Dynamic Characteristics And Vibration Fatigue Analysis Of Typical Composite Structures At High Temperature

With the tremendous technological breakthroughs made by human beings in the field of aviation and aerospace in the past 100 years and the strong impetus of military demand brought by the game between big powers,countries have invested a lot of resources to develop the defensive and combat capabilities in the near space.With the pursuit of higher Mach number,larger flight airspace and stronger service performance of high-speed aircraft in various countries,a large number of new materials and structures have been applied to systematically evaluate the strength performance of high-speed aircraft structural system under harsh aerodynamic,thermal and dynamic loads(vibration and noise)environment.Composite materials have the characteristics of low density,high specific stiffness and high specific modulus,which can meet the technical requirements of hypersonic vehicle.Therefore,they have attracted much attention.The mechanical properties of carbon fiber materials and ceramic matrix materials under high temperature environment have high research value.Firstly,the existing high temperature test technology and measurement technology are summarized.The latest development of high temperature test technology and measurement technology at home and abroad is described.The development status of resin-based and ceramic-based composites is summarized.Secondly,the typical structure of Bismaleimide resin-based carbon fiber composites was tested by thermal modal test.The thermal modal test was carried out for the laminates with different layers.The change trend of elastic modulus,natural frequency and damping ratio at different temperatures was measured.The dynamic parameters of the composites were checked by dynamic method,and the heating uniformity of quartz lamp array was discussed.The effects of different heat preservation methods on heating uniformity were compared.The modal tests of conical,semi-conical and semi-cylindrical composite structures were carried out at room and high temperatures,and the characteristics of natural frequencies and damping ratios of curved surface structures varying with temperature were summarized.Finally,heat transfer and thermal vibration analysis of ZrB2-based super-high temperature ceramic cover-plate TPS are carried out.Fine heat transfer calculation of the test piece is carried out for the "heater + test piece" composite structure model.The model of the cover-plate TPS structure is established.The dynamic model is revised based on the measured data of shaking table excitation and vibration response.The results of temperature,dynamic stress and fatigue life of the key parts are given.