今日更新:Journal of the Mechanics and Physics of Solids 1 篇,Mechanics of Materials 1 篇,Thin-Walled Structures 4 篇
Propagation of solitary waves in origami-inspired metamaterials
Quan Zhang, Stephan Rudykh
doi:10.1016/j.jmps.2024.105626
孤波在折纸启发超材料中的传播
We propose a design strategy for creating origami-like mechanical metamaterials with diverse non-linear mechanical properties and capable of remote actuation. The proposed triangulated cylindrical origami (TCO)-inspired metamaterials enable the highly desirable strain-softening/hardening and snap-through behaviors via a multi-material and highly deformable hinge design. Moreover, we couple these novel non-linear mechanical properties of the TCO origami-inspired metamaterials with the transformative ability of hard-magnetic active materials, allowing for untethered shape- and property-actuation in the developed metamaterials. We develop a mathematical modeling framework for the proposed TCO origami-inspired metamaterials, building on approximating the highly deformable hinges as a combination of longitudinal and rotational springs. We validate the accuracy of the developed mathematical modeling approach by comparing the analytically predicted compressive response of a unit cell structure with the corresponding numerical and experimental results. Using the developed mathematical modeling framework, we investigate the magnetic field-induced large deformation and superimposed solitary wave propagation in the TCO origami-inspired metamaterial system. We show that the proposed metamaterial allows us to tune the key characteristics of the enabled non-linear solitary waves, including their characteristic width and amplitude. The proposed design strategy for readily manufacturable origami-inspired metamaterial systems paves a novel path for practical engineering applications. Our studies also underscore the potential of magneto-mechanical interaction in the design of reconfigurable metamaterial systems with superior non-linear mechanical and elastic wave properties.
我们提出了一种设计策略,用于制造具有多种非线性机械特性并能够远程驱动的类似折纸的机械超材料。受三角圆柱折纸(TCO)启发而提出的超材料通过多材料和高变形铰链设计,实现了非常理想的应变软化/硬化和卡穿行为。此外,我们还将 TCO 折纸启发超材料的这些新型非线性机械特性与硬磁性活性材料的转换能力结合起来,使所开发的超材料能够实现无束缚的形状和特性致动。我们在将高变形铰链近似为纵向弹簧和旋转弹簧组合的基础上,为拟议的 TCO 起源启发超材料开发了一个数学建模框架。我们通过比较单元结构的分析预测压缩响应与相应的数值和实验结果,验证了所开发的数学建模方法的准确性。利用所开发的数学建模框架,我们研究了磁场诱导的大变形和叠加孤波在 TCO 起源启发超材料系统中的传播。我们的研究表明,所提出的超材料允许我们调整所启用的非线性孤波的关键特性,包括其特征宽度和振幅。针对可随时制造的折纸启发超材料系统提出的设计策略为实际工程应用铺平了一条新路。我们的研究还强调了磁-机械相互作用在设计具有卓越非线性机械波和弹性波特性的可重构超材料系统方面的潜力。
The interfacial behavior of an axisymmetric film bonded to a graded inhomogeneous substrate
Dengke Li, Peijian Chen, Hao Liu, Zhilong Peng, Mehmet Ali Guler, Shaohua Chen
doi:10.1016/j.mechmat.2024.104983
轴对称薄膜与渐变不均匀基底的界面行为
With the development of high-tech applications such as thermal barrier coatings, stretchable and flexible electronics, etc, the key film/substrate systems are more commonly involving three-dimensional axisymmetric problems with graded inhomogeneous substrates. In these film/substrate systems, the effects of geometric and material factors of both the films and the substrates on the interfacial behavior are urgently needed to be uncovered. Herein, a novel theoretical axisymmetric model of an elastic film bonded to a graded substrate is proposed and solved by using Hankel integral transformation and orthotropic polynomials. The interfacial shear stress and the corresponding shear stress intensity factor as well as radial stresses and hoop stresses of both the film and the graded substrate are obtained. It is found that the present model works well to predict the interfacial behavior between an axisymmetric film and a graded substrate. Compared with cases with homogeneous substrates, choosing graded substrates can reduce the risk of edge fracture on the surface of the substrate. A film with a smaller elastic modulus and thickness is advantageous for the interface reliability of the film/substrate system under a thermal load. The results should be useful for not only understanding the load transfer mechanism of axisymmetric film/substrate system, but also providing a valuable guidance to optimize film/substrate structures in various practical and potential applications.
