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【新文速递】2024年7月1日固体力学SCI期刊最新文章

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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 1 篇,Thin-Walled Structures 5 篇

International Journal of Solids and Structures

Numerical modeling of wrinkling modulation in tensegrity-membrane structures

Zigang He, Liang Zhang, Yipeng Ge, Shaofan Li

doi:10.1016/j.ijsolstr.2024.112963

张力整体膜结构皱纹调制的数值建模

Tensegrity-membrane structures are potential to be lightweight gossamer spacecraft (e.g., solar sails, radar antennae, solar module), and the dynamics of deployment has been studied in the past studies where the membranes were usually modeled as a flat panel without wrinkles. However, the attitude control of membrane as well as the flatness are critical to the functionality of gossamer spacecraft. The paper proposes a numerical investigation on the modulation of wrinkling in tensegrity-membrane structures. The kinematic and deformation description is based on the co-rotational finite element method (FEM), while the wrinkling of membrane is modeled by Tension Field Theory (TFT). The numerical method is validated by an illustrative experiment, and then used for a surrogate model-based optimization design, in which clustered actuation is responsible for the attitude control of membrane, while classical actuation accounts for the suppression of wrinkles. An interesting tensegrity-membrane “Sunflower” is presented to show the result of optimization, where “Sunflower” can follow the sunlight angle accurately and freely control the orientation of “corolla” while maintaining its daylighting surface quality. This study provides an effective means for the numerical simulation and optimization design of tensegrity-membrane structures, especially when the attitude and wrinkling of membranes must be considered.

张拉膜结构有可能成为轻量级的索纱航天器(如太阳帆、雷达天线、太阳能模块),在过去的研究中已经对膜的部署动力学进行了研究,通常将膜建模为无褶皱的平板。然而,膜的姿态控制和平整度对绞索航天器的功能至关重要。本文提出了对张弦膜结构中褶皱调制的数值研究。运动学和变形描述基于共旋转有限元法(FEM),而膜的起皱则由张力场理论(TFT)建模。数值方法通过一个说明性实验进行了验证,然后用于基于代理模型的优化设计,其中集群致动负责膜的姿态控制,而经典致动则负责抑制褶皱。优化结果表明,"向日葵 "能准确跟踪阳光照射角度,自由控制 "花冠 "的朝向,同时保持其采光表面质量。这项研究为张拉膜结构的数值模拟和优化设计提供了有效手段,尤其是在必须考虑膜的姿态和皱褶的情况下。


Journal of the Mechanics and Physics of Solids

A Griffith description of fracture for non-monotonic loading with application to fatigue

Subhrangsu Saha, John E. Dolbow, Oscar Lopez-Pamies

doi:10.1016/j.jmps.2024.105754

非单调加载的格里菲斯断裂描述及其在疲劳中的应用

With the fundamental objective of establishing the universality of the Griffith energy competition to describe the growth of large cracks in solids not just under monotonic but under general loading conditions, this paper puts forth a generalization of the classical Griffith energy competition in nominally elastic brittle materials to arbitrary non-monotonic quasistatic loading conditions, which include monotonic and cyclic loadings as special cases. Centered around experimental observations, the idea consists in: ( i ) viewing the critical energy release rate G c not as a material constant but rather as a material function of both space X and time t , ( i i ) one that decreases in value as the loading progresses, this solely within a small region Ω ℓ ( t ) around crack fronts, with the characteristic size ℓ of such a region being material specific, and ( i i i ) with the decrease in value of G c being dependent on the history of the elastic fields in Ω ℓ ( t ) . By construction, the proposed Griffith formulation is able to describe any Paris-law behavior of the growth of large cracks in nominally elastic brittle materials for the limiting case when the loading is cyclic. For the opposite limiting case when the loading is monotonic, the formulation reduces to the classical Griffith formulation. Additional properties of the proposed formulation are illustrated via a parametric analysis and direct comparisons with representative fatigue fracture experiments on a ceramic, mortar, and PMMA.

本文的基本目标是建立格里菲斯能量竞争的普遍性,以描述固体中大裂缝的生长,不仅是在单调加载条件下,而且是在一般加载条件下,提出了名义弹性脆性材料中经典格里菲斯能量竞争的一般化,以适应任意的非单调准静态加载条件,其中包括作为特例的单调加载和循环加载。以实验观察为中心,其思路包括( i i ) 临界能量释放率 G c 并非材料常数,而是空间 X 和时间 t 的材料函数, ( i i i ) 随着加载的进行,其值会逐渐减小,这只发生在裂纹前沿周围的一个小区域 Ω ℓ ( t ) 内,该区域的特征尺寸 ℓ 取决于具体材料,而且 ( i i i ) G c 值的减小取决于 Ω ℓ ( t ) 中弹性场的历史。根据构造,在循环加载的极限情况下,所提出的格里菲斯公式能够描述名义弹性脆性材料中大裂缝生长的任何巴黎定律行为。对于单调加载的相反极限情况,该公式则简化为经典的格里菲斯公式。通过参数分析以及与陶瓷、砂浆和聚甲基丙烯酸甲酯的代表性疲劳断裂实验的直接比较,说明了所提公式的其他特性。


