今日更新：International Journal of Solids and Structures 1 篇，Journal of the Mechanics and Physics of Solids 5 篇，Mechanics of Materials 1 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 17 篇International Journal of Solids and StructuresFinite element analysis of crack propagation, crack-gap-filling, and recovery behaviors of mechanical properties in oxidation-induced self-healing ceramicsMostafizur Rahman, Taiyo Maeda, Toshio Osada, Shingo Ozakidoi:10.1016/j.ijsolstr.2024.113104氧化自愈陶瓷裂纹扩展、裂纹间隙填充及力学性能恢复行为的有限元分析The oxidation-induced self-healing of cracks is an attractive function for the application of ceramics in high-temperature structural components requiring high reliability. To further optimize materials or components for practical applications, the development of numerical simulation techniques is of importance. In this study, we examined crack growth, crack-gap-filling by oxide, and re-cracking behaviors in chevron-notched specimens under various load and temperature conditions by adopting a finite element analysis (FEA) approach incorporating a damage-healing constitutive model based on fracture mechanics and oxidation kinetics. Furthermore, by implementing the mechanical properties and oxidation kinetic parameters of reported self-healing ceramics composites into the FEA, we examined the effects of the composition and composite structure on the cracking and healing behaviors. Crack-gap-filling simulations suggested that the damage variables gradually decreased from the crack tip, and the minimum healing time was determined by the time required for the complete filling of the element at the crack mouth with the largest crack opening width. Furthermore, the recovery of the stiffness and strength could be successfully reproduced after complete healing with a reasonable healing temperature and time. The proposed FEA approach could also contribute to estimating the minimum healing time required at various temperatures to heal a given damage for various composites氧化诱导的裂纹自愈功能是陶瓷在高温高可靠性结构件中的应用。为了进一步优化材料或部件的实际应用，数值模拟技术的发展是非常重要的。在这项研究中，我们采用基于断裂力学和氧化动力学的损伤-愈合本构模型的有限元分析（FEA）方法，研究了在不同载荷和温度条件下，锯齿形缺口试样的裂纹扩展、裂纹间隙被氧化物填充和再开裂行为。此外，通过对已报道的自愈陶瓷复合材料的力学性能和氧化动力学参数进行有限元分析，研究了成分和复合材料结构对其开裂和自愈行为的影响。裂隙充填模拟结果表明，损伤变量从裂隙尖端开始逐渐减小，最小愈合时间由裂隙张开宽度最大的裂隙口处单元完全充填所需时间决定。此外，在合理的修复温度和时间下，完全修复后的刚度和强度可以成功地恢复。所提出的有限元分析方法也有助于估计各种复合材料在不同温度下修复给定损伤所需的最小愈合时间Journal of the Mechanics and Physics of SolidsWrinkling of differentially growing bilayers with similar film and substrate moduliJiajia Shen, Yibin Fu, Alberto Pirrera, Rainer M.J. Grohdoi:10.1016/j.jmps.2024.105900 具有相似薄膜和衬底模量的不同生长双层的起皱Growth-induced surface wrinkling in constrained bilayers comprising a thin film attached to a thick substrate is a canonical model for understanding pattern formation in many biological systems. While the bilayer model has received much prior attention, the nonlinear behaviour for arrangements with similar film and substrate properties, or substrate growth that outpaces film growth, remains poorly understood. This paper therefore focuses on these cases in which the substrate’s elasticity dominates surface wrinkling. By combining analytical modelling and finite element simulations incorporating advanced path-following techniques, we characterise critical wrinkling states and explore the initial and advanced post-buckling behaviour for a wide range of film-to-substrate modulus and growth rate ratios. It is shown that the classical leading-order asymptotic expression for the critical strain is not of sufficient accuracy for film-to-substrate modulus ratios below 50, and higher order correction terms are presented. Leveraging a weakly nonlinear analytical model, we introduce a phase diagram categorising stable and unstable post-buckling regimes. Advanced path-following simulations are employed to unveil the evolution of wrinkling patterns, from initial sinusoidal instabilities to complex formations involving period doubling, quadrupling, and eventual surface creasing. These comprehensive phase diagrams, parameterised by film-to-substrate modulus and growth rate ratios, provide new insights into the rich dynamics of surface wrinkling. Finally, we demonstrate the existence of multi-stability in the advanced post-buckling regimes for bilayers experiencing substrate-dominated growth. This work contributes to the understanding of the mechanics underlying pattern formation in growing bilayers over the entire parameter regime, with potential implications for explaining biological morphogenesis and informing the development of novel diagnostic tools and artificial flexible electronic skins.在由附着在厚衬底上的薄膜组成的受约束双层中，生长诱导的表面起皱是理解许多生物系统中图案形成的典型模型。虽然双层模型受到了广泛的关注，但对于具有相似薄膜和衬底性质的排列，或衬底生长超过薄膜生长的非线性行为，人们仍然知之甚少。因此，本文的重点是在这些情况下，衬底的弹性主导表面起皱。通过将分析建模和结合先进路径跟踪技术的有限元模拟相结合，我们描述了关键的起皱状态，并探索了大范围薄膜-衬底模量和生长速率比的初始和高级后屈曲行为。结果表明，当薄膜与衬底模量比小于50时，临界应变的经典首阶渐近表达式精度不足，并给出了高阶修正项。利用弱非线性分析模型，我们引入了一个相图分类稳定和不稳定的后屈曲状态。采用先进的路径跟踪模拟来揭示起皱模式的演变，从最初的正弦不稳定到复杂的地层，包括周期翻倍、四倍和最终的表面折痕。这些全面的相图，由薄膜-衬底模量和生长速率比参数化，为表面起皱的丰富动力学提供了新的见解。最后，我们证明了在经历衬底主导生长的双分子层的高级后屈曲状态下存在多重稳定性。这项工作有助于理解在整个参数范围内生长的双层中模式形成的机制，具有解释生物形态发生的潜在意义，并为新型诊断工具和人工柔性电子皮肤的开发提供信息。Filled elastomers sliding over smooth obstacles: Experiments and modeling in large deformationsM. de Lorenzo, P. Le Tallec, O. Lopez-Pamies, P. Bussettadoi:10.1016/j.jmps.2024.105899在光滑障碍物上滑动的填充弹性体：大变形的实验和建模The objective of this paper is to shed light on the mechanical response of filled elastomers in sliding contact. Compared to situations encountered by tires in breaking conditions, the study only considers smooth obstacles in order to analyse the contribution of finite deformations and of the complex viscosity of filled elastomers without facing all the complexity of surface roughness. For this purpose, a new experiment is introduced that allows to measure the friction on the surface of a filled elastomer that is subjected to large local deformation through a cyclic contact loading applied by sliding indenters. The setup uses smooth spherical indenters sliding on the material of interest within a temperature controlled water tank. The relevance of adhesion forces is reduced by using Teflon as a dry lubricant and Sinnozon as a surfactant. To analyze the experimental results, full-field simulations of the experiments are carried out within the setting of finite viscoelastodynamics by making use of two types of viscoelastic constitutive models for the filled elastomer: (i) a classical viscoelastic model combining a Mooney–Rivlin equilibrium elasticity and Maxwell branches with constant viscosities and (ii) an internal-variable-based viscoelastic model that was introduced in (Kumar and Lopez-Pamies, Comptes Rendus Mecanique 344, 102-112) for unfilled elastomers and that is extended herein to account for the more complex viscous response of filled elastomers.