随着热障涂层、可拉伸和柔性电子器件等高科技应用的发展,关键的薄膜/基底系统越来越多地涉及具有梯度不均匀基底的三维轴对称问题。在这些薄膜/基底体系中,迫切需要揭示薄膜和基底的几何和材料因素对界面行为的影响。本文提出了一种新的弹性薄膜与分级基底粘合的轴对称理论模型,并利用汉克尔积分变换和正交多项式进行了求解。得到了界面剪应力和相应的剪应力强度因子,以及薄膜和分级基底的径向应力和箍应力。研究发现,本模型能很好地预测轴对称薄膜和分级基底之间的界面行为。与均匀基底的情况相比,选择分级基底可以降低基底表面边缘断裂的风险。弹性模量和厚度较小的薄膜有利于薄膜/基底系统在热负荷下的界面可靠性。研究结果不仅有助于理解轴对称薄膜/基底系统的载荷传递机理,还为优化薄膜/基底结构在各种实际和潜在应用中提供了宝贵的指导。
Development and validation analysis of a steel-lead hybrid dual-yield BRB for multi-stage seismic energy dissipation
Mingming Jia, Yinzhen Chen, Peisi Jin
doi:10.1016/j.tws.2024.111822
用于多级地震消能的钢铅混合双屈服 BRB 的开发和验证分析
To address the limitations inherent in conventional all-steel buckling restrained braces (BRBs) that maintain elastic behavior and lack seismic energy dissipation during frequent earthquakes (FEs), this study proposes a novel approach of combining lead dampers with BRB, forming the development of steel-lead hybrid dual-yield BRB (or simply dual-yield BRB). Integrating lead material into the dual-yield BRB harnesses its dynamic recrystallization capacity, allowing the lead dampers to yield and efficiently dissipate seismic energy during FEs via well-designed configurations. This study delineates the approach for connecting lead dampers to BRBs and performs comparative quasi-static tests on dual-yield BRBs and conventional BRBs. Key observations from the laboratory tests confirmed that lead dampers experience earlier failure compared to inner cores. Dual-yield BRB exhibited significantly lower initial displacement requirements for energy dissipation than conventional BRB, demonstrating a hexagonal hysteretic curve, trilinear behavior in the skeleton curve, and superior overall energy dissipation capacity at small displacements. The feasible strategy of refined numerical simulations was initially validated based on experimental results. Subsequently, to enhance analysis efficiency, simplified models using truss elements were developed and endorsed. Elasto-plastic time history analyses were performed on benchmark models of 9-story steel frames, considering scenarios with no bracing, conventional BRBs, and dual-yield BRBs, exposed to FEs and maximum considered earthquakes (MCEs). Various parameters, including component forces, structural displacement and damping underwent thorough examination. These findings underscore the exceptional seismic performance and energy dissipation abilities of dual-yield BRBs, solidifying them as a valuable addition to earthquake-resistant structural systems.
