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【新文速递】2024年5月24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 1 篇,Journal of the Mechanics and Physics of Solids 1 篇,Thin-Walled Structures 6 篇

International Journal of Solids and Structures

Finite strain modelling of shape memory alloys in the logarithmic strain space: A comparative study with other finite strain approaches

Saswata Chattopadhyay, Lucas A. Woodworth, Michael Kaliske

doi:10.1016/j.ijsolstr.2024.112892

对数应变空间中形状记忆合金的有限应变建模:与其他有限应变方法的比较研究

Finite strain models for Shape Memory Alloys (SMAs) offer significant advantages over small strain models in that they excel in their ability to characterise SMA behaviour under large strain and finite rotations while eliminating the inherent assumptions associated with the small strain framework. The paper at hand presents a numerical model for SMAs at finite strain, employing the logarithmic strain measure to obtain an additive split of the total strain into its elastic and inelastic (transformation) parts. Notably, the model maintains the thermodynamic consistency validated using the Clausis-Duhem inequality. Additionally, we compare this model with two other finite strain SMA models employing logarithmic strain measures: a hypoelastic model, which splits the rate of deformation tensor additively, and a hyperelastic model, which decomposes the deformation gradient multiplicatively. The numerical formulation for the three finite strain models is specifically tailored to address superelasticity in SMAs. It is derived from the established small strain model and seamlessly extended into the domain of finite strain framework. Several numerical examples are carried out to showcase the logarithmic strain space approach applied to SMAs and to compare its response with that of the other aforementioned finite strain models in SMAs. The meticulous examination reveals that the logarithmic strain space approach aligns well with the existing finite strain models, demonstrating its effectiveness and compatibility.

形状记忆合金(SMA)的有限应变模型比小应变模型具有显著的优势,因为它们在描述大应变和有限旋转下SMA行为的能力方面表现出色,同时消除了与小应变框架相关的固有假设。本文提出了有限应变下sma的数值模型,采用对数应变测度得到了总应变在弹性和非弹性(转换)部分的加性分裂。值得注意的是,该模型保持了使用Clausis-Duhem不等式验证的热力学一致性。此外,我们将该模型与另外两种采用对数应变测量的有限应变SMA模型进行了比较:一种是将变形张量速率相加的低弹性模型,另一种是将变形梯度相乘分解的超弹性模型。三种有限应变模型的数值公式是专门为解决sma中的超弹性而量身定制的。它是从已有的小应变模型中衍生出来的,并无缝地扩展到有限应变框架领域。通过几个数值算例,展示了对数应变空间方法在sma中的应用,并将其与上述其他有限应变模型的响应进行了比较。结果表明,对数应变空间方法与现有的有限应变模型吻合良好,证明了其有效性和兼容性。


Journal of the Mechanics and Physics of Solids

Phase-field model for 2D cohesive-frictional shear fracture: An energetic formulation

Ye Feng, Francesco Freddi, Jie Li, Yu E. Ma

doi:10.1016/j.jmps.2024.105687

二维黏结-摩擦剪切断裂的相场模型:一个能量公式

This paper presents a phase-field model for cohesive-frictional shear fracture. The model is derived based on two energetic principles: the energy conservation law and a variational inequality of virtual work that serves as a stability condition. We show that all the governing equations for frictional fracture can be obtained from the above two principles, including the equilibrium condition, the phase-field evolution law and, most importantly, the yield function and flow rule for the plasticity-like frictional slip. The information of crack direction is naturally included in the flow rule. Theoretical and numerical results show that the proposed model is faithfully consistent with the Mohr–Coulomb theory of frictional failure in terms of the crack nucleation stress and direction. In addition, the presented phase-field model has an explicit frictional cohesive law.

