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【新文速递】2024年9月12日固体力学SCI期刊最新文章

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今日更新:International Journal of Solids and Structures 2 篇,Journal of the Mechanics and Physics of Solids 4 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 3 篇

International Journal of Solids and Structures

Mixed variational formulation and finite-element implementation of second-order poro-elasticity

Hamza Khurshid, Elten Polukhov, Marc-André Keip

doi:10.1016/j.ijsolstr.2024.113055

二阶孔隙弹性的混合变分公式及有限元实现

We present a variational formulation of second-order poro-elasticity that can be readily implemented into finite-element codes by using standard Lagrangian interpolation functions. Point of departure is a two-field minimization principle in terms of the displacement and the fluid flux as independent variables. That principle is taken as a basis for the derivation of continuous and incremental saddle-point formulations in terms of an extended set of independent variables. By static condensation this formulation is then reduced to a minimization principle in terms of the displacement and fluid flux as well as associated higher-order fields. Once implemented into a finite-element code, the resulting formulation can be applied to the numerical simulation of porous media in consideration of second-order effects. Here, we analyze the model response by means of several example problems including two standard tests in poro-elasticity, namely the consolidation problems of Terzaghi and Mandel, and compare the results with those of a corresponding first-order model. As becomes clear, the second-order formulation can unleash its full potential when applied to the study of porous media having spatial dimensions comparable to the size of their microstructure. In particular, it is capable to regularize steep field gradients at external as well as internal surfaces and to describe material dilatation effects known from experiments.

我们提出了一个二阶孔隙弹性的变分公式,它可以很容易地通过使用标准拉格朗日插值函数实现到有限元代码中。出发点是以位移和流体通量为自变量的双场最小化原理。这一原理被用来作为根据一组扩展的自变量推导连续和增量鞍点公式的基础。通过静态冷凝,该公式就位移和流体通量以及相关的高阶场而言被简化为最小化原则。一旦实现成有限元程序,所得公式可以应用于考虑二阶效应的多孔介质的数值模拟。在这里,我们通过几个例子问题来分析模型的响应,包括两个标准的孔隙弹性试验,即Terzaghi和Mandel固结问题,并将结果与相应的一阶模型的结果进行比较。随着越来越清楚,二阶公式可以释放其全部潜力,当应用于多孔介质的研究具有相当的空间尺寸,其微观结构的大小。特别是,它能够正则化外部和内部表面的陡场梯度,并描述从实验中已知的物质膨胀效应。


Generalized prismatic tensegrity derived by dihedral symmetric lines

Liheng Wu, Jianguo Cai

doi:10.1016/j.ijsolstr.2024.113068

由二面体对称线导出的广义棱柱张拉整体

Classic prismatic tensegrity structures, characterized by dihedral symmetry with one orbit of nodes, are among the simplest and possibly the earliest spatial tensegrity structures invented. This paper introduces a generalized form of the prismatic tensegrity structures by converting a single-loop linkage into truss, and the joint axes of the linkages form a set of linear dependent lines with dihedral symmetry of one orbit. Consequently, the dihedral symmetry of resulting tensegrity structures is characterized by lines passing the nodes in pairs rather than the nodes themselves. The generated tensegrity structures are kinematically and statically indeterminate, generally, and are called dihedral-line tensegrity structures in this paper. A necessary condition for prestress stability of the generated tensegrity is presented using higher-order analysis of screws. Specifically, this paper focuses on symmetric dihedral-line tensegrity structures, in which the nodes also have dihedral symmetry in two orbits and members in seven orbits. It is found that there are at least N struts for the generated tensegrity with DN symmetry. Several examples illustrate how the classic prismatic tensegrity structures are recovered from these dihedral-line tensegrity structures by removing certain zero-force members. Symmetric-adapted force density matrices are also provided as well as the relation to that of the classic prismatic tensegrity. Given 4N+6 dimensional parameters inherent to these tensegrity structures, a rich variety of tensegrity structure family is presented.

经典的棱柱式张拉整体结构具有二面对称的特点,节点为一轨道,是最简单也可能是最早发明的空间张拉整体结构之一。本文介绍了棱柱式张拉整体结构的广义形式,将单环连杆转换为桁架,连杆的连接轴形成一组线性隶属线,具有一轨道的二面对称性。因此,生成的张拉整体结构的二面对称性特征是成对通过节点的线,而不是节点本身。一般来说,生成的张拉实体结构在运动学和静力学上都是不确定的,本文将其称为二面体线张拉实体结构。本文利用螺钉的高阶分析提出了生成的张拉整体预应力稳定性的必要条件。具体而言,本文重点研究对称二面体线张拉整体结构,其中节点在两个轨道上也具有二面体对称性,而构件在七个轨道上也具有二面体对称性。研究发现,生成的具有 DN 对称性的张拉整体至少有 N 个支柱。几个例子说明了如何通过移除某些零力构件,从这些二面线张拉结构中恢复出经典的棱柱张拉结构。此外,还提供了经对称调整的力密度矩阵以及与经典棱柱型张拉整体结构的关系。考虑到这些张弦结构固有的 4N+6 维参数,呈现了丰富多样的张弦结构族。


