【新文速递】2024年10月7日固体力学SCI期刊最新文章

 

今日更新：International Journal of Solids and Structures 3 篇，Journal of the Mechanics and Physics of Solids 3 篇，Mechanics of Materials 1 篇，International Journal of Plasticity 2 篇，Thin-Walled Structures 8 篇

International Journal of Solids and Structures

Coupled thermal-electrical–mechanical characteristics of lightning damage in woven composite honeycomb sandwich structures

Bin Yang, Juhyeong Lee, Yuchen Zhou, Xiaoshan Liu, C. Guedes Soares, Kunkun Fu, Dongmin Yang

doi:10.1016/j.ijsolstr.2024.113090

编织复合材料蜂窝夹层结构雷电损伤的热电力学耦合特性

In this study, lightning strike damage of woven carbon fibre-reinforced polymer laminates (W-CFRPs) and woven composite honeycomb sandwich panels (W-CHSPs) are simulated using the proposed sequential thermal-electrical–mechanical finite element (FE) coupling model incorporating dielectric breakdown of materials. Surface current with an amplitude of 200 kA and corresponding lightning shockwave overpressure were applied on each composite. The FE model coupled with LaRC05 criterion was used to study the failure behaviours of intralaminar damage and interlaminar delamination of the W-CFRPs and W-CHSPs. A series of lightning strike tests were performed to validate the FE model. Detailed lightning damage assessments and mechanisms were characterized by a combination of visual inspection, image processing, ultrasonic scanning and micro computed tomography (Micro-CT) and showed good agreements with the FE-predicted results. It can be concluded that shockwave overpressure significantly impacts lightning-induced damages, thereby supporting the effectiveness of the newly proposed sequential thermal-electrical–mechanical coupling model, which demonstrates improved predictive accuracy.

本研究采用考虑材料介电击穿的顺序热-电-机械有限元耦合模型，对编织碳纤维增强聚合物层合板(W-CFRPs)和编织复合材料蜂窝夹层板(W-CHSPs)的雷击损伤进行了模拟。每个复合材料都施加了幅值为200ka的表面电流和相应的雷电冲击波超压。采用结合LaRC05准则的有限元模型研究了W-CFRPs和w - chsp的层间损伤和层间分层破坏行为。进行了一系列雷击试验来验证有限元模型。结合目视检查、图像处理、超声扫描和微计算机断层扫描(micro - ct)对雷电损伤进行了详细的评估和机制分析，结果与fe预测结果吻合较好。由此可见，冲击波超压对雷击损伤有显著影响，从而支持了新提出的顺序热电力耦合模型的有效性，该模型的预测精度有所提高。

Lattice metamaterials with controllable mechanical properties inspired by projection of four-dimensional hypercubes

Fan Yang, Puhao Li, Zhengmiao Guo, Xiaoyan Li, Jinfeng Zhao, Lihua Wang, Zheng Zhong

doi:10.1016/j.ijsolstr.2024.113091

受四维超立方体投影启发的具有可控力学性能的点阵超材料

There has been an increasing interest among the material research community in the pursuit of enhancing the designability of mechanical properties. The existing approaches usually resorted to sophisticated algorithms (such as machine learning) for the reverse design of materials with specific properties. Different from these existing approaches, here we propose a new approach to create lattice metamaterials with continuously controllable mechanical properties by continuously adjusting the geometric parameters of a unique cell topology originated from the projection of four-dimensional hypercubes. The cells contain an inner region and an outer region, each with different deformation characteristics. For example, the inner region is a stretching-dominated simple cubic (SC) unit cell, while the outer region is a bending-dominated body-centered cubic (BCC) unit cell. Specifically, both stiffness and strength isotropy can be simultaneously realized. The proposed lattice metamaterial exhibits intriguing feature of dual stress plateaus. These plateaus can be effectively controlled by adjusting the geometric parameters of inner and outer regions, which enables these lattice metamaterials to hold promising application prospects in the energy absorption scenarios, such as vehicle and pedestrian protection. Such lattice metamaterial design can be used to realize the gradient distribution of mechanical properties through continuous transition of cell topology without introduction of inefficient interfaces, providing a new approach for the design of heterogeneous metamaterials used in the scenarios involving non-uniform stress distribution.

材料研究界对提高机械性能的可设计性越来越感兴趣。现有的方法通常采用复杂的算法(如机器学习)来对具有特定属性的材料进行反向设计。与这些现有方法不同，本文提出了一种新的方法，通过不断调整源自四维超立方体投影的独特单元拓扑的几何参数来创建具有连续可控力学性能的晶格超材料。单元包含一个内部区域和一个外部区域，每个区域具有不同的变形特征。例如，内部区域是拉伸主导的简单立方(SC)单元格，而外部区域是弯曲主导的体心立方(BCC)单元格。具体来说，刚度和强度各向同性可以同时实现。所提出的晶格超材料表现出双应力高原的有趣特征。通过调整内外区域的几何参数，可以有效地控制这些高原现象，使这些晶格超材料在车辆保护、行人保护等吸能场景中具有广阔的应用前景。这种晶格超材料设计可以在不引入低效界面的情况下，通过单元拓扑的连续过渡实现力学性能的梯度分布，为非均匀应力分布场景下非均质超材料的设计提供了一种新的方法。

A micromechanics-based artificial neural networks model for rapid prediction of mechanical response in short fiber reinforced rubber composites

