今日更新:Mechanics of Materials 1 篇,Thin-Walled Structures 5 篇
Failure mechanisms at the Li anode/solid electrolyte interface during Li stripping
S.S. Shishvan, N.A. Fleck, R.M. McMeeking, V.S. Deshpande
doi:10.1016/j.mechmat.2024.104990
锂剥离过程中锂离子阳极/固体电解质界面的失效机制
A precipitous increase in the resistance of the Li metal/solid electrolyte interface can occur during the stripping of Li from the electrode. This electrical failure has been typically attributed to the loss of contact associated with the growth of voids in the Li anode at the electrode/electrolyte interface. We first analyse the growth of voids at the electrode/electrolyte interface using a framework that couples the power-law creep deformation of the Li electrode and the flux of L i + through a single-ion conductor solid electrolyte. We show that a modified Butler-Volmer kinetics where the local interfacial resistance decreases due to dislocations within the creeping Li predicts that voids indeed grow around interfacial sub-micron impurity particles. Consistent with observations that the increase in resistance of interface occurs earlier for thinner electrodes, we predict that the propensity of void growth increases with decreasing electrode thickness, and this is associated with the mechanical constraint imposed by the current collector. However, in contrast to the observations and rather counterintuitively, this analysis predicts that the cell voltage decreases with void growth. Consequently, we investigate an alternative mechanism of contact loss due to the deposition of insulating solute atoms within the Li electrode onto the interface. Predictions of the rising cell voltage using this analysis are in broad agreement with measurements. This leads us to hypothesize that although void growth occurs at the interface it is not the primary mechanism leading to the increase in interface resistance during stripping.
在电极剥离锂的过程中,锂金属/固体电解质界面的电阻会急剧增加。这种电气失效通常归因于电极/电解质界面上锂阳极空隙的增长导致的接触损失。我们首先利用锂电极的幂律蠕变变形与通过单离子导体固体电解质的 L i + 通量的耦合框架来分析电极/电解质界面空隙的生长。我们的研究表明,根据修正的巴特勒-沃尔默动力学,蠕变锂电极内部的位错会导致局部界面电阻减小,因此可以预测界面亚微米杂质颗粒周围确实会出现空隙。与电极越薄界面电阻越早增加的观察结果一致,我们预测空隙生长的倾向会随着电极厚度的减小而增加,这与集流器施加的机械约束有关。然而,与观察结果相反的是,这一分析预测电池电压会随着空洞的增加而降低,这与直觉相反。因此,我们研究了由于锂电极内的绝缘溶质原子沉积到界面上而导致接触损失的另一种机制。利用这种分析方法对电池电压上升的预测与测量结果基本一致。由此我们推测,虽然界面上会出现空隙增长,但这并不是导致剥离过程中界面电阻增加的主要机制。
Global buckling and resistances of austenitic stainless steel semi-oval hollow section beam-columns
Shuai Li, Tong Guo, Ou Zhao
doi:10.1016/j.tws.2024.111851
奥氏体不锈钢半椭圆空心截面梁柱的整体屈曲和抗力
As advanced manufacturing technologies become increasingly mature in civil engineering, novel tubular sections, characterised by appealing architectural appearance and prominent structural efficiency, can be fabricated, with an example being semi-oval hollow section. The present paper reports an experimental and numerical investigation into the global buckling behaviour and resistances of austenitic stainless steel semi-oval hollow section beam-columns under combined compression and bending. An experimental programme was firstly performed on ten austenitic stainless steel semi-oval hollow section beam-column specimens and included initial geometric imperfection measurements and eccentric compression tests. The obtained test failure loads, load–mid-height lateral deflection curves and failure modes were fully reported. Following the experimental programme, a numerical modelling programme was conducted, including validation studies to validate developed finite element models against the test results and parametric studies to generate additional numerical data. Given that the existing European code and American specification do not cover the design of stainless steel semi-oval hollow section components, the applicability of the codified design interaction curves for austenitic stainless steel circular hollow section beam-columns to their semi-oval hollow section counterparts was evaluated based on the obtained test and numerical data. The European code was found to result in relatively accurate and consistent resistance predictions for austenitic stainless steel semi-oval hollow section beam-columns with Class 1 and 2 cross-sections, but the resistance predictions for those with Class 3 cross-sections were conservative and scattered. The American specification was shown to offer overall accurate and consistent resistance predictions, but some resistance predictions were marginally unsafe.
