【新文速递】2024年7月11日固体力学SCI期刊最新文章

 

今日更新：International Journal of Solids and Structures 1 篇，Journal of the Mechanics and Physics of Solids 2 篇，Thin-Walled Structures 2 篇

International Journal of Solids and Structures

Crack layer modeling of butt-fusion joints induced slow crack growth in high-density polyethylene pipes

Abdulla Almomani, Abdel-Hamid I. Mourad

doi:10.1016/j.ijsolstr.2024.112970

高密度聚乙烯管道中对接熔接接头诱导缓慢裂纹增长的裂纹层建模

The design and reliability of high-density polyethylene (HDPE) pipes can be dictated by the damage tolerance of their butt-fusion joints. A slow crack growth (SCG) model based on the crack layer theory for HDPE pipes internal and external circumferential and butt-fusion joints cracks is developed to investigate the discontinuous SCG behavior and lifetime tf variations. Using the developed model, the discontinuous SCG patterns, jump lengths and lifetime tf can be accurately simulated. In addition, the effects of pipes standard dimension ratio, internal pressure, and temperature on the SCG behavior and tf are investigated. Compared to pipe cracks, it was found that butt-fusion induced SCG can reduce the pipe tf > 60 %. Unlike longitudinal cracks, tf of external circumferential cracks, were found shorter than the internal ones, mandating an earlier evaluation. The new SCG model shows good accuracy with the experimental results. The same substitute geometry approach used can be followed for othercomplex designs, which aids in establishing a fundamental methodology for more realistic lifetime predictions.

高密度聚乙烯（HDPE）管道的设计和可靠性取决于其对接熔接接头的损伤容限。本文基于裂纹层理论，针对高密度聚乙烯（HDPE）管道内外圆周和对接熔接接头裂纹建立了缓慢裂纹生长（SCG）模型，以研究不连续 SCG 行为和寿命 tf 变化。利用所建立的模型，可以准确模拟不连续 SCG 模式、跳跃长度和寿命 tf。此外，还研究了管道标准尺寸比、内部压力和温度对 SCG 行为和 tf 的影响。研究发现，与管道裂缝相比，对接熔合诱发的 SCG 可使管道的 tf 降低 > 60%。与纵向裂缝不同，外部圆周裂缝的 tf 比内部裂缝短，因此需要更早地进行评估。新的 SCG 模型与实验结果显示出良好的准确性。同样的替代几何方法也可用于其他复杂的设计，这有助于为更真实的寿命预测建立基本方法。

Journal of the Mechanics and Physics of Solids

Imbibition of water into a cellulose foam: the kinetics

Ratul Das, Vikram S. Deshpande, Norman A. Fleck

doi:10.1016/j.jmps.2024.105763

水浸入纤维素泡沫：动力学

Cellulose foams are representative of many porous engineering solids that can absorb a large quantity of fluid such as water. Experiments are reported to give insight into water rise in cellulose foams and the underlying mechanisms. The water rise characteristic of water height h versus time t displays a distinct knee on a log-log plot; this knee separates an initial regime where h scales as t 1/2 from a subsequent regime where h scales as t 1/4. The rate of water rise below the knee is consistent with the Washburn law of water rise in a single dominant capillary, and the knee in the h(t) curve suggests that the Jurin height of this large capillary has been attained. Water rise in the foam above the knee of the h(t) curve is interpreted as water rise in a population of small capillaries with a wide range of radius that feed off the dominant capillary. A series of critical experiments support this interpretation, including water rise in inclined columns, and water rise from a limited reservoir of water. A simple analytical model is used to provide a physical explanation for the observations. Additionally, X-ray computer tomography is used to deduce the probability density function of the small capillaries. The experimental findings are in support of the hypothesis that water rise in the cellulose foam is driven by capillary action and not by diffusion.

纤维素泡沫是许多多孔工程固体的代表，可以吸收大量液体（如水）。本报告通过实验深入探讨了纤维素泡沫中的水上升现象及其内在机理。水高度 h 随时间 t 变化的水上升特性在对数-对数图上显示出一个明显的膝点；该膝点将 h 随 t 1/2 变化的初始状态与 h 随 t 1/4 变化的后续状态区分开来。膝点以下的水位上升速度符合单个主要毛细管中水位上升的沃什伯恩定律，而 h（t）曲线上的膝点表明，该大型毛细管的汝林高度已经达到。h(t) 曲线膝盖以上泡沫中的水上升被解释为从主要毛细管中汲取水的半径范围较大的小毛细管群中的水上升。一系列关键实验支持了这一解释，包括倾斜柱中的水上升和来自有限储水层的水上升。一个简单的分析模型为观测结果提供了物理解释。此外，还利用 X 射线计算机断层扫描来推断小毛细管的概率密度函数。实验结果支持这样的假设，即纤维素泡沫中水的上升是由毛细作用而非扩散驱动的。

Statistical mechanics of plasticity: Elucidating anomalous size-effects and emergent fractional nonlocal continuum behavior