Shenghao Chen, Qun Li, Yingxuan Dong, Junling Hou

doi:10.1016/j.ijsolstr.2024.113093

基于微力学的短纤维增强橡胶复合材料力学响应快速预测人工神经网络模型

The complex microstructural characteristics inherent in short fiber reinforced rubber composites (SFRRCs) impose considerable computational burdens in predicting the mechanical behavior of such composite materials. To address this challenge, this research extends the applicability of the homogeneous model predicated on the orientation averaging method to encompass composite materials featuring hyperelastic matrices. Combined with finite element method, a comprehensive mechanical response database encompassing various volume fractions and fiber orientation distributions is established. Leveraging this database, a micromechanics-based artificial neural network (ANN) model is meticulously designed to rapidly predict the mechanical response of SFRRCs across varying volume fractions and fiber orientation distributions, utilizing a fixed strain step strategy. To ascertain the efficacy and precision of the developed ANN model, representative volume elements portraying both planar and three-dimensional random distributions of composites are constructed and subjected to finite element analysis. Results indicate that the predicted outcomes from the ANN model align closely with finite element calculations within a certain strain range, while significantly reducing computational costs.

短纤维增强橡胶复合材料(sfrrc)固有的复杂微观结构特性给预测这种复合材料的力学行为带来了相当大的计算负担。为了解决这一挑战，本研究扩展了基于取向平均方法的均匀模型的适用性，以涵盖具有超弹性矩阵的复合材料。结合有限元法，建立了包含不同体积分数和纤维取向分布的综合力学响应数据库。利用该数据库，精心设计了基于微力学的人工神经网络(ANN)模型，利用固定应变阶跃策略，快速预测sfrrc在不同体积分数和纤维取向分布下的力学响应。为了确定所建立的人工神经网络模型的有效性和精度，构建了表征复合材料平面和三维随机分布的代表性体积单元，并对其进行了有限元分析。结果表明，在一定应变范围内，人工神经网络模型的预测结果与有限元计算结果接近，同时显著降低了计算成本。

Journal of the Mechanics and Physics of Solids

Least failure energy density: A comprehensive strength index to evaluate and optimize heterogeneous periodic structures

Huawei Feng, Peidong Lei, Huikai Zhang, Bin Liu

doi:10.1016/j.jmps.2024.105892

最小破坏能量密度:一种评价和优化非均质周期性结构的综合强度指标

Assessing the comprehensive strength of structures under multiple loading conditions is crucial for designing microstructures. This paper proposes the use of the least failure energy density (LFED) to measure the comprehensive strength of heterogeneous periodic structures, which corresponds to the minimum energy density required to destroy a structure. To enhance the comprehensive strength of a periodic structure, the LFED can be maximized. We constructed a two-layer optimization algorithm and found that the high time consumption renders topology optimization unfeasible. We subsequently developed an approach for solving inner-layer optimization analytically and quickly so that the problem becomes a single-layer optimization. We compared the LFED of several classical structures, including plate structures, lattice structures, and TPMSs. The calculations reveal that plate structures exhibit the best performance in terms of LFED, followed by TPMSs whereas truss structures have the poorest performance. Among the three types of classical structures, the octet plate, Schwartz-D minimal surface, and octet truss structures are the best-performing types, respectively. Additionally, the LFED is combined with the BESO topology optimization method to obtain the best 2D periodical structure, a 2D curved-edge kagome structure. For optimal 3D periodical structures, rarely discussed space kagome structures (plate or lattice) are obtained with an LFED superior to that of other counterpart classical structures.

多种载荷条件下结构的综合强度评估是微结构设计的关键。本文提出用最小破坏能量密度(LFED)来测量非均质周期性结构的综合强度，它对应于破坏结构所需的最小能量密度。为了提高周期结构的综合强度，可以最大化LFED。我们构建了一个两层优化算法，发现高耗时使得拓扑优化不可行。我们随后开发了一种方法来解析和快速地解决内层优化，使问题成为一个单层优化。我们比较了几种经典结构的LFED，包括板结构、晶格结构和tpms。计算结果表明，板结构的LFED性能最好，tpms结构次之，而桁架结构的LFED性能最差。在三种经典结构类型中，八柱板、schwarz - d最小曲面和八柱桁架结构分别是性能最好的结构类型。此外，将LFED与BESO拓扑优化方法相结合，得到了最佳的二维周期结构，即二维曲线边kagome结构。对于最优的三维周期结构，得到了很少讨论的空间kagome结构(板或晶格)，其LFED优于其他同类经典结构。

Crack Tip Stress Intensification in Strain-Induced Crystallized Elastomer

Thanh-Tam Mai, Katsuhiko Tsunoda, Kenji Urayama

doi:10.1016/j.jmps.2024.105895

应变诱导结晶弹性体裂纹尖端应力强化

Natural rubber (NR) exhibits strain-induced crystallization (SIC), enhancing tearing strength and crack resistance. However, the reinforcement mechanism along with nonuniform strain around a crack tip remains unclear. We reveal the nonuniform stress field around a crack tip using the DIC-based deformation field data and a hyperelasticity approach. A hyperelastic strain energy density function (W) is derived to be able to replicate stress-strain data across various deformations, encompassing equal and unequal biaxial, uniaxial, and pure shear stretching. These data cover the full range and magnitude of deformations around the crack tip. SIC significantly impacts the singular behaviors of strain and stress near the crack tip, causing a pronounced stress increase and strain decrease within the SIC zone that extends up to approximately 100 μm away from the crack tip. This results in a distinct crossover in singularity power-law index between the SIC zone and the fully amorphous zone. With increasing crack opening, the stress upturn intensifies, and the crossover shifts away from the crack tip due to SIC zone enlargement and local crystallinity increase. These findings deepen our understanding of the physics of SIC near crack tips and its reinforcement mechanism in strain-induced crystallizable soft solid materials.