Journal of the Mechanics and Physics of Solids

Adhesive and Cohesive Fracture of Blood Clots: Experiments and Modeling

Shiyu Liu, Aram Bhamani, Gabriella Paige Sugerman, Zhen Yang, Manuel Rausch, Farshid Ghezelbash, Jianyu Li

doi:10.1016/j.jmps.2024.105858

血凝块的黏附性和内聚性骨折:实验和模型

Blood clots represent living materials composed of a polymer network and an abundance of cells. They might fracture within the bulk material of the clot (cohesive fracture), at the interface between the clot and surrounding tissue (adhesive fracture), or through a combination of both modes (hybrid fracture). The clot fracture within vascular systems and injury sites could lead to life-threatening conditions. Despite the significance, understanding and modeling the fracture behaviors of blood clots, including their dependence on mechanical loading and cellular components, remain in a nascent stage. In this study, we employ an integrated experimental-computational approach to comprehensively investigate the fracture behaviors of bovine blood clots. We explore various mechanical factors, substrates, and cellular components such as red blood cells (RBCs) and platelets. Our findings reveal that among various tissue substrates, blood clots exhibit the highest interfacial adhesion energy with muscle, and the lowest to the inner arterial lining, consistent with their biological function. Both interfacial and bulk fracture energies are rate-dependent, although they exhibit different dependencies. Also, RBCs and platelets have different effects on clot fracture. An increase in RBC content tends to toughen both adhesion and fracture of blood clots. However, an increase in platelet content enhances interfacial adhesion energy but lowers the bulk fracture energy. The platelet content also governs the shift from adhesive fracture to hybrid fracture. To model clot fracture, we developed two finite element models incorporating a coupled cohesive-zone and Mullins-effect approach to simulate pure shear fracture and peeling of blood clots. These models, validated through experimental data, elucidate the interplay between intrinsic fracture toughness, interfacial strength, and bulk energy dissipation during clot fracture. This study significantly advances our understanding of clot mechanics, providing valuable insights into the mechanics of similar living materials and the management of clot-related disorders such as hemorrhage and thrombosis.

血凝块是由聚合物网络和大量细胞组成的活物质。它们可能在血块的大块材料内断裂(内聚性断裂),也可能在血块与周围组织的界面处断裂(粘连性断裂),或者通过两种模式的结合(混合型断裂)。血管系统和损伤部位的血栓破裂可能导致危及生命的情况。尽管具有重要意义,但对血凝块断裂行为的理解和建模,包括它们对机械载荷和细胞成分的依赖,仍处于初级阶段。在这项研究中,我们采用了一种综合的实验计算方法来全面研究牛血凝块的断裂行为。我们探讨了各种机械因素,底物和细胞成分,如红细胞(rbc)和血小板。我们的研究结果表明,在各种组织基质中,血凝块与肌肉的界面粘附能最高,与动脉内壁的界面粘附能最低,这与它们的生物学功能一致。界面和整体断裂能都是速率相关的,尽管它们表现出不同的依赖关系。此外,红细胞和血小板对凝块骨折的影响也不同。红细胞含量的增加会使血栓的粘连和破裂变得更韧。然而,血小板含量的增加增加了界面粘附能,但降低了整体断裂能。血小板含量也决定了粘连骨折向混合型骨折的转变。为了模拟血块断裂,我们开发了两个有限元模型,结合了耦合黏结区和mullins效应方法来模拟纯剪切断裂和血块剥离。这些模型通过实验数据验证,阐明了凝块断裂过程中固有断裂韧性、界面强度和块能量耗散之间的相互作用。这项研究显著地推进了我们对凝块机制的理解,为类似生物材料的机制和凝块相关疾病(如出血和血栓形成)的管理提供了有价值的见解。


Fracture and size effect in mechanical metamaterials

J. Ulloa, M.P. Ariza, J.E. Andrade, M. Ortiz

doi:10.1016/j.jmps.2024.105860

机械超材料的断裂与尺寸效应

We resort to variational methods to evaluate the asymptotic behavior of fine metamaterials as a function of cell size. To zeroth order, the metamaterial behaves as a micropolar continuum with both displacement and rotation degrees of freedom, but exhibits linear-elastic fracture mechanics scaling and therefore no size effect. To higher order, the overall energetics of the metastructure can be characterized explicitly in terms of the solution of the zeroth-order continuum problem by the method of Γ-expansion. We present explicit expressions of the second-order correction for octet frames. As an application, we evaluate the compliance of double-cantilever octet specimens to second order and use the result to elucidate the dependence of the apparent toughness of the specimen on cell size. The analysis predicts the discreteness of the metamaterial lattice to effectively shield the crack-tip, a mechanism that we term lattice shielding. The theory specifically predicts anti-shielding, i. e., coarser is weaker, in agreement with recent experimental observations.

