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Mechanical responses and crystal plasticity model of CoCrNi medium-entropy alloy under ramp wave compression

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Matter and Radiation at Extremes 2024年第5期9卷 93-108页

作者： Jinlei Dong Xuping Zhang Guiji Wang Xianqian Wu Binqiang Luo Xuemiao Chen Fuli Tan Jianheng Zhao Chengwei Sun Institute of Fluid Physics China Academy of Engineering PhysicsMianyang 621999China Institute of mechanics Chinese Academy of SciencesBeijing 100190China Institute of applied Electronics China Academy of Engineering PhysicsMianyang 621999China

It is of substantial scientific significance and practical value to reveal and understand the multiscale mechanical properties and intrinsic mechanisms of medium-entropy alloys(MEAs)under high strain rates and *** this study,the mechanical responses and deformation mechanisms of an equiatomic CoCrNi MEA are investigated utilizing magnetically driven ramp wave compression(RWC)with a strain rate of 105 s^(−1).The CoCrNi MEA demonstrates excellent dynamic mechanical responses and yield strength under RWC compared with other advanced *** characterizations reveal that grain refinement and abundant micromechanisms,including dislocation slip,stacking faults,nanotwin network,and Lomer–Cottrell locks,collectively contribute to its excellent performance during ***,dense deformation twins and shear bands intersect,forming a weave-like microstructure that can disperse deformation and enhance *** the basis of these observations,we develop a modified crystal plasticity model with coupled dislocation and twinning mechanisms,providing a relatively accurate quantitative description of the multiscale behavior under *** results of simulations indicate that the activation of multilevel microstructures in CoCrNi MEA is primarily attributable to stress inhomogeneities and localized strain during *** research offers valuable insights into the dynamic mechanical responses of CoCrNi MEA,positioning it as a promising material for use under extreme dynamic conditions.

关键词： deformation alloy microstructure

An inverse method for characterization of dynamic response of 2D structures under stochastic conditions

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Chinese Journal of Aeronautics 2024年第3期37卷 440-455页

作者： Xuefeng LI Abdelmalek ZINE Mohamed ICHCHOU Noureddine BOUHADDI Pascal FOSSAT Laboratory of Tribology and Systems Dynamic Central School of LyonEcully 69134France Institut Camille Jordan Central School of LyonEcully 69134France Department of applied mechanics University of Burgundy Franche-ComtéBesancon 25000France

The reliable estimation of the wavenumber space(k-space)of the plates remains a longterm concern for acoustic modeling and structural dynamic behavior *** current analyses of wavenumber identification methods are based on the deterministic *** this end,an inverse method is proposed for identifying wave propagation characteristics of twodimensional structures under stochastic conditions,such as wavenumber space,dispersion curves,and band *** proposed method is developed based on an algebraic identification scheme in the polar coordinate system framework,thus named Algebraic K-Space Identification(AKSI)***,a model order estimation strategy and a wavenumber filter are proposed to ensure that AKSI is successfully *** main benefit of AKSI is that it is a reliable and fast method under four stochastic conditions:(A)High level of signal noise;(B)Small perturbation caused by uncertainties in measurement points’coordinates;(C)Non-periodic sampling;(D)Unknown structural *** validate the proposed method,we numerically benchmark AKSI and three other inverse methods to extract dispersion curves on three plates under stochastic *** experiment is then performed on an isotropic steel *** investigations demonstrate that AKSI is a good in-situ k-space estimator under stochastic conditions.

