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
