今日更新：International Journal of Solids and Structures 1 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 6 篇International Journal of Solids and StructuresCarbon fiber reinforced composite 3D origami-inspired auxetic honeycomb with omni-directional high stiffnessYing Gao, Zhibin Li, Xingyu Wei, Yuntong Du, Zhengong Zhou, Jian Xiongdoi:10.1016/j.ijsolstr.2024.112860全方位高刚度的碳纤维增强复合材料三维折纸仿生蜂窝Traditional 3D auxetic materials face significant limitations, marked by low stiffness and pronounced anisotropy. To address these challenges, here a new kind of 3D origami-inspired auxetic honeycomb with omni-directional high stiffness is proposed by us. Two simplified theoretical models based on different assumptions are developed to predict structural homogenized elastic properties along the principal axes. Combined theoretical and numerical studies are carried out to reveal the auxetic mechanism and dominated deformation characteristics of the 3D honeycomb. In order to gain a understanding of its elastic anisotropy, directional dependence of structural homogenized Young’s moduli, Poisson’s ratios and shear moduli are also investigated in detail. A detailed examination of the dependence of structural homogenized Young's moduli, Poisson's ratios, and shear moduli on loading direction is conducted to comprehend its elastic anisotropy. This paper introduces a feasible method for the rapid manufacturing of the 3D honeycomb using high-performance continuous carbon fiber reinforced composite (CFRP) based on hot-pressing molding. Subsequently, the compressive elastic behaviors of CFRP 3D honeycombs are characterized and evaluated through experimental tests. A comparison with traditional 3D auxetic materials reveals the 3D honeycomb's superiority in both multi-axial loading and rapid manufacturing. Additionally, the demonstrative example suggests that the 3D honeycomb can offer nearly isotropic Poisson’s ratio of about −0.9. These results not only demonstrate that the 3D honeycomb is an excellent candidate for applications where both good load-bearing capacity and notable auxetic effect are simultaneously desired but also highlight its potential for 3D isotropic auxetic design.传统的三维增材材料面临着显著的局限性，其特点是低刚度和明显的各向异性。为了解决这些挑战，我们提出了一种新型的全向高刚度的三维折纸型辅助蜂窝结构。基于不同的假设，建立了两个简化的理论模型来预测结构沿主轴的均质弹性特性。通过理论与数值相结合的研究，揭示了三维蜂窝的变形机理和主导变形特征。为了了解其弹性各向异性，还详细研究了结构均匀化杨氏模量、泊松比和剪切模量的方向依赖性。详细研究了结构均质杨氏模量、泊松比和剪切模量对加载方向的依赖关系，以理解其弹性各向异性。介绍了一种基于热压成型的高性能连续碳纤维增强复合材料(CFRP)快速制造三维蜂窝的可行方法。随后，通过试验对CFRP三维蜂窝的压缩弹性性能进行了表征和评价。通过与传统三维增材材料的对比，揭示了三维蜂窝材料在多轴加载和快速制造方面的优势。此外，实验结果表明，三维蜂窝的泊松比接近各向同性，约为−0.9。这些结果不仅表明了三维蜂窝材料在同时需要良好的承载能力和显著的消声效果的应用中是一个很好的候选者，而且突出了其在三维各向同性消声设计中的潜力。International Journal of PlasticityAtomistic investigation of deformation behavior of lamellar pearlite with inclined orientationManjiang Yu, Fangli Duandoi:10.1016/j.ijplas.2024.103988 倾斜取向层状珠光体变形行为的原子研究In this work, a novel model of pearlite colony with inclined orientation is proposed for understanding the deformation behavior of heterogeneous lamellar structures. The simulation results reproduce the experimentally observed dislocation motion parallel to the cementite lamellae and the deformation-induced bending of the cementite lamellae (in colony 2). In the ferrite near the interface, colony 2 has a BCC → HCP → FCC phase transformation path so that it can adapt to the interface mismatch caused by misfit strains as well as the slip deformation after yielding. For the plastic deformation of lamellar pearlite, the {110}〈111〉slip system is observed at the cross-slip, while the {112}〈111〉slip system is embodied at a broader scale. In particular, this work is a step forward in the study of atomic-level deformation and damage in lamellar pearlites with inclined orientations.