今日更新：International Journal of Solids and Structures 2 篇，Journal of the Mechanics and Physics of Solids 1 篇，Mechanics of Materials 1 篇，Thin-Walled Structures 7 篇International Journal of Solids and StructuresFrictional Contact Multi-Point Constraint in Two DimensionsS. Hamed Ebrahimi, Timon Rabczuk, P. Areiasdoi:10.1016/j.ijsolstr.2024.112689二维摩擦接触多点约束Node-to-Segment slideline frictional contact formulation as one of the simplest penalty-based contact algorithms could be further simplified to a general Multi-Point Constraint formulation. This effective MPC formulation is proposed in this paper. Two case specific and a general MPC formulations are proposed which uses the distance vector of the master boundaries with respect to a unique point for the calculation of the contact interaction. Accordingly, the general master surface is reduced to a control node and its MPC distance vector and MPC normal matrix. As a result, the numerous expressions for the contact stiffness matrix will be reduced to its first simple expression, exclusively. Static and dynamic examples are solved to illustrate that the MPC algorithm proposed maintains the same accuracy of Node-to-Segment algorithms while presents the efficiency and user-friendly properties of the multiple-point constraint algorithms used in advanced finite element programs.节点到分段滑线摩擦接触公式作为最简单的基于惩罚的接触算法之一，可以进一步简化为一般的多点约束公式。本文提出了这种有效的 MPC 公式。本文提出了两种针对具体情况的 MPC 计算公式和一种通用 MPC 计算公式，这两种计算公式都使用了主边界相对于唯一点的距离矢量来计算接触相互作用。因此，一般主表面被简化为一个控制节点及其 MPC 距离向量和 MPC 法线矩阵。因此，接触刚度矩阵的众多表达式将被简化为第一个简单表达式，即唯一表达式。通过解决静态和动态示例，说明所提出的 MPC 算法既保持了节点到段算法的精度，又具有高级有限元程序中使用的多点约束算法的效率和用户友好特性。In-plane compression of bi-laterally confined layered structure: Plastic model and parametric studyPengfei Ying, Wenxuan Shen, Zhice Niu, Yong Xiadoi:10.1016/j.ijsolstr.2024.112693双侧约束层状结构的平面内压缩：塑性模型和参数研究Discrete layered structures are commonly used in various functional configurations, such as power batteries. However, the mechanical behavior of the discrete layered structure in the in-plane direction is not well understood due to the complexity of inter-layer interactions. In this study, we investigated the behavior of layered structure under in-plane compression with fixed boundary conditions using theoretical analysis, FE simulations and material tests. In FE simulations, a layered structure could exhibit a specific stable compression deformation pattern until local collapse occurs. To understand the underlying mechanisms, we identified two secondary behaviors, referred to as squeeze elements, during the in-plane compression process. By properly recognizing crucial parameters, we modeled and analyzed the mechanical behaviors of the squeeze elements using plastic theory. The primary behaviors of the layered structure are then explained by examining the mechanical relationship between the squeeze elements and the entirety of the structure. Additionally, the impact of the lateral constraints and the layer numbers on the layered structure is analyzed and verified. Significantly, we discovered a non-monotonic influence of lateral constraints on the maximum energy absorption of the layered structure before local collapse. This finding is further supported by in-plane compression tests conducted on pouch cell batteries. From a structural integrity standpoint, we emphasize the importance of integrated design in the lateral direction to enhance the safety tolerance of functional layered structures subjected to in-plane compression.