasticity. It is shown that such concepts are of paramount importance when studying the response of finite-size mechanical metamaterials at the homogenized macro-scale. The need of introducing interface forces is elucidated through numerical examples comparing reduced relaxed micromorphic simulations to their full-microstructured counterparts. These results provide a milestone for the understanding of metamaterials’ modeling at the homogenized scale and for the use of micromorphic-type models to achieve an accurate upscaling towards larger-scale metamaterials’ structures.本文首次在微形态弹性框架中引入了非相干界面和微结构驱动界面力的概念。研究表明,这些概念对于研究均质化宏观尺度下有限尺寸机械超材料的响应至关重要。通过对比简化松弛微形态模拟和全微形态模拟的数值实例,阐明了引入界面力的必要性。这些结果为理解超材料在均质化尺度上的建模以及使用微形态模型准确地升级到更大尺度的超材料结构提供了一个里程碑。Design of origami structures with curved tiles between the creasesHuan Liu, Richard D. Jamesdoi:10.1016/j.jmps.2024.105559设计折痕间有弧形瓦片的折纸结构An efficient way to introduce elastic energy that can bias an origami structure toward desired shapes is to allow curved tiles between the creases. The bending of the tiles supplies the energy and the tiles themselves may have additional functionality. In this paper, we present a basic theorem and systematic design methods for quite general curved origami structures that can be folded from a flat sheet, and we present methods to accurately find the stored elastic energy. Here the tiles are allowed to undergo curved isometric mappings, and the associated creases necessarily undergo isometric mappings as curves. These assumptions are consistent with a variety of practical methods for crease design. The h3 scaling of the energy of thin sheets (h=thickness) spans a broad energy range. Different tiles in an origami design can have different values of h, and individual tiles can also have varying h. Following developments for piecewise rigid origami Fan Feng et al. (2020), we develop further the Lagrangian approach and the group orbit procedure in this context. We notice that some of the simplest designs that arise from the group orbit procedure for certain circle groups provide better matches to the buckling patterns observed in compressed cylinders and cones than known patterns.在折痕之间铺设弧形瓦片是引入弹性能量的有效方法,这种能量可以使折纸结构偏向所需的形状。瓦片的弯曲提供了能量,瓦片本身也可能具有额外的功能。在本文中,我们提出了一个基本定理和系统的设计方法,适用于可从平板折叠的一般曲面折纸结构,并介绍了精确计算所储存的弹性能量的方法。在这里,瓦片可以进行曲线等距映射,相关的折痕也必然进行曲线等距映射。这些假设与折痕设计的各种实用方法一致。褶皱在折痕之间铺设弧形瓦片是引入弹性能量的有效方法,这种能量可以使折纸结构偏向所需的形状。瓦片的弯曲提供了能量,瓦片本身也可能具有额外的功能。在本文中,我们提出了一个基本定理和系统的设计方法,适用于可从平板折叠的一般曲面折纸结构,并介绍了精确计算所储存的弹性能量的方法。在这里,瓦片可以进行曲线等距映射,相关的折痕也必然进行曲线等距映射。这些假设与各种折痕设计的实用方法一致。薄片能量的 h3 比例(h= 厚度)跨度很大。折纸设计中的不同薄片可以有不同的 h 值,单个薄片也可以有不同的 h 值。根据范锋等(2020)对片状刚性折纸的研究,我们在此背景下进一步发展了拉格朗日方法和群轨道程序。我们注意到,某些圆组的群轨道程序所产生的一些最简单的设计与在压缩圆柱和圆锥中观察到的屈曲模式比已知模式更匹配。Machine learning and sequential subdomain optimization for ultrafast inverse design of 4D-printed active composite structuresXiaohao Sun, Luxia Yu, Liang Yue, Kun Zhou, Frédéric Demoly, Ruike Renee Zhao, H. Jerry Qidoi:10.1016/j.jmps.2024.105561机器学习和顺序子域优化用于 4D 打印活性复合材料结构的超快逆向设计Shape transformations of active composites (ACs) depend on the spatial distribution and active response of constituent materials. Voxel-level complex material distributions offer a vast possibility for attainable shape changes of 4D-printed ACs, while also posing a significant challenge in efficiently designing material distributions to achieve target shape changes. Here, we present an integrated machine learning (ML) and sequential subdomain optimization (SSO) approach for ultrafast inverse designs of 4D-printed AC structures. By leveraging the inherent sequential dependency, a recurrent neural network ML model and SSO are seamlessly integrated. For multiple target shapes of various complexities, ML-SSO demonstrates superior performance in optimization accuracy and speed, delivering results within second(s). When integrated with computer vision, ML-SSO also enables an ultrafast, streamlined design-fabrication paradigm based on hand-drawn targets. Furthermore, ML-SSO empowered with a splicing strategy is capable of designing diverse lengthwise voxel configurations, thus showing exceptional adaptability to intricate