Pratik Khandagale, Liping Liu, Pradeep Sharma

doi:10.1016/j.jmps.2024.105747

塑性统计力学：阐明异常尺寸效应和出现的分数非局部连续行为

Extensive experiments over the decades unequivocally point to a pronounced scale-dependency of plastic deformation in metals. This observation is fairly general, and broadly speaking, strengthening against deformation is observed with the decrease in the size of a relevant geometrical feature of the material, e.g., the thickness of a thin film. The classical theory of plasticity is size-independent, and this has spurred extensive research into an appropriate continuum theory to elucidate the observed side effects. This pursuit has led to the emergence of strain gradient plasticity, along with its numerous variants, as the paradigm of choice. Recognizing the constrained shear of a thin metallic film as the model problem to understand the observed size-effect, all conventional (and reasonable candidate) theories of strain gradient plasticity predict a scaling of yield strength that inversely varies with the film thickness ∼h−1. Experimental findings indicate a considerably diminished scaling, the magnitude of which can exhibit significant variation based on processing conditions or even the mode of deformation. As an example, the scaling exponent as low as −0.2 has been observed for as-deposited copper thin films. Two perspectives have been posited to explain this perplexing anomaly. Kuroda and Needleman (2019) argue that the conventional boundary conditions used in strain gradient plasticity theory are not meaningful for the canonical constrained thin film problem and propose a physically motivated alternative. Dahlberg and Ortiz (2019) contend that the intrinsic differential calculus structure of all strain gradient plasticity theories will invariably lead to the incorrect (or rather inadequate) explanation of the size-scaling. They propose a fractional strain gradient plasticity framework where the derivative fractional order is a material property that correlates with the scaling exponent. In this work, we present an alternative approach that complements the existing explanations. We create a statistical mechanics model for interacting microscopic units that deform and yield with the rules of classical plasticity, and plastic yielding is treated as a phase transition. We coarse-grain the model to precisely elucidate the microscopic interactions that can lead to the emergent size-effects observed experimentally. Specifically, we find that depending on the nature of the long-range microscopic interactions, the emergent coarse-grained theory can be of fractional differential type or alternatively a form of integral nonlocal model. Our theory, therefore, provides a partial (and microscopic) justification for the fractional derivative model and makes clear the precise microscopic interactions that must be operative for a continuum plasticity theory to be a valid phenomenological descriptor for capturing the correct scale dependency.

几十年来的大量实验明确指出，金属的塑性变形具有明显的尺度依赖性。这一观察结果具有相当的普遍性，从广义上讲，随着材料相关几何特征（如薄膜厚度）尺寸的减小，可观察到抗变形能力的增强。塑性的经典理论与尺寸无关，这促使人们广泛研究适当的连续理论，以阐明观察到的副作用。应变梯度塑性及其众多变体就是这种研究的成果。所有传统的（以及合理的候选）应变梯度塑性理论都将金属薄膜的约束剪切作为理解所观察到的尺寸效应的模型问题，并预测屈服强度的比例与薄膜厚度 ∼h-1 成反比变化。实验结果表明，这种缩放比例会大大减小，其大小会因加工条件甚至变形模式的不同而发生显著变化。例如，在沉积铜薄膜中观察到的缩放指数低至-0.2。有两种观点可以解释这种令人困惑的反常现象。Kuroda 和 Needleman（2019 年）认为，应变梯度塑性理论中使用的传统边界条件对典型约束薄膜问题没有意义，并提出了一种物理上的替代方案。Dahlberg 和 Ortiz（2019）认为，所有应变梯度塑性理论的内在微分微积分结构必然会导致对尺寸缩放的不正确（或不充分）解释。他们提出了一种分数应变梯度塑性框架，其中导数分数阶是一种与缩放指数相关的材料属性。在这项工作中，我们提出了另一种补充现有解释的方法。我们为相互作用的微观单元创建了一个统计力学模型，这些微观单元按照经典塑性规则变形和屈服，塑性屈服被视为一种相变。我们对模型进行了粗粒化处理，以精确阐明可导致实验观察到的新兴尺寸效应的微观相互作用。具体来说，我们发现，根据长程微观相互作用的性质，出现的粗粒度理论可以是分数微分类型的，也可以是积分非局部模型的一种形式。因此，我们的理论为分数导数模型提供了部分（和微观）理由，并阐明了连续可塑性理论必须具备的精确微观相互作用，才能成为捕捉正确尺度依赖性的有效现象学描述符。

Thin-Walled Structures

Unified Method for Predicting the Fatigue Life of Pipe–Sphere Joints in Grid Structures