天然橡胶(NR)表现出应变诱导结晶(SIC)，提高了撕裂强度和抗裂性。然而，裂纹尖端周围非均匀应变的强化机制尚不清楚。我们利用基于dic的变形场数据和超弹性方法揭示了裂纹尖端周围的非均匀应力场。导出了一个超弹性应变能密度函数(W)，能够在各种变形中复 制应力-应变数据，包括相等和不相等的双轴、单轴和纯剪切拉伸。这些数据涵盖了裂纹尖端周围变形的全部范围和幅度。SIC对裂纹尖端应变和应力的奇异行为有显著影响，在距离裂纹尖端约100 μm的SIC区域内，应力显著增加，应变显著减少。这导致在SIC区和完全非晶区之间奇异幂律指数有明显的交叉。随着裂纹张开度的增大，应力上升加剧，由于SIC区扩大和局部结晶度的增加，交叉从裂纹尖端移开。这些发现加深了我们对裂纹尖端附近碳化硅的物理性质及其在应变诱导结晶软固体材料中的增强机制的理解。

Analyzing Flexoelectric Polarization of Suspended Membrane by Nonlinear Bending Theory of Plate

Chunlin Song, Mei Zhang, Wenjie Ming, Xuhui Fan, Boyuan Huang, Jiangyu Li

doi:10.1016/j.jmps.2024.105898

用板的非线性弯曲理论分析悬浮膜的挠曲电极化

Strain gradient breaks inversion symmetry and induces flexoelectric polarization as well as electromechanical coupling in all material systems, though the effect is usually only significant at the nanoscale. Two-dimensional (2D) materials and thin membranes thus provide an ideal platform to explore flexoelectricity, which has been widely pursued, yet quantitative theoretical analysis is needed to guide the rapid experimental developments. In this work, we develop 2D flexoelectric model for suspended membrane based on von Kármán plate theory, and implement it into finite element computation using conforming BCIZ element. Numerical results and discussions on flexoelectric polarization in suspended membrane under uniform pressure or concentrated load are presented, which are validated by piezoresponse force microscopy (PFM) experiments under a range of membrane thicknesses and loading forces showing good agreement with computations. Since large strain gradient often exists in samples with small size in one or two dimensions, the method we develop provides a powerful tool to study a wide range of low-dimensional materials and structures with flexoelectric effect.

在所有材料体系中，应变梯度破坏了反演对称性，诱发了挠曲电极化和机电耦合，尽管这种效应通常只在纳米尺度上显著。因此，二维(2D)材料和薄膜为探索柔性电提供了理想的平台，这已经被广泛追求，但需要定量的理论分析来指导快速的实验发展。本文基于von Kármán板理论建立了悬浮膜的二维柔性电模型，并采用一致性BCIZ单元将其实现到有限元计算中。给出了均匀压力和集中载荷作用下悬浮膜挠曲电极化的数值结果和讨论，并通过压响应力显微镜(PFM)实验对其进行了验证，结果与计算结果吻合较好。由于一维或二维小尺寸样品中往往存在较大的应变梯度，因此我们所开发的方法为研究各种具有挠曲电效应的低维材料和结构提供了有力的工具。

Mechanics of Materials

A cooperative relaxation model with two physical parameters for investigating the temperature and cure dependence of relaxation mechanisms in resins

Xiaotian Mao, Fulin Shang

doi:10.1016/j.mechmat.2024.105172

一个具有两个物理参数的合作松弛模型，用于研究树脂弛豫机制对温度和固化的依赖

Modeling the relaxation properties of resin matrix during cure plays an important role in predicting process-induced residual stresses and final distortions of resin-based composites. This paper develops a physical characterization model, which explains the temperature and cure-degree dependence of relaxation behaviors in terms of the size of cooperatively rearranging region, and special emphasis is placed on investigating the general physical mechanism of cure degree affecting the relaxation properties. In this model, the relaxation time is governed by a modified Adam-Gibbs equation, which is extended here to include the cure dependence. In addition, the relaxation modulus is modeled in a chemo-rheologically simple manner (CSM) based on the free volume theory. Material characterization is carried out using experimental data of two typical resins. It is shown that two cure-dependent model parameters, i.e., the smallest size of the cooperatively rearranging region and the glass transition temperature, are sufficient in accounting for the effect of cure on the relaxation modulus, and could provide a physical explanation of the influence of cure on relaxation behaviors. Furthermore, the proposed model is numerically realized by incorporating ABAQUS with UMAT subroutine, and its validity in predicting the residual stresses and final distortion of composites is also numerically verified by comparing with the results available in literature.