本文提出了黏结-摩擦剪切断裂的相场模型。该模型基于两个能量原理:能量守恒定律和作为稳定条件的虚功的变分不等式。结果表明,上述两种原理均可得到摩擦断裂的控制方程,包括平衡条件、相场演化规律,以及最重要的类塑性摩擦滑移的屈服函数和流动规律。裂纹方向信息自然包含在流动规律中。理论和数值结果表明,该模型在裂纹形核应力和方向上与Mohr-Coulomb摩擦破坏理论完全一致。此外,所提出的相场模型具有明确的摩擦内聚规律。


Thin-Walled Structures

Three-dimensional hygro-thermo-mechanical bending analysis of anisotropic skewed parallelogram plates on a tri-parameter foundation using a wavelet method

Qiang Yu, Junfeng Xiao, Hang Xu

doi:10.1016/j.tws.2024.112006

基于三参数基础的各向异性倾斜平行四边形板三维水热力学弯曲分析

In the paper, a brand-new three-dimensional hygro-thermo-mechanical bending model of anisotropic skewed parallelogram plates with extreme skew angle in large deformation supported by a tri-parameter nonlinear elastic foundation is proposed. By investigating the mutual coupled interaction of hygrothermal effects between in-plane distribution and thickness variation, nine kinds of spatially analytical hygrothermal fields in parallelogram domain are established by analyzing the Dirichlet, Neumann and Robin thermal boundary conditions of sinusoidally induced heat conduction at top and bottom surfaces. With coordinate transformation in oblique system considering the Von Kármán membrane strains, the highly coupled and strongly nonlinear governing partial differential equations have been derived. A wavelet solving procedure has been developed with the convergence process validated and precision of obtained solutions verified in good accordance with published results. Parametric studies have been carried out to investigate the large-deflection behavior of simply supported or clamped skew plates on Winkler-Pasternak foundation under combined mechanical and hygrothermal loads. The influence of skew angle, material orthotropy and foundation contact nonlinearity is examined, which reveals the geometrically nonlinear responses of plates are highly affected by large oblique angle, principle orientation of material orthotropy and foundation parameters.

本文提出了三参数非线性弹性地基支撑的各向异性极斜角平行四边形板在大变形条件下的全新三维水热力学弯曲模型。通过对上下表面正弦诱导热传导的Dirichlet、Neumann和Robin热边界条件的分析,建立了平行四边形域中9种空间解析型热场,研究了平面内分布与厚度变化之间的热效应相互耦合作用。在考虑Von Kármán膜应变的斜坐标系下进行坐标变换,导出了高耦合、强非线性的控制偏微分方程。提出了一种小波求解方法,并验证了该方法的收敛性,得到的解的精度与已发表的结果一致。对温克勒-帕斯捷尔纳克基础上简支或夹紧斜板在机械和湿热联合荷载作用下的大挠度行为进行了参数化研究。分析了斜倾角、材料各向异性和基础接触非线性对板的几何非线性响应的影响,表明大斜倾角、材料各向异性主取向和基础参数对板的几何非线性响应影响较大。


Meshing behavior assessment methods for hybrid metal-composite gears with anisotropic and quasi-isotropic webs

Zhou Sun, Siyu Chen, Jinyuan Tang, Zehua Hu, Xuan Tao, Duncai Lei, Hongtao Dong

doi:10.1016/j.tws.2024.112031

具有各向异性和准各向同性腹板的混合金属-复合齿轮啮合行为评估方法

Thin-web structures are the primary strategy for lightweight gears in the aerospace and automotive fields, but current research mainly focuses on metal thin web, lacking understanding of the application of anisotropic and quasi-isotropic composite thin-web gears. Focusing on accurate and efficient calculations of mesh stiffness and load sharing ratio, this work develops a unified numerical analysis method to assess the meshing behavior of the two hybrid metal-composite gears. Multi-scale numerical prediction methods for elastic properties of anisotropic composite and homogeneous laminated webs are established, and two tooth-loading deformation calculation methods for metal-composite-metal gear bodies with different web widths are developed separately. A numerical analysis method is proposed by unifying the iterative calculation process of the two hybrid gears through deformation coordination relationships, which is also applicable to full metal gears. Finally, extensive comparisons with the finite element method (FEM) and existing numerical method verify the proposed analytical method (PAM). The investigation results reveal the impact of replacing full metal gears with these two hybrid gears on the meshing behavior and further elucidate the advantages of using composite webs for micro and macro parameters design in adjusting the mass and stiffness and reducing mesh stiffness fluctuations. This work provides a new analytical method for the structural design and performance assessment of lightweight hybrid metal-composite gear systems.