我们采用变分法来评估精细超材料的渐近行为与细胞尺寸的函数关系。在零阶,超材料表现为具有位移和旋转自由度的微极性连续体,但表现出线性弹性断裂力学缩放,因此没有尺寸效应。在更高阶的情况下,超材料结构的整体能量学可以通过Γ-展开方法对零阶连续性问题的求解进行明确表征。我们提出了八面体框架二阶修正的明确表达式。作为应用,我们评估了双悬臂八面体试样的二阶顺应性,并利用该结果阐明了试样表观韧性与单元尺寸的关系。分析预测超材料晶格的离散性可有效屏蔽裂纹尖端,我们称之为晶格屏蔽机制。该理论特别预测了反 屏蔽,即越粗则越弱,这与最近的实验观察结果一致。


Stress–strain hysteresis during hydrostatic loading of porous rocks

Alvin T. Biyoghé, Yves M. Leroy, Lucas Pimienta, Robert W. Zimmerman

doi:10.1016/j.jmps.2024.105861

多孔岩石静水加载过程中的应力-应变滞后现象

A micro-mechanical model is proposed to predict the stress–strain hysteresis during the cyclic hydrostatic loading of fluid-saturated rocks under drained or undrained conditions. A spherical pore is surrounded by a multi-cracked shell where local deviatoric stress develops despite the remote hydrostatic loading. The effective properties of the material composing the shell are constructed assuming an isotropic distribution of cracks with no interaction, and the overall properties thanks to the spherical assemblage approach. The fluid pressure in drained and undrained conditions is assumed to be uniform throughout the assemblage. A new analytical solution is proposed, assuming all cracks are closed and slipping either forwardly or reversely. It is shown with numerical simulations for drained conditions that this assumption is indeed respected for sufficiently small values of the crack friction angle. However, for reasonable values, the closed cracks during the unloading phase could slip in either direction: reversely close to the pore and still forwardly away from the pore. Moreover, at critical radii, the slip could occur in either direction depending on the crack orientation. A similar micro-structural response is observed for undrained conditions, although the remote confining stress required to close the cracks is much larger. The model’s predictions compare favourably with recent experimental data on dry sandstones and carbonates, which were presented in a study on the influence of strain amplitude on the transition between static and dynamic properties. The crack density and matrix elasticity modulus are sufficient fitting parameters to accurately predict the hysteresis loops, especially for porosity levels above 10%.

提出了一种细观力学模型来预测排水和不排水条件下饱和流体岩石在循环静水加载过程中的应力-应变滞后现象。一个球形孔是由一个多裂纹壳包围,局部偏应力发展,尽管远静水加载。构成壳体的材料的有效性能是在假设裂纹的各向同性分布而没有相互作用的情况下构建的,而整体性能则是通过球面组合方法构建的。假定在排水和不排水条件下的流体压力在整个组合中是均匀的。提出了一种新的解析解,假设所有裂缝都是闭合的,并且正向或反向滑动。排水条件下的数值模拟表明,当裂纹摩擦角值足够小时,这一假设确实得到了尊重。然而,在合理的数值范围内,卸载阶段闭合的裂缝可以向两个方向滑动:反向靠近孔隙,仍然向前远离孔隙。此外,在临界半径处,滑移可能发生在任何方向,这取决于裂纹的方向。在不排水条件下也观察到类似的微观结构响应,尽管闭合裂缝所需的远端围应力要大得多。该模型的预测与最近关于干砂岩和碳酸盐岩的实验数据相比较有利,这些数据是在一项关于应变幅值对静态和动态性质之间转换的影响的研究中提出的。裂纹密度和基体弹性模量是能够准确预测迟滞回线的拟合参数,特别是在孔隙率大于10%的情况下。


Free Energy and Extension of Stiff Polymer Chains Confined in Nanotubes with Diverse Cross-Sectional Shapes

Yihan Zhao, Jizeng Wang

doi:10.1016/j.jmps.2024.105862

不同截面形状纳米管中刚性聚合物链的自由能和延伸

The statistical mechanics of stiff polymer chains confined within narrow tubes is a foundational topic in polymer physics, extensively analyzed in prior research. For cylindrical, rectangular, and slit-like confinements, the chains’ free energy and extension adhere to a scaling law consistent with the Odijk theory. While this scaling law may not apply to tubes with different cross-sectional geometries, there is a lack of research examining the behavior of stiff chains in tubes with intricate cross-sectional shapes. In this study, we investigate the partition function of a stiff chain confined within an elliptic tube using the path integral approach, deriving a deflection length in a concise closed form through dimensional analysis. This length scale facilitates straightforward expressions for the chain's free energy and extension. Notably, we discover a shape-independent property of these expressions applicable to tubes with a wide variety of cross-sectional geometries. Extensive numerical simulations are conducted using a biased chain-growth Monte Carlo method, incorporating the Pruned and Enriched Rosenbluth algorithm, to validate the theoretical predictions on the confinement free energy and extension of chains in tubes with differing shapes.