传统的全钢屈曲约束支撑(BRBs)在频繁地震(FEs)中只能保持弹性行为而缺乏地震能量耗散,为了解决这种固有的局限性,本研究提出了一种将铅阻尼器与 BRB 结合的新方法,形成了钢铅混合双屈服 BRB(或简称双屈服 BRB)。将铅材料集成到双屈服 BRB 中可利用其动态再结晶能力,使铅阻尼器在 FE 期间通过精心设计的配置屈服并有效消散地震能量。本研究阐述了将铅阻尼器连接到 BRB 的方法,并对双韧性 BRB 和传统 BRB 进行了准静力对比试验。实验室测试的主要观察结果证实,与内芯相比,铅阻尼器会更早失效。与传统 BRB 相比,双矢量 BRB 在消能方面的初始位移要求明显降低,表现出六边形滞回曲线、骨架曲线的三线性行为,以及在小位移时卓越的整体消能能力。在实验结果的基础上,初步验证了精细数值模拟的可行策略。随后,为提高分析效率,开发并认可了使用桁架元素的简化模型。对 9 层钢架的基准模型进行了弹塑性时间历程分析,考虑了无支撑、传统 BRB 和双屈服 BRB 的情况,并暴露于 FE 和最大考虑地震 (MCE) 中。对各种参数,包括构件力、结构位移和阻尼进行了全面检查。这些发现强调了双屈服 BRB 的卓越抗震性能和消能能力,使其成为抗震结构系统的重要补充。
A model for the temperature-dependent creep/recovery behavior of dry fiber fabric considering in-plane tension
Yanpeng Si, Zhiyong Zhao, Lishuai Sun, Junzhen Chen, Yujun Li, Jianjun Jiang
doi:10.1016/j.tws.2024.111817
考虑平面张力的干纤维织物随温度变化的蠕变/恢复行为模型
In the manufacturing process of fiber-reinforced composite materials, the preforming of dry fiber fabrics is typically carried out under specific out-of-plane pressure, in-plane tension, and at designated temperatures. The fabric exhibits significant time and temperature-dependent permanent deformation as well as creep/recovery behavior. Gaining a better understanding of these phenomena and harnessing predictive capabilities will be instrumental in achieving more precise control over fiber volume fraction and material composition. In this paper, creep/recovery experiments and cyclic loading-unloading tests were conducted on CF3031 dry fiber preforms under various in-plane tensions and temperatures, measuring in-plane strains using Fiber Bragg Grating (FBG) sensors. Based on this data, a modified Burgers viscoelastic-plastic model has been proposed to describe the time-dependent creep/recovery behavior of dry fiber fabric preforming under the coupled effects of in-plane tension, out-of-plane pressure, and temperature variations. This model employs a single set of equations and parameters to represent the complete creep/recovery process of the material. The experimental results align well with the predicted outcomes across different compression scenarios.
在纤维增强复合材料的制造过程中,干纤维织物的预成型通常是在特定的平面外压力、平面内张力和指定温度下进行的。织物会表现出明显的随时间和温度变化的永久变形以及蠕变/恢复行为。更好地了解这些现象并利用预测能力将有助于实现对纤维体积分数和材料成分的更精确控制。本文在各种面内张力和温度条件下对 CF3031 干纤维预型件进行了蠕变/恢复实验和循环加载-卸载测试,并使用光纤布拉格光栅 (FBG) 传感器测量面内应变。根据这些数据,我们提出了一个改进的布尔格斯粘弹塑性模型,用于描述干纤维织物预制件在平面内张力、平面外压力和温度变化的耦合作用下随时间变化的蠕变/恢复行为。该模型采用单组方程和参数来表示材料的整个蠕变/恢复过程。实验结果与不同压缩情况下的预测结果非常吻合。
Approximate closed-form solutions for free vibration of circular arches with discrete lateral braces
Chen Long-Kai, Chen Hai-Jun, Cai Yong
doi:10.1016/j.tws.2024.111820
带离散侧向支撑的圆拱自由振动的近似闭式解法
Discrete lateral braces are commonly employed to enhance the out-of-plane stability of arches. However, these braces generate coupling effects among vibration modes, which significantly impact the vibration characteristics of the arches. This paper presents an analytical solution for the free vibration analysis of two-hinged arches with equally-spaced lateral translational and/or rotational braces. A simplified method of evaluating the fundamental frequency for the out-of-plane vibration of arches with equally-spaced lateral braces is introduced. The method relies on the conventional approach of representing arch braces through elastic springs, but here the out-of-plane deflection of the braced arch is constructed by adding related coupled sinusoidal functions to that of the unbraced arch, satisfying both the boundary and kinematic conditions. Subsequently, the fundamental frequency and threshold bracing stiffness or stiffness requirement are derived using the Rayleigh–Ritz method. Finite element analysis (FEA) is applied to investigate the flexural-torsional vibration mode and fundamental frequency of arches with discrete braces, and the results from FEA closely match the theoretical predictions. The effects of number of lateral translational and/or rotational brace, out-of-plane slenderness, included angle, bracing stiffness and bracing position on the fundamental frequency are comprehensively analyzed. It is found that when the fundamental frequency of the braced arch increases due to changes in bracing stiffness, the mode shape displays more intricate behavior, rather than following a straightforward low-to-high mode growth pattern. Furthermore, it is observed that in some cases, the addition of rotational bracing stiffness can markedly enhance the maximum fundamental frequency of the arch with both translational and rotational braces.
