今日更新：Journal of the Mechanics and Physics of Solids 1 篇，Mechanics of Materials 1 篇，Thin-Walled Structures 6 篇Journal of the Mechanics and Physics of SolidsCollaborative multiscale phase-field model for trans-scale fracture propagation of fiber-reinforced compositesLeying Song, Zhiming Xue, Zhenmeng Xia, Kunjie Wang, Chenghai Xu, Hui Qidoi:10.1016/j.jmps.2024.105686纤维增强复合材料跨尺度断裂扩展的协同多尺度相场模型Owing to their inherent multiscale characteristics, cracks in fiber-reinforced composites initiate and propagate normally at the microscale level during loading, spanning spatial scales up to the macroscopic fracture failure of the material. Motivated by this phenomenon, this study proposes a collaborative multiscale phase-field (CMPF) approach to model the trans-scale fracture propagation of fiber-reinforced composites. The CMPF model includes a region-based phase-field model for characterizing matrix cracking, fiber breaking, and interface debonding at the microscale; a two-modes phase-field model for characterizing the axial and transverse fracture modes at the macroscale; and a bridging model for exchanging information (fracture modes, nonlinear stress–strain relationship, and strain levels) between the macro- and micro-models. Specifically, the real-time attenuation mechanical properties of the composite caused by crack propagation are first obtained at the microscopic scale and then transferred to the macroscopic two-modes phase-field model to map the trans-scale fracture propagation. The CMPF model is implemented within a finite-element package for numerical calculations and then applied to analyze the tensile-fracture behavior of needled carbon/carbon composites, which is a typical type of fiber-reinforced composite. The calculated results show that the transverse fracture mode nucleates successively within the needled region and then in a 90° nonwoven cloth layer, whereas the axial fracture mode arises within a 0° nonwoven cloth layer. The source of the transverse fracture is matrix cracking and that of the axial fracture is fiber breaking at the microscopic scale. In addition, the fracture properties and overlap of the needled region significantly affect the propagation paths of cracks, thus changing the strength and toughness of the composite. This CMPF model offers a promising approach for modeling and understanding the trans-scale fracture mechanisms of fiber-reinforced composites.由于其固有的多尺度特性，纤维增强复合材料的裂纹在加载过程中在微观尺度上形成并正常扩展，跨越空间尺度直至材料的宏观断裂破坏。基于这一现象，本研究提出了一种协同多尺度相场(CMPF)方法来模拟纤维增强复合材料的跨尺度断裂扩展。CMPF模型包括一个基于区域的相场模型，用于表征微尺度下的基体开裂、纤维断裂和界面脱粘;在宏观尺度上描述轴向和横向断裂模式的双模相场模型以及一个桥接模型，用于在宏观和微观模型之间交换信息(断裂模式、非线性应力-应变关系和应变水平)。具体而言，首先在微观尺度上获得裂纹扩展引起的复合材料的实时衰减力学特性，然后将其转换为宏观双模相场模型，以映射跨尺度的断裂扩展。将CMPF模型应用于有限元程序包中进行数值计算，并应用于针 刺碳/碳复合材料的拉伸断裂行为分析，这是一种典型的纤维增强复合材料。计算结果表明，横向断裂模式先在针 刺区形成核，然后在90°无纺布层形成核，而轴向断裂模式在0°无纺布层形成核。在微观尺度上，横向断裂的来源是基体断裂，轴向断裂的来源是纤维断裂。此外，断裂特性和针尖区域的重叠显著影响裂纹的扩展路径，从而改变复合材料的强度和韧性。该CMPF模型为模拟和理解纤维增强复合材料的跨尺度断裂机制提供了一种很有前途的方法。Mechanics of MaterialsMolecular dynamic studies of the micromechanical response of titanium–aluminum layered twin structures and grapheneTinghong Gao, Hong Huang, Jin Huang, Qian Chen, Qingquan Xiaodoi:10.1016/j.mechmat.2024.105050钛铝层状孪晶结构与石墨烯微力学响应的分子动力学研究The nanotwin structure and graphene (Gr)-reinforced phase can significantly enhance the mechanical properties of the material. However, there have been relatively few studies on the mechanisms underlying the strengthening resulting from the interaction between these two components in titanium–aluminum (TiAl) alloy materials. Here, molecular dynamics (MD) simulations were employed to investigate the mechanical properties and microstructural evolution of nanotwinned TiAl/Gr (nt-TiAl/Gr) composites under uniaxial loading. The study investigated the influence of Gr layer number and temperature on composite properties. Results demonstrate that the twin boundary structure interacts with graphene, enhancing mechanical properties synergistically. Relative to pure nt-TiAl, the maximum tensile strength increased by 7.42%, 24.66%, and 35.86% for varying Gr layers. Furthermore, the mechanical properties of nt-TiAl/Gr composites exhibit an inverse correlation with temperature, where maximum tensile strength decreases with temperature elevation. The synergy between Gr and the twin structure significantly inhibits dislocation diffusion and diminishes dislocation nucleation, thus improving the properties of the composite.