窄管内刚性聚合物链的统计力学是聚合物物理学的一个基础问题,在以往的研究中得到了广泛的分析。对于圆柱形、矩形和裂隙状约束,链的自由能和延伸遵循与Odijk理论一致的标度定律。虽然该标度定律可能不适用于具有不同横截面几何形状的管,但缺乏对具有复杂横截面形状的管中刚性链行为的研究。在本研究中,我们使用路径积分方法研究了限制在椭圆管内的刚性链的配分函数,通过量纲分析得出了简洁封闭形式的挠度长度。这个长度标度便于直接表示链的自由能和延伸。值得注意的是,我们发现这些表达式适用于具有各种截面几何形状的管的形状无关性质。采用偏置链生长蒙特卡罗方法进行了大量的数值模拟,并结合了修剪和充实的Rosenbluth算法,以验证不同形状管中约束自由能和链延伸的理论预测。


International Journal of Plasticity

Revealing the fatigue strengthening and damage mechanisms of surface-nanolaminated gradient structure

Yong Zhang, Chen-Yun He, Xiaogang Wang, Takayuki HAMA, Binhan Sun, Yun-Fei Jia, Xian-Cheng Zhang, Shan-Tung Tu

doi:10.1016/j.ijplas.2024.104128

揭示了表面纳米层状梯度结构的疲劳强化和损伤机理

Extending the fatigue life of metals is a critical concern for maintaining material and component integrity in engineering systems. The integration of gradient structures within materials represents a highly promising approach to enhance the fatigue properties in metallic materials, while a detailed mechanistic understanding of the fatigue damage evolution of such structures is yet to be developed. Here, we report that the surface-nanolaminated gradient structure comprised of nanolaminates and hierarchical twins imparts remarkable resistance to both low-cycle and high-cycle fatigue. A dislocation-based strain gradient crystal plasticity model is developed to investigate the strengthening and damage mechanisms of our gradient structure. The size dependence of the initial dislocation density, its evolution and back stress hardening are taken into account and verified by the experimental data. The simulation results reveal that the strain delocalization and back stress hardening induced by the structure gradient significantly mitigate the fatigue damage accumulation. Additionally, in contrast to conventional gradient structures, the mechanical stability of the present structure enables these strengthening mechanisms to persist until crack initiation. These effects, combined with the sequential toughening mechanisms activated in the surface-nanolaminated gradient structure, ensure a marked life extension under low-cycle fatigue (by a factor of four), outperforming conventional gradient and other microstructural design strategies. Finally, a multiscale anti-fatigue design principal for damage homogenization is given based on the prior quantitative analysis.

延长金属的疲劳寿命是保持工程系统中材料和部件完整性的关键问题。材料内部梯度结构的集成是提高金属材料疲劳性能的一种非常有前途的方法,但对这种结构疲劳损伤演变的详细机制理解尚未得到发展。在这里,我们报道了由纳米层合物和分层孪晶组成的表面纳米层化梯度结构对低周和高周疲劳具有显著的抵抗力。建立了基于位错的应变梯度晶体塑性模型,研究了梯度结构的强化和损伤机理。考虑了初始位错密度、位错演化和背应力硬化的尺寸依赖性,并用实验数据进行了验证。模拟结果表明,结构梯度引起的应变离域和背应力硬化显著减缓了疲劳损伤的积累。此外,与传统的梯度结构相比,当前结构的机械稳定性使这些强化机制能够持续到裂纹萌生。这些效应,再加上在表面纳米层化梯度结构中激活的顺序增韧机制,确保了在低周疲劳下的显著寿命延长(四倍),优于传统的梯度和其他微结构设计策略。最后,在先前定量分析的基础上,给出了损伤均匀化的多尺度抗疲劳设计原则。


Thin-Walled Structures

Prediction of sectional collapse of thin-walled structure under pure bending by nonlinear composite beam theory

Fang Jiang, Wenbin Yu

doi:10.1016/j.tws.2024.112414

用非线性组合梁理论预测薄壁结构在纯弯曲作用下的截面倒塌

Brazier (1927) found that when one dimension of the beam cross-section was relatively smaller than the others, large in-plane displacements over the cross-section might occur, even though the strains could remain very small. Under this circumstance, the so-called Brazier effect refers to the cross-sectional ovalization, which leads to nonlinear bending buckling and collapses. This paper studies the Brazier effect by the nonlinear Variational Asymptotic Beam Sectional Analysis (VABS) theory which considers finite cross-sectional deformations. Nonlinear VABS reduces three-dimensional (3D) continuum to a one-dimensional (1D) beam analysis and a two-dimensional (2D) cross-sectional analysis featuring both geometric and material nonlinearities without unnecessary kinematic assumptions. The present theory is implemented using the finite element method (FEM) in the VABS code, a general-purpose beam cross-sectional analysis tool. An iterative method is applied to solve the finite warping field for the classical-type model using the Euler–Bernoulli beam theory. The deformation gradient tensor is directly used to deal with finite deformation, various strain definitions, and several types of material laws regarding nonlinear elasticity and progressive damage. Numerical examples demonstrate the capabilities of VABS to predict the sectional collapse of thin-walled structures under pure bending.