本文旨在阐明填充弹性体在滑动接触中的机械响应。与轮胎在制动条件下遇到的情况相比，本研究仅考虑光滑障碍物，以分析填充弹性体的有限变形和复杂黏度的贡献，而不需要面对表面粗糙度的所有复杂性。为此，引入了一种新的实验方法，可以测量在由滑动压头施加的循环接触载荷下受到大范围局部变形的填充弹性体表面的摩擦力。该实验在温度控制的水槽中进行，使用光滑的球形压头在感兴趣的材料上滑动。通过使用特氟龙作为干润滑剂和辛诺赞作为表面活性剂，可以减少粘附力的影响。为了分析实验结果，在有限黏弹性动力学的框架下，对实验进行了全域模拟，并使用了两种类型的填充弹性体黏弹性本构模型。(i) 一种经典的黏弹性模型，结合了莫尼-里夫林（Mooney-Rivlin）平衡弹性和具有恒定黏度的马克斯韦尔（Maxwell）分支；(ii) 一种基于内部变量的黏弹性模型，在Kumar和Lopez-Pamies的论文《Comptes Rendus Mecanique 344, 102-112》中被引入，用于描述未填充弹性体的黏弹性行为，并在本文中被扩展以考虑填充弹性体更为复杂的黏性响应。Tuning the stiffness and stretchability of micro-scale-structured polymer membrane simultaneously by integrating mechanical modeling and spatiotemporal controllable photolithographHuibin Shi, Ziming Yan, Jiaxin Shi, Zhuoran Yang, Yue Gao, Jun Xu, Zhanli Liudoi:10.1016/j.jmps.2024.105906结合力学建模和时空可控光刻技术，对微尺度结构聚合物膜的刚度和拉伸性进行同步调整Micro-scale structural polymer membranes with desired mechanical properties, such as modulus and stretchability, have extensive applications in repair scaffolds, stretchable electronic devices, etc., yet how to achieve the simultaneous tunability of high modulus (MPa-level) and excellent resilience in micron-scale polymer membrane remains challenge. In this work, based on the material-structure integrated design aided by mechanical modeling and photolithograph, a micro-scale-structured solid-state lithography polyurethane-urea (UVSLPU) membrane has been fabricated, achieving a wide range of controllability on elastic modulus of 25-55 MPa and stretchability of 2.7-7.6 by simultaneously controlling the exposure time and area. Based on the physical mechanism of solid-state lithography, a novel visco-hyperelastic constitutive model is developed to facilitate the quantitative tunning of the mechanical property of UVSLPU. According to the microstructure analysis, the model decomposes the free energy of UVSLPU into three components, including crosslinked network, free chains as well as dangling chains, and describes the influence of exposure time on their nonlinear evolutions through increasing chain density and reducing the number of Kuhn monomers per chain. The proposed model is validated through uniaxial tensile tests conducted at different strain rates and exposure conditions, and reveals the significant contribution of crosslinks and free chains in enhancing the modulus over exposure time. Then, by integrating constitutive modeling and spatiotemporal controllable photolithograph, the design and manufacture for the micro-scale-structured UVSLPU membrane achieving increasing stiffness without losing the stretchability is realized by precisely controlling the exposure area. This work offers a novel and efficient approach for the design and manufacture of micro-scale-structured membranes with desired mechanical properties.微尺度结构聚合物膜具有理想的力学性能，如模量和可拉伸性，在修复支架、可拉伸电子器件等方面有着广泛的应用，但如何在微米尺度聚合物膜中同时实现高模量（mpa级）和优异的弹性可调性仍然是一个挑战。本研究以材料-结构一体化设计为基础，借助机械建模和光刻技术，制备了微尺度结构固态光刻聚氨酯-尿素（UVSLPU）膜，通过同时控制曝光时间和曝光面积，实现了弹性模量25- 55mpa的大范围可控性和拉伸性2.7-7.6的大范围可控性。基于固态光刻的物理机理，建立了一种新的粘-超弹性本构模型，便于对UVSLPU的力学性能进行定量调整。根据微观结构分析，该模型将UVSLPU的自由能分解为交联网络、自由链和悬垂链三组分，并描述了暴露时间通过增加链密度和减少每链库恩单体数对其非线性演化的影响。通过在不同应变速率和暴露条件下进行的单轴拉伸试验验证了所提出的模型，并揭示了交联和自由链在提高模量随暴露时间的显著贡献。然后，将本构建模与时空可控光刻技术相结合，通过对曝光面积的精确控制，实现了微尺度结构UVSLPU膜的设计与制造，实现了在增加膜刚度的同时又不失拉伸性。这项工作为设计和制造具有理想力学性能的微尺度结构膜提供了一种新颖而有效的方法。Unifying creep and fatigue modeling of composites: A time-homogenized micromechanical framework with viscoplasticity and cohesive damageD. Kovačević, P. Hofman, I.B.C.M. Rocha, F.P. van der Meerdoi:10.1016/j.jmps.2024.105904复合材料蠕变和疲劳模型的统一：具有粘塑性和内聚损伤的时间均质微力学框架A micromechanical model for simulating failure of unidirectional composites under cyclic loading has been developed and tested. To efficiently pass through the loading signal, a two-scale temporal framework with adaptive stepping is proposed, with a varying step size between macro time steps, and a fixed number of equally spaced micro time steps in between. With the focus on matrix dominated failure under off-axis loading, viscoplasticity and microcracking are included in the model for the polymer matrix, while carbon fibers are modeled as elastic. For a proper representation of viscous deformation in the matrix under cyclic loading, a two-scale version of the Eindhoven Glassy Polymer constitutive model is formulated, that is based on time homogenization with an effective time increment. The failure state of the representative volume element is reached by the initiation and damaging of cohesive microcracks. Cyclic and static degradation are represented by using Dávila’s fatigue damage function, which is built on top of Turon’s quasi-static cohesive model. The model results are compared with available experimental data on unidirectional carbon/PEEK composites tested at different stress levels, load ratios, frequencies and off-axis angles. Plasticity controlled and crack growth controlled failure mechanisms, characteristic of the long-term response of polymeric composites, are captured by the model, as well as their distinct frequency dependence. As a limit case, the model is able to reproduce the time to failure in creep loading, where the heterogeneous microstructure and viscoplastic flow of the matrix trigger the evolution of quasi-static damage. However, for the studied material system, the present model does not accurately reproduce the load ratio dependence and the off-axis angle dependence of the crack growth controlled failure mechanism.建立了模拟单向复合材料在循环载荷作用下破坏的细观力学模型并进行了试验。为了有效地通过加载信号，提出了一种具有自适应步进的双尺度时间框架，该框架在宏时间步长之间具有不同的步长，在宏时间步长之间具有固定数量等间隔的微时间步长。基于离轴载荷作用下基体的主导破坏，将粘塑性和微裂纹纳入聚合物基体模型，而碳纤维模型采用弹性模型。为了更好地表达循环载荷下基体中的粘性变形，本文建立了基于有效时间增量的时间均匀化的双尺度埃因霍温玻璃聚合物本构模型。典型体积元的破坏状态是由内聚微裂纹的萌生和破坏引起的。使用Dávila疲劳损伤函数表示循环和静态退化，该函数建立在Turon的准静态内聚模型之上。将模型结果与现有的单向碳/PEEK复合材料在不同应力水平、载荷比、频率和离轴角下的实验数据进行了比较。塑性控制和裂纹扩展控制的破坏机制是聚合物复合材料长期响应的特征，该模型捕获了它们独特的频率依赖性。在极限情况下，该模型能够再现蠕变加载下的破坏时间，在蠕变加载下，基体的非均质微观结构和粘塑性流动触发了准静态损伤的演化。然而，对于所研究的材料体系，该模型不能准确再现裂纹扩展控制破坏机制的载荷比依赖关系和离轴角依赖关系。Eulerian rates of elastic incompatibilities applied to size-dependent hardening in finite torsionM.B. Rubin, Lorenzo Bardelladoi:10.1016/j.jmps.2024.105905欧拉弹性不相容率在有限扭转尺寸相关硬化中的应用Measures of rates of elastic incompatibilities are developed within an Eulerian framework for finite-deformation response of anisotropic elastic-inelastic materials. Such framework relies on the evolution of microstructural vectors. It is emphasized that the rates of incompatibilities, here denoted as R i j , depend on the constitutive equation for the rate of inelasticity. For small strains and rotations, R i j are equal to the negative of the components of the rate of Nye-Kröner’s dislocation density tensor. In contrast to these small strain components, each R i j is invariant under superposed rigid body motions such that it can be used independently in the constitutive equations to describe the material behavior. Specifically, in this work, R i j provide a size-dependent enhancement to hardening that can increase or decrease during loading history, modeling the generation and annihilation of densities of geometrically necessary dislocations in metal plasticity. The application to the finite-deformation torsion of thin wires demonstrates the potential of this approach and the importance of the constitutive equation for the plastic spin rate both on the rotations of the microstructural vectors and on the predicted size-effect.