关键词： Inverse method Dispersion relation Wavenumber space Periodic plates Stochastic conditions Wave propagation characterization

镁单晶塑性变形行为的晶体塑性耦合孪晶相场模拟

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Acta Mechanica Sinica 2024年第3期40卷 123-144页

作者：胡佳晨徐波于超康国政 applied mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Aerospace EngineeringSouthwest Jiaotong UniversityChengdu611756China Failure mechanics and Engineering Disaster Prevention Key Laboratory of Sichuan ProvinceSichuan UniversityChengdu610065China Institute of applied mechanics State Key Laboratory of Traction PowerSouthwest Jiaotong UniversityChengdu610031China

本文建立了一个晶体塑性-孪晶相场耦合模型来研究镁单晶的塑性变形行为.在晶体塑性模型中考虑了三种典型的滑移模式,即基面滑移、柱面滑移、锥面滑移,而在孪晶相场模型中考虑了化学能、梯度能和弹性能的作用.模拟结果表明:在沿孪生方向... 详细信息

本文建立了一个晶体塑性-孪晶相场耦合模型来研究镁单晶的塑性变形行为.在晶体塑性模型中考虑了三种典型的滑移模式,即基面滑移、柱面滑移、锥面滑移,而在孪晶相场模型中考虑了化学能、梯度能和弹性能的作用.模拟结果表明:在沿孪生方向剪切加载诱导孪晶的过程中,不同阶段的应力水平和不同方向孪晶界面的迁移率存在较大差异.孪晶在早期呈透镜状,而在侧向长大阶段呈平板状,并且孪晶出现后有基面滑移被激活;非基面滑移在基体完全转变为孪晶后被激活.在一个拉-压载荷周期内,不同取向的镁单晶中出现不同的塑性变形模式,当加载方向平行于c轴时,对应的变形模式为孪生-解孪-锥面滑移-复孪生;当加载方向垂直于c轴时,对应的变形模式为柱面滑移-柱面滑移孪生-孪生-解孪,这两种单晶均表现出强拉压不对称性;当加载方向与c轴夹角为45°时,仅发生基面滑移,不存在拉压不对称现象.

关键词： Magnesium single crystal Phase field model Twinning Dislocation slipping Crystalline orientation

A vertical track nonlinear energy sink

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applied Mathematics and mechanics(English Edition) 2024年第6期45卷 931-946页

作者： Meng LI Hu DING Shanghai Key Laboratory of mechanics in Energy Engineering School of Mechanics and Engineering ScienceShanghai Frontier Science Center of MechanoinformaticsShanghai UniversityShanghai 200444China

Eliminating the effects of gravity and designing nonlinear energy sinks(NESs)that suppress vibration in the vertical direction is a challenging task with numerous damping *** this paper,the dynamic design of a vertical track nonlinear energy sink(VTNES)with zero linear stiffness in the vertical direction is proposed and realized for the first *** motion differential equations of the VTNES coupled with a linear oscillator(LO)are *** the strong nonlinearity considered of the VTNES,the steady-state response of the system is analyzed with the harmonic balance method(HBM),and the accuracy of the HBM is verified *** this basis,the VTNES prototype is manufactured,and its nonlinear stiffness is *** damping effect and dynamic characteristics of the VTNES are studied theoretically and *** results show that the VTNES has better damping effects when strong modulation responses(SMRs)***,even for small-amplitude vibration,the VTNES also has a good vibration suppression *** sum up,in order to suppress the vertical vibration,an NES is designed and developed,which can suppress the vertical vibration within certain ranges of the resonance frequency and the vibration intensity.

关键词： track nonlinear energy sink(TNES) vertical direction gravity nonlinear stiffness harmonic balance method(HBM) vibration control

非倒平方根应力奇异性对水力压裂某些裂纹扩展准则的影响

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Acta Mechanica Sinica 2024年第5期40卷 90-102页

作者：沈文豪吴璇黄先富 College of Mechanical and Vehicle Engineering Taiyuan University of Technology Taiyuan China Institute of applied mechanics Taiyuan University of Technology Taiyuan China State Key Laboratory of Nonlinear mechanics Institute of Mechanics Chinese Academy of Sciences Beijing China

水力压裂的数值研究可采用不同的裂纹扩展准则,其中一些准则依赖于线弹性断裂力学的假设,即存在倒平方根应力奇异性和椭圆裂纹轮廓。然而,水力压裂的裂纹尖端可能表现出更弱的应力奇异性,这种现象由称为表观断裂韧性的无量纲参数控制,... 详细信息