离散侧向支撑通常用于增强拱形结构的平面外稳定性。然而,这些支撑会产生振动模式之间的耦合效应,从而严重影响拱形结构的振动特性。本文提出了一种分析方法,用于分析带有等间距横向平移和/或旋转支撑的双铰接拱的自由振动。本文介绍了一种简化方法,用于评估带有等间距横向支撑的拱门平面外振动的基频。该方法依赖于通过弹性弹簧表示拱形支撑的传统方法,但在这里,支撑拱形的平面外挠度是通过在无支撑拱形的平面外挠度上添加相关耦合正弦函数来构建的,同时满足边界条件和运动条件。随后,利用雷利-里兹法得出基频和阈值支撑刚度或刚度要求。应用有限元分析(FEA)研究了带有离散支撑的拱的挠扭振动模式和基频,有限元分析的结果与理论预测非常吻合。全面分析了横向平移和/或旋转支撑数量、平面外细长度、包含角、支撑刚度和支撑位置对基频的影响。研究发现,当支撑拱的基频因支撑刚度的变化而增加时,模态形状会表现出更复杂的行为,而不是简单的从低到高的模态增长模式。此外,研究还发现,在某些情况下,增加旋转支撑刚度可显著提高具有平移和旋转支撑的拱的最大基频。
Experimental and numerical investigation on residual stress and deformation of welded I-section curved steel beams
Fei Xu, Yun Zhao, Ju Chen, Xu Liu, Yuner Huang
doi:10.1016/j.tws.2024.111821
焊接 I 型截面弯曲钢梁残余应力和变形的实验与数值研究
This paper presents an experimental and numerical investigation on welding-induced residual stresses and deformations of in-plane curved welded I-section steel beams. Two welded curved beams with different curvatures were investigated. After welding the curved beam, the residual deformations were measured by a 3D scanner. The residual stresses were subsequently obtained through a high-precision sectioning method. The effects of curvature on the magnitude and distributions of residual deformations and stresses at the specific sections were analysed with the test results. It was found that the residual deformation gradually increased from the weld region to both ends of the flange plate, and the torsion in the web plate became severe with a decrease in curvature of the curved beam. Moreover, the welding process of the curved beam was simulated using the finite element (FE) method. The developed FE model was validated against the test results, and thereafter, parametric analyses were conducted to assess the influence of welding sequence, welding speed, and curvatures of the curved beam on the welding residual stresses and deformations. The numerical results demonstrated that the residual stresses and deformations were significantly influenced by welding speeds, but the influence from curvature of the curved beam was relatively small. Finally, a reasonable welding sequence, welding speed, and curvature of the curved beams were recommended.
本文介绍了对平面内曲线焊接工字形钢梁的焊接引起的残余应力和变形进行的实验和数值研究。研究了两根不同曲率的焊接弯梁。曲面梁焊接后,残余变形由三维扫描仪测量。残余应力随后通过高精度截面方法获得。测试结果分析了曲率对特定截面上残余变形和应力的大小及分布的影响。结果发现,残余变形从焊接区域到翼缘板的两端逐渐增大,腹板的扭转随着弯曲梁曲率的减小而变得严重。此外,还使用有限元(FE)方法模拟了弯梁的焊接过程。开发的 FE 模型与试验结果进行了验证,随后进行了参数分析,以评估焊接顺序、焊接速度和弯曲梁的曲率对焊接残余应力和变形的影响。数值结果表明,焊接速度对焊接残余应力和变形的影响很大,但曲梁曲率的影响相对较小。最后,推荐了合理的焊接顺序、焊接速度和弯梁曲率。