【新文速递】2024年3月17日固体力学SCI期刊最新文章

 

今日更新：International Journal of Solids and Structures 6 篇，Journal of the Mechanics and Physics of Solids 1 篇，Mechanics of Materials 1 篇，International Journal of Plasticity 4 篇，Thin-Walled Structures 1 篇

International Journal of Solids and Structures

Decoding the origins of strength anisotropy in two-dimensional materials

Guoqiang Zhang, Siyu Liu, Huasong Qin, Yilun Liu

doi:10.1016/j.ijsolstr.2024.112762

解密二维材料强度各向异性的起源

Defects are inevitable in two-dimensional (2D) materials, which is widely recognized to affect the strength of 2D materials. It is known the uniaxial tension strength is significantly different along different directions of defective 2D materials. The defect induced strength anisotropy should have equal importance to defect strength, but unfortunately the mechanism and quantitative description of defect induced anisotropic strength are still unknown. In principle, the atomic origin of materials failure can be attributed to bond fracture, especially for 2D materials comprised of covalent bonds. From the viewpoint of bond fracture, the mystery of anisotropic strength of defective 2D materials is explored, that strength-orientation relations are consisted of complex multi-curves and each curve corresponds to the fracture of same bond. By considering the balance between bond stretch resulting from external loading and bond strength, a strength theory is developed, which can describe the anisotropic strength of graphene and h-BN with vast types of defects, like grain boundary, void, crack. This work deepens the understanding of defect induced anisotropic mechanical properties in 2D materials, which may facilitate defect engineering in 2D materials.

二维（2D）材料中不可避免地存在缺陷，这已被广泛认为会影响二维材料的强度。众所周知，缺陷二维材料的单轴拉伸强度沿不同方向存在显著差异。缺陷诱导的强度各向异性应与缺陷强度具有同等重要性，但遗憾的是，缺陷诱导的各向异性强度的机理和定量描述仍然未知。原则上，材料失效的原子起源可归结为键断裂，尤其是由共价键组成的二维材料。从键断裂的观点出发，探索了缺陷二维材料各向异性强度的奥秘，即强度-方向关系由复杂的多曲线组成，每条曲线对应于同一键的断裂。通过考虑外部载荷导致的键拉伸与键强度之间的平衡，建立了一种强度理论，它可以描述具有晶界、空隙、裂纹等多种缺陷的石墨烯和 h-BN 的各向异性强度。这项工作加深了人们对二维材料中缺陷诱导的各向异性力学性能的理解，有助于二维材料中的缺陷工程。

Contact mechanics of open-cell foams with macroscopic asperities

A. Wilkinson, J.-P. Crété, S. Job, M. Rachik, N. Dauchez

doi:10.1016/j.ijsolstr.2024.112769

具有宏观微孔的开孔泡沫的接触力学

Poroelastic materials mounted against rigid surfaces often result in partial contact between the two, affecting their mechanical interaction. The surface roughness of cellular materials introduces complexity in predicting their behavior due to the interface with partial contact. This interface exhibits a stiffness distinct from the bulk material, which is driven by the surface asperities and the preload. This study conducts compression experiments on an open-cell poroelastic melamine foam, and compares them to finite elements simulations and analytic predictions. The material’s intrinsic stress–strain nonlinearity is accounted for, and an original hyperelastic aging model is proposed to achieve accurate predictions of its compression stiffness across multiple time scales. Predicting the compression stiffness of a macroscopic pyramidal asperity demonstrates a good agreement with the simple analytic solution for an elastic pyramidal geometry. Using a Greenwood–Williamson-like model based on the distribution of asperities of different heights, we propose a method to predict the contact stiffness of a rough surface. Our findings have important implications for understanding and optimizing efficient vibration barriers, resulting from the simple stacking of layers and screens of raw poroelastic materials, a configuration widely adopted in the transportation and civil engineering industries.

