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【新文速递】2023年11月30日固体力学SCI期刊最新文章

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今日更新:International Journal of Solids and Structures 1 篇,Mechanics of Materials 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 6 篇

International Journal of Solids and Structures

Elliptic crack problem under shear mode in one-dimensional hexagonal quasicrystals with crack surface parallel to the quasiperiodic axis

Ruifeng Zheng, Haining Liu, Peidong Li, Zichen Deng

doi:10.1016/j.ijsolstr.2023.112601

裂纹面平行于准周期轴的一维六方准晶体剪切模式下的椭圆裂纹问题

In this work we are concerned with a special elliptic crack problem in one-dimensional hexagonal quasicrystals. The crack surface is assumed to be parallel to the quasiperiodic axis. A couple of anti-symmetrical uniform shear loadings is applied on the crack surfaces. Taking advantage of the potential theory method, we develop the governing integral equation and obtain the phonon-phason field in terms of simple integrals. The crack slip displacement and the stress intensity factor are derived explicitly. Based on the analytical solution, we investigate the effects of phason filed, crack orientation and the eccentricity of elliptic crack on the important fracture parameters. The solutions obtained in this work are helpful to understand the fracture behavior of one-dimensional hexagonal quasicrystals, especially for the situations in which the cracks are not located on the isotropic planes.

在这项研究中,我们关注的是一维六边形准晶体中的特殊椭圆裂纹问题。假设裂纹表面平行于准周期轴。在裂纹表面施加一对反对称均匀剪切载荷。利用势理论方法,我们建立了控制积分方程,并通过简单积分得到了声子声场。裂纹滑移位移和应力强度因子都是明确推导出来的。在分析解的基础上,我们研究了声子滤波、裂纹取向和椭圆裂纹偏心率对重要断裂参数的影响。本研究获得的解有助于理解一维六方准晶体的断裂行为,尤其是裂纹不位于各向同性平面上的情况。


Mechanics of Materials

Computational homogenization of linear elastic properties in porous non-woven fibrous materials

Mikhail Kuts, James Walker, Pania Newell

doi:10.1016/j.mechmat.2023.104868

多孔无纺纤维材料线性弹性特性的计算同质化

Porous non-woven fibrous media are widely used in various industrial applications such as filtration, insulation, and medical textiles due to their unique structural and functional properties. However, predicting the mechanical behavior of these materials is challenging due to their complex microstructure and anisotropic nature. In this study, a computational model is developed to simulate the mechanical response of porous non-woven fibrous media under external loading. The model is based on the finite element method and takes into account the geometric and material properties of the fibers and the void spaces between them. The effects of various factors such as fiber size, porosity, and fibers’ intersection ratio on the mechanical behavior of the material are investigated. The results reveal that the material’s porosity and fibers’ intersection ratio are the most significant factors influencing its mechanical properties. Additionally, the increase in fiber diameter has a relatively minor effect on the material’s elastic properties. However, such changes in elastic properties are primarily attributed to the increase in randomness within the fibrous network, which is directly related to the fiber diameter for the investigated structure. The proposed computational model predicts the mechanical properties of porous non-woven fibrous media and can provide invaluable insights into the design and optimization of porous non-woven fibrous media for various scientific and engineering applications.

多孔非织造纤维介质因其独特的结构和功能特性,被广泛应用于过滤、绝缘和医用纺织品等各种工业领域。然而,由于其复杂的微观结构和各向异性,预测这些材料的机械行为具有挑战性。本研究开发了一个计算模型,用于模拟多孔无纺纤维介质在外部负载下的机械响应。该模型基于有限元法,考虑了纤维的几何和材料特性以及纤维之间的空隙。研究了纤维尺寸、孔隙率和纤维交叉比等各种因素对材料力学行为的影响。研究结果表明,材料的孔隙率和纤维交叉比是影响其机械性能的最重要因素。此外,纤维直径的增加对材料弹性性能的影响相对较小。不过,弹性性能的这种变化主要归因于纤维网内部随机性的增加,而随机性的增加与所研究结构的纤维直径直接相关。所提出的计算模型可以预测多孔非织造纤维介质的力学性能,并为设计和优化多孔非织造纤维介质的各种科学和工程应用提供宝贵的见解。


International Journal of Plasticity

Heterostructure Manipulation of Ti2AlNb Alloy through Directional Induction Heating: Investigation of Multi-Scale Deformation Mechanisms in the O Phase

Zedong Liu, Jieren Yang, Xiaoliang Zhao, Ruirun Chen

doi:10.1016/j.ijplas.2023.103830

通过定向感应加热操纵 Ti2AlNb 合金的异质结构:研究 O 相的多尺度变形机制

In this study, a heterostructure of Ti2AlNb alloy (Ti-22Al-26Nb) was fabricated using directional heating treatment (DHT) technology. The microstructure of the alloy was examined before and after DHT treatment using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The primary objective of the study is to investigate the deformation mode and strain hardening mechanism in the multi-scale O phase. The results indicate that DHT treatment leads to a significant refinement in the grain size of the alloy, resulting in a 14.2% increase in ultimate tensile strength (UTS) and a 29.2% increase in elongation. However, the treatment also causes a decrease in yield strength. The soft phase region, characterized by the microstructure with micron-sized O phase precipitates, and the hard phase region, characterized by the microstructure with submicron-sized O phase precipitates, exhibit different modes of strain adjustment. To mitigate the internal stress arising from the deformation mismatch between the soft and hard phases, the micron-sized O phase activates slip on the {110} and {010} planes during the tensile process at room temperature. Additionally, twinning behavior was observed on the {110} plane. On the other hand, the submicron O-phase activates slip on the {041} plane and occurs a crystal rotation of approximately 90 degrees along the 〈012〉and 〈100〉orientations. These high-angle grain boundaries (HAGBs), which form continuously during deformation, effectively store dislocations and contribute to a continuous strain hardening effect in the alloy. Additionally, the alloy exhibits a high strain hardening ability due to the accumulation of geometrically necessary dislocations caused by the strain gradient resulting from the uneven plastic deformation of the soft and hard phase components, as well as the potential hetero deformation-induced (HDI) hardening. Ultimately, a Ti2AlNb alloy with a favorable balance of UTS and elongation was achieved.