这项研究提出了一种具有倾斜取向的新型珠光体菌落模型，用于理解异质片层结构的变形行为。模拟结果再现了实验观察到的与雪明碳酸盐层平行的位错运动，以及由变形引起的雪明碳酸盐层弯曲（在菌落 2 中）。在界面附近的铁素体中，菌落 2 具有 BCC → HCP → FCC 相变路径，因此可以适应错配应变引起的界面错配以及屈服后的滑移变形。对于片状珠光体的塑性变形，{110}〈111〉滑移体系是在交叉滑移处观察到的，而{112}〈111〉滑移体系则体现在更广泛的尺度上。特别是，这项工作在研究具有倾斜取向的片状珠光体的原子级变形和损伤方面向前迈进了一步。Thin-Walled StructuresCrystal Plasticity Finite Element Method Investigation of normal tensile deformation anisotropy in rolled pure titanium sheetGang Chen, Yuanming Huo, Jianguo Lin, Tao He, Zhiwei Li, Zhenrong Yan, Hongchao Ji, Hamidreza Ezatpour, Donghai Lindoi:10.1016/j.tws.2024.111904结晶塑性有限元法研究轧制纯钛板的法向拉伸变形各向异性Industrial pure titanium with hexagonal close-packed (HCP) crystal structure has a high degree of anisotropy at room temperature. On the mesoscopic scale, this is due to the rolling texture presented by its crystal orientation. Tensile tests were performed on smooth specimens with five angles in the first quadrant at room temperature, and the central deformation region and fracture region were characterized using EBSD and SEM, respectively. The modified Salem anisotropic hardening model is incorporated into the crystal plasticity finite element method (CPFEM) framework in the form of incremental hardening to describe the initial strength and hardening increment evolution of each deformation system of pure titanium. Both slip dislocation and twinning mechanisms are considered in the CPFEM simulation. Three models with different meshing strategies are used to simulate the tensile conditions to capture the evolution of macro and micro variables of pure titanium sheet. The results show that there are anisotropy in stress-strain, system activity, cumulative shear strain, crystal orientation, twin volume fraction, stress triaxiality and Lode parameter. The purpose of this paper is to explore the anisotropy of macro-meso variables in different directions before damage occurs, so as to provide reference for the subsequent construction of related damage models.具有六方密排(HCP)晶体结构的工业纯钛在室温下具有高度的各向异性。在介观尺度上，这是由于其晶体取向所呈现的滚动织构。在室温下对光滑试样进行第一象限5个角的拉伸试验，分别用EBSD和SEM对中心变形区和断裂区进行表征。将改进的Salem各向异性硬化模型以增量硬化的形式引入到晶体塑性有限元法框架中，描述纯钛各变形体系的初始强度和硬化增量演化过程。在CPFEM模拟中同时考虑了滑移位错和孪晶机制。采用三种不同网格划分策略的模型对纯钛板的拉伸条件进行模拟，以捕捉纯钛板的宏观和微观变量的演变。结果表明:应力-应变、体系活度、累积剪切应变、晶体取向、孪晶体积分数、应力三轴性和Lode参数均具有各向异性;本文旨在探讨损伤发生前宏观细观变量在不同方向上的各向异性，为后续相关损伤模型的构建提供参考。A reliable cyclic envelope model for partially-restrained steel beam-column bolted T-stub connections based on experimental dataYanfei Shen, Mao Li, Yong Lidoi:10.1016/j.tws.2024.111951基于试验数据的部分约束钢梁-柱螺栓t型短段连接可靠循环包络模型The utilization of partially-restrained (PR) steel beam-to-column bolted T-stub connections offers a promising avenue for enhancing the efficiency and resilience of steel structural systems by reducing material consumption and facilitating post-hazard rehabilitation of connection components. However, the practical application of PR T-stub connections faces challenges due to the lack of comprehensive design guidelines. Specifically, in the context of performance-based seismic design for structural systems featuring PR T-stub connections, the accurate characterization of the cyclic envelope is pivotal. Presently, the availability of dependable cyclic envelope models tailored to PR T-stub connections is limited, with existing models facing various limitations. In response to