【新文速递】2024年8月30日固体力学SCI期刊最新文章

 

今日更新：International Journal of Solids and Structures 1 篇，Journal of the Mechanics and Physics of Solids 4 篇，Mechanics of Materials 3 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 6 篇

International Journal of Solids and Structures

Effect of interface type on deformation mechanisms of γ-TiAl alloy under different temperatures and strain rates by molecular dynamics simulation

Junqin Shi, Lulu Xu, Yang Lu, Lulu Li, Biqiang Chen, Junjie Lu

doi:10.1016/j.ijsolstr.2024.113051

不同温度和应变速率下界面类型对γ-TiAl合金变形机制的影响

Crystalline interface plays a significant role in strengthening lamellar γ-TiAl alloys through reconciling the strength and ductility. Herein, the effects of temperature and strain rate on the tensile deformation of three lamellar γ-TiAl interface models are investigated by molecular dynamics simulations. The three interfaces, pseudo twin (PT), rotational boundary (RB), and true twin (TT), exhibit different tensile responses due to the different interface effects: TT interface only acts as a barrier of dislocation traversing to facilitate crack extension; PT interface acts as both dislocation barrier and emission source and has a stronger release of strain energy than TT interface, retarding the crack extension; RB interface can retard and resist crack extension due to the blunting and deflection of the crack tip and the best interface geometry compatibility. The defect evolution indicates that the elevated temperature suppresses dislocation propagation at low strain rate, while the high strain rate causes small lamellar stacking faults and slit-shaped holes along tensile direction at low temperature. In addition, the dual conditions of high strain rate and low temperature induce the phase transition from FCC to BCC and then BCC to HCP. These findings provide a specific insight to understand the atomistic mechanism of interface-mediated deformation.

晶体界面通过协调γ-TiAl合金的强度和延展性，在强化层状γ-TiAl合金中起着重要的作用。本文采用分子动力学方法研究了温度和应变速率对三种层状γ-TiAl界面模型拉伸变形的影响。伪孪晶(PT)、旋转边界(RB)和真孪晶(TT)三种界面由于界面效应不同，表现出不同的拉伸响应:TT界面仅作为位错穿越的屏障，促进裂纹扩展;PT界面既是位错屏障又是发射源，其应变能释放比TT界面更强，减缓了裂纹扩展;RB界面由于裂纹尖端的钝化和偏转，具有良好的界面几何相容性，可以延缓和抵抗裂纹扩展。缺陷演化表明，在低应变速率下，升高的温度抑制位错的扩展，而在低温下，高应变速率导致沿拉伸方向的小片层堆积错误和狭缝状孔洞。此外，高应变速率和低温的双重条件诱导了从FCC到BCC再到BCC到HCP的相变。这些发现为理解界面介导变形的原子机制提供了具体的见解。

Journal of the Mechanics and Physics of Solids

Phase-field simulations of ferro-electro-elasticity in model polycrystals with implications for phenomenological descriptions of bulk perovskite ceramics

Roman Indergand, Dennis M. Kochmann, Martín I. Idiart

doi:10.1016/j.jmps.2024.105831

模型多晶中铁电弹性的相场模拟与块状钙钛矿陶瓷的现象学描述

We investigate the role of polycrystalline disorder on the effective ferro-electro-elastic behavior of perovskite ferroelectric ceramics under electro-mechanical loading. Assuming random initial grain orientations, we use high-resolution phase-field simulations and periodic homogenization of two-dimensional model polycrystals to study the evolution of the domain microstructure within and across grains as well as the resulting effective, macroscopic polarization and strain fields under loading. The number of randomly-oriented grains in simulations, at fixed grain size and fixed numerical resolution per grain, is used to control the polycrystalline disorder. Results indicate that, when the polycrystalline samples are sufficiently disordered (i.e., when sufficiently many randomly-oriented grains are considered), their effective electromechanical response under uniaxial compression is stable, and the concomitant polarization and deformation are always aligned with the mechanical load. Thus, the present study supports the viewpoint that polycrystalline disorder in bulk perovskite ceramics stabilizes the overall ferro-electro-elastic response despite the underlying nonconvex polarization energy landscape.

我们研究了多晶无序对钙钛矿铁电陶瓷在机电载荷下的有效铁电弹性行为的影响。假设初始晶粒取向随机，我们使用高分辨率相场模拟和二维模型多晶的周期性均匀化来研究晶粒内和晶粒间的畴微观结构演变，以及由此产生的有效宏观极化和应变场。在固定晶粒尺寸和每个晶粒的固定数值分辨率下，模拟中随机取向晶粒的数量被用来控制多晶无序。结果表明，当多晶样品足够无序(即考虑足够多的随机取向晶粒)时，其在单轴压缩下的有效机电响应是稳定的，并且伴随的极化和变形总是与机械载荷对齐。因此，本研究支持这样的观点:尽管存在潜在的非凸极化能量景观，但大块钙钛矿陶瓷中的多晶无序稳定了整体铁电弹性响应。