本研究采用定向加热处理(DHT)技术制造了一种 Ti2AlNb 合金(Ti-22Al-26Nb)异质结构。使用扫描电子显微镜(SEM)和电子反向散射衍射(EBSD)检查了定向加热处理前后合金的微观结构。研究的主要目的是探究多尺度 O 相的变形模式和应变硬化机制。结果表明,DHT 处理可显著细化合金的晶粒尺寸,使极限拉伸强度 (UTS) 提高 14.2%,伸长率提高 29.2%。不过,这种处理也会导致屈服强度下降。以微米级 O 相析出物微观结构为特征的软相区和以亚微米级 O 相析出物微观结构为特征的硬相区呈现出不同的应变调整模式。在室温拉伸过程中,为了缓解软硬相之间的变形不匹配所产生的内应力,微米级的 O 相在{110}和{010}平面上产生滑移。此外,在{110}面上还观察到了孪晶行为。另一方面,亚微米级的 O 相会激活{041}面上的滑移,并沿 〈012〉和 〈100〉方向发生约 90 度的晶体旋转。这些在变形过程中不断形成的高角度晶界(HAGBs)有效地储存了位错,并在合金中产生了持续的应变硬化效应。此外,由于软硬相成分的不均匀塑性变形所产生的应变梯度以及潜在的异质变形诱导硬化(HDI)所导致的几何必要位错的积累,该合金表现出很高的应变硬化能力。最终,Ti2AlNb 合金实现了 UTS 和伸长率的良好平衡。


Thin-Walled Structures

Flexural capacity and local buckling half-wavelength of high strength steel tubular beams under moment gradients: an experimental study

Zichang Yang, Xin Meng, Fiona Walport, Leroy Gardner

doi:10.1016/j.tws.2023.111420

弯矩梯度下高强度钢管梁的抗弯能力和局部屈曲半波长:实验研究

An experimental investigation into the effect of moment gradients on the flexural behaviour of hot-rolled high strength steel square hollow section (SHS) beams is presented in this paper. In total, 20 beam specimens in steel grades S690 and S770, and with cross-sections spanning from Class 2 to Class 4 based on the Eurocode 3 slenderness limits, were tested under three- and four-point bending. In the three-point bending tests, the beam spans were varied to achieve a range of moment gradients; the influence of different stiffening arrangements at the loading point was also considered. Local geometric imperfections were measured by means of 3D laser-scanning prior to testing and digital image correlation (DIC) was adopted to monitor the displacement and strain fields at critical regions and to assess the local buckling half-wavelengths of the test specimens for which a consistent measurement approach was proposed. The measured local buckling half-wavelengths were compared against the elastic local buckling half-wavelengths calculated using the finite strip method. It was observed that while the measured local buckling half-wavelengths remained approximately constant up to first yield, a significant reduction in half-wavelength was observed with increasing moment due to the non-uniform spread of plasticity. The comparisons also revealed that the local buckling half-wavelengths reduced with both the presence of moment gradients and intermediate stiffeners, with a new parameter proposed to quantify the local moment gradient. It was shown from the tests that the specimens subjected to moment gradients, despite the presence of shear, exhibited higher ultimate moment capacities (up to 10.5% for stiffened specimens and 3.4% for unstiffened specimens) than those subjected to uniform moments. This is attributed to the delay in the local buckling of the critical cross-section of beams under moment gradients due to the restraint provided by the less heavily stressed adjacent cross-sections.

本文介绍了力矩梯度对热轧高强度方形空心型钢(SHS)梁弯曲性能影响的实验研究。在三点和四点弯曲试验中,共测试了 20 个钢级为 S690 和 S770 的横截面试样,其横截面跨度从 2 级到 4 级(基于欧洲规范 3 的纤度限值)。在三点弯曲试验中,改变了梁的跨度,以实现一系列力矩梯度;还考虑了加载点处不同加劲安排的影响。测试前通过三维激光扫描测量了局部几何缺陷,并采用数字图像相关技术(DIC)监测了关键区域的位移和应变场,评估了测试样本的局部屈曲半波长,并提出了一致的测量方法。将测得的局部屈曲半长与使用有限条带法计算的弹性局部屈曲半长进行了比较。结果表明,虽然测得的局部屈曲半波长在首次屈曲前大致保持不变,但由于塑性扩散不均匀,随着力矩的增加,半波长显著减少。比较结果还显示,局部屈曲半长随力矩梯度和中间加强筋的存在而减小,并提出了一个新参数来量化局部力矩梯度。试验结果表明,尽管存在剪力,但受力矩梯度作用的试样比受均一力矩作用的试样具有更高的极限力矩承载能力(加劲试样高达 10.5%,非加劲试样为 3.4%)。这是因为在弯矩梯度作用下,由于受力较小的相邻截面提供了约束,梁的临界截面局部屈曲发生了延迟。