树脂基体在固化过程中的松弛特性建模对于预测树脂基复合材料的工艺残余应力和最终变形具有重要作用。本文建立了一个物理表征模型，解释了弛豫行为在温度和固化程度上对协同重排区域大小的依赖关系，并重点研究了固化程度影响弛豫性质的一般物理机制。在这个模型中，松弛时间由一个修正的亚当-吉布斯方程控制，该方程在这里被扩展到包括治愈依赖。此外，基于自由体积理论，用化学流变简单方法(CSM)对弛豫模量进行了建模。利用两种典型树脂的实验数据进行了材料表征。结果表明，两个与固化相关的模型参数，即协同重排区域的最小尺寸和玻璃化转变温度，足以解释固化对弛豫模量的影响，并可以为固化对弛豫行为的影响提供物理解释。结合ABAQUS和UMAT子程序对模型进行了数值实现，并与文献结果进行了对比，验证了该模型预测复合材料残余应力和最终变形的有效性。

International Journal of Plasticity

Crystal plasticity based investigation of the effects of additive manufactured voids on the strain localization behaviour of Ti-6Al-4V

Haocheng Sun, Esteban P. Busso, Chao Ling, Dong-Feng Li

doi:10.1016/j.ijplas.2024.104141

基于晶体塑性的添加剂制造孔洞对Ti-6Al-4V应变局部化行为影响的研究

The presence of defects produced by additive manufactured (AM) processes in structural Ti alloys such as Ti-6Al-4V is known to have serious implications on the deformation and fatigue behaviour of engineering components. However, there is little understanding about the localised plastic deformation patterns that develop around AM defects, and the associated local conditions that could lead to the nucleation of micro-cracks under creep loading conditions. In this work, the effects of the morphology and volume fraction of AM defects and temperature on the strain localization behaviour around such defects in Ti-6Al-4V will be addressed. To that purpose, a novel rate-dependent crystal plasticity formulation is proposed to describe the mechanical behaviour of the alloy’s predominant α′(HCP)-phase. Representative volume elements (RVEs) of the AM produced microstructures are digitally reconstructed from EBSD orientation maps obtained on planes perpendicular and transversal to the microstructure’s AM growth direction. Calibration of the single crystal model for the α′-phase is carried out from macroscopic uniaxial tensile data from polycrystalline AM specimens at different strain rates and temperatures and published creep data.Furthermore, RVEs containing AM defects of different morphologies and volume fractions are relied upon to investigate the strain localization behaviour around the defects under uniaxial loading at ambient and high temperatures. It is found that the extent of the localised accumulated plastic strain around defects depends greatly on whether the voids surface are smooth or have sharp corners, with the latter being associated with more severe localisation patterns. Moreover, a numerical investigation into the crack initiation behaviour of AM Ti-6Al-4V under uniaxial creep loading at 450 ° C revealed that the development of the local conditions suitable for the nucleation of creep damage/micro-cracks is accelerated in the presence of typical AM defects, and the extent of that acceleration depends strongly on their morphology. An AM defect shape parameter is introduced to quantify the way their morphology affect the time for creep crack initiation/damage.

增材制造（AM）工艺在制造结构性钛合金（如Ti-6Al-4V）时产生的缺陷对工程部件的变形和疲劳行为有着严重影响。然而，对于AM缺陷周围局部塑性变形模式的了解有限，尤其是在蠕变载荷条件下，这些局部条件可能导致微裂纹的萌生。本研究探讨了AM缺陷的形貌、体积分数和温度对Ti-6Al-4V合金缺陷周围应变局部化行为的影响。为此，提出了一种新颖的速率相关晶体塑性模型，用于描述合金中主要的α′(HCP)相的力学行为。通过电子背散射衍射（EBSD）获取的微观结构沿AM生长方向的垂直和横截面取向图，数字重建了AM工艺生成的代表性体积单元（RVE）。对α′相的单晶模型进行了标定，使用来自不同应变速率和温度下的多晶AM试样的宏观单轴拉伸数据以及已发表的蠕变数据进行校准。此外，含有不同形貌和体积分数的AM缺陷的RVE被用于研究在常温和高温单轴加载条件下，缺陷周围的应变局部化行为。研究发现，缺陷表面是否光滑或具有尖角对局部塑性应变的积累程度有显著影响，尖角缺陷会导致更严重的局部化现象。此外，数值研究表明，在450°C单轴蠕变载荷条件下，AM Ti-6Al-4V中的典型AM缺陷会加速局部蠕变损伤/微裂纹萌生的条件形成，且这种加速效应与缺陷的形貌密切相关。为量化缺陷形貌对蠕变裂纹萌生/损伤时间的影响，本文引入了一个AM缺陷形状参数。此研究为进一步理解增材制造缺陷对高温蠕变行为的影响提供了重要依据，并有助于优化增材制造工艺下的钛合金部件设计。

Simultaneous improvement of strength and plasticity: nano-twin construction for a novel high-nitrogen TWIP steel