Brazier(1927)发现,当梁截面的一个维度相对小于其他维度时,即使应变可以保持很小,截面上也可能发生较大的面内位移。在这种情况下,所谓的火盆效应是指截面椭圆化,导致非线性弯曲屈曲和破坏。本文采用考虑有限截面变形的非线性变分渐近梁截面分析(VABS)理论研究了火盆效应。非线性VABS将三维(3D)连续体简化为一维(1D)梁分析和二维(2D)截面分析,具有几何和材料非线性,无需不必要的运动学假设。本理论是用通用梁截面分析工具VABS代码中的有限元方法实现的。利用欧拉-伯努利梁理论,采用迭代法求解经典型模型的有限翘曲场。变形梯度张量直接用于处理有限变形、各种应变定义以及几种关于非线性弹性和渐进损伤的材料规律。数值算例验证了VABS预测薄壁结构在纯弯曲作用下截面倒塌的能力。


Vibration analysis of rotating variable-angle-tow composite cylindrical structures via high-fidelity shell models

R. Azzara, M. Filippi, E. Carrera

doi:10.1016/j.tws.2024.112446

基于高保真壳模型的旋转变角-拖拽复合圆柱结构振动分析

The paper focuses on rotordynamics analyses of various rotating variable-angle-tow (VAT) composite cylindrical structures using both low- and high-fidelity structural models. To model the spatially varying composite shell structures, the Carrera Unified Formulation (CUF) is employed. The CUF provides a hierarchical and automated approach for developing shell finite element models. Various shell models are created using different kinematics models based on Taylor or Lagrange expansion functions. The linearized equations of motion include the Coriolis and initial stress contributions. Several VAT composite curved panels and thin and thick cylinders have been analyzed to validate the presented approach and provide benchmark solutions. The results are discussed and compared with commercial software solutions. The results demonstrate the good accuracy and reliability of the proposed numerical methodology.

本文采用高保真和低保真两种结构模型对各种旋转变角拖缆(VAT)复合圆柱结构进行了旋转动力学分析。为了模拟空间变化的复合材料壳结构,采用了Carrera统一公式(CUF)。CUF为开发壳体有限元模型提供了一种分层和自动化的方法。使用基于泰勒或拉格朗日展开函数的不同运动学模型创建各种壳模型。线性化的运动方程包括科里奥利和初始应力贡献。对几种VAT复合材料曲面板和厚、薄圆柱体进行了分析,验证了所提出的方法,并提供了基准解决方案。对结果进行了讨论,并与商业软件解决方案进行了比较。结果表明,所提出的数值方法具有较高的精度和可靠性。


Optimizing microstructure and strength of CMT-wire arc additive manufactured WE43 Mg alloy through a novel active cooling technique

Kun Li, Benxiang Li, Liang Zhu, Xuru Hou, Ziche Li, Lawrence E. Murr, Bing Jiang, Fusheng Pan

doi:10.1016/j.tws.2024.112453

采用新型主动冷却技术优化cmt电弧添加剂制备WE43镁合金的组织和强度

Cold metal transfer (CMT)-Wire arc additive manufacturing (WAAM) has been widely utilized in the production of large Magnesium (Mg) alloy components. However, the thermal cycling and heat input inherent in the CMT-WAAM process can adversely affect the microstructure and properties of Mg-Rare earth (RE) alloys. Currently, there is a lack of effective, low-cost, and easy-to-implement methods to mitigate these issues. In this study, an active cooling technique (ACT) comprising base cooling and bypass cooling was proposed. The ACT facilitates in-situ cooling of CMT-WAAMed WE43 components through uninterrupted water flow in the substrate and bypass plate, offering advantages in cost-effectiveness, safety, and ease of implementation. It was found that the CMT-WAAMed WE43 alloy thin wall component manufactured with the ACT assistance had fewer hard-brittle eutectic phases and finer grains due to the accelerated cooling rate. ACT effectively reduced the heat accumulation and peak temperatures in the component. Furthermore, it inhibited the transformation of the β1 phase to the β phase and suppressed the coarsening of the β1 phase. ACT also improved the ultimate tensile strength (UTS), yield strength (YS), and elongation (EL) of the CMT-WAAMed WE43 component by 11.7%, 5.8%, and 72.3%, respectively. This study provides a novel approach for the microstructure optimization of CMT-WAAMed Mg-RE alloy, which is crucial for the production of high-performance and large-size components in the aerospace industry.

冷金属转移-电弧增材制造技术在大型镁合金部件的生产中得到了广泛的应用。然而,CMT-WAAM过程中固有的热循环和热输入会对mg -稀土(RE)合金的组织和性能产生不利影响。目前,缺乏有效、低成本和易于实现的方法来缓解这些问题。在本研究中,提出了一种由基础冷却和旁路冷却组成的主动冷却技术(ACT)。ACT通过基板和旁通板中不间断的水流,促进CMT-WAAMed WE43组件的原位冷却,具有成本效益,安全性和易于实施的优势。结果表明,在ACT辅助下制备的CMT-WAAMed WE43合金薄壁件由于冷却速度加快,其硬脆共晶相减少,晶粒细化。ACT有效地降低了组件的热积累和峰值温度。抑制β1相向β相转变,抑制β1相粗化。ACT还使CMT-WAAMed WE43构件的极限抗拉强度(UTS)、屈服强度(YS)和伸长率(EL)分别提高了11.7%、5.8%和72.3%。该研究为CMT-WAAMed Mg-RE合金的微观结构优化提供了一种新的方法,这对于航空航天工业中高性能和大尺寸部件的生产至关重要。