Fluid-Solid Coupling for Microscale Transport of Nanoparticles in Ultralong Carbon Nanotubes

Jiantao Leng, Tienchong Chang

doi:10.1016/j.tws.2023.111431

超长碳纳米管中纳米粒子微尺度传输的流固耦合

Achieving microscale motion of nanoparticles is crucial for the development of various nanodevices. Here we propose a novel fluid-solid coupling device that leverages a thermally-induced water flow to enable long-range nanoparticle transport within carbon nanotubes (CNTs). Our device comprises an ultralong CNT filled with water, composed of repeated units. Each unit experiences an asymmetrical thermal gradient induced by intentionally incorporating asymmetrical configurations of atomic vacancies on the CNT surface. Through molecular dynamics (MD) simulations, we demonstrate that these repeated units with periodic thermal fields effectively induce a steady water flow, enabling continuous transportation of a nanoparticle (e.g., a C60 fullerene) within the ultralong CNT over microscale distances. Moreover, we reveal that the device can be also designed with various alternative options (e.g., Stone-Wales defects or carbon/boron-nitride heterojunctions). Our proposed device holds promising potential for microscale nanoparticle transport applications.

实现纳米粒子的微尺度运动对于各种纳米器件的开发至关重要。在此,我们提出了一种新型流固耦合装置,利用热诱导水流实现纳米粒子在碳纳米管(CNT)内的长程传输。我们的装置包括一个充满水的超长 CNT,由重复单元组成。通过有意在 CNT 表面加入非对称配置的原子空位,每个单元都会经历非对称的热梯度。通过分子动力学(MD)模拟,我们证明了这些具有周期性热场的重复单元能有效地诱导稳定的水流,从而使纳米粒子(如 C60 富勒烯)在超长 CNT 内的微观距离上持续传输。此外,我们还发现该装置还可以设计成各种替代方案(如石-威尔士缺陷或碳/氮化硼异质结)。我们提出的装置在微尺度纳米粒子传输应用方面具有广阔的前景。


Mechanical properties prediction and design of curved beams by neural network

Junhua Zhang, Xiao Xue

doi:10.1016/j.tws.2023.111434

利用神经网络预测和设计曲线梁的力学性能

It is known that curved beams are used widely in vibration isolation and noise reduction. The curved beam can show bistable, negative stiffness and other mechanical characteristics in the compression process through design. The preflex beam absorbs energy during the multi-state jump process and can recover its initial configuration after undergoing loading and unloading, so it is an ideal energy absorb component. In this paper, preflex beams are designed and the mechanical properties are studied and predicted by neural network. Firstly, a large number of finite element models for sinusoidal preflex beams are built by using Python randomly selected the parameters of beams. Secondly, the dataset corresponding to the parameters of the beams and mechanical properties is established. The variation trend of mechanical properties such as initial stiffness, force threshold, negative stiffness and total absorbed energy with the change of structural parameters and the sensitivity of structural parameters to the above mechanical indexes are obtained. Thirdly, by substituting the data set into the artificial neural network, the trained neural network can predict the mechanical properties of the beams within the allowable error range. At last, a new type of preflex beam with porous section is proposed in order to optimize the specific absorbed energy of the preflex beam. After data screening and optimization, the specific absorbed energy of the porous preflex beam is increased by 15.56% compared with the beam whose section without porous. The results obtained show that the data-driven method can greatly shorten the structural design time and expand the design space. This study will provide a theoretical basis for the wider application of preflex beams in engineering field.

众所周知,曲线梁在隔振和降噪方面应用广泛。通过设计,曲线梁在压缩过程中可表现出双稳态、负刚度等力学特性。预弯梁在多态跃变过程中吸收能量,并能在加载和卸载后恢复初始构型,是一种理想的吸能部件。本文设计了预弯梁,并利用神经网络对其力学性能进行了研究和预测。首先,通过 Python 随机选择梁的参数,建立了大量正弦波预弯梁的有限元模型。其次,建立与梁参数和力学性能相对应的数据集。得出初始刚度、力阈值、负刚度和总吸收能量等力学性能随结构参数变化的变化趋势,以及结构参数对上述力学指标的敏感性。第三,将数据集代入人工神经网络,经过训练的神经网络可以在允许误差范围内预测梁的力学性能。最后,为了优化预弯梁的比吸收能量,提出了一种新型多孔预弯梁。经过数据筛选和优化,多孔预制梁的比吸收能比无孔预制梁提高了 15.56%。结果表明,数据驱动法可以大大缩短结构设计时间,拓展设计空间。这项研究将为预弯梁在工程领域的广泛应用提供理论依据。


Hysteretic performance of thin-walled Q690 high-strength steel H-section beam-columns bent about the weak-axis

Zhongqi Chen, Mark A. Bradford, Guo-Qiang Li, Yan-Bo Wang, Guotao Yang

doi:10.1016/j.tws.2023.111436

围绕弱轴弯曲的薄壁 Q690 高强度钢 H 型钢梁柱的滞回性能

High-strength steel has broad application prospects in steel structures as its weight to strength ratio is low, but the reduced ductility limits its application in seismic design. In order to evaluate the application potential of high-strength steel in light steel structures, four Q690 high-strength steel beam-columns with large width to thickness ratios were tested under cyclic loading about the weak axis. The failure mode, ultimate strength, hysteretic curve, stiffness degradation, ductility and energy dissipation capacity of the tested specimens are discussed. Subsequently, a finite element analysis model is established, and an extensive parametric study is carried out using the verified finite element model. The test results show that the failure mode is the local buckling of column base. The hysteretic behavior of the specimens is mainly affected by the axial load ratio and the flange width to thickness ratio. The results of the parametric study show that the extent of development of plasticity in the cross-section is related to the axial load ratio. The calculated ultimate strength of the beam-column shows that Eurocode 3 is conservative for the classification of the beam-column as having a Class 4 cross-section, members with Class 4 cross-sections should in fact be classified as having Class 3 cross-sections. Accordingly, a section classification for a high-strength steel beam-column subjected to weak axis bending is discussed.

