【新文速递】2023年12月18日固体力学SCI期刊最新文章

今日更新：International Journal of Solids and Structures 2 篇，Journal of the Mechanics and Physics of Solids 1 篇，Mechanics of Materials 1 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 7 篇

International Journal of Solids and Structures

On the problem of a Gurtin–Murdoch cylindrical material surface embedded in an infinite matrix

Zhilin Han, Sofia G. Mogilevskaya, Anna Y. Zemlyanova

doi:10.1016/j.ijsolstr.2023.112617

关于嵌入无限矩阵中的Gurtin-Murdoch圆柱形材料表面问题

The problem of an infinite isotropic elastic matrix subjected to uniform far-field load and containing a Gurtin–Murdoch material surface of cylindrical shape is considered in plane strain setting. The governing equations and the boundary conditions for the problem, reduced to that of an infinite plane containing a material curve along a circular arc, are reviewed. The displacements inside the matrix are sought in the complex variables form of a single layer elastic potential whose density represents the jump in complex tractions across the curve. Exact complex integral representations for the elastic fields everywhere in the material are provided and the problem is further reduced to the system of real variables hypersingular boundary integral equations in terms of the strain and rotation components associated with the curve. The components are then approximated by the series of trigonometric functions that are multiplied by the square root weight functions to allow for automatic incorporation of the tip conditions. The unknown coefficients in the series are found from the system of linear algebraic equations that is solved using standard collocation method. The numerical examples are presented to illustrate the influence of dimensionless parameters with the main focus on the study of curvature-induced effects.

考虑了在均匀远场载荷作用下含有圆柱形Gurtin-Murdoch材料表面的无限各向同性弹性矩阵的平面应变设置问题。讨论了该问题的控制方程和边界条件，并将其简化为包含沿圆弧的材料曲线的无限平面问题。矩阵内部的位移以复变量形式的单层弹性势来求，其密度表示复杂牵引力在曲线上的跳跃。给出了材料中各处弹性场的精确复积分表示，并进一步将问题简化为与曲线相关的应变分量和旋转分量的实变量超奇异边界积分方程组。然后通过一系列三角函数乘以平方根权重函数来近似这些分量，以允许自动合并尖端条件。该级数中的未知系数由线性代数方程组求出，用标准配置法求解。通过数值算例说明了无量纲参数的影响，重点研究了曲率效应。

Rate-independent gradient-enhanced crystal plasticity theory — Robust algorithmic formulations based on incremental energy minimization

Volker Fohrmeister, Jörn Mosler

doi:10.1016/j.ijsolstr.2023.112622

速率无关的梯度增强晶体塑性理论-基于增量能量最小化的鲁棒算法公式

Numerically robust algorithmic formulations suitable for rate-independent crystal plasticity are presented. They cover classic local models as well as gradient-enhanced theories in which the gradients of the plastic slips are incorporated by means of the micromorphic approach. The elaborated algorithmic formulations rely on the underlying variational structure of (associative) crystal plasticity. To be more precise and in line with so-called variational constitutive updates or incremental energy minimization principles, an incrementally defined energy derived from the underlying time-continuous constitutive model represents the starting point of the novel numerically robust algorithmic formulations. This incrementally defined potential allows to compute all variables jointly as minimizers of this energy. While such discrete variational constitutive updates are not new in general, they are considered here in order to employ powerful techniques from non-linear constrained optimization theory in order to compute robustly the aforementioned minimizers. The analyzed prototype models are based on (1) nonlinear complementarity problem (NCP) functions as well as on (2) the augmented Lagrangian formulation. Numerical experiments show the numerical robustness of the resulting algorithmic formulations. Furthermore, it is shown that the novel algorithmic ideas can also be integrated into classic, non-variational, return-mapping schemes.

