The objective of this paper is to study the nonlinear coupling internal resonance of the heave,roll,and pitch response performance of a spar platform when their frequencies are in the ratio of 2:1:1 under wave and vor...The objective of this paper is to study the nonlinear coupling internal resonance of the heave,roll,and pitch response performance of a spar platform when their frequencies are in the ratio of 2:1:1 under wave and vortex exciting loads.The three degree-of-freedom(DOF)nonlinear coupled equations are established by considering a time-varying wet surface with a first-order wave force in heave and pitch and a vortex-induced force in roll.The first-order steady-state response is solved using the multi-scale method in heave main resonance.The multiple solutions of the motion equations are discussed using the analytic method and a numerical simulation.A sensitivity analysis is conducted to test the influence of the damping and internal detuning parameter.The regions of multiple solutions are found,and the jump phenomenon exists with the changes of the wave excitation.The regions of multiple solutions depend on the values of damping and detuning parameter.展开更多
Nanotubes form clusters and are found in curved bundles in nano-tube films and nanocomposites.Separation phenomenon is sus-pected to occur in these curved bundles.In this study,the deformation of a single-wall carbon ...Nanotubes form clusters and are found in curved bundles in nano-tube films and nanocomposites.Separation phenomenon is sus-pected to occur in these curved bundles.In this study,the deformation of a single-wall carbon nanotube(SWCNT)interacting with curved bundle nanotubes is analyzed.It is assumed that the bundle is rigid and only van der Waals force acts between the nanotube and the bundle of nanotubes.A new method of model-ing geometric nonlinear behavior of the nanotube due to finite rotation and the corresponding van der Waals force is developed using co-rotational finite element method(CFEM)formulation,combined with small deformation beam theory,with the inclusion of axial force.Current developed CFEM method overcomes the limitation of linear Finite Element Method(FEM)formulation regarding large rotations and deformations of carbon nanotubes.This study provides a numerical tool to identify the critical curvature influence on the interaction of carbon nanotubes due to van der Waals forces and can provide more insight into studying irregula-rities in the electronic transport properties of adsorbed nanotubes in nanocomposites.展开更多
基金supported by the National Natural Science Foundation of China under Grant No.51279130
文摘The objective of this paper is to study the nonlinear coupling internal resonance of the heave,roll,and pitch response performance of a spar platform when their frequencies are in the ratio of 2:1:1 under wave and vortex exciting loads.The three degree-of-freedom(DOF)nonlinear coupled equations are established by considering a time-varying wet surface with a first-order wave force in heave and pitch and a vortex-induced force in roll.The first-order steady-state response is solved using the multi-scale method in heave main resonance.The multiple solutions of the motion equations are discussed using the analytic method and a numerical simulation.A sensitivity analysis is conducted to test the influence of the damping and internal detuning parameter.The regions of multiple solutions are found,and the jump phenomenon exists with the changes of the wave excitation.The regions of multiple solutions depend on the values of damping and detuning parameter.
基金This work was supported by the Texas Institute for the Intelligent Bio-Nano Materials and Structure for Aerospace Vehicles,funded by NASA[NCC-1-02038].
文摘Nanotubes form clusters and are found in curved bundles in nano-tube films and nanocomposites.Separation phenomenon is sus-pected to occur in these curved bundles.In this study,the deformation of a single-wall carbon nanotube(SWCNT)interacting with curved bundle nanotubes is analyzed.It is assumed that the bundle is rigid and only van der Waals force acts between the nanotube and the bundle of nanotubes.A new method of model-ing geometric nonlinear behavior of the nanotube due to finite rotation and the corresponding van der Waals force is developed using co-rotational finite element method(CFEM)formulation,combined with small deformation beam theory,with the inclusion of axial force.Current developed CFEM method overcomes the limitation of linear Finite Element Method(FEM)formulation regarding large rotations and deformations of carbon nanotubes.This study provides a numerical tool to identify the critical curvature influence on the interaction of carbon nanotubes due to van der Waals forces and can provide more insight into studying irregula-rities in the electronic transport properties of adsorbed nanotubes in nanocomposites.