在各向异性弹性-非弹性材料有限变形响应的欧拉框架内，提出了弹性不相容率的度量方法。这种框架依赖于微观结构载体的演化。要强调的是，不相容率，这里表示为R i j，取决于本构方程的非弹性率。对于小应变和旋转，R i j等于Nye-Kröner位错密度张量速率分量的负值。与这些小的应变分量相反，每个R i j在叠加刚体运动下是不变的，因此它可以独立地用于本构方程来描述材料的行为。具体来说，在这项工作中，R i j提供了一种尺寸相关的硬化增强，可以在加载过程中增加或减少，模拟了金属塑性中几何必要位错密度的产生和湮灭。细丝有限变形扭转的应用表明了该方法的潜力，以及塑性自旋速率本构方程对微观组织矢量旋转和预测尺寸效应的重要性。Mechanics of MaterialsDamage Quantification in Concrete under Uniaxial Compression Using Microcomputed Tomography and Digital Volume Correlation with Consideration of HeterogeneityShangyu Yang, Haizhou Liu, Lingtao Mao, Fangao Li, Bingjie Wei, Yang Ju, François Hilddoi:10.1016/j.mechmat.2024.105178考虑非均质性的微计算机断层扫描和数字体积相关对混凝土单轴压缩损伤的量化Finite element-based digital volume correlation with mechanical regularization was utilized to measure the deformation fields in a concrete specimen under uniaxial compression based on in-situ (via microcomputed tomography) experiment. Heterogeneous and damage settings were introduced in the mechanical regularization. The mechanical response of the matrix and aggregates was investigated. The three-dimensional morphology of subvoxel microcrack openings was measured, the overall assessment and local depiction of concrete damage were quantified. Subvoxel microcrack openings greater than 0.26 vx were identified. The average maximum principal and average volumetric strains in the matrix were higher than those in the aggregates, and noticeable strain concentrations existed in the interfacial transition zone and pore edges. Microcracks initiated in the macroscopic elastic stage, whereas voxel-level crack openings were observed at 90% of the ultimate load. This study provides experimental support for further revealing the growth process of concrete damage.基于原位（微计算机断层扫描）实验，采用基于有限元的数字体积相关与力学正则化方法对混凝土试件单轴压缩变形场进行了测量。在力学正则化中引入了非均匀和损伤设置。研究了基质和骨料的力学响应。测量了亚体素微裂缝开口的三维形态，量化了混凝土损伤的整体评估和局部描述。亚体素微裂纹开口大于0.26 vx。基质的平均最大主应变和平均体积应变均高于团聚体，且界面过渡区和孔隙边缘存在明显的应变集中。微裂纹起源于宏观弹性阶段，而体素级裂纹在极限荷载的90%时出现。本研究为进一步揭示混凝土损伤的发展过程提供了实验支持。International Journal of Plasticity3D strain heterogeneity and fracture studied by X-ray tomography and crystal plasticity in an aluminium alloyMaryse Gille, Henry Proudhon, Jette Oddershede, Romain Quey, Thilo F. Morgeneyerdoi:10.1016/j.ijplas.2024.104146 用x射线断层成像和晶体塑性研究铝合金的三维应变非均质性和断口Strong correlations between measured strain fields and crystal plasticity finite element (CP-FE) predictions based on the real microstructure are found for a plane strain tensile specimen made of 6016 T4 aluminium alloy. This is achieved using multimodal X-ray lab tomography giving access to both the initial grain structure and the strain evolution. The real microstructure of the central region of interest (ROI) of the undeformed specimen is obtained non destructively using lab-based diffraction contrast tomography (DCT) and meshing. An in situ tensile test, using absorption contrast tomography (ACT) is then performed for twelve loading increments up to fracture. Taking advantage of the plane strain condition, the evolution of the internal strain field is measured by two-dimensional digital image correlation (DIC) in the material bulk using the natural speckle provided by intermetallic particles. Early strain heterogeneities in the form of slanted bands, that are spatially stable over time, are revealed and the fracture path – determined from the post mortem scan – is found to coincide with the bands exhibiting maximum strain. CP-FE simulations are performed on the meshed microstructure of the specimen acquired by DCT and are compared with image correlation measurements. The measured strain fields are well described by 3D CP-FE predictions, whilst it is shown that neither a macroscopic anisotropic plasticity model nor a CP-FE simulation with random grain orientations could reproduce the measurements.发现6016 T4铝合金平面应变拉伸试样的应变场测量值与基于真实微观结构的晶体塑性有限元（CP-FE）预测值之间存在较强的相关性。这是通过使用多模态x射线实验室断层扫描实现的，可以获得初始晶粒结构和应变演变。利用基于实验室的衍射对比层析成像（DCT）和网格划分，获得了未变形试样中心感兴趣区域（ROI）的真实微观结构。然后使用吸收对比断层扫描（ACT）进行原位拉伸试验，进行12次加载增量直至断裂。利用平面应变条件，利用金属间颗粒提供的自然散斑，利用二维数字图像相关（DIC）技术测量了材料体内部应变场的演化。早期的应变不均匀以倾斜带的形式出现，随着时间的推移在空间上是稳定的，并且从尸检扫描中确定的断裂路径与显示最大应变的带一致。对DCT采集的试样的网格微观结构进行了CP-FE模拟，并与图像相关测量结果进行了比较。三维CP-FE预测可以很好地描述实测应变场，但宏观各向异性塑性模型和随机晶粒取向的CP-FE模拟都无法再现实测结果。Thin-Walled StructuresFree vibration and buckling behavior of porous orthotropic doubly-curved shallow shells subjected to non-uniform edge compression using higher-order shear deformation theoryFerruh Turan, Muhammed Karadeniz, Ertugrul Zerendoi:10.1016/j.tws.2024.112522利用高阶剪切变形理论研究非均匀边缘压缩下多孔正交各向异性双弯曲浅壳的自由振动和屈曲行为Due to the continuous enhancement of manufacturing technology for porous materials, it is expected to be increasingly used in aerospace, aviation, and other engineering applications, where the necessity for lightweight structures is paramount. Also, the non-uniform edge loads caused by service conditions, complex adjacent structures, and external loads lead to localized stress concentrations within the shells. Localized stress concentrations result in a loss of load-carrying capacity in specific regions, causing step-by-step failure of the shell. This study investigates the buckling and free vibration behavior of porous orthotropic doubly-curved shallow shells with four different porosity distribution patterns subjected to non-uniform edge compressive loads. The equations of motion of doubly-curved shallow shells are established by using higher-order shear deformation theory and Hamilton’s principle. Then, the pre-buckling in-plane stress distributions of doubly-curved shallow shells are determined and appended to the equations of motion. These fundamental partial differential equations are solved by Galerkin’s method, and the critical buckling load and natural frequency formulations are achieved. By comparing with the results in published literature, the feasibility and accuracy of present formulations are validated. Finally, systematic parametric studies are carried out to discuss the effects of different non-uniform edge compression patterns, porosity distribution patterns, porosity coefficients, aspect ratios, arc length-to-thickness ratios, radius-to-arc length ratios, orthotropy ratios, and shell types on the buckling and free vibration responses of porous orthotropic doubly-curved shallow shells. Parametric studies indicate that the reduction or increment in critical buckling loads (CBLs) and fundamental natural frequencies (FNFs) of spherical shells (SSs) are more sensitive than those of hyperbolic paraboloidal shells (HPSs). The CBLs and FNFs of SSs are larger than those of HPSs. The maximum and minimum CBLs are achieved for the triangular and uniform edge compression, respectively. The porosity effect is independent of edge compression pattern types.