今日更新：International Journal of Solids and Structures 2 篇，Journal of the Mechanics and Physics of Solids 2 篇，Mechanics of Materials 1 篇，International Journal of Plasticity 2 篇，Thin-Walled Structures 7 篇International Journal of Solids and StructuresMetabarriers for mitigating traffic-induced surface waves: Mechanisms dependence on buried arrangementsYifei Xu, Haoran Lu, Zhigang Cao, Songye Zhudoi:10.1016/j.ijsolstr.2024.113120减轻交通引起的表面波的超屏障：依赖于埋藏安排的机制Locally resonant metamaterials provide exceptional wave manipulation capabilities in the low-frequency regime. This study introduces a buried metabarrier, which can simultaneously harness both resonant and geometric scattering, to attenuate surface Rayleigh waves at both low and high frequencies induced by traffic. In particular, how the buried arrangements of metabarriers influence their resonant- and geometric-scattering mechanisms is investigated by considering the metabarrier units buried vertically and horizontally in the ground. To this purpose, a numerical finite element model, which is verified through comparisons with existing studies, is developed to analyze the attenuation performance of the metabarrier. Using this model, we perform parametric studies to examine the effects of the material properties and dimensions of the metabarriers on their attenuation behavior. Due to the resonant scattering, low-frequency Rayleigh waves are mainly reflected by the vertical metabarriers; in contrast, they are predominantly converted into refracted bulk waves by the horizontal metabarriers. Additionally, the geometric scattering of horizontal metabarriers yields Bragg effects, which can reflect more high-frequency Rayleigh waves and induce a partial mode conversion to transverse bulk waves. Our systematic investigations will, to some extent, facilitate the future design of a well-performing metabarrier attenuating broadband Rayleigh waves.局部共振超材料在低频区域提供了特殊的波操纵能力。本文介绍了一种可同时利用共振散射和几何散射的埋地亚障，以衰减交通引起的低高频表面瑞利波。特别地，通过考虑垂直和水平埋于地下的元阻挡层单元，研究了元阻挡层的埋置排列如何影响其共振和几何散射机制。为此，建立了一个数值有限元模型，并通过与已有研究的比较验证了该模型的有效性。使用该模型，我们进行了参数化研究，以检查材料特性和超势垒尺寸对其衰减行为的影响。由于共振散射，低频瑞利波主要被垂直元障层反射；相反，它们主要被水平元障壁转化为折射体波。此外，水平元阻挡层的几何散射产生布拉格效应，可以反射更多的高频瑞利波，并诱导部分模式转换为横向体波。我们的系统研究将在一定程度上促进未来设计性能良好的衰减宽带瑞利波的元屏障。Design and sound absorption analysis of labyrinthine acoustic metamaterials based on fractal theoryDongXing Cao, LiMing Wang, JunRu Wang, XiangYing Guo, HaiTao Lidoi:10.1016/j.ijsolstr.2024.113121基于分形理论的迷宫式声学超材料设计与吸声分析Acoustic metamaterials exhibit exceptional sound absorption capabilities. This study introduces a fractal labyrinthine acoustic metamaterial (FLAM) designed for sound absorption analyses in a low-frequency range of 1–2000 Hz. The fractal curve is constructed through side substitution on an isosceles right triangle, which is chosen as the spatial recursive substructure due to its self-similarity. The FLAM model is then developed. With the thermal viscous losses considered in narrow channels, the sound absorption coefficient of this model is theoretically analyzed as the structural parameters significantly affect the sound absorption. A comprehensive analysis of low-frequency sound absorption performance is conducted for the first three orders, and the reconstruction of the structure with different combinations of fractal orders is examined to optimize the FLAM. The results show that the proposed FLAM achieves nearly perfect absorption in the 50–400 Hz range, with peak absorption coefficients of 0.99, 0.95, and 0.95 for the first three orders. The proposed FLAMs for the first three orders have total thicknesses of 0.032λ, 0.021λ, and 0.019λ, demonstrating excellent low-frequency sound absorption at deep sub-wavelength scales.