高强度钢的重量强度比低,在钢结构中具有广阔的应用前景,但其延性较差,限制了其在抗震设计中的应用。为了评估高强度钢在轻钢结构中的应用潜力,我们对四根宽厚比较大的 Q690 高强度钢梁柱进行了绕弱轴循环加载试验。讨论了试验试件的破坏模式、极限强度、滞回曲线、刚度退化、延性和耗能能力。随后,建立了有限元分析模型,并利用验证后的有限元模型进行了广泛的参数研究。试验结果表明,破坏模式是柱基的局部屈曲。试件的滞回行为主要受轴向载荷比和翼板宽厚比的影响。参数研究结果表明,横截面塑性的发展程度与轴向荷载比有关。计算得出的梁柱极限强度表明,《欧洲规范 3》将梁柱划分为 4 级截面是保守的,具有 4 级截面的构件实际上应划分为 3 级截面。因此,本文讨论了承受弱轴弯曲的高强度钢梁柱的截面分类。


Impact dynamic response of large aperture space deployable antenna supporting structures based on a dual-scale model

Lu Jin, Boheng Li, Dake Tian, Qinghe Wang, Yinyin Hou

doi:10.1016/j.tws.2023.111432

基于双尺度模型的大孔径空间可部署天线支撑结构的冲击动态响应

This study investigates the joint damage patterns and changes in shape accuracy of large aperture space deployable antenna supporting structures subject to hypervelocity impacts from micro space debris. Based on the dual-scale method, a joint scale model is constructed for a hexagonal prismatic space deployable truss antenna supporting structure with an aperture of six meters and 37 modules. ANSYS/AUTODYN is used for the impact damage analysis, with an equivalent model of impact force integrating the structure's actual damage characteristics in the structure scale model. The dynamic response and deformation performance of the antenna supporting structure under impact velocities from 2.5 to 15.0 km/s, with spherical space debris of 2.5 mm and 5.0 mm diameters, impacting modular central points in both positive and negative directions, are analyzed. The results show that the primary damage to the joint scale model after impact includes cratering, perforation, punch failure, and joint failure. The debris diameter significantly influences joint damage and deformation of the bolt hole diameter. Additionally, the debris cloud post-impact significantly affects the vertical bar's inner wall, spalling the wall and reducing the rod's strength. As the impact point moves towards the structure's centroid, the antenna's overall response increases. With higher impact velocities, the antenna supporting structure's overall deformation first increases, then decreases. At an impact velocity of 12.5 km/s, the impact area of the structure gradually reduces post-impact. Our proposed joint damage forms and three-case damage classification (no effect, repairable, and joint failure) may serve as a valuable reference for designing structural protection and impact identification for space deployable antennas.

本研究探讨了大孔径空间可部署天线支撑结构在受到微型空间碎片超高速撞击时的联合损伤模式和形状精度变化。基于双尺度法,为一个孔径为 6 米、有 37 个模块的六角棱柱形空间可展开桁架天线支撑结构构建了一个联合尺度模型。ANSYS/AUTODYN 用于冲击损伤分析,冲击力等效模型将结构的实际损伤特征整合到结构比例模型中。分析了天线支撑结构在 2.5 至 15.0 千米/秒的撞击速度下的动态响应和变形性能,直径分别为 2.5 毫米和 5.0 毫米的球形空间碎片从正反两个方向撞击模块中心点。结果表明,撞击后关节比例模型的主要损伤包括缩孔、穿孔、冲孔失效和关节失效。碎片直径对接头损坏和螺栓孔直径变形有很大影响。此外,撞击后的碎片云对垂直杆的内壁有很大影响,使内壁剥落并降低杆的强度。随着撞击点向结构中心移动,天线的整体响应也随之增加。随着撞击速度的增加,天线支撑结构的整体变形先增大后减小。在 12.5 km/s 的撞击速度下,结构的撞击面积在撞击后逐渐减小。我们提出的关节损坏形式和三种损坏情况分类(无影响、可修复和关节损坏)可为空间可部署天线的结构保护设计和撞击识别提供有价值的参考。


Numerical study and design of ultra-high-strength steel plate girders subjected to patch loading after elevated temperature

Zeqiao Luo, Yu Shi, Xuanyi Xue, Yunpeng Xu, Lei Xu

doi:10.1016/j.tws.2023.111433

高温后承受贴片荷载的超高强度钢板梁的数值研究与设计

When a steel structure does not collapse after a fire, it is meaningful to study its residual resistance after exposure to elevated temperatures to evaluate its post-fire service capacity. The elevated temperatures of a fire change the residual mechanical properties of structural steel, which influences the patch-loading resistance performance of steel plate girders. However, the effects of temperature on the residual resistance performance of Q960 ultra-high-strength steel (UHSS) plate girders subjected to patch loading remain unclear. This study aims to determine the variation trends of the post-fire bearing performance of Q960 UHSS plate girders subjected to patch loading based on their mechanical properties after exposure to elevated temperature and natural cooling. The effects of the web width-to-height ratio, web height-to-thickness ratio, load length, and exposure temperature were considered in the parametric study; a total of 400 numerical models were included. Additionally, the influence of the exposure temperature on the serviceability limit state of Q960 UHSS plate girders was considered. The applicability of EN 1993-1-5 was verified based on the finite element analysis results, which showed that the design methods in EN 1993-1-5 significantly underestimated the ultimate resistance of Q960 UHSS plate girders exposed to elevated temperatures. Thus, the strength reduction function in EN 1993-1-5 was revised to improve the accuracy of the statistical analysis.