提出了适用于速率无关晶体塑性的数值鲁棒算法公式。它们包括经典的局部模型以及梯度增强理论，其中塑性滑移的梯度通过微形态方法被纳入。详细阐述的算法公式依赖于(联想)晶体塑性的潜在变分结构。为了更精确地符合所谓的变分本构更新或增量能量最小化原则，从潜在的时间连续本构模型中获得的增量定义能量代表了新的数值鲁棒算法公式的起点。这种增量定义的势能允许将所有变量联合计算为能量的最小值。虽然这种离散变分本构更新通常并不新鲜，但这里考虑它们是为了利用非线性约束优化理论的强大技术来鲁棒地计算上述最小值。所分析的原型模型基于(1)非线性互补问题(NCP)函数和(2)增广拉格朗日公式。数值实验证明了所得到的算法公式的数值鲁棒性。此外，还证明了这种新的算法思想也可以集成到经典的、非变分的、返回映射的方案中。

Journal of the Mechanics and Physics of Solids

Exceptional stress-director coupling at the crack tip of a liquid crystal elastomer

Chen Wei, Yu Zhou, Benny Hsu, Lihua Jin

doi:10.1016/j.jmps.2023.105522

液晶弹性体裂纹尖端的特殊应力导向耦合

A liquid crystal elastomer (LCE) is a special elastomer containing rod-like liquid crystals, which align in a certain direction, called the director. The director of a LCE can rotate under stress, resulting in large spontaneous strain and soft elastic behavior. This study unravels how the strong stress-director coupling in a monodomain LCE induces unique crack-tip fields and fracture behavior. Through stretching edge-cracked LCEs with various initial directors, we characterize the displacement and director fields theoretically and experimentally. The results reveal that the directors undergo significant and inhomogeneous rotation at the crack tips, leading to very different stress/strain distributions from traditional elastomers. Particularly, when the initial director is tilted to the loading direction, the stress/strain distributions are asymmetrical about the crack plane. Notably, we discover a domain wall forms along a certain polar angle at the crack tip, with opposite director rotation, and thereby shear strain, on the two sides of the domain wall. Moreover, LCEs with a tilted initial director to the loading exhibit much smaller crack openings and energy release rates than those of neo-Hookean materials, while LCEs with a parallel director exhibit higher values. We attribute these findings to a combined effect of bulk softening at the remote region and the formation of domains of opposite director rotation near the crack tip. This study provides an understanding of how the stress-director coupling of LCEs triggers their unique crack-tip fields, and insights into strategies to enhance the fracture properties of LCEs for future applications.

液晶弹性体(LCE)是一种含有棒状液晶的特殊弹性体，这些液晶按一定的方向排列，称为指向性。LCE的导向器在应力作用下可以旋转，产生较大的自发应变和软弹性行为。本研究揭示了单畴LCE中强应力指向耦合如何诱导独特的裂纹尖端场和断裂行为。通过拉伸具有不同初始导向的边缘裂纹LCEs，从理论上和实验上对位移场和导向场进行了表征。结果表明，在裂纹尖端，定向器发生了明显的不均匀旋转，导致应力/应变分布与传统弹性体非常不同。特别是当初始方向向加载方向倾斜时，裂纹面上的应力应变分布是不对称的。值得注意的是，我们发现在裂纹尖端沿一定的极角形成了一个畴壁，方向旋转相反，因此在畴壁的两侧形成了剪切应变。此外，与新hookean材料相比，初始导向向载荷倾斜的LCEs表现出更小的裂纹开口和能量释放率，而平行导向的LCEs则表现出更高的数值。我们将这些发现归因于在偏远地区的大块软化和在裂纹尖端附近形成的相反方向旋转域的综合影响。该研究为lce的应力导向耦合如何触发其独特的裂纹尖端场提供了理解，并为未来应用提供了提高lce断裂性能的策略。

Mechanics of Materials

Micromechanical modeling of the effects of crystal content on the visco-hyperelastic-viscoplastic behavior and fracture of semi-crystalline polymers

