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Acta Mechanica Sinica 2015年第5期31卷 601-626页

作者： wei-qiu Chen Department of Engineering Mechanics Zhejiang University

Significant progress has been made in mixed boundary-value problems associated with three-dimensional（3D） crack and contact analyses of advanced materials featuring more complexities compared to the conventional isotropic elastic *** include material anisotropy and multifield coupling,two typical characteristics of most current multifunctional *** this paper we try to present a state-of-the-art description of 3D exact/analytical solutions derived for crack and contact problems of elastic solids with both transverse isotropy and multifield coupling in the latest decade by the potential theory method in the spirit of *** ingenious breakthrough brings new vigor and vitality to the old research subject of classical potential *** are particularly interested in crack and contact problems with certain nonlinear *** is also placed on the coupling between the temperature field（or the like） and other physical fields（e.g.,elastic,electric,and magnetic fields）.We further highlight the practical significance of 3D contact solutions,in particular in applications related to modern scanning probe microscopes.

关键词： Crack Contact Mixed boundary-value problem Transverse isotropy Multifield coupling Potential theory Exact solution Scanning probe microscope

Neutronic analysis of deuteron-driven spallation target

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Nuclear Science and Techniques 2021年第9期32卷 52-60页

作者： wei-wei qiu Wu Sun Jun Su Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China

Deuteron-driven spallation targets have garnered attention recently because they can provide high-energy neutrons to transmute long-lifetime fission *** this study,the Geant4 toolkit was used to simulate the inter-action between a deuteron beam at 500 MeV and a com-posite target composed of alternating lead-bismuth eutectic(LBE)and *** water was used because it may be employed as a target *** energy spectrum,neu-tron yield,average energy,and total energy of the emitted neutrons were calculated for different thicknesses and thickness ratios between the LBE and *** a constant target thickness,the neutron yield increases with an increasing thickness ratio of LBE to H 2 O,while the aver-age energy of the emitted neutrons decreases with an increasing in the aforementioned thickness *** two aspects support the use of a pure target,either LBE or ***,with an increasing LBE-to-H 2 O thickness ratio,the total energy of the emitted neutrons increases and then *** result supports the addition of water into the LBE *** angular distributions of the emitted neutrons show that the rear of the target is suit-able for loading nuclear waste containing minor actinides and long-lifetime fission products.

关键词： Long-lived nuclear waste product Accelerator-driven sub-critical system Deuteron-induced spallation target Neutron spectrum

Stochastic optimal control of cable vibration in plane by using axial support motion

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Acta Mechanica Sinica 2011年第4期27卷 578-586页

作者： Ming Zhao wei-qiu Zhu Department of Mechanics State Key Laboratory of Fluid Power Transmission and Control Zhejiang University 310027 Hangzhou China

A stochastic optimal control strategy for a slightly sagged cable using support motion in the cable axial direction is proposed. The nonlinear equation of cable motion in plane is derived and reduced to the equations for the first two modes of cable vibration by using the Galerkin method. The partially averaged Ito equation for controlled system energy is further derived by applying the stochastic averaging method for quasi-non-integrable Hamiltonian systems. The dynamical programming equation for the controlled system energy with a performance index is established by applying the stochastic dynamical programming principle and a stochastic optimal control law is obtained through solving the dynamical programming equation. A bilinear controller by using the direct method of Lyapunov is introduced. The comparison between the two controllers shows that the proposed stochastic optimal control strategy is superior to the bilinear control strategy in terms of higher control effectiveness and efficiency.

关键词： Stay cable Active control - Stochastic optimalcontrol Dynamical programming principle

Analysis of the penalty version of the Arlequin framework for the prediction of structural responses with large deformations

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第7期12卷 552-560页

作者： Hua QIAO wei-qiu CHEN Department of Engineering Mechanics Zhejiang University Hangzhou 310027 China

The Arlequin framework proposed by Ben Dhia in 1998 is a flexible and robust method for conducting global/local analysis of structures and materials.A penalty version of the Arlequin framework for the study of structural problems involving large deformation is considered *** implementation of the penalty-based Arlequin framework into ABAQUS is then explored and the corresponding Arlequin user element subroutine is *** nonlinear simulations of a cantilever beam and a shallow arch are conducted and the choice of the coupling operator with an appropriate penalty parameter is *** numerical results justify the feasibility of the proposed method,ensuring its further application to more complicated problems involving geometric or material nonlinearities.

关键词： Global/Local analysis Geometric nonlinear analysis Penalty-based Arlequin method User defined element

Science Letters:On numerical calculation in symplectic approach for elasticity problems

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第5期9卷 583-588页

作者： Li ZHAO wei-qiu CHEN Department of Civil Engineering Zhejiang University Hangzhou 310027 China

The symplectic approach proposed and developed by Zhong et al. in 1990s for elasticity problems is a rational analytical method, in which ample experience is not needed as in the conventional semi-inverse method. In the symplectic space, elasticity problems can be solved using the method of separation of variables along with the eigenfunction expansion technique, as in traditional Fourier analysis. The eigensolutions include those corresponding to zero and nonzero eigenvalues. The latter group can be further divided into α-and β-sets. This paper reformulates the form of β-set eigensolutions to achieve the stability of numerical calculation, which is very important to obtain accurate results within the symplectic frame. An example is finally given and numerical results are compared and discussed.