纳米孪晶结构和石墨烯(Gr)增强相可以显著提高材料的力学性能。然而，关于这两种成分在钛铝(TiAl)合金材料中相互作用的强化机制的研究相对较少。本文采用分子动力学(MD)模拟研究了纳米孪晶TiAl/Gr (nt-TiAl/Gr)复合材料在单轴载荷作用下的力学性能和微观组织演变。研究了Gr层数和温度对复合材料性能的影响。结果表明，双晶界结构与石墨烯相互作用，协同提高了材料的力学性能。相对于纯nt-TiAl，不同Gr层的最大抗拉强度分别提高了7.42%、24.66%和35.86%。此外，nt-TiAl/Gr复合材料的力学性能与温度呈反比关系，最大抗拉强度随温度升高而降低。Gr与孪晶组织的协同作用显著抑制位错扩散，减少位错成核，从而改善复合材料的性能。Thin-Walled StructuresCompressive failure analysis of composite honeycomb sandwich panels with impact damage and stepped-scarf repairsWen Xiao, Ganggang Sha, Xiaohua Lu, Hongfu Zuo, Maosen Cao, Wiesław Ostachowiczdoi:10.1016/j.tws.2024.112012复合材料蜂窝夹芯板冲击损伤及分步修复的压缩破坏分析Composite honeycomb sandwich panels (CHSPs) have been widely used in the aerospace industry owing to their lightweight and superior mechanical properties. However, these CHSPs are susceptible to impact damage, leading to a significant reduction in compressive strength and potentially jeopardize aircraft safety. It is crucial to investigate repair methods for CHSPs with impact damage. This paper aims to evaluate the repair performance of CHSPs with impact damage through an analysis of their compressive failure behaviors. To accomplish this, both experimental tests and advanced numerical models are employed. The numerical models for the intact, damaged and stepped-scarf repaired CHSPs are established using the progressive failure analysis model, cohesive zone model and sandwich plate theory. A good agreement is observed between the experimental results and numerical predictions of compressive failure behaviors. Moreover, the validated numerical models are successfully utilized for determining optimum repair parameters by parametric analysis of the repaired CHSPs. The establishment of these numerical models offers an accurate and cost-effective evaluation of repair performance for CHSPs with impact damage, highlighting the novelty and main contribution of this paper.复合材料蜂窝夹芯板(CHSPs)由于其轻量化和优异的力学性能在航空航天工业中得到了广泛的应用。然而，这些chsp容易受到冲击损坏，导致抗压强度显著降低，并可能危及飞机安全。研究具有冲击损伤的热电堆的修复方法至关重要。本文旨在通过分析chsp的压缩破坏行为来评估其修复性能。为了实现这一目标，采用了实验测试和先进的数值模型。采用递进破坏分析模型、内聚区模型和夹层板理论建立了完整、破损和阶梯式修复的热电机组数值模型。实验结果与数值模拟结果吻合较好。此外，通过对修复后的chsp进行参数分析，成功地将验证的数值模型用于确定最佳修复参数。这些数值模型的建立为具有冲击损伤的热电机组的修复性能提供了准确和经济的评估，突出了本文的新颖性和主要贡献。Mechanical and dynamic performance of 3D-printed continuous carbon fibre Onyx compositesVuong Nguyen-Van, Chenxi Peng, Phuong Tran, Sachini Wickramasinghe, Truong Do, Dong Ruandoi:10.1016/j.tws.2024.1119793d打印连续碳纤维玛瑙复合材料的力学和动态性能The increasing attention towards 3D-printed fibre-reinforced thermoplastic composite structures is due to their superior characteristics, ability to produce intricate architectures, repeatability, and short lead times. This experimental study aims to investigate the mechanical and dynamic behaviours of 3D-printed composite structures under tensile and impact tests. Different types of specimens are designed, including Onyx layers, triangular infill patterns (30% and 40% infill density), and continuous carbon fibre layers (two, four, six, and eight layers). Scanning electron microscopy (SEM) and X-ray micro-computed tomography (μCT) analyses are conducted to visualise the morphological characterisation and observe the delamination and damage of the composite structures. The results of the study reveal that the inclusion of carbon fibre reinforcement layers increases the stiffness and tensile strength of the composite structures. Furthermore, the addition of fibre layers in the composite panels provides critical support in damage resistance against impact loading. In contrast, sandwich structures without reinforcement layers are fatally punctured by the impact force, resulting in significant damage on both the impacted and bottom surfaces. The composite sandwich panels with fewer fibre-reinforced layers and lower infill density become softer and absorb impact energy better.