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ANALYSIS OF THE CHAOTIC MOTION FOR A ROTOR SYSTEM WITH A TRANSVERSE CRACK

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Acta Mechanica Solida Sinica 2003年第1期16卷 74-80页

作者： fu yiming zheng yufang Zhu Shijian Department of Engineering Mechanics Hunan UniversityChangsha 410082China Institute of Noise and Vibration University of Naval EngineeringWuhan 430033China

The chaotic motion of an elastic shaft-disk rotor system including thegeometric nonlinearity of the shaft with a transverse crack is investigated. The critical conditionfor the system to enter chaotic state is given by the Melnikov method. Meanwhile, whether the chaosoccurs is determined by the Poincare map, phase portrait and time-displacement history diagram.

关键词： geometric nonlinearity cracked rotor chaos

Analysis of energy release rate for composite delaminated cylindrical shells subjected to axial compression

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Acta Mechanica Sinica 2006年第6期22卷 537-546页

作者： Jinhua Yang yiming fu Department of Engineering Mechanics Hunan University Changsha 410082 China

In this paper, the postbuckling governing equations and the analytical expression of the energy release rates associated with delamination growth in a compression-loaded cylindrical shell are derived by using the variational principle of moving boundary and the Griffith fracture criterion. The finite difference method is used to generate the postbuckling solutions of the delaminated cylindrical shells, and with these solutions, the values of the energy release rates are determined. In simulational examples, the effects of a wide range of parameters, such as delamination sizes and depths, boundary conditions, geometrical parameters, material properties and laminate stacking sequences on the energy release rates of axisymmetrical laminated cylindrical shells are intensively discussed.

关键词： Composite cylindrical shell Delamination Griffith criterion Energy release rates Finite difference method

Organosilicon polymer-derived ceramics: An overview

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Journal of Advanced Ceramics 2019年第4期8卷 457-478页

作者： Shengyang fu Min ZHU yufang ZHU School of Materials Science and Engineering University of Shanghai for Science and Technology

Polymer-derived ceramics(PDCs) strategy shows a great deal of advantages for the fabrication of advanced ceramics. Organosilicon polymers facilitate the shaping process and different silicon-based ceramics with controllable components can be fabricated by modifying organosilicon polymers or adding fillers. It is worth noting that silicate ceramics can also be fabricated from organosilicon polymers by the introduction of active fillers, which could react with the produced silica during pyrolysis. The organosilicon polymer-derived ceramics show many unique properties, which have attracted many attentions in various fields. This review summarizes the typical organosilicon polymers and the processing of organosilicon polymers to fabricate silicon-based ceramics, especially highlights the three-dimensional(3 D) printing technique for shaping the organosilicon polymerderived ceramics, which makes the possibility to fabricate silicon-based ceramics with complex structure. More importantly, the recent studies on fabricating typical non-oxide and silicate ceramics derived from organosilicon polymers and their biomedical applications are highlighted.

关键词： polymer-derived ceramics(PDCs) organosilicon polymers 3D printing silicon-based ceramics

A continuum damage model for piezoelectric materials

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Acta Mechanica Sinica 2008年第2期24卷 171-179页

作者： yiming fu X. Wang College of Mechanics and Aerospace Hunan University Changsha 410082 China

In this paper, a constitutive model is proposed for piezoelectric material solids containing distributed cracks. The model is formulated in a framework of continuum damage mechanics using second rank tensors as internal variables. The Helrnhotlz free energy of piezoelectric mate- rials with damage is then expressed as a polynomial including the transformed strains, the electric field vector and the tensorial damage variables by using the integrity bases restricted by the initial orthotropic symmetry of the material. By using the Talreja＇s tensor valued internal state damage variables as well as the Helrnhotlz free energy of the piezoelectric material, the constitutive relations of piezoelectric materials with damage are derived. The model is applied to a special case of piezoelectric plate with transverse matrix cracks. With the Kirchhoff hypothesis of plate, the free vibration equations of the piezoelectric rectangular plate considering damage is established. By using Galerkin method, the equations are solved. Numerical results show the effect of the damage on the free vibration of the piezoelectric plate under the close-circuit condition, and the present results are compared with those of the three-dimensional theory.

关键词： Tensor valued internal state variables Continuum damage mechanics Damage constitutiverelations Piezoelectric plate

Stochastic response analysis of damaged elastic beams

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Science China(Technological Sciences) 2012年第6期55卷 1618-1623页

作者： TIAN YanPing fu yiming School of Mechanical Engineering Hangzhou Dianzi UniversityHangzhou 310018China College of Mechanical and Vehicle Engineering Hunan UniversityChangsha 410082China

Great progress has been made in study on dynamic behavior of the damaged structures subject to deterministic *** stochastic response analysis of the damaged structures,however,has not yet attracted people's *** the damaged elastic beams for example,the analysis procedure for stochastic response of the damaged structures subject to stochastic excitations is investigated in this ***,the damage constitutive relations and the corresponding damage evolution equation of one-dimensional elastic structures are briefly ***,the stochastic dynamic equation with respect to transverse displacement of the damaged elastic beams is *** finite difference method and Newmark method are adopted to solve the stochastic partially-differential equation and corresponding boundary *** stochastic response characteristic,damage evolution law,the effect of noise intensity on damage evolution and the first-passage time of damage are discussed in *** present work extends the research field of damaged structures,and the proposed procedure can be generalized to analyze the dynamic behavior of more complex structures,such as damaged plates and shells.