target shapes with different lengths without compromising high speed and accuracy. As a comparison, for the benchmark three-period shape, the finite element and evolutionary algorithm (EA) method was estimated to need 219 days for the inverse design; the ML-EA achieved the design in 54min; the new ML-SSO with splicing strategy requires only 1.97s. By further leveraging appropriate symmetries, the highly efficient ML-SSO is employed to design active shape changes of 4D-printed lattice structures. The new ML-SSO approach thus provides a highly efficient tool for the design of various 4D-printed, shape-morphing AC structures.活性复合材料(AC)的形状变化取决于组成材料的空间分布和活性响应。体素级复杂材料分布为实现 4D 打印 AC 的形状变化提供了巨大的可能性,同时也为有效设计材料分布以实现目标形状变化带来了巨大挑战。在此,我们提出了一种集成机器学习(ML)和顺序子域优化(SSO)的方法,用于超快反向设计 4D 印刷交流电源结构。利用固有的顺序依赖性,循环神经网络 ML 模型和 SSO 实现了无缝集成。对于不同复杂程度的多种目标形状,ML-SSO 在优化精度和速度方面都表现出了卓越的性能,可在几秒内得出结果。与计算机视觉技术相结合后,ML-SSO 还能在手绘目标的基础上实现超快、简化的设计-制造范例。此外,采用拼接策略的 ML-SSO 还能设计出不同长度的体素配置,从而在不影响高速度和高精度的前提下,展现出对不同长度复杂目标形状的超强适应性。作为比较,对于基准的三周期形状,有限元和进化算法(EA)方法估计需要 219 天才能完成逆向设计;ML-EA 只需 54 分钟即可完成设计;而采用拼接策略的新型 ML-SSO 仅需 1.97 秒。通过进一步利用适当的对称性,高效的 ML-SSO 被用于设计 4D 印刷晶格结构的主动形状变化。因此,新的 ML-SSO 方法为设计各种 4D 印刷形状可变交流结构提供了高效工具。Mechanics of MaterialsOn strength and toughness of soft staggered compositesSuhib Abu-Qbeitah, Mahmood Jabareen, Konstantin Y. Volokhdoi:10.1016/j.mechmat.2024.104935 关于软交错复合材料的强度和韧性In the search of light yet strong and tough materials the nature produced soft composites with the staggered architecture. In such design, a soft protein matrix connects rigid mineral platelets similar to the cement connecting bricks in construction. In the present work, we examine strength and toughness (the total energy dissipated in fracture) of soft composites from the “first principles”. The latter means that we do not postulate material strength and toughness in advance — they become an outcome of numerical solutions of the initial boundary value problem. We formulate the boundary value problem on the basis of the material-sink approach enforcing the damage description in constitutive equations. In addition to the classical nature-made staggered architecture, we examine some alternative possible designs of platelets inside the soft matrix. Comparisons show that the classical staggered design is the best one (among considered). Nature wins at the moment.为了寻找轻质而坚固的材料,大自然制造出了具有交错结构的软复合材料。在这种设计中,柔软的蛋白质基质连接着坚硬的矿物小板,就像建筑中连接砖块的水泥一样。在本研究中,我们从 "第一原理 "出发,研究软复合材料的强度和韧性(断裂时耗散的总能量)。后者意味着我们并不预先假定材料的强度和韧性--它们是初始边界值问题数值求解的结果。我们在材料沉降方法的基础上制定边界值问题,并在构成方程中强制进行损伤描述。除了经典的自然交错结构外,我们还研究了软基质内血小板的一些其他可能设计。比较结果表明,经典的交错设计是最好的设计(在所考虑的设计中)。目前,自然胜出。International Journal of PlasticityShock Compression of Porous Copper Containing Helium: Molecular Dynamics Simulations and Theoretical ModelBao Wu, XinXin Wang, HaoNan Sui, Qiang Bao, AnMin He, HaiQuan Sun, Qiang Wu, Pei Wangdoi:10.1016/j.ijplas.2024.103899含氦多孔铜的冲击压缩:分子动力学模拟和理论模型Shock compression of porous copper containing helium is studied via non-equilibrium molecular dynamic simulations. The results show that the shock propagation exhibits an elastic-plastic double-shockwave structure at low shock velocity. The shock Hugoniot elastic limit increases with higher gas concentration, and decreases with larger porosity, while almost independent of the shock velocity. The back-and-forth propagation of elastic shockwave between plastic shockwave and free surface leads to the occurrence of the special structure of “surface cap”, which can protect the porous metal in the vicinity of the free surface from collapse. The plastic shock propagates faster with higher gas concentration and gradually catches up with the elastic shockwave as shock intensity increases. Compared with porous copper without gas, the presence of helium significantly inhibits the post-shock temperature rising and the shock melting behavior. A new theoretical model was proposed to quantify the shock Hugoniot of porous materials containing gas. The model's predictions align well with MD simulations across a wide pressure range up to 100 GPa with different gas concentrations and porosities.通过非平衡分子动力学模拟研究了含氦多孔铜的冲击压缩。结果表明,在低冲击速度下,冲击波的传播呈现出弹塑性双冲击波结构。