当钢结构在火灾后没有倒塌时,研究其暴露于高温后的残余阻力以评估其火灾后的使用能力是非常有意义的。火灾中的高温会改变钢结构的残余力学性能,从而影响钢板梁的抗补载性能。然而,温度对 Q960 超高强度钢(UHSS)钢板梁承受贴片加载的残余抗压性能的影响仍不清楚。本研究旨在根据 Q960 超高强度钢板梁在暴露于高温和自然冷却后的力学性能,确定承受补丁加载的 Q960 超高强度钢板梁火灾后承载性能的变化趋势。参数研究考虑了腹板宽高比、腹板高厚比、荷载长度和暴露温度的影响,共包括 400 个数值模型。此外,还考虑了暴露温度对 Q960 超高强度钢板梁适用性极限状态的影响。有限元分析结果表明,EN 1993-1-5 中的设计方法大大低估了暴露在高温下的 Q960 超高强度聚苯乙烯板梁的极限抗力。因此,对 EN 1993-1-5 中的强度降低函数进行了修订,以提高统计分析的准确性。



来源:复合材料力学仿真Composites FEM
ACTMechanicalAutodynDeform断裂电子ADS裂纹理论化机材料分子动力学多尺度控制试验纺织螺栓
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【新文速递】2023年11月21日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 3 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 5 篇International Journal of Solids and StructuresHyperspace bounds on mixed mode elastic constants of n-component transversely-isotropic unidirectional materialsPham Duc-Chinhdoi:10.1016/j.ijsolstr.2023.112584n 分量横向各向同性单向材料混合模式弹性常数的超空间界限We consider the general elastic unidirectional composites composed of n transversely-isotropic components (with unidirectional cylindrical boundaries between the phases), which are just macroscopically isotropic in the transverse plane. All 6 mixed-mode elastic constants appear in the complex mixed-mode longitudinal-transverse stress–strain relations (not well-separated into the pure hydrostatic and deviatoric modes as in the usual problems concerning the 3D- or 2D-isotropic bulk and shear moduli). They are subjected to various combination bounds, derived from the minimum energy principles, involving many effective properties simultaneously in the multidimensional-elastic-constant hyperspace. Exploring the possible trial mixed stress–strain modes, we derive from the combination bounds the new sets of bounds, with additional and more refined ones, on all 6 effective mixed-mode longitudinal-transverse constants of the n-component transversely-isotropic unidirectional composites, which improve significantly over the previous results. Refined optimization techniques have been used in conjunction with the iteration procedure. Using Hill relations relating the exact values of some of the effective elastic constants in the two-component case, the bench-mark Paul-Hill-type bounds have also been deduced for all those 6 mixed elastic constants for comparisons with our new bounds (three of them appear to coincide with those of ours, while the others comparatively are near-to-close in numerical examples) in that specific case. Illustrating numerical examples are provided for some two- and multi-component cases. Related to the subject - the matrix approach on bounding elastic anisotropic composites in the literature is critically examined.我们考虑的是由 n 个横向各向同性成分(各相之间的边界为单向圆柱形)组成的一般弹性单向复合材料,它们在横向平面上只是宏观各向同性。所有 6 个混合模式弹性常数都出现在复杂的纵向-横向混合模式应力-应变关系中(并不像通常的三维或二维各向同性体积模量和剪切模量问题那样,被很好地区分为纯静压模式和偏离模式)。它们受制于各种组合约束,这些约束源于最小能量原则,同时涉及多维弹性常数超空间中的许多有效特性。在探索可能的试验混合应力-应变模式的过程中,我们从组合约束中推导出了新的约束集,并对 n 组横向各向同性单向复合材料的全部 6 种有效混合模式纵向-横向常数进行了补充和完善,与之前的结果相比有了显著改善。结合迭代程序使用了改进的优化技术。利用与双组分情况下某些有效弹性常数精确值相关的希尔关系,还推导出了所有这 6 个混合弹性常数的保罗-希尔型基准边界,以便与我们在该特定情况下的新边界进行比较(其中 3 个似乎与我们的边界相吻合,而其他边界在数值示例中相对接近)。我们还提供了一些双组分和多组分情况的数值示例。与本课题相关的是,我们对文献中关于弹性各向异性复合材料边界的矩阵方法进行了批判性研究。New buckling solutions of truncated conical shells incorporating pre-buckling nonlinearityZhou Chao, Gong Guangping, Chen Liang, Wang Bo, Li Ruidoi:10.1016/j.ijsolstr.2023.112587包含预屈曲非线性的截顶锥壳新屈曲解法The pre-buckling nonlinearity is found to have a remarkable effect on both the buckling loads and modes of shells according to the previous studies. In this study, we present a novel accurate buckling analysis of the truncated conical shells under broad boundary constraints incorporating the pre-buckling nonlinearity by a quasilinearization-precise integral method (Q-PIM). Specifically, the nonlinear buckling equations of the shells are transformed into several linear ones by the perturbation and quasilinearization, and they are then solved by the PIM. The produced state transition equations by the PIM are assembled into a global matrix equation, involving the boundary conditions (BCs), to yield the buckling solutions of the shells with or without incorporating the pre-buckling nonlinearity. The convergence study and benchmark buckling solutions verified by the refined finite element method are presented. The quantitative effects of the size parameters and BCs on the nonlinear critical buckling loads as well as the pre-buckling nonlinearity are investigated.