Imaging the intramuscular pressure of living muscles with shear waves

Weiqiang Xu, Yang Zheng, Ziyin Yin, Yuxuan Jiang, Zhaoyi Zhang, Shiyu Ma, Yanping Cao

doi:10.1016/j.jmps.2024.105834

用横波成像活体肌肉的肌内压力

Shear wave elastography (SWE) is an innovative method that allows for the nondestructive and quantitative characterization of muscular mechanical properties. This method finds extensive utility in fields such as sports medicine, sports rehabilitation, and the diagnosis of muscle-related ailments. Existing studies have demonstrated the promise of SWE in probing intramuscular pressure (IMP), a factor intimately tied to muscular physiological functions and the onset of certain diseases. Nonetheless, there remains a lack of a SWE method grounded in an appropriate biomechanical model capable of effectively imaging IMP in vivo. Addressing this issue, we propose a shear wave imaging method relaying on a porohyperelastic model encompassing well-defined parameters for both muscular active behavior and intramuscular pressure. Drawing upon wave motion analysis, we establish a correlation between shear wave velocities and IMP in analytical form. This theoretical solution on one hand help understand the interplay between IMP and muscle active stress and the impact of muscle contraction on IMP. On the other hand, it enables us to develop an elastography method to assess IMP in vivo. We conducted a series of experiments to underscore the applicability of our theory and elastography method. Ex vivo experiments were performed on porcine muscles, while in vivo tests were carried out on human skeletal muscles. The results from the ex vivo tests validate the efficacy of our method. Meanwhile, the in vivo outcomes suggest that our approach holds potential to assess the variation of IMP with muscle fatigue and injuries, inspect intramuscular injections, and diagnose acute and chronic compartment syndrome.

横波弹性成像(SWE)是一种创新的方法，允许无损和定量表征肌肉力学性能。这种方法在运动医学、运动康复和肌肉相关疾病的诊断等领域有着广泛的应用。现有的研究已经证明了SWE在探测肌内压(IMP)方面的前景，IMP是一个与肌肉生理功能和某些疾病发病密切相关的因素。尽管如此，仍然缺乏一种基于适当的生物力学模型的SWE方法，该模型能够有效地对IMP进行体内成像。为了解决这个问题，我们提出了一种基于孔隙超弹性模型的剪切波成像方法，该模型包含了肌肉活动行为和肌内压力的明确参数。根据波动分析，我们以解析的形式建立了横波速度与IMP之间的关系。这一理论解决方案一方面有助于理解IMP与肌肉活动应力之间的相互作用以及肌肉收缩对IMP的影响，另一方面，它使我们能够开发一种弹性成像方法来评估IMP在体内的作用。我们进行了一系列的实验，以强调我们的理论和弹性学方法的适用性。离体实验在猪肌肉上进行，在体实验在人骨骼肌上进行。体外实验的结果验证了我们方法的有效性。同时，体内结果表明，我们的方法有潜力评估IMP随肌肉疲劳和损伤的变化，检查肌内注射，诊断急性和慢性筋膜室综合征。

A crystal plasticity-based creep model considering the concurrent evolution of point defect, dislocation, grain boundary, and void

Zhun Liang, Changmeng Liu, Yinan Cui

doi:10.1016/j.jmps.2024.105836

考虑点缺陷、位错、晶界和空洞同时演化的晶体塑性蠕变模型

Creep poses a significant threat to the integrity and longevity of structural components at high-temperature. The most current understanding of creep mainly focuses on the coupled dynamics of point defects and dislocation, which may well describe the first and second stage of creep. However, the behavior of the three stages of creep is jointly controlled by point defect (vacancy) diffusion, dislocation glide, dislocation climb, grain boundary (GB) sliding, and void evolution. A critical knowledge gap still exists regarding how these different creep mechanisms are simultaneously coupled during the three stages of creep. In this work, a multi-physical mechanisms-based crystal plasticity model is proposed to consider the concurrent evolution of point defect, dislocation, GB, and void based on a unified thermodynamic framework. In-situ scanning electron microscope creep experiments and macroscopic creep experiments of Ti-6Al-4V were conducted to validate our model. The in-situ creep experiment directly revealed the GB sliding creep failure behavior of Ti-6Al-4V for the first time. The proposed model well predicts both the microscopic and macroscopic experimental behavior of creep. The contribution of different microstructure evolutions is discussed, and a phase diagram of the dominated creep mechanism is obtained. An in-depth analysis was conducted on the coupling effects and microstructure characteristics of different creep mechanisms. This work not only deepens our understanding of the micro creep mechanism but also offers valuable insights for designing materials with specific microstructures to enhance their creep resistance.