水力压裂的数值研究可采用不同的裂纹扩展准则,其中一些准则依赖于线弹性断裂力学的假设,即存在倒平方根应力奇异性和椭圆裂纹轮廓。然而,水力压裂的裂纹尖端可能表现出更弱的应力奇异性,这种现象由称为表观断裂韧性的无量纲参数控制,该参数表示使固体破裂所需的能量与克服流体摩擦所需的能量的比.在流体黏度占主导的情况下,表观断裂韧性从正数一侧趋近于零,应力奇异性阶次降低.当采用一些裂纹扩展准则计算时,结果可能会发生变化,主要是由于倒平方根应力奇异性发生改变,本文采用平直裂纹的数学模型来研究这种现象.在相同的数学模型中分别采用4种常用裂纹扩展准则,使用基于修正切比雪夫多项式和隐式时间积分的高精度方法进行计算。发现瞬态裂缝尺寸和井筒压力在使用不同裂纹扩展准则时存在差异。值得注意的是,当表观断裂韧性小于1.0时,裂纹尖端张开位移准则、连续介质损伤模型和断裂过程区准则在流体黏度占主导的情况下的计算模型很难收敛,本文基于裂纹尖端渐近性质讨论了其中隐含的机制.本文研究为水力压裂中裂缝扩展准则的选择提供了理论基础。

关键词：裂纹尖端张开位移切比雪夫多项式线弹性断裂力学流体摩擦应力奇异性参数表示无量纲参数椭圆裂纹

Analysis of piezoelectric semiconductor fibers under gradient temperature changes

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applied Mathematics and mechanics(English Edition) 2024年第2期45卷 311-320页

作者： Shuangpeng LI Ruoran CHENG Nannan MA Chunli ZHANG Department of Engineering mechanics Zhejiang UniversityHangzhou 310027China

Piezoelectric semiconductors(PSs)possess both semiconducting properties and piezoelectric coupling effects,making them optimal building blocks for semiconductor *** fiber-like structures have wide applications in multi-functional semiconductor *** this paper,a one-dimensional(1D)theoretical model is established to describe the piezotronic responses of a PS fiber under gradient temperature *** theoretical model aims to explain the mechanism behind the resistance change caused by such gradient temperature *** results demonstrate that a gradient temperature change significantly affects the physical fields within the PS fiber,and can induce changes in its surface *** provides important theoretical guidance on the development of piezotronic devices that are sensitive to temperature effects.

关键词： piezoelectric semiconductor(PS)fiber one-dimensional(1D)model piezotronic effect gradient temperature change

Analysis of the discrete contact characteristics based on the Greenwood-Williamson model and the localization principle

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Friction 2024年第5期12卷 1042-1056页

作者： Anastasiya A.YAKOVENKO Irina G.GORYACHEVA Ishlinsky Institute for Problems in mechanics RAS Moscow119526Russia

The contact of a rigid body with nominally flat rough surface and an elastic half-space is *** solve the contact problem,the Greenwood-Williamson statistical model and the localization principle are *** developed contact model allows us to investigate the surface approach and the real contact area with taking into account the asperities *** is shown that the mutual influence of asperities changes not only contact characteristics at the macroscale,but also the contact pressure distribution at the *** follows from the results,the inclusion in the contact model of the effect of the mutual influence of asperities is especially significant for studying the real contact area,as well as the contact characteristics at high applied *** results calculated according to the proposed approach are in a good agreement with the experimentally observed effects,i.e.,the real contact area saturation and the additional compliance exhaustion.