由于多孔材料制造技术的不断提高，预计它将越来越多地用于航空航天和其他工程应用，在这些应用中，轻量化结构的必要性是至关重要的。此外，使用条件、复杂相邻结构和外部载荷引起的非均匀边缘载荷导致壳内局部应力集中。局部应力集中导致特定区域的承载能力丧失，导致壳体逐步失效。研究了具有四种不同孔隙率分布模式的正交各向异性双弯曲浅壳在非均匀边缘压缩载荷作用下的屈曲和自由振动行为。利用高阶剪切变形理论和哈密顿原理，建立了双弯曲浅壳的运动方程。然后，确定了双弯曲浅壳在屈曲前的面内应力分布，并将其附加到运动方程中。用伽辽金法求解了这些基本的偏微分方程，得到了临界屈曲载荷和固有频率的表达式。通过与已发表文献的结果比较，验证了本公式的可行性和准确性。最后，进行了系统的参数化研究，讨论了不同非均匀边缘压缩模式、孔隙率分布模式、孔隙率系数、纵横比、弧长比、半径与弧长比、正交异性比和壳体类型对多孔正交各向异性双弯曲浅壳屈曲和自由振动响应的影响。参数研究表明，球壳的临界屈曲载荷（CBLs）和基频（FNFs）的减小或增加比双曲抛物面壳（hps）更敏感。SSs的CBLs和FNFs均大于hps。在三角形压缩和均匀边缘压缩下，分别获得了最大和最小的CBLs。孔隙率效应与边缘压缩模式类型无关。Stability analysis of a vertical cantilever pipe with lumped masses conveying two-phase flowXiao Wang, Guangming Fu, Huilin Jiao, Boying Wang, Baojiang Sun, Jian Sudoi:10.1016/j.tws.2024.112537集总质量垂直悬臂管输送两相流的稳定性分析This study investigates the vibration behavior of a vertical cantilever pipe conveying gas-liquid two-phase flow, focusing on the influence of lumped masses attached to the vertical cantilevered pipe. The governing motion equation based on small deflection Euler–Bernoulli beam theory is solved by using the generalized integral transforms technique. The proposed solution approach was first validated against available numerical and experimental results in the literature. The effects of the mass ratios, number and position of lumped masses on the stability of the pipe are investigated. Numerical results show that the parameters of the lumped masses affect significantly the stability of the pipe conveying two-phase flow, by altering the fluid–structure interaction dynamics and impacting natural frequencies and vibration modes of the pipe. Specifically, as the position of a single lumped mass moves downward from the fixed end to the free end, the critical flow velocity initially increases and subsequently decreases, thereby reducing the stability of pipe. Moreover, increasing the number of lumped masses significantly impacts the critical flow velocity due to the mass ratios and locations. Notably, modal “jumping” phenomena are observed, which demonstrate continuous shifts between equilibrium and non-equilibrium states in the cantilever pipes. These findings are crucial for ensuring the safe operation of pipes with discrete masses across various engineering applications.研究了输送气液两相流的垂直悬臂管道的振动特性，重点研究了垂直悬臂管道上附着的集中质量对管道振动特性的影响。采用广义积分变换技术求解了基于小挠度欧拉-伯努利梁理论的控制运动方程。提出的解决方法首先验证了现有的数值和实验结果在文献中。研究了集总质量比、集总质量个数和集总质量位置对管道稳定性的影响。数值计算结果表明，集总质量参数通过改变管道的流固耦合动力学，影响管道的固有频率和振动模态，对输送两相流的管道的稳定性有显著影响。具体来说，当单个集中质量的位置从固定端向下移动到自由端时，临界流速先增大后减小，从而降低了管道的稳定性。此外，由于质量比和质量位置的影响，集中质量数的增加会显著影响临界流速。值得注意的是，观察到模态“跳跃”现象，这表明悬臂管在平衡和非平衡状态之间连续转换。这些发现对于确保各种工程应用中离散质量管道的安全运行至关重要。A study on solid-shell finite element formulations applied to nonlinear thermoelastic analysis of thin-walled structuresKe Liang, Qiuyang Hao, Zheng Li, Qian Chengdoi:10.1016/j.tws.2024.112546应用于薄壁结构非线性热弹性分析的实壳有限元公式研究The solid-shell elements have shown great advantages in three-dimensional (3D) finite element (FE) simulation of thin-walled structures. To overcome the numerical lockings for 3D element with a large span-thickness ratio, the assumed natural strain (ANS) method combined by either the hybrid stress (HS) or enhanced assumed strain (EAS) formulations are commonly used. In this work, two types of finite element formulations of the solid-shell elements are developed for nonlinear thermoelastic analysis of thin-walled structures, which are termed as the “ANS+HS” and “ANS+EAS” formulations. Accordingly, two eight-node solid-shell elements (CSSH8 and CSSE8) are developed based on the “ANS+HS” and “ANS+EAS” formulations, respectively. The Green–Lagrange displacement-strain relation is applied to involve the geometrical nonlinearities, and both the thermal expansion and temperature-dependent material properties are considered. Nonlinear thermoelastic equilibrium equations are constructed in the framework of the two types of finite element formulations using the Hellinger–Reissner and conventional variational principles, respectively. The proposed method can easily realize three different coupling analyses for thermal-mechanical loads by modifying the parameters of nonlinear thermoelastic equilibrium equations. Numerical examples demonstrate that the proposed method using CSSH8 and CSSE8 elements traces the nonlinear thermoelastic response of the isogrid stiffened panel as accurately as the shell, solid-shell, and solid elements of ABAQUS. Furthermore, the path-following capability of the proposed method using the CSSH8 with “ANS+HS” formulation is slightly superior to that using the CSSE8 with “ANS+EAS” formulation, but both better than ABAQUS.实壳单元在薄壁结构的三维有限元模拟中显示出巨大的优势。为了克服大跨厚比三维单元的数值锁定问题，通常采用混合应力（HS）或增强假设应变（EAS）公式相结合的假设自然应变（ANS）方法。在这项工作中，开发了两种用于薄壁结构非线性热弹性分析的实体壳单元有限元公式，即“ANS+HS”和“ANS+EAS”公式。据此，分别基于“ANS+HS”和“ANS+EAS”的公式开发了两种八节点实体壳单元CSSH8和CSSE8。采用格林-拉格朗日位移-应变关系来考虑几何非线性，并考虑了材料的热膨胀和温度相关性质。分别利用Hellinger-Reissner变分原理和常规变分原理，在两类有限元公式的框架内构造了非线性热弹性平衡方程。该方法通过修改非线性热弹性平衡方程的参数，可以方便地实现三种不同的热-机械载荷耦合分析。数值算例表明，采用CSSH8和CSSE8单元对等网格加筋板的非线性热弹性响应的跟踪精度与ABAQUS中壳单元、固壳单元和实体单元的跟踪精度相当。此外，使用“ANS+HS”配方的CSSH8的路径跟踪能力略优于使用“ANS+EAS”配方的CSSE8，但均优于ABAQUS。A multi-bionic design strategy for modular energy absorption system based on interlocking suture integrated with Bouligand-like arranged perforationsJiaxuan Li, Chao Sui, Yuna Sang, Yichen Zhou, Zifu Zang, Yushun Zhao, Xiaodong He, Chao Wangdoi:10.1016/j.tws.2024.112553 基于互锁缝线和Bouligand-like排列孔的模块化能量吸收系统的多仿生设计策略Thin-walled tubes are widely used in the field of cushioning energy absorption as an ideal structural unit. However, the performance of the thin-walled tube system is greatly limited by the presence of redundant connection structures. To address these issues, a multi-bionic design strategy for high-performance modular system was developed in this work, which innovatively combines the robust joint structure of the interlocking suture with the efficient deformation mode of the Bouligand structures. In the design process, the suture-inspired system was studied separately, and its mechanical behaviors were investigated by FEM simulations and experiments. The results showed that the modular system has good structural scalability and tunable deformation mode, and can be adjusted on demand to accommodate different loads and geometric features. Furthermore, in order to reduce the weight and improve the deformation degree of the system, an optimization strategy inspired by the efficient deformation mode of the Bouligand structure was proposed by perforating a sequence of helix-arranged guide holes in the sidewalls of the tubes. The results showed that the double-helix perforated system can reduce the weight by 10% while increasing the specific energy absorption by 58% compared with the unperforated system. In addition, the specific energy absorption and energy absorption efficiency of the system are as high as 48.25 J/g and 56.17%, which is comparable to traditional honeycomb sandwich panels while retaining structural stability and adjustable performance. Therefore, this multi-bionic strategy can integrate the advantages of various natural structures and provide new insights for the design of high-performance protective systems.