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【新文速递】2024年4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 2 篇,Mechanics of Materials 1 篇,International Journal of Plasticity 1 篇

International Journal of Solids and Structures

Effect of a subsurface void on the micromechanics of ductile metal indentation using remeshing

Debasree Das, Narayan K. Sundaram

doi:10.1016/j.ijsolstr.2024.112842

利用重网格法研究地下空洞对延性金属压痕微观力学的影响

Near-surface voids and pores are generated in metal processing operations as diverse as additive manufacturing and powder processing, but their effect on indentation hardness has not been explored outside homogenized frameworks. Here we model the micromechanics of near-surface void deformation up to closure in a wedge-indentation field in ductile metal, and reveal the considerable softening effect of voids on the indentation hardness. Both symmetrically and eccentrically located voids, at various depths below the free surface, are studied. Notably, the extent of apparent reduction in the elastic modulus due to a void is much smaller than its effect on apparent hardness, e.g. 6.5% against 55% for the same void. Critical to the simulations is an adaptive remeshing finite element (FE) framework that allows accurate capture of processes like void closure and void-wall self-contact. The simulations reveal the subsurface plastic strain, strain-rate, and velocity fields with high fidelity, and their radical differences from the radial indentation field in a void-free specimen. These differences include the presence of localized pockets of high and low strain, and the initial accommodation of material displaced by the indenter by a corresponding reduction in void area. Unlike voids under uniform compression, the void-area evolution in indentation shows a characteristic sigmoidal pattern of reduction with indentation depth for all but the smallest voids. Interestingly, the indented surface profile can exhibit a one-sided pile-up feature which is diagnostic of the presence of an eccentrically located sub-surface void. Our remeshing scheme is versatile, as exemplified by its ability to model the extreme deformation associated with two nearly closed-spaced voids under an indenter. Our work shows that void-closure simulations in related applications like forming could benefit from the adoption of a remeshing framework.

在增材制造和粉末加工等多种金属加工操作中都会产生近表面空洞和孔隙,但它们对压痕硬度的影响尚未在均质框架之外进行过探索。本文模拟了延性金属楔压痕场中近表面孔洞变形直至闭合的微观力学过程,揭示了孔洞对压痕硬度的显著软化作用。研究了自由表面以下不同深度的对称和偏心位置的空洞。值得注意的是,空穴对弹性模量的明显降低程度远远小于其对表观硬度的影响,例如,相同空穴对表观硬度的影响为6.5%对55%。模拟的关键是自适应网格有限元(FE)框架,该框架允许准确捕获空隙闭合和空隙壁自接触等过程。模拟结果显示了高逼真度的亚表面塑性应变场、应变速率场和速度场,以及它们与无空洞试样径向压痕场的根本差异。这些差异包括高应变和低应变的局部口袋的存在,以及通过相应的空隙面积减少,压头位移的材料的初始容纳。与均匀压缩条件下的孔洞不同,除最小孔洞外,压痕中孔洞面积随压痕深度的增加呈显著的s型变化。有趣的是,凹陷的表面轮廓可以表现出片面的堆积特征,这是对偏心位置的地下空洞存在的诊断。我们的网格重新划分方案是通用的,例如它能够模拟与压头下两个几乎封闭的空隙相关的极端变形。我们的工作表明,在成型等相关应用中的空隙闭合模拟可以从采用重网格框架中受益。


Journal of the Mechanics and Physics of Solids

Effective thermodynamic potentials and internal variables: Linear viscoelastic composites

Noel Lahellec, Renaud Masson, Pierre Suquet

doi:10.1016/j.jmps.2024.105649

有效热力学势和内部变量:线性粘弹性复合材料

New theoretical relations in linear viscoelasticity are derived by combining two different points of view. On the one hand, the general thermodynamic framework makes it possible to define the energy stored and the energy dissipated in linearly viscoelastic composites. On the other hand, the correspondence principle permits to express the macroscopic strain-stress relation as ordinary differential equations for a set of effective internal variables. A finite and small number of internal variables is rigorously sufficient in several cases of interest, including in particular particulate composites. Interpreting the macroscopic response as a rheological generalized Maxwell model allows us to compute the macroscopic free and dissipated energy of the composite. This interpretation is proved to be exact in several cases of interest. Coupled with Hashin–Shtrikman estimates, these thermodynamic functions provide additional information on the statistics of the field within each individual phase of the composite.

