Based on the generalized vaxiational principle of magneto-thermo-elasticity of a ferromagnetic thin shell established （see, Analyses on nonlinear coupling of magneto-thermo- elasticity of ferromagnetic thin shell--I...Based on the generalized vaxiational principle of magneto-thermo-elasticity of a ferromagnetic thin shell established （see, Analyses on nonlinear coupling of magneto-thermo- elasticity of ferromagnetic thin shell--I）, the present paper developed a finite element modeling for the mechanical-magneto-thermal multi-field coupling of a ferromagnetic thin shell. The numerical modeling composes of finite element equations for three sub-systems of magnetic, thermal and deformation fields, as well as iterative methods for nonlinearities of the geometrical large-deflection and the multi-field coupling of the ferromagnetic shell. As examples, the numerical simulations on magneto-elastic behaviors of a ferromagnetic cylindrical shell in an applied magnetic field, and magneto-thermo-elastic behaviors of the shell in applied magnetic and thermal fields are carried out. The results are in good agreement with the experimental ones.展开更多
The human skull, composed of tabula extema, tabula intema, and a porous diploe sandwiched in between, is deformed with changing intracranial pressure （ICP）. Because the human skull＇s thickness is only 6 mm, it is s...The human skull, composed of tabula extema, tabula intema, and a porous diploe sandwiched in between, is deformed with changing intracranial pressure （ICP）. Because the human skull＇s thickness is only 6 mm, it is simplified as a thin-walled shell. The objective of this article is to analyze the strain of the thin-wailed shell by the stress-strain calculation of a human skull with changing ICP. Under the same loading conditions, using finite element analysis （FEA）, the strains of the human skull were calculated and the results were compared with the measurements of the simulative experiment in vitro. It is demonstrated that the strain of the thin-walled shell is totally measured by pasting the one-way strain foils on the exterior surface of the shell with suitable amendment for data. The amendment scope of the measured strain values of the thin-walled shell is from 13.04% to 22.22%.展开更多
Current patch test for Mindlin plate element only satisfies the zero shear deformation condition.The patch test of non-zero constant shear for Mindlin plate problem cannot be performed.For shell element, the patch tes...Current patch test for Mindlin plate element only satisfies the zero shear deformation condition.The patch test of non-zero constant shear for Mindlin plate problem cannot be performed.For shell element, the patch test does not even exist.Based on the theory of enhanced patch test proposed by Chen W J (2006),the authors proposed the enhanced patch test function for Mindlin plate and thin cylindrical shell elements.This enhanced patch test function can be used to assess the convergence of the Mindlin plate and cylindrical thin shell elements.展开更多
Based on the consistent symmetrizable equilibrated(CSE) corotational formulation,a linear triangular flat thin shell element with 3 nodes and 18° of freedom,constructed by combination of the optimal membrane elem...Based on the consistent symmetrizable equilibrated(CSE) corotational formulation,a linear triangular flat thin shell element with 3 nodes and 18° of freedom,constructed by combination of the optimal membrane element and discrete Kirchhoff triangle(DKT) bending plate element,was extended to the geometric nonlinear analysis of thin shells with large rotation and small strain.Through derivation of the consistent tangent stiffness matrix and internal force vector,the corotational nonlinear finite element equations were established.The nonlinear equations were solved by using the Newton-Raphson iteration algorithm combined with an automatic load controlled technology.Three typical case studies,i.e.,the slit annular thin plate,top opened hemispherical shell and cylindrical shell,validated the accuracy of the formulation established in this paper.展开更多
On the basis of the finite element corotational formulation for geometric nonlinear static analysis of thin shells with large rotation and small strain established before and from the generalized-α time integration a...On the basis of the finite element corotational formulation for geometric nonlinear static analysis of thin shells with large rotation and small strain established before and from the generalized-α time integration algorithm, the energy conserving and decaying algorithms for corotational formulation nonlinear dynamic response analysis of thin shells are established in this paper. Responses are solved by means of a predictor-corrector procedure. In the case of ignoring the structural damping, the conserving or decaying total energy of structure and the controllable numerical damping for high frequency responses can ensure the numerical stability of the algorithm. The inertial parts are linearly interpolated directly in the fixed global coordinate system by using the element nodal displacement in the global coordinate system for obtaining the constant mass matrix, while the elastic parts adopt the corotational formulation. Hence, the whole formulation obtained in this paper is element independent. Through three typical numerical examples, the performances of the algorithm in this paper were compared with those of the classical Newmak and HHT-α algorithms to indicate that the algorithm in this paper could accurately solve nonlinear dynamic responses of thin shells with large displacements and large rotations.展开更多
基金supported by he National Natural Science Foundation of China (No.10872081)the Fok Ying-Tong Education Foundation for Young Teachers in the Higher Education Institutions of China (No.111005)
文摘Based on the generalized vaxiational principle of magneto-thermo-elasticity of a ferromagnetic thin shell established （see, Analyses on nonlinear coupling of magneto-thermo- elasticity of ferromagnetic thin shell--I）, the present paper developed a finite element modeling for the mechanical-magneto-thermal multi-field coupling of a ferromagnetic thin shell. The numerical modeling composes of finite element equations for three sub-systems of magnetic, thermal and deformation fields, as well as iterative methods for nonlinearities of the geometrical large-deflection and the multi-field coupling of the ferromagnetic shell. As examples, the numerical simulations on magneto-elastic behaviors of a ferromagnetic cylindrical shell in an applied magnetic field, and magneto-thermo-elastic behaviors of the shell in applied magnetic and thermal fields are carried out. The results are in good agreement with the experimental ones.