薄壁管作为一种理想的结构单元被广泛应用于减震吸能领域。然而，由于存在冗余连接结构，薄壁管系统的性能受到很大限制。为了解决这些问题，本研究开发了一种高性能模块化系统的多仿生设计策略，该策略创新地将互锁缝合线的坚固关节结构与Bouligand结构的有效变形模式相结合。在设计过程中，分别对缝合系统进行了研究，并通过有限元模拟和实验对其力学行为进行了研究。结果表明，该模块化系统具有良好的结构可扩展性和可调的变形方式，可根据需要进行调整，以适应不同的载荷和几何特征。在此基础上，基于Bouligand结构的有效变形模式，提出了一种在管的侧壁上穿孔一系列螺旋形导孔的优化策略，以减轻系统的重量，提高系统的变形程度。结果表明，与未打孔体系相比，双螺旋打孔体系可减轻10%的重量，提高58%的比能吸收。此外，该系统的比能量吸收和能量吸收效率分别高达48.25 J/g和56.17%，在保持结构稳定性和可调性能的同时，与传统的蜂窝夹芯板相当。因此，这种多仿生策略可以整合各种自然结构的优点，为高性能防护系统的设计提供新的见解。Aeroelastic analysis of a varying thickness blade with temperature-dependent sandwich materials by using isogeometric methodSaifeng Zhong, Guoyong Jin, Qingtao Gong, Yukun Chen, Na Wangdoi:10.1016/j.tws.2024.112568用等几何方法分析温度相关夹层材料变厚叶片的气动弹性Aeroelastic stability problem is a common vibration problem for rotating machinery. In this paper, the aeroelastic stability problem of the blade is treated as a matrix eigenvalue solution, in which the aerodynamic load is represented as a linear function of blade displacement and velocity by combining with the first-order piston theory. The mode coupled flutter characteristics of varying thickness (VK) blades are investigated under different thermal conditions. Two approximate models for blade thickness are adopted, including a linear variation in the spanwise direction and an airfoil-like variation along the chordwise direction. Based on the Non-Uniform Rational B-Spline (NURBS) functions in the isogeometric method, the continuous change of the blade thickness in each direction can be ensured. The sandwich materials are applied to resist the high temperatures which are considered to change only in the thickness direction. A flutter analysis model is developed for the sandwich blade with variable thickness in a steady-state thermal environment, aiming to determine the critical flutter boundaries. Furthermore, the influence of thermal conditions and airflow parameters on the flutter critical pressure and frequencies is considered to provide parameter influence laws of flutter boundary.气动弹性稳定性问题是旋转机械中常见的振动问题。本文结合一阶活塞理论，将叶片气动弹性稳定性问题视为矩阵特征值解，将气动载荷表示为叶片位移和速度的线性函数。研究了变厚叶片在不同热条件下的模态耦合颤振特性。叶片厚度采用两种近似模型，包括沿展向的线性变化模型和沿弦向的翼型型变化模型。基于等几何方法中的非均匀有理b样条（NURBS）函数，可以保证叶片厚度在各个方向上的连续变化。夹层材料被应用于抵抗高温，被认为只在厚度方向上改变。建立了变厚度夹层叶片在稳态热环境下的颤振分析模型，以确定其临界颤振边界。进一步考虑了热工况和气流参数对颤振临界压力和频率的影响，给出了颤振边界的参数影响规律。Failure behavior and damage model of composite sandwich panels under three-point bending fatigue loadFan Dong, Yazhi Li, Xin Qi, Weijie Ma, Chunping Zhou, Biao Lidoi:10.1016/j.tws.2024.112570三点弯曲疲劳载荷下复合材料夹芯板破坏行为及损伤模型Composite sandwich panels present a variety of damage modes due to their diverse components and variable structural parameters. This work conducted three-point bending static and fatigue tests on composite sandwich panels using specially designed fixtures to investigate their bending-shear characteristics and failure behaviors. The effects of core orientations, i.e., L-direction and W-direction, on the static strength, fatigue life, and fatigue crack initiation and propagation were compared. A stiffness-degradation-based fatigue damage model was constructed for the sandwich panels to describe the entire failure process from core cracking to core/plates debonding, achieving accurate modeling under the full load ratios. A differential evolution algorithm incorporating a penalty function was employed to optimize the model parameters under varying stresses. It was found that the designed fixture enables bi-directional fatigue loading and effectively avoids additional axial forces. Fatigue damage in sandwich panels resembles static but spans a wider area. While damage modes are similar in W-direction and L-direction, L-direction cores have higher stiffness and strength, and lower fatigue resistance in W-direction. Furthermore, the proposed fatigue damage model demonstrates excellent agreement with experimental results, achieving R2=0.968.复合材料夹芯板由于其构件的多样性和结构参数的多变性，呈现出多种损伤模式。本研究使用专门设计的夹具对复合材料夹芯板进行三点弯曲静态和疲劳试验，以研究其弯曲剪切特性和破坏行为。比较了芯材取向（l向和w向）对静强度、疲劳寿命、疲劳裂纹萌生和扩展的影响。建立了基于刚度退化的夹层板疲劳损伤模型，描述了夹层板从核心开裂到核心/板剥离的整个破坏过程，实现了在全载荷比下的精确建模。采用一种结合惩罚函数的微分进化算法对变应力下的模型参数进行优化。结果表明，所设计的夹具能够实现双向疲劳加载，并有效地避免了额外的轴向力。夹芯板的疲劳损伤类似于静态损伤，但范围更广。w方向和l方向的损伤模式相似，但l方向的岩心刚度和强度较高，w方向的疲劳抗力较低。此外，所提出的疲劳损伤模型与实验结果吻合良好，达到R2= 0.968。Experimental study of composite cold-formed steel and timber flooring systems with innovative shear connectorsNathan Vella, Pinelopi Kyvelou, Spiridione Buhagiar, Leroy Gardnerdoi:10.1016/j.tws.2024.112571新型剪切接头冷弯钢板与木地板复合系统的试验研究An experimental investigation into the structural response of cold-formed steel-timber composite flooring systems with innovative and irregularly spaced shear connectors is presented in this paper. Five composite beam tests and a series of supporting material and push-out tests were carried out. The obtained results showed that the innovative shear connectors enabled the generation of considerable composite action, resulting in up to about 45% increases in load-carrying capacity and 15% and 20% increases in the initial and mid-range stiffnesses respectively over the non-composite system. Methods for predicting the effective flexural stiffness and moment capacity of the examined cold-formed steel-timber composite beams are presented and validated against the derived physical test data. It is shown that accurate predictions for both the flexural stiffness and moment capacity can be obtained, with mean prediction-to-test ratios of 0.93 and 0.91 respectively.本文对冷弯型钢-木材复合楼板系统的结构响应进行了试验研究。进行了5次组合梁试验和一系列支撑材料和推出试验。结果表明，创新的剪切连接件能够产生相当大的复合作用，与非复合系统相比，承载能力提高了约45%，初始刚度和中期刚度分别提高了15%和20%。提出了冷弯型钢-木材组合梁有效抗弯刚度和弯矩承载力的预测方法，并根据推导的物理试验数据进行了验证。结果表明，该方法可以准确预测抗弯刚度和弯矩承载力，平均预测与试验比分别为0.93和0.91。