离散层状结构通常用于各种功能配置，如动力电池。然而，由于层间相互作用的复杂性，人们对离散层状结构在面内方向上的力学行为还不甚了解。在本研究中，我们通过理论分析、有限元模拟和材料测试，研究了层状结构在固定边界条件下的面内压缩行为。在有限元模拟中，层状结构会表现出特定的稳定压缩变形模式，直至发生局部塌陷。为了解其基本机制，我们确定了平面压缩过程中的两种次要行为，即挤压元素。通过正确识别关键参数，我们利用塑性理论对挤压元素的机械行为进行了建模和分析。然后，通过研究挤压元件与整个结构之间的力学关系，解释了分层结构的主要行为。此外，我们还分析并验证了横向约束和层数对分层结构的影响。值得注意的是，我们发现横向约束对局部坍塌前分层结构最大能量吸收的影响是非单调的。对袋装电池进行的平面压缩测试进一步证实了这一发现。从结构完整性的角度来看，我们强调横向综合设计的重要性，以提高功能性分层结构在平面内压缩时的安全承受能力。Journal of the Mechanics and Physics of SolidsA constitutive model for hydrogels with tunable mechanical properties by salting-outJunwei Xu, Jian Li, Xiaocheng Hu, Danming Zhong, Weiqiu Chen, Shaoxing Qudoi:10.1016/j.jmps.2024.105571通过盐析实现机械性能可调的水凝胶构成模型Hydrogels with tunable mechanical properties hold significant potential for applications in various fields. Salting-out has proven to be an effective way for substantially and reversibly regulating the mechanical properties of hydrogels. In this study, we explored the evolution of the mechanical behaviors of Polyacrylamide/Chitosan (PAAm/CS) composite hydrogels with salting-out experimentally, and the results indicate that salting-out treatment can increase the tangent modulus by two orders of magnitude and effectively suppress the strain-softening behavior. However, to date, no constitutive model has been developed that can quantitatively describe the variation of hydrogel mechanical properties with salting-out. To quantify the experimental observations, we developed a micromechanism-based constitutive model. In this model, the stress of hydrogel is contributed by the matrix network and the tunable network, with the latter consisting of cluster domains and connecting domains. Based on the microscopic picture, with further salting-out, the modulus of the cluster domain increases and the volume fraction of the cluster domain decreases synergistically, resulting in the evolution of macroscopic properties. The present model captures the mechanical properties of various hydrogels well, and the finite element analysis exhibits ability to predict complex loading conditions. By designing a novel adjustable phononic crystal structure with PAAm/CS hydrogel, it is demonstrated that the current model will play an important role in guiding the preparation of tunable hydrogels and the application for functional devices.具有可调机械特性的水凝胶在各领域的应用具有巨大潜力。事实证明，盐析是大幅可逆调节水凝胶机械性能的有效方法。在本研究中，我们通过实验探索了聚丙烯酰胺/壳聚糖（PAAm/CS）复合水凝胶在盐析过程中力学行为的演变，结果表明盐析处理可将切线模量提高两个数量级，并有效抑制应变软化行为。然而，迄今为止，还没有建立能定量描述水凝胶力学性能随盐析的变化的构成模型。为了量化实验观察结果，我们建立了一个基于微观力学的构成模型。在该模型中，水凝胶的应力由基质网络和可调网络共同作用，后者由团簇结构域和连接结构域组成。基于微观图景，随着盐析的进一步进行，簇域的模量会增加，而簇域的体积分数会协同减少，从而导致宏观特性的演变。本模型很好地捕捉了各种水凝胶的机械特性，有限元分析显示了预测复杂加载条件的能力。通过设计具有 PAAm/CS 水凝胶的新型可调声波晶体结构，证明当前模型将在指导制备可调水凝胶和应用于功能器件方面发挥重要作用。Mechanics of MaterialsAdapting U-Net for linear elastic stress estimation in polycrystal Zr microstructuresJ.D. Langcaster, D.S. Balint, M.R. Wenmandoi:10.1016/j.mechmat.2024.104948利用 U-Net 估算多晶锆微结构中的线性弹性应力A variant of the U-Net convolutional neural network architecture is proposed to estimate linear elastic compatibility stresses in α-Zr (hcp) polycrystalline grain structures. Training data was generated using VGrain software with a regularity α of 0.73 and uniform random orientation for the grain structures and ABAQUS to evaluate the stress fields using