关键词： Symplectic approach Eigenfunction Numerical stability Elasticity problems

Response of harmonically and stochastically excited strongly nonlinear oscillators with delayed feedback bang-bang control

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第1期10卷 54-61页

作者： Chang-shui FENG wei-qiu ZHU Institute of Mechatronic Engineering Hangzhou Dianzi University Hangzhou 310018 China State Key Laboratory of Fluid Power Transmission and Control Department of Mechanics Zhejiang University Hangzhou 310027 China

We studied the response of harmonically and stochastically excited strongly nonlinear oscillators with delayed feedback bang-bang control using the stochastic averaging method. First, the time-delayed feedback bang-bang control force is expressed approximately in terms of the system state variables without time delay. Then the averaged It6 stochastic differential equations for the system are derived using the stochastic averaging method. Finally, the response of the system is obtained by solving the Fokker-Plank-Kolmogorov （FPK） equation associated with the averaged lt6 equations. A Duffing oscillator with time-delayed feedback bang-bang control under combined harmonic and white noise excitations is taken as an example to illus- trate the proposed method. The analytical results are confirmed by digital simulation. We found that the time delay in feedback bang-bang control will deteriorate the control effectiveness and cause bifurcation of stochastic jump of Duffing oscillator.

关键词： Nonlinear system Delayed feedback bang-bang control Combined harmonic and white noise excitation Stochastic averaging Stationary response Stochastic jump

3D analytical solution for a rotating transversely isotropic annular plate of functionally graded materials

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第7期8卷 1038-1043页

作者： CHEN Jiang-ying CHEN wei-qiu Faculty of Engineering Ningbo University Ningbo 315211 China Department of Civil Engineering Zhejiang University Hangzhou 310027 China

The analytical solution for an annular plate rotating at a constant angular velocity is derived by means of direct displacement method from the elasticity equations for axisymmetric problems of functionally graded transversely isotropic media. The displacement components are assumed as a linear combination of certain explicit functions of the radial coordinate, with seven undetermined coefficients being functions of the axial coordinate z. Seven equations governing these z-dependent functions are derived and solved by a progressive integrating scheme. The present solution can be degenerated into the solution of a rotating isotropic functionally graded annular plate. The solution also can be degenerated into that for transversely isotropic or isotropic homogeneous materials. Finally, a special case is considered and the effect of the material gradient index on the elastic field is illustrated numerically.

关键词： Functionally graded materials Transversely isotropic Rotating annular plate Analytical solution

DYNAMIC CHARACTERISTICS OF LARGE FLOW RATING ELECTROHYDRAULIC PROPORTIONAL CARTRIDGE VALVE

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Chinese Journal of Mechanical Engineering 2008年第6期21卷 57-62页

作者： FU Linjian wei Jianhua qiu Minxiu State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

A kind of cartridge servo proportional valve is discussed, which can be used for controlling large flow rate with high performance. By analyzing the structure principle of the valve, the transfer fimction of the valve is derived. With the transfer function, some structure elements that may affect its performance are investigated. Through the numerical simulation and test study, some principles of optimality and effective methods for improving the dynamic performance of the valve are proposed. The test results conform to the results of the theoretical analysis and simulation, which proves the correctness of the study and simulation works. The paper provides theoretical basis for engineering applications and series expanding design works

关键词： Large flow rate electro-hydraulic proportional cartridge valve Dynamic characteristics

On the stochastic dynamics of molecular conformation

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第9期8卷 1401-1407页

作者： DENG Mao-lin ZHU wei-qiu Department of Mechanics State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

An important functioning mechanism of biological macromolecules is the transition between different conformed states due to thermal fluctuation. In the present paper, a biological macromolecule is modeled as two strands with side chains facing each other, and its stochastic dynamics including the statistics of stationary motion and the statistics of conformational transition is studied by using the stochastic averaging method for quasi Hamikonian systems. The theoretical results are confirmed with the results from Monte Carlo simulation.

关键词： Biological macromolecule Thermal fluctuation Stationary statistics Transition time Stochastic averaging method

Dynamics of a prey-predator system under Poisson white noise excitation

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Acta Mechanica Sinica 2014年第5期30卷 739-745页

作者： Shan-Shan Pan wei-qiu Zhu Department of Mechanics State Key Lab of Fluid Power Transmission and ControlZhejiang University

The classical Lotka-Volterra （LV） model is a well-known mathematical model for prey-predator ecosystems. In the present paper, the pulse-type version of stochastic LV model, in which the effect of a random natural environment has been modeled as Poisson white noise, is in- vestigated by using the stochastic averaging method. The averaged generalized It6 stochastic differential equation and Fokkerlanck-Kolmogorov （FPK） equation are derived for prey-predator ecosystem driven by Poisson white noise. Approximate stationary solution for the averaged generalized FPK equation is obtained by using the perturbation method. The effect of prey self-competition parameter e2s on ecosystem behavior is evaluated. The analytical result is confirmed by corresponding Monte Carlo （MC） simulation.

关键词： Prey-predator ecosystem Poisson white noise Stochastic averaging- Approximate stationary solution. Per turbation method