来源:复合材料力学仿真Composites FEM
ACTMechanicalAdditiveSystemFlux静力学振动疲劳断裂复合材料非线性通用航空航天增材裂纹理论化机材料
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【新文速递】2024年9月6日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 1 篇,Mechanics of Materials 2 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 2 篇International Journal of Solids and StructuresA “poor-man’s” deformation plasticity based approach to topology optimization of elastoplastic structuresKai Li, Mathias Wallin, Matti Ristinmaa, Gengdong Chengdoi:10.1016/j.ijsolstr.2024.113056基于“穷人”变形塑性的弹塑性结构拓扑优化方法This paper presents a topology optimization framework utilizing a deformation plasticity model to approximate the isotropic hardening von-Mises incremental elastoplasticity model under monotone proportional loading. One advantage of the model is that it is based on a yield surface allowing for precise matching to uniaxial elastoplastic isotropic hardening response. The deformation plasticity model and the incremental plasticity model coincides for proportional loading and since the deformation plasticity model is path-independent, the computational cost and implementation complexity reduce significantly compared to the conventional incremental elastoplasticity. To investigate the deformation plasticity model combined with topology optimization, we compare three common elastoplastic optimization objectives: stiffness, strain energy and plastic work. The possibility to limit the peak local plastic work while maximizing the strain energy is also investigated. The consistent analytical sensitivity analysis which only requires the terminal state is derived using adjoint method. Numerical examples demonstrate that the proportionality assumption is reasonable and the deformation plasticity model combined with topology optimization is a competitive alternative to cumbersome incremental elastoplasticity.本文提出了一种利用变形塑性模型近似单调比例加载下各向同性硬化von-Mises增量弹塑性模型的拓扑优化框架。该模型的一个优点是,它是基于屈服面,允许精确匹配的单轴弹塑性各向同性硬化响应。在比例加载条件下,变形塑性模型与增量塑性模型吻合,且由于变形塑性模型与路径无关,与传统增量弹塑性模型相比,计算成本和实现复杂度显著降低。为了研究与拓扑优化相结合的变形塑性模型,我们比较了三种常用的弹塑性优化目标:刚度、应变能和塑性功。在最大限度地提高应变能的同时限制局部塑性功峰值的可能性也进行了研究。利用伴随法导出了只要求终端态的一致性分析灵敏度分析。数值算例表明,比例假设是合理的,结合拓扑优化的变形塑性模型是替代繁琐的增量弹塑性的有力选择。Mechanics of MaterialsPhysically recurrent neural network for rate and path-dependent heterogeneous materials in a finite strain frameworkM.A. Maia, I.B.C.M. Rocha, D. Kovačević, F.P. van der Meerdoi:10.1016/j.mechmat.2024.105145在有限应变框架下速率和路径相关非均质材料的物理递归神经网络In this work, a hybrid physics-based data-driven surrogate model for the microscale analysis of heterogeneous material is investigated. The proposed model benefits from the physics-based knowledge contained in the constitutive models used in the full-order micromodel by embedding the material models in a neural network. Following previous developments, this paper extends the applicability of the physically recurrent neural network (PRNN) by introducing an architecture suitable for rate-dependent materials in a finite strain framework. In this model, the homogenized deformation gradient of the micromodel is encoded into a set of deformation gradients serving as input to the embedded constitutive models. These constitutive models compute stresses, which are combined in a decoder to predict the homogenized stress, such that the internal variables of the history-dependent constitutive models naturally provide physics-based memory for the network. To demonstrate the capabilities of the surrogate model, we consider a unidirectional composite micromodel with transversely isotropic elastic fibers and elasto-viscoplastic matrix material. The extrapolation properties of the surrogate model trained to replace such micromodel are tested on loading scenarios unseen during training, ranging from different strain-rates to cyclic loading and relaxation. Speed-ups of three orders of magnitude with respect to the runtime of the original micromodel are obtained.在这项工作中,研究了一种基于混合物理的数据驱动代理模型,用于非均质材料的微尺度分析。该模型通过将材料模型嵌入到神经网络中,利用全阶微模型中本构模型中包含的物理知识。根据先前的发展,本文通过在有限应变框架中引入适用于速率相关材料的架构,扩展了物理递归神经网络(PRNN)的适用性。该模型将微模型的均匀化变形梯度编码为一组变形梯度,作为嵌入本构模型的输入。这些本构模型计算应力,这些应力组合在一个解码器中以预测均匀的应力,这样,依赖于历史的本构模型的内部变量自然地为网络提供基于物理的记忆。为了证明替代模型的能力,我们考虑了一个具有横向各向同性弹性纤维和弹粘塑性基体材料的单向复合微模型。在训练期间未见的加载场景下,从不同的应变率到循环加载和松弛,测试了替代微模型的替代模型的外推特性。相对于原始微模型的运行时间,获得了三个数量级的加速。