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【新文速递】2024年7月27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 2 篇,Mechanics of Materials 1 篇,Thin-Walled Structures 3 篇

International Journal of Solids and Structures

A parametrized continuum constitutive model for reinforced thermoplastic composites with mechanically interlocked interface

Anmol Kothari, Istemi B. Ozsoy, Gang Li

doi:10.1016/j.ijsolstr.2024.112994

具有机械互锁界面的增强热塑性复合材料的参数化连续本构模型

Reinforced thermoplastic composites (RTPC) exhibit weak interfacial strength due to the low surface energy of the polymer matrix. Recently, a concept of controlled mechanical interlocking was introduced that showed significant improvement in the interfacial shear strength with pure mechanical interlocking and no chemical bond/friction. In this paper, a parameterized continuum material model is developed through computational homogenization for an E-glass/polypropylene (PP) composite system with a mechanically interlocked interface. Such parametric models not only elucidate the effects of the microstructural parameters on the mechanical behavior of the material but also enables the optimization of the composite at the microstructure level.

增强热塑性复合材料(RTPC)由于聚合物基体表面能低而表现出较弱的界面强度。最近,一种受控机械联锁的概念被引入,在纯机械联锁而没有化学键/摩擦的情况下,界面抗剪强度得到了显著提高。本文通过计算均质化,建立了具有机械互锁界面的e -玻璃/聚丙烯(PP)复合材料体系的参数化连续材料模型。这些参数化模型不仅阐明了微观结构参数对材料力学行为的影响,而且能够在微观结构水平上对复合材料进行优化。


Constitutive description of distortional hardening in a TWIP steel: Addressing differential hardening under nonlinear strain paths

Kang Wu, Chengchao Fang, Yong Sun, Jun Yang

doi:10.1016/j.ijsolstr.2024.113000

TWIP钢变形硬化的本构描述:处理非线性应变路径下的差异硬化

The present study aims to describe the in-plane differential hardening behaviour of the twinning induced plasticity sheet metal TWIP980 under various stress states, including uniaxial tension, plane strain tension, and pure shear, particularly focusing on non-proportional loading conditions. The true stress–strain curves for each stress states were inversely obtained from their corresponding load–displacement curves and modeled using a differential hardening model that can accommodate all three stress states simultaneously on plastic work (density) contours. For non-proportional loading tests, oversize specimens were initially stretched under uniaxial tension up to a 10% pre-strain along the rolling, diagonal, and transverse directions, respectively. Subsequently, the three stress states were applied to subsize specimens cut from the deformed oversize specimens along the rolling direction. To describe the hardening behaviours during non-proportional loading, a homogeneous anisotropic hardening model was adopted and calibrated using two-step uniaxial tension tests. Subsequently, the differential hardening model was successfully incorporated into the homogeneous anisotropic hardening model to describe both the differential hardening and the strain path change-induced hardening behaviours under the two-step loadings, i.e., uniaxial tension to pure shear and uniaxial tension to plane strain tension. Both experimental and simulation results underscore the necessity to consider differential hardening under non-proportional loading conditions.

本研究旨在描述双晶诱导塑性板材TWIP980在不同应力状态下的面内差异硬化行为,包括单轴拉伸、平面应变拉伸和纯剪切,特别关注非比例加载条件。每个应力状态下的真实应力-应变曲线由其对应的载荷-位移曲线反向获得,并使用微分硬化模型建模,该模型可以同时在塑性工作(密度)轮廓上容纳所有三种应力状态。对于非比例加载试验,超大试件在单轴拉伸下分别沿滚动、对角线和横向拉伸至10%的预应变。随后,将这三种应力状态应用于从变形的超大尺寸试样上沿轧制方向切割的亚尺寸试样。为了描述非比例加载时的硬化行为,采用均匀各向异性硬化模型,并采用两步单轴拉伸试验进行校准。随后,将差异硬化模型成功地纳入均匀各向异性硬化模型,以描述单轴拉伸到纯剪切和单轴拉伸到平面应变拉伸两步加载下的差异硬化和应变路径变化引起的硬化行为。实验和模拟结果都强调了在非比例加载条件下考虑差异硬化的必要性。


