【新文速递】2024年9月1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 2 篇，Mechanics of Materials 5 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 5 篇

International Journal of Solids and Structures

Hybrid intelligent framework for designing band gap-rich 2D metamaterials

Mohamed Shendy, Mohammad A. Jaradat, Maen Alkhader, Bassam A. Abu-Nabah, T.A. Venkatesh

doi:10.1016/j.ijsolstr.2024.113053

设计富带隙二维超材料的混合智能框架

An artificial intelligence machine learning-based design framework is proposed to design lattice-based metamaterials with hexagonal symmetry that deliver wide band gaps at user-desired frequency ranges between 0 and 1000 kHz. The design approach starts by selecting a traditional, easy-to-manufacture parent lattice-based material that does not necessarily exhibit wide or functional band gaps. Subsequently, the parent lattice is transformed into a band-gap-rich lattice by superposing periodic triangular-shaped perturbations (i.e., zigzag-sine-based curvatures) with controllable frequencies and magnitudes on its ligaments. Finally, the frequency and magnitude parameters needed to deliver a specific band gap between 0 and 1000 kHz are determined using a hybrid intelligent framework, developed based on an Adaptive Neuro-Fuzzy Inference Systems (ANFIS). The ANFIS network integrates fuzzy logic expert models and artificial neural networks’ machine learning capabilities. Such a hybrid network is known for its ability to model strongly nonlinear and complex data. The data used in training the ANFIS models is generated using parametric finite element-based simulations where band gaps corresponding to a wide range of perturbation frequencies and magnitudes are computationally determined. The parametric study showed a nonlinear and complex topology-band gap characteristic relation; however, the Adaptive Neuro-Fuzzy Inference System (ANFIS) proved capable of modeling the observed complex topology-band gap behavior efficiently. The accuracy of the ANFIS models exceeded 99 % in several design ranges (i.e., perturbation parameters ranges). These were designated as high-accuracy design regions and were highlighted in the proposed design approach. Using multiple case studies with different band gap requirements, the ANFIS-based design framework proved effective in delivering customized lattice-based metamaterials with user-defined band gap frequencies.

提出了一种基于人工智能机器学习的设计框架，用于设计具有六边形对称性的基于晶格的超材料，该材料可以在0到1000 kHz之间的用户所需频率范围内提供宽带隙。设计方法首先选择一种传统的、易于制造的母晶格基材料，这种材料不一定表现出宽的或功能性的带隙。随后，通过在其韧带上叠加具有可控频率和幅度的周期性三角形扰动(即基于之字形的曲率)，将母晶格转化为富带隙晶格。最后，使用基于自适应神经模糊推理系统(ANFIS)开发的混合智能框架确定提供0到1000 kHz之间特定带隙所需的频率和幅度参数。ANFIS网络集成了模糊逻辑专家模型和人工神经网络的机器学习能力。这种混合网络以其对强非线性和复杂数据建模的能力而闻名。用于训练ANFIS模型的数据是使用基于参数有限元的模拟生成的，其中对应于大范围扰动频率和幅度的带隙是通过计算确定的。参数化研究显示出一种非线性复杂的拓扑带隙特性关系;然而，自适应神经模糊推理系统(ANFIS)被证明能够有效地模拟观察到的复杂拓扑带隙行为。在几个设计范围内(即摄动参数范围)，ANFIS模型的精度超过99% %。这些被指定为高精度设计区域，并在建议的设计方法中突出显示。通过对不同带隙要求的多个案例研究，基于anfiss的设计框架被证明可以有效地提供具有用户定义带隙频率的定制晶格基超材料。

Journal of the Mechanics and Physics of Solids

A generalized strain model for spectral rate-dependent constitutive equation of transversely isotropic electro-viscoelastic solids

M.H.B.M. Shariff, R. Bustamante, J. Merodio

doi:10.1016/j.jmps.2024.105838

横向各向同性电粘弹性固体谱率相关本构方程的广义应变模型

We model the constitutive equation for nonlinear electro-viscoelastic transversely isotropic solids with short term memory via a generalized strain method, where the method is a change with respect to the methods that have been done in the last decades regarding mechanics of nonlinear solids. Our generalized strain model uses spectral invariants with a clear physical interpretation and hence they are attractive for use in experiments. The constitutive equation contains single-variable functions, which are easy to deal with when compared to multivariable functions. The effects of viscosity and electric fields are analysed via the boundary value problem results. The efficacy the proposed prototype is scrutinized by comparing our theory with experimental data.