安装在刚性表面上的多孔弹性材料通常会导致两者部分接触，从而影响它们的机械相互作用。由于部分接触的界面，蜂窝材料的表面粗糙度给预测其行为带来了复杂性。这种界面表现出的刚度不同于块状材料，它是由表面粗糙度和预紧力驱动的。本研究对开孔多孔弹性三聚氰胺泡沫进行了压缩实验，并将其与有限元模拟和分析预测进行了比较。研究考虑了材料固有的应力-应变非线性特性，并提出了一个独创的超弹性老化模型，以实现对材料在多个时间尺度上的压缩刚度的精确预测。对宏观金字塔尖面压缩刚度的预测结果表明，与弹性金字塔几何形状的简单解析解十分吻合。利用基于不同高度的表面粗糙度分布的格林伍德-威廉森（Greenwood-Williamson-like）模型，我们提出了一种预测粗糙表面接触刚度的方法。我们的发现对于理解和优化高效振动屏障具有重要意义，这种屏障是由原始孔弹性材料的层和筛简单堆叠而成，是交通和土木工程行业广泛采用的一种配置。

A Hybrid Discrete-Finite Element model for continuous and discontinuous beam-like members including nonlinear geometric and material effects

Igor Bouckaert, Michele Godio, João Pacheco de Almeida

doi:10.1016/j.ijsolstr.2024.112770

包含非线性几何和材料效应的连续和不连续梁状构件的离散-有限元混合模型

This paper introduces a novel formulation, called Hybrid Discrete-Finite Element (HybriDFEM) method, for modeling one-directional continuous and discontinuous planar beam-like members, including nonlinear geometric and material effects. In this method, the structure is modeled as a series of distinct rigid blocks, connected to each other through contact pairs distributed along the interfaces. Each of those contact pairs are composed of two nonlinear multidirectional springs in series, which can represent either the deformation of the blocks themselves, or the deformation of their interface. Unlike the Applied Element Method, in which contact pairs are composed of one single spring, the current approach allows capturing phenomena such as sectional deformations or relative deformations between two blocks composed of different materials. This method shares similarities with the Discrete Element Methods in its ability to model contact interfaces between rigid or deformable units, but does not require a numerical time-domain integration scheme. More importantly, its formulation resembles that of the classical Finite Elements Method, allowing one to easily couple the latter with HybriDFEM. Following the presentation of its formulation, the method is benchmarked against analytical solutions selected from the literature, ranging from the linear-elastic response of a cantilever beam to the buckling and rocking response of continuous flexible columns, and rigid block stackings. One final example showcases the coupling of a HybriDFEM element with a linear beam finite element.

本文介绍了一种称为混合离散-有限元（HybriDFEM）方法的新公式，用于模拟单向连续和不连续平面梁状构件，包括非线性几何和材料效应。在该方法中，结构被建模为一系列不同的刚性块，通过沿界面分布的接触对相互连接。每个接触对都由两个串联的非线性多向弹簧组成，它们既可以代表块本身的变形，也可以代表其界面的变形。与由单个弹簧组成接触对的应用元素法不同，目前的方法可以捕捉截面变形或由不同材料组成的两个体块之间的相对变形等现象。这种方法与离散元素方法相似，都能模拟刚性或可变形单元之间的接触界面，但不需要时域数值积分方案。更重要的是，该方法的表述与经典有限元法相似，因此可以轻松地将后者与 HybriDFEM 结合起来。在介绍了该方法的表述之后，我们从文献中选取了一些分析解决方案对其进行了基准测试，这些解决方案包括悬臂梁的线弹性响应、连续柔性柱的屈曲和摇摆响应以及刚性块堆叠。最后一个例子展示了 HybriDFEM 元素与线性梁有限元的耦合。

An in-plane phase-field ductile fracture model for orthotropic paperboard material