结合两种不同的观点,导出了线性粘弹性的新理论关系。一方面,一般的热力学框架使得可以定义线性粘弹性复合材料中储存的能量和耗散的能量。另一方面,对应原理允许将宏观应变-应力关系表示为一组有效内变量的常微分方程。有限和少量的内部变量在一些情况下是严格充分的,包括在特定的颗粒复合材料。将宏观响应解释为流变广义麦克斯韦模型使我们能够计算复合材料的宏观自由能和耗散能。这种解释在几个有趣的案例中被证明是准确的。结合Hashin-Shtrikman估计,这些热力学函数提供了复合材料每个单独相内的场统计信息的附加信息。


Quantifying the mechanical degradation of solid oxide cells based on 3D reconstructions of the real microstructure using a unified multiphysics coupling numerical framework

Yunpeng Su, Keda Ren, Zehua Pan, Jingyi Wang, Zheng Zhong, Zhenjun Jiao

doi:10.1016/j.jmps.2024.105654

使用统一的多物理场耦合数值框架,基于真实微观结构的三维重建来量化固体氧化物电池的力学退化

In this work, a multiphysics coupling numerical framework is developed to quantitatively investigate the initial performances of solid oxide cells (SOCs) based on the thermodynamically consistent integration of the finite element method (FEM) and the phase field method (PFM) to reveal the interaction between species-defect transport, electrochemical reaction kinetics, stress and mechanical damage in SOC electrodes. The modeling framework is validated by comparing the simulation results based on real 3D microstructure reconstructions of specific SOCs with the experimental measurements in electrolysis and fuel cell modes. The phenomena of internal microstructure fracture and delamination observed in the experiment thus can be numerically modeled to quantify the effects of thermal and chemical stresses on the mechanical degradation of heterogeneous electrodes. The framework is also applied in the cross-scale quantification of the possible mechanical damage in SOCs subjected to different mechanical boundary conditions. The framework proposed in this work is flexible, can be superimposed with other fields, and incorporates input from cross-scale simulations. It provides a great potential platform for the optimization of future energy devices considering actual operating conditions and fills the gap in theoretical multiphysics modeling in the field of SOCs.

在这项工作中,基于有限元法(FEM)和相场法(PFM)的热力学一致积分,开发了一个多物理场耦合数值框架来定量研究固体氧化物电池(SOC)的初始性能,以揭示SOC电极中物质缺陷传输、电化学反应动力学、应力和机械损伤之间的相互作用。通过将特定soc的真实三维微观结构重建的仿真结果与电解和燃料电池模式下的实验测量结果进行比较,验证了建模框架的有效性。因此,实验中观察到的内部微观结构断裂和分层现象可以通过数值模拟来量化热应力和化学应力对非均质电极机械降解的影响。该框架还应用于不同力学边界条件下soc可能发生的力学损伤的跨尺度量化。本工作提出的框架具有灵活性,可以与其他领域叠加,并包含来自跨尺度模拟的输入。它为考虑实际运行条件的未来能源器件的优化提供了一个极具潜力的平台,填补了soc领域理论多物理场建模的空白。


Mechanics of Materials

Identifying multiple synergistic factors on the susceptibility to stress relaxation cracking in variously heat-treated weldments