声超材料具有卓越的吸声能力。本研究介绍了一种分形迷宫式声学超材料（FLAM），设计用于 1-2000 Hz 低频范围内的吸声分析。分形曲线是通过对等腰直角三角形进行边置换而构建的，由于其自相似性，我们选择等腰直角三角形作为空间递归子结构。然后建立 FLAM 模型。考虑到窄通道中的热粘性损失，对该模型的吸声系数进行了理论分析，因为结构参数对吸声有显著影响。对前三阶的低频吸声性能进行了全面分析，并研究了不同分形阶数组合的结构重构，以优化 FLAM。结果表明，所提出的 FLAM 在 50-400 Hz 范围内实现了近乎完美的吸声效果，前三阶的吸声系数峰值分别为 0.99、0.95 和 0.95。所提出的前三阶 FLAM 的总厚度分别为 0.032λ、0.021λ 和 0.019λ，显示了在深亚波长尺度上出色的低频吸声性能。Journal of the Mechanics and Physics of SolidsPremature jump-to-contact with elastic surfacesChuanli Yu, Zhaohe Daidoi:10.1016/j.jmps.2024.105919过早地与弹性表面接触Jump-to-contact is a commonly observed phenomenon in atomic force microscopy (AFM) measurements. It occurs when the AFM tip approaches the surface of the substrate, and the attractive forces—such as van der Waals forces—between the tip and the surface become sufficiently strong, causing the tip to jump toward the surface suddenly. Here, we investigate how the surface deformation affects the onset of jump-to-contact, and show that jump-to-contact happens prematurely in the deformable case (compared to the rigid case). We formulate this problem for surfaces that respond to external forces linearly and consider both retarded and non-retarded van der Waals forces. The jump-to-contact is investigated with linearly elastic substrates of arbitrary thicknesses. Specifically, we focus on small surface deformation relative to the tip–surface gap and perform a perturbation analysis for thin and thick substrates. Analytical solutions are obtained for the force or distance at which the jump occurs. These results should be useful for characterizing the strength and retardation behavior of van der Waals forces in soft materials and structures.跳接触是原子力显微镜（AFM）测量中常见的现象。当AFM尖端接近基底表面时，尖端和表面之间的吸引力（如范德华力）变得足够强，导致尖端突然向表面跳跃时，就会发生这种情况。在这里，我们研究了表面变形如何影响跳接触的开始，并表明在可变形情况下（与刚性情况相比），跳接触过早发生。我们将这个问题表述为对外力线性响应的曲面，并考虑延迟和非延迟范德华力。研究了任意厚度的线弹性衬底的跳变接触。具体来说，我们专注于相对于尖端表面间隙的小表面变形，并对薄基材和厚基材进行微扰分析。得到了跳跃发生时的力或距离的解析解。这些结果将有助于表征软材料和结构中范德华力的强度和延迟行为。Mechanics of MaterialsThe elastic properties of fiber-reinforced materials with imperfect interfacial bondings: Analytical approximations versus full-field simulationsValentin Gallican, Miroslav Zecevic, Ricardo A. Lebensohn, Martín I. Idiartdoi:10.1016/j.mechmat.2024.105185具有不完全界面连接的纤维增强材料的弹性特性：解析近似与全场模拟New analytical approximations are proposed for the linear elastic properties of fiber materials with imperfect interfacial bondings, across which displacements jump in proportion to the tractions, for finite volume fraction of reinforcements. The fibers are all parallel, isotropically distributed on the transverse plane, and of circular cross section. Elastic properties of both matrix and reinforcement can be arbitrary, but those of their interfacial bonding are restricted to a particular form of common use. Proposals rely on the original combined use of the Hashin–Shtrikman approximation for perfectly bonded systems and the equivalent inclusion concept adapted to the peculiar geometry of fibers. Three distinct approximations are considered which differ in the way the elastic properties of the interfacial bonding are averaged over the interfacial surface; they either involve an arithmetic, a harmonic, or a mixed average. Their accuracy is assessed by confronting them to full-field simulations generated with a Fast Fourier Transform-based algorithm suitably implemented to handle interfacial imperfections. Comparisons for transversely isotropic materials with monodisperse reinforcements confirm the superiority of the harmonic and mixed approximations over the more common arithmetic approximation. Overall, the mixed approximation is found to provide the most accurate estimates for a wide range of interfacial bondings and reinforcement contents. The approximations should therefore constitute a valuable ingredient in mean-field descriptions for fiber-reinforced materials incorporating interfacial deformation processes.