薄腹板结构是航空航天和汽车领域轻量化齿轮的主要策略,但目前的研究主要集中在金属薄腹板上,缺乏对各向异性和准各向同性复合薄腹板齿轮应用的了解。着眼于准确、高效地计算啮合刚度和载荷分担比,本文开发了一种统一的数值分析方法来评估两个金属-复合材料混合齿轮的啮合性能。建立了各向异性复合材料和均匀层合腹板弹性性能的多尺度数值预测方法,分别开发了两种不同腹板宽度的金属-复合-金属齿轮体齿载变形计算方法。通过变形协调关系统一了两种混合齿轮的迭代计算过程,提出了一种数值分析方法,该方法同样适用于全金属齿轮。最后,通过与有限元法(FEM)和现有数值方法的比较,验证了所提出的解析法(PAM)的有效性。研究结果揭示了用这两种混合齿轮代替全金属齿轮对啮合性能的影响,进一步阐明了采用复合腹板进行微观和宏观参数设计在调节质量和刚度、减小啮合刚度波动方面的优势。为轻量化金属复合材料混合齿轮系统的结构设计和性能评价提供了一种新的分析方法。


Design and Analysis of a Solid Surface Deployable Antenna Mechanism Based on Flasher Rigid Origami

Dake Tian, Xihua Yang, Lu Jin, Zuwei Shi, Hongwei Guo, Rongqiang Liu

doi:10.1016/j.tws.2024.112033

基于Flasher刚性折纸的固体表面可展开天线机构设计与分析

This study proposes a mechanism for solid surface deployable antennas based on flasher rigid origami. The mechanism scheme design and degree-of-freedom analysis were conducted utilizing a Kirigami release constraint strategy. Subsequently, a spatial geometric model of the key points was established incorporating the folding and unfolding characteristics and geometric relationships within the mechanism. Furthermore, a comprehensive 3D model of the antenna was developed by determining the hinge locations, geometric parameters, and driving mechanism, followed by a kinematic simulation analysis. Finally, a prototype was constructed, and a microgravity deployment experiment was conducted to verify the feasibility of the mechanism.

本研究提出了一种基于闪光刚性折纸的固体表面可展开天线机制。采用Kirigami释放约束策略进行了机构方案设计和自由度分析。随后,结合机构内部的折叠展开特性和几何关系,建立了关键点的空间几何模型。通过确定天线的铰链位置、几何参数和驱动机构,建立了天线的三维模型,并进行了运动学仿真分析。最后,搭建了原型机,并进行了微重力展开实验,验证了该机构的可行性。


Anti-plane dynamic response characteristics of a semi-infinite plate with cylindrical hole defect

Fan Zhiyu, Qi Hui, Zhang Yufeng, Wu Hao, Chu Fuqing, Guo Jing

doi:10.1016/j.tws.2024.112038

半无限圆孔缺陷板的反平面动力响应特性

The semi-infinite thin plate structure, widely used in aerospace industry devices and spliced functional composites, fails to meet the dynamic response performance and stability requirements due to the dynamic stress concentration or displacement mutation caused by the structure boundary and internal defect under specific external dynamic loads. This study has established an analytical method for the dynamic response characteristics in steady-state frequency-domain and transient time-domain of a semi-infinite thin plate with a cylindrical hole under the excitation of external anti-plane dynamic loads. Based on the wave function expansion method, cumulative mirroring method, and complex variable function method, the distribution of dynamic stress concentration and displacement amplitude under steady-state anti-plane excitation has been given. Based on the Fourier transform and inverse Fourier transform, the analysis of dynamic response behavior under transient anti-plane excitation has been given. Numerical results indicate that the coupled scattered waves generated by multiple boundaries will cancel and amplify the dynamic stress and displacement amplitude within the plate under different parameter combinations, leading to the dynamic stress concentration and displacement mutation of the structure. Therefore, reasonable structural design optimization will benefit the dynamic response performance and stability requirements of the structure.

