Research On Vibration Characteristics Of Composite Cantilever Laminate

At present,all kinds of small unmanned helicopters in various fields in the world have been widely used,especially for the military field,with a very wide range of applications.For helicopters,the wing is the key to carrying the entire body of the flight,the study of the unmanned helicopter wing determines the helicopter reliability and other performance during the flight.The composite material due to its high strength and light characteristics,in the aviation field has been well applied.Due to its anisotropic characteristics,composite materials have nonlinear problems when loaded.Therefore,it is of great theoretical and practical significance to study the nonlinearity of composite materials.In this paper,we mainly study the vibration characteristics of the composite cantilever laminate.In the course of the study,we simplified the cantilever laminate of the composite material since one end of the laminate is fixed with three sides freely.The length is larger than the other two directions and the thickness of the laminate is small,so the laminate is simplified as a cantilever beam model.The main contents of this thesis are as follows.Based on Reddy's theory of high-order shear deformation plate,the displacement field of composite cantilever plate is deduced.According to the large deformation geometry equation given by Von Karman,the relationship between strain and displacement of plate and the relationship between curvature and displacement are obtained.At the same time,Nonlinear dynamic partial differential equations of composite cantilever laminate were established according to Hamilton principle.Based on Matlab,the vibration differential equations of laminated plates are solved.The plate trial functions and weight functions are selected as the combination of the free-plate vibration mode functions and the cantilever plate mode functions to improve the calculation accuracy.The natural vibration modes of the plates,Natural frequency,and on this basis,analysis of the transient load and intermittent load under the plate vibration response.The vibration characteristics of composite laminates were simulated based on Abaqus.Using the structural dynamics analysis module in Abaqus,the modal,amplitude-frequency characteristics and response analysis of the laminate were carried out.The response of the laminate under various loadings and different lay angles was calculated.The results of the analysis were in good contrast with the results of Matlab.Finally,the strength of laminates subjected to centrifugal load and surface pressure load was analyzed,and the stress of each layer of the laminates was obtained.The results show that the board in the loading conditions of stress at all positions in a safe state.