Journal of the Mechanics and Physics of Solids

The adjustable adhesion strength of multiferroic composite materials via electromagnetic loadings and shape effect of punch

Qing-Hui Luo, Yue-Ting Zhou, Yuxiao Yang, Shenghu Ding, Lihua Wang

doi:10.1016/j.jmps.2024.105794

利用电磁载荷和冲头形状效应调节多铁复合材料的粘接强度

Tunable and reversible dry adhesion possess great potential in a wide range of applications including transfer printing, climbing robots, wearable devices/electronics, and gripping in pick-and-place operations. Multiferroic composite materials offer new routines and approaches to achieve tunable adhesion due to their multi-field coupling effects. In this paper, the classical Johnson-Kendall-Roberts (JKR) adhesion model is extended to investigate the adhesive contact problem of a multiferroic composite half-space indented by an axisymmetric power-law shaped punch, whose shape index is denoted by n. The JKR-n adhesion models under the action of the power-law shaped punches with four different electromagnetic properties are set up by means of the total energy method. The explicit analytical expressions relating the indentation load and indentation depth to the contact radius are obtained, which can include the existing results in open literature as special cases. The generalized Tabor parameter and the interfacial adhesion strength applicable to multiferroic composite materials are defined. The effects of the shape index and the electromagnetic loadings on adhesion behaviors are revealed. It is found that both of them have prominent influences on the relationships among the indentation load, indentation depth and contact radius, the contact radius and indentation depth at self-equilibrium state, and the critical contact radius and indentation depth at pull-off moment. The pull-off force under the action of the conducting spherical punch subjected to non-zero electromagnetic loadings is dependent on material properties, which is different from the classical JKR result. More importantly, our analysis indicates that the pull-off force and the interfacial adhesion strength can be adjusted via altering the electromagnetic loadings and the shape index of the punch, which provides new approaches to achieve tunable adhesion.

可调和可逆的干粘附在广泛的应用中具有巨大的潜力,包括转移印刷,攀爬机器人,可穿戴设备/电子产品,以及在拾取和放置操作中的抓取。多铁复合材料由于其多场耦合效应,为实现可调粘附提供了新的思路和方法。本文将经典的Johnson-Kendall-Roberts (JKR)粘接模型推广到研究形状指数为n的轴对称幂律型冲头压痕下多铁复合材料半空间的粘接接触问题。利用总能量法建立了四种不同电磁性能幂律型冲头作用下的JKR-n粘接模型。得到了压痕载荷和压痕深度与接触半径的显式解析表达式,作为特例可以包括公开文献中已有的结果。定义了适用于多铁复合材料的广义Tabor参数和界面粘接强度。揭示了形状指数和电磁载荷对粘接性能的影响。发现两者对压痕载荷、压痕深度与接触半径、自平衡状态下的接触半径与压痕深度、拉脱时刻临界接触半径与压痕深度之间的关系有显著影响。在非零电磁载荷作用下,导电球冲头的拉脱力取决于材料的性质,这与经典的JKR结果不同。更重要的是,我们的分析表明,拉拔力和界面粘附强度可以通过改变电磁载荷和冲头的形状指标来调节,这为实现可调粘附提供了新的途径。


Pressurized membranes between walls: Thermodynamic process changes force and stiffness

Paul Lacorre, Louison Fiore, Jean-Marc Linares, Loïc Tadrist

doi:10.1016/j.jmps.2024.105798

壁间加压膜:热力学过程改变了力和刚度

Pressurized solids are ubiquitous in nature. Mechanical properties of biological tissues arise from cell turgor pressure and membrane elasticity. Flat contact between cells generate nonlinear forces. In this work, cells are idealized as pressurized elastic membranes in frictionless contact with one another. Contact forces are experimentally measured on rubber-like membranes and computed using finite element analysis (FEA). FEA matches experimental force-indentation relationships from small to large indentations. With the chosen dimensionless numbers, data gather on a master curve. The isobaric force exhibits a 4/3 power law over 1.5 decades of indentation. Forces for other thermodynamic processes (adiabatic, isothermal/osmotic and isochoric) are interpolated from isobaric data. Regarding stiffness, the isochoric process is superlinear contrary to the sublinear isobaric stiffness. Simple force-indentation relationships are given for each process.