我们通过广义应变方法对具有短期记忆的非线性电粘弹性横各向同性固体的本构方程进行了建模，该方法是对过去几十年来关于非线性固体力学的方法的一种改变。我们的广义应变模型使用具有明确物理解释的谱不变量，因此它们在实验中具有吸引力。本构方程包含单变量函数，与多变量函数相比，单变量函数易于处理。通过边值问题的结果分析了黏度和电场的影响。通过与实验数据的比较，验证了该模型的有效性。

Rayleigh surface waves of extremal elastic materials

Yu Wei, Yi Chen, Wen Cheng, Xiaoning Liu, Gengkai Hu

doi:10.1016/j.jmps.2024.105842

极端弹性材料的瑞利表面波

Extremal elastic materials here refer to a specific class of elastic materials whose elastic matrices exhibit one or more zero eigenvalues, resulting in soft deformation modes that, in principle, cost no energy. They can be approximated through artificially designed solid microstructures. Extremal elastic materials have exotic bulk wave properties unavailable with conventional solids due to the soft modes, offering unprecedented opportunities for manipulating bulk waves, e.g., acting as phonon polarizers for elastic waves or invisibility cloaks for underwater acoustic waves. Despite their potential, Rayleigh surface waves, crucially linked to bulk wave behaviors of such extremal elastic materials, have largely remained unexplored so far. In this paper, we theoretically investigate the propagation of Rayleigh waves in extremal elastic materials based on continuum theory and verify our findings with designed microstructure metamaterials based on pantographic structures. Dispersion relations and polarizations of Rayleigh waves in extremal elastic materials are derived, and the impact of higher order gradient effects is also investigated by using strain gradient theory. This study provides a continuum model for exploring surface waves in extremal elastic materials and may stimulate applications of extremal elastic materials for controlling surface waves.

这里的极端弹性材料是指一类特定的弹性材料，其弹性矩阵表现出一个或多个零特征值，从而产生原则上不消耗能量的软变形模式。它们可以通过人工设计的固体微观结构来近似。由于软模，极端弹性材料具有传统固体所不具备的奇异体波特性，为操纵体波提供了前所未有的机会，例如，作为弹性波的声子偏振器或水声波的隐形斗篷。尽管瑞利表面波具有潜力，但与这种极端弹性材料的体波行为密切相关的瑞利表面波迄今在很大程度上仍未被探索。本文基于连续介质理论，从理论上研究了瑞利波在极端弹性材料中的传播，并通过基于受电弓结构的微结构超材料的设计验证了我们的发现。推导了极端弹性材料中瑞利波的色散关系和极化，并利用应变梯度理论研究了高阶梯度效应的影响。该研究为探索极弹性材料的表面波提供了一个连续模型，并可能促进极弹性材料在控制表面波方面的应用。

Mechanics of Materials

Spatio-temporal physics-informed neural networks to solve boundary value problems for classical and gradient-enhanced continua

Duc-Vinh Nguyen, Mohamed Jebahi, Francisco Chinesta

doi:10.1016/j.mechmat.2024.105141

基于时空物理的神经网络解决经典连续体和梯度增强连续体的边值问题

Recent advances have prominently highlighted physics informed neural networks (PINNs) as an efficient methodology for solving partial differential equations (PDEs). The present paper proposes a proof of concept exploring the use of PINNs as an alternative to finite element (FE) solvers in both classical and gradient-enhanced solid mechanics. To this end, spatio-temporal PINNs are designed to represent continuous solutions of boundary value problems within spatio-temporal space. These PINNs directly incorporate the equilibrium and constitutive equations in their differential and rate forms, bypassing the requirement for incremental implementation. This simplifies application of PINNs to solve complex mechanical problems, particularly those involved in the context of gradient-enhanced continua. Moreover, traditional meshing is no longer required as it is replaced by a point cloud, making it possible to overcome meshing drawbacks. The results of this investigation prove the effectiveness of the proposed methodology, especially with regards to non-monotonic loading conditions and irreversible plastic deformation. Compared to classical FE approaches, the proposed spatio-temporal PINNs are more readily applied to complex problems, which are tackled in their raw form. This is especially true for gradient-enhanced continuum problems, where there is no need to introduce additional degrees of freedom as in classical FE approaches. However, PINNs training generally requires more computation time, a challenge that can be mitigated by employing the concept of transfer learning as shown in this paper. This concept, which is very useful when performing parametric studies, involves applying knowledge grained from solving one problem to another different but related one. The use of PINNs as mechanical solvers is shown to be highly promising in the forthcoming era, where advancements in GPU technology can further enhance their performance in terms of computation time.