冲击休格尼奥特弹性极限随气体浓度的增加而增加,随孔隙率的增大而减小,但几乎与冲击速度无关。弹性冲击波在塑性冲击波和自由表面之间的来回传播导致了 "表面帽 "这种特殊结构的出现,它可以保护自由表面附近的多孔金属免于坍塌。气体浓度越高,塑性冲击波传播速度越快,随着冲击强度的增加,塑性冲击波逐渐赶上弹性冲击波。与不含气体的多孔铜相比,氦的存在明显抑制了冲击后的温度上升和冲击熔化行为。研究人员提出了一个新的理论模型来量化含有气体的多孔材料的冲击休格尼奥。在高达 100 GPa 的宽压力范围内,该模型的预测结果与不同气体浓度和孔隙率的 MD 模拟结果非常吻合。Investigation of failure mechanisms in dual-phase steels through cohesive zone modeling and crystal plasticity frameworksIlbilge Umay Aydiner, Berkehan Tatli, Tuncay Yalçinkayadoi:10.1016/j.ijplas.2024.103898通过内聚区建模和晶体塑性框架研究双相钢的失效机理Dual-phase (DP) steels are characterized by their good formability and interesting material properties, which primarily originate from their unique composition, combining the ductile ferrite phase with the hard martensite phase. At the microscale, DP steels exhibit various fracture mechanisms that need to be investigated through proper plasticity and failure models. These mechanisms include interface decohesion between ferrite-martensite and ferrite-ferrite phases, as well as martensite cracking, depending on the steel’s microstructure. In this study, crystal plasticity and cohesive zone frameworks are employed together with a ductile failure model in 3D polycrystalline Representative Volume Element simulations to address the multiscale characteristics of the fracture mechanisms in DP steels. The analysis requires an extensive parameter identification procedure, which is presented in detail. The obtained results demonstrate the framework’s capability to effectively identify the primary failure mechanisms correlated with crucial microstructural features, including crystallographic orientation, morphology, volume fraction, and stress triaxiality. Findings indicate that an increase in the connectivity of the martensitic phase induces a shift from ferrite-ferrite decohesion to ferrite-martensite decohesion and martensite cracking. Similarly, as the volume fraction of martensite increases, decohesions become constrained, making martensite cracking the main failure mode. The numerical observations regarding triaxiality highlight that as stress triaxiality increases, the predominant failure mechanism is changed from martensite cracking and ferrite-martensite decohesion to ferrite-ferrite decohesion.双相钢(DP)具有良好的成型性和有趣的材料特性,这主要源于其独特的成分,即韧性铁素体相与硬质马氏体相的结合。在微观尺度上,DP 钢表现出多种断裂机制,需要通过适当的塑性和失效模型进行研究。这些机制包括铁素体-马氏体相和铁素体-铁素体相之间的界面脱粘,以及马氏体开裂,具体取决于钢的微观结构。在本研究中,晶体塑性和内聚区框架与三维多晶代表体积元素模拟中的韧性破坏模型结合使用,以解决 DP 钢中断裂机制的多尺度特性问题。分析需要大量的参数识别过程,本文对此进行了详细介绍。获得的结果表明,该框架能够有效识别与关键微结构特征相关的主要断裂机制,包括晶体取向、形态、体积分数和应力三轴性。研究结果表明,马氏体相连接性的增加会导致从铁素体-铁素体解粘转变为铁素体-马氏体解粘和马氏体开裂。同样,随着马氏体体积分数的增加,解粘变得受限,使马氏体开裂成为主要的失效模式。有关三轴度的数值观测结果突出表明,随着应力三轴度的增加,主要的失效机制从马氏体开裂和铁素体-马氏体解粘转变为铁素体-铁素体解粘。Plasticity Induced Anelasticity: The Atomistic OriginSanjay Manda, Saurabh Kumar, Namit N. Pai, Lokesh Soni, Ujjal Tewary, Pratyank Rastogi, Syed Asif, Ajay S. Panwar, Indradev Samajdardoi:10.1016/j.ijplas.2024.103901 塑性诱导的无弹性:原子论起源Plastic deformation is associated with developments in both dislocation density and residual strain. This study used multi-scale diffraction-based, X-ray as well as electron diffraction, measurements to quantify and relate them. Though both increased with progressive tensile deformation, an inverse orientation dependent relationship clearly emerged. In particular, higher elastically strained regions were accommodated by dislocation walls of lower residual strain. These experimental observations provided a combined perspective of elastic-plastic strain gradients in experimental plasticity. This study was then was then extended towards anelasticity, or internal friction, as induced by plastic deformation and elastic-plastic strains. Plastic deformation is known to enhance internal friction loss factor, tanδ, which then leads to the so-called dislocation enhanced Snoek (DES) peak. However, the atomistic origin of DES, role of elastic versus plastic strain, has never been established. Experimental nano dynamic mechanical analysis (nano-dma) measurements were used to bring out the plasticity induced DES of near-(001) grains. Experimental DES, however, scaled with both dislocation density and