Effect of porous microstructure and fiber arrangement of thermal protection composites on effective thermal conductivityFan Yang, Weihua Xie, Songhe Mengdoi:10.1016/j.mechmat.2024.105147热防护复合材料的孔隙结构和纤维排列对有效导热系数的影响The inclusions in a high-temperature resistant matrix can significantly influence the radiative heat transfer of composite materials at elevated temperatures; therefore, the microstructure design of composites for thermal protection during atmospheric re-entry require a more accurate prediction of thermal insulation performance. In this paper, the Rosseland approximation was used to investigate the radiative heat transfer within thermal protection materials, e.g., porous carbon-based material and ultra-high-temperature ceramics (e.g., ZrB2-SiC), and the discrete dipole scattering method was used to evaluate the extinction efficiency across the inclusions with different types of microstructures. The effect of inclusion parameters, such as inclusion size, shape coefficient, volume fraction, orientation, and size distribution, on the radiative and effective thermal conductivity (ETC) at various temperatures was analyzed in detail. Test results obtained from the existing literature were used to validate the ETC of porous ceramics predicted by the proposed model. The results indicated that the microstructures in thermal protection materials play a fundamental role in improving the heat-shielding properties. The present study deepens the understanding of the relationship between microstructures and thermal radiation properties and provides theoretical design guidelines for thermal protection materials with improved thermal insulation properties.耐高温基体中的夹杂物对复合材料在高温下的辐射传热有显著影响;因此,用于大气再入热防护的复合材料微结构设计需要对其隔热性能进行更精确的预测。本文采用Rosseland近似研究了多孔碳基材料和超高温陶瓷(如ZrB2-SiC)等热防护材料内部的辐射传热,并采用离散偶极子散射方法评估了不同类型显微结构夹杂间的消光效率。详细分析了包裹体尺寸、形状系数、体积分数、取向、尺寸分布等参数对不同温度下的辐射导热系数和有效导热系数的影响。利用现有文献的测试结果验证了所提出模型预测的多孔陶瓷的ETC。结果表明,热防护材料的显微组织对热防护性能的提高起着至关重要的作用。本研究加深了对微结构与热辐射性能关系的认识,为提高隔热性能的热防护材料的设计提供了理论指导。International Journal of PlasticityInfluence of textural variability on plastic response of porous crystal embedded in polycrystalline aggregate: A crystal plasticity studySagar Chandra, Suranjit Kumar, Mahendra K. Samal, Vivek M. Chavandoi:10.1016/j.ijplas.2024.104117多晶骨料中嵌入多孔晶体的织构变化对塑性响应的影响:晶体塑性研究Damage evolution in polycrystalline aggregates is complicated by the intricate interplay of crystallographic orientation of the porous grain and the surrounding anisotropic matrix. Therefore, formulation of design rules and damage models for polycrystalline materials proves daunting due to relative lack of thorough understanding of the underlying heterogeneity at the mesoscale. This work explores the orientation dependent void growth in a porous crystal embedded in an anisotropic polycrystalline matrix with different initial textures. Polycrystalline face-centered cubic based aggregate is simulated within the framework of crystal plasticity finite element method. Porosity is first modeled in the form of a single pre-existing spherical void in the central grain of the randomly oriented polycrystal. One-hundred crystallographic orientations of the central grain in three-dimensional Euler space are analyzed to reveal the orientation dependent trends of the porous grain. To account for textural variability, the analysis is repeated for polycrystals exhibiting preferred textures like Cube, Brass, Copper and Goss. In this manner, interesting orientation dependent trends in basic tenets of void growth like yield strength, coalescence strain and porosity evolution are unraveled across various polycrystalline textures. To account for spatial heterogeneity as well, porosity in the central grain is then re-distributed and the aforementioned analysis is repeated for all the crystallographic orientations of the central grain embedded in polycrystals with different textures. Owing to the large amount of data thus generated, statistical analysis is invoked to identify stimulating trends and key statistical variables governing the strength and toughness. Consequently, a statistical void growth model is also presented by assessing the CP simulation results and identifying suitable distribution function governing the growth of voids in polycrystals. The modeling framework is expected to inform porous plasticity models aimed at capturing damage evolution in porous grains embedded in polycrystalline materials exhibiting topological and crystallographic anisotropy.多孔颗粒的晶体取向与周围各向异性基体的相互作用使多晶团聚体的损伤演化变得复杂。