广泛应用于航空航天工业器件和拼接功能复合材料的半无限薄板结构,在特定的外部动载荷作用下,由于结构边界和内部缺陷引起的动应力集中或位移突变,不能满足动态响应性能和稳定性要求。建立了外反平面动载荷作用下带圆柱孔的半无限薄板在稳态频域和瞬态时域的动态响应特性分析方法。基于波函数展开法、累积镜像法和复变函数法,给出了稳态反平面激励下动应力集中和位移幅值的分布。基于傅里叶变换和傅里叶反变换,分析了瞬态反平面激励下的动力响应特性。数值结果表明,在不同参数组合下,由多个边界产生的耦合散射波会抵消和放大板内的动应力和位移幅值,导致结构的动应力集中和位移突变。因此,合理的结构设计优化有利于结构的动力响应性能和稳定性要求。


Free vibration analysis of pre-twisted rotating dovetailed blade under the flexible connection with macro-micro rough contact topography

Hehe Kang, Zhi-Min Li, Tao Liu, Wei Yuan, Jianping Jing

doi:10.1016/j.tws.2024.112039

宏微粗糙接触地形柔性连接下预扭旋转燕尾叶片自由振动分析

The dynamic characteristic of the dovetailed blade plays a key role in the performance and service life of the whole aero-engine. Due to the current manufacturing accuracy and process, the macro-micro contact topography is random and various, which causes the change of the contact response in the blade root as well as the vibration of the blade body. In this paper, a new dynamic model of the pre-twisted rotating dovetailed blade under the flexible connection is established to investigate the free vibration of the blade with macro-micro rough contact topography. First, the elastic boundary of the blade root is quantified by the connection stiffness deduced from the rough contact theory. The governing equation of the blade is formulated by the thin shell theory, and the orthogonal polynomials are employed as the admissible displacement function to calculate the natural frequency though the Ritz method. Then, the effectiveness of the proposed model is validated by comparing it with the theoretical and experimental data. Finally, the influences of the pre-twisted angle, the rotational speed, the macroscopic geometrical deviation, and microscopic topography parameters on free vibration of the blades are investigated in detail. The results show that the natural frequencies have the crossover phenomenon as the parameters vary. The macro-micro topography parameters of the contact interface have a stronger ability to influence the frequency when the rotating speed is low than the high rotating speed. The presented work builds a bridge between the vibration characteristic of the blade body and the macro-micro rough contact topography of the dovetailed joint, which is very meaningful to guide the design of the aero-engine.

燕尾叶片的动态特性对整个航空发动机的性能和寿命起着至关重要的作用。由于目前的制造精度和工艺,宏观微观接触形貌是随机的、多样的,这导致了叶根接触响应的变化以及叶体的振动。建立了柔性连接下预扭旋转燕尾叶片的动力学模型,研究了具有宏微观粗糙接触形貌的预扭旋转燕尾叶片的自由振动问题。首先,利用粗糙接触理论推导出的连接刚度对叶根的弹性边界进行量化;采用薄壳理论建立了叶片的控制方程,采用正交多项式作为允许位移函数,采用里兹法计算叶片的固有频率。然后,通过与理论和实验数据的比较,验证了所提模型的有效性。最后,详细分析了预扭角、转速、宏观几何偏差和微观形貌参数对叶片自由振动的影响。结果表明,随着参数的变化,固有频率存在交叉现象。转速较低时,接触界面的宏微观形貌参数对频率的影响能力强于转速较高时。本文所做的工作在叶体振动特性与燕尾接头宏微观粗糙接触形貌之间架起了一座桥梁,对指导航空发动机的设计具有重要意义。


