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Phase field modeling of ferroelastic variant switching in yttria-stabilized t'zirconia with strain gradient elasticity and interface tension

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Science China(Technological Sciences) 2024年第5期67卷 1443-1457页

作者： ZHOU QianQian wei yueguang ZHOU YiChun YANG Li College of Engineering BIC-ESATPeking UniversityBeijing100871China School of Advanced Materials and Nanotechnology Xidian UniversityXi’an710126China Frontier Research Center of Thin Films and Coatings for Device Applications Academy of Advanced Interdisciplinary ResearchXidian UniversityXi’an710126China

The 6–8 wt%yttria-stabilized zirconia with a tetragonal structure(t’-YSZ)is extensively employed in thermal barrier *** exceptional fracture toughness of t’-YSZ can be attributed to its distinctive ferroelastic toughening *** and interface tension play a critical role in ferroelastic variant switching at the micro-and *** paper presents an original thermodynamically consistent phase field(PF)theory for analyzing ferroelastic variant switching at the micro-and nano-scale of t’-*** theory incorporates strain gradient elasticity using higher-order elastic energy and interface tension tensor via geometric nonlinearity to represent biaxial tension resulting from interface ***,a mixed-type formulation is employed to implement the higher-order theory through the finite element *** an interface in equilibrium,the effects of strain gradient elasticity result in a more uniform distribution of stresses,whereas the presence of interface tension tensor significantly amplifies the stress magnitude at the *** introduction of an interface tension tensor increases the maximum value of stress at the interface by a factor of 4 to *** nucleation and evolution of variants at a pre-existing crack tip in a mono-phase t’-YSZ have also been *** strain gradient elasticity is capable of capturing the size effect of ferroelastic variant switching associated with microstructures in ***,when the grain size approaches that of the specimen,the critical load required for variant switching at the crack tip increases,resulting in greater dissipation of elastic energy during ferroelastic variant ***,the interface tension accelerates the evolution of *** presented framework exhibits significant potential in modeling ferroelastic variant switching at the micro-and nano-scale.

关键词： thermodynamics strain gradient elasticity interface tension phase field method ferroelastic variant switching

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摩擦对力链中动态能量耗散的影响机制研究

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中国科学：物理学、力学、天文学 2024年第5期54卷 224-235页

作者：王志超彭青刘畅刘小明魏悦广中国科学院力学研究所非线性力学国家重点实验室北京100190 中国科学院大学工程科学学院北京100049 北京大学工学院北京100871

本文建立了一个两侧受到约束的有限长一维颗粒系统模型,探究了摩擦对颗粒材料耗能机制的影响.本文采用离散元方法研究该动力学过程中能量的耗散机理,模型中颗粒之间、颗粒和约束之间的法向接触采用非线性Hertz接触模型,切向接触采用Mind... 详细信息

本文建立了一个两侧受到约束的有限长一维颗粒系统模型,探究了摩擦对颗粒材料耗能机制的影响.本文采用离散元方法研究该动力学过程中能量的耗散机理,模型中颗粒之间、颗粒和约束之间的法向接触采用非线性Hertz接触模型,切向接触采用Mindlin剪切模型,通过分析主孤立波的幅值和波速以及颗粒间接触力的衰减规律探究颗粒材料能量耗散机制.结果表明:受到冲击的一维颗粒链中会产生一道主孤立波,孤立波的幅度在远小于颗粒间最大接触力的摩擦力作用下仍然会产生显著的衰减;摩擦力的存在使得系统中的动态能量会在有限深度内耗散;此耗散深度依赖于摩擦力的大小.根据能量传播路径上的耗散规律,将耗散过程可分为非线性接触主导过程、中间过程、摩擦和接触混合主导过程三个阶段,分别分析了每阶段相应的力学机制.

关键词：颗粒材料摩擦耗散冲击吸能非线性接触

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Trans-scale surface wrinkling model and scaling relationship analysis of stiff film-compliant substrate structures

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Science China(Technological Sciences) 2022年第11期65卷 2776-2786页

作者： LIU Yanwei ZHANG SiYuan LONG Hao wei yueguang Department of Mechanics and Enginering SCcience College of EngineeringBIC-ESATPeking UniversiyBeijing 100871China School of Mechanical Engineering University of Shanghai for SCcience and TechnologyShanghai 200093China