Experimental testing and plastic strain analysis of high strength steel longitudinal plate to tubular X jointsIhyun Ryu, Seon-Hu Kim, Cheol-Ho Leedoi:10.1016/j.tws.2024.112573高强钢纵板-管X接头试验试验及塑性应变分析Applying high strength steels to tubular joints can increase the propensity to fracture failure due to their lower ductility. However, to simulate the fracture behavior in the finite element (FE) analysis, sophisticated material damage model with rigorous fracture criteria should be incorporated. Recently, the latest draft of ISO 14346 has advocated the use of 5% strain limit in FE analysis of tubular joints. The strain limit concept has been further developed by the authors’ previous work, for its use as a practical alternative to the complicated material damage model. Specifically, a lowered limit of 2.5% was recommended for longitudinal plate to circular hollow section (CHS) joints subjected to in-plane bending. This study extends the strain limit investigation to longitudinal plate to tubular X joints subjected to tensile loads. An experimental program is first presented which included both CHS and rectangular hollow section (RHS) chord members fabricated from two high strength steels with nominal yield stresses of 460 MPa and 700 MPa. Based on test-validated supplemental numerical analyses, it is suggested that the joint load corresponding to 2.5% strain limit can be taken as the load-bearing capacity to suppress occurrence of a fracture failure for the tubular joint configurations considered in this study.由于高强度钢的延性较低，在管状接头上应用高强度钢会增加其断裂破坏的可能性。然而，为了在有限元分析中模拟断裂行为，需要采用复杂的材料损伤模型和严格的断裂准则。最近，ISO 14346的最新草案提倡在管状节点的有限元分析中使用5%的应变极限。应变极限概念在作者之前的工作中得到了进一步的发展，因为它可以作为复杂材料损伤模型的实用替代方案。具体而言，建议纵向板-圆空心节（CHS）节点受面内弯曲的降低限值为2.5%。本研究将应变极限研究扩展到受拉伸载荷作用的纵向板-管X节点。首先提出了一种实验方案，其中包括由两种高强度钢制成的CHS和矩形空心截面（RHS）弦杆，标称屈服应力为460 MPa和700 MPa。基于试验验证的补充数值分析，建议采用2.5%应变极限对应的接头载荷作为本研究管状接头形态抑制断裂破坏发生的承载能力。Buckling Behavior of Thin-walled Cold-formed Steel Latticed Column with Lacings under Axial CompressionChao Hu, Rui Cheng, Yuhang Wang, Xuhong Zhou, Zihao Liudoi:10.1016/j.tws.2024.112574带拉筋的薄壁冷弯型钢格肋柱轴压屈曲行为Extensive research has been undertaken on built-up cold-formed steel (CFS) column with I-shaped or box-shaped section. However, there has been little attention given to lattice CFS columns, particularly regarding their buckling performance and the design methods for determining buckling capacity. This paper proposes a latticed CFS column, formed by combining two G-shaped (complex edge stiffener) channels using lacings (LCCFS). Eighteen LCCFS columns were tested under axial compression, divided into two groups with web widths of 75 mm and 200 mm. The experimental results demonstrated that no distortional buckling failure occurred in the G-shaped channels of all specimens, mainly due to the constraint provided by lacings on the flanges. A general consistency in the ultimate bearing capacities and failure modes was observed among duplicate specimens. Specimens with a small slenderness ratio predominantly experienced local buckling failure, leading to a more abrupt failure. In contrast, specimens characterized by a large slenderness ratio primarily demonstrated failure due to global buckling. The specimens with larger web width-to-thickness ratios exhibited earlier and more pronounced local buckling, resulting in a reduction in axial compressive stiffness. Furthermore, FE models have been developed to analyze the effects of different parameters on the axial compressive buckling performance of LCCFS columns. The existing direct strength method exhibited notable deviations in predicting axial compressive buckling capacity of LCCFS column, which are deemed unsatisfactory. Based on direct strength method, a method was proposed for determining the axial compressive buckling capacity of LCCFS column.冷弯型钢（CFS）组合柱的工字钢和箱式型钢截面进行了广泛的研究。然而，对晶格CFS柱的屈曲性能和屈曲承载力的设计方法的研究却很少。本文提出了一种网格CFS柱，由两个g形（复合边加强）通道组合而成，采用拉筋（LCCFS）。对18根LCCFS柱进行轴压试验，将其分为腹板宽度为75 mm和200 mm两组。试验结果表明，所有试件的g形通道均未发生畸变屈曲破坏，这主要是由于法兰上的绑带提供了约束。在重复试件中观察到极限承载力和破坏模式的总体一致性。当试件长细比较小时，主要发生局部屈曲破坏，破坏更为突然。相比之下，具有大长细比的试件主要表现为由于整体屈曲而导致的破坏。腹板宽厚比较大的试件表现出更早和更明显的局部屈曲，导致轴向压缩刚度降低。此外，还建立了有限元模型，分析了不同参数对LCCFS柱轴压屈曲性能的影响。现有的直接强度法在预测LCCFS柱轴压屈曲能力时存在明显偏差，不能令人满意。基于直接强度法，提出了一种确定LCCFS柱轴压屈曲能力的方法。Bending response of cover-plated CFS built-up sections: Testing, numerical parametric analysis and designS. Kavin Kumar, M. Anbarasu, Mohammad Adil Dardoi:10.1016/j.tws.2024.112576覆层CFS组合截面的弯曲响应：试验、数值参数分析与设计This study investigates the bending response of cover-plated cold-formed steel (CPCFS) built-up sections comprising of plain channel members under pure bending achieved through four-point loading, both experimentally and numerically. Channels were appropriately spaced back-to-back and screw-fastened at the flanges using cover-plates on the tension and compression sides. This novel design for the CPCFS built-up section combines the benefits of box-profile (closed sections) and I-profile (open sections), including high strength-to-weight ratio, simplified fabrication, and enhanced torsional rigidity. Eight CPCFS built-up sections with different cross-sectional aspect ratios were tested for bending about the major axis under simply supported end conditions. Flexural strengths, failure modes, and moment-curvature plots were discussed. Subsequently, a finite element model was developed in ABAQUS and validated against the test response obtained. Afterwards, an extensive parametric analysis was conducted to assess the variational effect of aspect ratios, cross-sectional slenderness, and plate slenderness on the ultimate moment capacity of the CPCFS built-up beams. Finally, the adequacy of the codified Continuous Strength Method (CSM) and Direct Strength Method (DSM) for CPCFS built-up beams was evaluated. Generally, it was observed that the flexural strengths predicted by the codified CSM and DSM for CPCFS built-up beams were unconservative and conservative, respectively. Suitable modifications were proposed to both DSM and CSM to accurately predict the flexural strength of CPCFS built-up beams, which were eventually verified through a reliability analysis.本研究研究了覆盖冷弯型钢（CPCFS）由平面通道构件组成的组合截面在四点加载纯弯曲下的弯曲响应，包括实验和数值模拟。通道被适当间隔背靠背和螺丝固定在法兰上使用盖板在拉伸和压缩方面。这种新颖的CPCFS组合截面设计结合了箱型（封闭截面）和i型（开放截面）的优点，包括高强度重量比、简化制造和增强的抗扭刚度。在简支端部条件下，对8个不同纵横比的CPCFS组合截面进行了绕轴弯曲试验。讨论了抗弯强度、破坏模式和弯矩曲率图。随后，在ABAQUS中建立了有限元模型，并根据得到的试验响应进行了验证。随后，进行了广泛的参数分析，以评估长径比、截面长细比和板长细比对CPCFS组合梁极限弯矩承载力的变化影响。最后，对规范的连续强度法（CSM）和直接强度法（DSM）对CPCFS组合梁的适用性进行了评价。总的来说，CPCFS组合梁的CSM和DSM预测的抗弯强度分别是非保守性和保守性。为了准确预测CPCFS组合梁的抗弯强度，分别对DSM和CSM进行了适当的修正，并通过可靠性分析对修正结果进行了验证。