Owing to their high flexibility and directional actuation capabilities,macro fiber composites(MFCs)have attracted significant attention for the active control of structures,especially in the nonlinear vibration suppre...Owing to their high flexibility and directional actuation capabilities,macro fiber composites(MFCs)have attracted significant attention for the active control of structures,especially in the nonlinear vibration suppression applications for large-scale flexible structures.In this paper,an MFC-based self-feedback system is introduced for the active control of geometrically nonlinear steady-state forced vibrations in functionally graded carbon nanotube reinforced composite(FG-CNTRC)plates subject to transverse mechanical loads.Based on the first-order shear deformation theory and the von Kármán nonlinear strain-displacement relationship,the nonlinear vibration control equations of the plate with MFC sensor and actuator layers are derived by Hamilton's principle.These equations are discretized by the finite element method(FEM),and solved by the Newton-Raphson and direct iterative methods.A velocity feedback control algorithm is introduced,and the effects of the control gain and the MFC actuator position on the nonlinear vibration active control effectiveness are analyzed.Additionally,a nonlinear resonance analysis is carried out,considering the effects of carbon nanotube(CNT)volume fraction and distribution type.The results indicate that the intrinsic characteristics of the structures significantly influence the vibration behavior.Furthermore,the appropriate selections of control gain and MFC position are crucial for the effective active control of the structures.The present work provides a promising route of the active and efficient nonlinear vibration suppression for various thin-walled structures.展开更多
The microstructure polymer optical fibre (mPOF) inscribed long period grating (LPG) offers a wide field of application in strain sensors arena within the materials elastic limit. Flexible innovative macro fibre compos...The microstructure polymer optical fibre (mPOF) inscribed long period grating (LPG) offers a wide field of application in strain sensors arena within the materials elastic limit. Flexible innovative macro fibre composite (MFC) actuator generates electromechanical force under DC driving voltage. We propose a novel method for Bragg wavelength blue shifting through stretch tuning of mPOF LPG in axial direction under applied DC voltage on attached MFC with LPG. The grating period of mPOF LPG changes refractive index and causes blue shift of Bragg grating fibre wavelength. The shifting governs on the values of generated electromechanically strain transfer from flexible MFC to mPOF LPG and they have potential applications in strain sensor.展开更多
Piezoelectric materials are capable of actuation and sensing and have been used in a wide variety of smart devices and structures.Active fiber composite and macro fiber composite are newly developed types of piezoelec...Piezoelectric materials are capable of actuation and sensing and have been used in a wide variety of smart devices and structures.Active fiber composite and macro fiber composite are newly developed types of piezoelectric composites,and show superior properties to monolithic piezoelectric wafer due to their distinctive structures.Numerous work has focused on the performance prediction of the composites by evaluation of structural parameters and properties of the constituent materials with analytical and numerical methods.Various applications have been explored for the piezoelectric fiber composites,including vibration and noise control,health monitoring,morphing of structures and energy harvesting,in which the composites play key role and demonstrate the necessity for further development.展开更多
Investigated by this study is an MFC actuator attached to the surface of a Carbon Fiber Reinforced Polymer(CFRP)composite beam to form a beam actuator system.Analytically capturing the characteristics of such system i...Investigated by this study is an MFC actuator attached to the surface of a Carbon Fiber Reinforced Polymer(CFRP)composite beam to form a beam actuator system.Analytically capturing the characteristics of such system is essential.A novel analytical methodology considering the transverse shear strain and active stiffening effect is proposed,which was newly applied to analyze the static and dynamic behaviors of the beam actuator system.The governing equations of the beam actuator system were obtained via generalized Hamilton’s principle.A distributed transfer function formulation was developed.Then,the closed form solution was derived by using the Green’s function.Frequency response,natural frequencies,and modal shapes of the beam actuator system were obtained.The solution is analytical without using any truncated series or admissible functions at any arbitrary boundary conditions.Finite Element Method(FEM)results were also obtained to compare with that of the proposed method.The predictions of the analyses were verified experimentally,which shows the correctness and effectiveness of the proposed method.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.12072003 and 12372003)Beijing Natural Science Foundation of China(No.1222001)。
