| There is a common saying,"Striving to reduce the weight of each gram of the aircraft.",in all the aerospace divisions around the world.The lightweight design of the structure is the eternal theme of aerospace.With the continuous development of production and applied technologies for manufactuing composite mateials,polymerbased composite materials represented by fibers / epoxy with high specific strength and rigidity have gradually become the first choice of materials in aircraft structural design.As engine acts as the key component in an aircraft,the improvement of its thrust-toweight ratio has always been a hotspot of research all over the world.While The improvement from traditional methods is limited,the use of advanced composite materials for lightweighting will be effective.The adapter structure of the rocket engine accounts for a large proportion of the entire engine structure weight.If composite materials are used in adapter for weight reduction,the engine thrust-to-weight ratio and overall performance will be obviously improved.Therefore,based on the mechanics and applied technology of composite materials,this thesis will present the lightweight design of the adapter structure of the rocket engine and study its characteristic mechanical properties.This thesis firstly describes the improvement being made on the design of the frame structure for a rocket engine according to the features of Chinese rockets,and conducts a theoretical study on the axial pressure performance of the frame structure.Through preliminary analysis of the frame structure under the axial load,The simplified theoretical model of the adapter structure is established.Based on structural mechanics and mechanics of materials,the theoretical derivation and failure mode analysis of the axial load of the frame structure are conducted.By building the composite damage evolution model via the finite element method,the composite adapter main load-bearing tubes and the overall frame structure are studied via the numerical modelling.During the flight of the rocket,the thrust of the engine will be axially deflected due to the change of attitude and air resistance of the rocket,and the adapter of the rocket engine is subjected to the lateral force and torque.The finite element method is applied to analyse the stiffness of the lateral force and torque of the composite material adapter,and study the influence of the different structural parameters of the composite material adapter on the load bearing performance of the lateral force and torque in different directions.Finally,with the composite material adapter structure being used as the main loadbearing component of the rocket,the vibration from the engine’s servo mechanism,turbo pump,and liquid pipeline will make a impact on it during the rocket flight.Therefore,The dynamic mechanical properties of the composite material adapter structure are studied by the finite element method.The influence of the structural parameters of the composite material adapter on its eigenvalue,fundamental frequency and model vibration mode is mainly analyzed.At the same time,by analysing the steady-state dynamics of the composite material adapter structure,The frequency response of the structure with different wall thicknesses under harmonic excitation is studied. |
