Zhang Chunyu

Bio: Zhang Chunyu is an academic researcher from Harbin Engineering University. The author has contributed to research in topics: Vibration & Boundary value problem. The author has an hindex of 2, co-authored 4 publications receiving 43 citations.

Vibration analysis method of passive constrained damping rotating body structure

Abstract: The invention aims to provide a vibration analysis method of a passive constrained damping rotating body structure. The boundary condition information of the passive constrained damping rotating body structure is extracted; the passive constrained damping rotating body structure consists of two parts including a soft structure and a hard structure, wherein the soft structure is a middle damping layer, and the hard structure consists of an inner substrate, an outer substrate and a constrained layer; the soft structure and the hard structure are connected in a displacement way by an interlayer continuity condition; according to a first order shear deformation theory, relationship between middle surface strain and curvature and the relationship between the middle surface strain and displacement in the soft structure and the hard structure are independently determined, the total energy of the passive constrained damping rotating body structure is determined, a solver is established according to a Rayleigh-Ritz principle for solving, and the inherent frequency and the loss factor of the structure are output. The method can be used for solving a vibration problem and a damping analysis problem of the passive constrained damping rotating body structure under various complex boundary conditions including various classical boundary conditions, general elastic boundary conditions and non-uniform constraint boundary conditions.

Acoustic coupling method of coupling acoustic fields

Abstract: The invention discloses an acoustic coupling method of coupling acoustic fields. The method comprises setting a coupling interface impedance of two coupling acoustic fields, selecting a sound pressure function of each acoustic field, determining a Lagrange functional of each acoustic field according to a variational method, determining coupling energy of the two coupling acoustic fields, determining a coupling rigidity matrix of a coupling acoustic space coupling interface and a rigidity matrix corresponding to each acoustic field and a quality matrix corresponding to each acoustic matrix, performing combinations according to the rigidity matrixes of the two acoustic fields, the quality matrixes of the two acoustic fields and the coupling rigidity matrix, determining a coupling acoustic field characteristic equation, and obtaining coupling acoustic field acoustic forecast information. The acoustic coupling method has the advantages of rapid convergence of a forecast information and less resources needed by calculation.

Vibration analysis method for three-dimensional coupled structure

Abstract: The invention discloses a vibration analysis method for a three-dimensional coupled structure. The method comprises the steps that a coupled plate is divided into sub-unit plate structures; a displacement field function of the coupled plate structures is decomposed, and in-plane and out-plane displacement vectors and in-plane and out-plane external force vectors are calculated in combination withboundary conditions; mapping of in-plane and out-plane boundary displacement and force on a boundary is calculated; an in-plane dynamic stiffness matrix and an out-plane dynamic stiffness matrix are calculated; the dynamic stiffness matrixes are combined, and an in-plane and out-plane dynamic stiffness matrix is calculated; a dynamic stiffness matrix and a kinematical equation of the sub-unit plate structures are obtained through integration; a Cartesian coordinate system, where one of sub-units is located, is selected to serve as a global coordinate system, the dynamic stiffness matrix is converted to be under the global coordinate system, and then matrix assembling is performed to obtain an integral dynamic control equation of the structures; and the integral dynamic control equation ofthe structures is solved to obtain a forced vibration response of the three-dimensional coupled structure. Through the method, the forced vibration problem of a three-dimensional coupled shell with any classic boundary and any coupling angle can be solved.

A unified solution for vibration analysis of functionally graded circular, annular and sector plates with general boundary conditions

Abstract: The vibrations of functionally graded circular plates, annular plates, and annular, circular sectorial plates have been traditionally treated as different boundary value problems, which results in numerous specific solution algorithms and procedures. It is the problem itself that has been an overwhelming task for a new researcher or application engineer to comprehend. Furthermore each type of plate usually needs treating separately when different boundary conditions are involved. In this paper, a unified method is presented for the vibration analysis of the plates mentioned above with general boundary conditions based on the first-order shear deformation theory and Ritz procedure. The material properties are assumed to vary continuously through the thickness according to the general four-parameter power-law distribution. Regardless of the shapes of the plates and the types of boundary conditions, the displacements of the plates are described as an improved Fourier series expansion which is composed of a double Fourier cosine series and several auxiliary functions. As an innovative point of this work, the auxiliary functions are introduced to eliminate all the relevant discontinuities with the displacement and its derivatives at the boundaries and to accelerate the convergence of series representations. The accuracy, reliability and versatility of the current solution are fully demonstrated and verified through numerical examples involving plates with various shapes and boundary conditions. Some new results of functionally graded circular, annular and sector plates with various boundary conditions are presented, which may serve as datum solutions for future computational methods. In addition, the influence of boundary conditions, the material and geometric parameters on the vibration characteristics of the plates are also reported.

Nonlinear vibration analysis of fiber reinforced composite cylindrical shells with partial constrained layer damping treatment

Abstract: This research proposes a novel analytical model capable of accurately predicting the strain-dependent characteristics of fiber reinforced composite shells (FRCSs) with partial constrained layer damping (CLD) treatment by considering the nonlinearities of fiber reinforced composite and viscoelastic materials simultaneously. The nonlinear material properties are represented based on Jones-Nelson nonlinear theory, energy-based strain energy method, and complex modulus method. Then, the governing equations of motion for FRCSs are developed via Ritz method, and the identification procedure of nonlinear fitting parameters is also presented. By taking a T300 carbon fiber/epoxy resin cylindrical shell with partial CLD patches as an example, a series of experiments are carried out to validate the proposed modeling approach. Finally, the effects of material properties on nonlinear vibration behaviors of FRCSs covered with partial CLD patches are evaluated. Comparisons show that the proposed nonlinear model is more accuracy than that without considering strain dependence, where the maximum errors between the proposed model and measured data for natural frequencies, damping ratios and resonant response are 6.9%, 11.3%, and 11.2%, respectively.

Free vibration study of multilayer sandwich spherical shell panels with viscoelastic core and isotropic/laminated face layers

Abstract: The present work deals with the free vibration and damping characteristics study of multilayer sandwich spherical shell panels with viscoelastic material core layers and elastic face layers based on first order shear deformation theory. The displacements of the core layers are assumed to vary linearly along the thickness. Longitudinal and transverse deformations of the core layers are taken in to account with the consideration of independent transverse displacements of the elastic layers. The equation of motion is derived using Hamilton's principle in conjunction with the finite element method. Eight number of sandwich shell panels are studied mainly in two groups viz. sandwich panels with laminated base layer and isotropic base layer. Fundamental frequencies and associated system loss factors of different sandwich shell panels are deduced by solving the equation as an eigenvalue problem. The effect of thickness of the constraining layers, thickness of the core layers, viscoelastic material loss factor and aspect ratio on the natural frequencies and system loss factors of the sandwich structures are investigated.