Alessandro Marengo, Umberto Perego, Eric Borgqvist, Johan Tryding, Matti Ristinmaa

doi:10.1016/j.ijsolstr.2024.112763

正交各向同性纸板材料的面内相场韧性断裂模型

A phase-field ductile fracture formulation for orthotropic paperboard materials is proposed, based on an anisotropic, multi-surface elastoplastic model describing the in-plane behavior of paperboard. A variational statement for the finite-step elastoplastic problem is extended to include the variational description of Griffith-type brittle fracture by a phase-field gradient term. The interaction between plastic and fracture dissipation mechanisms is modeled by introducing a scalar modulation function, assuming plasticity driven damage growth. This function depends on a scalar measure of the plastic strain components in the material orthotropy frame. It modifies the fracture activation criterion in a non-variational fashion, resulting in a direction-dependent material strength against crack propagation. The model performance is assessed by comparing numerical simulations and experimental tests conducted in a climate-controlled laboratory.

根据描述纸板平面内行为的各向异性多面弹塑性模型，提出了正交纸板材料的相场韧性断裂公式。对有限步弹塑性问题的变分说明进行了扩展，以包括通过相场梯度项对格里菲斯型脆性断裂的变分描述。塑性和断裂耗散机制之间的相互作用是通过引入标量调制函数来建模的，假定塑性驱动损伤增长。该函数取决于材料正交框架中塑性应变分量的标量。它以非变量方式修改了断裂激活准则，从而产生了与裂纹扩展方向相关的材料强度。通过比较数值模拟和在气候控制实验室进行的实验测试，对模型性能进行了评估。

Peeling pressure-sensitive adhesive elastica from elastica with pinned and roller ends

Raymond H. Plaut

doi:10.1016/j.ijsolstr.2024.112764

将压敏胶弹性体与带销钉和滚轴的弹性体剥离

Quasi-static peeling of a horizontal elastica (the tape) from another horizontal elastica (the beam) supported by a pinned end and a roller end is analyzed. Bending resistance is assumed to dominate the behavior, and large deflections and rotations are allowed. The tape is shorter than the beam and is pulled upward at a constant angle with the horizontal. A transversality (debonding) condition is derived for peeling, based on the common fracture mechanics approach. Displacement control is considered. The associated force exhibits its peak value at the onset of peeling. The vertical deflection of the pulled end of the tape also is of interest, especially when the tape detaches from the beam. Equilibrium curves are determined, and the effects of the following parameters on the peak force and the detachment deflection are investigated: the relative thicknesses and moduli of elasticity of the tape and the beam; the relative lengths of the tape and the beam; the angle of pulling; and the nondimensional work of adhesion. The system may be used as a model of peeling bandages, medical patches, biosensors, and other wearable devices from skin. Other possible thin flexible substrates include fabric, paper, leather, rubber, and plastics.seen.

分析了由销端和辊端支撑的水平弹性体（胶带）与另一水平弹性体（梁）之间的准静态剥离。假定弯曲阻力在行为中占主导地位，并允许较大的挠度和旋转。胶带比横梁短，以与水平面成恒定角度向上拉。根据常见的断裂力学方法，得出了剥离的横向（脱粘）条件。考虑了位移控制。相关力在剥离开始时达到峰值。胶带受拉端垂直方向的挠度也很重要，尤其是当胶带从梁上脱落时。我们确定了平衡曲线，并研究了以下参数对峰值力和脱离挠度的影响：胶带和横梁的相对厚度和弹性模量；胶带和横梁的相对长度；拉伸角度；以及粘附的非尺寸功。该系统可用作从皮肤上剥离绷带、医用贴片、生物传感器和其他可穿戴设备的模型。其他可能的薄柔性基材包括织物、纸张、皮革、橡胶和塑料。

Prediction of temperature dependent effective moduli of metal particle composites with debonding damage