A multi-horizon fully coupled thermo-mechanical peridynamics

Changyi Yang, Fan Zhu, Jidong Zhao

doi:10.1016/j.jmps.2024.105758

多地平线全耦合热机械周流体力学

This paper presents a fully coupled thermo-mechanical peridynamic model for simulating interactive thermo-mechanical material responses and thermally induced fracturing of solids. A temperature-dependent constitutive model and a deformation-dependent heat conduction model are derived for state-based peridynamic formulation. The dispersion relation and truncation error of the state-based peridynamic heat equation are analyzed for the first time. It is found that as non-locality becoming more pronounced, the dissipative rate of heat is reduced, and the truncation error becomes larger. A small horizon can effectively mitigate oscillation while reducing the error in the temperature field. For coupled thermo-mechanical modeling, a novel multi-horizon scheme is introduced where the thermal field is solved with a different horizon than that of the mechanical field. The multi-horizon scheme allows for the implementation of a distinct degree of non-locality for different physical field. Comparing with the constant-horizon scheme, we demonstrate through numerical examples that the multi-horizon scheme offers smoother and more accurate solutions and serves a promising option for peridynamics-based multi-physics simulations.

本文提出了一种完全耦合的热-机械围动力学模型,用于模拟交互式热-机械材料响应和固体的热诱导断裂。在基于状态的周动力学计算中,推导出了一个与温度相关的构成模型和一个与变形相关的热传导模型。首次分析了基于状态的周动态热方程的分散关系和截断误差。结果发现,随着非局部性的增强,热的耗散率降低,截断误差变大。小的水平线可以有效缓解振荡,同时减少温度场的误差。在热力-机械耦合建模中,引入了一种新颖的多视界方案,即热力场的求解视界与机械场的不同。多视界方案允许对不同的物理场实施不同程度的非局部性。与恒定视界方案相比,我们通过数值示例证明,多视界方案提供了更平滑、更精确的解决方案,是基于周动力学的多物理场模拟的理想选择。


Mechanics of Materials

Conical indentation over a transversely isotropic and layered elastic half-space

Zhijie Jin, Ernian Pan, Zhiqing Zhang, Kaifu Liu

doi:10.1016/j.mechmat.2024.105081

横向各向同性分层弹性半空间上的锥形压痕

We propose a novel method for solving the static response of a conical indenter on a transversely isotropic and layered elastic half-space. The newly developed Fourier-Bessel series (FBS) system of vector functions, along with the unconditionally stable dual-variable and position method, is employed to derive the Green’s function in the transversely isotropic and layered elastic half-space under a vertical ring load on the surface. To calculate the response at different field points on the surface, we apply discrete love numbers within the FBS vector system. The load densities in the discretized rings within the contact radius of the conical indenter are determined using the integral least-squares method, along with a self-adaptive algorithm developed in this study. Finally, the relationship between the indentation depth (vertical displacement) and the applied load is obtained through force balance between the external load and the summed contact traction. The developed scheme is validated using existing exact solutions for the reduced homogeneous half-space case. Selected numerical results clearly demonstrate the effect of anisotropic material and layering on the indentation response. It is observed that, regardless of whether the structure is a stratified half-space or a layered structure with a rigid substrate, the material properties in the top layer have the most significant influence on the indentation behavior. In the case of a layered structure with an underlying elastic half-space, the material properties in the interlayer and bottom layer could also affect the indentation behaviors.

我们提出了一种新方法,用于求解锥形压头在横向各向同性分层弹性半空间上的静态响应。我们采用新开发的傅里叶-贝塞尔序列(FBS)矢量函数系统以及无条件稳定的双变量和位置法,推导了在表面垂直环载荷作用下横向各向同性分层弹性半空间中的格林函数。为了计算表面上不同场点的响应,我们在 FBS 向量系统中应用了离散爱数。锥形压头接触半径内离散环的载荷密度采用积分最小二乘法和本研究开发的自适应算法确定。最后,通过外部载荷与总接触牵引力之间的力平衡,得出压痕深度(垂直位移)与施加载荷之间的关系。利用现有的精确解法对所开发的方案进行了验证,该方案适用于缩小的均质半空间情况。选定的数值结果清楚地表明了各向异性材料和分层对压痕响应的影响。据观察,无论结构是分层的半空间还是具有刚性基底的分层结构,顶层的材料特性对压痕行为的影响最大。在底层为弹性半空间的分层结构中,层间和底层的材料特性也会影响压痕行为。