文摘Owing to their high flexibility and directional actuation capabilities,macro fiber composites(MFCs)have attracted significant attention for the active control of structures,especially in the nonlinear vibration suppression applications for large-scale flexible structures.In this paper,an MFC-based self-feedback system is introduced for the active control of geometrically nonlinear steady-state forced vibrations in functionally graded carbon nanotube reinforced composite(FG-CNTRC)plates subject to transverse mechanical loads.Based on the first-order shear deformation theory and the von Kármán nonlinear strain-displacement relationship,the nonlinear vibration control equations of the plate with MFC sensor and actuator layers are derived by Hamilton's principle.These equations are discretized by the finite element method(FEM),and solved by the Newton-Raphson and direct iterative methods.A velocity feedback control algorithm is introduced,and the effects of the control gain and the MFC actuator position on the nonlinear vibration active control effectiveness are analyzed.Additionally,a nonlinear resonance analysis is carried out,considering the effects of carbon nanotube(CNT)volume fraction and distribution type.The results indicate that the intrinsic characteristics of the structures significantly influence the vibration behavior.Furthermore,the appropriate selections of control gain and MFC position are crucial for the effective active control of the structures.The present work provides a promising route of the active and efficient nonlinear vibration suppression for various thin-walled structures.
文摘The microstructure polymer optical fibre (mPOF) inscribed long period grating (LPG) offers a wide field of application in strain sensors arena within the materials elastic limit. Flexible innovative macro fibre composite (MFC) actuator generates electromechanical force under DC driving voltage. We propose a novel method for Bragg wavelength blue shifting through stretch tuning of mPOF LPG in axial direction under applied DC voltage on attached MFC with LPG. The grating period of mPOF LPG changes refractive index and causes blue shift of Bragg grating fibre wavelength. The shifting governs on the values of generated electromechanically strain transfer from flexible MFC to mPOF LPG and they have potential applications in strain sensor.
基金Project(51072235) supported by the National Natural Science Foundation of ChinaProject(11JJ1008) supported by the Natural Science Foundation of Hunan Province,China+2 种基金Project(20110162110044) supported by the PhD Program Foundation of Ministry of Education of ChinaProject(7433001207) supported by Hunan Provincial Innovation Foundation for Postgraduate,ChinaProject(2001JF3215) supported by Hunan Provincial Science and Technology Plan,China
文摘Piezoelectric materials are capable of actuation and sensing and have been used in a wide variety of smart devices and structures.Active fiber composite and macro fiber composite are newly developed types of piezoelectric composites,and show superior properties to monolithic piezoelectric wafer due to their distinctive structures.Numerous work has focused on the performance prediction of the composites by evaluation of structural parameters and properties of the constituent materials with analytical and numerical methods.Various applications have been explored for the piezoelectric fiber composites,including vibration and noise control,health monitoring,morphing of structures and energy harvesting,in which the composites play key role and demonstrate the necessity for further development.
文摘Investigated by this study is an MFC actuator attached to the surface of a Carbon Fiber Reinforced Polymer(CFRP)composite beam to form a beam actuator system.Analytically capturing the characteristics of such system is essential.A novel analytical methodology considering the transverse shear strain and active stiffening effect is proposed,which was newly applied to analyze the static and dynamic behaviors of the beam actuator system.The governing equations of the beam actuator system were obtained via generalized Hamilton’s principle.A distributed transfer function formulation was developed.Then,the closed form solution was derived by using the Green’s function.Frequency response,natural frequencies,and modal shapes of the beam actuator system were obtained.The solution is analytical without using any truncated series or admissible functions at any arbitrary boundary conditions.Finite Element Method(FEM)results were also obtained to compare with that of the proposed method.The predictions of the analyses were verified experimentally,which shows the correctness and effectiveness of the proposed method.