residual strain. This ambiguity necessitated use of numerical simulations to decouple respective contributions. Firstly, continuum finite element simulations indicated a stronger impact of residual stress, than the total stress, on the experimental DES. Further, atomistic modeling simulated (i) single-crystal nano-dma response and (ii) corresponding developments in residual stress as well as dislocation density. In particular, the DES emerged as an attribute of the non-uniform residual strain field(s) associated with dislocation(s). The corresponding change(s) in the anisotropies of local activation energy landscape, for interstitial diffusion of carbon, determined the enhanced Snoek response. Our experiments plus numerical modeling, thus brought out, and for the first time, a unique atomistic perspective towards anelasticity induced by plastic deformation.塑性变形与位错密度和残余应变的发展有关。本研究利用基于 X 射线和电子衍射的多尺度衍射测量来量化这两者并将其联系起来。虽然二者都会随着拉伸变形的进行而增加,但明显出现了与取向相关的反向关系。特别是,弹性应变较高的区域被残余应变较低的差排壁所容纳。这些实验观察提供了实验塑性中弹性-塑性应变梯度的综合视角。随后,这项研究被扩展到由塑性变形和弹塑性应变引起的无弹性或内摩擦。众所周知,塑性变形会增强内摩擦损耗因子 tanδ,进而导致所谓的位错增强斯诺克(DES)峰。然而,DES 的原子论起源、弹性应变与塑性应变的作用尚未确定。实验性纳米动态机械分析(nano-dma)测量被用来揭示近(001)晶粒的塑性诱导 DES。然而,实验 DES 随位错密度和残余应变而变化。由于这种模糊性,有必要使用数值模拟来分解各自的贡献。首先,连续有限元模拟表明,残余应力比总应力对实验 DES 的影响更大。此外,原子模型模拟了 (i) 单晶纳米-dma 响应和 (ii) 残余应力以及位错密度的相应发展。特别是,DES 是与位错相关的非均匀残余应变场的属性。碳间隙扩散时,局部活化能景观各向异性的相应变化决定了斯诺克反应的增强。因此,我们的实验加上数值建模,首次以独特的原子论视角揭示了塑性变形引起的无弹性。Thin-Walled StructuresProtection mechanism of liquid-filled welded square steel container with polyurea elastomer subjected to small-arms bulletChen Tao, Chong Ji, Jiangang Tu, Yuting Wang, Changxiao Zhao, Xin Wangdoi:10.1016/j.tws.2024.111668聚脲弹性体充液焊接方钢容器在小武器子弹下的保护机制The hydrodynamic ram (HRAM) caused by projectile impact would cause severe local damage to and overall deformation of a liquid-filled container. To prevent serious damage and rapid loss of an internal liquid in a thin-walled liquid-filled container upon high-velocity impact, a method involving spraying polyurea elastomer to enhance the impact protection performance of a container was proposed. A ballistic gun was used to launch small-arms bullet to impact a polyurea-coated liquid-filled square steel tube (PCST), and the macroscopic damage characteristics were obtained. The microscopic damage characteristics of polyurea were observed by scanning electron microscopy, the expansion process of cavity in water was photographed by high-speed photography, and the influence mechanism of polyurea layer on HRAM and container protection was further explained by numerical simulation. Results showed that the deflection deformation of the PCST initially increased and then decreased with increasing polyurea thickness. When the thickness of the polyurea was 4 mm, the maximum deflection deformation decreased to 76.3% of that in the bare container. Competition was observed between the restraint of the polyurea layer and the influence of projectile deceleration on the HRAM, and the protective effect was weakened when the polyurea layer was thin. The polyurea dominated the overall constraint of the structure, and the enhancement of the HRAM aggravated tearing damage at the weak corner-welded joint. When the protective effect was enhanced, the protective ability of the polyurea layer to enhance the liquid-filled container was manifested in two aspects. First, the “self-healing” of polyurea blocked the bullet hole on the steel plate and prevented internal liquid leakage. Second, the energy absorption and deceleration of polyurea weakened the water, thereby reducing damage to the container.弹丸冲击造成的流体动力冲撞(HRAM)会对充液容器造成严重的局部损坏和整体变形。为了防止薄壁充液容器在受到高速撞击时内部液体的严重破坏和快速流失,提出了一种喷涂聚脲弹性体以提高容器撞击防护性能的方法。使用弹道枪发射小型武器子弹撞击聚脲涂层充液方钢管(PCST),获得了宏观损伤特征。利用扫描电子显微镜观察了聚脲的微观损伤特征,通过高速摄影拍摄了空腔在水中的膨胀过程,并通过数值模拟进一步解释了聚脲层对 HRAM 和容器保护的影响机理。结果表明,随着聚脲厚度的增加,PCST 的挠曲变形先增大后减小。当聚脲厚度为 4 毫米时,最大挠曲变形下降到裸容器的 76.3%。聚脲层的约束和弹丸减速对 HRAM 的影响之间存在竞争,当聚脲层较薄时,保护作用减弱。聚脲在结构的整体约束中占主导地位,而 HRAM 的增强加剧了薄弱的角焊缝处的撕裂破坏。当保护效果增强时,聚脲层对充液容器的保护能力增强表现在两个方面。首先,聚脲的 "自我修复 "功能堵住了钢板上的弹孔,防止了内部液体泄漏。其次,聚脲的吸能和减速作用削弱了水的作用,从而减少了对容器的损坏。