the finite element method. The initial dataset contains 200 samples with 20 held from training for validation. The network gives speedups of around 200x to 6000x using a CPU or GPU, with significant memory savings, compared to finite element analysis with a modest reduction in accuracy of up to 10%. Network performance is not correlated with grain structure regularity or texture, showing generalisation of the network beyond the training set to arbitrary Zr crystal structures. Performance when trained with 200 and 400 samples was measured, finding an improvement in accuracy of approximately 10% when the size of the dataset was doubled.本文提出了一种 U-Net 卷积神经网络架构的变体，用于估算 α-Zr (hcp) 多晶晶粒结构中的线性弹性相容应力。训练数据使用 VGrain 软件生成，晶粒结构的正则度 α 为 0.73，取向为均匀随机取向，并使用 ABAQUS 以有限元方法评估应力场。初始数据集包含 200 个样本，其中 20 个样本来自验证训练。与有限元分析相比，该网络使用 CPU 或 GPU 的速度提高了约 200 倍至 6000 倍，并显著节省了内存，但精度略有降低，最多降低 10%。网络性能与晶粒结构的规则性或质地无关，这表明网络的通用性超出了训练集，可用于任意 Zr 晶体结构。在使用 200 个和 400 个样本进行训练时，对网络性能进行了测量，发现当数据集的大小增加一倍时，准确率提高了约 10%。Thin-Walled StructuresAcoustic emission detection of filament wound CFRP composite structure damage based on Mel spectrogram and deep learningXia-ying Ren, Jie Wang, Yu-jiao Liang, Lian-hua Ma, Wei Zhoudoi:10.1016/j.tws.2024.111683基于梅尔频谱图和深度学习的纤维缠绕 CFRP 复合材料结构损伤声发射检测This paper investigates the hoop tensile mechanical properties, damage mode classification, and damage evolution process of the filament wound CFRP composite structure with different winding angles by acoustic emission and deep learning. Firstly, a clear correspondence between damage modes and peak frequency ranges is established by using k-means clustering results and eight frequency band ranges obtained by wavelet packet transform. On this basis, three damage modes are characterized according to the energy content of different frequency bands. Subsequently, the trained Mel spectrum-CNN classification model is used to identify damage modes and analyze the damage evolution process. The results show that the hoop tensile strength of the filament wound CFRP composite structure with ±55° is higher than that with ±35°. The primary damage modes during the tensile process are matrix cracking and fiber/matrix debonding. The Mel spectrogram-based damage identification method can effectively classify damage modes. In addition, the combination of acoustic emission and deep learning shows significant potential for damage identification and monitoring.本文通过声发射和深度学习研究了不同缠绕角度的长丝缠绕 CFRP 复合材料结构的箍筋拉伸力学性能、损伤模式分类和损伤演化过程。首先，利用 k-means 聚类结果和小波包变换得到的 8 个频带范围，建立了损伤模式与峰值频率范围的明确对应关系。在此基础上，根据不同频段的能量含量确定了三种损伤模式。随后，利用训练好的 Mel spectrum-CNN 分类模型来识别损伤模式并分析损伤演变过程。结果表明，±55°绕丝 CFRP 复合材料结构的环向拉伸强度高于±35°绕丝 CFRP 复合材料结构。拉伸过程中的主要损伤模式为基体开裂和纤维/基体脱粘。基于梅尔频谱图的损伤识别方法可以有效地对损伤模式进行分类。此外，声发射和深度学习的结合在损伤识别和监测方面显示出巨大的潜力。Towards the effect of cracks on the instability of a plate loaded by low-speed axial flowJunzhe Cui, Peng Li, Hong Yin, Dechun Zhang, Yiren Yangdoi:10.1016/j.tws.2024.111685裂缝对低速轴向流加载板失稳的影响This paper presents a model of a cantilevered plate with arbitrary cracks in an axial airflow and the crack’s effect on the plate’s aeroelastic instability. It employs the Dirac function to delineate the effect of cracks on the plate’s bending stiffness and utilizes Fourier series coupled with a mirroring technique to calculate the slope function of the cracked plate. The Theodorsen aerodynamic theory gives the fluid pressure, and