Yi Yang, Dong Han, Wei Zhang, Yanfei Gao, Jorge Penso, Zhili Feng

doi:10.1016/j.mechmat.2024.105013

确定了影响不同热处理焊件应力松弛开裂易感性的多种协同因素

The 347H austenitic stainless steel has been widely used for pressure vessels and pipeline (PVP) applications due to its excellent creep and corrosion resistance, which fit ideally to the harsh conditions in petrochemical industries, fossil fuel or nuclear power plants, and modern energy storages. However, a failure mode has been commonly observed with cracks emerging at the heat affected zone (HAZ) of weldments during post-weld heat treatment (PWHT) or under intermediate to high temperature service conditions. This phenomenon is termed as Stress Relaxation Cracking (SRC) since the purpose of PWHT is to relieve the welding-induced residual stress fields, or as Stress Age Cracking (SAC) if failure happens during service. A leading literature explanation of this failure suggests that the residual stress relaxation and the precipitation dissolution and/or re-precipitation occur in the same temperature range, which can lead to locally high strains and thus to crack at the grain boundaries. Since in situ spatial measurements of residual stress fields, microstructural evolution, and failure processes are nearly infeasible, this work recourses to a micromechanical finite element framework that models the high temperature failure as the nucleation and growth of grain boundary cavities, whereas various parameters such as thermomechanical loading history and its evolution, the competition of grain-interior dislocation creep and grain-boundary diffusion in failure lifetime, and microstructural heterogeneities (such as the precipitate free zone near grain boundaries) can be quantitatively incorporated. It can be concluded from these microstructure-explicit simulations that an accurate knowledge of residual stress evolution and a carefully calibrated set of material constitutive parameters are the essential prerequisites for lifetime predictions. The understanding of individual governing factors also leads to a mechanistic interpretation of the observed SRC susceptibility C-curves. These results suggest that the criticality of residual stress evolution, but not the precipitation-induced local strains, be the leading factor for SRC.

347H奥氏体不锈钢因其优异的抗蠕变和耐腐蚀性而广泛用于压力容器和管道(PVP)应用,非常适合石化工业,化石燃料或核电站以及现代能源储存的恶劣条件。然而,在焊后热处理(PWHT)或中高温使用条件下,焊接件的热影响区(HAZ)出现裂纹是一种常见的失效模式。这种现象被称为应力松弛开裂(SRC),因为PWHT的目的是消除焊接引起的残余应力场,或者在使用过程中发生失效时称为应力时效开裂(SAC)。对这种破坏的主要文献解释认为,残余应力松弛和析出溶解和/或再析出发生在同一温度范围内,这可能导致局部高应变,从而在晶界处开裂。由于对残余应力场、微观组织演变和破坏过程的原位空间测量几乎是不可实现的,因此本研究采用微力学有限元框架,将高温破坏模拟为晶界空腔的形核和生长,而各种参数,如热力学加载历史及其演变、晶粒内部位错蠕变和晶界扩散在破坏寿命中的竞争,显微组织的非均质性(如晶界附近的无析出带)可以定量地纳入。从这些微观结构模拟可以得出结论,残余应力演化的准确知识和精心校准的材料本构参数集是寿命预测的必要先决条件。对个体控制因素的理解也导致了对观察到的SRC敏感性c曲线的机制解释。这些结果表明,残余应力演化的临界性,而不是降水引起的局部应变,是导致SRC的主要因素。


International Journal of Plasticity

Tuning chemical short-range order for simultaneous strength and toughness enhancement in NiCoCr medium-entropy alloys

Siyao Shuang, Yanan Hu, Xiaotao Li, Fuping Yuan, Guozheng Kang, Huajian Gao, Xu Zhang

doi:10.1016/j.ijplas.2024.103980

调节NiCoCr中熵合金强度和韧性同时增强的化学短程顺序

The pursuit of enhancing strength and toughness remains a critical endeavor in the field of structural materials. This study explores two distinct strategies to overcome the traditional strength-toughness trade-off. Specifically, we manipulate the chemical composition and short-range order (SRO) of the NiCoCr medium-entropy alloy, which has shown remarkable fracture toughness in recent experiments. Utilizing molecular dynamics simulations, we uncover nano-scale deformation mechanisms during crack propagation. Our findings highlight that optimizing the SRO degree leads to improvements in both atomic scale strength and toughness defined as the area underneath stress-strain curves from MD simulations. In contrast, a trade-off between strength and toughness persists when only manipulating the Ni content in the NiCoCr alloy. Based on the simulation results, we establish a strong correlation between toughness, strength, surface energies, and unstable stacking fault energies. These factors are influenced by the chemical composition and SROs in NiCoCr, with SROs acting as strong obstacles to dislocations, thereby contributing to additional strength. The exceptional toughness of NiCoCr with SRO arises from a synergy of intrinsic and extrinsic mechanisms, including dislocation glide, nanobridging during nanovoid coalescence and zigzag crack path. It is found that, in the presence of SRO, intrinsic toughening mechanisms usually associated with crack tip blunting and dissipation can also facilitate the onset of extrinsic toughening mechanisms of nanobridging and zig-zag crack path associated with nanovoid formation and coalescence. This study emphasizes the importance of tailoring SRO in designing materials with enhanced strength and toughness.