The self-assembly of surface-order structures based on the surface wrinkling of stiff film-compliant substrate structures(SFCS)is potentially useful in the fabrication of functional devices,the manufacture of superhydrophobic or self-cleaning surfaces,and so *** to the influence of the intrinsic characteristic length(g),the surface wrinkling behavior of SFCS at the micro scale is different from that at the macro *** this work,based on the strain gradient theory,a trans-scale surface wrinkling model for SFCS is ***,the effectiveness of this model is verified by previous ***,based on the model and dimensional analysis,the effect of g on the surface wrinkling behavior is investigated,and the scaling relationship of surface wrinkling of SFCS at different scales is *** results show that the influence of g cannot be neglected when the film thickness decreases to the one comparable to *** the micro scale,g will lead to the increase of the critical wrinkling wavelength and *** addition,the scaling relationship of surface wrinkling at the micro scale will not follow the traditional *** study explains the underlying mechanism of the dissimilarity of surface wrinkling behaviors of SFCS at different scales and lays a theoretical foundation for the precise control of surface-order structures.

关键词： stiff film-compliant substrate structures surface wrinkling trans-scale model dimensional analysis scaling relationship

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A chemo-thermo-mechanically constitutive theory of high-temperature interfacial oxidation in alloys under deformation

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Science China(Technological Sciences) 2023年第4期66卷 1018-1037页

作者： ZHOU QianQian YANG Li NIE Min ZHOU YiChun wei yueguang College of Engineering BIC-ESATPeking UniversityXi'an 710126China School of Advanced Materials and Nanotechnology Xidian UniversityBeijing 100871China Frontier Research Center of Thin Films and Coatings for Device Applications Academy of Advanced Interdisciplinary ResearchXidian UniversityXi'an 710126China AECC Hunan Aviation Powerplant Research Institute Zhuzhou 412002China

Failure due to interfacial oxidation is one of the most important factors in the failure of alloy systems at high *** analyze high-temperature interfacial oxidation in alloys under deformation,we develop a thermodynamically consistent continuum theory of alloy interfacial oxidation process considering diffusion,oxidation,expansion,viscoplasticity,and deformation *** equations of force,mass,and energy are presented at first,while the coupled constitutive laws and evolution equations are constructed according to energy dissipation *** coupled kinetics reveals a new mechanism whereby deformation affects the oxidation reaction by changing the alloy’s critical oxygen *** tensile loads decrease the critical oxygen concentration and promote oxidation of the ***,external compressive loads increase the critical oxygen concentration and suppress the oxidation of the ***,this theory is applied to thermal barrier coatings(TBCs),exhibiting a good consistency with the high-temperature oxidation experiment of TBCs under external *** model successfully explains that the experimental phenomenon of external tensile load accelerates the growth of Al_(2)O_(3)-TGO(thermally grown oxides).Besides,external compressive loads slow down the growth of Al_(2)O_(3)-TGO at the interface and lead to internal oxidation of the bond *** presented framework has shown great potential for modeling high-temperature interfacial oxidation processes in alloy systems under deformation.

关键词： thermodynamics oxidation oxygen diffusion chemo-thermo-mechanically coupling alloy

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Microstructure observation and mechanical behavior modeling for limnetic nacre

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Acta Mechanica Sinica 2008年第1期24卷 83-89页

作者： Shuchun Zuo yueguang wei LNM Institute of Mechanics Chinese Academy of Sciences 100080 Beijing China

In the present research, microstructure of akind of limnetic shell （Hyriopsis cumingii） is observed and measured by using the scanning electron microscopy, and mechanical behavior experiments of the shell nacre are carried out by using bending and tensile tests. The dependence of mechanical properties of the shell nacre on its microstructure is analyzed by using a modified shear-lag model, and the overall stress-strain relation is obtained. The experimental results reveal that the mechanical properties of shell nacre strongly depend on the water contents of the limnetic shell. Dry nacre shows a brittle behavior, whereas wetting nacre displays a strong ductility. Compared to the tensile test, the bending test overestimates the strength and underestimates the Young＇s modulus. The modified shear-lag model can characterize the deformation features of nacre effectively.