随着先进制造技术在土木工程领域的日益成熟,可以制造出具有迷人建筑外观和突出结构效率的新型管状截面,半椭圆形空心截面就是一个例子。本文对奥氏体不锈钢半椭圆形空心截面梁柱在压缩和弯曲联合作用下的整体屈曲行为和阻力进行了实验和数值研究。首先对十个奥氏体不锈钢半椭圆空心截面梁柱试样进行了实验,包括初始几何缺陷测量和偏心压缩试验。试验中获得的失效载荷、载荷-中高侧向挠度曲线和失效模式得到了全面报告。实验计划结束后,进行了数值建模计划,包括根据测试结果验证开发的有限元模型的验证研究,以及生成更多数值数据的参数研究。鉴于现有的欧洲规范和美国规范并不涵盖不锈钢半椭圆形空心截面组件的设计,因此根据获得的测试和数值数据,对奥氏体不锈钢圆形空心截面梁柱的编纂设计交互曲线对其半椭圆形空心截面组件的适用性进行了评估。结果发现,欧洲规范对 1 级和 2 级截面的奥氏体不锈钢半椭圆形空心截面梁柱的阻力预测相对准确且一致,但对 3 级截面的梁柱的阻力预测则保守且分散。美国规范的阻力预测总体准确、一致,但某些阻力预测略显不安全。
Modeling and free vibration analysis of bolted composite flanged cylindrical-cylindrical shells under partial bolt loosening conditions
Honghao Liu, Wei Sun, Xiaofeng Liu, Hongwei Ma, Dongxu Du, Hui Li
doi:10.1016/j.tws.2024.111853
部分螺栓松动条件下螺栓连接复合法兰圆柱-圆柱壳体的建模和自由振动分析
The bolted composite coupled cylindrical shell is a common substructure in modern engineering, which may encounter the issue of local loosening conditions during service. Meanwhile, the influence of flanges on the structural vibration characteristics is often overlooked in dynamic numerical analysis. In this paper, a semi-analytical dynamic model for the bolted composite flanged cylindrical-cylindrical shell structure under arbitrary connection conditions is established, and the free vibration characteristics of locally loose structures are emphatically studied. In the model, the annular plate modeling method is developed to achieve the simulation of the flange part. To fully reflect the connection characteristics of the bolted joint, a spring surface model and the corresponding parameter determination method based on fractal contact theory are developed. The equations of motion of the structure are obtained utilizing the Lagrange equations. The accuracy of the model and its predictive ability for the vibration characteristics of the bolted composite flanged cylindrical-cylindrical shell under local loosening conditions are fully demonstrated through numerous comparisons with experimental results from other literature and modal test results obtained under various working conditions. Furthermore, the influence of the number and degree of loosening bolts on the free vibration characteristics of the structure and the coupling phenomenon between different modes are discussed. The research in this paper is expected to provide references for the design of bolted composite flanged cylindrical shell structures and the monitoring of bolt connection defects.