Sihan Lu, Qingchuan Wang, Tingting Yao, Hao Feng, Ming Gao, Tong Xi, Huabing Li, Lili Tan, Ke Yang

doi:10.1016/j.ijplas.2024.104144

同时提高强度和塑性:一种新型高氮TWIP钢的纳米孪晶结构

For metallic materials, an increase in strength generally results in a decrease in plasticity, and the simultaneous improvement of strength and plasticity (SISP) has been a hot but difficult topic. In this study, through high-nitrogen (N) alloying, a novel high-N twinning-induced plasticity (HN-TWIP) steel was designed. It was surprisingly found that, with higher N content, the SISP was achieved successfully. Compared to 0.3N, the ultimate tensile strength and uniform elongation of 0.6N increased by 95 MPa and 5.6%, respectively. Systematic microstructural analyses indicated that more and thinner twins formed at higher N content during the deformation. Especially, different with conventional TWIP (CV-TWIP) steels, numerous ultrafine nano-twins (<15 nm) were detected in HN-TWIP steels. Combined with the flow stress analyses, their strengthening behavior was found to be attributed to both the N solid solution strengthening and nano-twin strengthening. More importantly, by promoting planar slip, the ultrafine nano-twins provided an additional work-hardening and delayed the necking appearance, which resulted in plasticity enhancement. In other words, the origin of the strength-ductility trade-off avoidance was the nano-twins/ultrafine nano-twins microstructure. Further studies revealed that, by breaking the conflict of low stacking fault energy (SFE) and excellent austenite stability, HN-TWIP steels obtained a breakthrough reduction in SFE. HN-TWIP steels with the extremely low SFE could acquire the special nano-twin microstructure and the SISP mechanical behavior. Accordingly, only by continuously reducing the SFE in the alloying design, the difficult SISP could be realized in TWIP steels. This is a novel and simple strategy for the modification of the metal mechanical properties, and it is meaningful for materials in engineering applications.

对于金属材料来说，强度的提高通常会导致塑性的降低，强度塑性同时提高(SISP)一直是一个热门而又困难的课题。本研究通过高氮(N)合金化，设计了一种新型高氮孪晶塑性(HN-TWIP)钢。令人惊讶的是，当N含量较高时，SISP得以成功实现。与0.3N相比，0.6N的极限拉伸强度和均匀伸长率分别提高了95 MPa和5.6%。系统的显微组织分析表明，在高N含量下，变形过程中形成了更多、更薄的孪晶。特别是，与传统的TWIP (CV-TWIP)钢不同，在HN-TWIP钢中检测到许多超细纳米孪晶(<15 nm)。结合流变应力分析，发现其强化行为可归因于N固溶强化和纳米孪晶强化。更重要的是，通过促进平面滑移，超细纳米孪晶提供了额外的加工硬化，延缓了颈缩的出现，从而提高了塑性。换句话说，强度-延性折衷避免的根源是纳米孪晶/超细纳米孪晶微观结构。进一步的研究表明，通过打破低层错能(SFE)和优异的奥氏体稳定性的冲突，HN-TWIP钢获得了SFE的突破性降低。极低SFE的HN-TWIP钢可以获得特殊的纳米孪晶组织和SISP力学行为。因此，只有在合金设计中不断降低SFE，才能在TWIP钢中实现困难的SISP。这是一种新颖、简便的金属力学性能改性方法，对材料的工程应用具有重要意义。

Thin-Walled Structures

Semi-analytical modeling and vibration characteristics analysis of the orthogonally stiffened cylindrical shell with variable cross-sections of stiffeners

Xuedong Sun, Wei Sun, Xiaofeng Liu, Dongxu Du, Kunpeng Xu, Shang Lv

doi:10.1016/j.tws.2024.112527

变截面加筋正交加筋圆柱壳半解析建模及振动特性分析

The stiffened shell with variable cross-sections of stiffeners (SS-VC) has important applications in aerospace and other fields. Its excellent mechanical properties provide new possibilities for the design and performance improvement of stiffened structural parts. However, its dynamic modeling problems have been urgent to be solved. In this study, the dynamic model of the orthogonally stiffened cylindrical shell with variable cross-sections of stiffeners (OSCS-VC) is established by the semi-analytical method (SAM) and it can be described as follows. The displacement allowable functions of the structure are constructed by using the Gram-Schmidt orthogonalization method. Based on Sanders shell theory, the stress-strain relationships of the longitudinal and ring stiffeners with variable cross-sections are derived under the variable limit integration. The boundary spring stiffness is obtained by the inverse identification technique. The dynamic equation of OSCS-VC is established and solved by using the Lagrange equation. Then, a case study is carried out, the rationality of the semi-analytical dynamic model of OSCS-VC is verified by ANSYS engineering software, literature and the experiment system. Finally, based on the semi-analytical model of OSCS-VC, the influence of the characteristic parameters of cross-sectional functions (CSF) for the longitudinal and ring stiffeners on the natural frequencies is analyzed.

变截面加劲壳在航空航天等领域有着重要的应用。其优异的力学性能为加劲结构件的设计和性能改进提供了新的可能性。然而，其动力学建模问题一直是亟待解决的问题。本研究采用半解析法(SAM)建立了变截面加筋正交加筋圆柱壳(OSCS-VC)的动力模型，其描述如下:采用Gram-Schmidt正交法构造了结构的位移允许函数。基于桑德斯壳理论，推导了变截面纵向加筋和环形加筋在变极限积分下的应力应变关系。采用反辨识法求出边界弹簧刚度。建立了OSCS-VC的动力学方程，并用拉格朗日方程求解。然后，进行了实例研究，通过ANSYS工程软件、文献和实验系统验证了OSCS-VC半解析动力学模型的合理性。最后，基于OSCS-VC半解析模型，分析了纵筋和环筋截面函数特征参数对固有频率的影响。

Investigation of the nonlinear dynamics of thin sandwich shells composed of functionally graded materials with double curvature in thermal environments