these challenges, this study aims to pioneer a more dependable envelope model capable of mitigating the shortcomings of existing models. To achieve this objective, a comprehensive database comprising experimental data from steel beam-to-column assemblages with T-stub connections subjected to cyclic loading is compiled. These assemblages feature T-stubs either cut from hot-rolled sections or fabricated by welding plates, while the connected beams and columns are hot-rolled members. A four-stage multi-linear cyclic envelope is then developed. Particular attention is given to determining the two key characteristics of PR T-stub connections: maximum strength and initial rotational stiffness. The accuracy and robustness of the developed envelope model are rigorously assessed through comparisons with both experimental results and predictions from existing envelope models.利用部分约束(PR)钢梁-柱螺栓t型短段连接，通过减少材料消耗和促进连接部件的灾后修复，为提高钢结构系统的效率和弹性提供了一条有希望的途径。然而，由于缺乏全面的设计指南，PR T-stub连接的实际应用面临挑战。具体来说，在基于性能的结构体系抗震设计中，循环包络线的准确表征至关重要。目前，针对PR t -存根连接的可靠循环包络模型的可用性有限，现有模型面临各种限制。为了应对这些挑战，本研究旨在开拓一种更可靠的包络模型，能够减轻现有模型的缺点。为了实现这一目标，编制了一个综合数据库，其中包括从钢梁到柱组合的t形短连接受到循环加载的实验数据。这些组合的t型桩要么是从热轧部分切割下来的，要么是由焊接板制成的，而连接的梁和柱是热轧构件。然后开发了一个四阶段多线性循环包络。特别注意的是确定PR t型短节连接的两个关键特性:最大强度和初始旋转刚度。通过与实验结果和现有包络模型的预测结果进行比较，严格评估了所开发的包络模型的准确性和稳健性。Buckling Load Optimization of Sandwich Plates with Trapezoidal Corrugated Core and Elliptical Cutout Using Vibration Correlation Techniques and Artificial Neural Network; Experimental and Numerical AnalysisMohammadjavad Zeinali, Gholamhossein Rahimi, Shahram Hosseinidoi:10.1016/j.tws.2024.111957基于振动相关技术和人工神经网络的梯形波纹芯椭圆切口夹层板屈曲载荷优化实验与数值分析The present research was carried out in order to estimate the buckling load of a sandwich plate with a trapezoidal corrugated core with cut-out using three vibration correlation techniques (VCT). The structure investigated in this research is a sandwich plate with a trapezoidal core and an oval cut-out, which is made of thermoplastic polymer using a 3D printer. By using artificial neural network (ANN) and genetic algorithm (GA), the specific critical buckling load (p¯cr) which is defined as the ratio of critical buckling load (Pcr) to plate weight (gr) has been minimized and the optimal dimensions for cut-out parameters including the ratio of the large diameter of the ellipse (z=20mm) to the small diameter of the ellipse (b) and oval angles with the horizontal axis (a°) are obtained. Using the method of equivalent properties, the trapezoidal core is transformed into an equivalent orthotropic core and finally the desired structure is transformed into a three-layer sandwich plate including homogeneous upper and lower layers and an orthotropic middle layer. By using the meshless method based on radial and polynomial functions and with the help of the finite element method, the numerical simulation of buckling and free vibration of the sandwich plate has been done. The results showed that the estimation of the buckling load with the vibration correlation technique (VCT) corresponds to the actual condition of the structure, so that due to the high quality of sandwich plate construction and its integrity, the results obtained from the first, second, and third methods of the VCT show the effectiveness of this method for predicting of the buckling load of the structure.本研究旨在利用三种振动相关技术（VCT）估算带有梯形波纹芯材和切口的夹层板的屈曲载荷。本研究调查的结构是梯形芯材和椭圆形切口的夹层板，由热塑性聚合物通过 3D 打印机制成。通过使用人工神经网络（ANN）和遗传算法（GA），将特定临界屈曲载荷（p¯cr）（定义为临界屈曲载荷（Pcr）与板重（gr）之比）最小化，并获得切口参数的最佳尺寸，包括椭圆大直径（z=20mm）与椭圆小直径（b）之比以及椭圆与水平轴的夹角（a°）。