Thin-Walled Structures

Efficient Reliability-based Concurrent Topology Optimization Method under PID-driven Sequential Decoupling Framework

Zeshang Li, Lei Wang, Kaixuan Gu

doi:10.1016/j.tws.2024.112117

PID 驱动的顺序解耦框架下基于可靠性的高效并发拓扑优化方法

The continuous improvement of advanced equipment performance has promoted the development of detailed structural design. The detailed design of the structure should meet many requirements such as high reliability, strong robustness, lightweight, and high efficiency. This paper proposes a proportional-integral-derivative-driven efficient reliability-based concurrent topology optimization strategy under the sequential framework. Considering the uncertainty of load position, load direction, load amplitude, and material properties, an efficient reliability-based concurrent topology optimization model is constructed based on the sequential strategy. Based on effectively quantifying the nonlinear characteristics brought by multi-source uncertainty, a constraint refinement movement strategy based on the proportional-integral-derivative controller is proposed, which to some extent overcomes the tedious calculation of uncertainty quantification. This paper provides sensitivity information on macroscopic and microscopic level set functions under displacement constraints. Four numerical examples demonstrate the effectiveness, efficiency, and generalization ability of the proposed method.

先进设备性能的不断提高促进了结构详细设计的发展。结构的详细设计应满足高可靠性、强鲁棒性、轻量化和高效率等诸多要求。本文在顺序框架下提出了一种基于比例-积分-派生驱动的高效可靠性并发拓扑优化策略。考虑到载荷位置、载荷方向、载荷振幅和材料特性的不确定性,基于顺序策略构建了基于可靠性的高效并发拓扑优化模型。在有效量化多源不确定性带来的非线性特性的基础上,提出了一种基于比例-积分-派生控制器的约束细化运动策略,在一定程度上克服了不确定性量化计算的繁琐。本文提供了位移约束下宏观和微观水平集函数的灵敏度信息。四个数值实例证明了所提方法的有效性、高效性和通用性。


Experimental nonlinear response of a new tensairity structure under cyclic loading

Stefano Catarci, Sawan Kumar Guruva, Biagio Carboni, Giuseppe Quaranta, Walter Lacarbonara

doi:10.1016/j.tws.2024.112163

新型张力结构在循环加载下的实验非线性响应

Pneumatic structures are recognized as promising thin-walled structures for their advantageous features such as lightness, portability, versatile design, and ease of installation. Although their bearing capacity under monotonic static loads can be formidable, their inherent dissipation capacity is low and thus entails significant limitations when counteracting dynamic loads. A novel tensairity structure is here proposed to overcome this drawback. The innovative design features a cylindrical inflatable element integrated with NiTiNOL cables wrapped around and affixed to a slender beam positioned along its generatrix. A laboratory-scale prototype is employed to assess how the structure behaves under cyclic loading in comparison to a standalone inflated beam and a conventional tensairity structure outfitted with steel cables. This experimental study delves into the influence of internal pressure and pretension levels of the metallic cables. Experimental results unfold a smooth softening-type hysteretic behavior under cyclic loading, which is accompanied by a slight stiffness degradation and a moderate pinching. The comparative analysis of the experimental results also demonstrates the substantially improved and consistent dissipation capacity of the presented novel concept of tensairity structure, which thus offers superior stability under cyclic loads. A parametric identification based on a modified Bouc-Wen model is finally performed to simulate the hysteretic response of the structure. A correlation is also established between the identified parameters of the phenomenological model and the internal pressure, type and cables pretension levels. The excellent agreement between numerical predictions and experimental force–displacement cycles other than those used for the parametric identification demonstrates the suitability of the adopted phenomenological modeling.

气动结构因其轻巧、便携、设计多样和易于安装等优点,被认为是一种很有前途的薄壁结构。虽然气动结构在单调静态载荷下的承载能力很强,但其固有的耗散能力较低,因此在抵消动态载荷时受到很大限制。为克服这一缺点,本文提出了一种新型张力结构。这种创新设计的特点是在一个圆柱形充气元件上集成了镍钛硼酸(NiTiNOL)缆线,缆线缠绕并固定在沿其生成轴设置的细长横梁上。采用实验室规模的原型来评估该结构在循环载荷下的表现,并与独立的充气梁和配备钢缆的传统张力结构进行比较。本实验研究深入探讨了金属缆索内部压力和预拉力水平的影响。实验结果表明,在循环荷载作用下,结构会出现平滑的软化型滞后行为,并伴有轻微的刚度下降和适度的挤压。对实验结果的比较分析还表明,所提出的新概念张力结构的耗散能力得到了大幅提高,并保持一致,因此在循环载荷下具有卓越的稳定性。最后,基于改进的 Bouc-Wen 模型进行了参数识别,以模拟结构的滞后响应。此外,还确定了现象模型的确定参数与内部压力、类型和钢索预拉力水平之间的相关性。除用于参数识别的参数外,数值预测与实验力-位移循环之间的极佳一致性证明了所采用的现象模型的适用性。


