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A procedure of the method of reverberation ray matrix for the buckling analysis of a thin multi-span plate

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Applied Mathematics and Mechanics(English Edition) 2020年第7期41卷 1055-1068页

作者： Zhiwei LI guohua nie School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai 200092China

A procedure of the method of reverberation ray matrix(MRRM)is developed to perform the buckling analysis of thin multi-span rectangular plates having internal line supports or stiffeners.A computation algorithm for the reverberation ray matrix in the MRRM is derived to determine the buckling ***,the analytical solutions are presented for the buckling of the structure having two opposite simply-supported or clamped-supported edges with spans,while the constraint condition of two remaining edges may be in any combination of free,simply-supported,and clamped boundary ***,based on the analysis of matrices relating to the unknown coefficients in the solution form for the deflection in terms of buckling modal functions,some recursive equations(REs)for the MRRM are introduced to generate a reduced reverberation ray matrix with unchanged dimension when the number of spans increases,which promotes the computation *** numerical examples are given,and the present results are compared with the known solutions to illustrate the validity and accurateness of the MRRM for the buckling analysis.

关键词： multi-span thin rectangular plate buckling method of reverberation ray matrix(MRRM) recursive equation(RE)

Method of reverberation ray matrix for static analysis of planar framed structures composed of anisotropic Timoshenko beam members

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Applied Mathematics and Mechanics(English Edition) 2015年第2期36卷 233-242页

作者： Jiao ZHANG guohua nie School of Aerospace Engineering and Applied Mechanics Tongji University

Based on the method of reverberation ray matrix（MRRM）, a reverberation matrix for planar framed structures composed of anisotropic Timoshenko（T） beam members containing completely hinged joints is developed for static analysis of such *** the MRRM for dynamic analysis, amplitudes of arriving and departing waves for joints are chosen as unknown quantities. However, for the present case of static analysis, displacements and rotational angles at the ends of each beam member are directly considered as unknown quantities. The expressions for stiffness matrices for anisotropic beam members are developed. A corresponding reverberation matrix is derived analytically for exact and unified determination on the displacements and internal forces at both ends of each member and arbitrary cross sectional locations in the structure. Numerical examples are given and compared with the finite element method（FEM） results to validate the present model. The characteristic parameter analysis is performed to demonstrate accuracy of the present model with the T beam theory in contrast with errors in the usual model based on the Euler-Bernoulli（EB） beam theory. The resulting reverberation matrix can be used for exact calculation of anisotropic framed structures as well as for parameter analysis of geometrical and material properties of the framed structures.

关键词： planar framed structure anisotropic Timenshenko(T) beam stiffness matrix method of reverberation ray matrix(MRRM) static analysis

Nonlinear free vibration of reticulated shallow spherical shells taking into account transverse shear deformation

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Applied Mathematics and Mechanics(English Edition) 2018年第12期39卷 1825-1836页

作者： Rong WANG guohua nie School of Aerospace Engineering and Applied Mechanics Tongji University

This paper deals with nonlinear free vibration of reticulated shallow spherical shells taking into account the effect of transverse shear deformation. The shell is formed by beam members placed in two orthogonal directions. The nondimensional fundamental governing equations in terms of the deflection, rotational angle, and force function are presented, and the solution for the nonlinear free frequency is derived by using the asymptotic iteration method. The asymptotic solution can be used readily to perform the parameter analysis of such space structures with numerous geometrical and material parameters. Numerical examples are given to illustrate the characteristic amplitudefrequency relation and softening and hardening nonlinear behaviors as well as the effect of transverse shear on the linear and nonlinear frequencies of reticulated shells and plates.

关键词： nonlinear free vibration reticulated shallow spherical shell transverse shear effect asymptotical iteration method amplitude-frequency relation

Dynamic quasi-continuum model for plate-type nano-materials and analysis of fundamental frequency

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Applied Mathematics and Mechanics(English Edition) 2021年第1期42卷 85-94页

作者： Chunxiao XIA Wenlong XU guohua nie School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai 200092China

A dynamic quasi-continuum model is presented to analyze free vibration of plate-type cubic crystal *** to the Hamilton principle,fundamental governing equations in terms of displacement components and angles of rotations are *** an application of the model,the cylindrical bending deformation of the structure fixed at two ends is analyzed,and a theoretical formula evaluating the fundamental frequency is obtained by using Galerkin's ***,the solution for the classical continuous plate model is also derived,and the size-dependent elastic modulus and Poisson's ratio are taken in *** frequencies corresponding to different atomic layers are numerically presented for the plate-type NaC l ***,a molecular dynamics(MD)simulation is conducted with the code *** comparison shows that the present quasi-continuum model is valid,and it may be used as an alternative model,which reflects scale effects in analyzing dynamic behaviors of such plate-type nano-materials.