对于有限体积分数的增强材料，提出了具有不完美界面连接的纤维材料的线弹性特性的新的解析近似，其中位移与牵引力成正比。纤维在横切面上呈各向同性平行分布，截面呈圆形。基体和增强材料的弹性性能可以是任意的，但它们的界面结合的弹性性能仅限于一种特殊的常用形式。提案依赖于对完美键合系统的Hashin-Shtrikman近似和适用于纤维特殊几何形状的等效包含概念的原始组合使用。考虑了三种不同的近似，它们在界面表面上平均界面键合的弹性性能的方式不同；它们要么是算术，要么是谐波，要么是混合平均。通过将其与基于快速傅立叶变换的算法生成的全场模拟进行比较，以评估其准确性，该算法适用于处理界面缺陷。对具有单分散增强材料的横向各向同性材料的比较证实了谐波近似和混合近似优于更常见的算术近似。总的来说，混合近似可以为大范围的界面结合和强化含量提供最准确的估计。因此，近似应构成包含界面变形过程的纤维增强材料的平均场描述的有价值的成分。International Journal of PlasticityHeterogeneous phase deformation in a dual-phase tungsten alloy mediated by the tungsten/matrix interface: insights from compression experiments and crystal plasticity modelingZuosheng Li, Lei Zhang, Bob Svendsen, Quanyi Xue, Sai Tang, Yunzhu Ma, Wensheng Liudoi:10.1016/j.ijplas.2024.104156钨/基体界面介导的双相钨合金的非均匀相变形：来自压缩实验和晶体塑性建模的见解Tungsten heavy alloy (WHA) is a typical multiphase alloy material consisting of hard tungsten (W) and soft matrix (γ) phases. When loaded, the two phases deform quite differently due to the large difference in their mechanical properties. At present, our understanding of phase deformation and behavior in the multiphase context is relatively poor compared to the single phase case. Such insight is necessary, however, for the design of multiphase alloys having optimal phase microstructure and corresponding material behavior. By combining mechanical testing and crystal plasticity modeling, the relationship between phase microstructure and multiphase alloy deformation behavior is systematically investigated in this work. The results demonstrate that deformation in the W and γ phases is quite different and related to the contrast in material properties between the two phases. Deformation heterogeneity in the multiphase alloy is characterized by the strain gradient near/across the W/γ interface and differences in phase deformation states in relation to the contrast in phase material properties and phase volume fraction. It is found that dislocation pile-up and twinning are the main mechanisms mediating heterogeneous deformation in the region around W/γ interfaces. Based on this insight, a novel design strategy for multiphase alloys is proposed based on optimization of the contrast in phase mechanical properties and the phase volume fractions. This strategy can be employed to design new tungsten alloys and other multi-phase alloys.重钨合金（WHA）是一种典型的由硬钨(W)相和软基体（γ）相组成的多相合金材料。加载时，由于力学性能的巨大差异，两相的变形完全不同。目前，与单相情况相比，我们对多相环境下的相变形和行为的理解相对较差。然而，这种洞察力对于设计具有最佳相组织和相应材料性能的多相合金是必要的。本文采用力学试验和晶体塑性建模相结合的方法，系统研究了相组织与多相合金变形行为的关系。结果表明，W相和γ相的变形差异较大，这与两相材料性能的差异有关。多相合金的变形不均匀性表现为W/γ界面附近/两侧的应变梯度，以及与相材料性能和相体积分数的差异有关的相变形状态的差异。发现位错堆积和孪晶是W/γ界面周围非均质变形的主要机制。在此基础上，提出了一种基于相力学性能对比和相体积分数优化的多相合金设计策略。该方法可用于设计新型钨合金和其他多相合金。