G. Ayoub, M. Makki, R. Kadri, R. Dargazany, M. Nait Abdelaziz

doi:10.1016/j.mechmat.2023.104897

晶体含量对半结晶聚合物粘-超弹-粘塑性行为和断裂影响的微观力学模拟

In this work, we present a novel physically based visco-hyperelastic-viscoplastic micromechanical constitutive model, which establishes a link between the evolution of the macromolecular network properties to the mechanical and fracture behavior of variable-crystallinity semi-crystalline polymers. Unlike previous micromechanical constitutive models that were only time independent, we propose a time-dependent scheme. It employs the computational effective eight-chain model for micro-macro transition while assuming a composite structure for the polymer. Thus, an innovative approach that couples the deformation and damage of individual polymer chains is developed. The proposed constitutive framework assumes that the stress developed through the deformation of semi-crystalline polymers is the sum of a macromolecular network and an intermolecular part. The macromolecular part accounts for the conformational change associated with Kuhn segments reorientation and the bond potential associated with the deformation of the bonds between Kuhn segments. Meanwhile, the intermolecular part accounts for the deformation of the crystalline and the amorphous phases. The constitutive equations are integrated using a mixed explicit/implicit integration algorithm. To validate and calibrate our model, we utilize uniaxial tensile experimental data obtained from three different polyethylene materials with varying crystallinity levels and different strain rates. We propose a robust calibration procedure, ensuring the identification of a single set of parameters that remain independent of crystal content and strain rate. Finally, we assess the model's predictive capabilities in predicting the mechanical behavior and fracture at different strain rates for variable-crystallinity polyethylene is evaluated. This comprehensive approach enhances our understanding and predictive capacity in modeling the intricate mechanical response up to fracture of semi-crystalline polymers under diverse conditions.

在这项工作中，我们提出了一种新的基于物理的粘-超弹-粘塑性微力学本构模型，该模型建立了大分子网络特性的演变与变结晶度半晶聚合物的力学和断裂行为之间的联系。不像以前的微观力学本构模型，只有时间无关，我们提出了一个时间相关的方案。它采用计算有效的八链模型进行微观宏观过渡，同时假设聚合物为复合结构。因此，开发了一种耦合单个聚合物链的变形和损伤的创新方法。提出的本构框架假设通过半结晶聚合物的变形产生的应力是大分子网络和分子间部分的总和。大分子部分解释了与库恩段重定向相关的构象变化和与库恩段之间键的变形相关的键势。同时，分子间部分导致了结晶和非晶相的变形。采用显式/隐式混合积分算法对本构方程进行积分。为了验证和校准我们的模型，我们使用了从三种不同的聚乙烯材料中获得的单轴拉伸实验数据，这些材料具有不同的结晶度和不同的应变率。我们提出了一个稳健的校准程序，确保识别一组独立于晶体含量和应变率的参数。最后，我们评估了该模型在预测变结晶度聚乙烯在不同应变速率下的力学行为和断裂方面的预测能力。这种综合的方法提高了我们对半结晶聚合物在不同条件下断裂的复杂力学响应建模的理解和预测能力。

International Journal of Plasticity

Effect of grain boundary misorientation and carbide precipitation on damage initiation: A coupled crystal plasticity and phase field damage study

Michael Salvini, Nicolò Grilli, Eralp Demir, Siqi He, Tomas Martin, Peter Flewitt, Mahmoud Mostafavi, Christopher Truman, David Knowles

doi:10.1016/j.ijplas.2023.103854

晶界取向错误和碳化物析出对损伤起始的影响:晶体塑性和相场损伤的耦合研究

A coupled crystal plasticity phase field damage framework has been developed and applied to modelling damage initiation. A novel implementation of a grain misorientation angle dependent critical energy release rate has been used to determine a reduction in the local critical energy release rate resulting from the effects of intergranular carbide precipitates and grain boundary misorientation. When applied to a notched high temperature 316H austenitic stainless steel specimen, a good correlation between experimental results and void nucleation statistics for a misorientation dependent critical energy release rate was obtained. This has been evaluated through comparison with correlative electron microscopy experimental results, showing the potential of phase field models in the area of early damage formation. Additions to include plastic strain and creep deformation effects were made, and comparisons were drawn with experimental data to investigate the contributions of microstructural geometry properties such as the difference in and average values of Schmid factors across grain boundaries, as well as the loading direction stress and dislocation densities. The limitations to this approach and opportunities for further work in this area are discussed, with specific interest in the need for additional literature data characterising grain boundary carbide precipitation and cavity nucleation analysis.