Buckling and Post-Buckling Behavior of Top Flange Coped I-Beams with Slender Web PanelsAbbas Ghadami, Akram Jawdhari, Ghazaleh PourMoosavidoi:10.1016/j.tws.2024.111640带细长腹板的顶部翼缘加坡工字钢的屈曲和屈曲后行为In this work, a comprehensive parametric study, based on a robust finite element analysis validated by existing experimental results, was conducted to investigate the effects of plate slenderness, cope details, i.e. depth (dc), length (Lc), and initial geometrical imperfection, on the elastic, inelastic, and post-buckling behavior of top flange coped I-beams with slender web panel (CBSW). The analysis results showed that the primary failure mode is elastic/inelastic shear local buckling, resulting in the formation of an inclined tension field band on the coped web from the cope corner during the post-buckling stage. The ultimate resistance and failure mode of CBSWs are generally affected by both cope details and imperfection magnitude. A small cope (dc/D≤0.2 and Lc/D≤0.2, where D is beam depth) has a negligible effect on the elastic buckling mode shape and elastic local buckling resistance of CBSWs. Moreover, the failure mode of CBSWs generally shifts from inelastic local buckling to elastic local buckling (ELB) when decreasing the imperfection magnitude or increasing the web slenderness, cope depth, and cope length. The current design equations were found to accurately predict the ELB resistance of CBSWs with a maximum difference within 13%, but grossly overestimate (some cases up to 117%) the ultimate strength of CBSWs with small cope areas. To address this, a new equation was developed and significant improvement in the accuracy of the design prediction was obtained, particularly for CBSWs with small copes.在这项工作中,我们基于稳健的有限元分析并通过现有的实验结果进行了验证,开展了一项全面的参数研究,以探讨板的细长度、锁口细节(即深度 (dc)、长度 (Lc))和初始几何缺陷对带细长腹板的上翼缘锁口工字钢 (CBSW) 的弹性、非弹性和后屈曲行为的影响。分析结果表明,主要的破坏模式是弹性/非弹性剪切局部屈曲,导致在后屈曲阶段从斜角开始在连接腹板上形成倾斜的拉力场带。CBSW 的极限阻力和失效模式通常受拱缘细节和缺陷大小的影响。小拱度(dc/D≤0.2 和 Lc/D≤0.2,其中 D 为梁深度)对 CBSW 的弹性屈曲模式形状和弹性局部屈曲阻力的影响可以忽略不计。此外,当减小不完善度或增加腹板细长度、腹板深度和腹板长度时,CBSW 的破坏模式一般会从非弹性局部屈曲转变为弹性局部屈曲(ELB)。研究发现,目前的设计公式能准确预测 CBSW 的 ELB 抗力,最大差异在 13% 以内,但却严重高估了(某些情况下高达 117%)小坡口面积 CBSW 的极限强度。为了解决这个问题,我们开发了一个新的方程,大大提高了设计预测的准确性,尤其是对小拱顶的 CBSW 而言。Laboratory tests, numerical simulations and design of austenitic stainless steel semi-oval hollow section columnsShuai Li, Ou Zhaodoi:10.1016/j.tws.2024.111648奥氏体不锈钢半椭圆空心截面柱的实验室测试、数值模拟和设计Semi-oval hollow section is an innovative cross-section profile and consists of one semi-circular flange, one flat flange and two flat webs. While the semi-circular flange (exposed to fluid or wind) offers a low level of hydrodynamic or aerodynamic drag, the flat elements facilitate connections with other members. The flexural buckling behaviour and resistances of austenitic stainless steel semi-oval hollow section columns are investigated in this paper. An experimental programme was firstly conducted on two austenitic stainless steel semi-oval hollow sections, with six column specimens of varying member lengths adopted for each cross-section, and included tensile coupon tests, initial geometric imperfection measurements and pin-ended column tests. Both ‘C’-shaped flexural buckling (with failure specimens bowing towards semi-circular flanges) and ‘reverse C’-shaped flexural buckling (with failure specimens bowing towards flat flanges) were observed upon testing. The experimental programme was accompanied by a numerical modelling programme, with finite element models developed to simulate the test results and then adopted to conduct parametric studies to generate further numerical data. On the basis of the test and numerical data, the relevant buckling curves for austenitic stainless steel circular hollow section columns, as provided in the European code, American specification and Australian/New Zealand standard, were evaluated for their applicability to austenitic stainless steel semi-oval hollow section columns. The evaluation results generally revealed that the codified buckling curves led to overall accurate and consistent flexural buckling resistance predictions when used for austenitic stainless steel semi-oval hollow section columns.半椭圆形空心截面是一种创新的截面型材,由一个半圆形凸缘、一个扁平凸缘和两个扁平腹板组成。