加压固体在自然界中无处不在。生物组织的力学特性是由细胞的膨胀压力和膜的弹性决定的。单元间的平面接触产生非线性力。在这项工作中,细胞被理想化为彼此无摩擦接触的加压弹性膜。实验测量了类橡胶膜上的接触力,并用有限元法计算了接触力。有限元分析从小到大的压痕匹配实验力-压痕关系。有了选定的无量纲数,数据就会在一条主曲线上收集。等压力在15年的压痕中呈现4/3幂律。其他热力学过程(绝热、等温/渗透和等时)的力由等压数据插值。在刚度方面,等压过程与次线性等压刚度相反是超线性的。给出了每个过程的简单力-压痕关系。


Mechanics of Materials

Carbon nanotubes as a basis of metamaterials and nanostructures: Crafting via design optimization

Marko Čanađija, Stefan Ivić

doi:10.1016/j.mechmat.2024.105105

碳纳米管作为超材料和纳米结构的基础:通过设计优化制作

Nanotruss structures made of carbon nanotubes are investigated in two conceptual applications: either as building blocks of metamaterials or for nanostructural applications. The nanotrusses are optimized for different purposes, including various loadings, boundary conditions, parameterizations, objectives and constraints used to formulate optimization problems. The procedure relies on a recently developed framework consisting of molecular dynamics simulations, neural networks and finite elements. This framework is now used in the design optimization of nanostructures and the performances of different popular heuristic optimization methods are compared. Five applications of nanotrusses made of carbon nanotubes are analyzed in detail to investigate the mechanical behavior of such structures and the efficiency of the optimizations. Besides an introductory example, the design of an energy trapping carbon nanotube nanotruss, an auxetic nanotruss, a cantilever nanotruss and the maximization of the compressive strength of a metamaterial are presented. It is shown that the exceptional mechanical properties of carbon nanotubes can indeed be exploited for the development of structures and materials with extraordinary mechanical properties. Although hampered by material and geometrical nonlinearity of the problem, most of the tested optimization methods have proven to be a good choice for the design of such materials and structures.

由碳纳米管制成的纳米桁架结构在两个概念上的应用:作为超材料的构建块或用于纳米结构应用。纳米桁架针对不同的目的进行了优化,包括各种负载、边界条件、参数化、目标和约束,用于制定优化问题。该程序依赖于最近开发的由分子动力学模拟、神经网络和有限元组成的框架。该框架目前已用于纳米结构的设计优化,并比较了不同流行的启发式优化方法的性能。详细分析了碳纳米管纳米桁架的五种应用,研究了这种结构的力学性能和优化的效率。此外,还介绍了能量捕获型碳纳米管纳米桁架、辅助型纳米桁架、悬臂型纳米桁架以及超材料抗压强度最大化的设计方法。研究结果表明,碳纳米管优异的力学性能确实可以用于开发具有优异力学性能的结构和材料。虽然受到材料和几何非线性问题的限制,但大多数经过试验的优化方法已被证明是这类材料和结构设计的良好选择。


Thin-Walled Structures

Behaviour, finite element modelling and design of flanged cruciform section steel columns

Ruikai Dai, Behnam Behzadi-Sofiani, Spiridione Buhagiar, M. Ahmer Wadee, Leroy Gardner