在高温下，蠕变对结构构件的完整性和寿命构成了严重威胁。目前对蠕变的理解主要集中在点缺陷和位错的耦合动力学上，这可以很好地描述蠕变的第一阶段和第二阶段。而三个阶段的蠕变行为受点缺陷(空位)扩散、位错滑动、位错攀升、晶界(GB)滑动和空洞演化的共同控制。关于这些不同的蠕变机制如何在蠕变的三个阶段同时耦合，仍然存在一个关键的知识差距。本文提出了一种基于多物理机制的晶体塑性模型，在统一的热力学框架下考虑了点缺陷、位错、GB和空洞的同步演化。通过原位扫描电镜蠕变实验和宏观蠕变实验验证了该模型的有效性。原位蠕变试验首次直接揭示了Ti-6Al-4V的GB滑动蠕变破坏行为。该模型能较好地预测蠕变的微观和宏观试验行为。讨论了不同微观组织演化的贡献，得到了主导蠕变机理的相图。深入分析了不同蠕变机制的耦合效应和微观结构特征。这项工作不仅加深了我们对微观蠕变机理的理解，而且为设计具有特定微观结构的材料以增强其抗蠕变能力提供了有价值的见解。

The importance of a full chemo-poro-mechanical coupling for the modeling of subcutaneous injections

Ludovic Gil, Michel Jabbour, Nicolas Triantafyllidis

doi:10.1016/j.jmps.2024.105833

充分的化学-孔隙-力学耦合对皮下注射建模的重要性

Modeling of subcutaneous injections in soft adipose tissue – a common way to administer pharmaceutical medication – is a challenging multiphysics problem which has recently attracted the attention of the engineering community, as it could help optimize medical devices and treatments. The underlying continuum mechanics of this process is complex and involves finite strain poro-mechanics – where a viscous fluid, containing different charged species, is injected into a porous viscoelastic matrix and absorbed by blood and lymph vessels – as well as electrochemistry, that generates osmotic pressure due to electrical charges attached to the tissue. In this paper, we present a chemo-mechanical model of subcutaneous injections that accounts for the diffusion of electrically charged chemical species – contained in the interstitial fluid – into the tissue, blood and lymph vessels. This work provides the methodology to derive a general theory accounting for the electro-chemo-poro-mechanical couplings in a thermodynamically consistent framework, avoiding phenomenological biases or inconsistencies likely to arise in the derivation of nonlinear theories with many couplings. To motivate its use for the modeling of subcutaneous injections, it is complemented by a simplified, linearized boundary value problem that illustrates the importance of considering these couplings for the prediction of subcutaneous injections key performance indicators.

软脂肪组织皮下注射的建模是一种常见的给药方式，是一个具有挑战性的多物理场问题，最近引起了工程界的注意，因为它可以帮助优化医疗设备和治疗。这一过程的潜在连续力学是复杂的，涉及有限应变孔隙力学(含有不同带电物质的粘性流体被注入多孔粘弹性基质并被血液和淋巴管吸收)和电化学(由于附着在组织上的电荷而产生渗透压)。在本文中，我们提出了一种皮下注射的化学力学模型，该模型解释了间质液中带电化学物质向组织、血液和淋巴管中的扩散。这项工作提供了在热力学一致的框架中推导出电化学-孔隙-机械耦合的一般理论的方法，避免了在推导具有许多耦合的非线性理论时可能出现的现象学偏差或不一致。为了激励其用于皮下注射建模，它被一个简化的、线性化的边值问题所补充，说明了考虑这些耦合对于预测皮下注射关键性能指标的重要性。

Mechanics of Materials

AA5754 aluminium alloy springback reduction by Post Forming Electro Plastic Effect (PFEPE)

Jokin Lozares, Nagore Otegi, Javier Trinidad, Manex Barrenetxea, Iosu Aizpuru, Pello Jimbert, Joseba Mendiguren

doi:10.1016/j.mechmat.2024.105136

后成形电塑性效应(PFEPE)降低AA5754铝合金回弹

Post Forming Electro Plastic Effect (PFEPE) has been proposed as a promising technology for mitigating forming forces and addressing springback challenges in the metal forming industry. However, several research gaps remain unaddressed for the industrialization of this technology. Firstly, there is a lack of experimental validation regarding the impact of stress reduction on springback. Secondly, the potential effect of the skin-effect on the current metrics of stress reduction needs to be evaluated. Additionally, a post-forming electrically assisted elastoplastic material model is necessary for further technology development in stamping processes. This study tackles these challenges by utilizing AA5754H22 as a reference material and integrating a comprehensive experimental campaign with finite element numerical models and empirical material model developments. Our findings confirm that PFEPE facilitates a significant reduction in springback, achieving approximately a 100% reduction. Although the skin-effect introduces non-uniform current flux density distribution, its impact at the macroscopic level is negligible for the studied thin samples. While the numerical results of springback fails to accurately replicate experimental results, the developed material model aligns well with experimental trends.