Xuyao Zhang, Xianhe Zhang, Pan Dong, Jianzuo Ma, Ruzhuan Wang, Weiguo Li

doi:10.1016/j.ijsolstr.2024.112775

具有脱粘损伤的金属颗粒复合材料随温度变化的有效模量预测

Debonding is one of the most commonly observed damage mechanisms in metal particle composites, which poses additional difficulties for material characterization and performance evaluation. In this paper, the equivalent modulus of debonded particles in tension and compression was derived in accordance with the debonding configurations, respectively. The debonded particles were then incorporated into the Mori-Tanaka method as a third phase with reduced modulus but perfectly bonded to the matrix. Finally, a micromechanical model of the temperature dependent effective moduli of metal particle composites was proposed, taking into account the degradation of the matrix modulus and the evolution of percentage of debonded particles at elevated temperatures. The model predictions were in high agreement with the experimental and simulation results, demonstrating the predictive ability of the micromechanical model. This study gives a highly practical forecasting toolkit for composite modulus evaluation over a wide temperature range. In addition, parametric analyses were carried out to investigate the effects of debonding configuration, temperature, and percentage of debonded particles, which contributes to further understanding of the debonding mechanism, leading to rational material design.

脱粘是金属颗粒复合材料中最常见的损伤机制之一，这给材料表征和性能评估带来了更多困难。本文根据脱粘构型分别推导出了脱粘颗粒在拉伸和压缩状态下的等效模量。然后将脱粘颗粒作为模量降低但与基体完美结合的第三相纳入 Mori-Tanaka 方法。最后，考虑到基体模量的退化和高温下脱胶颗粒百分比的变化，提出了金属颗粒复合材料有效模量随温度变化的微观力学模型。模型预测结果与实验和模拟结果高度一致，证明了微机械模型的预测能力。这项研究为宽温度范围内的复合材料模量评估提供了一个非常实用的预测工具包。此外，还进行了参数分析，研究了脱粘构型、温度和脱粘颗粒百分比的影响，这有助于进一步了解脱粘机理，从而进行合理的材料设计。

Journal of the Mechanics and Physics of Solids

Curvature controls beading in soft coated elastic cylinders: Finite wavemode instability and localized modulations

Matteo Taffetani, Matthew G. Hennessy

doi:10.1016/j.jmps.2024.105606

曲率控制软涂层弹性圆柱体中的串珠：有限波模不稳定性和局部调制

Axisymmetric beading instabilities in soft, elongated cylinders have been observed in a plethora of scenarios, ranging from cellular nanotunnels and nerves in biology to swollen cylinders and electrospun fibers in polymer physics. One of the common geometrical features that can be seen in these systems is the finite wavelength of the emerging pattern. However, modelling studies often predict that the instability has an infinite wavelength, which can be associated with localized necking or bulging. In this paper, we consider a soft elastic cylinder with a thin coating that resists bending, as described by the Helfrich free energy functional. The bending stiffness and natural mean curvature of the coating are two novel features whose competition against bulk elasticity and capillarity is investigated. For intermediate values of the bending stiffness, a linear stability analysis reveals that the mismatch between the current and natural mean curvature of the coating can lead to patterns emerging with a finite wavelength. This analysis creates a continuous bridge between the classical solutions of the shape equation obtained from the Helfrich functional and a curvature-controlled zero-wavemode instability, similar to the one induced by the competition between bulk elasticity and capillarity. The weakly non-linear analysis predicts that the criticality of the bifurcation depends on the controlling parameter, with both supercritical and subcritical bifurcations possible. When capillarity is introduced, the criticality of the bifurcation changes in a non-trivial way.

从生物学中的细胞纳米隧道和神经，到高分子物理学中的膨胀圆柱体和电纺纤维，人们在许多情况下都观察到了柔软细长圆柱体中的轴对称串珠状不稳定性。在这些系统中可以看到的共同几何特征之一是新出现图案的有限波长。然而，建模研究通常预测不稳定性具有无限波长，这可能与局部缩颈或隆起有关。在本文中，我们考虑了一个带有薄涂层的软弹性圆柱体，它可以抵抗弯曲，正如赫尔弗里希自由能函数所描述的那样。涂层的弯曲刚度和自然平均曲率是两个新特征，本文研究了这两个特征与块体弹性和毛细管性之间的竞争关系。对于弯曲刚度的中间值，线性稳定性分析表明，涂层的电流和自然平均曲率之间的不匹配会导致出现有限波长的图案。该分析在由赫尔弗里希函数得到的形状方程经典解与曲率控制的零波模不稳定性之间建立了一座连续的桥梁，零波模不稳定性类似于体弹性与毛细管之间的竞争所引起的不稳定性。弱非线性分析预测，分岔的临界程度取决于控制参数，超临界和亚临界分岔都有可能发生。当引入毛细现象时，分岔的临界性会发生非同一般的变化。