Bistability-latching criteria in pre-pressurised and electrostatically actuated curved microplates

Lior Medina

doi:10.1016/j.tws.2024.112169

预压和静电驱动曲面微板的双稳态锁定标准

The study of electrostatically actuated microplates in the presence of a mechanical pressure can further their usage as static pressure/mass sensors. The study was carried out using the Föppl-von-Kármán plate model, from which a reduced order (RO) model was derived that includes both loadings. Bistability criteria were extracted semi-analytically using Berger’s plate model, from which a single degree-of-freedom was taken from its RO counterpart. It was found that the bistability interacts with latching in a new manner, requiring two conditions to ascertain if a microplate becomes bistable.

对存在机械压力的静电驱动微板进行研究,可进一步将其用作静压/质量传感器。研究采用了 Föppl-von-Kármán 平板模型,并从中推导出一个包含两种负载的减阶 (RO) 模型。双稳态标准是使用伯杰板模型以半分析方式提取的,该模型的单自由度取自其 RO 对应模型。研究发现,双稳态以一种新的方式与闩锁相互作用,需要两个条件才能确定微孔板是否变成双稳态。


Damage critical transformation mechanisms in milling nickel-based superalloy honeycomb composites using different tool structures

Haihang Wang, Chenguang Wang, Xunxun Zhang, Jiaqiang Dang, Guoqiang Guo, Qinglong An, Weiwei Ming, Ming Chen

doi:10.1016/j.tws.2024.112177

使用不同刀具结构铣削镍基超合金蜂窝复合材料时的损伤临界转化机制

Nickel-based superalloy honeycomb composite (NBSHC) has been developed into an indispensable material for aerospace and defense industries due to light weight, high temperature resistance and extremely high specific strength. Nevertheless, NBSHC is particularly difficult to machine, combing superalloy with thin-walled structure properties, and is prone to damage such as burr, tearing and core deformation. To realize the efficient and low-damage processing of NBSHC, the different tool structures were used during the milling NBSHC experiments under ice-freeing conditions. The material removal mechanisms of different cutters were revealed based on the micro and macro view, and verified by the experiment results. Then, the cutting force and damage behavior of different tools under different parameters during milling NBSHC process were analyzed. For the first time, the damages critical transformation mechanisms during milling NBSHC process were summarized based on above investigations. Results showed that: Since the contact area between saw blade or disc cutters and NBSHC workpiece was a surface, and the in-plane force was small. The qualities of NBSHC machined by saw blade and disc cutters were excellent. Due to the large in-plane force, discontinuity cutting and tearing from removed material, the quality of NBSHC machined by end-milling cutter was extremely terrible. Large cutting force, large contact volume, frequent impacts induced by discontinuity cutting and tearing from the removed material sharply increased the plastic deformation, thus deteriorating the quality of NBSHC and contributing to the transformation of slight damages into severe damages. This work provided significant theories and guidelines for efficient and low-damage machining of NBSHC in aerospace and defense fields.

镍基超合金蜂窝复合材料(NBSHC)具有重量轻、耐高温、比强度高等特点,已发展成为航空航天和国防工业不可或缺的材料。然而,NBSHC 结合了超耐热合金和薄壁结构的特性,加工起来特别困难,而且容易出现毛刺、撕裂和芯材变形等损坏。为了实现对 NBSHC 的高效、低损伤加工,在无冰条件下对 NBSHC 进行铣削实验时使用了不同的刀具结构。从微观和宏观角度揭示了不同刀具的材料去除机理,并通过实验结果进行了验证。然后,分析了铣削 NBSHC 过程中不同刀具在不同参数下的切削力和损伤行为。在此基础上,首次总结了铣削 NBSHC 过程中的损伤临界转化机制。结果表明由于锯片或圆盘铣刀与 NBSHC 工件的接触区域是一个平面,且平面内力较小,因此在 NBSHC 加工过程中,锯片或圆盘铣刀与 NBSHC 工件的接触区域是一个平面,且平面内力较小。用锯片和圆盘铣刀加工出的 NBSHC 质量非常好。而用立铣刀加工的 NBSHC,由于平面力大、切削不连续、材料撕裂等原因,质量极差。切削力大、接触体积大、不连续切削引起的频繁冲击以及被切削材料的撕裂使塑性变形急剧增加,从而使 NBSHC 的质量下降,并导致轻微损伤转变为严重损伤。这项工作为航空航天和国防领域 NBSHC 的高效、低损伤加工提供了重要的理论和指导。