提高材料的强度和韧性仍然是结构材料领域的一个重要课题。本研究探讨了两种不同的策略来克服传统的强度-韧性权衡。具体来说,我们在最近的实验中对NiCoCr中熵合金的化学成分和短程有序度(SRO)进行了控制,该合金在最近的实验中表现出了显著的断裂韧性。利用分子动力学模拟,我们揭示了裂纹扩展过程中的纳米级变形机制。我们的研究结果强调,优化SRO程度导致原子尺度强度和韧性的提高,原子尺度强度和韧性定义为MD模拟的应力-应变曲线下的区域。相反,当仅控制NiCoCr合金中的Ni含量时,强度和韧性之间的权衡仍然存在。基于模拟结果,我们建立了韧性、强度、表面能和不稳定层错能之间的强相关性。这些因素受到NiCoCr中的化学成分和sro的影响,sro作为位错的强大障碍,从而有助于增加强度。具有SRO的NiCoCr具有优异的韧性,这是由位错滑动、纳米空洞合并过程中的纳米桥接和锯齿裂纹路径等内在和外在机制共同作用的结果。研究发现,在SRO存在的情况下,通常与裂纹尖端钝化和耗散有关的内在增韧机制也可以促进与纳米孔洞形成和聚并有关的纳米桥接和锯齿形裂纹路径的外在增韧机制的发生。本研究强调了裁剪SRO在设计增强强度和韧性的材料中的重要性。