A generalized, computationally versatile plasticity model framework - Part II: Theory and verification focusing on shear anisotropyYong Hou, Junying Min, Hyung-Rim Lee, Jinjin Ha, Namsu Park, Myoung-Gyu Leedoi:10.1016/j.ijplas.2024.104158 一个广义的，计算通用的塑性模型框架-第二部分：关注剪切各向异性的理论和验证Shear-dominated deformation (SHDD) is pivotal in sheet metal forming; however, comprehensive modeling of plastic anisotropy in SHDD, specifically shear anisotropy considering both yield stress and plastic flow, has been inadequately addressed in existing literature. In this work, a generalized constitutive framework is introduced on the basis of stress triaxiality-dependent state variable to accurately emulate plastic anisotropy and the physics-based shear constraint in SHDD. The framework is capable to seamlessly integrate with existing yield criteria, preserving computational efficiency and versatility. Notably, the yield function, anisotropic parameters, and their optimization or analytical determination for the non-shear deformation state remain unaltered. When integrated with the Hill48 yield function, featuring either one or two anisotropic parameters within the generalized constitutive framework, precise characterization of yield strength and plastic flow in SHDD is achieved. The applicability of the framework extends to various anisotropic yield functions such as the widely employed Yld2k-2d and the sixth-order polynomial (Poly6) function as a class of associated flow rule-based yield functions, and one non-quadratic yield function for non-associated flow rule scenarios. Experimental validation with two engineering sheet metals, high-strength dual-phase steel DP980 and high-strength aluminum alloy AA7075-T6, was conducted. Comparative analyses with several recently proposed yield criteria, especially Poly6-18p, highlighted the efficiency of the proposed constitutive framework. Furthermore, this study explores intrinsic shear constraints, particularly the absence of through-thickness strains under in-plane shear stress. Additionally, it offers an enhanced description of plastic anisotropy in shear yield stress within the general framework, providing valuable insights into the complexities of SHDD.剪切主导变形（SHDD）是板料成形的关键；然而，对SHDD中塑性各向异性的综合建模，特别是考虑屈服应力和塑性流动的剪切各向异性，在现有文献中还没有得到充分的解决。本文在应力三轴相关状态变量的基础上引入广义本构框架，以准确模拟SHDD中的塑性各向异性和基于物理的剪切约束。该框架能够与现有的产量标准无缝集成，保持计算效率和多功能性。值得注意的是，非剪切变形状态的屈服函数、各向异性参数及其优化或分析确定保持不变。当与广义本构框架内具有一个或两个各向异性参数的Hill48屈服函数相结合时，可以精确表征SHDD的屈服强度和塑性流动。该框架的适用性扩展到各种各向异性屈服函数，如广泛使用的Yld2k-2d和六阶多项式（Poly6）函数作为一类基于关联流规则的屈服函数，以及一个用于非关联流规则场景的非二次屈服函数。采用高强度双相钢DP980和高强度铝合金AA7075-T6两种工程板材进行了试验验证。与最近提出的几种屈服标准，特别是Poly6-18p的比较分析，突出了所提出的本构框架的效率。此外，本研究还探讨了内在剪切约束，特别是在面内剪切应力下不存在贯穿厚度的应变。此外，它还在总体框架内增强了剪切屈服应力的塑性各向异性描述，为了解SHDD的复杂性提供了有价值的见解。Thin-Walled StructuresOn impact response and damage tolerance of adhesively bonded joints - An experimental and numerical studyYang Wei, Gang Zheng, Quantian Luo, Qing Li, Guangyong Sundoi:10.1016/j.tws.2024.112606 粘接接头冲击响应与损伤容限的实验与数值研究Composite adhesive bonding offers more possibilities for advanced structures. However, its maintenance and repair may cause enormous cost in service and operation. To avoid unnecessary replacement of parts, it is essential to have more comprehensive understanding of damage tolerance of bonded structures. This study aims to investigate impact responses and damage tolerance of adhesively bonded joints (ABJs) by experimental and finite element analysis methods. First, the dedicated impact tests on a specimen with fixed boundary conditions is carried out to characterize the mechanical responses of ABJs to real service conditions. Second, the impact resistance of rigid and flexible adhesives is compared, and the flexible adhesive is found to be a better choice. Third, the effects of different substrate materials on damage tolerance are scrutinized. The residual strength after impact is evaluated using the lap-shear strength as an indicator. The experimental results indicate that the CFRP-aluminum joint with its CFRP plates to withstand impact is a recommended configuration for bearing impact load. It is found that based on the modified Arcan calibration experiment, the non-priori finite element model can accurately predict the out-of-plane impact and post-impact uniaxial tensile behaviors. This study is anticipated to provide key impact characteristics and reliable damage tolerance for more extensive applications of adhesively bonded joints in engineering practice.