the Galerkin method applies to the discretization of the fluid–structure interaction equation. The investigation encompasses three scenarios: single, double, and multiple arbitrary cracks. The flutter boundary of the structure is calculated and analyzed under different parameters. The modal participation factor is used to explore the effect of each structure mode on the plate instability. The results show that cracks significantly affect the plate’s stability. The existence of cracks not only affects the critical flow velocity but also affects the characteristics of the instability mode. When the number of cracks is small, some special positions of the cracks will trigger the structure’s higher-order modes and increase the critical speed. When the number of cracks is large, and the distribution of cracks is uniform, the structural stiffness decreases and critical speed.本文介绍了轴向气流中带有任意裂纹的悬臂板模型，以及裂纹对板的气动弹性不稳定性的影响。它采用狄拉克函数来描述裂纹对板弯曲刚度的影响，并利用傅里叶级数和镜像技术来计算裂纹板的斜率函数。Theodorsen 空气动力学理论给出了流体压力，Galerkin 方法适用于流固耦合方程的离散化。研究包括三种情况：单裂缝、双裂缝和多裂缝。计算并分析了不同参数下的结构扑动边界。利用模态参与因子探讨了每种结构模态对板失稳的影响。结果表明，裂缝会严重影响板的稳定性。裂缝的存在不仅会影响临界流速，还会影响失稳模式的特征。当裂缝数量较少时，裂缝的某些特殊位置会触发结构的高阶模态，并提高临界速度。当裂缝数量较多且分布均匀时，结构刚度会降低，临界速度也会降低。Design of quasi-zero stiffness metamaterials with high reliability via metallic architected materialsWenlong Liu, Quan Zhang, Lingling Wu, Jingbo Sun, Ji Zhoudoi:10.1016/j.tws.2024.111686通过金属结构材料设计具有高可靠性的准零刚度超材料In this paper, a novel design of quasi-zero stiffness (QZS) metamaterials with high-reliability properties is proposed to extend the practical engineering applications as far as possible. The design of the unit cells of the QZS metamaterial is inspired by the natural growth of tree trunks, which have the characteristics of a simple structure and are easy to be processed. The high-reliability properties of QZS metamaterials are realized by introducing metallic-architected materials. Experimental tests are performed to reveal the reliable mechanical response of QZS elements and the ideal low-frequency vibration isolation effect of QZS metamaterials when metallic architected materials are introduced. The proposed QZS metamaterials as well as the high-reliability design paradigm can facilitate the development of QZS metamaterials for low-frequency vibration isolation.本文提出了一种具有高可靠性的准零刚度（QZS）超材料的新型设计，以尽可能扩大实际工程应用。准零刚度超材料单元单元的设计灵感来源于自然生长的树干，树干具有结构简单、易于加工的特点。通过引入金属结构材料，实现了 QZS 超材料的高可靠性。实验测试揭示了 QZS 元件的可靠机械响应，以及引入金属架构材料后 QZS 超材料的理想低频隔振效果。所提出的 QZS 超材料以及高可靠性设计范例有助于开发用于低频振动隔离的 QZS 超材料。Static Analysis on Fatigue Crack Retrofitting Using Steel-Rod Reinforcement MethodCheng Meng, Zhiyuan Yuanzhou, Bohai Ji, Zhuangzhuang Chen, Bang Hedoi:10.1016/j.tws.2024.111687使用钢棒加固法进行疲劳裂缝加固的静态分析Restricted by the closure property of U-rib, the current methods for repairing U-rib fatigue cracks tend to carry the risk of structural damage and new fatigue sources. To mitigate these issues, a new approach, called steel-rod reinforcement (SRR) method, was proposed herein. Theoretical analysis was carried out to investigate the reinforcement mechanism, as well as the numerical simulations. The performance after SRR method was evaluated using static tensile tests, then the parameters were discussed by comparing the effect on reducing stress concentration. The results show that SRR method has good effect on stress concentration reduction at the crack tip. The effective crack length will be reduced, lowering the stress intensity factor, according to the equation presented in this work, after the steel-rods are installed. The maintenance effect improves with an increase in the number of the steel-rods. Reasonable pretightening torque on bolts and recommended distance between steel-rods are suggested as 35 N·m and 40 mm, respectively. The addition of optional round shims with varying thicknesses enhances the applicability of this method.