来源:复合材料力学仿真Composites FEM
MeshingACTMechanicalMaxwellAdditive断裂复合材料化学燃料电池通用增材焊接裂纹理论材料分子动力学控制焊件
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首次发布时间:2024-11-14
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【新文速递】2024年4月29日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 3 篇,Journal of the Mechanics and Physics of Solids 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 1 篇International Journal of Solids and StructuresA multiscale model to predict the equation of state of a saturated cement pasteY.S. Karinski, V.R. Feldgun, D.Z. Yankelevskydoi:10.1016/j.ijsolstr.2024.112851用多尺度模型预测饱和水泥浆体的状态方程An advanced multiscale analytical approach for predicting the Equation of State (EOS) of fully saturated cement pastes is presented. This approach models the matrix as an elastic–plastic material with linear hardening that includes capillary pores filled with water. The model takes into account both the stochastic variation of pore sizes and their spatial distribution. The microscale level is represented by a spherical medium having the mechanical properties of the cement paste matrix. A single spherical pore that is filled with compressible water is located at the center of the micro-domain. The behavior of the compressible water is modeled by the nonlinear Tait equation of state. The EOS at the macro level is obtained by averaging the micro level domain strains over the pore sizes and pore wall thicknesses. It is shown that the solution depends only on the ratio between the minimum pore wall thickness and the lower limit of capillary pore radius and is independent of each of these parameters separately. The EOS obtained by the proposed model shows good agreement with experimental data for cement paste with water/cement ratio w/c = 0.50. The performed parametric study shows that the bulk modulus and yield stress of undisturbed cement gel matrix significantly affect the EOS, while the variation of Poison ratio, plastic hardening parameter and minimum limit pore size and wall thickness (within physically accepted range) slightly affect the cement paste bulk behavior.提出了一种预测全饱和水泥浆体状态方程的先进多尺度分析方法。该方法将基体建模为具有线性硬化的弹塑性材料,其中包括充满水的毛细孔。该模型既考虑了孔隙大小的随机变化,又考虑了孔隙大小的空间分布。微尺度用具有水泥膏体基质力学性能的球形介质来表示。微畴的中心是一个充满可压缩水的球形孔。用非线性泰特状态方程来模拟可压缩水的行为。宏观上的EOS是通过对孔径和孔壁厚度上的微观域应变进行平均得到的。结果表明,溶液仅与最小孔壁厚度与毛细孔半径下限之比有关,与上述参数无关。对于水灰比w/c = 0.50的水泥浆体,模型得到的EOS与实验数据吻合较好。The performed parametric study shows that the bulk modulus and yield stress of undisturbed cement gel matrix significantly affect the EOS, while the variation of Poison ratio, plastic hardening parameter and minimum limit pore size and wall thickness (within physically accepted range) slightly affect the cement paste bulk behavior.Progressive failure analysis of z-pin reinforced composite pi jointsJames G. Finlay, Anthony M. Waas, Paul Davidson, Jonathan Bartley-Cho, Nav Muralirajdoi:10.1016/j.ijsolstr.2024.112849z销增强复合材料pi节点的递进破坏分析A finite element model of a z-pin reinforced composite pi joint has been developed and correlated against experimental results. A smeared cohesive zone modeling approach was implemented to represent the effect of z-pinning in an efficient and scalable manner. In the smeared approach, cohesive properties governing the traction-separation response of the z-pin reinforced areas were defined to account for the effective fracture toughness caused by z-pinning in an averaged sense. The crack band method was used to account for diffuse damage and failure in the weave of the pi preform. The damage in the preform developed due to delamination suppression caused by the z-pinning. The numerical model was calibrated using experimental data from pristine and defective z-pinned pi joints subjected to pull-off and side-bend loading. Comparisons of experimental and numerical results show good agreement in terms of structural response, critical loads, and failure modes.建立了z销增强复合材料pi节点的有限元模型,并与实验结果进行了对比。为了高效、可扩展地表示z轴固定的效果,实现了一种涂抹内聚区建模方法。在涂抹方法中,定义了控制z-pin增强区域的牵引-分离响应的内聚特性,以便在平均意义上解释z-pin引起的有效断裂韧性。采用裂纹带法对预制坯组织中的弥漫性损伤和破坏进行了分析。预成形中的损伤是由于z形钉钉抑制分层造成的。数值模型使用原始和有缺陷的z-钉pi关节在拉脱和侧弯载荷下的实验数据进行校准。实验结果与数值结果的比较表明,在结构响应、临界荷载和破坏模式方面,两者具有良好的一致性。