人们越来越关注3d打印纤维增强热塑性复合材料结构，因为它们具有优越的特性，能够生产复杂的结构，可重复性和短的交货时间。本实验研究旨在研究3d打印复合材料结构在拉伸和冲击试验下的力学和动态行为。设计了不同类型的试样，包括玛瑙层、三角形填充图案(30%和40%填充密度)和连续碳纤维层(两层、四层、六层和八层)。利用扫描电子显微镜(SEM)和x射线显微计算机断层扫描(μCT)分析了复合材料的形态特征，并观察了复合材料结构的分层和损伤情况。研究结果表明，碳纤维增强层的加入提高了复合材料结构的刚度和抗拉强度。此外，复合材料板中添加的纤维层提供了抗冲击载荷损伤的关键支撑。相比之下，没有加固层的夹层结构则会被冲击力刺穿，造成撞击面和底面的严重损伤。纤维增强层数较少、填充密度较低的复合材料夹层板具有较好的柔软性和抗冲击性能。Experimental investigation into demountable dry connections for fully precast frame structures through shaking table testsRuijun Zhang, Tong Guo, Aiqun Lidoi:10.1016/j.tws.2024.112014全预制框架结构可拆卸干连接振动台试验研究To fulfill the objective of reducing pollution and carbon emission while advancing the development of high-performance structural systems aligned with green building principles, an innovative demountable dry connection fully precast frame structure system was introduced in this paper. The structure is easy to assemble, can significantly enhance construction efficiency, and facilitates the upgrading and earthquake-damaged replacement of components during service. To comprehensively investigate the dynamic characteristics of this novel precast frame structure, a half-scale specimen structure was manufactured and tested on a shaking table. The seismic performance of the structure was evaluated by collecting and analyzing the data on acceleration, displacement, and strain, as well as observing the deformation and cracking of the structure. The results show that the structure performs well as designed with confined damage, and can achieve the performance target of withstanding minor earthquakes without damage and surviving severe earthquakes without collapsing. After experiencing strong earthquakes, the damage was concentrated on the concrete beams, and the damaged components were easy to demount and replace, which could extend the service life of the structure, ensure the sustainability of the structural seismic resistance, and present an effective solution for achieving environmentally conscious, green, and low-carbon construction practices.为了实现减少污染和碳排放的目标，同时推进符合绿色建筑原则的高性能结构体系的发展，本文介绍了一种创新的可拆卸干连接全预制框架结构体系。该结构易于组装，可显著提高施工效率，便于在使用过程中对部件进行升级和地震损坏更换。为了全面研究这种新型预制框架结构的动力特性，制作了半比例尺结构试件并在振动台上进行了试验。通过收集和分析结构的加速度、位移和应变数据，以及观察结构的变形和开裂，对结构的抗震性能进行了评价。结果表明，该结构性能符合设计要求，损伤有限，能达到小震不破坏、大震不倒塌的性能目标。经历强震后，破坏集中在混凝土梁上，损坏构件易于拆卸和更换，可以延长结构的使用寿命，保证结构抗震的可持续性，为实现环保、绿色、低碳的建筑实践提供了有效的解决方案。Elastic Properties Prediction of Two- and Three-Dimensional Multi-Material LatticesParham Mostofizadeh, Robert A. Dorey, Iman Mohagheghiandoi:10.1016/j.tws.2024.112015 二维和三维多材料晶格的弹性特性预测Advances in multi-material additive manufacturing have opened unprecedented new opportunities for the design and manufacture of lightweight multifunctional structures. The ability to create complex topologies, at a relatively fine resolution, in addition to controlling the material composition on a voxel basis have significantly expanded the design space. To explore this large design space efficiently, accurate and cost-effective modeling tools are essential. In this paper, mechanics-based models for predicting the elastic properties of multi-material 2D and 3D lattice structures are developed or extended. The outcomes are compared with the predictions obtained from finite element models and experimental data. The results reveal that the adapted analytical models demonstrate good accuracy in predicting the elastic modulus of multi-material lattices for relative densities up to approximately 25% while have considerably less computational cost compared to finite element using solid elements (providing the most accurate results in comparison with experiment). Careful consideration of the accuracy of the predictions is necessary for the use of these models for lattices with high relative density values. Besides, several homogenization-based models were studied to investigate their applicability to multi-material lattice structures when the assumption of scale-separation is considered valid. The capability of these models in predicting the whole elasticity tensor and the potential of multi-material lattices in manipulating the anisotropy are demonstrated. Finally, the introduced prediction frameworks are compared in order to provide an overview of their respective advantages and disadvantages in the case of multi-material lattice structures.