最近的进展突出强调了物理信息神经网络(pinn)作为求解偏微分方程(PDEs)的有效方法。本文提出了一个概念证明，探索在经典和梯度增强固体力学中使用pinn作为有限元(FE)求解器的替代方案。为此，设计时空pin来表示时空空间中边值问题的连续解。这些pin n直接将平衡方程和本构方程以其微分和速率形式合并，绕过了增量实现的要求。这简化了pin的应用，以解决复杂的机械问题，特别是那些涉及梯度增强连续体的问题。此外，不再需要传统的网格划分，因为它被点云所取代，使得克服网格划分的缺点成为可能。研究结果证明了所提出方法的有效性，特别是在非单调加载条件和不可逆塑性变形方面。与经典有限元方法相比，本文提出的时空pin更容易应用于以原始形式处理的复杂问题。对于梯度增强连续体问题尤其如此，因为在经典有限元方法中不需要引入额外的自由度。然而，pinn训练通常需要更多的计算时间，这一挑战可以通过采用迁移学习的概念来缓解，如本文所示。这个概念在进行参数化研究时非常有用，它涉及到将解决一个问题的知识粒度应用到另一个不同但相关的问题。在即将到来的时代，使用pin作为机械求解器被证明是非常有前途的，GPU技术的进步可以进一步提高它们在计算时间方面的性能。

Oligo-cyclic Loading-induced Evolution of Stress Distribution and Apparent Amorphous Modulus in Lamellar Stacks of High-density Polyethylene

Hang GUO, Renaud G. RINALDI, Sourour TAYAKOUT, Morgane BROUDIN, Olivier LAME

doi:10.1016/j.mechmat.2024.105137

低循环加载诱导高密度聚乙烯片层堆应力分布和表观非晶态模量的演化

Assessing the resistance of high-density polyethylene (HDPE) against earthquake-like loads involves understanding the changes in structure and properties induced by oligo-cyclic loading at various length scales. To study the evolution of stress distribution and intrinsic properties within lamellar stacks from pristine to oligo-cyclic loading pre-conditioned materials, simultaneous in-situ SAXS/WAXS measurements were performed. During the elastic deformation of each pristine and preconditioned sample, crystal strain was tracked using the in-situ WAXS technique. Based on the established elastic tensor of the crystalline structure in polyethylene, we calculated the microscopic stress values within crystalline lamellae. In the pristine sample, lamellar stacks exhibit closely series-like coupling in the equatorial region and parallel-like coupling in the polar region of the spherulite. In the pre-conditioned sample, stress is primarily concentrated in the intra-fibrillar region, where the crystalline and amorphous phases are series-coupled, and strong strain concentration occurs in the inter-fibrillar region. By combining the local strain in the amorphous layer within the lamellar stacks in the equatorial region of the spherulite and the intra-fibrillar region with series-coupled lamellar stacks, measured by in-situ SAXS tests, the apparent amorphous modulus at the lamellar stack scale can be determined. This modulus changes from 71-106 MPa in the equatorial region of pristine spherulites to a notable 2000-7000 MPa in the intra-fibrillar region under the influence of oligo-cyclic pre-loading. Importantly, this apparent modulus is affected by both crystallization conditions and molecular structure, with molecular parameters exerting the primary influence.

评估高密度聚乙烯(HDPE)对类地震载荷的抵抗能力需要了解不同长度尺度的低循环载荷引起的结构和性能变化。为了研究从原始到低循环加载预处理材料层状叠层内应力分布和本征特性的演变，同时进行了原位SAXS/WAXS测量。在每个原始和预处理样品的弹性变形过程中，使用原位WAXS技术跟踪晶体应变。基于已建立的聚乙烯晶体结构弹性张量，计算了晶体片层内的微观应力值。在原始样品中，层状叠层在球晶的赤道区表现出紧密的串联耦合，在极区表现出平行耦合。在预处理后的样品中，应力主要集中在纤维内区，其中晶相和非晶相串联耦合，并且在纤维间区发生强烈的应变集中。通过原位SAXS测试，结合球晶赤道区和串联片层叠层内非晶态层的局部应变，可以确定片层叠层尺度下的表观非晶态模量。在低循环预加载的影响下，原始球晶赤道区域的模量从71 ~ 106 MPa变化到纤维内区域的2000 ~ 7000 MPa。重要的是，这种表观模量受结晶条件和分子结构的影响，其中分子参数起主要作用。