在金属成形工业中，后成形电塑性效应(PFEPE)被认为是一种很有前途的技术，可以减轻成形力和解决回弹问题。然而，该技术的产业化仍存在一些研究空白。首先，缺乏关于应力减小对回弹影响的实验验证。其次，需要评估表面效应对当前减压指标的潜在影响。此外，一个后成形的电辅助弹塑性材料模型对于冲压工艺的进一步技术发展是必要的。本研究利用AA5754H22作为参考材料，并将综合实验活动与有限元数值模型和经验材料模型开发相结合，解决了这些挑战。我们的研究结果证实，PFEPE可以显著减少回弹，大约可以减少100%。虽然趋肤效应导致电流密度分布不均匀，但对于所研究的薄样品，其宏观影响可以忽略不计。虽然回弹的数值结果不能准确地复 制实验结果，但所建立的材料模型与实验趋势很好地吻合。

Tailorable Piezoelectric and Flexoelectric Output of a Polymer-Particle Composite

Ju Hwan (Jay) Shin, Min Zhou

doi:10.1016/j.mechmat.2024.105134

聚合物-颗粒复合材料的可定制压电和挠性电输出

Materials with different combinations of piezoelectric and flexoelectric properties offer multifunctionality and versatility in terms of modes of operation in sensing, actuation, and energy harvesting. We explore a microscopic mechanism for tailoring the macroscopic quasi-static mechanoelectrical output of polymer-particle composites by taking advantage of heterogeneity-induced enhancement of the stress fields and strain gradient fields. The idea focuses on using microscopic inclusions, such as embedded particles and voids, to manipulate the activation and relative contributions of the piezoelectric and flexoelectric effects under different modes of mechanical excitation, such as uniaxial compression and flexural bending. The material system studied is a composite of poly(vinylidene fluoride-co-trifluoroethylene [P(VDF-TrFE)] polymer and nanoaluminum (nAl) particles, or P(VDF-TrFE)/nAl. This system is interesting because P(VDF-TrFE) exhibits both piezoelectric and flexoelectric behaviors and nAl particles have significantly higher elastic stiffness than the polymer. A range of piezoelectric and flexoelectric properties of P(VDF-TrFE) and the stiffness of the particles are considered. Significant microstructural effects are found to enable tailoring of the mechanoelectrical response through microstructure variation. The responses of the composite are quantified using the effective piezoelectric constant () and the effective flexoelectric coefficient (). It is found that the effective macroscopic piezoelectric and flexoelectric behaviors can be changed either independently or simultaneously through different combinations of microstructure attribute changes. The mechanism revealed points out avenues for developing materials with tunable mechanoelectrical behaviors and multifunctionality.

具有不同压电和挠性组合的材料在传感、驱动和能量收集的操作模式方面提供了多功能和多功能性。我们探索了利用应力场和应变梯度场的非均质性增强来调整聚合物-颗粒复合材料宏观准静态机电输出的微观机制。该想法侧重于利用微观内含物，如嵌入颗粒和空隙，来操纵不同机械激励模式(如单轴压缩和弯曲弯曲)下压电和挠曲电效应的激活和相对贡献。所研究的材料体系是聚偏氟乙烯-共三氟乙烯[P(VDF-TrFE)]聚合物与纳米铝(nAl)颗粒的复合材料，或P(VDF-TrFE)/nAl。该体系很有趣，因为P(VDF-TrFE)同时表现出压电和柔电行为，nAl颗粒的弹性刚度明显高于聚合物。考虑了P(VDF-TrFE)的一系列压电和挠曲电性能以及颗粒的刚度。发现显著的微观结构效应可以通过微观结构变化来调整机电响应。利用有效压电常数()和有效挠曲电系数()对复合材料的响应进行量化。研究发现，通过不同的微观结构属性变化组合，可以单独或同时改变有效的宏观压电和挠电行为。揭示的机理为开发具有可调谐机电行为和多功能的材料指明了途径。

Dynamic rupture modeling in a complex fault zone with distributed and localized damage