Yongqiang Li, Nianzu Wang, Wenkai Yao

doi:10.1016/j.tws.2024.112530

热环境下双曲率功能梯度材料夹层薄壳非线性动力学研究

Double curvature structures play a crucial role as load-bearing components across various engineering fields. Functionally graded materials, blending metals and ceramics, boast superior material characteristics, fueling their expanding applications. This study pioneers the non-linear dynamic analysis of sandwich shells that feature functional gradient compositions in thermal settings. We assume that both the upper and lower shells of these double curvature structures are crafted from functionally graded materials, with a ceramic core. This variation in material exhibits a ceramic layer on the inner surface and a metallic layer on the outer surface, showing properties that vary along the shell thickness in a power-law gradient. Non-linear dynamic equations are derived using third-order shear theory, encompassing geometric non-linearity and shear deformation. Employing the Galerkin method, we discretize the equations of motion into a non-linear dynamic system with five degrees of freedom, and subsequently give an analytical expression for the nonlinear naturalfrequency by means of multiscale analysis. Our discussion examines the impacts of structural parameters, porosity volume fraction, volume fraction index, and temperature differences on the non-linear/linear frequency ratio of doubly curved sandwich shells. Calculations reveal a sharp rise followed by a rapid decline in the non-linear/linear frequency ratio with increasing structural aspect ratio b/a. Conversely, it decreases with increasing thickness-to-length and radius-to-length ratios, with temperature differences initially reducing and later increasing it. These findings offer practical insights for designing functional gradient double curvature sandwich shells.

双曲结构作为承载构件在各个工程领域发挥着至关重要的作用。混合金属和陶瓷的功能梯度材料具有优越的材料特性，促进了其不断扩大的应用。这项研究开创了三明治壳的非线性动态分析，在热环境下具有功能梯度成分。我们假设这些双曲率结构的上下外壳都是由功能梯度材料制成的，具有陶瓷核心。这种材料的变化表现出内表面的陶瓷层和外表面的金属层，显示出沿壳厚度以幂律梯度变化的特性。利用三阶剪切理论推导了非线性动力学方程，包括几何非线性和剪切变形。采用伽辽金方法，将运动方程离散为一个五自由度的非线性动力系统，并通过多尺度分析给出了非线性固有频率的解析表达式。我们的讨论考察了结构参数、孔隙率体积分数、体积分数指数和温度差异对双弯曲夹层壳非线性/线性频率比的影响。计算表明，随着结构长径比b/a的增加，非线性/线性频率比急剧上升，随后迅速下降。相反，随着厚度与长度比和半径与长度比的增加，温度差异先减小后增大。这些发现为设计功能梯度双曲率夹层壳提供了实用的见解。

Asymptotic solutions for heat transfer and stresses in functionally graded porous sandwich pipes subjected to nonuniform pressures and thermal loads

Zhong Zhang, Da Wang, Lu Yao, Zhenyuan Gu, Lijun Ke, Jie Xiao

doi:10.1016/j.tws.2024.112531

非均匀压力和热载荷作用下功能梯度多孔夹层管传热和应力的渐近解

In this work, thermomechanical behaviors of temperature-dependent (TD) functionally graded porous (FGP) sandwich pipes subjected to nonuniform pressures and thermal loads are studied. Because the material properties are variable across the wall of the pipe, seeking exact solutions for the pipe is almost impossible. We use a slice model where the pipe is partitioned into plenty of annular slices and each slice is assumed to have uniform material properties. First, the nonlinear heat transfer along the pipe wall thickness is obtained by introducing an iterative procedure. Then, by using the Fourier series, the mechanical problem is decomposed into axisymmetric and nonaxisymmetric parts. Both the parts can be treated by the state space method and transfer matrix method, and then the superposition principle is used to obtain the displacement and stress distributions. The model results are in good consistency with those obtained from the numerical simulation and those reported in the literature. Finally, an FGP sandwich pipe is considered to discuss the effects of the temperature dependence of material properties (TDMP), power-law index, porosity, and pressure distribution on its thermomechanical behaviors.

本文研究了温度相关(TD)功能梯度多孔(FGP)夹层管在非均匀压力和热载荷作用下的热力学行为。由于材料的性质在管道的整个壁面是可变的，因此对管道寻求精确的解几乎是不可能的。我们使用切片模型，其中管道被分割成大量的环形切片，每个切片都假定具有均匀的材料特性。首先，通过引入迭代法得到沿管壁厚度的非线性换热。然后，利用傅里叶级数将力学问题分解为轴对称部分和非轴对称部分。采用状态空间法和传递矩阵法对两部分进行处理，然后利用叠加原理得到位移和应力分布。模型计算结果与数值模拟结果及文献报道结果吻合较好。最后，以FGP夹芯管为研究对象，讨论了材料性能温度依赖性(TDMP)、幂律指数、孔隙率和压力分布对其热力学行为的影响。

An efficient ultrasound vibration strategy for suppressing intra-bundle pores and regulating pore morphology in carbon fiber-reinforced composites