多材料增材制造技术的进步为轻量化多功能结构的设计和制造提供了前所未有的新机遇。除了在体素基础上控制材料组成外，以相对精细的分辨率创建复杂拓扑的能力大大扩展了设计空间。为了有效地探索这个巨大的设计空间，准确和经济有效的建模工具是必不可少的。本文发展或扩展了基于力学的多材料二维和三维晶格结构弹性特性预测模型。结果与有限元模型和实验数据的预测结果进行了比较。结果表明，适应的分析模型在预测相对密度高达约25%的多材料晶格弹性模量方面表现出良好的准确性，而与使用实体单元的有限元相比，计算成本大大降低(与实验相比，提供了最准确的结果)。对具有高相对密度值的晶格使用这些模型时，必须仔细考虑预测的准确性。此外，还研究了几种基于均质化的模型，以考察其在尺度分离假设成立的情况下对多材料晶格结构的适用性。证明了这些模型在预测整个弹性张量方面的能力以及多材料晶格在控制各向异性方面的潜力。最后，对引入的预测框架进行了比较，以概述其在多材料晶格结构情况下的优缺点。Elastic wave demultiplexer with frequency dependent topological valley Hall edge statesZheng Wu, Jiyue Chen, Weihan Wang, Jie Xu, Shixuan Shao, Rongyu Xia, Zheng Lidoi:10.1016/j.tws.2024.111997 具有频率相关拓扑谷霍尔边缘态的弹性波解复用器Valley Hall topological insulators (VHTIs) hold great promise for enhancing the manipulation of elastic wave propagation by their intrinsic topologically protected mechanism. Different from most of VHTIs designed by the deterministic Dirac degeneracy, a more flexible design of VHTIs is proposed by the accidental Dirac degeneracy to steer elastic wave propagation. Based on the accidental Dirac degeneracy, a kind of hexagonal phononic crystal is designed to independently control the topological phase transitions at different frequency ranges. Consequently, a two-channel topological demultiplexer is designed with the function of frequency separation for flexural waves, and its effectivity is verified by numerical simulations and experimental testing. Comparing with traditional designs of demultiplexers, the VHTIs-based demultiplexer possesses a series of advantages in robust performance, easy fabrication and low energy leakage, and sheds light on developing new generation of elastic wave devices.谷霍尔拓扑绝缘子(VHTIs)凭借其固有的拓扑保护机制，在增强弹性波传播的操纵方面具有很大的前景。与大多数采用确定性狄拉克简并设计的vhti不同，本文采用偶发狄拉克简并设计了一种更灵活的vhti，以引导弹性波的传播。基于偶然狄拉克简并，设计了一种能独立控制不同频率范围拓扑相变的六方声子晶体。为此，设计了一种具有弯曲波分频功能的双通道拓扑解复用器，并通过数值模拟和实验测试验证了其有效性。与传统的解复用器设计相比，基于vhtis的解复用器具有性能稳定、制作简单、能量泄漏小等优点，为开发新一代弹性波器件提供了思路。Review on the protective technologies of bridge against vessel collisionWen Zhe Zhang, Jin Pan, Javier Calderon Sanchez, Xiao Bin Li, Ming Cai Xudoi:10.1016/j.tws.2024.112013桥梁船舶碰撞防护技术综述The collisions between bridges and ships might cause severe damage to both of them, which is impossible to avoid completely, although several specifications or requirements need to be followed in the design of bridges and during the navigation of ships passing bridge. Many researches on protective technology had been conducted to reduce the potentially disastrous consequences. These technologies can be broadly categorized into two main types: the technologies of collision avoidance, which try to reduce the collision possibility by warning the passing ship that might impact the bridge; and passive collision protections, which use protective structures to minimize the damage of bridge and ship due to impact. The purpose of the present paper is to systematically summarize both classifications and then provide insights into their characteristics, advantages, disadvantages, and suitable conditions for application. Additionally, the related approaches originally designed for other applications but with potential relevance are also discussed, such as ship-ship collision avoidance. This review can serve as meaningful guidance and reference for future research and realistic engineering applications.桥梁与船舶的碰撞可能会对双方造成严重的损害，这是不可能完全避免的，尽管在桥梁设计和船舶过桥航行中需要遵循一些规范或要求。为了减少潜在的灾难性后果，人们进行了许多保护技术的研究。这些技术大致可分为两大类:避碰技术，即通过警告过往船只可能撞击桥梁来降低碰撞的可能性;被动碰撞防护，利用防护结构将桥梁和船舶因撞击造成的损害降到最低。本文的目的是系统地总结这两种分类，然后对它们的特点、优点、缺点和适用条件提供见解。此外，还讨论了最初为其他应用而设计但具有潜在相关性的相关方法，例如船-船避碰。对今后的研究和实际工程应用具有一定的指导和借鉴意义。来源：复合材料力学仿真Composites FEM