A novel method to determine the critical buckling load for plates from load versus in-plane displacement diagram

Javad Orooji, Mehdi Saeed Kiasat

doi:10.1016/j.tws.2024.112173

从载荷与平面内位移图确定板材临界屈曲载荷的新方法

Based on the literature, the load vs. in-plane displacement diagram (P-u curve) is not sufficiently indicative to provide a reliable determination of the critical buckling load, Pcr. This attitude is rooted in three issues. First, the P-u curve often exhibits very gradual slope changes, second, it concerns unavoidable graph fluctuations caused by imperfections in specimens or boundary conditions, and third, the P-u curve behavior during the buckling phenomenon is not fully understood. In the present work, a narrative review is conducted to gain a better understanding of the location of Pcr on the P-u curve. Accordingly, a novel method is introduced to correctly extract Pcr from the load vs. in-plane displacement diagram as the most accessible buckling test output, compared to out-of-plane displacement and strain monitoring data, which require additional equipment. The proposed method is highly sensitive to changes in the slope of the graph while significantly reducing the adverse effects of undesired fluctuations. This method is applied to several experimental buckling data for composite laminates as well as sandwich panels, and its reliability and accuracy are confirmed by comparison with other well-known methods.

根据文献资料,载荷与平面内位移图(P-u 曲线)的指示作用不足以可靠地确定临界屈曲载荷 Pcr。这种态度源于三个问题。首先,P-u 曲线通常表现出非常渐进的斜率变化;其次,它涉及试样或边界条件不完善所导致的不可避免的图形波动;第三,对屈曲现象中的 P-u 曲线行为还不完全了解。在本研究中,为了更好地理解 Pcr 在 P-u 曲线上的位置,进行了叙述性回顾。因此,与需要额外设备的平面外位移和应变监测数据相比,本研究引入了一种新方法,可从载荷与平面内位移关系图中正确提取 Pcr,而平面外位移和应变监测数据是最容易获得的屈曲试验输出结果。所提出的方法对图形斜率的变化高度敏感,同时显著减少了不希望出现的波动所带来的不利影响。该方法适用于复合材料层压板和夹芯板的多个屈曲试验数据,通过与其他著名方法的比较,证实了其可靠性和准确性。