Mechanics of Materials

Threshold and structure of HCP/FCC nucleation in BCC iron under arbitrary triaxial compression: Atomistic simulations

Xiu-Xia Guo, Dong-Dong Jiang, Jian-Li Shao

doi:10.1016/j.mechmat.2024.104977

任意三轴压缩下 BCC 铁中 HCP/FCC 成核的阈值和结构：原子模拟

Shear deformation is considered one of the primary factors determining the threshold of structural transition (ST). It is important to quantitatively express the relationship between shear deformation and the ST threshold for the in-depth development of ST dynamics models. This work used classical molecular dynamics methods to study the effect of shear deformation on the ST in iron by controlling the triaxial ratio of compression. Based on the simulation results, there are significant differences in the microstructure for different loading paths. HCP lamellar twins, HCP-FCC thin twins, and crossed HCP twins embedded with parallel hexahedral FCC grains are all observed, as uniaxial loading transitions to equiaxial loading. The changes in pressure and the softening range of shear stress under different triaxial compressions are revealed. By introducing the strain triaxiality (taking the ratio of shear strain to volumetric strain), a general expression of the pressure threshold of ST under high strain rate compression-shear was proposed. In addition, whether the close-packed plane is prone to phase transition under different strain environments is explained based on the results of stacking fault energy.

剪切变形被认为是决定结构转换（ST）阈值的主要因素之一。定量表达剪切变形与结构转变阈值之间的关系对于深入开发结构转变动力学模型非常重要。本研究采用经典分子动力学方法，通过控制三轴压缩比来研究剪切变形对铁中 ST 的影响。根据模拟结果，不同加载路径下的微观结构存在显著差异。当单轴加载过渡到等轴加载时，都会观察到 HCP 片状孪晶、HCP-FCC 薄孪晶以及嵌入平行六面体 FCC 晶粒的交叉 HCP 双胞胎。揭示了不同三轴压缩下压力和剪应力软化范围的变化。通过引入应变三轴性（取剪切应变与体积应变之比），提出了高应变率压缩剪切下 ST 压力阈值的一般表达式。此外，基于堆积断层能的结果，解释了在不同应变环境下紧密堆积平面是否容易发生相变。

International Journal of Plasticity

Atomic-scale observation and characterization of deformation twins in uniaxial tensile-deformed 120Mn13 steel

Zhimin Ding, Linnan Dong, Neng Fu, Jiaoyang Sun, Yongchang Bao

doi:10.1016/j.ijplas.2024.103943

单轴拉伸变形 120Mn13 钢中变形孪晶的原子尺度观测与表征

High-resolution transmission electron microscope was used to observe and characterize the different formation stages of zero-strain twins in uniaxial tensile-deformed 120Mn13 steel at the atomic scale, which revealed the growth process of zero-strain twins in coarse-grained austenitic manganese steels. Here, plenty of zero-strain twins are observed in deformed 120Mn13 steel and they can be formed by three types of precursors. Their processes of expansion and connection, thickening and thinning can be carried out through the transformation of 9R phase with the matrix and the twin. A new 9R phase with different stacking sequences is firstly discovered and defined as 9R-Ⅱ to distinguish it from the classical 9R phase (9R-Ⅰ). 9R-Ⅰ and 9R-Ⅱ have the same lattice structure but different internal atomic arrangements and satisfy a twin-like relationship. In addition, a new formation mechanism of zero-strain twins based on the 9R phase transformation is proposed.