文摘The human skull, composed of tabula extema, tabula intema, and a porous diploe sandwiched in between, is deformed with changing intracranial pressure （ICP）. Because the human skull＇s thickness is only 6 mm, it is simplified as a thin-walled shell. The objective of this article is to analyze the strain of the thin-wailed shell by the stress-strain calculation of a human skull with changing ICP. Under the same loading conditions, using finite element analysis （FEA）, the strains of the human skull were calculated and the results were compared with the measurements of the simulative experiment in vitro. It is demonstrated that the strain of the thin-walled shell is totally measured by pasting the one-way strain foils on the exterior surface of the shell with suitable amendment for data. The amendment scope of the measured strain values of the thin-walled shell is from 13.04% to 22.22%.
基金Supported by the National Natural Science Foundation of China(Grant Nos.50479058 and 10672032)
文摘Current patch test for Mindlin plate element only satisfies the zero shear deformation condition.The patch test of non-zero constant shear for Mindlin plate problem cannot be performed.For shell element, the patch test does not even exist.Based on the theory of enhanced patch test proposed by Chen W J (2006),the authors proposed the enhanced patch test function for Mindlin plate and thin cylindrical shell elements.This enhanced patch test function can be used to assess the convergence of the Mindlin plate and cylindrical thin shell elements.
基金supported by the National Natural Science Foundation of China (Grant No. 51075208)the Innovation Project for Graduate Students of Jiangsu Province (Grant No. CX07B-162z)the Fund for Innovative and Excellent Doctoral Dissertation of NUAA (Grant No.BCXJ07-01)
文摘Based on the consistent symmetrizable equilibrated(CSE) corotational formulation,a linear triangular flat thin shell element with 3 nodes and 18° of freedom,constructed by combination of the optimal membrane element and discrete Kirchhoff triangle(DKT) bending plate element,was extended to the geometric nonlinear analysis of thin shells with large rotation and small strain.Through derivation of the consistent tangent stiffness matrix and internal force vector,the corotational nonlinear finite element equations were established.The nonlinear equations were solved by using the Newton-Raphson iteration algorithm combined with an automatic load controlled technology.Three typical case studies,i.e.,the slit annular thin plate,top opened hemispherical shell and cylindrical shell,validated the accuracy of the formulation established in this paper.
基金supported by the National Natural Science Foundation of China (Grant No. 51075208)the Innovation Project for Graduate Students of Jiangsu Province (Grant No. CX07B-162z)the Fund for Innovative and Excellent Doctoral Dissertation of NUAA (Grant No. BCXJ07-01)
文摘On the basis of the finite element corotational formulation for geometric nonlinear static analysis of thin shells with large rotation and small strain established before and from the generalized-α time integration algorithm, the energy conserving and decaying algorithms for corotational formulation nonlinear dynamic response analysis of thin shells are established in this paper. Responses are solved by means of a predictor-corrector procedure. In the case of ignoring the structural damping, the conserving or decaying total energy of structure and the controllable numerical damping for high frequency responses can ensure the numerical stability of the algorithm. The inertial parts are linearly interpolated directly in the fixed global coordinate system by using the element nodal displacement in the global coordinate system for obtaining the constant mass matrix, while the elastic parts adopt the corotational formulation. Hence, the whole formulation obtained in this paper is element independent. Through three typical numerical examples, the performances of the algorithm in this paper were compared with those of the classical Newmak and HHT-α algorithms to indicate that the algorithm in this paper could accurately solve nonlinear dynamic responses of thin shells with large displacements and large rotations.