半圆形凸缘(暴露在流体或风中)提供了较低的流体动力或空气阻力,而扁平元件则便于与其他构件连接。本文研究了奥氏体不锈钢半椭圆形空心截面柱的挠曲屈曲行为和阻力。首先对两个奥氏体不锈钢半椭圆形空心截面进行了实验,每个截面采用六个不同长度的柱试样,包括拉伸试样试验、初始几何缺陷测量和针端柱试验。试验中观察到了 "C "形弯曲屈曲(失效试样向半圆形凸缘弯曲)和 "反 C "形弯曲屈曲(失效试样向扁平凸缘弯曲)。在开展试验项目的同时,还进行了数值建模项目,开发了有限元模型来模拟试验结果,然后采用有限元模型进行参数研究,以生成进一步的数值数据。根据试验和数值数据,对欧洲规范、美国规范和澳大利亚/新西兰标准中规定的奥氏体不锈钢圆形空心截面柱的相关屈曲曲线进行了评估,以确定其是否适用于奥氏体不锈钢半椭圆形空心截面柱。评估结果普遍表明,在奥氏体不锈钢半椭圆形空心截面柱中使用编纂的屈曲曲线时,可获得总体准确且一致的抗弯曲屈曲性能预测。Seismic behavior of prefabricated thin-walled CFST double-column bridge piersChao Gu, Xuanding Wang, Xuhong Zhou, Xiang Li, Yue Liao, Nina Zhengdoi:10.1016/j.tws.2024.111654预制薄壁 CFST 双柱桥墩的抗震性能This paper investigates the seismic behavior of a prefabricated thin-walled concrete-filled steel tubular (CFST) pier system composed of circular thin-walled CFST double-column, I-shaped steel beam, and precast reinforced concrete (RC) cap beam. Hysteretic tests were conducted on two slender double-column pier systems: one with prefabricated connections (prefabricated pier system), and the other one with traditional embedded connections (traditional pier system). The test results indicated that, compared with the traditional pier system, the pier system with prefabricated connections demonstrating an 18% increase in lateral resistance and a 5% higher ductility coefficient, despite the weld of the steel beam cracked prematurely. Finite-element numerical models were established based on the OpenSees platform and validated by the cyclic loading tests. A comprehensive investigation involving a total of 12 cases, encompassing both CFST piers and RC piers, was conducted to evaluate their seismic performance and economic efficiency. The analysis results revealed that the proposed prefabricated pier system offers notable advantages in seismic performance for both tall and low piers.本文研究了由圆形薄壁 CFST 双柱、工字形钢梁和预制钢筋混凝土(RC)盖梁组成的预制薄壁混凝土填充钢管(CFST)桥墩系统的抗震行为。对两种细长双柱桥墩系统进行了静力试验:一种是预制连接(预制桥墩系统),另一种是传统预埋连接(传统桥墩系统)。试验结果表明,与传统桥墩系统相比,尽管钢梁焊缝过早开裂,但采用预制连接的桥墩系统的抗侧能力提高了 18%,延性系数提高了 5%。基于 OpenSees 平台建立了有限元数值模型,并通过循环加载试验进行了验证。对 CFST 墩柱和 RC 墩柱共 12 个案例进行了综合调查,以评估其抗震性能和经济效益。分析结果表明,无论是高墩还是低墩,拟议的预制墩系统在抗震性能方面都具有显著优势。Passive vibration control of subsonic thin plate via nonlinear capacitance and negative capacitance coupled piezoelectric shunt dampingChao Wang, Guo Yao, Mingyu Liudoi:10.1016/j.tws.2024.111656通过非线性电容和负电容耦合压电分流阻尼实现亚音速薄板的被动振动控制As part of the aircraft wing, the thin plate is always affected by external airflow and harmonic excitation to generate undesirable nonlinear vibration behaviors, which will produce fatigue and damage to the aircraft. Therefore, it is necessary to develop some schemes for vibration control of subsonic thin plates. This work proposes a nonlinear piezoelectric shunt damping for nonlinear vibration control of subsonic thin plates. The nonlinear motion equation of the electromechanical coupling system is established by the extended Hamilton principle. The subsonic aerodynamic model is introduced by linear potential flow theory. Three different piezoelectric control circuits made up of inductance, resistance, nonlinear capacitance, and negative capacitance are considered. The nonlinear dynamic equations are solved by the Matcont toolbox. The first four generalized coordinates before and after the piezoelectric vibration control of the system are discussed. It can be observed that piezoelectric control has significant vibration suppression effects. The vibration control effects of three different piezoelectric control circuits are compared under different external excitation amplitude and airflow velocities. This study provides a relatively perfect piezoelectric control scheme for the vibration control of thin plates in subsonic airflow.作为飞机机翼的一部分,薄板总是受到外部气流和谐波激励的影响,产生不良的非线性振动行为,从而产生疲劳并损坏飞机。因此,有必要开发一些亚音速薄板振动控制方案。本研究提出了一种用于亚音速薄板非线性振动控制的非线性压电分流阻尼。机电耦合系统的非线性运动方程由扩展汉密尔顿原理建立。亚音速空气动力学模型由线性势流理论引入。考虑了由电感、电阻、非线性电容和负电容组成的三种不同的压电控制电路。非线性动态方程由 Matcont 工具箱求解。讨论了系统压电振动控制前后的前四个广义坐标。可以看出,压电控制具有显著的振动抑制效果。比较了三种不同压电控制电路在不同外部激励振幅和气流速度下的振动控制效果。这项研究为亚音速气流中薄板的振动控制提供了一种相对完美的压电控制方案。