今日更新:International Journal of Solids and Structures 3 篇,Mechanics of Materials 1 篇,Thin-Walled Structures 1 篇
Thin shells reinforced by fibers with intrinsic flexural and torsional elasticity
Steigmann David J., Bîrsan Mircea, Shirani Milad
doi:10.1016/j.ijsolstr.2023.112550
具有内在弯曲和扭转弹性的纤维增强薄壳
A two-dimensional thin shell model, derived from a three-dimensional Cosserat elasticity theory for fiber-reinforced solids, is presented. Models for single laminae and two-ply laminates are derived. The novelty of these models lies in the assignment of intrinsic flexural and torsional elasticity to the embedded fibers, regarded as continuously distributed material curves.
介绍了一种二维薄壳模型,该模型源自纤维增强固体的三维 Cosserat 弹性理论。推导出了单层板和双层板的模型。这些模型的新颖之处在于将固有的弯曲和扭转弹性分配给嵌入的纤维,并将其视为连续分布的材料曲线。
A novel computational multi-scale modeling of randomly-distributed-graphene/epoxy nanocompfvosites with interfacial interactions
ÇALIŞKAN Umut, GULSEN Hilal
doi:10.1016/j.ijsolstr.2023.112553
具有界面相互作用的随机分布石墨烯/环氧纳米复合材料的新型多尺度计算模型
This article introduces a novel multi-scale modeling methodology that incorporates randomly distributed graphene/epoxy nanocomposites, accounting for interfacial interactions. The objective is to forecast the elastic characteristics and mechanical performance of nanocomposites reinforced with single-layer graphene. We developed a new multi-scale scheme by randomly distributing the triple-structure formed by graphene, interface material and their Van Der Walls interactions in epoxy with an improved algorithm by using the finite element method. The number of single-layer graphene affecting the random distribution method and the volume fraction of nanocomposites were investigated. A developed methodology was proposed for producing graphene-VanDerWalls interactions-interface structures, avoiding overlapping desired geometric dimensions and numbers in a representative control volume and determining random positions. In order to model Van Der Walls interactions between graphene and interface material atoms by finite element method and to apply them to randomly distributed graphene, a different algorithm was required. Performing numerical analyzes of graphene nanoparticles by embedding them into epoxy with the real dimensions is not an appropriate task today. In particular, it is impossible to analyze these real graphene nanoparticles as multiple by randomly distributing them in epoxy. Therefore, in this research, a new approach has been developed to overcome this problem. The result of the model is in acceptable agreement with the result of conducted experimental results from the literature.
本文介绍了一种新颖的多尺度建模方法,其中包含随机分布的石墨烯/环氧纳米复合材料,并考虑了界面相互作用。目的是预测用单层石墨烯增强的纳米复合材料的弹性特性和机械性能。我们开发了一种新的多尺度方案,将石墨烯、界面材料及其范德瓦斯相互作用形成的三重结构随机分布在环氧树脂中,并使用有限元法改进了算法。研究了影响随机分布方法的单层石墨烯数量和纳米复合材料的体积分数。提出了一种用于制造石墨烯-范德瓦尔斯相互作用界面结构的方法,避免在代表性控制体积中重叠所需的几何尺寸和数量,并确定随机位置。为了用有限元法模拟石墨烯与界面材料原子之间的范德瓦尔斯相互作用,并将其应用于随机分布的石墨烯,需要一种不同的算法。通过将石墨烯纳米颗粒嵌入具有实际尺寸的环氧树脂中来对其进行数值分析并不是一项合适的任务。特别是,将这些真实的石墨烯纳米粒子随机分布在环氧树脂中,不可能对其进行多重分析。因此,本研究开发了一种新方法来克服这一问题。该模型的结果与文献中的实验结果一致。
Edge effect and indentation depth-dependent contact behavior in contact of an elastic quarter-space
Li Qiang
doi:10.1016/j.ijsolstr.2023.112552
弹性四分之一空间接触中的边缘效应和随压痕深度变化的接触行为
The edge effect in contact of an elastic quarter-space is numerically studied in this work. The extension of Hetényi’s approach of overlapping two elastic half-spaces is implemented in the boundary element method to obtain the solution of an elastic quarter-space whose top and side surfaces could be both loaded. In the study on the indentation test of a rigid sphere on an elastic quarter-space, the dependencies of the normal force, mean contact radius, and pressure distribution in contact area as well as the internal von Mises stress in relation to the position of the sphere from the side edge are obtained numerically and expressed by fitting the numerical results. These equations can be also used to interpret the indentation depth-dependent contact behavior: from Hertzian contact at the beginning of the indentation to the non-circular contact at large indentation depth. In addition, the results are compared with a contact case of a quarter-space in which the side surface of the quarter-space is not completely free: shear stresses on the side surface vanish but normal stress exists. The latter case generates very similar results, especially the contact area, but its solutions are much easier to achieve by applying a symmetrical loading on an elastic half-space, offering an effective way to approximate the solution of a quarter-space.