利用高分辨率透射电子显微镜在原子尺度上观察和表征了单轴拉伸变形 120Mn13 钢中零应变孪晶的不同形成阶段，揭示了粗晶粒奥氏体锰钢中零应变孪晶的生长过程。在这里，我们在变形 120Mn13 钢中观察到大量零应变孪晶，它们可由三种类型的前驱体形成。它们的膨胀和连接、增厚和减薄过程可以通过 9R 相与基体和孪生体的转化来实现。为了与经典的 9R 相（9R-Ⅰ）区分开来，我们首先发现了一种具有不同堆积序列的新 9R 相，并将其定义为 9R-Ⅱ。9R-Ⅰ 和 9R-Ⅱ 具有相同的晶格结构，但内部原子排列方式不同，具有孪生关系。此外，还提出了一种基于 9R 相变的零应变孪晶形成新机制。

Superior strength-ductility synergy of Mg-Nd-Zn-Zr alloy rod achieved by drawing at elevated temperatures

Baoxue Zhou, Xiang Wang, Jimiao Jiang, Chun Chen, Xiyuan Zhang, Jialin Niu, Jia Pei, Hua Huang, Deli Wang, Guangyin Yuan

doi:10.1016/j.ijplas.2024.103944

通过高温拉拔实现 Mg-Nd-Zn-Zr 合金棒材卓越的强度-电导率协同效应

Mg alloys with superior strength-ductility synergy is highly desired for applications. In this study, the as-extruded Mg-Nd-Zn-Zr (JDBM) alloy rod was subjected to single-pass drawing over a range of temperature 200 ∼ 600°C to enhance the properties. After drawing, a more homogeneous and refined microstructure developed because of dynamic recrystallization (DRX) and dynamic precipitation (DP). With the increase of drawing temperature, grain sizes increased first and then decreased due to the competition of grain nucleation and growth, while the sizes of the secondary phase particles varied in the same way. And a nearly basal texture evolved from a rare earth texture of the as-extruded sample. The yield strength of the as-drawn samples increased by ∼2.2 times with a sacrifice of elongation to fracture at different level. The high yield strength mainly originated from grain boundary and dislocation strengthening. An optimal combination of high yield strength (∼301 MPa) and good ductility (elongation to fracture of ∼19% and improved strain hardening capacity) was obtained after drawing at 500°C. The yield strength enhancement was mainly derived from texture and dislocation strengthening. Grain and secondary phase particle refinement, large volume fraction of low angle grain boundaries and reduced geometrically necessary dislocations are considered to be beneficial to the good ductility. In addition, a novel method has been proposed to fabricate materials with superior strength-ductility synergy by deformation with large strain at high temperatures to activate severe DP.

镁合金具有卓越的强度-电导率协同作用，在应用中备受青睐。在本研究中，为了提高性能，对挤压成型的 Mg-Nd-Zn-Zr (JDBM) 合金棒材在 200 ∼ 600°C 的温度范围内进行了单程拉拔。拉拔后，由于动态再结晶（DRX）和动态沉淀（DP）的作用，显微组织更加均匀和细化。随着拉拔温度的升高，由于晶粒成核和生长的竞争，晶粒大小先增大后减小，而次相颗粒的大小也以同样的方式变化。从挤压样品的稀土质地演变出近乎基底的质地。拉拔样品的屈服强度提高了 2.2 倍，但不同程度地牺牲了断裂伸长率。高屈服强度主要来源于晶界和位错强化。在 500°C 下拉拔后，获得了高屈服强度（∼301 MPa）和良好延展性（断裂伸长率∼19%，应变硬化能力提高）的最佳组合。屈服强度的提高主要源于质地和位错的强化。晶粒和次生相颗粒细化、低角度晶界体积分数大以及几何必要位错减少被认为有利于获得良好的延展性。此外，还提出了一种新方法，即通过高温下的大应变变形来激活严重的位错，从而制造出具有卓越强度-韧性协同作用的材料。

Multi-scale damage mechanism of hierarchically structured high-strength martensitic steels under shock loading