以往的研究发现,预屈曲非线性对壳的屈曲载荷和模式都有显著影响。在本研究中,我们采用准线性化-精确积分法(Q-PIM),结合预屈曲非线性,对宽边界约束下的截顶锥形壳体进行了一种新的精确屈曲分析。具体来说,通过扰动和准线性化将壳体的非线性屈曲方程转化为多个线性方程,然后用 PIM 求解。由 PIM 生成的状态转换方程被组合成一个全局矩阵方程,其中涉及边界条件 (BC),从而得到包含或不包含预屈曲非线性的壳体屈曲解。本文介绍了收敛性研究和通过精炼有限元法验证的基准屈曲解。研究了尺寸参数和 BCs 对非线性临界屈曲载荷以及预屈曲非线性的定量影响。Rate-dependent peeling behavior of the viscoelastic film-substrate systemYin Hanbin, Ma Yinji, Feng Xuedoi:10.1016/j.ijsolstr.2023.112588粘弹性薄膜-基底系统随速率变化的剥离行为In contrast to the well-understood peeling behavior of an elastic film-substrate system, the peeling behavior of a viscoelastic film bonded to a rigid substrate remains unclear. This paper established a theoretical peeling model, assuming a uniformly distributed cohesive interfacial interaction, to study the steady-state peeling behavior of a viscoelastic film. The rate-dependent behaviors of the steady-state peeling force and cohesive zone length are mainly analyzed in the present paper. It reveals that there exist 3 typical peeling force-peeling velocity relations relying on the viscous dissipation within the film and the rate-dependent extent of the interfacial adhesion. In addition to the film's viscoelasticity and the peeling velocity, the film thickness, interfacial toughness, and interfacial strength are also identified as factors that influence the steady-state peeling force. For the cohesive zone length of peeling a viscoelastic film, the analytical expression is obtained which demonstrates a dependence on peeling velocity, film viscoelasticity, film thickness, interfacial toughness, and interfacial strength. The present theoretical findings are validated by the finite element simulation and are believed to facilitate the fundamental understandings and practical applications for viscoelastic film-substrate systems.与人们熟知的弹性薄膜-基底系统的剥离行为不同,粘弹性薄膜与刚性基底粘合后的剥离行为仍不清楚。本文建立了一个理论剥离模型,假设界面相互作用为均匀分布的内聚作用,研究粘弹性薄膜的稳态剥离行为。本文主要分析了稳态剥离力和内聚区长度随速率变化的行为。结果表明,存在 3 种典型的剥离力-剥离速度关系,它们分别依赖于薄膜内部的粘滞耗散和与速率相关的界面粘附程度。除了薄膜的粘弹性和剥离速度外,薄膜厚度、界面韧性和界面强度也是影响稳态剥离力的因素。对于粘弹性薄膜剥离时的内聚区长度,得到的分析表达式表明它取决于剥离速度、薄膜粘弹性、薄膜厚度、界面韧性和界面强度。有限元模拟验证了本理论研究结果,相信有助于对粘弹性薄膜-基底系统的基本理解和实际应用。International Journal of PlasticityThe interface effect on crack nucleation under dwell fatigue loading in dual-phase Ti alloyZhang Linglei, Jiang Binbin, Qiu Jianke, Cao Xumeng, Lei Jiafeng, Yang Rui, Du Kuidoi:10.1016/j.ijplas.2023.103816 双相钛合金停留疲劳加载下裂纹成核的界面效应The microstructure of dual-phase Ti alloys crucially influences the nucleation of dwell fatigue cracks, which is of significance in determining the dwell fatigue life of Ti alloys. However, the microstructure effect on crack nucleation in dwell fatigue is still in dispute, and direct experimental investigation is desired. Here, we report that the probability of dwell fatigue cracks nucleating at grain boundaries between colonies and primary α grains is approximately one-fifth of that nucleating at grain boundaries between primary α grains. Three dislocation reaction mechanisms are determined for dislocation transmission through αs/β interfaces in colonies, two of which strongly obstruct and disperse dislocations, while the third mechanism leads to concentrated slip bands of dislocations during dwell cycle loading. As decreasing the localization of dislocation slips can effectively reduce the stress concentration at grain boundaries in colonies, it significantly decreases the possibility of crack nucleation. This demonstrates a quantitative relationship between the localization of dislocation slips and the probability of dwell-fatigue crack nucleation. The results provide insights into the quantitative analysis of the microstructure effect on crack nucleation in Ti alloys.双相钛合金的微观结构对驻留疲劳裂纹的成核有着至关重要的影响,这对决定钛合金的驻留疲劳寿命具有重要意义。然而,微观结构对驻留疲劳裂纹成核的影响仍存在争议,需要进行直接的实验研究。在此,我们报告了驻留疲劳裂纹在鲕粒和原生 α 晶粒之间的晶界成核的概率大约是原生 α 晶粒之间的晶界成核概率的五分之一。确定了位错通过菌落中的αs/β界面传输的三种位错反应机制,其中两种机制强烈阻碍和分散位错,而第三种机制则导致位错在停留循环加载期间形成集中的滑移带。由于降低位错滑移的局部性可有效减少晶胞中晶界的应力集中,从而显著降低裂纹成核的可能性。这证明了位错滑移的定位与驻留疲劳裂纹成核概率之间的定量关系。这些结果为定量分析微观结构对钛合金裂纹成核的影响提供了启示。