doi:10.1016/j.tws.2024.112268

法兰十字截面钢柱的性能、有限元建模与设计

A study into the mechanical behaviour and design of flanged cruciform section steel members subjected to axial compression is presented herein. The mechanical behaviour of flanged cruciform section columns is first described, with particular emphasis on the newly developed approach for determining the elastic local buckling load for full flanged cruciform cross-sections. Existing experimental data on flanged cruciform section steel columns collected from the literature are then employed to validate numerical models developed within the finite element package ABAQUS. A comprehensive parametric study is subsequently conducted that encompasses a broad spectrum of cross-sectional geometries and global slenderness values. The mechanical behaviour and ultimate resistance of flanged cruciform section columns are shown to be dependent on not only the global slenderness, but also on the ratio of the elastic torsional to flexural buckling loads. The existing experimental data alongside the numerical parametric study results are employed to evaluate the resistance predictions provided in the current Eurocode 3 design codes, revealing a high level of conservatism. Finally, a new design approach for flanged cruciform section columns, suitable for incorporation into future revisions of Eurocode 3, is proposed which provides significantly improved accuracy and consistency in resistance predictions compared with the current provisions. A reliability analysis of the proposed design approach is conducted in accordance with the EN 1990 procedure, resulting in a recommended partial safety factor γ M1 = 1 . 0 .

本文研究了十字形法兰型钢构件在轴压作用下的受力性能及设计。首先描述了法兰十字形截面柱的力学行为,特别强调了确定全法兰十字形截面弹性局部屈曲载荷的新方法。从文献中收集的法兰十字形截面钢柱的现有实验数据,然后用于验证在有限元软件包ABAQUS中开发的数值模型。随后进行了全面的参数化研究,包括广泛的横截面几何形状和整体长细比值。结果表明,法兰十字形截面柱的力学性能和极限抗力不仅与整体长细比有关,而且与弹性扭转载荷与弯曲屈曲载荷的比值有关。利用现有的实验数据和数值参数研究结果对现行欧洲规范3设计规范中提供的阻力预测进行了评估,显示出高度的保守性。最后,提出了一种新的法兰十字形截面柱的设计方法,适合纳入欧洲规范3的未来修订,与现行规定相比,该方法在阻力预测方面提供了显着提高的准确性和一致性。根据en1990程序对建议的设计方法进行可靠性分析,得出建议的部分安全系数γ M1 = 1。0。


Flexible Roll Forming of surface developable profiles from Dual Phase steel.

Achuth Sreenivas, Buddhika Abeyrathna, Bernard Rolfe, Matthias Weiss

doi:10.1016/j.tws.2024.112271

双相钢表面可展型材的柔性辊压成形。

Flexible Roll Forming (FRF) can roll-form variable cross-sectional profiles for Electric Vehicle (EV) production however, a major limitation exists due to flange wrinkling while forming high-strength steels. Flange wrinkling can be eliminated by reducing the required level of membrane deformation in the longitudinal direction. Although reducing the severity of the profile's transitions minimises the strains, the overall complexity of the parts is also lowered. Origami-based developable profiles can be created from curved creased folding without membrane stretching or compression. In FRF, such types of profiles can be formed by combining a variation in width and depth over the length of the part. This study presents, for the first time, the analyses of forming a developable shape in a FRF operation. Firstly, analytical equations are applied to calculate the strains and forming stability of each pass which is followed by experimental FRF trials on two high-strength Dual Phase steels. Finally, Finite Element Analysis is used to investigate the forming behaviour of the two types of developable profiles. The experimental results show that the forming of one type of developable profile improves the shape, while the numerical analyses showed that an additional top-hat forming is required for the second profile type.

柔性辊压成形(FRF)可以轧制出电动汽车(EV)生产的可变截面型材,但在成形高强度钢时存在法兰起皱的主要限制。可以通过降低纵向所需的膜变形水平来消除法兰起皱。虽然降低了型材过渡的严重程度,最大限度地减少了应变,但零件的整体复杂性也降低了。折纸为基础的可展轮廓可以创建从弯曲折痕折叠膜拉伸或压缩。在频响中,这种类型的轮廓可以通过结合零件长度上的宽度和深度变化来形成。本研究首次提出了在频响操作中形成可展开形状的分析。首先用解析方程计算了各道次的应变和成形稳定性,然后对两种高强度双相钢进行了频响试验。最后,采用有限元分析方法研究了两种可展开型材的成形行为。实验结果表明,一种可展开轮廓的成形可以改善形状,而数值分析表明,第二种轮廓需要额外的顶帽成形。