利用等效特性法，将梯形核心转化为等效正交核心，最后将所需结构转化为三层夹层板，包括均质上层和下层以及正交中间层。通过使用基于径向和多项式函数的无网格方法，并借助有限元方法，对夹层板的屈曲和自由振动进行了数值模拟。结果表明，利用振动相关技术（VCT）估算的屈曲载荷与结构的实际情况相符，因此，由于夹芯板结构的高质量及其完整性，VCT 的第一、第二和第三种方法得出的结果显示了该方法在预测结构屈曲载荷方面的有效性。Effect of nano-silica modified resin on the interface strength and toughness of Al/CFRP hybrid laminatesShixiang Yu, Zhiqiang Zhang, Qin Wang, Hongjie Jia, Mingwen Rendoi:10.1016/j.tws.2024.111967纳米二氧化硅改性树脂对Al/CFRP复合材料界面强度和韧性的影响In order to improve the interfacial strength and toughness of aluminum alloys and CFRP (carbon fiber reinforced plastics) hybrid laminates, modified resin with lower porosity was prepared by adding nano silica treated with silane coupling agent into epoxy resin. Al/CFRP hybrid laminates with modified resin were prepared by physical liquid deposition method and hot-press process. The strength and toughness of Al/CFRP hybrid laminates with modified resin were evaluated by tensile shear test and end notch fracture (ENF) test. The experimental results showed that the interfacial shear strength of Al/CFRP hybrid modified resin laminates is 18.8±0.8MPa and the fracture energy is 1546.33±10.26 J /m2, which is 28.76% and 15.38% higher than that of Al/CFRP hybrid laminates with raw resin, respectively. The well-dispersed silicon nanoparticles effectively mitigate internal stress during the cross-linking process of the modified resin, thereby diminishing the dimensions of microcracks within the modified resin. The transition layer of the modified resin interface formed a cooperative and smooth structure. This structure can ensure that the transition of elements in the interface layer is smooth, and it is not easy to cause stress concentration. The formation of new bonds (C-Si bonds) at the interface of the modified resin indicates an enhancement of bonding strength at the interface, superimposing upon van der Waals forces, thereby enhancing the adhesive strength of the modified resin interface.为了提高铝合金与CFRP(碳纤维增强塑料)复合层压板的界面强度和韧性，在环氧树脂中加入经硅烷偶联剂处理的纳米二氧化硅，制备了低孔隙率的改性树脂。采用物理液相沉积法和热压法制备了改性树脂铝/碳纤维复合材料复合层压板。通过拉伸剪切试验和端缺口断裂(ENF)试验，对改性树脂复合材料Al/CFRP复合材料的强度和韧性进行了评价。实验结果表明，Al/CFRP复合改性树脂层合板的界面抗剪强度为18.8±0.8MPa，断裂能为1546.33±10.26 J /m2，分别比原树脂的Al/CFRP复合层合板提高28.76%和15.38%。分散良好的硅纳米颗粒在改性树脂交联过程中有效地减轻了内应力，从而减小了改性树脂内部微裂纹的尺寸。改性树脂界面的过渡层形成了一个协作的光滑结构。这种结构可以保证界面层中元素的过渡平稳，不易引起应力集中。在改性树脂界面处形成新的键(C-Si键)表明界面处的键合强度增强，叠加在范德华力上，从而提高了改性树脂界面的粘接强度。Axial compressive performance of cruciform timber-encased steel composite columns: Experimental investigation and buckling analysis through 3D laser scanningFeiyang Xu, Zian Zhang, Xinmiao Meng, Xu Wu, Ying Gaodoi:10.1016/j.tws.2024.111968十字形木包钢复合柱轴压性能:三维激光扫描试验研究及屈曲分析Timber-encased steel composite (TESC) columns have garnered increasing attention owing to their high mechanical performance. However, limited studies focus on the compressive performance of cruciform TESC columns and the accurate evaluation of the full-field deformation of the embedded steel component. In this paper, a novel short cruciform TESC column embedded with the thin-walled cruciform steel component was proposed. 22 specimens including TESC columns, bare steel columns and bare glulam columns were tested under axial compression. Parameters including the width and the thickness of cruciform steel components were considered. 