Chunhui Zhao, Mid Shumon Mia, Ahmed Elbanna, Yehuda Ben-Zion

doi:10.1016/j.mechmat.2024.105139

具有分布和局部损伤的复杂断裂带的动态破裂模拟

Active fault zones have complex structural and geometric features that are expected to affect earthquake nucleation, rupture propagation with shear and volumetric deformation, and arrest. Earthquakes, in turn, dynamically activate co-seismic off-fault damage that may be both distributed and localized, affecting fault zone geometry and rheology, and further influencing post-seismic deformation and subsequent earthquake sequences. Understanding this co-evolution of fault zones and earthquakes is a fundamental challenge in computational rupture dynamics with consequential implications for earthquake physics, seismic hazard and risk. Here, we implement a continuum damage-breakage (CDB) rheology model in our MOOSE-FARMS dynamic rupture simulator to investigate the interplay between bulk damage and fault motion on the evolution of dynamic rupture, energy partitioning, and ground motion characteristics. We demonstrate several effects of damage (accounting for distributed cracking) and breakage (accounting for granulation) on rupture dynamics in the context of two prototype problems addressed currently in the 2D plane-strain setting: (1) a single planar fault and (2) a fracture network. We quantify the spatio-temporal reduction in wave speeds associated with dynamic ruptures in each of these cases and track the evolution of the original fault zone geometry. The results highlight the growth and coalescence of localization bands as well as competition between localized slip on the pre-existing faults vs. inelastic deformation in the bulk. We analyze the differences between off-fault dissipation through damage-breakage vs. plasticity and show that damage-induced softening increases the slip and slip rate, suggesting enhanced energy radiation and reduced energy dissipation. These results have important implications for long-standing problems in earthquake and fault physics as well as near-fault seismic hazard, and they motivate continuing towards 3D simulations and detailed near-fault observations to uncover the processes occurring in earthquake rupture zones.

活动断裂带具有复杂的结构和几何特征，预计会影响地震成核，剪切和体积变形的破裂传播以及阻止。地震反过来又动态地激活同震断层外破坏，这些破坏可能是分布的，也可能是局部的，影响断层带的几何形状和流变，并进一步影响震后变形和随后的地震序列。理解断层带和地震的这种共同演化是计算破裂动力学的一个基本挑战，对地震物理、地震危害和 风 险具有重要意义。在这里，我们在MOOSE-FARMS动态破裂模拟器中实现了连续损伤-破裂(CDB)流变模型，以研究大块损伤和断层运动之间对动态破裂演化、能量分配和地面运动特征的相互作用。我们在目前二维平面应变设置中解决的两个原型问题的背景下，展示了损伤(考虑分布式开裂)和断裂(考虑颗粒化)对破裂动力学的几种影响:(1)单个平面断层和(2)断裂网络。我们量化了每种情况下与动态破裂相关的波速时空减少，并跟踪了原始断裂带几何形状的演变。结果强调了局部化带的生长和合并，以及预先存在的断层上的局部滑动与体中的非弹性变形之间的竞争。我们分析了损伤-断裂和塑性引起的离断层耗散的差异，发现损伤引起的软化增加了滑移和滑移率，表明能量辐射增强，能量耗散减少。这些结果对地震和断层物理以及近断层地震危害的长期问题具有重要意义，并激励人们继续进行三维模拟和详细的近断层观测，以揭示地震断裂带中发生的过程。

International Journal of Plasticity

Atomic-resolution investigations on dislocation-assisted evolution of {101¯3} twin boundaries in a magnesium alloy

Huhu Su, Qun Zu, Zhiqing Yang, Hengqiang Ye

doi:10.1016/j.ijplas.2024.104108

镁合金中{101¯3}孪生边界位错辅助演化的原子分辨率研究

{101¯3}〈303¯2¯〉 twinning is usually activated at the later stage of plastic deformation of Mg alloys, which is closely relevant to their fracture behavior. Reactions between slip dislocations and twin boundaries (TBs) are suggested to facilitate TB migration, retarding the premature TB cracking. Here, dislocation-assisted evolution of {101¯3} TBs in a Mg alloy subjected to cyclic deformation were studied and modeled, according to transmission electron microscopy observations, theoretical analyses of interfacial defects, and molecular dynamics simulations. Atomic-resolution experimental observations showed that symmetric tilt grain boundaries (STGBs) near the {101¯3} twin orientation with steps were generated in the deformed Mg alloy. Theoretical analyses and atomistic simulations indicated that transformation of {101¯3} TBs into the STGBs could occur by reactions with incident basal〈a60〉dislocations in pairs from the twin and matrix respectively under the normal stress. STGB steps would be produced by reactions of individual basal 〈a60〉dislocations with GB dislocations at the STGB. Importantly, resultant steps could further emit {101¯3} twinning dislocations to facilitate the STGB migration. Moreover, STGBs near the {101¯3} twin orientation could evolve back into {101¯3} TBs either by reactions with an array of basal〈a60〉dislocations, or by a GB sliding of b =〈303¯2¯〉theoretically. Our results may provide insights into the mechanisms of {101¯3} TB evolution in Mg alloys, which plays important roles in their plastic deformation and plasticity.