复合胶粘接为高级结构提供了更多的可能性。然而，其维护和维修在使用和运行中会造成巨大的成本。为了避免不必要的零件更换，有必要对粘结结构的损伤容限有更全面的了解。本研究旨在通过实验和有限元分析方法研究粘接接头（ABJs）的冲击响应和损伤容限。首先，对固定边界条件下的试样进行了专用冲击试验，表征了abj在实际使用条件下的力学响应。其次，对刚性和柔性胶粘剂的抗冲击性进行比较，发现柔性胶粘剂是更好的选择。第三，研究了不同基底材料对损伤容限的影响。以搭剪强度为指标，评价了冲击后的残余强度。试验结果表明，CFRP-铝节点及其CFRP板承受冲击是承载冲击载荷的推荐配置。结果表明，基于修正Arcan标定实验的非先验有限元模型能够较准确地预测面外冲击和冲击后的单轴拉伸行为。该研究有望为粘接接头在工程实践中的更广泛应用提供关键的冲击特性和可靠的损伤容限。Non-destructive buckling load estimation of oblate ellipsoidal domes using the vibration correlation techniqueGopikrishna R., G. Raju, Ramkrishna D.doi:10.1016/j.tws.2024.112612基于振动相关技术的扁椭球圆顶非破坏性屈曲载荷估计In this paper, experimental and numerical studies based on the vibration correlation technique (VCT) are employed to non-destructively determine the buckling load of oblate ellipsoidal domes subjected to external pressure loading. Two nominally identical isotropic oblate ellipsoidal domes are fabricated, and experiments are conducted using specially designed fixtures and a hydraulic system for applying pressure. The dome’s deformation, strains, and modal response are measured at different pressure loads and analyzed. Conventional and modified VCT approaches are used to evaluate the buckling load. The experimental buckling results are compared with VCT predictions and the effect of various factors like mode number of interest, reference natural frequency, number of data points, and reference critical buckling load are studied. The results from this work serve as a validation for the applicability of VCT in predicting the buckling load of oblate ellipsoidal dome structures.本文采用基于振动相关技术（VCT）的实验和数值研究方法，对外压载荷作用下扁椭球体穹顶的屈曲载荷进行了无损确定。制作了两个名义上相同的各向同性扁形椭球体，并使用专门设计的夹具和液压系统施加压力进行了实验。对穹顶在不同压力载荷下的变形、应变和模态响应进行了测量和分析。采用传统的和改进的VCT方法来评估屈曲载荷。将实验屈曲结果与VCT预测结果进行了比较，研究了感兴趣模态数、参考固有频率、数据点数和参考临界屈曲载荷等因素的影响。研究结果验证了VCT在扁椭球球圆顶结构屈曲载荷预测中的适用性。An Equivalent Average Shear Stress Yield Criterion Based on Simpson's Numerical Integration Rule and its Application in Burst Pressure Analysis of Thin-Walled PipelinesYongsheng Shi, Yanhui Qie, Jinhua Song, Yutong Lidoi:10.1016/j.tws.2024.112613基于Simpson数值积分规则的等效平均剪应力屈服准则及其在薄壁管道破裂压力分析中的应用Pipelines are a crucial transportation infrastructure for the long-distance transport of natural gas, oil, and other hydrocarbons, typically conducted through thin-walled pipes (D/t≥20). Accurate prediction of the burst pressure of thin-walled pipelines is essential for their safe and reliable operation. To enhance the prediction accuracy of the burst pressure for defect-free, straight, thin-walled pipes, a new numerical integration yield criterion was proposed between the Tresca and Mises criteria, using the mean value of Simpson's numerical integration (MSI) as the equivalent shear stress. A new burst pressure prediction formula was then constructed using the MSI yield criterion. The burst pressure predictions based on different yield criteria were compared with experimental data. Additionally, the burst pressure curves of the new prediction formula were plotted, and the relative errors between the new prediction formula and four existing prediction formulas were analyzed and compared. The results indicate that the new burst pressure prediction formula using the MSI yield criterion closely matches the experimental data, with the best relative error result within a confidence interval of ±1.3%. The Lord parameter curve and plane stress curve of the MSI yield criterion exhibit good consistency with the experimental data of various ductile metal materials. The new burst pressure formula established by incorporating the MSI criterion provides a safe, economical, and reliable theoretical foundation for the design, manufacture, inspection, and safety assessment of thin-walled pipelines in production practice.