因此,由于相对缺乏对中尺度潜在非均质性的透彻理解,多晶材料的设计规则和损伤模型的制定是艰巨的。本研究探索了嵌入在具有不同初始结构的各向异性多晶基质中的多孔晶体中与取向相关的空洞生长。采用晶体塑性有限元法对多晶面心立方基骨料进行了数值模拟。孔隙度首先以随机取向多晶的中心颗粒中单个预先存在的球形空隙的形式建模。对中心晶粒在三维欧拉空间的100个晶体取向进行了分析,揭示了多孔晶粒的取向依赖趋势。为了解释纹理的可变性,对具有立方体、黄铜、铜和高斯等优选纹理的多晶重复分析。通过这种方式,在不同的多晶结构中揭示了屈服强度、聚结应变和孔隙度演化等空洞生长基本原理中有趣的取向依赖趋势。为了考虑空间异质性,中心晶粒的孔隙度被重新分配,并对嵌入在不同纹理的多晶体中的中心晶粒的所有晶体取向重复上述分析。由于产生了大量的数据,因此需要进行统计分析,以确定刺 激的趋势和控制强度和韧性的关键统计变量。在此基础上,通过对CP模拟结果的评估,确定了控制多晶中孔洞生长的合适分布函数,提出了孔洞生长的统计模型。该模型框架有望为多孔塑性模型提供信息,这些模型旨在捕捉嵌入在具有拓扑和晶体各向异性的多晶材料中的多孔颗粒的损伤演变。Thin-Walled StructuresFree vibration analysis of a functionally graded porous triangular plate with arbitrary shape and elastic boundary conditions using an isogeometric approachMilad Izadi, Maryam Abedi, Paolo S. Valvodoi:10.1016/j.tws.2024.112422用等几何方法分析任意形状和弹性边界条件下功能梯度多孔三角形板的自由振动This paper presents a comprehensive analysis of the free vibrations of functionally graded porous (FGP) triangular plates with arbitrary shapes and elastic boundary conditions using Isogeometric Analysis (IGA). We express the triangular shapes by using non-uniform rational B-splines (NURBS). The impact of porosity, geometry, and boundary conditions on the natural frequencies is investigated, with a focus on three key factors: porosity coefficient, geometric shape, and type of boundary conditions. Results show that increasing porosity generally leads to an increase in natural frequencies for thin plates, while thicker plates exhibit the opposite trend. The effect of geometric shape, characterized by different angles, is investigated and reveals distinct trends in natural frequencies. The study also investigates both classical and elastic boundary conditions, illustrating the impact of arbitrary boundary conditions on the natural frequency response. Validation against previous references and finite element methods establishes the accuracy of the presented results. The paper concludes with an extension of the analysis to various scenarios, offering valuable insights into the intricate interplay of porosity, geometry, and boundary conditions on the vibrational behavior of FGP triangular plates.本文采用等几何分析方法对具有任意形状和弹性边界条件的功能梯度多孔(FGP)三角形板的自由振动进行了综合分析。用非均匀有理b样条(NURBS)表示三角形。研究了孔隙度、几何形状和边界条件对固有频率的影响,重点研究了孔隙度系数、几何形状和边界条件类型这三个关键因素。结果表明,孔隙率的增加通常会导致薄板固有频率的增加,而厚板则相反。研究了不同角度的几何形状的影响,揭示了固有频率的不同趋势。该研究还研究了经典边界条件和弹性边界条件,说明了任意边界条件对固有频率响应的影响。通过对先前文献和有限元方法的验证,确定了所提出结果的准确性。本文最后将分析扩展到各种情况,为FGP三角形板的振动行为的孔隙率,几何形状和边界条件的复杂相互作用提供了有价值的见解。On energy absorption capability and controllable failure modes of CFRP circular tube using numerical simulationHongyuan Yang, Yiru Rendoi:10.1016/j.tws.2024.112423 基于数值模拟的CFRP圆管能量吸收能力及可控失效模式研究Enhancing the energy absorption (EA) capacity of carbon fiber reinforced plastic (CFRP) structures by inducing controlled failure modes is significant for lightweight design in aerospace. In the present work, four triggers including inward horizontal trigger, inward tilted trigger, outward horizontal trigger and outward tilted trigger are proposed to induce specific failure modes of CFRP circular tubes under axial loading. Under the framework of maximum stress and traction-separation damage criterion, the numerical model that can accurately predict load response and fracture behavior is established. The results showed that circular tubes with horizontal triggers have higher energy absorption (0.98%–15.62%). The circular tubes with tilted triggers were able to achieve higher crushing load efficiency (12.16%–22.97%). The damage state of the material becomes controllable and mainly manifests as tensile and compressive damage in the axial fiber direction. To clarify the strengthening mechanism, the influence of typical structural parameters of the trigger on the crashworthiness is investigated. It is found that increasing the groove width can effectively reduce the peak load. Finally, the controlled failure principle of CFRP tubes is analyzed and revealed. The results confirm the effectiveness of the trigger mechanism.通过诱导可控失效模式来提高碳纤维增强塑料(CFRP)结构的吸能能力,对航空航天轻量化设计具有重要意义。本文提出了向内水平触发、向内倾斜触发、向外水平触发和向外倾斜触发四种触发机制来诱导CFRP圆管在轴向载荷作用下的特定破坏模式。在最大应力和牵引分离损伤准则框架下,建立了能够准确预测载荷响应和断裂行为的数值模型。结果表明,带水平触发装置的圆管吸能较高(0.98% ~ 15.62%)。带倾斜触发器的圆管具有较高的破碎负荷效率(12.16% ~ 22.97%)。材料的损伤状态变得可控,主要表现为纤维轴向的拉伸和压缩损伤。为阐明其强化机理,研究了触发器典型结构参数对其耐撞性的影响。研究发现,增大槽宽可以有效降低峰值荷载。最后,分析并揭示了CFRP管的可控失效原理。结果证实了该触发机构的有效性。来源:复合材料力学仿真Composites FEM

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