Thin-Walled StructuresExperimental and numerical investigations towards the lateral torsional buckling of cellular steel beamsBoissonnade Nicolas, Nseir Joanna, Somja Huguesdoi:10.1016/j.tws.2023.111388对蜂窝钢梁横向扭转屈曲的实验和数值研究This paper deals with the response of so-called “cellular members” against lateral torsional buckling. These beams comprising regularly-spaced circular web openings are especially used for their high resistance-to-weight ratio, the possibility to integrate service pipes within their height, and for aesthetics. Such profiles usually exhibit a complex behaviour and many potential failure modes, including interactional local/global instability modes. Regarding global instability, the members are usually designed by means of approximate design rules, which often lead to an unduly conservative solution, with beams sometimes showing up to 150% resistance reserves. The present research works aim at improving this situation, through the development of adequate design formulae. In this respect, the present paper reports on investigations led towards improved solutions for cellular members at the experimental and numerical levels. This first paper focuses on experimental activities and on the development and validation of dedicated shell F.E. models. The results of three bending tests on members spanning from 7.5 m to 11 m are reported. Cross-sectional dimensions, material properties and accurate initial geometrical imperfections were measured for each specimen and further introduced in the corresponding F.E. models, which are shown to provide predictions in close agreement with the experimental results. The companion paper [1] further makes use of the F.E. models within extensive parametric studies and proposes a new set of design rules that could be proposed for integration in Eurocode 3.本文论述了所谓的 "蜂窝构件 "对横向扭转屈曲的响应。这些梁由间隔规则的圆形腹板开口组成,因其阻力重量比高、可在高度范围内集成服务管道以及美观而得到广泛应用。这种型材通常表现出复杂的行为和许多潜在的失效模式,包括交互式局部/整体失稳模式。在全局失稳方面,构件的设计通常采用近似设计规则,这往往会导致解决方案过于保守,梁的抗力储备有时高达 150%。目前的研究工作旨在通过开发适当的设计公式来改善这种状况。在这方面,本文报告了为改进蜂窝构件的解决方案而进行的实验和数值研究。第一篇论文侧重于实验活动以及专用壳体 F.E. 模型的开发和验证。报告了对跨度为 7.5 米至 11 米的构件进行的三次弯曲试验的结果。对每个试样的横截面尺寸、材料特性和精确的初始几何缺陷进行了测量,并将其进一步引入相应的有限元模型,结果表明,这些模型提供的预测结果与实验结果非常吻合。相关论文[1]进一步在广泛的参数研究中使用了 F.E. 模型,并提出了一套新的设计规则,这些规则可纳入欧洲规范 3。On the coupling of data-driven computing and model-driven computing with CUF-based beam modelsHui Yanchuan, Giunta Gaetano, Liu Xiao, Zheng Jie, Yang Jie, Huang Wei, Carrera Erasmodoi:10.1016/j.tws.2023.111394关于数据驱动计算和模型驱动计算与基于 CUF 的波束模型的耦合In this article, Model-driven (MD) computing and Data-driven (DD) computing mechanics are coupled under the framework of Carrera’s Unified Formulation (CUF) for beam structures A DD CUF-based computing is applied for the sub-domains of the beam under investigation where the material constitutive models are challenging to be obtained, whereas a MD CUF-based computing is used to deal with the remaining sub-domains where a constitutive model is available. By using CUF, under the premise of sufficient accuracy, the computational cost of DD-MD CUF-based models could be reduced compared with DD-MD FEM models where solid elements are used. Several static cases are analysed to demonstrate the accuracy and reliability of the proposed DD-MD CUF-based model by comparing the obtained results with those from the finite element commercial software tools.在本文中,模型驱动(MD)计算和数据驱动(DD)计算力学在卡雷拉统一公式(CUF)的框架下对梁结构进行了耦合。通过使用 CUF,在足够精确的前提下,与使用实体元素的 DD-MD FEM 模型相比,基于 DD-MD CUF 模型的计算成本可以降低。我们分析了几个静态案例,通过将获得的结果与有限元商业软件工具的结果进行比较,证明了所提出的基于 DD-MD CUF 的模型的准确性和可靠性。Damage analysis of deployable thin-walled composite shell structure during coiling upChang Zhongliang, Zhao Peng, Zhang Zhijun, Zou Guangping, Zhao Pengyuan, Wu Chenchendoi:10.1016/j.tws.2023.111395 可展开薄壁复合材料壳体结构在卷绕过程中的损伤分析Thin-walled coilable composite shells have been successfully used in deployable space payloads due to their high storage efficiency and stiffness-to-weight ratio. However, in real-life applications the deployable composite shells requiring repeatable coiling up and deployment are easy to be damaged, and their damage or failure behaviors due to large deformations has been rarely studied. This paper aims to investigate their damage and failure behaviors during the snap through, equal-sense and opposite-sense coiling up. First, multiscale models are established to compute the mechanical properties of plain-woven fabrics and unidirectional prepregs with consideration of stiffness reduction of the composites. Then, damages of each ply within the thin-walled shell are studied during snap through and coiling up. Simultaneously, effects of hub diameter on the damage of the thin-walled shell were investigated, followed by experimental verification using strain gauges and a scanning electron microscope (SEM). Simulation and experimental results show that the dominated damage of the thin-walled shell is failure of matrix. The SEMs of the edge damaged show failures of both resin and carbon fibers. Tensile damages of matrix can be relieved as the increment of the hub diameter, and no obvious failure is observed at the hub diameter of 50 mm.