Xinxin Xu, Kai Wei, Qidong Yang, Ming Mei, Yujia He, Qingling Chen, Xujing Yang

doi:10.1016/j.tws.2024.112532

一种抑制碳纤维增强复合材料束内孔隙和调节孔隙形态的有效超声振动策略

The competitive resin flow between intra- and inter-bundles, always causes the generation of intra-bundle pores during resin transfer molding (RTM), thereby weakening composite mechanical performance. Accordingly, an ultrasound vibration strategy is originally developed to efficiently suppress and improve the spatial morphology and distribution of intra-bundle pores in RTM manufacturing. The effects of ultrasound vibration on the spatial evolution of intra-bundle pores are systematically investigated, furthermore, the suppression mechanisms of intra-bundle pores are revealed. Additionally, an empirical model that predicts porosity under ultrasound vibration, is established and well validated for the developed ultrasound vibration strategy, which provides a feasible path for effectively manufacturing composites. X-ray micro-computed tomography experiments verify that applying a short period of ultrasound vibration balances the dual-scale flow by regulating the modified capillary number, thereby significantly reducing porosity by up to 59.4 %. Numerical analyses indicate that the acoustic cavitation and acoustic flow induced by the ultrasound vibration, facilitate the collapse and transverse migration of larger bubbles, thereby remarkably suppressing the connected pores and larger pores. In particular, the ultrasound vibration strategy completely removes the pores larger than 300 μm. Besides, the collective effects of vibration, compression, and shear forces contribute to forming near-circular pores, which are beneficial for ensuring the expected mechanical performance of composites.

在树脂传递成型(RTM)过程中，束内和束间的竞争树脂流动会导致束内孔隙的产生，从而削弱复合材料的力学性能。因此，为了有效抑制和改善RTM制造中束内孔隙的空间形态和分布，最初开发了一种超声振动策略。系统研究了超声振动对束内孔隙空间演化的影响，揭示了束内孔隙的抑制机制。此外，建立了超声振动下孔隙率预测的经验模型，并对所开发的超声振动策略进行了验证，为有效制造复合材料提供了可行的途径。x射线微计算机断层扫描实验证实，应用短时间的超声振动通过调节修正的毛细管数来平衡双尺度流动，从而显着降低孔隙率，最高可达59.4%。数值分析表明，超声振动引起的声空化和声流有利于较大气泡的崩塌和横向迁移，从而显著抑制连通孔和较大孔。特别是超声振动策略可以完全去除大于300 μm的孔隙。此外，振动、压缩和剪切力的共同作用有助于形成近圆形孔隙，这有利于保证复合材料的预期力学性能。

Smeared fixed crack model for quasi-static and dynamic biaxial flexural response analysis of aluminosilicate glass plates

Zhen Wang, Dayou Ma, Fei Qin

doi:10.1016/j.tws.2024.112533

硅酸铝玻璃板准静态和动态双轴弯曲响应分析的涂抹固定裂纹模型

Glass materials are extensively used in load-bearing structures and impact-resistant components because of their distinctive physical and chemical properties. Accurate predictions and assessment of the mechanical responses of glass structures are crucial for structural design and reliability analysis. In this study, quasi-static and dynamic ball-on-ring (BOR) biaxial flexural tests are conducted on aluminosilicate glass. The smeared fixed crack model is calibrated for deformation and failure analyses. First, the model parameters are calibrated carefully, particularly for different failure criteria. Both the deformation field and fracture modes agree well with the experimental observations during the quasi-static tests. For the low-velocity impact biaxial flexural loading condition, three different numerical techniques, namely the initial scaling tensile strength criterion, non-local approach with energy criterion, and rate-dependent failure stress criterion, are implemented in the numerical models for dynamic failure analysis. Finally, the proposed smeared fixed crack model is compared with the widely used Johnson Holmquist Ⅱ (JH-2) model and demonstrates advantages for low-velocity impact response analysis of glass structures.

玻璃材料由于其独特的物理和化学特性，被广泛应用于承重结构和抗冲击部件中。准确预测和评估玻璃结构的力学响应对结构设计和可靠性分析至关重要。在本研究中，对铝硅酸盐玻璃进行了准静态和动态球环双轴弯曲试验。对涂抹固定裂纹模型进行了校正，用于变形和破坏分析。首先，仔细校准模型参数，特别是针对不同的失效准则。在准静态试验中，变形场和断裂模式与实验结果吻合较好。针对低速冲击双轴弯曲加载工况，采用初始尺度抗拉强度准则、非局部能量准则和速率相关破坏应力准则三种不同的数值方法进行动态破坏分析。最后，将所提出的涂抹固定裂纹模型与广泛使用的Johnson HolmquistⅡ(JH-2)模型进行了比较，证明了涂抹固定裂纹模型在玻璃结构低速冲击响应分析中的优势。

Experimental and theoretical study on axial compression behaviour of the modular combined column

Shuangshuang Jin, Zhuojian Long, Zhijie Cao

doi:10.1016/j.tws.2024.112534

组合式组合柱轴压特性的试验与理论研究

Between the modular units of the modular steel building, there exists a combination of the adjacent modular columns. Due to the gaps between the modular columns and the lack of horizontal connections, the integrity of the modular steel structure is weak, which limits the use of modular steel structures in high-rise buildings. This paper proposes a kind of modular combined column realized the connection of modular single columns through the connectors and concrete, which can improve the integrity of the modular steel building. The assembly process of this new modular combination column is described. For axial compressive performance tests, four modular combined column specimens were designed, each with different height or different number of connecting plates. The axial compressive bearing capacity, ductility, stiffness, and other mechanical parameters of the specimens were analyzed according to the phenomena and load displacement curves of the test. Then, the axial compression failure mode of the modular combined column specimens was compared and analyzed in conjunction with the finite element model. The results indicate that the axial compressive performance and ductility of the combined column suggested in this research are exceptional. The connector can enhance the overall mechanical qualities of the combined column by augmenting the restraining impact of concrete. Finally, the theoretical equation of the axial compression bearing capacity of the modular combined column is obtained by employing the superposition principle, and the equation's reliability is confirmed, along with the test results and the results of the numerical analysis.