Experimental investigation of high-velocity impact response and compression after impact behavior of continuous carbon fiber thermoplastic compositesGang Wei, Chenyu Hao, Hongwei Jin, Yunfei Dengdoi:10.1016/j.tws.2024.112578连续碳纤维热塑性复合材料高速冲击响应及冲击后压缩性能试验研究In order to meet the urgent needs for the application of thermoplastic composite structures in aircraft manufacturing and other fields, the impact resistance and damage tolerance of continuous carbon fiber reinforced thermoplastic composite laminates (CCFRTP) are investigated by high-velocity impact (HVI) and compression after impact (CAI) experiments in this paper. The impact experiment results show that the ballistic response of laminates under small-angle conventional impact is similar, and the impact resistance of laminates under large-angle oblique impact is significantly improved. The failure mechanism of laminates under high-velocity impact is revealed by analyzing the impact process of the projectile, the energy absorption level, the failure morphology and internal damage degree of laminates comprehensively. It is clear that the impact angle and velocity of the projectile will significantly affect the coupling form of the failure mechanism and lead to differentiated results. The results of in-plane compression experiment of laminates with impact damage show that the bearing capacity of laminates is significantly weakened by high velocity impact damage, and the residual strength of laminates is directly determined by the mode and degree of impact damage. In particular, through the analysis of the energy absorption mechanism, a trend prediction model of ballistic limit value with impact angle is established, and the influence of high-velocity impact damage on the residual strength of laminates is revealed. This study provides a better understanding of the mechanical response of thermoplastic composite structures to high-velocity impact loads.为了满足热塑性复合材料结构在飞机制造等领域应用的迫切需要，本文通过高速冲击（HVI）和冲击后压缩（CAI）实验，研究了连续碳纤维增强热塑性复合材料层合板（CCFRTP）的抗冲击性和损伤容限。冲击实验结果表明，层合板在小角度常规冲击下的弹道响应相似，而在大角度斜冲击下层合板的抗冲击性能明显提高。通过对弹丸的冲击过程、能量吸收水平、层合板的破坏形态和内部损伤程度的综合分析，揭示了层合板在高速冲击下的破坏机理。可见，弹丸的冲击角度和速度会显著影响破坏机制的耦合形式，导致不同的结果。冲击损伤层合板的面内压缩实验结果表明，高速冲击损伤会显著削弱层合板的承载能力，冲击损伤的方式和程度直接决定层合板的残余强度。特别是通过对能量吸收机理的分析，建立了弹道极限值随冲击角度变化的趋势预测模型，揭示了高速冲击损伤对层合板残余强度的影响。该研究为热塑性复合材料结构在高速冲击载荷作用下的力学响应提供了更好的理解。An experimental study on web-bearing resistance of cold-formed steel sigma-shaped sections with web holes under interior-two-flange loading caseBoshan Chen, Yecheng Dai, Wei Wang, Youtian Wang, Lisheng Luo, Peng Dai, James Limdoi:10.1016/j.tws.2024.112579内双法兰工况下带腹板孔的冷弯sigma型钢截面腹板承载抗力试验研究Cold-formed steel (CFS) sigma-shaped sections used as flooring joists and bearers are commonly fabricated with web holes to accommodate building services. These sections featuring web stiffeners and curved lips exhibit lower web-bearing resistance than traditional lipped channel sections. However, the web-bearing resistance of CFS sigma-shaped sections with web holes has not been thoroughly investigated. To address this gap, a detailed experimental investigation was conducted, testing 29 CFS sigma-shaped sections with web holes under an interior-two-flange (ITF) loading case. For comparison, specimens without web holes were also tested. Variables such as hole diameter ratio, hole location, bearing length, and flange condition were examined. A finite element (FE) model was developed and validated against the test results. The results indicated that the web-bearing resistance for specimens with web holes was reduced by 24.0% on average. To assess the accuracy of existing design specifications, the test results were compared against the design strengths predicted by the American Iron and Steel Institute (AISI) (2016), Australian and New Zealand Standards (AS/NZS) (2018), European Standard (EC3) (2006), and Uzzaman et al. (2012). The comparison revealed that the design strength predicted by Uzzaman et al. (2012) agreed well with the test results.冷弯型钢（CFS）用作地板托梁和支座的西格玛形截面通常带有腹板孔，以容纳建筑设备。这些部分具有腹板加强和弯曲的嘴唇表现出较低的腹板承载阻力比传统的唇形通道部分。然而，具有腹板孔的CFS σ形截面的腹板阻力尚未得到深入的研究。为了解决这一问题，进行了详细的实验研究，在内部双法兰（ITF）加载情况下测试了29个带有腹板孔的CFS西格玛形截面。为了比较，没有网孔的标本也进行了测试。考察了孔直径比、孔位置、轴承长度和法兰状态等变量。建立了有限元模型，并对试验结果进行了验证。结果表明，有孔洞的试件的耐蹼阻力平均降低24.0%。为了评估现有设计规范的准确性，将测试结果与美国钢铁协会（AISI）（2016）、澳大利亚和新西兰标准（AS/NZS）（2018）、欧洲标准（EC3）（2006）和Uzzaman等人（2012）预测的设计强度进行了比较。对比发现Uzzaman et al.（2012）预测的设计强度与试验结果吻合较好。Combined Bending-Torsion and Compression-Bending-Torsion Behaviours of Reinforced Concrete-Filled Thin-Walled Corrugated Steel TubesYong Fang, Yuyin Wang, Hua Yang, Yajin Wangdoi:10.1016/j.tws.2024.112567薄壁波纹钢管钢筋混凝土弯曲-扭转和压缩-弯曲-扭转联合性能研究Reinforced concrete-filled thin-walled galvanized corrugated steel tube (RCFCST) is a novel composite member that has application potential in extremely corrosive environments and seismic activity regions. A series of preliminary works have been conducted on its compressive, flexural, shear, and torsional behaviour. However, the combined loading condition is almost inevitable in practice. The correlations between the flexural and torsional behaviour of RCFCSTs are unique due to the special spiral corrugated profile, which is unclear and needs to be addressed. This paper, therefore, presents an experimental investigation of the RCFCST under combined bending-torsion and compression-bending-torsion loads, encompassing the main test variables of torsion-to-bending ratios, torsional directions, and axial compression ratios. The loading set-up and instruments have been introduced in detail. The failure modes, lateral load versus lateral displacement curves, bending moment versus flexural lateral displacement curves, torsion moment versus torsional angle curves, and strain distributions are carefully addressed. The working mechanisms of the RCFCST under combined loads are discussed, with a particular explanation of the dependent behaviour on the torsion-to-bending ratios and torsional directions. The applicability of the existing design methods for the bearing capacity of RCFCST specimens under combined loads is examined carefully, with specific design suggestions proposed.薄壁镀锌波纹钢管（RCFCST）是一种新型的复合材料构件，在极端腐蚀环境和地震活动性地区具有应用潜力。对其压缩、弯曲、剪切和扭转性能进行了一系列初步研究。然而，在实际应用中，组合加载几乎是不可避免的。由于特殊的螺旋波纹型材，rcfcst的弯曲和扭转行为之间的相关性是独特的，这是不清楚的，需要解决。因此，本文对RCFCST在弯曲-扭转和压缩-弯曲-扭转组合载荷下的试验进行了研究，包括扭弯比、扭转方向和轴压比等主要试验变量。详细介绍了加载装置和仪器。对破坏模式、侧向荷载与侧向位移曲线、弯矩与受弯侧向位移曲线、扭转矩与扭转角曲线以及应变分布进行了详细分析。讨论了复合荷载作用下RCFCST的工作机理，并特别解释了扭转弯曲比和扭转方向的依赖行为。仔细考察了现有设计方法对组合式荷载作用下RCFCST试件承载力的适用性，并提出了具体的设计建议。