Geometrically exact 3D beam theory with embedded strong discontinuities for modeling of localized failure in bendingSuljo Ljukovac, Adnan Ibrahimbegovic, Rosa-Adela Nava-Mejia, Ismar Imamovicdoi:10.1016/j.ijsolstr.2024.112850具有嵌入强不连续的几何精确三维梁理论用于弯曲局部破坏建模In this work, we propose the elastoplastic model of a three-dimensional (3D) geometrically exact beam, which can capture localized bending deformation leading to a plastic hinge. This is a follow-up work to Tojaga et al. (2023), where we only studied the fracture of fiber-like beam structures that break in mode I or mode II, here extended to handle beam-like behavior with bending failure and the main difficulty of the non-vectorial character of large 3D rotations. The Reissner model is chosen for representing the large elastic and large plastic deformations of such a beam model, which leads to the multiplicative decomposition of the rotation tensor. We shown how to replace this with the corresponding additive decomposition of the rotation vector derivatives, to be performed in the material description in the tangent space of SO(3) manifold in the initial configuration. The plasticity model for which we give a more detailed implementation employs a Rankin-like multi-surface plasticity criteria, where each moment vector component (i.e. torsion or bending) is considered separately. The non-local variational formulation is proposed to deal with the softening phenomena characteristic of localized bending failure, where the fracture energy is introduced as the main parameter for softening. The discrete approximation is built in terms of the embedded-discontinuity finite element method (ED-FEM), which introduces a jump in rotation vector that can be handled at the level of a particular beam element. This kind of approach builds upon the best approximation property of the FEM discrete approximation in the energy norm and provides the best-approximation property for the dissipated energy computations, and thus optimal computational accuracy if the quantity of interest is inelastic dissipation. The computations are carried out by the operator split method, which separates the computations of global state variables (displacements and moments) from local (plastic curvature) variables. Several illustrative examples are provided to confirm an excellent performance of the proposed methodology.在这项工作中,我们提出了三维(3D)几何精确梁的弹塑性模型,该模型可以捕获导致塑性铰链的局部弯曲变形。这是Tojaga等人(2023)的后续工作,我们只研究了在I型或II型模式下断裂的纤维状梁结构的断裂,这里扩展到处理弯曲破坏的类梁行为以及大3D旋转的非矢量特征的主要困难。选择Reissner模型来表示这种梁模型的大弹性和大塑性变形,从而导致旋转张量的乘法分解。我们展示了如何用相应的旋转矢量导数的加性分解来代替它,在初始构型的SO(3)流形的切空间中的材料描述中执行。我们给出更详细实现的塑性模型采用了类似rankin的多面塑性标准,其中每个矩矢量分量(即扭转或弯曲)被单独考虑。针对局部弯曲破坏的软化现象,提出了非局部变分公式,引入断裂能作为软化的主要参数。离散近似是根据嵌入不连续有限元法(ED-FEM)建立的,该方法引入了旋转矢量的跳跃,可以在特定梁单元的水平上处理。这种方法建立在能量范数中有限元离散近似的最佳近似性质之上,为耗散能量计算提供了最佳近似性质,从而在目标量为非弹性耗散时获得了最佳计算精度。计算采用算子分割法,将全局状态变量(位移和矩)的计算与局部状态变量(塑性曲率)的计算分离开来。给出了几个说明性的例子来证实所提出的方法的优良性能。Journal of the Mechanics and Physics of SolidsHeterostructured mechanical metamaterials inspired by the shell of Strombus gigasJuzheng Chen, Hao Wu, Jingzhuo Zhou, Ziyong Li, Ke Duan, Ruihan Xu, Tianyi Jiang, Hongyuan Jiang, Rong Fan, Roberto Ballarini, Yang Ludoi:10.1016/j.jmps.2024.105658受巨藻壳启发的异质结构机械超材料Despite being highly mineralized, the shells of molluscs exhibit superior strength and toughness because their architectural designs control the evolution of cracks and other types of localized deformation such as shear bands. The crossed-lamellar design of the shell of Strombus gigas, whose hierarchy consists of four distinct lamellar-shaped features assembled in a three-dimensional arrangement, represents the toughest of all seashells. A mechanical metamaterial that adapts the geometrical design of this queen conch is anticipated to circumvent the typical trade-offs between strength-ductility and strength-density. Inspired by the three-dimensional hierarchical and interactive architecture of the crossed-lamellar microstructure, we instruct the design of bio-inspired metamaterials that mitigate failure from the extension of a single shear band and instead develop numerous smaller bands confined within the individual plank-like zones introduced in their layered geometric design. The measured strength properties of these materials are found to increase in inverse proportion to the square root of the thickness of the layers in the hierarchy as a result of progressive deformation enabled by cross-layer interactions. The results provide a new perspective on the design of strong and tough mechanical metamaterials.