Highly Stretchable, Sensitive and Healable Polyurethane-urea/Graphene Nanocomposite Sensor for Multifunctional ApplicationsYin Yu, Zhaoyang Xu, Lisheng Xu, Yikuan Li, Tianqing Liu, Qingshi Meng, Xiao Su, Hsu-Chiang Kuan, Jiabin Dai, Jun Madoi:10.1016/j.tws.2024.111660 用于多功能应用的高拉伸性、灵敏性和可愈合性聚氨酯尿素/石墨烯纳米复合材料传感器Flexible wearable electronic devices offer promising potential for monitoring physiological signals. However, creating a single sensor that integrates high tensile strength, sensitivity, self-healing capabilities, and a wide working range presents a significant and multifaceted challenge. This study reports a novel nanocomposite consisting of polyurethane-urea elastomer (PUU) and graphene nanoplatelets (E-GNPs) that are mechanochemically modified with diethyltoluene diamine ethacure 100. A low electrical percolation threshold was observed at 4.17 vol% E-GNPs. The sensor based on the PUU nanocomposite at 7 vol% of graphene has revealed a gauge factor up to 17.57 and a wide working range of 361.76% with high tensile strength of 19.73 MPa. It can withstand 20,000 cycles at 50% strain. The sensor exhibits negative temperature dependence at 20–100 °C, with a resolution of 0.01/°C at 36–40 °C. Treatments with solvents and heat enable a healing efficiency for sensitivity of up to 70.46%. The healable sensor enables real-time monitoring of temperature and strain signals, making it ideal for wearable devices in human health and sports monitoring.柔性可穿戴电子设备具有监测生理信号的巨大潜力。然而,创建一个集高拉伸强度、高灵敏度、自愈能力和宽工作范围于一体的传感器是一项重大而多方面的挑战。本研究报告介绍了一种新型纳米复合材料,它由聚氨酯尿素弹性体(PUU)和石墨烯纳米片(E-GNPs)组成,并用二乙基甲苯二胺乙醯化物 100 对其进行了机械化学修饰。在 4.17 Vol% 的 E-GNPs 中观察到了较低的电渗阈值。基于石墨烯含量为 7 Vol% 的 PUU 纳米复合材料的传感器的测量系数高达 17.57,工作范围宽达 361.76%,抗拉强度高达 19.73 MPa。在 50%应变下,它可以承受 20,000 次循环。该传感器在 20-100 °C时呈负温度依赖性,在 36-40 °C时分辨率为 0.01/°C。使用溶剂和热处理可使灵敏度的愈合效率高达 70.46%。这种可愈合传感器能够实时监测温度和应变信号,是人体健康和运动监测领域可穿戴设备的理想选择。Investigations on Low-Velocity Ballistic Impact behaviour of Kevlar / Epoxy Composites Reinforced with Chopped Wet Spun Fibers Intruded with NanofillersNitin Mathusoothanaperumal Sukanya, Suresh Kumar Sundaramdoi:10.1016/j.tws.2024.111665用纳米填料填充的切碎湿法纺丝纤维增强的 Kevlar / 环氧树脂复合材料的低速弹道冲击性能研究The low-velocity ballistic behaviour of chopped fiber-reinforced Kevlar Epoxy composites has been investigated. The chopped fibers of ‘Poly Vinyl Alcohol’ were fabricated using a wet spinning machine and intruded with functionalised Carbon Nanotubes and reduced Graphene Oxide (rGO) both individually and synergistically. The characterisation performed on the spun fibers indicated that the addition of fillers improved the properties owing to the increase in the surface interactions. The tensile strength was seen to increase with the addition of fillers and a maximum improvement of 214.74 % was observed for the fiber with both CNT and rGO filler addition. These fibers were chopped and incorporated into the composites prepared by the ‘hand layup’ process. Tensile and Inter Laminar Shear Strength tests conducted on the prepared composite samples revealed that the hybrid samples had the maximum values. The chopped fiber with both the filler addition had an improvement of 15.02 % in tensile strength, 17.45 % in modulus and 67% in Inter Laminar Shear Stress (ILSS). This combination had the highest resistance to the projectile's motion under low-velocity ballistic impact also. All the targets were able to ‘ricochet’ the projectile with large Depth of Penetration values. The lowest DoP, lowest strike face cracking and no delamination was observed for the optimum reinforced composite target. The presence of chopped fiber improves the toughness by crack bridging, load sharing and creating prestressing in the composite.研究了短切纤维增强凯夫拉环氧树脂复合材料的低速弹道性能。聚乙烯醇 "短切纤维是用湿法纺纱机制造的,并单独或协同添加了功能化碳纳米管和还原氧化石墨烯(rGO)。对纺出的纤维进行的特性分析表明,由于表面相互作用的增加,填充物的添加改善了纤维的特性。拉伸强度随着填料的添加而增加,添加了 CNT 和 rGO 填料的纤维的拉伸强度最大提高了 214.74%。这些纤维被切碎并加入到通过 "手糊 "工艺制备的复合材料中。对制备的复合材料样品进行的拉伸和层间剪切强度测试表明,混合样品的拉伸和层间剪切强度值最大。同时添加两种填料的切碎纤维的拉伸强度提高了 15.02%,模量提高了 17.45%,层间剪切应力提高了 67%。在低速弹道冲击下,这种组合对弹丸运动的阻力也最大。所有目标都能以较大的穿透深度值 "弹射 "弹丸。最佳增强复合材料靶材的穿透深度最低,打击面裂纹最少,且无分层现象。切碎纤维的存在通过裂缝桥接、负载分担和在复合材料中产生预应力来提高韧性。