Static Mechanical Properties and Failure Behaviors of Self-Piercing Riveted Joints in Aluminum Alloy 5A06 after Aging

Kai Ye, Zhao Lun, Zeshan Abbas, Chengwang Li, Gaoyu Liu, Le Lei, Jiehao Lu, Md Shafiqul Islam

doi:10.1016/j.tws.2024.112041

5A06铝合金自穿铆接接头时效后的静态力学性能及失效行为

This paper conducts an investigation on the static mechanical properties and failure behavior of self-piercing riveted joints in aluminum alloy 5A06 after being subjected to the aging process. The study involves three distinct categories of joint specimens: original specimens, 1-year aged specimens and 1-year aged specimens that have been additionally heat-treated at 200°C. The research findings affirm that strain aging is responsible for a reduction in the peak strength of the joints. Furthermore, the weakest failure chain within the self-piercing riveted joint shifts towards the upper sheet due to a more significant reduction in internal stress experienced by the upper plate. This leads to a failure model characterized by upper sheet pull-off. Through Weibull distribution analysis, it has been established that the 5% lower limit value for the strength of the SPR joint experiences an 86% decline following 1-year aging. In practical terms, this means that for a vehicle structure with 7,000 riveting points will lose an overall structural strength equivalent to the initial strength of 1,000 riveting points within one year.

研究了5A06铝合金自穿铆接接头在时效过程中的静态力学性能和失效行为。本研究涉及三种不同类型的关节试件:原始试件、1年时效试件和经200℃额外热处理的1年时效试件。研究结果证实,应变老化是导致接头峰值强度降低的主要原因。此外,自穿铆接接头内最弱的破坏链向上板移动,因为上板所经历的内应力更显著地减少。这导致了一种破坏模式,其特征是上部板的拉脱。通过Weibull分布分析可知,SPR接头强度下限为5%,时效1年后强度下降86%。实际上,这意味着对于具有7,000个铆接点的车辆结构,在一年内将失去相当于1,000个铆接点的初始强度的整体结构强度。


