Based on the theory of Timoshenko and thin-walled beams, a new finite element model of spatial thin-walled beams with general open cross sections is presented in the paper, in which several factors are included such a...Based on the theory of Timoshenko and thin-walled beams, a new finite element model of spatial thin-walled beams with general open cross sections is presented in the paper, in which several factors are included such as lateral shear deformation, warp generated by nonuni- form torsion and second-order shear stress, coupling of flexure and torsion, and large displacement with small strain. With an additional internal node in the element, the element stiffness matrix is deduced by incremental virtual work in updated Lagrangian （UL） formulation. Numerical examples demonstrate that the presented model well describes the geometrically nonlinear property of spatial thin-walled beams.展开更多
Based on the theories of Bernoulli-Euler beams and Vlasov's thin-walled members,a new geometrical and physical nonlinear beam element model is developed by applying an interior node in the element and independent ...Based on the theories of Bernoulli-Euler beams and Vlasov's thin-walled members,a new geometrical and physical nonlinear beam element model is developed by applying an interior node in the element and independent interpolations on bending angles and warp,in which factors such as traverse shear deformation,torsional shear deformation and their coupling,coupling of flexure and torsion,and second shear stress are all considered.Thereafter,geometrical nonlinear strain in total Lagarange(TL) and the corresponding stiffness matrix are formulated.Ideal plastic model is applied to physical nonlinearity to comply with the yield rule of Von Mises and incremental relationship of Prandtle-Reuss.Elastoplastic stiffness matrix is derived by numerical integration on the basis of the finite segment method.Examples show that the developed model is feasible in analysis of thin-walled structures with high accuracy.展开更多
The flexible attachments of spacecraft may undergo Thermally Induced Vibration(TIV)on orbit due to the suddenly changed solar heating. The unstable TIV, called thermal-flutter, can cause serious damage to the spacecra...The flexible attachments of spacecraft may undergo Thermally Induced Vibration(TIV)on orbit due to the suddenly changed solar heating. The unstable TIV, called thermal-flutter, can cause serious damage to the spacecraft. In this paper, the coupled bending-torsion thermal vibration equations for an open thin-walled circular cantilever beam are established. By analyzing the stability of these equations based on the first Lyapunov method, the thermal-flutter criterion can be obtained. The criterion is very different form that of closed thin-walled beams because the torsion has great impact on the stability of the TIV for open thin-walled beams. Several numerical simulations are conducted to demonstrate that the theoretical predictions agree very well with the finite element results, which mean that the criterion are reliable.展开更多
Origami foldcore structures can be used in thin-walled sandwich panels to provide unique advantages over traditional honey-comb structures.For instance,their continuously connected space is available for flowing throu...Origami foldcore structures can be used in thin-walled sandwich panels to provide unique advantages over traditional honey-comb structures.For instance,their continuously connected space is available for flowing through cooling liquid or compact pipeline placement.However,origami foldcores suffer from relatively low-energy absorption.This paper proposes a new design of energy-absorbing foldcore structures for sandwich panels,including the geometric design,experimental tests,numerical parametric study,and theoretical estimation of energy absorption.Origami initiators are introduced to the Miura foldcores to induce a failure mode with more transverse folds,which is not common for regular foldcore structures.As a result,60%higher energy absorption and tunable load uniformity can be achieved.展开更多
基金supported by the National Science Fund for Distinguished Young Scholars (No. 50725826).
文摘Based on the theory of Timoshenko and thin-walled beams, a new finite element model of spatial thin-walled beams with general open cross sections is presented in the paper, in which several factors are included such as lateral shear deformation, warp generated by nonuni- form torsion and second-order shear stress, coupling of flexure and torsion, and large displacement with small strain. With an additional internal node in the element, the element stiffness matrix is deduced by incremental virtual work in updated Lagrangian （UL） formulation. Numerical examples demonstrate that the presented model well describes the geometrically nonlinear property of spatial thin-walled beams.
基金supported by the National Natural Science Foundation of China(Grant No.50725826)
文摘Based on the theories of Bernoulli-Euler beams and Vlasov's thin-walled members,a new geometrical and physical nonlinear beam element model is developed by applying an interior node in the element and independent interpolations on bending angles and warp,in which factors such as traverse shear deformation,torsional shear deformation and their coupling,coupling of flexure and torsion,and second shear stress are all considered.Thereafter,geometrical nonlinear strain in total Lagarange(TL) and the corresponding stiffness matrix are formulated.Ideal plastic model is applied to physical nonlinearity to comply with the yield rule of Von Mises and incremental relationship of Prandtle-Reuss.Elastoplastic stiffness matrix is derived by numerical integration on the basis of the finite segment method.Examples show that the developed model is feasible in analysis of thin-walled structures with high accuracy.
文摘The flexible attachments of spacecraft may undergo Thermally Induced Vibration(TIV)on orbit due to the suddenly changed solar heating. The unstable TIV, called thermal-flutter, can cause serious damage to the spacecraft. In this paper, the coupled bending-torsion thermal vibration equations for an open thin-walled circular cantilever beam are established. By analyzing the stability of these equations based on the first Lyapunov method, the thermal-flutter criterion can be obtained. The criterion is very different form that of closed thin-walled beams because the torsion has great impact on the stability of the TIV for open thin-walled beams. Several numerical simulations are conducted to demonstrate that the theoretical predictions agree very well with the finite element results, which mean that the criterion are reliable.
基金funded by the National Natural Science Foundation of China(Grant No.12202320)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2021A1515110589).
文摘Origami foldcore structures can be used in thin-walled sandwich panels to provide unique advantages over traditional honey-comb structures.For instance,their continuously connected space is available for flowing through cooling liquid or compact pipeline placement.However,origami foldcores suffer from relatively low-energy absorption.This paper proposes a new design of energy-absorbing foldcore structures for sandwich panels,including the geometric design,experimental tests,numerical parametric study,and theoretical estimation of energy absorption.Origami initiators are introduced to the Miura foldcores to induce a failure mode with more transverse folds,which is not common for regular foldcore structures.As a result,60%higher energy absorption and tunable load uniformity can be achieved.