Metamaterial design enabling simultaneous manipulation of Rayleigh and Love waves

Jia Lou, Hui Fan, Jie Yang, Menghui Xu, Jianke Du

doi:10.1016/j.tws.2024.112273

可以同时操纵瑞利波和洛夫波的超材料设计

Studies on elastic metamaterials have expanded from manipulating bulk waves to surface waves, aiming to control the propagation of in-plane Rayleigh waves or anti-plane Love waves. Considering the coexistence of Rayleigh and Love waves in various scenarios, the objective of this study is to develop a metamaterial capable of simultaneously manipulating both types of waves. The proposed metamaterial consists of horizontal resonators with an oblique mounting angle relative to the wave propagation direction, as well as vertical resonators. Initially, analytical solutions for the dispersion of surface waves are derived, followed by Finite Element (FE) simulations to validate the analytically predicted dispersion and illustrate the corresponding wave modes, as well as the in-plane and out-of-plane displacement fields at specified frequencies. The present study reveals that the mounting angle of the horizontal resonators plays a crucial role in surface wave manipulation. By adjusting the mounting angle, three distinct objectives can be achieved: i) the attenuation of Rayleigh waves alone; ii) the independent attenuation of Rayleigh and Love waves, targeting different frequency ranges; and iii) the simultaneous attenuation of both Rayleigh and Love waves.

弹性超材料的研究已经从控制体波扩展到控制面波,目的是控制面内瑞利波或反面洛夫波的传播。考虑到瑞利波和洛夫波在各种情况下的共存,本研究的目标是开发一种能够同时操纵两种波的超材料。所提出的超材料包括相对于波传播方向具有倾斜安装角的水平谐振器以及垂直谐振器。首先推导了表面波色散的解析解,然后进行了有限元模拟,验证了解析预测的色散,并说明了相应的波模,以及在指定频率下的面内和面外位移场。研究表明,水平谐振器的安装角度对表面波控制起着至关重要的作用。通过调整安装角度,可以实现三个不同的目标:1)瑞利波的单独衰减;ii)针对不同频率范围的瑞利波和洛夫波的独立衰减;瑞利波和洛夫波同时衰减。



来源:复合材料力学仿真Composites FEM
ACTMechanicalSystemMarcAbaqus复合材料非线性化学汽车电子ECAD材料机器人分子动力学控制
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【新文速递】2024年8月1日固体力学SCI期刊最新文章