来源:复合材料力学仿真Composites FEM
MeshingACTMechanicalAdditiveSystem振动断裂复合材料非线性航空航天汽车裂纹理论材料多尺度控制
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首次发布时间:2024-11-14
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【新文速递】2024年5月5日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 2 篇,Mechanics of Materials 1 篇,International Journal of Plasticity 2 篇,Thin-Walled Structures 1 篇International Journal of Solids and StructuresSolitary waves in slightly dispersive quasi-incompressible hyperelastic materialsGiuseppe Saccomandi, Luigi Vergoridoi:10.1016/j.ijsolstr.2024.112861 微色散准不可压缩超弹性材料中的孤波Based on the classical theory of simple materials of differential type and the results on the analytical form of constitutive models consistent with the laws of thermodynamics, we introduce a very general response function for the Cauchy stress tensor of a dispersive hyperelastic solid. Next, by focusing on the propagation of localised waves in slightly dispersive quasi incompressible solids, we prove the existence of a rich variety of solitary wave solutions as well as kink wave solutions. Our analysis and results can be easily specialised to shape memory alloys.基于微分型简单材料的经典理论和符合热力学规律的本构模型解析形式的结果,我们引入了色散超弹性固体的柯西应力张量的一个非常一般的响应函数。接下来,通过关注局域波在微色散准不可压缩固体中的传播,我们证明了各种各样的孤立波解和扭波解的存在性。我们的分析和结果可以很容易地专门用于形状记忆合金。An exploration into surface wrinkling in 3D printing inspired orthotropic bilayer systemsMatteo Montanari, Ranim Hamaied, Chao Gao, Chiara Bertolin, Andrea Spagnolidoi:10.1016/j.ijsolstr.2024.112862 基于正交各向异性双层系统的3D打印表面起皱研究Surface instability, termed wrinkling, might occur in compressed bilayer systems constituted by an external rigid skin resting on an internal soft substrate, where wrinkling is favoured by the rigidity contrast between the two layers. In this paper, the same instability mechanism is explored by considering a substrate characterized by an orthotropic elastic response. By varying the orientation of the principal axes of the substrate’s material, the critical strain of wrinkling and the wrinkles’ wavelength can be tuned during compression. Theoretical formulations for wrinkling are discussed along with the results obtained by linear bifurcation and geometrically nonlinear analyses carried out with two-dimensional finite element models. To experimentally validate the results, the intrinsic properties of Fused Deposition Modeling (FDM) 3D printing technology are leveraged: bilayer objects are manufactured by printing continuous outer shells (corresponding to the rigid skin) along the borders, while the inner raster is shaped with a porous infill pattern, forming a substrate with an orthotropic elastic response.表面不稳定,称为起皱,可能发生在由外部刚性皮肤放在内部软基板上构成的压缩双层系统中,其中两层之间的刚性对比有利于起皱。本文通过考虑具有正交各向异性弹性响应的衬底,探讨了相同的失稳机制。通过改变衬底材料主轴的方向,可以在压缩过程中调节起皱的临界应变和起皱的波长。讨论了起皱的理论公式,以及用二维有限元模型进行线性分岔和几何非线性分析的结果。为了实验验证结果,利用了熔融沉积建模(FDM) 3D打印技术的固有特性:通过沿边界打印连续的外壳(对应于刚性皮肤)来制造双层物体,而内部光栅则形成多孔填充图案,形成具有正交异性弹性响应的基板。Mechanics of MaterialsFracture of four semi-regular lattices regulated by T-stress in modified boundary layer modelsXing Yang, Bin Zhangdoi:10.1016/j.mechmat.2024.105026修正边界层模型中受t应力调节的四个半规则晶格的断裂The development of additive manufacturing technology has promoted the rise of various lattice metamaterials, and evaluating their fracture properties is critical for both application and safety. Here, by conducting finite element simulations on four types of elastic-brittle semi-regular lattices (kagome, snub-trihexagonal, elongated-triangular, and snub-square), we indicate that the fracture toughness of lattice metamaterials is not solely determined by the crack-tip singular term, i.e., the critical stress intensity factor, but is also influenced by the non-singular T-stress term. T-stress regulates fracture toughness by modulating geometrical distortions and force-carrying modes of lattice