螺栓连接的复合耦合圆柱壳体是现代工程中常见的下部结构,在使用过程中可能会遇到局部松动的问题。同时,在动态数值分析中,法兰对结构振动特性的影响往往被忽视。本文建立了任意连接条件下螺栓复合法兰圆柱-圆柱壳体结构的半解析动力学模型,重点研究了局部松动结构的自由振动特性。在该模型中,开发了环形板建模方法来实现法兰部分的模拟。为充分反映螺栓连接的连接特性,建立了基于分形接触理论的弹簧面模型和相应的参数确定方法。利用拉格朗日方程获得了结构的运动方程。通过与其他文献中的实验结果和各种工况下的模态测试结果进行大量比较,充分证明了该模型的准确性及其对局部松动条件下螺栓复合法兰圆柱-圆柱壳体振动特性的预测能力。此外,还讨论了螺栓数量和松动程度对结构自由振动特性的影响以及不同模态之间的耦合现象。本文的研究有望为螺栓连接复合法兰圆柱壳结构的设计和螺栓连接缺陷的监测提供参考。
In-plane bidirectional dynamic crushing behaviors of a novel misplaced reinforced honeycomb
Junwei Pan, Qian Zhang, Meng Li, Jianguo Cai
doi:10.1016/j.tws.2024.111856
新型错位强化蜂窝材料的平面内双向动态挤压行为
Reinforced honeycomb exhibits exceptional energy dissipation capability. A misplaced design was introduced into reinforced honeycomb (RHC) in this paper, and a novel misplaced reinforced honeycomb structure was proposed (MRHC). The in-plane mechanical properties of MRHC was investigated experimentally, numerically and theoretically. MRHC possesses two plateau stresses in the two in-plane principle directions during low-velocity impact, while the RHC structure demonstrates this characteristic solely in one in-plane direction. The collapse modes and energy absorption performance of the MRHC structure under various impact velocities were investigated. The plateau stress behavior of the MRHC structure was investigated under various unit rotation angles. The two plateau stresses of the MRHC structure exhibit higher values when compared to the previously proposed structure with two plateau stresses. The structures exhibiting two-stage deformation characteristics can determine the extent of collision damage by analyzing the transformation of their structural configuration, establishing a foundation for the design of intelligent structures.
增强蜂窝具有卓越的消能能力。本文将错位设计引入增强蜂窝(RHC),并提出了一种新型错位增强蜂窝结构(MRHC)。实验、数值和理论研究了 MRHC 的平面力学性能。在低速冲击过程中,MRHC 在两个面内原理方向上具有两个高原应力,而 RHC 结构仅在一个面内方向上表现出这一特性。研究了 MRHC 结构在不同冲击速度下的坍塌模式和能量吸收性能。研究了不同单位旋转角度下 MRHC 结构的高原应力行为。与之前提出的具有两个高原应力的结构相比,MRHC 结构的两个高原应力值更高。表现出两阶段变形特征的结构可通过分析其结构配置的变化来确定碰撞损坏的程度,为智能结构的设计奠定了基础。
Theoretical modeling and vibration analysis of composite laminated wing-box structures of hydrogen-electric aircraft under hygrothermal environment
Xuyuan Song, Wenrui Zhao, Jian Zang, Zhen Zhang, Yewei Zhang
doi:10.1016/j.tws.2024.111854
湿热环境下氢电飞机复合材料层叠翼盒结构的理论建模与振动分析
For the sake of achieving the goal of ultra-low or even zero carbon emissions during flight, hydrogen-electric aircraft has been receiving increasing emphasis. Nevertheless, the hydrogen-electric aircraft owns an all-composite fuselage configuration and is subjected hygrothermal environment, which have a significant effect on the aircraft dynamics, especially for wing structure. In this study, an improved orthogonal polynomial solution based on the Rayleigh-Ritz method is developed for the dynamic analysis of composite laminated wing-box structures (CLWBSs) of hydrogen-electric aircraft with humid and hot environment and elastic boundary. In this solution approach, the potential energy, kinetic energy, elastic potential energy and hygrothermal potential energy of CLWBSs are derived from the framework of Kirchhoff thin plate hypothesis. A set of artificial springs is imported to the free edges of CLWBSs to simulate the elastic boundary and connection between two plates. The convergence, accuracy and computational efficiency of the proposed formulation are validated by experiment and finite element analysis. The effect of the coupling parameters and the elastic boundaries due to flexible composite fuselage in hygrothermal environment created by the hydrogen fuel cells are systematically investigated which have been confirmed by theoretical research, finite element analysis and experiment. The related findings indicate that the present approach provided an effective formulation for the vibration analysis and optimization of flexible composite wing-box structures. It can be applied in the field of aerospace and navigation industry at the same time.
