【新文速递】2024年5月10日固体力学SCI期刊最新文章_ACT_Mechanical_Additive_System_Marc_静力学_断裂_非线性_多孔介质_通用_增材_离散元_裂纹_BIM_理论

【新文速递】2024年5月12日固体力学SCI期刊最新文章

今日更新：Journal of the Mechanics and Physics of Solids 4 篇Journal of the Mechanics and Physics of SolidsThe poker-chip experiments of synthetic elastomers explainedFarhad Kamarei, Aditya Kumar, Oscar Lopez-Pamiesdoi:10.1016/j.jmps.2024.105683解释了合成弹性体的扑克筹码实验In a recent study, Kumar and Lopez-Pamies (J. Mech. Phys. Solids 150: 104359, 2021) have provided a complete quantitative explanation of the famed poker-chip experiments of Gent and Lindley (Proc. R. Soc. Lond. Ser. A 249: 195–205, 1959) on natural rubber. In a nutshell, making use of the fracture theory of Kumar, Francfort, and Lopez-Pamies (J. Mech. Phys. Solids 112: 523–551, 2018), they have shown that the nucleation of cracks in poker-chip experiments in natural rubber is governed by the strength — in particular, the hydrostatic strength — of the rubber, while the propagation of the nucleated cracks is governed by the Griffith competition between the bulk elastic energy of the rubber and its intrinsic fracture energy. The main objective of this paper is to extend the theoretical study of the poker-chip experiment by Kumar and Lopez-Pamies to synthetic elastomers that, as opposed to natural rubber: ( i ) may feature a hydrostatic strength that is larger than their uniaxial and biaxial tensile strengths and ( i i ) do not typically exhibit strain-induced crystallization. A parametric study, together with direct comparisons with recent poker-chip experiments on a silicone elastomer, show that these two different material characteristics have a profound impact on where and when cracks nucleate, as well as on where and when they propagate. In conjunction with the results put forth earlier for natural rubber, the results presented in this paper provide a complete description and explanation of the poker-chip experiments of elastomers at large. As a second objective, this paper also introduces a new fully explicit constitutive prescription for the driving force that describes the material strength in the fracture theory of Kumar, Francfort, and Lopez-Pamies.在最近的一项研究中，库马尔和洛佩兹-帕米斯(J. Mech。理论物理。固体150:104359,2021)为Gent和Lindley (Proc. R. Soc)著名的扑克芯片实验提供了完整的定量解释。Lond。爵士。橡胶学报(英文版)249:195-205,1959)。简而言之，利用Kumar, Francfort, and Lopez-Pamies (J. Mech.)的断裂理论。理论物理。固体112:523-551,2018)，他们已经表明，在天然橡胶的扑克屑实验中，裂纹的成核是由橡胶的强度(特别是静水强度)决定的，而成核裂纹的扩展是由橡胶的体积弹性能与其固有断裂能之间的格里菲斯竞争决定的。本文的主要目的是将Kumar和Lopez-Pamies的扑克牌片实验的理论研究扩展到合成弹性体，与天然橡胶相反:(i)合成弹性体的静水强度可能大于其单轴和双轴拉伸强度，(i)合成弹性体通常不会表现出应变诱导结晶。一项参数化研究，以及与最近在硅胶弹性体上进行的扑克片实验的直接比较，表明这两种不同的材料特性对裂纹在何时何地成核以及裂纹在何时何地扩散有着深远的影响。结合先前对天然橡胶的实验结果，本文的结果对弹性体的扑克牌切片实验提供了完整的描述和解释。作为第二个目标，本文还介绍了Kumar、Francfort和Lopez-Pamies断裂理论中描述材料强度的驱动力的一个新的完全明确的本构公式。