受 U 形肋封闭特性的限制，目前修复 U 形肋疲劳裂纹的方法往往会带来结构损坏和新疲劳源的风险。为缓解这些问题，本文提出了一种新方法，即钢棒加固法（SRR）。我们进行了理论分析以研究加固机制，并进行了数值模拟。通过静态拉伸试验评估了 SRR 方法的性能，然后通过比较参数对减少应力集中的影响进行了讨论。结果表明，SRR 方法对减少裂纹尖端的应力集中有良好效果。安装钢棒后，有效裂纹长度将减少，根据本研究中的方程式，应力强度因子将降低。随着钢棒数量的增加，维护效果也会提高。建议螺栓的合理预紧扭矩和钢棒之间的推荐距离分别为 35 N-m 和 40 mm。增加不同厚度的可选圆形垫片可提高该方法的适用性。On lateral crashworthiness and failure mechanisms of multi-fibers hybrid composite corrugated structures with Carbon, Glass, KevlarYabin Deng, Yuan Yang, Hongyong Jiang, Yiru Rendoi:10.1016/j.tws.2024.111689碳、玻璃和凯夫拉尔多纤维混合波纹复合材料结构的横向耐撞性和破坏机理Fiber hybridization can effectively modulate and control the failure modes of composite structures, thereby altering the mechanical properties. However, the understanding of complex hybrid effects remains insufficient restricting the practical utilization. This study focuses on hybrid composite corrugated structures with carbon, glass, and Kevlar fibers through the lateral crushing experiments on single-fiber corrugated laminates, double-fiber hybridized corrugated laminates, and triple-fiber hybridized corrugated laminates, the crashworthiness, failure mechanism, and hybrid effects are revealed in detail. The experimental results show that (KF3\CF3)S and (CF3\GF3)S exhibit excellent comprehensive performance including SEA and SEA/cost. The high dispersion exhibits negative hybrid effects. Kevlar fiber can effectively inhibit crack propagation and maintain the overall structural integrity. This study has deepened an understanding of the failure mechanisms and hybridization effects of hybrid composite corrugated structures subjected to lateral compressive load, providing guidance for the hybrid design of composite structures.纤维杂化可有效调节和控制复合材料结构的失效模式，从而改变其机械性能。然而，人们对复杂杂化效应的认识仍然不足，限制了其实际应用。本研究通过对单纤维波纹层压板、双纤维杂化波纹层压板和三纤维杂化波纹层压板的横向挤压实验，重点研究了碳纤维、玻璃纤维和凯夫拉纤维的杂化复合波纹结构，详细揭示了其耐撞性、失效机理和杂化效应。实验结果表明(KF3/CF3)S和(CF3/GF3)S具有优异的综合性能，包括SEA和SEA/成本。高分散性表现出负杂化效应。Kevlar 纤维能有效抑制裂纹扩展，保持整体结构的完整性。本研究加深了对承受侧向压缩载荷的混合复合波纹结构的失效机理和混杂效应的理解，为复合材料结构的混杂设计提供了指导。Effect of joint stiffness on the load-carrying capacity of single-layer cylindrical reticulated shell with improved bolt-column (IBC) JointZhicheng Xiao, Ren Li, Huijun Li, Shaozhong Bi, Baohui Lidoi:10.1016/j.tws.2024.111691连接刚度对采用改进型螺栓柱（IBC）连接的单层圆柱网壳承载能力的影响To enlarge the application of single-layer reticulated shells, this study proposes an innovative semi-rigid joint based on the original bolt-column (OBC) joint, referred to as the improved bolt-column (IBC) joint. The mechanical behavior of the IBC joint under the pure load and the coupling effect of bending and axial force is investigated using numerical tests. Then, the practical analytical model of IBC joint is developed based on a three-parameters power model and component method. Subsequently, a mechanical model considering joint stiffness is developed in ANSYS to establish semi-rigidly connected single-layer cylindrical shell. A