在模块化钢结构建筑的模块单元之间，存在相邻模块柱的组合。由于模块化柱之间存在空隙，缺乏水平连接，使得模块化钢结构的整体性较弱，限制了模块化钢结构在高层建筑中的应用。本文提出了一种模块化组合柱，通过连接件与混凝土实现模块化单柱的连接，提高了模块化钢结构建筑的整体性。介绍了这种新型模块化组合柱的装配过程。在轴压性能试验中，设计了4个模块组合柱试件，每个试件具有不同高度或不同连接板数量。根据试验现象和荷载位移曲线，对试件的轴压承载力、延性、刚度等力学参数进行分析。然后，结合有限元模型对组合式柱试件的轴压破坏模式进行了对比分析。结果表明，该组合柱的轴压性能和延性都是优异的。接头可以通过增强混凝土的抑制作用来提高组合柱的整体力学质量。最后，利用叠加原理得到组合式组合柱轴压承载力的理论方程，并结合试验结果和数值分析结果对方程的可靠性进行了验证。

Manipulating localized geometric characteristics in multistable energy-absorbing architected materials

Xianhua Yao, Haiyang Zhao, Ruiqi Ma, Nan Hu

doi:10.1016/j.tws.2024.112535

控制多稳态吸能结构材料的局部几何特性

Optimizing global geometric features of unit cells and their spatial arrangements have been well studied in multistable energy-absorbing architected materials (MEAMs), yet their optimized geometries could lead to highly complex features that require expensive additive manufacturing techniques. In this study, we introduce a generalized design strategy to adjust localized thickness variation of thin curved beams in MEAMs. We numerically identify the optimal non-uniform modulation parameter for maximizing energy trapping capacity across MEAM cells, arrays, and cylinders. Then, quasi-static compression and drop impact tests on MEAM cylinders with non-uniform designs are conducted to prove the proposed method's effectiveness in achieving equivalent energy-absorbing abilities with the same material consumption. Overall, we believe that our easy-to-implement strategy can be applied to any type of MEAM with slender beam elements and embedded into energy-absorbing devices and structures.

在多稳定吸能建筑材料(meam)中，优化单元格的整体几何特征及其空间排列已经得到了很好的研究，但它们的优化几何可能导致高度复杂的特征，需要昂贵的增材制造技术。在本研究中，我们引入了一种广义的设计策略来调整meam中薄弯曲梁的局部厚度变化。我们在数值上确定了最佳的非均匀调制参数，以最大化跨MEAM单元，阵列和圆柱体的能量捕获能力。然后，对非均匀设计的MEAM圆柱进行了准静态压缩和跌落冲击试验，验证了该方法在相同材料消耗下获得等效吸能能力的有效性。总的来说，我们相信我们易于实施的策略可以应用于任何类型的具有细长梁元件的MEAM，并嵌入到吸能装置和结构中。

Impact-resistant performance of DVST sandwich panel under low-velocity impact and numerical cases study of protective effect on RC column

Pengcheng Yuan, Shenchun Xu, Ting Yang, Yun Zhou, Cholap Chong, Chengqing Wu

doi:10.1016/j.tws.2024.112536

低速冲击下DVST夹芯板抗冲击性能及对RC柱保护作用的数值实例研究

A double vertical steel tube (DVST) sandwich panel, with a core layer composed of inner and outer vertical circular hollow steel tubes, was proposed as a sacrificial cladding to mitigate the damage induced by impact loading to reinforced concrete (RC) column. Through experimental tests and numerical simulations, dynamic behaviors of the DVST sandwich panel under low-velocity impact was evaluated. The impacts of varying inner tube diameters and single-layer versus double-layer configurations on the failure mode and the time-history of impact forces of the DVST sandwich panels were examined. The results indicated that the steel tube of the upper layer in double-layer DVST sandwich panels played a crucial role in absorbing impact energy. Additionally, the effectiveness of the DVST sandwich panel as a sacrificial cladding for RC columns under low-velocity impact was investigated. The findings revealed that the presence of the DVST sandwich panel reduced the energy absorbed by the RC column by approximately 60.1%, effectively preserving the integrity of the column while minimizing deformation and damage.

为了减轻冲击荷载对钢筋混凝土柱的损伤，提出了一种双垂直钢管(DVST)夹层板作为牺牲包层，其核心层由内外垂直空心钢管组成。通过试验试验和数值模拟，对DVST夹层板在低速冲击下的动力性能进行了评价。研究了不同内径、单层与双层结构对DVST夹层板破坏模式和冲击力时程的影响。结果表明，双层DVST夹层板的上层钢管对吸收冲击能起着至关重要的作用。此外，还研究了DVST夹层板作为低速冲击下RC柱牺牲包层的有效性。研究结果表明，DVST夹层板的存在使RC柱吸收的能量减少了约60.1%，有效地保持了柱的完整性，同时最大限度地减少了变形和损伤。