今日更新:Journal of the Mechanics and Physics of Solids 1 篇,Mechanics of Materials 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 3 篇Journal of the Mechanics and Physics of SolidsMechanochemical patterning and wave propagation in multicellular tubesPengyu Yu, Bo Lidoi:10.1016/j.jmps.2024.105801多细胞管中的机械化学模式和波传播Multicellular tubes are fundamental tissues for transporting and distributing liquids and gases in living organisms. Although the molecular, cellular and mechanical aspects in tube formation have been addressed experimentally, how these factors are coupled to control tube patterning and dynamics at the tissue level remains incompletely understood. Here, we propose a three-dimensional (3D) vertex model that incorporates a mechanochemical feedback loop correlating cell deformation and actomyosin signaling pathway to probe the morphodynamics of multicellular tubes. We show that diverse patterns, including ring, helix, double helix, and labyrinth, are generated in tubes through pitchfork bifurcation, where spatial fluctuations of both biochemical signaling and 3D cell deformation are remarkably involved. The mechanochemical feedback loop enables cell oscillations via Hopf bifurcation, which induces the mechanical and chemical patterns to propagate successively as either travelling or pulse waves while their spatial configurations are maintained, strikingly distinct from the classical Turing instability. Our simulations, together with stability analysis of a minimal model, uncover the essential role of mechanochemical principles in sculpting biological tubes.多细胞管是生物体内运输和分配液体和气体的基本组织。虽然试管形成的分子、细胞和力学方面已经在实验中得到了解决,但这些因素如何耦合到组织水平上控制试管的模式和动力学仍然不完全清楚。在这里,我们提出了一个三维(3D)顶点模型,该模型结合了与细胞变形和肌动球蛋白信号通路相关的机械化学反馈回路,以探测多细胞管的形态动力学。我们发现不同的模式,包括环,螺旋,双螺旋和迷宫,通过干草叉分叉在管中产生,其中生化信号和三维细胞变形的空间波动显著参与。机械化学反馈回路通过Hopf分岔使细胞振荡,这诱导机械和化学模式作为行波或脉冲波连续传播,同时保持它们的空间构型,与经典的图灵不稳定性明显不同。我们的模拟,连同最小模型的稳定性分析,揭示了机械化学原理在雕刻生物管中的重要作用。Mechanics of MaterialsMedium entropy alloy-induced strong size dependence in the strengthening and shear instability of nanolayered metallic compositesFeng Qin, Kaiqing Dai, Junhua Hou, Wenjun Lu, Shaohua Chen, Jianjun Lidoi:10.1016/j.mechmat.2024.105107中熵合金对纳米层金属复合材料的增强和剪切失稳具有很强的尺寸依赖性Medium/high entropy alloys (M/HEAs)-based nanolayered metallic composites have attracted intensive scientific interests due to their superior mechanical properties. However, the shear instability of the M/HEAs-based composites is rarely studied and the underlying mechanism remains uncovered. A combination of theoretical analysis and nano/microindentation tests was conducted to investigate the size-dependent strengthening and shear instability of Cu/CrCoNi composites. The results show that the shear banding-induced instability of the composites exhibit a clear transition from layer interfaces-mediated kinking to grain boundaries-accommodated one at a critical layer thickness of 25 nm, which apparently differs from those in traditional M/HEAs-free composites. The sudden change in the deformation mode originates from the MEA-induced size-dependent microstructure transformation, i.e., from horizontally aligned layer interfaces at large layer thicknesses to vertically aligned grain boundaries at small ones. The size-dependent strengthening and plasticity can be respectively captured by the confined layer slip model and the proposed theoretical model.中高熵合金(M/HEAs)基纳米层金属复合材料以其优异的力学性能引起了科学界的广泛关注。然而,对M/ heas基复合材料剪切失稳的研究很少,其潜在机制也尚未揭示。采用理论分析和纳米/微压痕试验相结合的方法研究了Cu/CrCoNi复合材料的尺寸依赖性强化和剪切不稳定性。结果表明,在25 nm的临界层厚处,剪切带诱导的复合材料的失稳表现出从层界面介导的扭结到晶界调节的扭结的明显转变,这与传统的无M/ heas复合材料明显不同。变形模式的突变源于mea诱导的尺寸相关的微观结构转变,即从大层厚处水平排列的层界面到小层厚处垂直排列的晶界。约束层滑移模型和本文提出的理论模型可以分别捕获与尺寸相关的强化和塑性。