{101¯3}〈303¯2¯〉孪晶通常在镁合金塑性变形的后期被激活，这与其断裂行为密切相关。滑移位错和孪晶边界（TBs）之间的反应被认为能促进 TB 迁移，延缓 TB 过早开裂。在这里，位错辅助{101¯3}孪晶的演化是在镁合金中进行的。在此，根据透射电子显微镜观察、界面缺陷理论分析和分子动力学模拟，研究了循环变形下镁合金中{101¯3}位错辅助孪晶的演化并建立了模型。原子分辨率实验观察结果表明，在变形镁合金中产生了靠近{101¯3}孪晶取向的对称倾斜晶界（STGB）。理论分析和原子模拟表明，{101¯3} TBs 转变为 STGBs 在法向应力作用下，孪晶和基体分别与成对的基底〈a60〉位点发生反应，从而使{101¯3}孪晶转变为STGB。在STGB处，单个基底〈a60〉位错与GB位错发生反应，从而产生STGB台阶。重要的是，由此产生的阶梯会进一步释放出{101¯3}孪生位错，从而促进STGB的迁移。此外，靠近{101¯3}孪晶取向的 STGB 可能会演化回{101¯3｝ TB，或者通过与基底〈a60〉位错阵列的反应，或者通过b =〈303¯2¯〉理论上的GB滑动。我们的研究结果可以帮助我们深入了解镁合金中{101¯3｝ 在镁合金的塑性变形和塑性中起重要作用。

Thin-Walled Structures

Probabilistic resistance predictions of laterally restrained cellular steel beams by natural gradient boosting

Vitaliy V. Degtyarev, Stephen J. Hicks, Felipe Piana Vendramell Ferreira, Konstantinos Daniel Tsavdaridis

doi:10.1016/j.tws.2024.112367

用自然梯度助推法预测横向约束胞状钢梁抗力的概率

Accurate and reliable cellular steel beam resistance predictions are essential for economical and safe designs of steel-framed buildings with such beams. This paper proposes a new machine-learning (ML) model based on the natural gradient boosting (NGBoost) algorithm to predict probabilistic load-bearing capacities of laterally restrained cellular beams subjected to uniformly distributed loads, considering all possible failure modes and their interactions. The NGBoost model was developed based on a database with 14,094 numerical simulation results and interpreted using the SHapley Additive exPlanations (SHAP) method commonly used for ML model explanation and interpretation. The resistance reduction factors required for the NGBoost model to meet the reliability requirements of the European and US design frameworks were determined via reliability analyses using the methods given in the respective standards and the improved Hasofer-Lind-Rackwitz–Fiessler (iHL-RF) method. Comparisons of the developed NGBoost model with other ML models and existing design provisions indicate that the former is as accurate as other ML models (while offering probabilistic predictions) and significantly outperforms the existing design provisions. A web application was developed and deployed online to predict the ultimate uniform loads of laterally restrained cellular beams with the developed NGBoost model. The proposed NGBoost model can facilitate preliminary cellular steel beam designs and investigating parameters affecting their resistance.

准确、可靠的蜂窝钢梁抗力预测对采用蜂窝钢梁的钢结构建筑的经济、安全设计至关重要。本文提出了一种基于自然梯度增强(NGBoost)算法的机器学习(ML)模型，用于在考虑所有可能的失效模式及其相互作用的情况下，预测受均匀分布载荷作用下横向约束蜂窝梁的概率承载能力。NGBoost模型是基于一个包含14094个数值模拟结果的数据库开发的，并使用ML模型解释和解释常用的SHapley加性解释(SHAP)方法进行解释。采用各自标准中给出的方法和改进的hasfer - lind - rackwitz - fiessler (iHL-RF)方法进行可靠性分析，确定了NGBoost模型满足欧美设计框架可靠性要求所需的阻力减小因子。将开发的NGBoost模型与其他机器学习模型和现有设计条款进行比较，表明前者与其他机器学习模型一样准确(同时提供概率预测)，并且显著优于现有设计条款。开发并在线部署了一个web应用程序，利用开发的NGBoost模型预测横向约束蜂窝梁的最终均匀载荷。所提出的NGBoost模型可以促进蜂窝钢梁的初步设计和研究影响其阻力的参数。

A semi-analytical method for determining the mode-I delamination R-curve and fiber bridging traction-separation law of Double-double laminates

Menglin Zhao, Siyuan Wang, Zehong Liu, Zhengping Chang, Zhongqi Wang, Yonggang Kang

doi:10.1016/j.tws.2024.112383

一种确定双-双层合板i型分层r曲线和纤维桥接牵拉-分离规律的半解析方法

Delamination, as one of the most prevalent failure modes of composites, was significantly influenced by the interface angles. In contrast to the limited combinations of interface angles found in traditional laminates, DD laminates, with unique sequence [±Φ/±Ψ]rT and diverse interface angles , urgently required extensive experiments and high-precision simulation analyses to delve into the complexities and unique properties of their interlayer performance. However, the calculation process of current method for determining the R-curve and the bridging traction-separation law was time-consuming. This study proposed a simplified semi-analytical method based on the Euler–Bernoulli beam theory that only required recording initial crack length, final crack length, initial compliance and final compliance. The method validation showed that the deviation between the results obtained from the semi-analytical method and the MBT method averaged no more than 2%. In addition, a tri-linear cohesive zone model based on the delamination fracture micro-mechanism was developed combining semi-analytical method. Both the initial load and ultimate load errors between the simulation and experimental results were within 5N, showing the accuracy of the model and the semi-analytical method. This method provided a simple and effective way to study the delamination propagation behaviors of DD laminates.