Planar metamaterial with sign-switching Poisson’s ratio based on self-contact slits

Ying Gao, Qingxu Liu, Yuntong Du, Xingyu Wei, Hong Hu, Zhengong Zhou, Jian Xiong

doi:10.1016/j.mechmat.2024.105138

基于自接触狭缝的符号开关泊松比平面超材料

The emergence of artificial metamaterials not only enables many physical and mechanical properties that are not accessible by natural materials but also provides people with new opportunities to break down particular limitations in engineering. In this work, a new metamaterial characterized by unusual sign-switching Poisson’s ratio is introduced. Different from all conventional and auxetic materials that exhibit reversed lateral deformation under tension and compression, the new metamaterial proposed here always expands in the direction orthogonal to the applied load. Our design relies on a planar construction perforated with periodically distributed self-contact slits. The mechanical responses of the proposed metamaterial subjected to uniaxially tensile, compressive, and bending loads are systematically investigated using a combination of numerical simulations and experimental tests. It is found that a lateral expansion effect is also induced for the bending test. Based on its unique property, a new concept of implant is developed to reduce the risk of loosening after total hip replacement. The demonstrative example highlights the potential applications of the new metamaterial in various fastening systems.

人工超材料的出现不仅使人们获得了许多天然材料无法获得的物理和机械性能，而且为人们打破工程上的特定限制提供了新的机会。本文介绍了一种具有异常符号切换泊松比的新型超材料。与所有常规材料和塑性材料在拉伸和压缩下表现出反向侧向变形不同，本文提出的新型超材料总是在与施加载荷正交的方向上膨胀。我们的设计依赖于一个平面结构，穿孔与周期性分布的自接触狭缝。采用数值模拟和实验测试相结合的方法，系统地研究了所提出的超材料在单轴拉伸、压缩和弯曲载荷下的力学响应。发现在弯曲试验中还会产生横向膨胀效应。基于其独特的性能，开发了一种新的植入物概念，以降低全髋关节置换术后松动的风险。该示范实例突出了新型超材料在各种紧固系统中的潜在应用。

Hierarchical elastoplasticity of cortical bone: Observations, mathematical modeling, validation

Valentina Kumbolder, Claire Morin, Stefan Scheiner, Christian Hellmich

doi:10.1016/j.mechmat.2024.105140

皮质骨的分层弹塑性:观察，数学建模，验证

Motivated by the water layer-coated nanoscale bone mineral crystals and the elastoplastic behavior seen at the extracellular scale, we develop a six-step hierarchical micromechanics model for the elastoplasticity of cortical bone. For that purpose, the Eshelby problem-based concentration-influence tensor concept is generalized for a multi-scale situation, quantifying the mechanical interaction between elastic and plastic strains between material phases across six orders of magnitude in observation scale. This hierarchical interaction scheme is complemented by non-associated Mohr–Coulomb plasticity assigned to the mineral crystal phases, and a return mapping algorithm which adapts classical computational mechanics approaches for the realm of semi-analytical continuum micromechanics. Founded on elastic and strength properties of molecular collagen and hydroxyapatite, the model passes experimental validation against ultrasonic and quasi-static tests at the extrafibrillar, extracellular, extravascular, and cortical observation scales, across different tissue and species. It reveals cortical bone strength to increase nonlinearly with the vascular porosity, and to depend bi-linearly on the extracellular mass density, while elucidating plastic spreading events at the nanocrystal scale, which are fundamentally different in tensile and compressive loading.

受水层包覆的纳米级骨矿物晶体和细胞外尺度的弹塑性行为的驱动，我们开发了一个六步层次微观力学模型来研究皮质骨的弹塑性。为此，将基于Eshelby问题的浓度影响张量概念推广到多尺度，在观测尺度上量化六个数量级的材料相间弹塑性应变之间的力学相互作用。这种分层相互作用方案由分配给矿物晶体相的非关联莫尔-库仑塑性和一种适用于半解析连续体微力学领域的经典计算力学方法的返回映射算法加以补充。该模型以分子胶原蛋白和羟基磷灰石的弹性和强度特性为基础，在不同组织和物种的纤维外、细胞外、血管外和皮质观察尺度上通过了超声和准静态测试的实验验证。它揭示了皮质骨强度与血管孔隙度呈非线性增长，并与细胞外质量密度呈双线性增长，同时阐明了纳米晶体尺度上的塑性扩散事件，这在拉伸和压缩载荷下是根本不同的。