International Journal of PlasticityChromium Gradient Stainless Steels with Simultaneous High Strength, Ductility, and Corrosion-resistant: In-depth Study of Continuous Hardening MechanismsHaodi Yang, Zhutian Xu, Linfa Peng, Xinmin Lai, Mingwang Fudoi:10.1016/j.ijplas.2024.104082 同时具有高强度、延展性和耐腐蚀性的铬梯度不锈钢:连续硬化机制的深入研究Cr-rich stainless steel sheets exhibit superior corrosion resistance but low ductility, which presents a trade-off between fabrication complexity and performance of the materials in multiple industrial applications, such as marine equipment and microreactors. By transitioning the Cr-rich (30 wt.% Cr) stainless steel component to SS 316L with a smooth composition gradient in the thickness direction, the intrinsic homogeneous elongation of the Cr-rich layer was increased by 260 % while maintaining the naturally high corrosion resistance (100 %) and retaining most of the strength (more than 80 %). By employing in-situ tensile testing and electron backscatter diffraction analysis, it was revealed that the Cr-rich layer in the gradient structure underwent a profound deformation mechanism, including significant heterogeneous deformation-induced hardening and grain reorientation induced by multiplication and accumulation of geometrically necessary dislocations, in such a way to enable a substantial plastic strain and thereby retarding the occurrence of fracture. The proportion of the Cr-rich layer makes a significant impact on the magnitude of the strain gradient in the gradient specimens, therefore affecting the increment of density of geometrically necessary dislocations. The critical proportion value of the Cr-rich layer is found to be around 22 %. Before and after the critical value the gradient specimens showed different sensitivities to the proportion. This discovery underlines the significance of intrinsic plasticity in low-ductility metals and the role of compositional gradient materials in enhancing strength and ductility.富铬不锈钢板具有优异的耐腐蚀性,但延展性低,这在多种工业应用(如船舶设备和微反应器)中提出了制造复杂性和材料性能之间的权衡。通过将富Cr (30wt .% Cr)不锈钢组分转变为具有光滑厚度梯度的SS 316L,富Cr层的本构均匀伸长率提高了260%,同时保持了天然的高耐腐蚀性(100%)和大部分强度(80%以上)。通过原位拉伸测试和电子背散射衍射分析,发现梯度结构中的富cr层发生了深刻的变形机制,包括显著的非均质变形诱导的硬化和几何必要位错的增殖和积累引起的晶粒重定向,从而产生了大量的塑性应变,从而延缓了断裂的发生。富cr层的比例对梯度试样中应变梯度的大小有显著影响,从而影响几何必要位错密度的增量。富cr层的临界比例值在22%左右。在临界值前后,梯度试样对比例的敏感性不同。这一发现强调了低延性金属的内在塑性的重要性,以及成分梯度材料在提高强度和延性方面的作用。Thin-Walled StructuresExperimental, numerical, and analytical studies of asymmetric bolted square hollow section splices in bendingRui Yan, Milan Veljkovic, Luís Simões Da Silvadoi:10.1016/j.tws.2024.112282非对称螺栓方空心截面接头弯曲的实验、数值和分析研究The flexural behaviour of two types of asymmetric bolted square hollow section (SHS) splices is investigated in this paper. The asymmetric bolted SHS splices are derived from the traditional bolted end plate SHS joints but with the end plate flushed to the SHS surface on one side or two adjacent sides, where a cover plate connects two SHSs. Firstly, four-point bending tests are conducted for two configurations under different loading conditions. Next, finite element (FE) analysis is carried out to simulate the experiments. To reduce the computational time, a simplified FE model is developed, which is further employed for a parametric study. Finally, the component method, which was extended for the asymmetric bolted SHS splices under tensile load, is verified against the FE models in the parametric study. The results show that the extended component method could effectively predict the stiffness and the resistance of bolted asymmetric SHS splices under different bending loads.本文研究了两种非对称螺栓方空心截面(SHS)接头的抗弯性能。非对称螺栓连接SHS是在传统螺栓端板SHS连接的基础上发展而来的,但其端板在一侧或相邻的两侧冲到SHS表面,其中盖板连接两个SHS。首先,对两种结构进行了不同加载条件下的四点弯曲试验。其次,对实验进行了有限元模拟分析。为了减少计算时间,建立了一个简化的有限元模型,并将其进一步用于参数化研究。最后,通过参数化研究中的有限元模型验证了对拉伸载荷作用下非对称螺栓SHS接头的构件分析方法。结果表明,扩展分量法可以有效地预测不同弯曲载荷下螺栓非对称SHS接头的刚度和阻力。