关键词： surface roughness elasticity Greenwood-Williamson model localization principle asperity interaction

Dynamic performance and parameter optimization of a half-vehicle system coupled with an inerter-based X-structure nonlinear energy sink

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applied Mathematics and mechanics(English Edition) 2024年第1期45卷 85-110页

作者： Yong WANG Peili WANG Haodong MENG Liqun CHEN .Automotive Engineering Research Institute Jiangsu UniversityZhenjiang 212013Jiangsu ProvinceChina Guangxi Key Laboratory of Automobile Components and Vehicle Technology Guangxi University of Science and TechnologyLiuzhou 545006Guangxi Zhuang Autonomous RegionChina School of Automotive Engineering Changzhou Institute of TechnologyChangzhou 213032Jiangsu ProvinceChina Shanghai Key Laboratory of mechanics in Energy Engineering Shanghai Frontier Science Center of MechanoinformaticsShanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200444China

Inspired by the demand of improving the riding comfort and meeting the lightweight design of the vehicle, an inerter-based X-structure nonlinear energy sink(IXNES) is proposed and applied in the half-vehicle system to enhance the dynamic performance. The X-structure is used as a mechanism to realize the nonlinear stiffness characteristic of the NES, which can realize the flexibility, adjustability, high efficiency, and easy operation of nonlinear stiffness, and is convenient to apply in the vehicle suspension, and the inerter is applied to replacing the mass of the NES based on the mass amplification characteristic. The dynamic model of the half-vehicle system coupled with the IX-NES is established with the Lagrange theory, and the harmonic balance method(HBM) and the pseudo-arc-length method(PALM) are used to obtain the dynamic response under road harmonic excitation. The corresponding dynamic performance under road harmonic and random excitation is evaluated by six performance indices, and compared with that of the original half-vehicle system to show the benefits of the IX-NES. Furthermore, the structural parameters of the IX-NES are optimized with the genetic algorithm. The results show that for road harmonic and random excitation, using the IX-NES can greatly reduce the resonance peaks and root mean square(RMS) values of the front and rear suspension deflections and the front and rear dynamic tire loads, while the resonance peaks and RMS values of the vehicle body vertical and pitching accelerations are slightly *** the structural parameters of the IX-NES are optimized, the vehicle body vertical and pitching accelerations of the half-vehicle system could reduce by 2.41% and 1.16%,respectively, and the other dynamic performance indices are within the reasonable ***, the IX-NES combines the advantages of the inerter, X-structure, and NES, which improves the dynamic performance of the half-vehicle system and provides an effective option for vibrati

关键词： inerter X-structure nonlinear energy sink(NES) half-vehicle system dynamic performance

Molding simulation of airfoil foam sandwich structure and interference optimization of foam-core

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Chinese Journal of Aeronautics 2024年第10期37卷 325-338页

作者： Qianying CEN Zeyang XING Qingyou WANG Lili LI Zhigang WANG Zhanjun WU Ling LIU School of Aerospace Engineering&applied mechanics Tongji UniversityShanghai 200092China AVIC Harbin Aircraft Industry Group Co.Ltd Harbin 150066China School of Aeronautics and Astronautics Dalian University of TechnologyDalian 116024China

During the Co-Cure Molding(CCM)of airfoil foam sandwich structure,it is challenging to avoid collapse of foam core at the trailing ***,an Equal Proportional Thickening(EPT)method is proposed to optimize the interference of polymethacrylimide(PMI)foam core during the CCM ***,based on some basic parameters of composite skin and foam core obtained by experiments or multi-scale simulations,a thermal-curing-mechanical coupling analysis for the CCM of foam sandwich structure is performed and the results show that the maximum stress within foam core occurs at the completion of mold-closing,which tends to decrease during the subsequent CCM ***,the foam core is thickened by traditional equidistant-thickening method,and the simulation reveals that the foam core at the trailing edge tends to collapse because of stress ***,if the foam core is thickened by the proposed EPT method,the mold-closing caused collapse at the trailing edge can be effectively avoided,and a thickening ratio range of 0.6%–2.0%is obtained,which is further proved by practical ***,the interference design scheme proposed can ensure the molding quality and effectively reduce the scrap of molded products.

关键词： Airfoil foam sandwich structure Polymethacrylimide(PMI)foam Interference Co-curing Molding simulation