bars around the crack front. This regulation effect depends on the lattice topology and becomes weaker under mixed-mode loading. As the relative density of lattices decreases, T-stress can force elastic buckling of bars around the crack front, which may deteriorate the fracture toughness. Additionally, positive T-stress tends to promote the crack deflection and negative T-stress tends to inhibit. Our results offer new insights into the structure-property relationships in the presence of T-stress, which may contribute to design the geometry of micro/nano-lattice metamaterials.增材制造技术的发展促进了各种晶格超材料的兴起,对其断裂性能的评估对其应用和安全性至关重要。通过对四种类型的弹脆半规则晶格(kagome、snub- tri六边形、细长三角形和snub-正方形)进行有限元模拟,我们发现晶格超材料的断裂韧性不仅由裂纹尖端奇异项即临界应力强度因子决定,而且还受到非奇异t应力项的影响。t应力通过调节裂纹前缘晶格条的几何变形和受力模式来调节断裂韧性。这种调节效应依赖于晶格拓扑结构,在混合模式加载下减弱。随着晶格相对密度的减小,t应力会使裂纹前缘周围的杆件发生弹性屈曲,从而降低断裂韧性。正t应力有促进裂纹变形的趋势,负t应力有抑制裂纹变形的趋势。我们的研究结果为t应力存在下的结构-性能关系提供了新的见解,这可能有助于设计微/纳米晶格超材料的几何形状。International Journal of PlasticityAtomistic to continuum mechanics description of crystal defects with dislocation density fields: Application to dislocations and grain boundariesHoussam Kharouji, Lucile Dezerald, Pierre Hirel, Philippe Carrez, Patrick Cordier, Vincent Taupin, Julien Guénolédoi:10.1016/j.ijplas.2024.103990具有位错密度场的晶体缺陷的原子-连续介质力学描述:位错和晶界的应用The atomic structure of crystal defects such as dislocations, grain or phase boundaries, control these defects’ properties: their mobility, ability to cross-slip, or solute segregation. These crystal defects can be conveniently studied by atomistic simulations and one then needs to transfer relevant information at the upper scale to model microstructures containing a large number of defects, e.g., a polycrystal. Here, we propose an atomistic to continuum mechanics crossover method that (i) represents the atomic structure of dislocations cores by an appropriate Nye dislocation density tensor field and (ii), captures quantitatively the short and long range mechanical fields of defects. For (i), we propose a modified and improved interpolation method based on the original work by Hartley and Mishin. For (ii), we use a field dislocation mechanics framework that rigorously calculates/evaluates the mechanical fields associated with any Nye dislocation density distribution. The transfer method relies on molecular static calculations using two energetic models - ab-initio for screw dislocation core simulations in tungsten, and EAM potential for low and large angle grain boundaries in copper. Our findings demonstrate the effectiveness of the proposed approach in reconstructing the Burgers vector, and continuous strain and rotation fields. The framework is further applied to analyze the elastic interactions between extrinsic edge dislocations and a low angle grain boundary in copper.晶体缺陷的原子结构,如位错、晶粒或相边界,控制着这些缺陷的性质:它们的迁移率、交叉滑移能力或溶质偏析。这些晶体缺陷可以通过原子模拟来方便地研究,然后需要在较高的尺度上传递相关信息来模拟包含大量缺陷的微观结构,例如多晶。在这里,我们提出了一种原子与连续介质力学交叉方法,该方法(i)通过适当的奈位错密度张量场表示位错核心的原子结构,(ii)定量捕获缺陷的短期和长期力学场。对于(i),我们在Hartley和Mishin的原始工作的基础上提出了一种改进的插值方法。对于(ii),我们使用场位错力学框架,严格计算/评估与任何Nye位错密度分布相关的力学场。传递方法依赖于两种能量模型的分子静力计算,一种是用于钨中螺位错核模拟的abi -initio模型,另一种是用于铜中低角和大角晶界的EAM势模型。我们的发现证明了所提出的方法在重建汉堡矢量,连续应变和旋转场方面的有效性。该框架进一步应用于分析铜中外源边缘位错与低角晶界之间的弹性相互作用。Synergistic grain boundary engineering for achieving strength-ductility balance in ultrafine-grained high-Cr-bearing multicomponent alloysXiaoming Liu, Kaikai Song, Zongde Kou, Jianhong Gong, Xiangyan Chen, Qingwei Gao, Hui Sun, Pingping Liu, Ruitao Qu, Lina Hu, Zequn Zhang, Parthiban Ramasamy, Zengqian Liu, Zhenjun Zhang, Feng Liu, Zhefeng Zhang, Jürgen Eckertdoi:10.1016/j.ijplas.2024.103992 实现超细晶高含铬多组分合金强度-塑性平衡的协同晶界工程Precipitation strengthening is a crucial strategy for ensuring the overall performance of conventional and multicomponent alloys to meet industrial demands. However, the mechanical properties