| Due to the changes of flight mission and requirements,as well as the progress of basic science such as materials and mechanics,lightweight structures with large slenderness ratio or aspect ratio are widely used in flight vehicle design.Thus,the elastic characteristics of this kind of flight vehicle are more obvious,and the aeroelastic problem is more prominent.Therefore,the development of aeroelastic analysis is of great significance.At the same time,with the extensive application of a large number of advanced new materials in the aerospace field,the randomness of structural parameters of flight vehicle is enhanced.At present,the research on aeroelastic problems is mainly carried out under the assumption that the structural parameters are deterministic.The role played by the randomness of structural parameters in this problem has not received much attention.However,it is of great significance to study the role of random structural parameters in aeroelastic problems for exploring the whole picture of such problems.Therefore,based on the existing aeroelastic research methods and introducing the relevant basic theories of stochastic structure analysis,a research method which can effectively and accurately analyze the influence of structural random factors on aeroelastic response and stability is established in this thesis.The ultimate purpose of this thesis is to provide feasible ideas for aeroelastic analysis of stochastic structures.In this thesis,the typical aeroelastic response and stability problems of slender body and high aspect ratio flight vehicle under the influence of structural random factors are studied.The main contents are as follows:(1)Based on Hamilton principle,the slender body vehicle is simplified as a free-free Euler Bernoulli beam,and the aeroelastic dynamic model under thrust and aerodynamic force is established.The stochastic finite element method(SFEM)based on local average is used to discretize the dynamic model to obtain the statistical characteristics of the stochastic aeroelastic response.The simulation results are verified by Monte Carlo simulation.On this basis,the influence of structural random factors on aeroelastic response is further analyzed.(2)Based on the SFEM,the statistical characteristics expression of vibration modes of slender bodies are derived.Furthermore,the first and second order recursive equations are derived to study the influence of structural random factors on structural stability under thrust and aerodynamic force.The expression of statistical characteristics of random generalized eigenvalues is obtained,and the corresponding simulation verification is carried out.(3)Based on the large deformation theory,finite element method and finite state unsteady aerodynamic force,the aeroelastic dynamic model of high aspect ratio wing is established.Based on the local average method and perturbation method,the first and second order recursive stochastic nonlinear finite element equations of wing considering the influence of structural random factors are derived.The statistical characteristic expression of aeroelastic response of wing is obtained,and the result of this method is verified by Monte Carlo simulation.(4)Based on the classical two-dimensional flutter model and the flutter model of high aspect ratio wing,the first-order and second-order recursive equations are derived by using perturbation theory.Based on the convex model theory,the upper and lower bounds of the characteristics of the closed-loop flutter system under the action of structural random factors are derived.The results are verified by simulation,and its effect on flutter critical velocity is further analyzed. |
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