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Li R.,State Key Laboratory of Structural Analysis for Industrial Equipment | Zhong Y.,Dalian University of Technology | Li M.,State Key Laboratory of Structural Analysis for Industrial Equipment
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2013

Analytic bending solutions of free rectangular thin plates resting on elastic foundations, based on the Winkler model, are obtained by a new symplectic superposition method. The proposed method offers a rational elegant approach to solve the problem analytically, which was believed to be difficult to attain. By way of a rigorous but simple derivation, the governing differential equations for rectangular thin plates on elastic foundations are transferred into Hamilton canonical equations. The symplectic geometry method is then introduced to obtain analytic solutions of the plates with all edges slidingly supported, followed by the application of superposition, which yields the resultant solutions of the plates with all edges free on elastic foundations. The proposed method is capable of solving plates on elastic foundations with any other combinations of boundary conditions. Comprehensive numerical results validate the solutions by comparison with those obtained by the finite element method. Copyright © The Royal Society 2013.


Li S.-J.,State Key Laboratory of Structural Analysis for Industrial Equipment | Shao L.-T.,State Key Laboratory of Structural Analysis for Industrial Equipment | Wang J.-Z.,Dalian Medical University | Liu Y.-X.,State Key Laboratory of Structural Analysis for Industrial Equipment
Journal of Central South University of Technology (English Edition) | Year: 2012

The hybrid genetic algorithm is utilized to facilitate model parameter estimation. The tri-dimensional compression tests of soil are performed to supply experimental data for identifying nonlinear constitutive model of soil. In order to save computing time during parameter inversion, a new procedure to compute the calculated strains is presented by multi-linear simplification approach instead of finite element method (FEM). The real-coded hybrid genetic algorithm is developed by combining normal genetic algorithm with gradient-based optimization algorithm. The numerical and experimental results for conditioned soil are compared. The forecast strains based on identified nonlinear constitutive model of soil agree well with observed ones. The effectiveness and accuracy of proposed parameter estimation approach are validated. © 2012 Central South University Press and Springer-Verlag Berlin Heidelberg.


Xue Q.-W.,Dalian Jiaotong University | Xue Q.-W.,State Key Laboratory of Structural Analysis for Industrial Equipment | Wei W.,Dalian Jiaotong University
Gongcheng Lixue/Engineering Mechanics | Year: 2010

Tikhonov's regularization approach has been used to solve non-linear inverse heat conduction problems, using weighted Bregman distances in the construction of regularization terms for the Tikhonov's function. Combined identifications can be achieved for non-linear inverse heat conduction with source term, thermal diffusivity and boundary conditions etc, facilitating the sensitivity analysis. Satisfactory numerical validation is performed including a preliminary investigation on the effect of noise data and the computational efficiency of different regularization terms. Results show that the proposed method can identify combined thermal parameters and boundary conditions for non-linear inverse heat conduction problems with high computational precision and anti-noisy capability. Moreover, the computational efficiency is improved with the weighted Bregman distances function as regularization terms.


Zhang H.W.,State Key Laboratory of Structural Analysis for Industrial Equipment | Fu Z.D.,State Key Laboratory of Structural Analysis for Industrial Equipment
Advances in Water Resources | Year: 2010

The coupling upscaling finite element method is developed for solving the coupling problems of deformation and consolidation of heterogeneous saturated porous media under external loading conditions. The method couples two kinds of fully developed methodologies together, i.e., the numerical techniques developed for calculating the apparent and effective physical properties of the heterogeneous media and the upscaling techniques developed for simulating the fluid flow and mass transport properties in heterogeneous porous media. Equivalent permeability tensors and equivalent elastic modulus tensors are calculated for every coarse grid block in the coarse-scale model of the heterogeneous saturated porous media. Moreover, an oversampling technique is introduced to improve the calculation accuracy of the equivalent elastic modulus tensors. A numerical integration process is performed over the fine mesh within every coarse grid element to capture the small scale information induced by non-uniform scalar field properties such as density, compressibility, etc. Numerical experiments are carried out to examine the accuracy of the developed method. It shows that the numerical results obtained by the coupling upscaling finite element method on the coarse-scale models fit fairly well with the reference solutions obtained by traditional finite element method on the fine-scale models. Moreover, this method gets more accurate coarse-scale results than the previously developed coupling multiscale finite element method for solving this kind of coupling problems though it cannot recover the fine-scale solutions. At the same time, the method developed reduces dramatically the computing effort in both CPU time and memory for solving the transient problems, and therefore more large and computational-demanding coupling problems can be solved by computers. © 2009 Elsevier Ltd. All rights reserved.


Wang Y.-F.,Dalian University of Technology | Wang Y.-F.,State Key Laboratory of Structural Analysis for Industrial Equipment | Zhao G.-X.,Dalian University of Technology | Zhao G.-X.,State Key Laboratory of Structural Analysis for Industrial Equipment
Gongcheng Lixue/Engineering Mechanics | Year: 2012

The dynamic behavior of an ice-covered cable is complicated because of the eccentricity over the cable's cross-section, which makes the in-plane and out-of-plane vibrations coupled with the torsion vibration. A three-dimensional coupling model of a suspension cable loaded by wind excitation is developed, with the wind force expressed as a nonlinear function of the angle of attack. The governing partial differential equation of motion is derived through the Hamilton's principle and discretized using the Galerkin approach. The stability region in the parametric space of the cable's equilibrium configuration is obtained using Routh-Hurwitz criterion. The critical wind speed of the Hopf bifurcation is determined and later verified numerically. The boundary shape of the stability region is obtained through an approximately analytical method in the vicinity of a given Hopf bifurcation point, by which a fair amount of computational cost is saved.