来源:复合材料力学仿真Composites FEM
ACTMechanicalSystemDeform疲劳断裂复合材料非线性拓扑优化通用航空航天ADS裂纹理论化机材料太阳能控制试验
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首次发布时间:2024-11-21
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【新文速递】2024年6月14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 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 4 篇International Journal of Solids and StructuresThermomechanical-induced cracking model for ceramic matrix composite laminates subjected to thermal gradients and transientsZhengmao Yang, Jiangtao Wang, Rui Yang, Jian Jiaodoi:10.1016/j.ijsolstr.2024.112927受热梯度和瞬态影响的陶瓷基复合材料层压板的热机械诱导开裂模型Regarding the potential damage and failure issues that may occur in high-temperature transient environments during the service process of ceramic matrix composite laminates, the present work proposes a multi-layer thermomechanical induced crack initiation model for ceramic matrix composite laminates subjected to thermal gradients and transients. This model can determine the history of temperature, deformation, and stress distribution within each layer of the material, as well as the steady-state energy release rate of all possible crack locations. Then the influence of bending constraints on material stress distribution and energy release rate is investigated, finding that maximum stress and energy release rate values are significantly lower without bending constraints compared to those under bending constraints. Furthermore, the study explores the impact of material structural parameters and boundary conditions on the energy release rate of ceramic matrix composite laminates, providing direct insights for designing laboratory tests and evaluating the lifespan of these materials under in-service conditions.针对陶瓷基复合材料层压板在使用过程中可能出现的高温瞬态环境下的潜在损坏和失效问题,本研究提出了一种针对陶瓷基复合材料层压板在热梯度和瞬态环境下的多层热机械诱导裂纹起始模型。该模型可确定材料各层内部的温度、变形和应力分布历史,以及所有可能裂纹位置的稳态能量释放率。然后研究了弯曲约束对材料应力分布和能量释放率的影响,发现无弯曲约束时的最大应力值和能量释放率值明显低于有弯曲约束时的值。此外,研究还探讨了材料结构参数和边界条件对陶瓷基复合材料层压板能量释放率的影响,为设计实验室测试和评估这些材料在使用条件下的寿命提供了直接启示。Journal of the Mechanics and Physics of SolidsModeling stochastic elastic wave diffraction by the tips of randomly rough defectsZhengyu Wei, Fan Shi, Zhengjun Wangdoi:10.1016/j.jmps.2024.105744随机粗糙缺陷尖端的随机弹性波衍射建模Elastic wave scattering from a randomly rough surface of a finite length includes surface reflections and diffractions from the tips. Previous research has focused upon reflection waves with applications in ultrasonic defect detection, seismic wave exploration and phonon boundary transport. However, waves diffracted from the tips/edges have been largely neglected so far for rough defects, despite their importance in engineering applications including ultrasonic defect sizing and imaging for assessment of structural integrity. Currently understanding the statistical nature of elastic wave tip diffraction and the role of roughness is limited due to the lack of theoretical studies. In this article, we develop a statistical geometrical tip diffraction (SGTD) theory to rapidly predict the stochastic properties of tip diffraction amplitude as a function of surface roughness and incident angle. By applying a small slope perturbation to the model, a simplified analytical solution of tip diffraction is obtained. It is found that for defects with small to medium roughness, the diffraction amplitude explicitly follows a Gamma distribution, and its mean and the standard deviation are both proportional to the square of the rms slope. High-fidelity Monte Carlo finite element simulations are then run to evaluate the accuracy of the theoretical model. The range of validity of the analytical solution with respect to the level of roughness and the incident angle is obtained. The SGTD method is accurate when the correlation length is approximately equivalent or larger than one wavelength, for a wide range of angles. It is also applicable for a correlation length as short as half wavelength, but only for small rms values and when the beam angle is larger than 45°. In addition, at large angles, the tip diffraction is almost not affected by roughness, being very similar to that from a smooth crack. This is explained by the significant dependence on the beam angle factor explicitly shown in the theoretical solution.有限长度随机粗糙表面的弹性波散射包括表面反射和尖端衍射。以往的研究主要集中于反射波,应用于超声波缺陷检测、地震波探测和声子边界传输。然而,尽管从尖端/边缘衍射的波在工程应用(包括用于评估结构完整性的超声波缺陷大小和成像)中非常重要,但迄今为止,粗糙缺陷的衍射波在很大程度上被忽视了。由于缺乏理论研究,目前对弹性波尖端衍射的统计性质和粗糙度作用的了解还很有限。在本文中,我们开发了一种统计几何尖端衍射 (SGTD) 理论,用于快速预测尖端衍射振幅作为表面粗糙度和入射角函数的随机特性。通过对模型施加小斜率扰动,我们得到了尖端衍射的简化解析解。结果发现,对于小到中等粗糙度的缺陷,衍射振幅明确服从伽马分布,其平均值和标准偏差都与均方根斜率的平方成正比。然后运行高保真蒙特卡洛有限元模拟来评估理论模型的准确性。得出了解析解在粗糙度和入射角方面的有效范围。当相关长度大致等于或大于一个波长时,SGTD 方法在很大的角度范围内都是准确的。它也适用于相关长度短至半波长的情况,但仅限于均方根值较小且光束角度大于 45°的情况。此外,在大角度下,尖端衍射几乎不受粗糙度的影响,与光滑裂纹的衍射非常相似。