尽管是高度矿化的,软体动物的壳表现出优越的强度和韧性,因为它们的结构设计控制了裂缝的演变和其他类型的局部变形,如剪切带。巨螺壳的交叉层状设计,其层次结构由四个不同的层状特征组成,它们以三维的方式排列,代表了所有贝壳中最坚硬的。一种机械超材料,适应这种皇后海螺的几何设计,有望规避典型的强度-延展性和强度-密度之间的权衡。受交叉层状微观结构的三维分层和交互结构的启发,我们指导了仿生超材料的设计,以减轻单个剪切带延伸造成的破坏,而不是在分层几何设计中引入的单个板状区域内发展许多较小的带。这些材料的测量强度特性被发现与层间相互作用导致的渐进变形成反比,与层次中各层厚度的平方根成反比。研究结果为强韧性机械超材料的设计提供了新的思路。International Journal of PlasticitySymmetry breaking induced asymmetric dislocation-planar fault interactions in ordered intermetallic alloysCheng Chen, Fei Xu, Jun Songdoi:10.1016/j.ijplas.2024.103982对称破缺引起有序金属间合金的不对称位错-平面断层相互作用In this study, we present the first comprehensive examination of symmetry breaking in the interactions between dislocation and superlattice planar faults, including anti-phase boundary (APB), complex stacking fault (CSF), superlattice intrinsic stacking fault (SISF), to reveal the underlying asymmetric dislocation reaction mechanisms depending on the sense of applied stress, employing both large-scale atomistic simulations and continuum dislocation theory. Four ordered intermetallic alloy systems including γ−Ni/γ′−Ni3Al and γ−Ni/γ′−Ni3Fe, γ−Al/γ−TiAl, and α−Ti/α2−Ti3Al were selected as the representative model systems, with two primary symmetry breaking effects, i.e., translational and three-fold rotational symmetry breaking considered. Detailed atomic steps of asymmetrical dislocation reactions and the corresponding asymmetrical dislocation bypassing mechanisms of precipitation have been elucidated, shown to be highly dependent on the geometrical configuration of the precipitate and the relative magnitudes of APB, CSF and SISF fault energies. A continuum model framework was then developed, which, for the first time, provides accurate and quantitative predictions of the threshold conditions triggering critical asymmetrical dislocation slips, verified to be in good agreement with the simulation results. Our study also successfully reproduced the experimentally observed dislocation-induced APB-SISF transformation, with a new dislocation reaction mechanism proposed to explain the transformation process. The findings are expected to be a key enabling stepstone for future innovation in intermetallic alloys strengthened through ordered phases for advanced applications in aeronautic and automotive industries.在这项研究中,我们首次采用大规模原子模拟和连续位错理论,对位错与超晶格平面断层(包括反相边界(APB)、复杂堆积断层(CSF)和超晶格本征堆积断层(SISF))之间相互作用的对称性破坏进行了全面研究,以揭示取决于外加应力的非对称位错反应机制。选取了γ-Ni/γ′-Ni3Al和γ-Ni/γ′-Ni3Fe、γ-Al/γ-TiAl和α-Ti/α2-Ti3Al等四个有序金属间合金体系作为代表性模型体系,考虑了两种主要的对称性破缺效应,即平移对称性破缺和三重旋转对称性破缺。阐明了非对称位错反应的详细原子步骤以及相应的非对称位错析出绕过机制,并证明其高度依赖于析出物的几何构型以及 APB、CSF 和 SISF 断裂能的相对大小。随后,我们建立了一个连续模型框架,首次对触发临界非对称位错滑移的阈值条件进行了精确的定量预测,经证实与模拟结果十分吻合。我们的研究还成功再现了实验观察到的位错诱发 APB-SISF 转变,并提出了一种新的位错反应机制来解释转变过程。这些发现有望成为未来金属间合金创新的重要基石,通过有序相强化金属间合金,使其在航空和汽车工业中得到先进应用。Thin-Walled StructuresTemperature influence on the natural and forced vibrations of laminate plates with fractional Zener viscoelastic layersPrzemysław Litewka, Roman Lewandowskidoi:10.1016/j.tws.2024.111943温度对分数齐纳粘弹性层合板自然振动和强迫振动的影响The paper is devoted to the analysis of the influence of ambient temperature on the linear free and non-linear harmonic vibrations of laminate plates with viscoelastic layers. The Zener fractional material model is adopted. The plate kinematics is described using the refined zig-zag theory. The formulation of vibrations of the plate is based on the physical law with the separation of deviatoric and volumetric deformation. The temperature influence is included using the frequency-temperature superposition principle. The shift factor applied to modify the damping properties of the viscoelastic material is computed using the Willams-Landel-Ferry formula.The paper contains the results of several analyses of laminate plates with various viscoelastic materials for which the material data were available in the literature. In particular, the analyses focus on determination of the properties characteristic for the plates with Zener fractional model under the influence of the ambient temperature.本文研究了环境温度对粘弹性层合板线性自由振动和非线性谐波振动的影响。采用齐纳分式材料模型。板的运动学用精细的锯齿形理论来描述。板的振动公式是基于物理定律,分离了偏变形和体积变形。利用频率-温度叠加原理考虑了温度的影响。采用williams - landel - ferry公式计算了用于改变粘弹性材料阻尼特性的位移因子。本文包含了几种不同粘弹性材料层压板的分析结果,这些材料数据在文献中是可用的。重点分析了齐纳分数阶模型板在环境温度影响下的性能特性。来源:复合材料力学仿真Composites FEM

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