Optimal surface clothing with elastic netsD. Andrini, M. Magri, P. Ciarlettadoi:10.1016/j.jmps.2024.105684带弹性网的最佳表面服装The clothing problem aims at identifying the shape of a planar fabric for covering a target surface in the three-dimensional space. It poses significant challenges in various applications, ranging from fashion industry to digital manufacturing. Here, we propose a novel inverse design approach to the elastic clothing problem that is formulated as a constrained optimization problem. We assume that the textile behaves as an orthotropic, nonlinear elastic surface with fibers distributed along its warp and weft threads, and we enforce mechanical equilibrium as a variational problem. The target surface is frictionless, except at its boundary where the textile is pinned, imposing a unilateral obstacle condition for the reactive forces at the target surface. The constrained optimization problem also accounts for an elongation condition of the warp and weft fibers, possibly with bounded shearing angle. We numerically solve the resulting constrained optimization problem by means of a gradient descent algorithm. The numerical results are first validated against known clothing solutions for Chebyshev nets, taking the limit of inextensible fibers. We later unravel the interplay between thread and shear stiffness for driving the optimal cloth shape covering the hemisphere and the hemicatenoid. We show how the metric of these target surfaces strongly affects the resulting distribution of the reaction forces. When considering the limit of covering the full sphere, we show how clothing with elastic nets allows to avoid the onset of singularities in the corresponding Chebyshev net, by developing corners at the cloth boundary.服装问题旨在识别用于覆盖三维空间中目标表面的平面织物的形状。它在从时尚行业到数字制造的各种应用中都提出了重大挑战。在这里，我们提出了一种新的反设计方法来解决弹性服装问题，它被表述为约束优化问题。我们假设织物表现为正交各向异性的非线性弹性表面，纤维沿其经纱和纬纱分布，并将机械平衡作为变分问题来强制执行。目标表面是无摩擦的，除了织物被钉住的边界，这为目标表面的反作用力施加了单边障碍条件。约束优化问题还考虑了经纬纤维的伸长情况，可能存在有界剪切角。采用梯度下降算法对约束优化问题进行了数值求解。数值结果首先与已知的切比雪夫网的服装解进行了验证，并考虑了不可拉伸纤维的极限。我们随后揭示了纱线和剪切刚度之间的相互作用，以驱动覆盖半球和半抛物面的最佳布料形状。我们展示了这些目标表面的度规如何强烈地影响反作用力的最终分布。当考虑覆盖整个球体的极限时，我们展示了带弹性网的衣服如何通过在布料边界处发展角来避免相应的切比雪夫网中的奇点的发生。How Are Microstructural Defect Interactions Linked to Simultaneous Intergranular and Transgranular Fracture Modes in Polycrystalline Systems?Muh-Jang Chen, Nan Li, Jonathan Gigax, Abigail Hunter, S. Fensin, Mohammed A. Zikrydoi:10.1016/j.jmps.2024.105674在多晶体系中，微观结构缺陷的相互作用与同时发生的沿晶和穿晶断裂模式是如何联系在一起的?The major objective of this investigation is to fundamentally understand and predict how intergranular (IG) and transgranular (TG) fracture modes nucleate and propagate in f.c.c. polycrystalline systems due to defects, such as total and partial dislocation densities and grain boundary (GB) structures and misorientations. A dislocation density crystalline plasticity (DCP) formulation based on the evolution and interaction of total and partial dislocation densities was integrated with a recently developed fracture approach to investigate the fracture nucleation and propagation of simultaneous multiple fracture events, including both IG and TG fracture events. The aggregate grains and GB orientations and morphologies are based on EBSD measurements that are representative of polycrystalline copper aggregates with a broad range of random high angle and low angle GBs. The predictions indicate that dislocation density pileups induce IG fracture due to interrelated stress, slip, and total and partial