Nonlinear vibrations of variable speed rotating graphene platelets reinforced blades subjected to combined parametric and forced excitationJin-Peng Song, Gui-Lin She, M.A. Eltaherdoi:10.1016/j.tws.2024.112283参数激励与强制激励联合作用下石墨烯片增强叶片的非线性振动It is generally acknowledged that the disturbance of rotating speed will cause parametric resonance for blades, and the presence of rotor displacement also can make the blade vibrate transversely. However, the coupled resonance mechanism of blades under the combined action of rotating speed disturbance and rotor displacement is not yet clear. To answer this question, this article investigates the nonlinear coupled resonance behavior of rotating blades in two cases: typical tuned (the frequency ratio of parametric and forced excitations equals 2:1) and frequency ratio detuned. A nonlinear vibration equation for rotating blades is established based on Euler beam theory in conjunction with geometric nonlinearity. The mixing rule and modified Halpin-Tsai model are used to calculate the effective properties of GPLRMF materials. Subsequently, using the method of varying amplitudes (MVA), an approximate analytical solution of the coupled resonance response is derived, the Jacobian matrix is used to determine the stability of non-trivial solutions, and the accuracy of the analytical results is verified with the aid of numerical solutions. Finally, the steady-state response of typical tuned and detuned coupled resonance is analyzed, and the influence mechanism of factors such as excitation amplitude, excitation phase angle and other parameters on coupled resonance is studied in detail. The results indicate that the supercritical coupled resonance curve exhibits double resonance peaks and jumps. Meanwhile, the steady-state response of coupled resonance highly depends on the excitation phase angle.一般认为转速的扰动会引起叶片的参数共振,转子位移的存在也会使叶片产生横向振动。然而,叶片在转速扰动和转子位移共同作用下的耦合共振机理尚不清楚。为了回答这个问题,本文研究了两种情况下旋转叶片的非线性耦合共振行为:典型调谐(参数激励与强迫激励的频率比等于2:1)和频率比调谐。基于欧拉梁理论,结合几何非线性,建立了旋转叶片的非线性振动方程。采用混合规则和修正的Halpin-Tsai模型计算了GPLRMF材料的有效性能。随后,采用变幅法推导了耦合共振响应的近似解析解,利用雅可比矩阵确定了非平凡解的稳定性,并借助数值解验证了解析结果的准确性。最后,分析了典型调谐和失调谐耦合谐振的稳态响应,详细研究了激励幅值、激励相位角等参数对耦合谐振的影响机理。结果表明,超临界耦合共振曲线呈现双共振峰和双共振跳变。同时,耦合谐振的稳态响应高度依赖于激励相位角。Cushioning Performance of Origami Negative Poisson's ratio Honeycomb Steel StructureYiyi Zhou, Dan Jiang, Lu Wang, Ping Xiang, Liang-Jiu Jiadoi:10.1016/j.tws.2024.112284折纸负泊松比蜂窝钢结构的减震性能The honeycomb structure with a negative Poisson's ratio, inspired by the Miura origami unit, exhibits three-dimensional negative Poisson's ratio characteristics and effective energy dissipation performance. This unique property provides significant potential in the field of protection applications. This study aims to comprehensively understand the impact of auxetic and origami structures on the cushioning performance of honeycomb structures. For this purpose, 316L stainless steel specimens were fabricated using 3D printing technology and subjected to drop hammer impact tests, and the results were verified by finite element simulation. This paper focuses on assessing the deformation mode and energy dissipation performance of origami auxetic honeycomb structures with varying width-to-thickness ratios and folding angles under different impact energy levels. The results indicate that the negative Poisson's ratio origami specimens exhibit higher plateau stress and specific energy absorption compared to their positive and zero Poisson's ratio origami counterparts with the same geometry. In addition, a smaller width-to-thickness ratio and higher input impact energy enhance the cushioning performance of honeycomb structures.负泊松比的蜂窝结构,受折纸单元的启发,具有三维负泊松比特性和有效的能量耗散性能。这种独特的特性在保护应用领域提供了巨大的潜力。本研究旨在全面了解辅助结构和折纸结构对蜂窝结构缓冲性能的影响。为此,采用3D打印技术制作316L不锈钢试件,进行落锤冲击试验,并通过有限元模拟对结果进行验证。研究了在不同冲击能级下,不同宽厚比和折叠角度的折纸减振蜂窝结构的变形模式和耗能性能。结果表明,与相同几何形状的正泊松比和零泊松比折纸相比,负泊松比折纸具有更高的平台应力和比能吸收。此外,较小的宽厚比和较高的输入冲击能增强了蜂窝结构的缓冲性能。来源:复合材料力学仿真Composites FEM

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