管道是天然气、石油和其他碳氢化合物长距离运输的重要基础设施，通常通过薄壁管道（D/t≥20）进行。准确预测薄壁管道的爆裂压力对于管道的安全可靠运行至关重要。为了提高无缺陷、直管、薄壁管道的破裂压力预测精度，在Tresca准则和Mises准则之间提出了一种新的数值积分屈服准则，使用辛普森数值积分（MSI）的平均值作为等效剪切应力。然后使用MSI屈服准则构建了一个新的破裂压力预测公式。将基于不同屈服准则的爆裂压力预测值与实验数据进行比较。此外，绘制了新预测公式的爆裂压力曲线，并分析和比较了新预测公式与四个现有预测公式之间的相对误差。结果表明，使用MSI屈服准则的新爆裂压力预测公式与实验数据非常吻合，置信区间为±1.3%时，相对误差结果最佳。MSI屈服准则的洛德参数曲线和面应力曲线与各种韧性金属材料的实验数据具有很好的一致性。通过引入MSI准则建立的新爆裂压力公式为生产实践中薄壁管道的设计、制造、检验和安全评估提供了安全、经济、可靠的理论基础。Analysis and evaluation on residual impact resistance of CFST composite frames under column removal scenarioJing-Xuan Wang, Han-Jun Li, Shan Gaodoi:10.1016/j.tws.2024.112624钢管混凝土组合框架拆柱残余抗冲击性能分析与评价To investigate and evaluate the dynamic response and residual impact resistance of CFST (concrete-filled steel tubular) composite frames after the failure of vertical load-resisting components, two 1/4-scaled two-storey and two-span CFST composite subframes under the penultimate column and corner column failure conditions were tested in three consecutive impacts. The tests results show that the substructures under the penultimate column and corner column failure conditions after being statically loaded to 360 mm can both resist the three consecutive impacts. The aggravation of the cracks of the steel beams and the crush of the concrete slabs at the connections area were observed after the impacts. As the impact energy of three impacts increases, the average impact force of both two specimens increases and the substructure with penultimate column failure shows better anti-impact capacity than the specimen with corner column failure. The finite element model analysis shows that the damage and energy consumption of the structures under impact loading primarily concentrate on the failed span and the impacted storey, where the ring plate connections are the most dominant energy-consuming components. Over 75% of the impact resistance is provided by the flexural action of the composite beams. After being statically loaded to 360 mm, the structures can still resist the impacts which equal to 20.7% and 18.5% of the mass of the upper slab in the structures with the penultimate column and corner column failure, respectively. Additionally, a simplified prediction method is proposed for the residual anti-impact energy-consuming capacity of the substructures with column failure which is found to be negatively linearly related to the initial vertical displacement.为了研究和评价钢管混凝土组合框架竖向荷载构件破坏后的动力响应和残余抗冲击性能，对2个1/4比例的两层两跨钢管混凝土组合框架在倒数柱和角柱破坏条件下进行了连续3次冲击试验。试验结果表明，静载至360 mm后，倒数柱和角柱破坏条件下的子结构均能抵抗连续三次冲击。撞击后，梁柱裂缝加剧，连接区混凝土板开裂。随着三次冲击能量的增大，两个试件的平均冲击力均增大，倒数第二柱破坏的下部结构抗冲击能力优于角柱破坏的下部结构。有限元模型分析表明，结构在冲击荷载作用下的损伤和能耗主要集中在失效跨和受冲击层，其中环板连接是耗能最大的构件。超过75%的抗冲击性是由组合梁的弯曲作用提供的。静力加载至360 mm后，结构仍能承受相当于上板质量20.7%和18.5%的冲击，其中倒数第二柱和角柱破坏结构。此外，提出了柱破坏子结构剩余抗冲击耗能能力的简化预测方法，发现柱破坏子结构剩余抗冲击耗能能力与初始竖向位移呈负线性关系。