今日更新:International Journal of Solids and Structures 3 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 5 篇
Hyperspace bounds on mixed mode elastic constants of n-component transversely-isotropic unidirectional materials
Pham Duc-Chinh
doi:10.1016/j.ijsolstr.2023.112584
n 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 nonlinearity
Zhou Chao, Gong Guangping, Chen Liang, Wang Bo, Li Rui
doi: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 system
Yin Hanbin, Ma Yinji, Feng Xue
doi: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。
The interface effect on crack nucleation under dwell fatigue loading in dual-phase Ti alloy
Zhang Linglei, Jiang Binbin, Qiu Jianke, Cao Xumeng, Lei Jiafeng, Yang Rui, Du Kui
doi: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。
Experimental and numerical investigations towards the lateral torsional buckling of cellular steel beams
Boissonnade Nicolas, Nseir Joanna, Somja Hugues
doi: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 models
Hui Yanchuan, Giunta Gaetano, Liu Xiao, Zheng Jie, Yang Jie, Huang Wei, Carrera Erasmo
doi: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 up
Chang Zhongliang, Zhao Peng, Zhang Zhijun, Zou Guangping, Zhao Pengyuan, Wu Chenchen
doi: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 sections
Bakhach Zaenab, Kaimbillah Ahmed El, Hamdaoui Abdellah, Braikat Bouazza, Mohri Foudil, Damil Noureddine
doi: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 predictions
Gao Weinan, Song Bo, Chen Xueyan, Lin Guochang, Tan Huifeng
doi: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。