A novel three dimensional failure criterion for quasi-brittle materials based on multi-scale damage approach

Lu Ren, Zhao-Min Lv, Fu-Jun Niu, Zi-Peng Qin, Lun-Yang Zhao

doi:10.1016/j.mechmat.2024.105142

基于多尺度损伤方法的准脆性材料三维破坏准则

In this paper, we propose a novel three-dimensional micromechanics-based failure criterion to assess the load-bearing capacity of quasi-brittle materials under complex multiaxial stress conditions. This criterion not only inherits benefits of the multi-scale friction-damage coupling modeling approach but also accounts for the effect of the intermediate principal stress. Physically, the initiation and propagation of microcracks contribute to the damage, and the failure of the material ultimately occurs due to the unstable growth of microcracks. Simultaneously, plastic deformation, which results from frictional sliding along microcracks, is intimately coupled with the damage process. Employing friction-damage coupling up-scale analyses and introducing a novel parabolic local frictional law, we derive a new nonlinear compression meridian criterion within the upscaling framework. Moreover, by incorporating a Lode dependence function, this criterion effectively addresses variations in strength induced by the intermediate principal stress. To validate this criterion, we utilize data from triaxial compression, triaxial extension, and true triaxial tests conducted on various rock materials and concrete, all of which demonstrate excellent agreement.

本文提出了一种新的基于三维细观力学的准脆性材料在复杂多轴应力条件下的承载能力评估准则。该准则不仅继承了多尺度摩擦损伤耦合建模方法的优点，而且考虑了中间主应力的影响。从物理上讲，微裂纹的萌生和扩展是造成损伤的原因之一，而材料的破坏最终是由于微裂纹的不稳定扩展而发生的。同时，由微裂纹摩擦滑动引起的塑性变形与损伤过程密切相关。利用摩擦损伤耦合的上尺度分析，引入新的抛物型局部摩擦律，在上尺度框架内推导出新的非线性压缩子午线准则。此外，通过纳入矿脉依赖函数，该准则有效地解决了由中间主应力引起的强度变化。为了验证这一标准，我们利用了在各种岩石材料和混凝土上进行的三轴压缩、三轴拉伸和真三轴试验的数据，所有这些都证明了非常好的一致性。

International Journal of Plasticity

An anisotropic damage visco-hyperelastic model for multiaxial stress-strain response and energy dissipation in filled rubber

Lionel Ogouari, Qiang Guo, Fahmi Zaïri, Thanh-Tam Mai, Kenji Urayama

doi:10.1016/j.ijplas.2024.104111

填充橡胶多轴应力-应变响应及能量耗散的各向异性损伤粘-超弹性模型

In this article, we introduce a novel physically-based anisotropic damage visco-hyperelastic model designed to predict the history-dependent inelastic behavior of multiaxially stretched filled rubber. The model integrates both the anisotropic Mullins effect and intrinsic viscosity through the consideration of internal physics, represented by two distinct networks: an elastic ground network and a superimposed viscous network. The rupture of molecular bonds within the elastic network chain backbone is modeled using statistical mechanics, while the effects of anisotropy-induced chain orientation at the upper scale are addressed through a microsphere-based scale transition method. The intrinsic viscosity is represented by the viscous network, which is governed by time-dependent equations to account for the viscous overstress. The influence of fillers is captured through the concept of strain amplification, applied to the two networks within the rubber matrix. The effectiveness of the model in capturing the biaxial behavior of filled rubber is evaluated by comparing its outputs with experimental data from a filled rubber system. This assessment specifically considers the impact of pre-stretching under various loading conditions and across a wide range of filler concentrations. Notably, it successfully predicts anisotropic stress-strain response and energy dissipation, and the coupled effects of damage and viscosity.