total of 456 numerical models of shells are conducted to examine the impact of different kinds of joint stiffness on the load-carrying capacity of shells systematically. The results demonstrate that (i) weak axis bending stiffness and axial stiffness significantly affect the load-carrying capacity of shells by approximately 19% and 14% on average respectively; (ii) strong axis bending stiffness and torsional stiffness have relatively minor effects on the critical load of shells, with average decline ratios of only 5% and 6% respectively; (iii) out-of-plane shear stiffness and in-plane shear stiffness exhibit negligible impacts on the load-carrying capacity of shells, with an average effect not exceeding 1%. Finally, the findings of numerical simulation considering all stiffness of IBC joint reveal insights into both varying laws of load-carrying capacity and failure modes for shells. It is observed that the mean critical load can reach up to 59% of the one of rigidly-connected shells, which is significantly higher than those observed in shells with pinned joints.为了扩大单层网壳的应用范围，本研究在原始螺栓-柱（OBC）连接的基础上提出了一种创新的半刚性连接，即改进的螺栓-柱（IBC）连接。通过数值试验研究了 IBC 接头在纯载荷以及弯曲力和轴向力耦合效应下的力学行为。然后，基于三参数动力模型和分量法，建立了 IBC 接头的实用分析模型。随后，在 ANSYS 中建立了考虑连接刚度的力学模型，以建立半刚性连接的单层圆柱壳。共建立了 456 个壳体数值模型，系统地研究了不同连接刚度对壳体承载能力的影响。结果表明：(i) 弱轴弯曲刚度和轴向刚度对壳的承载能力有显著影响，平均影响程度分别约为 19% 和 14%；(ii) 强轴弯曲刚度和扭转刚度对壳的临界载荷影响相对较小，平均下降率分别仅为 5%和 6%；(iii) 面外剪切刚度和面内剪切刚度对壳的承载能力影响微乎其微，平均影响程度不超过 1%。最后，考虑 IBC 接头所有刚度的数值模拟结果揭示了壳体承载能力和破坏模式的变化规律。据观察，平均临界载荷可高达刚性连接壳体的 59%，明显高于带销钉连接的壳体。Experimental tests for the evaluation of the seismic performance of the innovative CFS wallAlessia Campiche, Roberto Tartaglia, Luigi Fiorino, Raffaele Landolfodoi:10.1016/j.tws.2024.111681评估创新 CFS 墙抗震性能的实验测试Lightweight Steel (LWS) systems made of Cold-Formed Steel (CFS) represent a suitable solution for structural systems combining the lightness of the construction with high structural performance under seismic actions. However, till now their structural application in high seismicity areas is still limited. In this framework, the ECCLSA research project was developed to investigate both the structural and thermal performance of an innovative LWS wall lateral force resisting system (LFRS) designed for application in low, moderate and high seismic areas. The introduced system is made by a CFS wall in conjunction with a V-braced system equipped with pre-tensioned Ultra-High-Strength (UHS) steel bars. A design procedure, as well as a large experimental campaign, were conducted to investigate both global and local performance of the introduced wall LFRS. In particular, coupon and relaxation tests were performed to investigate the main material features, while both monotonic and cyclic tests were performed on the whole system. The results show that, if well designed, the introduced LFRS system is able to counter seismic loads concentrating all the plastic deformation within the ultra-high strength bar, leaving in elastic range all the other elements.由冷弯型钢（CFS）制成的轻钢（LWS）系统是结构系统的一种合适解决方案，它将轻质结构与地震作用下的高结构性能相结合。然而，迄今为止，其在地震高发区的结构应用仍然有限。在此框架下，开发了 ECCLSA 研究项目，以研究创新型 LWS 墙体抗侧力系统（LFRS）的结构和热性能，该系统设计用于低、中、高地震区。所引入的系统由 CFS 墙体和装有预张拉超高强度（UHS）钢筋的 V 型支撑系统组成。为研究引入的墙体 LFRS 的整体和局部性能，进行了设计程序和大型实验活动。特别是，为研究主要材料特性，进行了试样和松弛试验，同时对整个系统进行了单调和循环试验。结果表明，如果设计得当，引入的墙体抗震系统能够抵御地震荷载，将所有塑性变形集中在超高强度钢筋内，使所有其他元件处于弹性范围内。来源：复合材料力学仿真Composites FEM