本研究对弹性四分之一空间接触中的边缘效应进行了数值研究。在边界元方法中实现了 Hetényi 方法的扩展,即重叠两个弹性半空间,从而获得了顶面和侧面均可受力的弹性四分之一空间的解。在研究刚性球体在弹性四分之一空间上的压痕试验时,通过拟合数值结果得到了法向力、平均接触半径、接触面积上的压力分布以及内部 von Mises 应力与球体从侧边开始的位置的相关性。这些方程还可用于解释与压痕深度相关的接触行为:从压痕开始时的赫兹接触到大压痕深度时的非圆形接触。此外,还将结果与四分之一空间的接触情况进行了比较,其中四分之一空间的侧表面并非完全自由:侧表面的剪应力消失,但存在法向应力。后一种情况产生的结果非常相似,尤其是接触面积,但通过在弹性半空间上施加对称载荷,其解法更容易实现,为近似四分之一空间的解法提供了有效途径。
Phase field modeling of thermal fatigue crack growth in elastoplastic solids and experimental verification
Du Chenyu, Cui Haitao, Zhang Hongjian, Cai Zhibin, Zhai Weikuo
doi:10.1016/j.mechmat.2023.104839
弹塑性固体热疲劳裂纹生长的相场建模与实验验证
It is challenging to simulate thermal fatigue crack growth in elastoplastic solids, meanwhile, the phase field model is very attractive for simulating complex cracking problems. A thermal-elastoplastic phase field model for thermal fatigue was developed, and its accuracy and availability were verified by typical examples. Then a verified thermal fatigue experiment of the V-notch specimen was carried out and the crack growth was simulated based on the phase field model. The results indicate that the process of thermal fatigue crack in elastoplastic solids from initiation to propagation is effectively simulated by the proposed phase field model. As the regularization length increases, the simulated crack has a longer length and stronger diffusivity. The appropriate regularization length needs to be determined based on experimental results.
在弹塑性固体中模拟热疲劳裂纹生长具有挑战性,而相场模型对于模拟复杂的裂纹问题非常有吸引力。本文建立了热疲劳弹塑性相场模型,并通过典型实例验证了该模型的准确性和可用性。然后对 V 型缺口试样进行了验证性热疲劳实验,并根据相场模型模拟了裂纹的生长过程。结果表明,所提出的相场模型能有效模拟弹塑性固体中热疲劳裂纹从产生到扩展的过程。随着正则化长度的增加,模拟裂纹的长度更长,扩散性更强。需要根据实验结果确定合适的正则化长度。
Exploring guided wave propagation in composite cylindrical shells with an embedded delamination through refined spectral element method
Hua Fenfei, You Qingquan, Huang Qingyang, Fu Wanbiao, Zhou Xiaoqiang
doi:10.1016/j.tws.2023.111326
通过精炼谱元法探索嵌入分层的复合圆柱壳中的导波传播
The elastic wave propagation in a thin-walled composite structure carries information concerning its material properties and structural discontinuities. Towards the damage identification, a refined spectral element method (SEM) is presented to explore the guided wave propagation in composite cylindrical shells with embedded delamination. The governing equations and the natural boundary conditions are derived using the first-order shear deformation theory along with the Hamilton's principle. The spectral shell element is established via the exact strong-form solutions, and the dynamic stiffness matrix is formulated through the force-displacement relations. Transforming the wave differential equations into the frequency domain, the numerical Laplace transform is applied to solve the inverse problems. Following a sub-laminate approach, the delamination is modeled by means of four spectral elements and the interface continuity conditions. In addition, the stiffness reduction method is introduced to approximate the delamination. A comparison with published results in terms of the natural frequencies is made to verify the accuracy of the SEM. The dispersion characteristics of the cylindrical shell are examined including the wave number, phase and group velocities. The interaction of guided waves with the delamination is revealed. The influences of the length, depth, and position of the delamination on the wave responses are demonstrated.
薄壁复合材料结构中的弹性波传播蕴含着有关其材料特性和结构不连续性的信息。为了进行损伤识别,本文提出了一种改进的谱元法 (SEM),用于探索具有嵌入分层的复合材料圆柱壳中的导波传播。利用一阶剪切变形理论和汉密尔顿原理推导出治理方程和自然边界条件。通过精确的强形式解建立了频谱壳元素,并通过力-位移关系制定了动态刚度矩阵。将波微分方程转换到频域,应用数值拉普拉斯变换解决逆问题。采用子层压方法,通过四个频谱元素和界面连续性条件对分层进行建模。此外,还引入了刚度减小法来近似分层。与已公布的自然频率结果进行了比较,以验证 SEM 的准确性。研究了圆柱形壳体的频散特性,包括波数、相位和群速度。揭示了导波与分层的相互作用。演示了分层的长度、深度和位置对波响应的影响。