关键词： Nacre. Microstructure Shear-lag model .Mechanical property

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Inverse analysis determining interfacial properties between metal film and ceramic substrate with an adhesive layer

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Acta Mechanica Sinica 2008年第3期24卷 297-303页

作者： Haifeng Zhao yueguang wei State-Key Laboratory of Nonlinear Mechanics (LNM) Institute of Mechanics Chinese Academy of ScienceBeijing 100080 China

In the present study, peel tests and inverse analysis were performed to determine the interracial mechanical parameters for the metal film/ceramic system with an epoxy interface layer between film and ceramic. Al films with a series of thicknesses between 20 and 250 μm and three peel angles of 90°, 135° and 180° were considered. A finite element model with the cohesive zone elements was used to simulate the peeling process. The finite element results were taken as the training data of a neural network in the inverse analysis. The interracial cohesive energy and the separation strength can be determined based on the inverse analysis and peel experimental result

关键词： Thin film Peel test Interface toughness Cohesive zonemodel Inverse analysis

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A study of indentation scaling relationships of elastic-perfectly plastic solids with an inclusion near the conical indenter tip

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Science China(Technological Sciences) 2019年第5期62卷 721-728页

作者： YU ZhiJie wei yueguang Department of Mechanics and Engineering Science College of Engineering Peking University

Indentation hardness is found to be related to indentation depth when indentation test is applied on homogeneous materials under small indentation depth, which shows strong size effect in the indentation. While in contrast, indentation hardness has a very limited relationship with indentation depth when it is large, showing distinct scaling relationships between hardness and material properties. Previous studies on scaling relationships under deep indentation condition of elastic-perfectly plastic homogeneous materials have been carried out systematically by finite element analysis. In this paper, a heterogeneous material, particlereinforced matrix composite is detailed studied to investigate its scaling relationships under deep indentation with different particle positions and material properties by finite element analysis.

关键词： conical indentation elastic-perfect plastic grain composite scaling relationships

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Identifying the viscoelastic properties of soft matter from the indentation response of a hard film-soft substrate system

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Science China(Physics,Mechanics & Astronomy) 2020年第4期63卷 108-118页

作者： Yanwei Liu yueguang wei Hao Long Department of Mechanics and Engineering Science College of EngineeringPeking UniversityBeijing 100871China

The indentation technique is widely used in measuring the mechanical properties of soft matter at the microscale or nanoscale,but still faces challenges by these unique properties as well as the consequent strong surface adhesion, including the strong nonlinear effect, unclear judgment of the contact point, difficulties in estimating the contact area, and the risk of the indenter piercing the sample. Here we propose a two-step method to solve these problems: lay a hard film on a soft matter, and obtain the viscoelastic properties of this soft matter through the indentation response of this composite structure. We first establish a theoretical indentation model of the hard film-soft substrate system based on the theory of plates, elastic-viscoelastic correspondence principle and Boltzmann superposition principle. To verify the correctness of this method, we measure the mechanical properties of the methyl vinyl silicone rubber(MVSR) covered by a Cu nanofilm. Finally, we test the effectiveness and error sensitivity of this method with the finite element method(FEM). The results show that our method can accurately measure the mechanical properties of soft matter, while effectively circumventing the problems of the traditional indentation technique.

关键词： viscoelastic properties soft matter theoretical indentation model indentation technique finite element method

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SIMULATIONS OF MECHANICAL BEHAVIOR OF POLYCRYSTALLINE COPPER WITH NANO-TWINS

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Acta Mechanica Solida Sinica 2008年第3期21卷 189-197页

作者： Bo Wu yueguang wei State-Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China

Mechanical behavior and microstructure evolution of polycrystalline copper with nano-twins were investigated in the present work by finite element simulations. The fracture of grain boundaries are described by a cohesive interface constitutive model based on the strain gradient plasticity theory. A systematic study of the strength and ductility for different grain sizes and twin lamellae distributions is performed. The results show that the material strength and ductility strongly depend on the grain size and the distribution of twin lamellae microstructures in the polycrystalline copper.

关键词： nanocrystalline twinned copper mechanical behavior cohesive model finite element simulation

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EFFECTIVE ELASTIC MODULUS OF BONE-LIKE HIERARCHICAL MATERIALS

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Acta Mechanica Solida Sinica 2007年第3期20卷 198-205页

作者： Zuo Shuchun wei yueguang LNM Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

A shear-lag model is used to study the mechanical properties of bone-like hierarchical materials. The relationship between the overall effective modulus and the number of hierarchy level is obtained. The result is compared with that based on the tension-shear chain model and finite element simulation, respectively. It is shown that all three models can be used to describe the mechanical behavior of the hierarchical material when the number of hierarchy levels is small. By increasing the number of hierarchy level, the shear-lag result is consistent with the finite element result. However the tension-shear chain model leads to an opposite trend. The transition point position depends on the fraction of hard phase, aspect ratio and modulus ratio of hard phase to soft phase. Further discussion is performed on the flaw tolerance size and strength of hierarchical materials based on the shear-lag analysis.

关键词： hierarchical materials tension-shear chain model shear-lag model

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