分层是复合材料最常见的失效模式之一，受界面角的影响很大。与传统层压板有限的界面角组合不同，DD 层压板具有独特的 [±Φ/±Ψ]rT 序列和多样化的界面角，迫切需要大量实验和高精度模拟分析来深入研究其层间性能的复杂性和独特性。然而，现有方法确定 R 曲线和桥接牵引分离定律的计算过程非常耗时。本研究提出了一种基于欧拉-伯努利梁理论的简化半分析方法，只需记录初始裂缝长度、最终裂缝长度、初始顺应性和最终顺应性。方法验证表明，半分析方法和 MBT 方法得出的结果平均偏差不超过 2%。此外，结合半分析方法，还建立了基于分层断裂微观机制的三线性内聚区模型。模拟结果与实验结果之间的初始载荷和极限载荷误差均在 5N 以内，表明了模型和半解析方法的准确性。该方法为研究 DD 层压板的分层扩展行为提供了一种简单有效的方法。

Low-cycle fatigue behaviour of concrete-filled double skin steel tubular (CFDST) members for wind turbine towers

Jia-Hao Fan, Wen-Da Wang, Yan-Li Shi, Long Zheng

doi:10.1016/j.tws.2024.112384

 风电塔架双皮钢管混凝土构件的低周疲劳性能

Wind energy has the advantages of being clean and renewable. Wind turbine towers endure horizontal cyclic loads that could influence the performance of entire structure. To clarify the low-cycle fatigue behaviour of concrete-filled double skin steel tubular (CFDST) members, a total of 16 specimens were experimented. The hollow, slenderness, and axial compression ratios are specifically designed to clarify the effects on performance under constant amplitude loading and hysteretic loading conditions. The typical failure modes under both loading conditions and the relationship between loop strain, loop bearing capacity, loop energy dissipation, cycle number, and various degradation indices were analysed. Studies indicate that the failure mode under low-cycle fatigue loading is mainly local deformation, which includes transverse fracture occurring at the region between the steel tube and ribbed stiffener, the crushing concrete. Fatigue specimens with different amplitudes exhibit varying shapes of hysteresis responses. Higher amplitudes could enhance damage and significantly reduce fatigue life. Increasing the hollow and axial compression ratios boosts the energy dissipation capacity, and decreasing the slenderness ratio enhances the lateral resistance. A 2% constant amplitude preload intensifies the degradation of bearing capacity and energy dissipation under subsequent constant amplitude loading.

风能具有清洁和可再生的优点。风力发电塔承受的水平循环荷载会影响整个结构的性能。为明确双皮钢管混凝土构件的低周疲劳性能，对16个试件进行了试验研究。中空、长细比和轴压比是专门设计来阐明在恒幅加载和滞后加载条件下对性能的影响。分析了两种加载条件下的典型破坏模式以及环应变、环承载力、环能量耗散、环数与各退化指标之间的关系。研究表明，低周疲劳荷载作用下钢管的破坏模式主要为局部变形，包括钢管与加肋加劲肋之间的区域发生横向断裂、混凝土破碎。不同幅值的疲劳试样表现出不同形状的迟滞响应。较高的振幅可以增强损伤，显著降低疲劳寿命。增大空心压缩比和轴压比可提高耗能能力，减小长细比可提高侧阻能力。2%恒幅预加载加剧了后续恒幅加载下的承载力退化和能量耗散。

Engineering static non-reciprocity in mechanical metamaterials

Jinliang Wang, Qingxiang Ji, Muamer Kadic, Changguo Wang

doi:10.1016/j.tws.2024.112373

机械超材料的工程静态非互易性

Non-reciprocity has recently been achieved in static fields by mechanical metamaterial that combines large non-linearity and asymmetric geometry. Novel devices are then designed to obtain one-way mechanical functionalities. Non-linearity is the fundamental part that regulates static non-reciprocity, but the influential path remains difficult to quantify. In this work, we employ the geometrically exact beam model to obtain the nonlinear deformation profile of mechanical metamaterials, and build nonlinear equations that govern the deformation behavior. A new two-step method is proposed to solve the nonlinear governing equations, which avoids Jacobi matrix singularity. We establish an accurate model that predicts the non-reciprocal mechanical behavior and verify its accuracy by finite element method. To gain further insight into non-linearity’s influences on mechanical non-reciprocity, we investigate mechanical metamaterials with curved beams, explore the effects of initial curvature on non-reciprocity, and engineer their non-reciprocity to obtain different non-reciprocal force–displacement responses. Our work offers beneficial vehicles to realize static direction-selective functionalities, contributing to shock absorption, vibration damping, and mechanical energy manipulation.