本文介绍了一种新的基于物理的各向异性损伤粘弹性模型，用于预测多轴拉伸填充橡胶的历史非弹性行为。该模型通过考虑内部物理特性，将各向异性Mullins效应和本征黏度结合在一起，由两个不同的网络表示:弹性地面网络和叠加粘性网络。采用统计力学方法对弹性网络链主链内分子键断裂进行了建模，并通过基于微球的尺度转换方法解决了各向异性诱导链取向在上尺度上的影响。本征粘度由粘性网络表示，该网络由时变方程控制，以解释粘性超应力。通过应变放大的概念捕捉填料的影响，应用于橡胶基体内的两个网络。通过将该模型的输出与填充橡胶系统的实验数据进行比较，评估了该模型在捕获填充橡胶双轴行为方面的有效性。该评估特别考虑了在各种加载条件下和填料浓度范围内预拉伸的影响。值得注意的是，它成功地预测了各向异性应力应变响应和能量耗散，以及损伤和粘度的耦合效应。

Thin-Walled Structures

Effect of orbital hybridization inspired tessellation strategy on the mechanical properties of lattice structures

Mohit Sood, Chang Mou Wu, Chih Wei Tang

doi:10.1016/j.tws.2024.112396

轨道杂化激发镶嵌策略对晶格结构力学性能的影响

The work presents a noble orbital hybridization-inspired tessellation approach for lattice structures, which may modify the characteristics of a lattice. The strategy organizing lattice unit cells according to sp, sp2, sp3, and sp3d2 hybridization patterns. Material extrusion (MEX) was employed to manufacture the tessellated structures, and it was investigated using static and dynamic loads. The sp3-inspired tessellation displayed the greatest energy absorption and revealed two separate failure modes: layer-wise and layer-coupled cell failure. The sp3-inspired tessellated structure displayed the greatest modulus and plateau stress. The current approach was effectively employed to modify the static and dynamic mechanical characteristics of lattice unit cells.

这项工作提出了一种崇高轨道杂化启发的点阵结构镶嵌方法，它可以改变点阵的特性。根据sp, sp2, sp3和sp3d2杂交模式组织晶格单元格的策略。采用材料挤压法(MEX)制造了这种镶嵌结构，并对其进行了静、动载荷研究。sp3激发的镶嵌显示出最大的能量吸收，并显示出两种不同的失效模式:层式和层耦合细胞失效。sp3激发的镶嵌结构表现出最大的模量和平台应力。目前的方法可以有效地修改晶格单元胞的静态和动态力学特性。

Experimental and Numerical Studies on Corrugated Steel Retrofitted Damaged Reinforced Concrete Arches

Zhan Yu, Faqi Liu, Changyong Liu, Hua Yang, Yuyin Wang, Yiming Pei

doi:10.1016/j.tws.2024.112386

受损钢筋混凝土拱的波纹钢加固试验与数值研究

The corrugated steel (CS) reinforcement method has been adopted for strengthening dilapidated bridges and culverts owing to its advantages of convenient construction, good corrosion resistance, and high deformability. However, the current design method for corrugated steel retrofitted damaged reinforced concrete (CSRDRC) arches is excessively conservative as it only considers the bearing capacity of the CS, neglecting the contributions of the original reinforced concrete (RC) structure and the infill layer. This paper studied the behaviour of CSRDRC arches under three-point loading experimentally and numerically. The experimental results demonstrate that the bearing capacity and initial stiffness of the arches are significantly enhanced after CS reinforcement. The increase in damage degree of the original structure has a slight effect on the bearing capacity and initial stiffness, but an obvious adverse effect on the ductility of the CSRDRC arches. A finite element model (FEM) was developed and verified against test results and then utilized to conduct parametric analysis. Finally, a simplified formula was proposed for predicting the axial compressive bearing capacity of CSRDRC arches.

波纹钢加固法因其施工方便、耐腐蚀性能好、变形能力强等优点，被广泛应用于危房桥涵加固。然而，目前的波纹钢改造受损钢筋混凝土(CSRDRC)拱的设计方法过于保守，只考虑CS的承载力，而忽略了原钢筋混凝土(RC)结构和填充层的贡献。本文对CSRDRC拱在三点荷载作用下的受力特性进行了试验和数值研究。试验结果表明，CS加固后拱的承载力和初始刚度均有显著提高。原结构损伤程度的增加对CSRDRC拱的承载力和初始刚度影响较小，但对其延性影响明显。建立了有限元模型，并根据试验结果进行了验证，然后利用有限元模型进行了参数分析。最后，提出了CSRDRC拱轴压承载力的简化预测公式。