关键词： plate-type nano-material quasi-continuum model size-dependent fundamental frequency theoretical solution molecular dynamics(MD)simulation

Nonlinear analysis of imperfect squarely-reticulated shallow spherical shells

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Science China(Physics,Mechanics & Astronomy) 2007年第1期50卷 109-117页

作者： nie guohua LI ZhiWei Institute of Applied Mechanics School of Aerospace Engineering and Applied MechanicsTongji UniversityShanghai 200092China

Nonlinear behavior of single-layer squarely-reticulated shallow spherical shells with geometrical imperfections subjected to a central concentrated (joint) load has been studied in this paper. Using the asymptotic iteration method, an analytical characteristic relationship between the non-dimensional load and central deflection is obtained. The resulting asymptotic solution can be used readily to perform the analysis of parameters and predict the buckling critical load. Meanwhile, numerical examples are presented and effects of imperfection factor and boundary conditions on buckling of the structures are discussed. Comparisons with data based on the finite element method show good exactness of the resulting solution.

关键词： shallow spherical shell squarely-reticulated geometrical imperfection concentrated load nonlinear buckling asymptotic iteration method

Elastic fields induced by non-elastic eigenstrains in a plane elliptical inhomogeneity existing in orthotropic media under uniform tension at infinity

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Science China(Physics,Mechanics & Astronomy) 2008年第2期51卷 206-218页

作者： GUO Lei nie guohua Institute of Applied Mechanics School of Aerospace Engineering and Applied MechanicsTongji UniversityShanghai 200092China

This paper presents an analytical solution for the elastic fields induced by non-elastic eigenstrains in a plane elliptical inhomogeneity embedded in the orthotropic matrix under tension at infinity and inclined at any angle. The conformal transformation and complex function method for the anisotropic elastic material were used to determine the strain energies in the inhomogeneity and matrix, which were expressed by four undetermined coefficients characterizing the equilibrium boundary of the inhomogeneity due to the acting eigenstrains and external load. The use of the principle of the minimum potential energy led to analytical expres-sions for these coefficients and thus generated a closed-form solution for the elas-tic strain/stress fields. The resulting stress field in the inhomogeneity was exam-ined and verified by checking the continuity conditions for the normal and shear stresses on the interior boundary of the matrix.

关键词： complex function method conformal transformation orthotropic elliptical inhomogeneity tension non-ela-stic eigenstrains

Nonlinear Bending of FCC Nanoplates Based on a Quasi-Continuum Model

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Acta Mechanica Solida Sinica 2022年第6期35卷 1030-1039页

作者： Wenjing Zhan Yaqi Guo Ying Zhao guohua nie School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai200092China

A quasi-continuum model of plate-type nanomaterials with the face-centered cubic crystal structures is proposed in this *** fundamental governing equations for the nonlinear bending of the nanoplates are given by using the principle of minimum potential ***,the analytical solution is derived for cylindrical bending deformation of the structure under uniform transverse loading fixed at two sides based on the modified iterative method.A lattice finite element model is established to verify the present quasi-continuum ***,the corresponding solution by adopting the classical continuous plate theory is presented,in which two cases are considered for use of bulk values(limit values)and nanovalues of both elastic modulus and Poisson's *** difference among the quasi-continuum and continuous models are discussed by computation.

关键词： FCC Nanoplates Quasi-continuum model Size effect Nonlinear bending

The Motion Trace of Particles in Classifying Flow Field

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Journal of Wuhan University of Technology(Materials Science) 2005年第2期20卷 71-73页

作者：黎国华 School of Mineral Resources and Environmental Protection Engineering Wuhan University of TechnologyWuhan 430070China Assoc.Prof

According to the theory of the stochastic trajectory model of particle in the gas-solid two-phase flows, the two-phase turbulence model between the blades in the inner cavity of the FW-Φ150 horizontal turbo classifier was established, and the commonly-used PHOENICS code was adopted to carried out the numerical simulation. It was achieved the flow characteristics under a certain condition as well as the motion trace of particles with different diameters entering from certain initial location and passing through the flow field between the blades under the correspondent condition. This research method quite directly demonstrates the motion of particles. An experiment was executed to prove the accuracy of the results of numerical simulation.

关键词： stochastic trajectory model turbo classifier numerical simulation motion trace

Stretchable,Rehealable,Recyclable,and Reconfigurable Integrated Strain Sensor for Joint Motion and Respiration Monitoring

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Research 2021年第1期2021卷 1305-1318页

作者： Chuanqian Shi Zhanan Zou Zepeng Lei Pengcheng Zhu guohua nie Wei Zhang Jianliang Xiao Department of Mechanical Engineering University of Colorado BoulderBoulderColorado 80309USA School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai 200092China Department of Chemistry University of Colorado BoulderBoulderColorado 80309USA School of Materials Science and Engineering Beihang UniversityBeijing 100191China

Cutting-edge technologies of stretchable,skin-mountable,and wearable electronics have attracted tremendous attention recently due to their very wide applications and promising *** direction of particular interest is to investigate novel properties in stretchable electronics by exploring multifunctional ***,we report an integrated strain sensing system that is highly stretchable,rehealable,fully recyclable,and *** system consists of dynamic covalent thermoset polyimine as the moldable substrate and encapsulation,eutectic liquid metal alloy as the strain sensing unit and interconnects,and off-the-shelf chip components for measuring and magnifying *** device can be attached on different parts of the human body for accurately monitoring joint motion and *** a strain sensing system provides a reliable,economical,and ecofriendly solution to wearable technologies,with wide applications in health care,prosthetics,robotics,and biomedical devices.

关键词： wear alloy eutectic