近年来，结合了大非线性和非对称几何结构的机械超材料在静态场中实现了非互易性。然后设计新颖的装置以获得单向机械功能。非线性是调节静态非互易的基本部分，但其影响路径难以量化。在这项工作中，我们采用几何精确的梁模型来获得机械超材料的非线性变形轮廓，并建立了控制变形行为的非线性方程。提出了一种新的两步法求解非线性控制方程，避免了雅可比矩阵的奇异性。建立了预测非互易力学行为的精确模型，并用有限元法验证了模型的准确性。为了进一步了解非线性对力学非互易的影响，我们研究了具有弯曲梁的力学超材料，探讨了初始曲率对非互易的影响，并对其非互易进行了工程设计，以获得不同的非互易力-位移响应。我们的工作为实现静态方向选择功能提供了有益的载体，有助于减震、减振和机械能操纵。

Flexural behaviour of Q1100 ultra high strength steel welded I-sections

Fei Yin, Lu Yang, Jie Wang, Lei Zhu

doi:10.1016/j.tws.2024.112390

Q1100超高强度钢焊接工字钢的弯曲性能

An experimental and numerical program investigating the in-plane flexural behaviour of Q1100 ultra high strength steel (UHSS) welded I-sections is presented in the current paper. The testing program comprised of material coupon tests, measurements of residual stresses, and in-plane 3-point bending tests. Subsequently, a numerical program was executed, involving the development of finite element (FE) models. The FE models validated against the experiments were subsequently employed for parametric studies, aiming at assessing the flexural behaviour of Q1100 welded I-sections across a broader spectrum of section geometries. The data obtained from the experiments and numerical simulations were used to assess the applicability of prevailing design provisions outlined in the European, Chinese and Australian codes for high-strength steel structures. These design provisions encompass classification limits for cross-sections and predicted methods for cross-sectional resistance in bending. Via reliability analyses, adjustments were made to the cross-section classification limits. Finally, a modified direct strength method was proposed to predict the in-plane bending resistance for Q1100 welded I-sections.

本文提出了Q1100超高强度钢(UHSS)工字钢焊接断面面内弯曲性能的实验和数值计算程序。测试程序包括材料粘片测试、残余应力测量和平面内三点弯曲测试。随后，执行了一个数值程序，包括有限元模型的开发。根据实验验证的有限元模型随后被用于参数化研究，旨在评估Q1100焊接i型截面在更广泛的截面几何形状范围内的弯曲行为。从实验和数值模拟中获得的数据用于评估欧洲、中国和澳大利亚高强度钢结构规范中现行设计规定的适用性。这些设计规定包括截面的分类限制和弯曲截面阻力的预测方法。通过信度分析，对截面分类限值进行了调整。最后，提出了一种改进的直接强度法来预测Q1100焊接工字钢的面内弯曲抗力。

Bifurcation boundaries analysis of the thin-walled internal resonance energy harvester

Tao Lin, Lingzhi Wang, Ming Yang, Zhitao Yan, Xiaochun Nie

doi:10.1016/j.tws.2024.112372

薄壁内共振能量采集器的分岔边界分析

The dynamic instability of the thin-walled 1: 2 internal resonant piezoelectric vibration energy harvester is investigated. Previously work (Nie et al., 2019) derived the nonlinear electromechanical-coupled governing equations and validated them experimentally. The modulation equations are performed by the method of multiple scales. The system stability is obtained from the eigenvalues of the Jacobi matrix. Then, three types of bifurcation boundaries of the system are determined analytically and simulated numerically via Routh–Hurwitz criterion. Results show that internal resonance complicates the dynamic properties of the bifurcation region. For a large external excitation, new saddle node bifurcation regions appear in the stability diagram. Moreover, the new saddle node and Hopf bifurcation regions may intertwine. Furthermore, as the acceleration excitation increases, the system can be observed to transition to stable-unstable-stable states. The system’s high and low branch responses are fed back by the system’s large and small initial conditions. The system’s periodic and quasi-periodic motions are characterized by time response, FFT, phase trajectory, and Poincaré map. The study of the stability boundary of the piezoelectric energy harvester contributes to the harvesting of energy from ambient vibrations over a broader frequency range.

研究了薄壁1:2内谐振压电振动能量采集器的动力失稳特性。之前的工作(Nie et al.， 2019)推导了非线性机电耦合控制方程，并通过实验验证了它们。用多尺度法求解了调制方程。由雅可比矩阵的特征值得到系统的稳定性。然后，利用Routh-Hurwitz准则对系统的三种分岔边界进行了解析确定和数值模拟。结果表明，内部共振使分岔区的动态特性复杂化。当外部激励较大时，稳定性图中出现新的鞍节点分岔区。此外，新的鞍节点和Hopf分岔区域可能会交织在一起。此外，随着加速度激励的增加，可以观察到系统过渡到稳定-不稳定-稳定状态。系统的高、低支路响应由系统的大、小初始条件反馈。系统的周期和准周期运动由时间响应、FFT、相位轨迹和poincarcarcarr映射表征。压电能量采集器稳定边界的研究有助于在更宽的频率范围内从环境振动中收集能量。