dislocation density accumulations and interactions for both high angle GBs (HAGBs) and low angle GBs (LAGBs). TG fracture nucleation and propagation occurred due to normal stress accumulations, which exceeds the fracture stress, along cleavage planes. Furthermore, it is shown how IG cracks transition from the GB plane to the cleavage planes as cracks nucleate and propagate. Accumulated plastic zones due to different slip system activities can impede and blunt crack propagation and fronts. These plastic zones form due to high Lomer and Shockley partial dislocation densities. These predictions, which are consistent with experimental observations, provide a fundamental understanding of how simultaneous failure modes initiate and propagate for physically representative microstructures.本研究的主要目的是从根本上了解和预测由于总和部分位错密度、晶界(GB)结构和取向错误等缺陷，在氟化碳多晶体系中，沿晶(IG)和穿晶(TG)断裂模式是如何形核和扩展的。基于总位错密度和部分位错密度的演化和相互作用的位错密度结晶塑性(DCP)公式与最近发展的断裂方法相结合，研究了同时发生的多个断裂事件(包括IG和TG断裂事件)的断裂形核和扩展。聚集体晶粒和GB取向和形态基于EBSD测量，代表了具有广泛随机高角和低角GB的多晶铜聚集体。预测表明，对于高角度GBs (HAGBs)和低角度GBs (LAGBs)，由于相互关联的应力、滑移、总和部分位错密度积累和相互作用，位错密度堆积导致IG断裂。热重断裂的形核和扩展是由于沿解理面的正常应力积累超过断裂应力而发生的。此外，还显示了当裂纹形核和扩展时，IG裂纹如何从GB平面过渡到解理平面。不同滑移系统活动导致的累积塑性区会阻碍和钝化裂纹的扩展和前缘。这些塑性区是由于高洛默和肖克利部分位错密度而形成的。这些预测与实验观察结果一致，为物理上具有代表性的微观结构的同时失效模式如何启动和传播提供了基本的理解。Elastic contact between rough surfaces: Bridging the gap between theory and experimentHans Terwisscha-Dekker, Albert M. Brouwer, Bart Weber, Daniel Bonndoi:10.1016/j.jmps.2024.105676粗糙表面之间的弹性接触:弥合理论与实验之间的差距Friction is generated where solids touch, thus quantitative understanding of the microscopic contact area is crucial to predict macroscopic friction. All surfaces are rough, and typically small-scale roughness rather than macroscopic geometry sets the contact area. Rough contact theories have been developed that predict the contact area, using the surface topography and the mechanical properties of the solids as input. However, the validity of these theories remains under debate. Systematic comparison between theory and experiment has been lacking, due to the experimental difficulty to access the contact area, especially at small length scales where idealized assumptions of contact models may not hold. Here, we use a state-of-the-art fluorescence microscopy technique to directly access the contact area of a glass-glass contact with nanometric out-of-plane resolution. We systematically vary the roughness of the contact and carefully measure the surface topography across length scales. Comparison of high-resolution contact experiments to different contact theories enables us to unambigously conclude that only elastic Persson theory quantitatively describes experimental observations.摩擦是在固体接触的地方产生的，因此定量了解微观接触面积对于预测宏观摩擦是至关重要的。所有的表面都是粗糙的，通常是小尺度的粗糙而不是宏观的几何形状决定了接触面积。粗糙接触理论已经发展，预测接触面积，使用表面形貌和固体的机械性能作为输入。然而，这些理论的有效性仍然存在争议。由于实验难以接近接触区域，特别是在接触模型的理想假设可能不成立的小长度尺度上，理论和实验之间缺乏系统的比较。在这里，我们使用最先进的荧光显微镜技术，以纳米级的面外分辨率直接访问玻璃-玻璃接触区域。我们系统地改变接触的粗糙度，并仔细测量长度尺度上的表面形貌。高分辨率接触实验与不同接触理论的比较使我们能够明确地得出结论，只有弹性佩尔松理论才能定量地描述实验观察结果。来源：复合材料力学仿真Composites FEM

【新文速递】2024年5月10日固体力学SCI期刊最新文章

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【新文速递】2024年5月12日固体力学SCI期刊最新文章