Unilateral buckling of thin plates by complementarity eigenvalue analyses

J.M. Figueiredo, F.M.F. Simões, A. Pinto da Costa

doi:10.1016/j.tws.2024.112387

薄板单边屈曲的互补特征值分析

In this work, the analysis by the finite element method of thin plates subjected to buckling in the presence of unilateral punctual obstacles, that is, supports that allow the plate to move in one direction but prevent the motion in the opposite direction, is addressed. An appropriate algorithm based on the solution of a semi-smooth system of equations, that results from the formulation of the unilateral buckling problem as a complementarity eigenvalue problem, is used. Rectangular and square plates are analysed under various membrane loadings, including compression and shear. The conformal Bogner–Fox–Schmit (BFS) finite element is employed to compute the bifurcation loads and the corresponding instability modes in scenarios with and without unilateral obstacles. For each plate and type of loading, the six lowest bifurcation loads and corresponding modes are computed for different levels of mesh refinement. The results confirm that the convergence of bifurcation loads obtained using the BFS element is monotonically decreasing as the mesh is refined. It is also confirmed that, when unilateral obstacles are present, the lowest bifurcation load, known as the critical load, can never be lower than the one of the homologous problem without unilateral obstacles.

在这项工作中，用有限元方法分析了薄板在存在单边准时障碍物(即允许板在一个方向上移动但阻止在相反方向上移动的支撑)的情况下遭受屈曲的薄板。将单侧屈曲问题转化为互补特征值问题，采用了一种基于半光滑方程组解的适当算法。矩形和方形板在各种膜荷载下进行了分析，包括压缩和剪切。采用保形Bogner-Fox-Schmit (BFS)有限元计算了有和无单边障碍物情况下的分岔载荷及其失稳模态。针对每种板和荷载类型，计算了不同网格细化水平下的6种最低分岔荷载及其对应的模态。结果表明，随着网格的细化，BFS单元得到的分岔载荷收敛性呈单调递减趋势。当存在单侧障碍时，最小分岔荷载(即临界荷载)不可能低于无单侧障碍的同类问题的分岔荷载。

Recovery resilience framework of replaceable AB-BRB for seismic strengthening during the aftershock stage

Xu-Yang Cao, Dejian Shen, Kun Ji, Zhe Qu, Chun-Lin Wang

doi:10.1016/j.tws.2024.112389

可替换AB-BRB在余震阶段抗震加固中的恢复弹性框架

Earthquakes cause serious damage to structures, and seismic strengthening is an effective solution to improving structural capacity. With the development of prefabricated technology, the assembled buckling-restrained braces (BRBs) have garnered significant attention in structural engineering due to their potentials to enhance seismic resilience and to guarantee recoverability behavior. At this stage, research on the replaceable performance of assembled BRBs is limited in the current body of literature. The specific focus on the replaceability aspect of assembled BRBs, including the ease of replacing individual components or the entire brace system, has not been extensively explored. Meanwhile, research on earthquake resilience during the aftershock stage is relatively limited at present. Despite the recognition of the significant and prolonged impact of aftershocks on communities and infrastructure, there is a paucity of comprehensive studies specifically focusing on the resilience strategies and measures required during this stage. The authors formerly proposed a novel assembled bolt-connected BRB (AB-BRB), and experiments have been conducted to verify its hysteretic and replaceable behaviors. In this paper, the recovery resilience of the proposed replaceable AB-BRB for seismic strengthening is further assessed, especially during the aftershock stage. The replacement realization of AB-BRB in analysis is first introduced. Then the recovery resilience framework for assessment during the aftershock stage is proposed. Finally an implementary example is given to perform the recovery resilience framework, in which two cases and three scenarios are discussed in detail. In general, after using the AB-BRB for seismic strengthening, the recovery time obviously decreases and the resilience index obviously increases when compared with the results in un-strengthened scenario (scenario 3), which demonstrates that the retrofitted system possesses a better resilience recovery capacity. For EEL in case 1, the recovery days are given to be 298.7446 before strengthening (scenario 3), and the results drop to 165.4133 (scenario 1) and 147.0295 (scenario 2) after strengthening. Correspondingly, the resilience index is calculated as 0.5022 before strengthening (scenario 3), and the results increase to 0.7101 (scenario 1) and 0.7411 (scenario 2) after strengthening. Similar conclusions can be given for case 2 and other intensity levels. Meanwhile, after performing the replacement operation of AB-BRB (scenario 2), the seismic performance of the retrofitted system further enhances during the aftershock stage (i.e., less recovery days and larger resilience index). For case 1 and recovery form 1, the resilience index for 1 month is signified as 0.6272, 0.6869 and 0.2066 from scenario 1 to 3, and the resilience index for 3 months is signified as 0.8182, 0.8561 and 0.4965 from scenario 1 to 3. Compared with scenario 1, the recovery ability in scenario 2 is further ensured and the potential risk is further controlled, which demonstrates the importance of replaceable capacity of AB-BRB for resilience improvement especially during the aftershock stage.