Saicong Guo, Hanchao Liu, Xiaoling Liu, Guoqing Wang, Honggang Lei

doi:10.1016/j.tws.2024.112209

预测网格结构中管球接头疲劳寿命的统一方法

Pipe–sphere joints (PSJs), which are commonly used in grid structures, are susceptible to fatigue failure under cyclic loading caused by suspended cranes. This paper presents a unified method for predicting the fatigue life of PSJs, including the weld toes on both the pipe and sphere surfaces, based on equivalent structural stress. A decomposition and recombination fitting (DRF) method was proposed to determine the optimal functional form of stress concentration factors (SCFs). A nonlinear regression analysis was conducted on the calculated results of 61 common PSJs to obtain a semi-analytical expression for the structural stress of the weld toes. Using this unified method, the fatigue life of the weld toes on both the pipe and sphere surfaces was estimated. The results indicated that the logarithmic ratios between the predicted fatigue life and experimental results were typically 0.93–1.08 for weld toes on pipe surfaces and 0.97–1.13 for weld toes on spherical surfaces, confirming the accuracy of the method. This unified method is applicable to predict the fatigue life of PSJs of various sizes and involves concise mathematical calculations independent of finite element analysis, thereby facilitating engineering applications. The DRF method can be used as a reference for fitting SCFs to specific structures. Furthermore, this prediction method enables the identification of the failure modes in PSJs. As the size of the steel pipe increased, the fatigue failure gradually shifted from the pipe surface to the sphere surface.

网格结构中常用的管球连接（PSJ）在悬挂式起重机引起的循环载荷作用下容易发生疲劳破坏。本文提出了一种基于等效结构应力预测 PSJ 疲劳寿命的统一方法，包括管道和球体表面的焊趾。本文提出了一种分解和重组拟合（DRF）方法，以确定应力集中因子（SCF）的最佳函数形式。对 61 个常见 PSJ 的计算结果进行了非线性回归分析，得到了焊趾结构应力的半解析表达式。利用这种统一方法，估算了管道和球体表面焊趾的疲劳寿命。结果表明，管道表面焊趾的疲劳寿命预测值与实验结果的对数比通常为 0.93-1.08，球体表面焊趾的疲劳寿命预测值与实验结果的对数比通常为 0.97-1.13，证实了该方法的准确性。这种统一的方法适用于预测各种尺寸 PSJ 的疲劳寿命，且数学计算简洁，不需要进行有限元分析，从而方便了工程应用。DRF 方法可作为特定结构拟合 SCF 的参考。此外，这种预测方法还能确定 PSJ 的失效模式。随着钢管尺寸的增大，疲劳破坏逐渐从钢管表面转移到球体表面。

Multi-segmented fifth-order polynomial–shaped shells under hydrostatic pressure

Weeraphan Jiammeepreecha, Komkorn Chaidachatorn, Karun Klaycham, Chainarong Athisakul, Somchai Chucheepsakul

doi:10.1016/j.tws.2024.112214

静水压力下的多段五阶多项式形壳

The design and construction of submerged complex shells for new applications in offshore structures are increasingly popular. Therefore, the purpose of this study is to present the analytical model and Lagrange multipliers associated with the constraint equation for large displacement analysis of a fifth-order polynomial–shaped shell under hydrostatic pressure for the first time. The shell geometry can be computed using differential geometry with a fifth-order polynomial. The energy functional of the fifth-order polynomial–shaped shell is derived based on the principle of virtual work and written in the appropriate form. The nonlinear static responses of the fifth-order polynomial–shaped shell under hydrostatic pressure can be calculated using the nonlinear finite element method via the fifth-order polynomial shape function. This study develops the model using one-dimensional beam elements divided along the shell radius. To avoid the slope of a meridian curve at the equatorial plane approaching infinity, the shell is divided into two regions defined by different surface parameters. At the junction of two adjacent regions, the continuity requirements are established as the constraint conditions using Lagrange multipliers. The numerical results from the proposed methods are demonstrated and discussed, along with the effects of varied seawater depth, thickness, and elastic modulus on the deformed configuration and principal curvature at the deformed state. The results show that the nonlinear displacement is higher than the linear one in the case of the hydrostatic pressure, whereas the case of the internal pressure has an opposite result. For principal curvatures at the apex, the principal curvatures increase as the seawater depth increases, whereas the principal curvatures decrease when the thickness and elastic modulus increase.

水下复杂壳体的设计和建造在近海结构中的新应用日益普及。因此，本研究的目的是首次提出静水压力下五阶多项式形壳大位移分析的分析模型和与约束方程相关的拉格朗日乘数。壳的几何形状可以用五阶多项式的微分几何计算。根据虚功原理推导出了五阶多项式形壳的能量函数，并以适当的形式写出。通过五阶多项式形状函数，可以使用非线性有限元法计算五阶多项式形壳在静水压力下的非线性静态响应。本研究使用沿壳体半径划分的一维梁元素建立模型。为避免赤道面的子午线曲线斜率接近无穷大，壳体被划分为两个由不同表面参数定义的区域。在两个相邻区域的交界处，使用拉格朗日乘法器建立连续性要求作为约束条件。演示和讨论了所提方法的数值结果，以及不同海水深度、厚度和弹性模量对变形构造和变形状态下主曲率的影响。结果表明，在静水压力情况下，非线性位移高于线性位移，而在内部压力情况下，非线性位移则与线性位移相反。就顶点的主曲率而言，主曲率随海水深度的增加而增大，而当厚度和弹性模量增加时，主曲率则减小。