关键词： damaged elastic beams stochastic response Gaussian white noise first-passage time of damage finite differencemethod

ANALYSIS OF ELASTO-PLASTIC POSTBUCKLING AND ENERGY RELEASE RATE FOR DELAMINATED FIBER METAL LAMINATED BEAMS IN THERMAL ENVIRONMENT

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Acta Mechanica Solida Sinica 2015年第6期28卷 693-705页

作者： yiming fu Yang Chen Xuefei Shao State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University College of Mechanical and Vehicle Engineering Hunan University

The elasto-plastic postbuckling of fiber metal laminated beams with delamination and the energy release rate along the delamination front are discussed in this paper. Considering geometrical nonlinearity, thermal environment and geometrical initial imperfection, the incremental nonlinear equilibrium equations of delaminated fiber metal laminated beams are established, which are solved using the differential quadrature method and iterative method. Based on these, according to the J-integral theory, the elasto-plastic energy release rate is studied. The effects of some important parameters on the elasto-plastic postbuckling behavior and energy release rate of the aramid reinforced aluminum laminated beams are discussed in details.

关键词： fiber metal laminated beams delamination temperature effect elasto-plastic post- buckling elasto-plastic energy release rate

Quadratic Stabilization of Switched Uncertain Linear Systems: A Convex Combination Approach

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IEEE/CAA Journal of Automatica Sinica 2019年第5期6卷 1116-1126页

作者： yufang Chang Guisheng Zhai Bo fu Lianglin Xiong the School of Electrical and Electronic Engineering Hubei University of TechnologyWuhan 430068China the Department of Mathematical Sciences Shibaura Institute of TechnologySaitama 337-8570Japan the School of Mathematics and Computer Science Yunnan Minzu UniversityKunming 650500China

We consider quadratic stabilization for a class of switched systems which are composed of a finite set of continuoustime linear subsystems with norm bounded uncertainties. Under the assumption that there is no single quadratically stable subsystem, if a convex combination of subsystems is quadratically stable, then we propose a state-dependent switching law, based on the convex combination of subsystems, such that the entire switched linear system is quadratically stable. When the state information is not available, we extend the discussion to designing an outputdependent switching law by constructing a robust Luenberger observer for each subsystem.

关键词： Convex combination limear matrix inequalities (LMIs) norm bounded uncertainties output-dependent switching, quadratic stabilization state-dependent switching switched uncertain linear systems(SULS)

NONLINEAR TRANSIENT RESPONSE OF fuNCTIONALLY GRADED SHALLOW SPHERICAL SHELLS SUBJECTED TO MECHANICAL LOAD AND UNSTEADY TEMPERATURE FIELD

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Acta Mechanica Solida Sinica 2014年第5期27卷 496-508页

作者： yiming fu Sumin Hu Yiqi Mao College of Mechanical and Vehicle Engineering Hunan University

This paper is concerned with the transient deformation of functionally graded （FG） shallow spherical shells subjected to time-dependent thermomechanical load. Based on Timoshenko- Mindlin hypothesis and yon Karman nonlinear theory, a set of nonlinear governing equations of motion for FG shallow spherical shells in regard to transverse shear deformation and all the inertia terms are established using Hamilton＇s principle. The collocation point method and Newmark- beta scheme in conjunction with the finite difference method are adopted to solve the governing equations of motion and the unsteady heat conduction equation numerically. In the numerical examples, the transient deflection and stresses of FG shallow spherical shells with various material properties under different loading conditions are presented.

关键词： functionally graded materials unsteady temperature field transient deflection andstresses

NONLINEAR VIBRATION OF BEAMPLATES WITH A DELAMINATION

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Acta Mechanica Solida Sinica 2000年第4期13卷 353-362页

作者： fu yiming Zhang Yunliang Hunan Univ Dept Engn Mech Changsha 410082 Peoples R China

The problem of beam-plates with a delamination located at anarbitrary site undergoing non- linear free vibration without damp isinvestigated. For this problem, nonlinear governing equations as wellas the continuity, equilibrium and compatibility conditions areestablished. The Galerkin method and harmonic balance method areemployed to find solutions. Finally, in some examples,amplitude-frequency curves of the delaminated structure are presentedin order to reveal some special dynamic features.

关键词： delamination beam-plate nonlinear vibration