薄壁可卷绕复合材料壳体具有较高的存储效率和刚度重量比,已成功用于可展开的空间有效载荷。然而,在实际应用中,需要可重复卷绕和展开的可展开复合材料壳体很容易损坏,而对其因大变形而导致的损坏或失效行为的研究却很少。本文旨在研究其在扣穿、等义和反义卷绕过程中的损伤和失效行为。首先,在考虑降低复合材料刚度的情况下,建立多尺度模型来计算平织织物和单向预浸料的力学性能。然后,研究了薄壁壳体内各层在卡入和卷起过程中的损坏情况。同时,研究了轮毂直径对薄壁外壳损坏的影响,并使用应变仪和扫描电子显微镜(SEM)进行了实验验证。模拟和实验结果表明,薄壁外壳的主要损伤是基体的破坏。边缘损坏处的扫描电子显微镜显示树脂和碳纤维都发生了破坏。基体的拉伸损伤可随着轮毂直径的增大而缓解,在轮毂直径为 50 毫米时未观察到明显的破坏。A dimensionless analytical analysis for buckling and lateral buckling interaction of thin-walled beams with open cross sectionsBakhach Zaenab, Kaimbillah Ahmed El, Hamdaoui Abdellah, Braikat Bouazza, Mohri Foudil, Damil Noureddinedoi:10.1016/j.tws.2023.111396开放截面薄壁梁屈曲和侧向屈曲相互作用的无量纲分析This paper investigates the interaction between buckling and lateral buckling of thin-walled beams with arbitrary open cross-section using nonlinear modeling in large rotation and with warping. First, the equilibrium equations have been transformed into dimensionless ones, and within a nonlinear stability model, various dimensionless parameters are introduced to control the interaction between buckling and lateral buckling. In comparison to a reference of literature, this work focuses on the case of arbitrary sections and includes a greater number of higher-order terms in our analysis. These additions have an impact on the coefficients of the stability formula by expanding its applicability to non- symmetric sections. Then, the effect of the different dimensionless parameters, thus introduced on the stability curve, has been studied. The proposed solutions are validated and compared to numerical solutions obtained by a general finite element package including the warping developed by the authors using Asymptotic Numerical Method (ANM) to solve the initial nonlinear equations.本文利用非线性模型研究了任意开截面薄壁梁在大旋转和翘曲情况下屈曲与侧向屈曲之间的相互作用。首先,将平衡方程转化为无量纲方程,并在非线性稳定性模型中引入各种无量纲参数来控制屈曲和侧向屈曲之间的相互作用。与参考文献相比,本研究侧重于任意截面的情况,并在分析中加入了更多的高阶项。这些新增项扩大了稳定性公式对非对称截面的适用范围,从而对公式系数产生了影响。然后,研究了由此引入的不同无量纲参数对稳定性曲线的影响。提出的解决方案得到了验证,并与作者使用渐近数值法(ANM)求解初始非线性方程的通用有限元软件包(包括翘曲)获得的数值解决方案进行了比较。A novel non-contact measurement strategy for large-size inflatable structures based on numerical predictionsGao Weinan, Song Bo, Chen Xueyan, Lin Guochang, Tan Huifengdoi:10.1016/j.tws.2023.111397基于数值预测的新型大尺寸充气结构非接触测量战略The deformation characteristics of expansive inflatable structures, like airships, provide essential data for their operation in the stratosphere. However, due to rapid configuration changes in these structures with fluctuating air pressure, obtaining accurate morphological data quickly during testing can be challenging. This paper presents a precise method for predicting deformation in large-scale inflatable structures. A finite element method was employed to meticulously model the inflatable structure, underpinned by an inflatable ring skeleton support, and predict its potential maximum deformation points. Leveraging this predictive model as a guide, we proposed utilizing a laser scanning technique for non-contact measurements of the anticipated maximum deformation sites, aiming to discern the deformation patterns of the structure under varying air pressures. A good agreement between the non-contact measurement results and the numerical simulations affirms the efficiency and precision of the proposed methodology. This non-contact measurement strategy, grounded in finite element predictions, streamlines the measurement process, economizing on time and reducing complexity. Such an approach promises to be invaluable for expansive structures like airships. Furthermore, the insights derived from this non-contact method will be pivotal for anticipating the mechanical behaviors of full-scale stratospheric airships during their operations and for refining their design models.膨胀性充气结构(如飞艇)的变形特性为其在平流层中的运行提供了重要数据。然而,由于这些结构会随着气压的波动而迅速发生构型变化,因此在测试过程中快速获取准确的形态数据是一项挑战。本文提出了一种预测大型充气结构变形的精确方法。采用有限元方法对充气结构(由充气环骨架支撑)进行细致建模,并预测其潜在的最大变形点。以这一预测模型为指导,我们建议利用激光扫描技术对预计的最大变形点进行非接触式测量,以辨别结构在不同气压下的变形模式。非接触式测量结果与数值模拟结果之间的良好一致性证实了所建议方法的效率和精确性。这种以有限元预测为基础的非接触式测量策略简化了测量过程,节省了时间并降低了复杂性。这种方法对于飞艇这样的大型结构来说非常有价值。此外,从这种非接触式方法中获得的见解对于预测全尺寸平流层飞艇在运行期间的机械行为以及改进其设计模型至关重要。来源:复合材料力学仿真Composites FEM

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