of high-Cr-bearing alloys are often compromised by brittle Cr-rich precipitates at grain boundaries (GBs), leading to severe embrittlement. In this work, a multi-step thermomechanical process is employed to regulate discontinuous dynamic recrystallization (DDRX) and static recrystallization, achieving an ultrafine-grained microstructure. This optimized approach simultaneously impedes the continuous precipitation of the ordered L12 nanocrystals within the matrix and actively encourages the synergistic discontinuous precipitations of submicron L12 and Cr-rich σ particles at GBs, thereby enhancing (yield) strength and high-temperature thermal stability. The ultrafine grains facilitate uniform plastic deformation, characterized by pronounced parallel dislocation slip and stacking faults (SFs) within face-centered cubic (fcc) grains, while second-direction slips, SFs, and Lomer-Cottrell (L-C) lock networks near GB precipitates greatly alleviate stress concentration. Critically, the submicron L12 particles enveloping σ precipitates at GBs also display plastic deformation via mechanical twinning and dislocations, effectively impeding rapid crack propagation along GBs. This research not only provides new insights into the ductility-strength balance in advanced alloys but also proposes a compelling route for optimizing biphasic precipitation, expanding the applicability of high-Cr multicomponent alloys.沉淀强化是确保常规和多组分合金整体性能满足工业需求的关键策略。然而,高含铬合金的力学性能往往受到晶界处脆性富cr析出物的影响,导致严重的脆化。在这项工作中,采用多步骤的热机械过程来调节不连续动态再结晶(DDRX)和静态再结晶,获得超细晶组织。这种优化方法同时阻止了有序L12纳米晶体在基体内的连续析出,并积极促进亚微米L12和富cr σ颗粒在GBs处的协同不连续析出,从而提高了(屈服)强度和高温热稳定性。超细晶粒有利于均匀的塑性变形,其特征是面心立方(fcc)晶粒内存在明显的平行位错滑移和层错(SFs),而GB析出相附近的第二方向滑移、SFs和lmer - cottrell (L-C)锁网络极大地缓解了应力集中。重要的是,包裹σ相的亚微米L12颗粒也通过机械孪晶和位错表现出塑性变形,有效地阻碍了裂纹沿晶界的快速扩展。该研究不仅为先进合金的延性-强度平衡提供了新的见解,而且为优化双相析出,扩大高铬多组分合金的适用性提供了一条有吸引力的途径。Thin-Walled StructuresA data-driven enhanced generalized differential quadrature algorithm in free vibration analysis of shells of revolution with free-form meridian and their combined structuresQingyang Huang, Fenfei Hua, Qingquan You, Jie Gao, Xiaoqiang Zhoudoi:10.1016/j.tws.2024.111975 具有自由形式子午线的旋转壳及其组合结构自由振动分析中的数据驱动增强广义微分正交算法In this paper, a data-driven enhanced generalized differential quadrature (DE-GDQ) algorithm in free vibration analysis is proposed, which can be applied to shells of revolution with free-form meridian and their combined structures. According to first order shear deformation theory (FSDT) and Hamilton's principle, the governing equation for doubly-curved shells is obtained. The general boundary conditions are considered through artificial springs. Then the GDQ is introduced to solve the governing equations and the DE-GDQ is proposed on the basis of GDQ. After a detailed solution procedure of DE-GDQ is introduced and the convergence analysis is finished, multiple models and boundary conditions are validated including shells of revolution with conic section meridian, Haack series meridian, rational Bézier curve meridian. Isotropic materials and anisotropic materials including functionally graded (FG) materials are both verified. The free vibration analysis of combined structures is also finished and compared with finite element method (FEM). The comparison among DE-GDQ, GDQ and FEM shows that the DE-GDQ has greater advantages in terms of calculation efficiency, accuracy, and scope of application.提出了一种数据驱动的增强广义微分正交(DE-GDQ)自由振动分析算法,该算法可应用于具有自由形式子午线的旋转壳及其组合结构。根据一阶剪切变形理论(FSDT)和Hamilton原理,得到了双弯曲壳的控制方程。通过人工弹簧考虑一般边界条件。然后引入GDQ来求解控制方程,并在此基础上提出了DE-GDQ。介绍了DE-GDQ的详细求解过程,并进行了收敛性分析,验证了含圆锥截面子午线、Haack系列子午线、有理bsamizier曲线子午线的旋转壳的多种模型和边界条件。各向同性材料和各向异性材料包括功能梯度(FG)材料都进行了验证。对组合结构进行了自由振动分析,并与有限元法进行了比较。DE-GDQ与GDQ和FEM的比较表明,DE-GDQ在计算效率、精度和适用范围等方面具有更大的优势。来源:复合材料力学仿真Composites FEM

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