Designing re-entry space vehicles and high-speed aircraft requires special attention to the nonlinear thermoelastic and aerodynamic instability of their structural components.The thermal effects are important since te...Designing re-entry space vehicles and high-speed aircraft requires special attention to the nonlinear thermoelastic and aerodynamic instability of their structural components.The thermal effects are important since temperature environment brings dramatic influences on the static and dynamic behaviors of flight structures in supersonic/hypersonic regimes and is likely to cause instability,catastrophic failure and oscillations resulting in structural failure due to fatigue.In order to understand the dynamic behaviors of these"hot"structures,a double-wedge lifting surface with combining freeplay and cubic structural nonlinearities in both plunging and pitching degrees-of-freedom operating in supersonic/hypersonic flight speed regimes has been analyzed.A third order piston theory aerodynamic is used to estimate the applied nonlinear unsteady aerodynamic loads.Also considered is the loss of torsional stiffness that may be incurred by lifting surfaces subject to axial stresses induced by aerodynamic heating.The aerodynamic heating effects are estimated based on the adiabatic wall temperature due to high speed airstreams.As a recently emerging technology,the active aerothermoelastic control is aimed at providing solutions to a large number of problems involving the aeronautical/aerospace flight vehicle structures.To prevent such damaging phenomena from occurring,an application of linear and nonlinear active control methods on both flutter boundary and post-flutter behavior has been fulfilled.In this paper,modeling issues as well as numerical simulation have been presented and pertinent conclusions outlined.It is evidenced that a serious loss of torsional stiffness may induce the dynamic instability;however active control can be used to expand the flutter boundary and convert unstable limit cycle oscillations(LCO)into the stable LCO and/or to shift the transition between these two states toward higher flight Mach numbers.展开更多
The design of the re-entry space vehicles and high-speed aircraft structures requires special attention to the non-linear thermoelastic and aerodynamic instabilities.The thermal effects are important since temperature...The design of the re-entry space vehicles and high-speed aircraft structures requires special attention to the non-linear thermoelastic and aerodynamic instabilities.The thermal effects are important since temperature environment influences significantly the static and dynamic behaviors of flight structures in supersonic/hypersonic regimes.The dynamic behavior of a double-wedge lifting surface with combined freeplay and cubic stiffening structural nonlinearities in both plunging and pitching degrees-of-freedom(DOF) operating in supersonic/hypersonic flight speed regimes has been analyzed.In addition a third order piston theory aerodynamics(PTA) is used to evaluate the non-linear unsteady aerodynamic loads applied to the wing section.Loss of torsional stiffness that may be incurred by lifting surfaces subjected to axial stresses induced by aerodynamic heating is also considered.The aerodynamic heating effect is estimated based on the adiabatic wall temperature due to high speed airstreams.It is demonstrated that serious losses of torsional stiffness may occur in such lifting surfaces;the influence of various parameters such as flight condition,thickness ratio,freeplays and pitching stiffness nonlinearity are discussed.展开更多
文摘Designing re-entry space vehicles and high-speed aircraft requires special attention to the nonlinear thermoelastic and aerodynamic instability of their structural components.The thermal effects are important since temperature environment brings dramatic influences on the static and dynamic behaviors of flight structures in supersonic/hypersonic regimes and is likely to cause instability,catastrophic failure and oscillations resulting in structural failure due to fatigue.In order to understand the dynamic behaviors of these"hot"structures,a double-wedge lifting surface with combining freeplay and cubic structural nonlinearities in both plunging and pitching degrees-of-freedom operating in supersonic/hypersonic flight speed regimes has been analyzed.A third order piston theory aerodynamic is used to estimate the applied nonlinear unsteady aerodynamic loads.Also considered is the loss of torsional stiffness that may be incurred by lifting surfaces subject to axial stresses induced by aerodynamic heating.The aerodynamic heating effects are estimated based on the adiabatic wall temperature due to high speed airstreams.As a recently emerging technology,the active aerothermoelastic control is aimed at providing solutions to a large number of problems involving the aeronautical/aerospace flight vehicle structures.To prevent such damaging phenomena from occurring,an application of linear and nonlinear active control methods on both flutter boundary and post-flutter behavior has been fulfilled.In this paper,modeling issues as well as numerical simulation have been presented and pertinent conclusions outlined.It is evidenced that a serious loss of torsional stiffness may induce the dynamic instability;however active control can be used to expand the flutter boundary and convert unstable limit cycle oscillations(LCO)into the stable LCO and/or to shift the transition between these two states toward higher flight Mach numbers.
基金the China Post Doctor National Fund (No.AD4122,2008)
文摘The design of the re-entry space vehicles and high-speed aircraft structures requires special attention to the non-linear thermoelastic and aerodynamic instabilities.The thermal effects are important since temperature environment influences significantly the static and dynamic behaviors of flight structures in supersonic/hypersonic regimes.The dynamic behavior of a double-wedge lifting surface with combined freeplay and cubic stiffening structural nonlinearities in both plunging and pitching degrees-of-freedom(DOF) operating in supersonic/hypersonic flight speed regimes has been analyzed.In addition a third order piston theory aerodynamics(PTA) is used to evaluate the non-linear unsteady aerodynamic loads applied to the wing section.Loss of torsional stiffness that may be incurred by lifting surfaces subjected to axial stresses induced by aerodynamic heating is also considered.The aerodynamic heating effect is estimated based on the adiabatic wall temperature due to high speed airstreams.It is demonstrated that serious losses of torsional stiffness may occur in such lifting surfaces;the influence of various parameters such as flight condition,thickness ratio,freeplays and pitching stiffness nonlinearity are discussed.