理论解中明确显示的对光束角系数的显著依赖性解释了这一点。International Journal of PlasticityUnveiling the orientation sensitivity of creep life in near [001] oriented Ni-based single crystal superalloys at intermediate temperaturesPengfei Qu, Wenchao Yang, Qiang Wang, Chen Liu, Jiarun Qin, Jun Zhang, Lin Liudoi:10.1016/j.ijplas.2024.104035揭示近 [001] 取向镍基单晶超合金在中温条件下蠕变寿命的取向敏感性Although blades with a deviation angle of less than 15° between the blade stacking axis and the [001] orientation are qualified in the industry, the creep life of samples near [001] orientation exhibits significant anisotropy at intermediate temperatures. Those crystals having orientations within 15° from precise [001] exhibited significantly longer lives when their orientations were closer to the [001]-[101] boundary of the stereographic triangle than to the [001]-[111] boundary. Here, we first investigated the orientation rotation path of specimens near [001] orientation during creep at 750 ℃/750 MPa, then revealed the dominant slip systems at different creep stages. Subsequently, we evaluated the effect of orientation deviation from precise [001] on creep properties. Finally, our research revealed the orientation sensitive mechanism of creep life in near [001] oriented Ni-based single crystal superalloys at intermediates.虽然叶片堆叠轴线与[001]取向之间的偏差角度小于 15°的叶片在工业上是合格的,但在中间温度下,[001]取向附近样品的蠕变寿命表现出明显的各向异性。取向与精确[001]方向相差 15°以内的晶体,当其取向更接近立体三角形的[001]-[101]边界而非[001]-[111]边界时,其寿命明显更长。在此,我们首先研究了试样在 750 ℃/750 MPa 蠕变过程中靠近[001]取向的取向旋转路径,然后揭示了不同蠕变阶段的主要滑移系统。随后,我们评估了取向偏离精确[001]对蠕变特性的影响。最后,我们的研究揭示了近 [001] 取向镍基单晶超合金在中间阶段蠕变寿命的取向敏感机制。Thin-Walled StructuresTopological Edge States in Reconfigurable Multi-stable Mechanical MetamaterialsZhen Wang, Feiyang Sun, Xiaodong Xu, Xin Li, Chuanqing Chen, Minghui Ludoi:10.1016/j.tws.2024.112111可重构多稳定机械超材料中的拓扑边缘态Multi-stable mechanical structures find cutting-edge applications across various domains due to their reconfigurability, which offers innovative possibilities for engineering and technology advancements. This study explores the emergence of topological states in a one-dimensional chain-like multi-stable mechanical metamaterial composed of bistable units through a combination of mechanical and optical experiments. Drawing inspiration from the SSH (Su-Schrieffer-Heeger) model in condensed matter physics, we leverage the unique mechanical properties of the reconfigurable ligament-oscillator metamaterial to engineer a system with coexisting topological phases. Based on the one-dimensional periodic bistable chain, there is an exponential decay diffusion of elastic energy from both end boundaries towards the interior of the body. Experimental characterizations demonstrate the existence of stable topological phases within the reconfigurable multi-stable mechanical metamaterial. The findings underscore the potential of reconfigurable mechanical metamaterials as versatile platforms for flexibly exploring and manipulating topological phenomena, with applications ranging from impact resistance to energy harvesting and information processing.多稳机械结构因其可重构性而在各个领域都有前沿应用,这为工程和技术进步提供了创新的可能性。本研究通过结合机械和光学实验,探索了由双稳态单元组成的一维链状多稳态机械超材料中拓扑状态的出现。从凝聚态物理学中的 SSH(Su-Schrieffer-Heeger)模型中汲取灵感,我们利用可重构韧带-振荡器超材料的独特机械特性,设计出一种拓扑相共存的系统。基于一维周期性双稳态链,弹性能量从两端边界向主体内部呈指数衰减扩散。实验表征证明了可重构多稳定机械超材料中存在稳定的拓扑相。这些发现强调了可重构机械超材料作为灵活探索和操纵拓扑现象的多功能平台的潜力,其应用范围包括抗冲击、能量收集和信息处理。Plate-type metastructure with low-frequency sound insulation and high stiffness propertiesHeng Ren, Yong Xiao, Huimin Chen, Shuaixing Wang, Hao Zhang, Jihong Wendoi:10.1016/j.tws.2024.112123具有低频隔音和高刚度特性的板式结构According to the mass law, it is impossible to increase sound transmission loss (STL) of conventional structures at low frequencies without increasing their weight. Metastructures are capable to break the limits of the mass law at low frequencies. However, many existing sound insulation metastructures need to be constructed using a host structure with low-stiffness properties, such as a thin plate and a thin membrane. As a result, the metastructures normally have large exposed areas with low-stiffness characteristics and are unable to bear heavy loads, which limits their practical applications. In this work, we propose a high-stiffness plate-type metastructure (HSPM) with both low-frequency sound insulation performance and high stiffness properties. The STL performance of the HSPM is demonstrated analytically, numerically and experimentally, indicating that the HSPM can deeply break the mass law at low frequencies. Owing to the simple construction, high stiffness properties, and high sound insulation performance at low frequencies, the proposed HSPM has promising applications in practical noise control engineering.根据质量定律,传统结构不可能在不增加重量的情况下提高低频声音传输损耗(STL)。