A temperature-regulated multi-material compression-torsion metamaterial with local bistabilityHao Chen, Yongtao Yao, Yanju Liu, Wenfeng Biandoi:10.1016/j.tws.2024.112629 具有局部双稳性的温度可调多材料压缩-扭转超材料In this paper, based on the compression-torsion coupling structure, we designed and fabricated a structure that exhibits a temperature-controlled local bistability phenomenon during uniaxial compression at different temperatures. In the structure, based on the quadrilateral rigid frames, the flexible connecting bands are hinged to the frames by pins, and the shape memory polymer inclined struts are bonded to the frames. The compression-torsion coupling causes the bend of the inclined struts and the rotation of the rigid frames, then causing the connecting bands to post-buckling. The inclined struts can adjust and control the deformation process under thermal loads, because the modulus of the shape memory polymer is controlled by temperature, so that the deformation of the structure is reversible/irreversible under programmable temperature/displacement loads. The analytical model and numerical simulation show that the local bistability can be achieved under temperature control and different boundary conditions. An assembled metamaterial structure is fabricated by combining 3D printed parts. The relationships between the reversibility/irreversibility of the structural deformation and temperature/displacement loads are verified by experiments. The local bistable phenomenon enables the structure to remember the history of the load, providing inspiration for new functional designs in the fields of intelligent memory, encoding display, and vibration energy absorption.本文在压缩-扭转耦合结构的基础上，设计并制造了一种在不同温度下单轴压缩时出现温控局部双稳现象的结构。在该结构中，基于四边形刚性框架，将柔性连接带通过销钉铰接在框架上，并将形状记忆聚合物倾斜支柱粘接在框架上。压扭联轴器的作用是引起斜杆的弯曲和刚性框架的转动，从而引起连接带的后屈曲。由于形状记忆聚合物的模量是由温度控制的，因此斜支撑可以调节和控制热载荷下的变形过程，使得结构在可编程温度/位移载荷下的变形是可逆/不可逆的。解析模型和数值模拟表明，在温度控制和不同边界条件下，可以实现局部双稳态。将3D打印的部件组合在一起，组装成一个超材料结构。通过实验验证了结构变形的可逆性/不可逆性与温度/位移荷载之间的关系。局部双稳现象使结构能够记住载荷的历史，为智能记忆、编码显示、振动能量吸收等领域的新功能设计提供灵感。Enhanced energy absorption and mechanical properties of porous Ti-6Al-4V alloys with gradient disordered cells fabricated by laser powder bed fusionRusheng Zhao, Shiyue Guo, Jian Wang, Bin Li, Fan Zhang, Donggen Yang, Xuezheng Yue, Xiangyu Guo, Huiling Tangdoi:10.1016/j.tws.2024.112632激光粉末床熔合制备梯度无序多孔Ti-6Al-4V合金的吸能性能和力学性能Additive manufacturing (AM) has revolutionized the production of porous metals, greatly improving control over their structural properties and offering unprecedented advantages in lightweight applications and energy absorption. Balancing energy absorption and compressive strength in ordered and disordered porous structures is challenging due to shear deformation and deformation mechanisms. This study investigates the mechanical and energy absorption properties of porous Ti-6Al-4V alloys with gradient disordered cells fabricated using laser powder bed fusion (LPBF). The compressive response of samples with different regularities (R) and varying layers of disordered cells was analyzed through quasi-static compression experiments and finite element simulations. The results indicate that introducing a disordered cell gradient significantly enhances energy absorption by preventing the formation of shear bands observed in porous structures with ordered cell structures. When the regularity (R) is 0.8, 0.4, and 0.2 with one or two layers of disordered cells, mechanical properties are optimized and characterized by a balance between compressive strength and energy absorption. It is significant that, while preserving or enhancing compressive strength, the energy absorption of the material can be augmented substantially. Specifically, porous Ti-6Al-4V (R = 0.8, L4) achieves an energy absorption increase of up to 154.9kJ/m³, which represents a dramatic enhancement of approximately 245.0% over the regular porous structure (R = 0 or L0), which absorbs only 44.9 kJ/m³. Compared to ordered and disordered porous structures, the disordered cell gradient demonstrates significant potential in tuning the mechanical properties of porous metals, thereby advancing their applications in aerospace, biomedical, and protective fields.