地震对结构造成严重破坏，抗震加固是提高结构承载力的有效手段。随着预制技术的发展，装配式抗屈曲支撑(brb)因其具有提高抗震性能和保证恢复性能的潜力而在结构工程中受到了广泛的关注。在这个阶段，对组装brb的可替换性能的研究在目前的文献中是有限的。具体关注组装brb的可替换性方面，包括更换单个组件或整个支架系统的便利性，尚未得到广泛探索。同时，目前对余震阶段的地震恢复力研究相对有限。尽管认识到余震对社区和基础设施的重大和长期影响，但缺乏专门关注这一阶段所需的恢复力战略和措施的全面研究。作者提出了一种新型组合螺栓连接BRB (AB-BRB)，并通过实验验证了其滞回性和可替换性。本文进一步评估了所提出的可替代AB-BRB用于地震加固的恢复弹性，特别是在余震阶段。首先介绍了AB-BRB在分析中的替代实现。在此基础上，提出了余震阶段的恢复弹性评估框架。最后给出了恢复弹性框架的实现实例，详细讨论了两种情况和三种场景。总体而言，与未加固情景(情景3)相比，采用AB-BRB加固后的恢复时间明显缩短，恢复指数明显提高，说明加固后的体系具有更好的恢复能力。对于情景1的EEL，强化前(情景3)的恢复天数为298.7446，强化后的恢复天数分别为165.4133(情景1)和147.0295(情景2)。相应的，加固前(场景3)的弹性指数计算值为0.5022，加固后的结果分别增加到0.7101(场景1)和0.7411(场景2)。病例2和其他强度水平也可以得出类似的结论。同时，在对AB-BRB进行替换操作(场景2)后，改造后的体系在余震阶段的抗震性能进一步提高(即恢复天数更少，弹性指数更大)。对于案例1和恢复形式1，情景1 - 3的1个月弹性指数分别为0.6272、0.6869和0.2066，情景1 - 3的3个月弹性指数分别为0.8182、0.8561和0.4965。与情景1相比，情景2的恢复能力得到了进一步的保证，潜在风险得到了进一步的控制，说明了AB-BRB的可替代能力对于提高抗灾能力的重要性，特别是在余震阶段。

Influence of bionic texture on the mechanical properties of 6061Al/CFRTP laser joints

Jingcheng Li, Yixuan Zhao, Xueyan Zhang, Jianhui Su, Caiwang Tan, Jin Yang, Xiaoguo Song, Wei Song, Guanghui Guo

doi:10.1016/j.tws.2024.112393

仿生织构对6061Al/CFRTP激光接头力学性能的影响

Joining carbon fiber reinforced thermoplastic composites (CFRTP) with metals is a significant challenge for lightweighting in the automotive sector. The lower strength of hybrid joints limits their applications in the relevant fields. In this study, three distinct surface textures were applied to 6061 aluminum alloy (6061Al), including a traditional groove texture and two novel bionic textures (shark skin and fish scale), to enhance the strength of the hybrid joint between the materials. The impact of these textures on the mechanical properties of 6061Al/CFRTP hybrid joints was investigated through experimental methods and finite element simulations. The results indicated that the stress distribution at the interface of the bionic textured samples was more uniform, reducing stress concentration at the interface. Furthermore, the hybrid joint strength was improved as the bionic texture hindered crack initiation and propagation and facilitated crack deflection. Compared to the untextured samples, the fish scale textured samples exhibited the highest strength, which increased by 431.3 % relative to the untextured samples.

将碳纤维增强热塑性复合材料(CFRTP)与金属结合是汽车行业轻量化的重大挑战。混合接头强度较低，限制了其在相关领域的应用。本研究将三种不同的表面纹理应用于6061铝合金(6061Al)，包括传统的凹槽纹理和两种新颖的仿生纹理(鲨鱼皮和鱼鳞)，以提高材料之间混合连接的强度。通过实验方法和有限元模拟研究了这些织构对6061Al/CFRTP复合接头力学性能的影响。结果表明:仿生织构试样的界面应力分布更加均匀，界面应力集中程度降低;仿生织构阻碍了裂纹的萌生和扩展，促进了裂纹的挠曲，从而提高了杂化接头的强度。鱼鳞纹理样品的强度最高，比未纹理样品提高了431.3%。