Experimental and numerical study on the protective mechanism of the full helmet subjected to blast loadingsYongqiang Li, Jun Lin, Sheng Liu, Hengyi Zhu, He Zhang, Hualin Fandoi:10.1016/j.tws.2024.111666爆炸荷载下全头盔保护机制的实验和数值研究The efficacy of full helmets in ballistic protection is well established. However, their effectiveness against blasts remains uncertain. The study combines free-field blast tests and numerical simulations to comprehensively investigate the protective mechanism of the full helmet under blast shock waves. Four blast tests are conducted on a hybrid III dummy head model with various helmet configurations. Simultaneously, finite element (FE) models are developed to explore full helmet protection. Five blast scenarios are simulated, including bare head, helmet-head, helmet-mandible guard-head, helmet-visor-head, and full helmet models. The experimental results indicate that wearing the full protective helmet can effectively mitigate overpressure at the eyes and forehead, and the sealing of the helmet significantly affects the attenuation of the peak overpressure. The simulation results reveal that the full helmet can dramatically attenuate the head overpressure in the frontal blast but cause localized overpressure amplification due to the underwash effect. Meanwhile, shock wave propagation heavily relies on the gap between the head and foam pads. The effect of blast loading directions and helmet-mandible guard gap on the head overpressure are investigated. The findings indicate that the mandible guard and visor can cause localized overpressure amplification. The overpressure on the eyes and forehead regions has a linear relationship with the gap between the helmet and mandible guard.全盔在防弹方面的功效已得到公认。然而,它们对爆炸的防护效果仍不确定。本研究结合自由场爆炸试验和数值模拟,全面研究了爆炸冲击波下全头盔的防护机制。在混合三代假人头部模型上进行了四次爆炸试验,头盔配置各不相同。同时,还开发了有限元(FE)模型,以探索全头盔的保护机制。模拟了五种爆炸场景,包括裸头、头盔-头、头盔-易碎护板-头、头盔-遮阳板-头和全头盔模型。实验结果表明,佩戴全防护头盔能有效缓解眼睛和前额处的过压,头盔的密封性对峰值过压的衰减有显著影响。模拟结果表明,在正面爆炸中,全防护头盔可显著减弱头部超压,但由于下冲效应会导致局部超压放大。同时,冲击波的传播在很大程度上依赖于头部和泡沫垫之间的间隙。研究了爆炸加载方向和头盔与下颚护板间隙对头部超压的影响。研究结果表明,下颚护板和面罩会导致局部过压放大。眼睛和前额区域的过压与头盔和下颚防护罩之间的间隙呈线性关系。Hierarchical design and coupling deformation of lattice structures with variable unit cells manufactured by laser powder bed fusionDongming Li, Bingzhi Chen, Deyu Yue, Tongyuan Sun, Xu Zhangdoi:10.1016/j.tws.2024.111667通过激光粉末床熔融技术制造的具有可变单元格的晶格结构的分层设计和耦合变形With the development of additive manufacturing technology, lattice structures with complex topological shapes can be manufactured. In order to combine the advantages of stretch dominance and bend dominance, a hierarchical lattice structure composed of variable unit cell is proposed. The hierarchical lattice structures are manufactured by laser powder bed fusion (LPBF). Five different cell arrangement combinations are designed based on face centered cubic (FCC) with octet truss structure (OTS) at the macro scale. The mechanical performance and deformation behavior of the hierarchical lattice was investigated systematically through compressive experiments and numerical simulations. The deformation modes were captured with a digital camera. Then, the crashworthiness design on the Row layered structure parametric analysis was performed to discuss the effect of geometrical parameters including component ratio and size ratio. The results indicated that the hierarchical structure exhibits a mixed deformation mode among those the Row layered structure has the best energy absorption characteristics. And the specific ratios of these geometrical parameters significantly enhance the energy absorption of hierarchical structure. Overall, this work not only provides a novel solution for designing hierarchical structures, but also highlights the advantages of additive manufacturing techniques for manufacturing complex structures.随着增材制造技术的发展,具有复杂拓扑形状的晶格结构可以被制造出来。为了结合拉伸优势和弯曲优势,本文提出了一种由可变单元格组成的分层晶格结构。分层晶格结构是通过激光粉末床熔融(LPBF)制造的。在宏观尺度上,基于面心立方(FCC)和八元桁架结构(OTS)设计了五种不同的单元排列组合。通过压缩实验和数值模拟,系统地研究了分层晶格的机械性能和变形行为。用数码相机捕捉了变形模式。然后,对行列式分层结构进行了耐撞性设计参数分析,讨论了几何参数(包括部件比和尺寸比)的影响。结果表明,分层结构表现出混合变形模式,其中,Row 分层结构具有最佳的能量吸收特性。而这些几何参数的特定比例能显著提高分层结构的能量吸收能力。总之,这项工作不仅为分层结构的设计提供了一种新的解决方案,而且凸显了增材制造技术在制造复杂结构方面的优势。来源:复合材料力学仿真Composites FEM

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