建立了一种晶体塑性相场耦合损伤框架，并将其应用于损伤起爆模拟。一种依赖于晶粒错取向角的临界能量释放率的新方法被用来确定由于晶间碳化物析出和晶界错取向的影响而导致的局部临界能量释放率的降低。当对316H高温缺口奥氏体不锈钢试样进行实验时，实验结果与错误取向依赖的临界能量释放率的空洞成核统计数据之间有很好的相关性。通过与相关的电镜实验结果进行比较，表明了相场模型在早期损伤形成区域的潜力。加入了塑性应变和蠕变效应，并与实验数据进行了比较，探讨了施密德因子跨晶界差和平均值、加载方向应力和位错密度等微观组织几何特性的影响。讨论了这种方法的局限性和在该领域进一步工作的机会，特别感兴趣的是需要额外的文献数据来表征晶界碳化物析出和空腔成核分析。

Thin-Walled Structures

Analytical study on the dynamic mechanical behaviours of foam-core sandwich plate under repeated impacts

Wen Xiao, Yinggang Li, Yong Hu, Zeyuan Song, Wei Cai, Xiaobin Li

doi:10.1016/j.tws.2023.111480

反复冲击作用下泡沫芯夹芯板动态力学性能分析研究

The foam-core sandwich structures are probably subjected to repeated impact loadings in engineering applications, resulting in structural plastic deformation and accumulative damage. A valuable analytical approach is needed to predict the accumulative plastic deformation of foam-core sandwich structures under repeated impacts. In this paper, an analytical model of the dynamic responses of foam-core sandwich plates under repeated impacts is proposed using the circumscribing yield locus and the inscribing yield locus based on the rigid-perfectly plastic theory. By employing the principle of energy dissipation rate balance, the analytical expressions of structure permanent deformation and peak force are obtained from the iteration of initial conditions. In addition, polyvinyl chloride (PVC) foam has steady chemical properties and corrosion resistance, which can better adapt to the practical environment and meet the needs of structural protection. To validate the proposed analytical model, the repeated impact dynamic mechanical behaviours of PVC foam-core sandwich plates were experimentally and numerically studied. Results show that theoretical results such as the permanent deformation, peak force, and deformation modes of foam-core sandwich plates under repeated impacts are in good agreement with experimental and numerical results. With the increase in impact numbers, the global bending deformation and local indentation deformation of facesheets increase, the PVC foam core layer is constantly being compressed, and the bottom facesheet plays an increasingly important part in the repeated impact energy absorption with a maximum value of 29.20%.

在工程应用中，泡沫芯夹层结构可能会受到反复的冲击载荷，导致结构塑性变形和累积损伤。需要一种有价值的分析方法来预测泡沫芯夹层结构在反复冲击下的累积塑性变形。本文基于刚-完全塑性理论，采用边界屈服轨迹和内嵌屈服轨迹，建立了泡沫芯夹层板在重复冲击作用下的动力响应解析模型。利用能量耗散率平衡原理，对初始条件进行迭代，得到结构永久变形和峰值力的解析表达式。此外，聚氯乙烯(PVC)泡沫具有稳定的化学性能和耐腐蚀性，可以更好地适应实际环境，满足结构保护的需要。为了验证所提出的分析模型，对PVC泡沫芯夹层板的重复冲击动态力学行为进行了实验和数值研究。结果表明:泡沫芯夹层板在重复冲击作用下的永久变形、峰值力和变形模式等理论结果与实验和数值结果吻合较好;随着冲击次数的增加，面板整体弯曲变形和局部压痕变形增加，PVC泡沫芯层不断被压缩，底部面板在重复冲击吸能中发挥越来越重要的作用，其最大值为29.20%。

A Numerically Stable Flexural Dynamics Model of Complex Multi-span Fluid-conveying Pipes with Flexible Components and its Application to Clamp Stiffness Identification

Ze-Chao Wang, Pei-Xin Gao, Zu-De Zhou, Arris-S Tijsseling, Yong-Zhi Qu, Wang-Ji Yan, Ka-Veng Yuen, Shing Shin Cheng