3D laser scanning technologies were applied to measure the full-field deformation of 20 steel members, thus quantitatively assessing the reduction in the deformation of steel components resulting from the lateral restraint of timber. Finally, a formula based on nonlinear fitting was established to predict the load-carrying capacity. The results showed that TESC columns exhibited significant enhancements in stiffness and load-carrying capacity. The lateral restraint of timber made the buckling modes of steel change from torsional buckling to mainly local buckling. Moreover, the high post-yield stiffness of steel components before reaching maximum load indicated that the timber offered sufficient lateral restraint to make full use of the steel strength. The 3D laser scanning method accurately measured the full-field deformation of the steel at the failure state. Compared to bare steel columns, the torsional rotation of steel components decreased by up to 83.14%, while the maximum absolute lateral deflection was reduced by up to 80.89%. The suggested strength formula offered sufficient accuracy in predicting the load-carrying capacity of short TESC columns, with the ratios between calculated and experimental values ranging from 0.908 to 1.120.木包钢复合材料(TESC)柱由于其优异的力学性能而受到越来越多的关注。然而，对于十字形TESC柱的抗压性能和预埋钢构件的全场变形的准确评估研究较少。本文提出了一种新型的嵌入薄壁十字形钢构件的短十字形TESC柱。对22个试件进行了轴压试验，包括TESC柱、裸钢柱和裸胶合木柱。考虑了十字形钢构件的宽度和厚度等参数。采用三维激光扫描技术测量了20个钢构件的全场变形，定量评估了木材侧向约束对钢构件变形的减少程度。最后，建立了基于非线性拟合的承载力预测公式。结果表明，TESC柱的刚度和承载能力均有显著提高。木材的侧向约束使钢的屈曲方式由扭转屈曲转变为以局部屈曲为主。此外，在达到最大荷载之前，钢构件的高屈服后刚度表明木材提供了足够的侧向约束，以充分利用钢的强度。三维激光扫描方法精确测量了钢在失效状态下的全场变形。与裸钢柱相比，钢构件扭转角减小83.14%，最大绝对侧向挠度减小80.89%。该强度公式对TESC短柱承载力的预测精度较高，计算值与试验值之比在0.908 ~ 1.120之间。Effect of impact spacing on the dynamic response of UHMWPE fiber composites under two-point high velocity impactsYuhang Xiang, Zhongwei Zhang, Yang Jiang, Xiaoning Yang, Yuan Lin, Guokai Zhang, Chunming Song, Ziming Xiongdoi:10.1016/j.tws.2024.111969冲击间距对两点高速冲击下超高分子量聚乙烯纤维复合材料动力响应的影响The impact from multiple bullets leads to more severe damage to fiber composite laminates, and the dynamic response becomes more complex. However, current research has focused on studying the ballistic limit and single impact response of materials. In this study, an experimental method to investigate the dynamic response and damage modes of fiber composite materials under multi-point asynchronous impacts is proposed. The aim is to reveal the mechanisms behind the differences in ballistic limits and energy absorption of UHMWPE (Ultra-High Molecular Weight Polyethylene) fiber composite panels at different impact distances. Through CT scanning and DIC (Digital Image Correlation) techniques, the delamination area and dynamic response of the laminates were quantitatively analyzed. The results show that the ballistic limit of the second impact is increased by 3.05% when the impact distance is 2.5 times the diameter of the bullet. The maximum difference of energy absorption compared to the first impact was only 3.7% at an impact spacing of 5 times the diameter of the bullet, despite the interference in the damage region. From the perspective of energy absorption, the two impacts are independent. Multiple impact tests are critical for protective materials, and the results of this study provide important insights into UHMWPE fiber laminates in terms of multi-point impact.多弹冲击导致复合材料层合板的损伤更加严重，动力响应更加复杂。然而，目前的研究主要集中在材料的弹道极限和单次冲击响应的研究上。本文提出了一种研究纤维复合材料在多点非同步冲击下的动态响应和损伤模式的实验方法。目的是揭示UHMWPE(超高分子量聚乙烯)纤维复合材料板在不同撞击距离下的弹道极限和能量吸收差异背后的机制。通过CT扫描和DIC(数字图像相关)技术，定量分析了层合板的分层面积和动态响应。结果表明，当冲击距离为子弹直径的2.5倍时，第二次冲击的弹道极限提高了3.05%;当冲击间距为5倍子弹直径时，尽管损伤区域存在干扰，但与第一次冲击相比，能量吸收的最大差异仅为3.7%。从能量吸收的角度来看，这两种影响是独立的。多重冲击试验对防护材料至关重要，本研究结果为超高分子量聚乙烯纤维层压板在多点冲击方面提供了重要见解。来源：复合材料力学仿真Composites FEM