转移结构能够在低频下打破质量定律的限制。然而,现有的许多隔音转移结构都需要使用具有低刚度特性的主结构(如薄板和薄膜)来构建。因此,这些转移结构通常具有较大的外露面积和低刚度特性,无法承受重负荷,从而限制了它们的实际应用。在这项工作中,我们提出了一种兼具低频隔音性能和高刚度特性的高刚度板式元结构(HSPM)。我们通过分析、数值和实验证明了 HSPM 的 STL 性能,表明 HSPM 在低频时能深度打破质量定律。由于结构简单、刚度高、低频隔音性能好,所提出的 HSPM 在实际噪声控制工程中具有广阔的应用前景。Effects of steady-state fluid-structure interactions on air-supported membrane structures subjected to wind actionsKeye Yan, Yue Wu, Qiming Zhu, Zhaoqing Chen, Boo Cheong Khoodoi:10.1016/j.tws.2024.112124稳态流固相互作用对受风力作用的气撑膜结构的影响With the perspective of static aeroelasticity, steady-state influences of fluid-structure interaction (FSI) on wind loads and responses of rectangular-planed air-supported membrane structure (ASMS) are investigated in this study. Steady-state FSI simulations are performed by coupling Reynolds-averaged computational fluid dynamics solving wind loads and static finite element analysis solving structural deformations. The feasibility of these simulations is validated with wind tunnel tests concerning time-averaged results. In contrast to analysis without static aeroelasticity, significant variations in wind pressure distributions and amplifications on structural wind responses due to steady-state FSI effects are observed. Subsequently, influencing factors and mechanisms of steady-state FSI effects are analyzed. These time-averaged effects are more significant with the increasing magnitude of structural wind actions, lower internal pressures and less membrane tensile stiffness. Though unlikely to induce irreversible effects as shell structures, the buckling of ASMS can make steady-state FSI more pronounced because of the coupling between stronger flow separation and larger membrane deformations. Accompanied with steady-state FSI, such buckling effect usually contributes to varying locations of the structural maximum responses and noticeable increases in response amplification factors, which deserves attentions in practice. Practically, it is realizable to evaluate these steady-state FSI effects above with simulations because of the much lower computational cost and reliable accuracy.本研究从静态气弹性的角度出发,探讨了流固耦合(FSI)对矩形平面气撑膜结构(ASMS)风荷载和响应的稳态影响。通过雷诺平均计算流体动力学求解风荷载和静态有限元分析求解结构变形,进行了稳态 FSI 模拟。风洞试验的时间平均结果验证了这些模拟的可行性。与无静态气弹分析相比,观察到风压分布的显著变化以及稳态 FSI 效应对结构风响应的放大作用。随后,分析了稳态 FSI 效应的影响因素和机制。这些时间平均效应随着结构风作用强度的增加、内部压力的降低和膜拉伸刚度的减小而变得更加显著。尽管 ASMS 不可能像壳体结构那样产生不可逆的影响,但由于更强的流体分离和更大的膜变形之间的耦合作用,ASMS 的屈曲会使稳态 FSI 更加明显。伴随着稳态 FSI,这种屈曲效应通常会导致结构最大响应位置的变化和响应放大系数的明显增加,这在实践中值得关注。实际上,通过模拟来评估上述稳态 FSI 效应是可行的,因为其计算成本更低,精度更可靠。Shape sensing of the thin-walled beam members by coupling an inverse finite element method with a refined quasi-3D zigzag beam theoryFeifei Zhao, Yanhao Guo, Hong Baodoi:10.1016/j.tws.2024.112127通过将反向有限元法与精炼的准三维之字形梁理论耦合,实现薄壁梁构件的形状传感In structural safety field, the inverse finite element method (iFEM) is an effective methodology to reconstruct full-field displacement on beam, plate and shell structures, independently of the loading conditions and of the material properties. However, the current iFEM in principle requires uniform shear distribution over the thickness of beam, which is practically hardly possible due to these thin-walled beam with the general cross-section shape, such as I-section beam, hat-section beam and box-section beam, and there is no effective method to realize deformation online monitoring at home and abroad. To relieve this issue, a novel iFEM strategy is proposed to establish the shape sensing model of the thin-walled beam, where the thin-walled beam is replaced with an equivalent layered composite one based on a generalized layered global-local beam (GLGB) theory, and the improved quasi-3D zigzag shear deformation theory is presented to describe deformation field of the equivalent layered composite beam. The proposed iFEM method accounts for not only thickness stretching but also interlaminar continuity of shear stresses and displacements. Besides, the proposed iFEM formulation does not need any shear correction factors. Accuracy and effectiveness of the established shape sensing model are demonstrated through several case studies. The numerical results show that the proposed iFEM can accurately reconstruct the deformation of the thin-walled structure and the reconstruction accuracy can be improved by 5%.在结构安全领域,反有限元法(iFEM)是重建梁、板和壳结构全场位移的有效方法,不受加载条件和材料特性的影响。然而,目前的 iFEM 原则上要求在梁的厚度上均匀分布剪力,而由于这些薄壁梁具有一般的截面形状,如工字形截面梁、帽形截面梁和箱形截面梁,这在实际中很难实现,国内外也没有有效的方法来实现变形在线监测。为解决这一问题,本文提出了一种新颖的 iFEM 策略来建立薄壁梁的形状传感模型,即基于广义分层全局梁(GLGB)理论,将薄壁梁替换为等效分层复合梁,并提出改进的准三维之字形剪切变形理论来描述等效分层复合梁的变形场。所提出的 iFEM 方法不仅考虑了厚度拉伸,还考虑了层间剪应力和位移的连续性。此外,拟议的 iFEM 公式不需要任何剪切修正系数。通过几个案例研究,证明了所建立的形状传感模型的准确性和有效性。数值结果表明,所提出的 iFEM 可以准确地重建薄壁结构的变形,而且重建精度可以提高 5%。来源:复合材料力学仿真Composites FEM

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