Zhaoguo Zhang, Sen Chen, Yifei Hong, Xuhai Li, Jian Zhang, Yong Xiao, Guoqiang Luo, Yuying Yu, Jianbo Hu

doi:10.1016/j.ijplas.2024.103945

冲击加载下分层结构高强度马氏体钢的多尺度损伤机理

The multi-scale damage behaviors and underlying mechanisms of hierarchically structured high-strength martensitic steels are investigated via plate-impact recovery experiments, postmortem characterizations. Plate-impact experiments were conducted at compressive peak stresses ranging from approximately 5.5 to 11.0 GPa, and the tensile strain rates are ∼105 s−1. Significant improvement in the spall strength of the heat-treated martensitic steel is achieved (5.4 GPa), about 80% higher compared to the as-received bainite steel. The spall failure of the investigated martensitic steel exhibited a mixed-mode combination of brittle (micro-cracks) and ductile (voids) characteristics, known as quasi-cleavage spallation. As the impact velocity increased, voids nucleated successively at different types of boundaries as follows: boundaries between enriched zone and depleted zones, prior austenite grain boundaries, packet boundaries, block boundaries and lath boundaries. Shear cracking was found to be an important mechanism to accommodate the severe plastic deformation during spallation, giving the strict geometric constraints due to void nucleation occurring tend at grain boundaries. Additionally, molecular dynamics simulations considering realistic hierarchical structure of Martensitic steel have been developed to validate the experimental results. These findings and simulation methods contribute a better understanding of the spall behavior of martensitic steels, as well as guidance for future design of high-strength martensitic steels with exceptional reliability and safety under extreme conditions.

通过平板冲击恢复实验和死后表征，研究了分层结构高强度马氏体钢的多尺度损伤行为和内在机制。平板冲击实验在约 5.5 至 11.0 GPa 的压缩峰值应力范围内进行，拉伸应变速率为 ∼105 s-1。热处理马氏体钢的抗剥落强度显著提高（5.4 GPa），与未加工贝氏体钢相比提高了约 80%。所研究的马氏体钢的剥落破坏表现出脆性（微裂纹）和韧性（空洞）的混合模式，即准脆性剥落。随着冲击速度的增加，空隙相继在以下不同类型的边界处成核：富集区和贫化区之间的边界、奥氏体晶粒前边界、封包边界、块状边界和板条边界。由于空洞成核往往发生在晶界处，因此在严格的几何约束条件下，剪切开裂被认为是适应剥落过程中严重塑性变形的重要机制。此外，考虑到马氏体钢的现实层次结构，还开发了分子动力学模拟来验证实验结果。这些发现和模拟方法有助于更好地理解马氏体钢的剥落行为，并为未来设计在极端条件下具有卓越可靠性和安全性的高强度马氏体钢提供指导。

Deformation mechanisms in the α phase of the Ti-6Al-2Sn-4Zr-2Mo titanium alloy: in situ experiments and simulations

S. Hémery, A. Naït-Ali, O. Smerdova, C. Tromas

doi:10.1016/j.ijplas.2024.103947

Ti-6Al-2Sn-4Zr-2Mo 钛合金 α 相的变形机制：现场实验与模拟

Titanium alloys are widely employed in aerospace applications due to an outstanding combination of properties. The variety of loading conditions and microstructures encountered in industrial components is urging the development of microstructure sensitive modeling capabilities. In particular, reliable predictions require a good knowledge of operating deformation mechanisms. The present study aims at providing a thorough characterization of deformation mechanisms in the near-α Ti-6Al-2Sn-4Zr-2Mo alloy using experiments and simulations. The sequential activation of deformation mechanisms in the α phase was monitored in situ during a tensile test carried out in a scanning electron microscope using a combination of slip traces analysis and electron back-scattered diffraction. Basal slip is activated first, and prismatic slip activity, which proceeds at a higher macroscopic stress level, is needed for a significant creep/relaxation to occur. While little evidence of < a> -type pyramidal slip was found, < c+a> pyramidal slip involved first-order pyramidal planes and operates at stress levels near or above the 0.2% proof stress. Atomic force microscopy characterization of the features of the different slip modes revealed that < a> slip is coarser and wavier than < c+a> slip. Twinning, which is usually neglected in such alloys within this strain regime, was observed to be slip stimulated at a plastic strain as low as 0.5 %. Crystal plasticity parameters leading to an accurate simulation of the activation sequence of deformation mechanisms were then determined. For this purpose, critical resolved shear stress values were derived for the different slip and twinning modes using specific approaches and subsequently validated using crystal plasticity simulations based on fast-Fourier transforms.