为了实现飞行过程中超低甚至零碳排放的目标,氢电动飞机越来越受到重视。然而,由于氢电动飞机采用全复合材料机身结构,且受湿热环境影响较大,对飞机动力学,尤其是机翼结构影响较大。本研究针对氢电动飞机复合材料层压翼盒结构(CLWBS)在湿热环境和弹性边界下的动力学分析,提出了一种基于 Rayleigh-Ritz 方法的改进正交多项式求解方法。在这种求解方法中,CLWBS 的势能、动能、弹性势能和湿热势能都是从基尔霍夫薄板假说的框架中推导出来的。在 CLWBS 的自由边缘导入一组人工弹簧,以模拟两板之间的弹性边界和连接。实验和有限元分析验证了所提公式的收敛性、准确性和计算效率。通过理论研究、有限元分析和实验,系统地研究了氢燃料电池产生的湿热环境中柔性复合材料机身的耦合参数和弹性边界的影响。相关研究结果表明,本方法为柔性复合材料机翼箱体结构的振动分析和优化提供了有效的公式。该方法可同时应用于航空航天和航海工业领域。
Adjusting Dynamic and Damping Performance in Fiber-Reinforced Magnetorheological Elastomer Composite Conical Shells Subjected to Compressive Loads
Yunhe Zou, Shufeng Tang, Shijie Guo, Xiaodong He, Xianjuan Song, Xiaowen Song, Artin Hozuri
doi:10.1016/j.tws.2024.111855
调整承受压缩载荷的纤维增强磁流变弹性体复合锥形壳体的动态和阻尼性能
This study explores the dynamic behavior of axially loaded conical shells composed of magnetorheological elastomer composites (MRECs). The investigation focuses on analyzing the impact of compressive loads on the frequencies and loss factors of these composites. The MRECs consist of laminates reinforced with fibers, enabling tunable viscoelastic properties through the utilization of magnetic fields. The equivalent mechanical characteristics of the MREC are calculated using the modified Voigt and Halpin-Tsai micromechanical rules. By employing the first-order shear deformation theory and Sanders-based strains, the kinematics of the conical shell are accurately modeled. A semi-analytical analysis, combining trigonometric expansion and the generalized differential quadrature (GDQ) methods, is employed to solve the system's highly coupled partial differential equations. Two consecutive analyses are performed. Firstly, the critical buckling load of the MREC conical shell is obtained through a stability analysis. Subsequently, the frequencies and loss factors of the shell in the pre-buckling zone are computed. Parametric analyses are conducted to study the impact of key factors, including magnetic field strength, compressive load magnitude, composite properties, geometric parameters, and boundary conditions. The proposed methodology is rigorously validated through meticulous accuracy and convergence analysis. The outcomes provide valuable insights into the dynamic response of axially loaded magnetorheological elastomer composite conical shells, highlighting their potential in adjustable dynamic and damping systems.
本研究探讨了由磁流变弹性体复合材料(MREC)构成的轴向加载锥形壳体的动态行为。研究重点是分析压缩载荷对这些复合材料的频率和损耗因子的影响。磁流变弹性体复合材料由纤维增强的层压板组成,通过利用磁场实现可调的粘弹性能。MREC 的等效机械特性是利用改进的 Voigt 和 Halpin-Tsai 微机械规则计算得出的。通过采用一阶剪切变形理论和基于桑德斯的应变,对锥形外壳的运动学进行了精确建模。结合三角展开和广义微分正交(GDQ)方法的半解析分析被用来求解系统的高度耦合偏微分方程。连续进行了两次分析。首先,通过稳定性分析得出 MREC 锥壳的临界屈曲载荷。随后,计算壳体在预屈曲区的频率和损耗因子。通过参数分析,研究了磁场强度、压缩载荷大小、复合材料特性、几何参数和边界条件等关键因素的影响。通过细致的精度和收敛性分析,对所提出的方法进行了严格验证。研究结果为轴向加载磁流变弹性体复合锥形壳的动态响应提供了宝贵的见解,凸显了其在可调动态和阻尼系统中的潜力。