3D bi-directional auxetic square metastructure with programmable thermal expansion and Poisson's ratioLu-Yao Wang, Hai-Tao Liu, Kang-Jia Liudoi:10.1016/j.tws.2024.112569具有可编程热膨胀和泊松比的三维双向互生方形元结构Multifunctional integration research on metastructures has become the current development trend and hotspot, especially satellite platforms and hypersonic aircraft in the aerospace field. A 3D bi-directional auxetic square metastructure (BASM) with the programmable coefficient of thermal expansion (CTE) and Poisson's ratio (PR) is designed through the combination of re-entrant hexagonal structures and bi-material triangles. Specimens in the form of the 12 array are designed and fabricated through 3D printing. The correctness of the results of finite element analysis (FEA) of the BASM is verified by uniaxial compression experiments. Additionally, FEA is adopted to investigate the effective mechanical properties of the BASM with the form of the 23 array, and deformation mechanisms are further explored. Results indicate that the CTE, PR, and stiffness of the BASM depend on material combinations and geometric parameters. Under thermal and mechanical loads, the BASM achieves bi-directional regulation of the CTE and PR, encompassing both axial and circumferential deformations. Notably, the deformation mechanisms and critical conditions of the BASM are explored under the thermo-mechanical load. A novel strategy for programming the PR of the BASM is proposed in addition to changing the geometric parameters and the material combinations.元结构的多功能集成研究已成为当前航空航天领域的发展趋势和热点，特别是卫星平台和高超声速飞行器。设计了一种具有可编程热膨胀系数（CTE）和泊松比（PR）的三维双向增减方形元结构（BASM），该结构将可重新进入的六边形结构与双材料三角形相结合。通过3D打印设计并制作12阵列形式的样品。通过单轴压缩试验，验证了该结构有限元分析结果的正确性。此外，采用有限元法研究了23阵列形式的BASM的有效力学性能，并进一步探讨了变形机理。结果表明，复合材料的CTE、PR和刚度与材料组合和几何参数有关。在热载荷和机械载荷下，BASM实现了CTE和PR的双向调节，包括轴向和周向变形。值得注意的是，研究了热-机械载荷作用下BASM的变形机理和临界条件。除了改变几何参数和材料组合外，还提出了一种新的设计策略。Experimental study on multiple self-healing and impact properties of 2D carbon fiber fabric-reinforced epoxy composites with shape memory propertiesEnbo ZHAO, Qiheng XIA, Lulu LIU, Feng JIN, Gang LUO, Zhenhua ZHAO, Wei CHENdoi:10.1016/j.tws.2024.112549具有形状记忆性能的二维碳纤维增强环氧复合材料多次自愈和冲击性能的实验研究Fiber-reinforced thermoset polymers are widely used in aerospace as a material with excellent performance. However, for the low-velocity impact damage to which they are most susceptible, existing repair methods are difficult to maintain the aerodynamic performance of the components (back to its pre-damage shape) after repair. In this study, the multiple impact deformation recovery, internal damage healing, and post-repair impact properties of epoxy-PCL (ε-caprolactone) 2D carbon fiber fabric-reinforced polymers with shape memory and self-healing properties were investigated. The material is manufactured using a hot press tank-prepreg process, curing at 160 degrees for 3.5 hours at 6 atmospheres. The results show that the incorporation of thermoplastic PCL into the composite matrix can enhance the self-healing ability and impact resistance of the material. Composites after lower energy impacts retain their structural integrity and mechanical properties after healing. Materials can recover effectively from a single impact, but repeated impacts can lead to more extensive damage, which makes healing more difficult and causes a decrease in Healing efficiency. The shape memory effect of composites can restore plastic deformation caused by impact, which highlights the potential of shape memory smart composites for aerospace applications.纤维增强热固性聚合物作为一种性能优异的材料在航空航天领域得到了广泛的应用。然而，对于它们最容易受到的低速冲击损伤，现有的修复方法很难在修复后保持部件的气动性能（恢复到损伤前的形状）。本研究研究了具有形状记忆和自修复性能的环氧树脂-聚己内酯（ε-己内酯）二维碳纤维织物增强聚合物的多次冲击变形恢复、内部损伤愈合和修复后冲击性能。该材料使用热压罐预浸工艺制造，在160度下在6个大气压下固化3.5小时。结果表明，在复合材料基体中掺入热塑性PCL可以增强材料的自愈能力和抗冲击性能。复合材料经过低能量冲击后，在愈合后仍能保持其结构完整性和力学性能。材料可以从一次撞击中有效地恢复，但多次撞击会导致更广泛的伤害，这使得愈合更加困难，并导致愈合效率降低。复合材料的形状记忆效应可以恢复冲击引起的塑性变形，这凸显了形状记忆智能复合材料在航空航天领域的应用潜力。Numerical simulation for microstructure control in wire arc additive manufacturing of thin-walled structuresLichao Zhang, Hongshan Zhou, Jingyuan Chen, Hongyang Wang, Weiwei Liu, Zhaodong Zhang, Gang Song, Liming Liu, Zhao Zhangdoi:10.1016/j.tws.2024.112581薄壁结构电弧丝增材制造微结构控制的数值模拟The difference of cooling rates on the surface and the interior of thin-walled structures leads to significant differences of microstructures in additive manufacturing (AM). To reveal the microstructure control in wire arc additive manufacturing of thin-walled structures, a gas-heat coupling model with experimental validation is proposed. The computational accuracy can reach 96% in prediction of temperatures and microstructures. Increasing the preheating or scanning speed leads to a higher probability of heterogeneous nucleation on the surface of thin-walled structures. When the pre-heating is increased from 550 K to 750 K, the proportion of equiaxed grains increases by 20.8%. When the gas flow rate of super cooling is increased from 20 L/min to 30 L/min, the size of equiaxed grains is decreased from 0.33 mm to 0.23 mm on the surface, and the width of columnar grains is decreased from 0.53 mm to 0.42 mm in the interior. This is due to the significant differences in cooling rates in thin-walled structures.在增材制造（AM）中，薄壁结构表面和内部冷却速率的差异导致了微观组织的显著差异。为了揭示薄壁结构电弧增材制造过程中的微观结构控制，提出了一种经实验验证的气热耦合模型。在温度和组织预测方面，计算精度可达96%。增大预热或扫描速度，薄壁结构表面非均质成核的可能性增大。当预热温度从550 K增加到750 K时，等轴晶的比例增加了20.8%。当过冷气体流速从20 L/min增加到30 L/min时，表面等轴晶粒尺寸从0.33 mm减小到0.23 mm，内部柱状晶粒宽度从0.53 mm减小到0.42 mm。这是由于薄壁结构中冷却速率的显著差异。Semi-analytical formulation to predict the vibroacoustic response of a fluid-loaded plate with ABH stiffenersDaniel Martins, Mahmoud Karimi, Laurent Maxitdoi:10.1016/j.tws.2024.112539用半解析公式预测含ABH加强板的声振响应Stiffened structures are widely used in aeronautics, marine and rail industries. When stiffeners are integrated into host structures, so-called Bloch-Floquet waves are generated due to interactions between the host’s flexural waves and the stiffeners’ flexural and torsional waves. It is reported in the literature that these waves are often the source of undesirable noise and vibrations when the stiffened structure is excited by a force. To mitigate unwanted noise and vibrations from the stiffened structures, this study proposes to replace common rectangular stiffeners with acoustic black hole (ABH) stiffeners. To do this, a semi-analytical model is initially developed in the wavenumber domain to predict the forced vibroacoustic response of a 2D fluid-loaded infinite plate with stiffeners on one side. In the proposed model, the stiffeners are characterised by their translational and rotational dynamic stiffnesses which can be estimated by a finite element method (FEM). These dynamic stiffnesses are then coupled with the analytical formulation of the fluid-loaded plate to obtain the expressions of the spectral displacement and radiated pressure. Comparisons of the results in terms of the plate’s mean quadratic velocity and radiated sound power for the rectangular and ABH stiffeners show that by using the ABH stiffeners instead of the conventional stiffeners, one can significantly reduce the vibroacoustic response of light/heavy fluid-loaded plates.加劲结构广泛应用于航空、船舶、铁路等行业。当加劲筋集成到宿主结构中时，由于宿主的弯曲波与加劲筋的弯曲波和扭转波之间的相互作用，产生了所谓的Bloch-Floquet波。据文献报道，当加筋结构被力激发时，这些波往往是不希望的噪声和振动的来源。为了减轻加劲结构产生的噪声和振动，本研究提出用声学黑洞加劲板代替普通矩形加劲板。为此，首先在波数域中建立了半解析模型，以预测一侧有加强筋的二维流体加载无限板的强迫振动声响应。在该模型中，加劲筋的特征是其平移和旋转动态刚度，可以用有限元法（FEM）估计。然后将这些动态刚度与流载板的解析表达式耦合，得到谱位移和辐射压力的表达式。对矩形加筋和ABH加筋板的平均二次速度和辐射声功率的比较结果表明，用ABH加筋代替常规加筋可以显著降低轻/重流体加载板的声振响应。来源：复合材料力学仿真Composites FEM