钛合金因其出色的综合性能而被广泛应用于航空航天领域。工业部件中的加载条件和微观结构多种多样，因此需要开发对微观结构敏感的建模能力。特别是，可靠的预测需要充分了解工作变形机制。本研究旨在利用实验和模拟对近α Ti-6Al-2Sn-4Zr-2Mo 合金的变形机制进行全面描述。在扫描电子显微镜下进行拉伸试验时，结合滑移痕迹分析和电子反向散射衍射，对 α 相中变形机制的顺序激活进行了现场监测。基底滑移首先被激活，棱柱滑移活动在更高的宏观应力水平下进行，需要显著的蠕变/松弛才能发生。虽然几乎没有发现 < a> 型金字塔滑移的证据，但 < c+a> 金字塔滑移涉及一阶金字塔平面，并在接近或高于 0.2% 证明应力的应力水平下运行。对不同滑移模式特征的原子力显微镜分析表明，< a>滑移比< c+a>滑移更粗更细。在这种应变机制下，此类合金中通常被忽视的孪晶现象在塑性应变低至 0.5 % 时也会受到滑移刺 激。随后确定了晶体塑性参数，从而准确模拟了变形机制的激活顺序。为此，使用特定方法得出了不同滑移和孪晶模式的临界分辨剪应力值，随后使用基于快速傅立叶变换的晶体塑性模拟进行了验证。

Thin-Walled Structures

Research on lateral buckling of eccentrically compressed H-shaped section aluminum alloy perforated members

Wenyuan Kong, Liang Zhou, Hang Yang, Zhiqiang Huang, Wei Chen, Yu Chen

doi:10.1016/j.tws.2024.111804

偏心压缩 H 型截面铝合金穿孔构件的侧向屈曲研究

Aluminum alloy members are widely used in various engineering fields because of the light weight and corrosion resistance. However, the existing research on the stability of the aluminum alloy beam-column with web openings is insufficient. This study carried out the eccentrically compressed tests for 60 H-shaped section aluminum alloy perforated members, taking the opening number, opening diameter, slenderness ratio, and eccentricity distance around major axis as main variables. The tested specimens showed obvious lateral buckling. The effects of web openings on buckling mode, stability bearing capacity, longitudinal deformation, lateral deformation, and strain development of the member are studied. The influence of each variable on the mechanical properties is studied, which provides the basis for design of the structure members. Several main parameters are analyzed in depth using verified finite element model. Based on the results of test and FEA, the design method for lateral stability bearing capacity of H-shaped section aluminum alloy perforated members is proposed with reference to existing specifications.

铝合金构件因重量轻、耐腐蚀而被广泛应用于各种工程领域。然而，现有关于带腹板开孔铝合金梁柱稳定性的研究并不充分。本研究以开孔数量、开孔直径、细长比和主轴偏心距为主要变量，对 60 个 H 型截面铝合金穿孔构件进行了偏心压缩试验。试验结果表明，试样出现了明显的侧向屈曲。研究了腹板开孔对构件屈曲模式、稳定承载力、纵向变形、横向变形和应变发展的影响。研究了各变量对力学性能的影响，为结构构件的设计提供了依据。利用经过验证的有限元模型对几个主要参数进行了深入分析。根据试验和有限元分析的结果，参照现有规范，提出了 H 型截面铝合金穿孔构件横向稳定承载力的设计方法。