Cao X.,Dalian University of Technology | Wang Y.,Dalian University of Technology | Wang Y.,State Key Laboratory of Structural Analysis for Industrial Equipment
Structural and Multidisciplinary Optimization | Year: 2015

Topology optimization to minimize the bottom–layer temperature and the structure compliance of the multi–layered thin–walled structure is carried out in this paper. A multi–layered thin–walled structure with improved performances in load–carrying and heat insulation inspired by a species of oceanic gastropods found on a hot and highly pressurized deep–sea floor is proposed. Using genetic algorithm to perform the optimization process, it is proved that the optimal topology under integrated thermal and load conditions is a sandwich structure of three layers similar to the original bionic structure of the oceanic gastropods. Soft layer with good heat insulation is placed as the middle layer, whereas hard layers with fast heat transmission are placed as the top and bottom layers to carry load. The concept of bionic three–layered structure is then applied to the skin design of an airfoil. The analysis for aerodynamic heating of the airfoil with different skin structures shows that the bionic multi–layered structure is an optimal design in both layer thickness and layer sequence. © 2015 Springer-Verlag Berlin Heidelberg


Guo X.,State Key Laboratory of Structural Analysis for Industrial Equipment
Applied Mechanics and Materials | Year: 2012

Based on modern ideas of thermomechanics, small strain dynamic dissipation function of Hardin-Drnevich model for soils is formulated using the assumptions of the beeline and the skeleton curve shift laws. Fundamentally, for cohesionless soils, two types of cyclic strain thresholds are identified: first threshold strain and second threshold strain represent boundaries between fundamentally different dynamic characteristics of cyclic soil behavior. Comparison between the two threshold shear strain values and dynamic degradation curves obtained on exactly the same soils, the results showed that the ratio of secant modulus and maximum dynamic shear modulus for the first threshold strain are almost 1.0, and the damping ratio is almost constant. When dynamic strain level exceeds the second threshold strain, the soil behavior is considerably at nonlinear, and the primary deformation mechanism is related to fabric changes during cyclic loading. The first and the second threshold strains are therefore essential for the understanding and solving soil dynamic problems. © (2012) Trans Tech Publications.


Zhu Y.,Dalian University of Technology | Zhu Y.,State Key Laboratory of Structural Analysis for Industrial Equipment | Pan X.,Dalian University of Technology | Pan X.,State Key Laboratory of Structural Analysis for Industrial Equipment
Applied Surface Science | Year: 2014

In this paper, a 3-D Monte Carlo model for NiTi alloy thin film growth on square lattice substrate is presented. The model is based on the description of the phenomenon in terms of adsorption, diffusion and re-evaporation of different atoms on the substrate surface. In this article, multi-body NiTi potential is used to calculate diffusion activation energy. The energy which is related to the types of the atoms is equal to the total energy change of the system before and after the diffusion process happens. The simulations serve the purpose of investigation of the role of diffusion in the determination of the microstructure of the alloy clusters. The effects of the substrate temperature and the deposition rate on the morphology of the island are also presented. The island size distribution and roughness evolution have been computed and compared with our experimental results. © 2014 Elsevier B.V. All rights reserved.


Guo T.,Shenyang Blower Works | Wang Y.-F.,Shenyang Blower Works | Wang Y.-F.,Dalian University of Technology | Wang Y.-F.,State Key Laboratory of Structural Analysis for Industrial Equipment
Gongcheng Lixue/Engineering Mechanics | Year: 2011

Beetles cuticles have delicate and complicated body structures. In this paper several models are developed based on the observation of microstructures of beetle cuticles. The analysis for capability of energy-absorbing of beetle cuticles are presented with the nonlinear finite element software ANSYS/LS-DYNA. The discussions on effects of structures and materials are provided. The structures of original models are improved to make them resemble the trabecular structure of beetle cuticles for larger energy absorptions. A comparison is carried out between the improved model and cylindrical tube in terms of static and dynamic axial impact responses. The results show that the improved model absorbs more energy and performs in more stability way than the tube. This makes it an excellent structure for the device of structural crashworthy and energy absorption.


Kong X.Q.,State Key Laboratory of Structural Analysis for Industrial Equipment | Zhou P.,State Key Laboratory of Structural Analysis for Industrial Equipment | Wu C.W.,State Key Laboratory of Structural Analysis for Industrial Equipment
Computer Methods in Biomechanics and Biomedical Engineering | Year: 2011

Microneedles have recently received much attention as a novel way for transdermal drug delivery. In this paper, a numerical simulation of the insertion process of the microneedle into human skin is reported using the finite element method. A multilayer skin model consisting of the stratum corneum, dermis and underlying hypodermis has been developed. The effective stress failure criterion has been coupled with the element deletion technique to predict the complete insertion process. The numerical results show a good agreement with the reported experimental data for the deformation and failure of the skin and the insertion force. The influences of the mechanical properties of the skin and the microneedle geometry (e.g. tip area, wall angle and wall thickness) on the insertion force are discussed. The numerical results are helpful for the optimum design of the microneedles for the transdermal drug delivery system. © 2011 Taylor & Francis.

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