Study On Thermal Vibration Of Composite Thin Plate With Elastic Support

In recent years,with the aircraft speed continues to increase,the working environment of the structure is generally harsh,the surface of the thin-walled structure is often subjected to thermal load and aerodynamic load and other loads.Thermal stress can cause thermal buckling of the structure when the thermal stress caused by thermal load reaches a certain value.Aerodynamic load will induce flutter when it reachs the critical flutter pressure.These will adversely affect the fatigue strength and flight safety of the structure.In actual engineering,these structural boundary conditions are more complex,often in the form of welding or bolted connections,so it is necessary to carry out thermal vibration analysis of the wall structure of complex boundary.Using the concept of artificial spring,the complex boundary is equivalent to the elastic support boundary,by changing the spring stiffness to simulate a variety of complex boundary conditions.The mode shapes are expressed as a series of characteristic orthogonal polynomials,and then the frequency equation of thin-walled rectangular plate is deduced by Rayleigh-Ritz method.The correctness and validity of the method are verified by comparing with the results of existing literature and finite element software.In addition,the effects of the parameters such as the stiffness of the boundary spring and the aspect ratio on the natural frequency and mode are analyzed,and conducted a simple dynamic analysis and the harmonic response analysis.Based on the natural analysis of the structure,the thermal aerodynamic problem of composite laminates is investigated.The theory of von-Karman large deformation is introduced,and the dynamic model of temperature field is established by Hamilton principle.The natural frequency and mode shapes of the panel in a temperature field and the mode jump are studied,and the critical buckling temperature is solved.Then the flutter analysis of the laminates is analyzed,when considering the aerodynamic damping,the critical flutter dynamic pressure calculated by the maximum real part of the linear coefficient matrix is slightly larger than that of frequency coincidence theory.The results show that increasing the boundary spring constraint and reducing the laying angle can improve the stability of the system.And the temperature and aerodynamic pressure play an opposite role in the stability of the structure.With an aerodynamic pressure,the critical buckling temperature of the panel will vary with the velocity of the air flow.