doi:10.1016/j.tws.2023.111488

含柔性构件的复杂多跨流体输送管道数值稳定弯曲动力学模型及其在卡箍刚度识别中的应用

Multi-span fluid-conveying pipelines (MFP) with multiple concentrated accessories, i.e., clamps, valves, flanges, vibration absorbers and flexible components, whose dynamic properties can be described by receptance, are widely used in many engineering fields. However, research on predicting the dynamics of such pipe structures has been rarely performed. In this study, we propose an improved transfer matrix method (TMM) to model the numerically stable dynamics of the MFP with multiple concentrated accessories and flexible components. An original receptance-based modelling method is developed to address boundary conditions induced by the presence of concentrated accessories and flexible components simultaneously. The method's advantage is that the flexible component is considered as an independent substructure before assembling, its receptance can be calculated or measured independently. Moreover, the numerical instability problem of the conventional transfer matrix method (CTMM) in the high-frequency range is resolved by utilizing a successive reduction process to reduce the length of the transfer path of the state vectors used to describe the overall dynamics of the pipe. One salient feature of the proposed method is that the size of the characteristic matrix will be specified as 4×4, which is inherited from CTMM. An optimization-based inverse method is proposed to identify the clamp stiffness with the developed numerically stable and efficient dynamics model. Also, a device is designed and developed to measure the approximate clamp stiffness values which are considered as the initial values during optimization. The experimental results indicate that the proposed method is effective and accurate; utilizing the approximate values of the clamp stiffness as the initial values can accelerate the stability of the iteration during the optimization.

多跨流体输送管道(MFP)具有多个集中的附件，即夹具、阀门、法兰、减振器和柔性部件，其动态性能可以用接收来描述，广泛应用于许多工程领域。然而，对这种管道结构进行动力学预测的研究却很少。在这项研究中，我们提出了一种改进的传递矩阵法(TMM)来模拟具有多个集中附件和柔性部件的MFP的数值稳定动力学。提出了一种新颖的基于接受度的建模方法，以解决由集中附件和柔性部件同时存在所引起的边界条件。该方法的优点是在装配前将柔性元件视为一个独立的子结构，可以独立地计算或测量其接受度。此外，利用连续约简过程减小用于描述管道整体动力学的状态向量的传递路径长度，解决了传统传递矩阵法(CTMM)在高频范围内的数值不稳定性问题。该方法的一个显著特点是特征矩阵的大小将被指定为4×4，它继承自CTMM。利用所建立的数值稳定、高效的动力学模型，提出了一种基于优化的钳位刚度反演方法。此外，设计并开发了一种装置来测量钳位刚度的近似值，该值作为优化过程中的初始值。实验结果表明，该方法有效、准确;在优化过程中，利用钳位刚度的近似值作为初始值可以加快迭代的稳定性。

Closed-form approach for the elastic critical moment of I-girders with corrugated web

David Fernandez-Lacabe, Claudio López, Miguel-Angel Serna

doi:10.1016/j.tws.2023.111492

波纹腹板工字梁弹性临界弯矩的闭式求解

Using corrugated web girders offers several advantages, including increased resistance to lateral-torsional buckling. Researchers have proposed various methods for determining the critical moment value as a function of the cross-sectional geometry. Previous studies have suggested that the enhanced critical moment is attributable to a larger warping constant. In this paper, we present the results of a systematic numerical study using finite element analysis on girders with various corrugated web shapes. Bending along the weak axis demonstrates that corrugated web girders possess a higher moment of inertia. Furthermore, our torsion linear analysis indicates that the increase in the critical moment is primarily due to a larger torsional constant. We compare the elastic critical moment values obtained using finite element linear buckling analysis to those derived from theoretical expressions that introduce equivalent section properties. Our results illustrate that the equivalent section properties method provides values that closely resemble those obtained using finite elements. Finally, we provide closed-form expressions that can be used to estimate equivalent section properties for any girder with a corrugated web. Our findings suggest that employing these expressions to calculate the critical moment yields results that are satisfactory when compared to those obtained through finite element linear buckling analysis.

使用波纹腹板梁有几个优点，包括增加抗侧向扭转屈曲。研究人员提出了各种方法来确定临界矩值作为截面几何的函数。先前的研究表明，临界矩的增强是由于较大的翘曲常数。在本文中，我们提出了一个系统的数值研究的结果，采用有限元分析的不同波形腹板形状的梁。沿弱轴弯曲表明波纹腹板梁具有较高的转动惯量。此外，我们的扭转线性分析表明，关键时刻的增加主要是由于更大的扭转常数。我们比较了用有限元线性屈曲分析得到的弹性临界弯矩值和引入等效截面特性的理论表达式得到的弹性临界弯矩值。我们的结果表明，等效截面特性方法提供的值与使用有限元得到的值非常相似。最后，我们提供了封闭形式的表达式，可用于估计任何波形腹板梁的等效截面特性。我们的研究结果表明，与有限元线性屈曲分析结果相比，采用这些表达式计算临界力矩的结果令人满意。