增材制造（AM）彻底改变了多孔金属的生产，极大地改善了对其结构性能的控制，并在轻量化应用和能量吸收方面提供了前所未有的优势。由于剪切变形和变形机制，平衡有序和无序多孔结构的能量吸收和抗压强度具有挑战性。研究了激光粉末床熔合法制备梯度无序晶胞多孔Ti-6Al-4V合金的力学性能和吸能性能。通过准静态压缩实验和有限元模拟，分析了不同规则度(R)和不同无序单元层数的试样的压缩响应。结果表明，引入无序的细胞梯度可以显著提高能量吸收，从而阻止了有序细胞结构中剪切带的形成。当不规则性(R)为0.8、0.4和0.2时，一层或两层无序胞元，力学性能优化，表现为抗压强度和能量吸收平衡。重要的是，在保持或提高抗压强度的同时，材料的能量吸收可以大大增加。具体来说，多孔Ti-6Al-4V （R = 0.8,L4）的能量吸收增加了154.9kJ/m³，比常规多孔结构（R = 0或L0）的能量吸收增加了约245.0%，而常规多孔结构的能量吸收仅为44.9 kJ/m³。与有序和无序多孔结构相比，无序细胞梯度在调节多孔金属的力学性能方面显示出巨大的潜力，从而促进了它们在航空航天、生物医学和防护领域的应用。Full active counter-roller spinning for thin-walled cylinders: macroscopic deformation mechanism, mesoscopic texture evolution, and forming performance strengtheningNing Yang, Zhishun Li, Lijun Zhang, Lukuan Li, Su Liu, Xianfeng Chen, Hang Wang, Shen Fan, Shuqin Fan, Jiayi Xudoi:10.1016/j.tws.2024.112634薄壁圆筒全主动反辊旋压：宏观变形机理、细观织构演变及成形性能强化The reliability and lightweight of hydrogen high-pressure storage present pressing global challenges. The forming mechanism of a novel full active counter-roller spinning (FACRS) process for thin-walled cylinders is studied from the perspective of macro-meso coupling. This innovative process holds promise as a replacement for conventional mandrel spinning, enabling enhanced integration of form and property in manufacturing hydrogen bottle liners. Employing optimal Latin hypercube sampling, a response surface model is constructed for forming consistency (λ) of inner and outer surfaces, yielding an optimal set of process parameters under the Hooke-Jeeves algorithm. The resulting spun parts exhibit a more balanced and superior performance. A macro-meso gradual cross-scale coupling simulation methodology is proposed, revealing that the process is characterized by the initial aggregation and subsequent reinforcement of texture, culminating in the formation of a "soft" rotated cubic texture, which still faces impediments or diminishes the orientation of texture. It is demonstrated that the evolution of texture is the result of the interactive coordination of various slip systems. Furthermore, the FACRS experiments and performance tests indicate that while enhancing the axial and circumferential mechanical properties of the spun parts, it also reduces material anisotropy. The grain refinement effect of the process has also led to a more uniform distribution of dimples on the fracture surface. The surface performance of the final spun parts improves by 60.11%. These enhancements can be attributed to the combined effects of improved forming consistency, coordinated action of slip systems, and grain refinement. These results deepen the understanding of the macro-meso deformation mechanisms underlying the novel process, providing valuable insights for further advancements in counter-roller spinning technology.高压储氢的可靠性和轻量化是全球面临的紧迫挑战。从宏细观耦合的角度研究了薄壁圆筒全主动反辊旋压成形机理。这种创新的工艺有望取代传统的芯棒纺丝，使制造氢瓶衬垫的形式和性能得到增强。采用最优拉丁超立方体采样，构造了内外曲面形成一致性（λ）的响应面模型，得到了Hooke-Jeeves算法下的最优工艺参数集。所得到的纺丝部件表现出更加平衡和优越的性能。提出了一种宏观-中观渐进的跨尺度耦合模拟方法，揭示了该过程的特征是纹理的初始聚集和随后的增强，最终形成“软”旋转立方体纹理，该纹理仍然面临阻碍或削弱纹理的取向。结果表明，织构的演化是各滑移体系相互作用协调的结果。此外，FACRS实验和性能测试表明，在提高旋压件轴向和周向力学性能的同时，也降低了材料的各向异性。该工艺的晶粒细化作用也使得断口表面的韧窝分布更加均匀。最终成形零件的表面性能提高了60.11%。这些增强可归因于形成一致性的改善、滑移系统的协调作用和晶粒细化的综合作用。这些结果加深了对新工艺背后的宏观-细观变形机制的理解，为反罗拉纺丝技术的进一步发展提供了有价值的见解。来源：复合材料力学仿真Composites FEM
