| Engine blades are one of the most important components of aerospace structures,and their performance has a significant impact on flight safety.The blade system is a rigid-flexible coupling structure with flexible attachment and rigid body.For this type of structure,we can often simplify it to a rotating hub-flexible beam system for dynamic analysis.Aeroengine blades often work at high rotating speed,and can be affected by aerodynamic force,thermal stress,etc.,which requires them should withstand high temperature and pressure,and be with strong reliability.Therefore,it is necessary to establish a more accurate model and choose new composite materials that meet various performance requirements.In this paper,the dynamic characteristics of a hub-FGM beam system with rotating motion are studied.In order to be more compatible with the practical application,this paper not only considers the lateral bending and longitudinal stretching of the flexible beam but also adds the influence of shear angle to the model.The second kind of Lagrange’s equation is used to derive the rigid-flexible coupling dynamic equations of flexible beam system.The dynamic characteristics of several FGM beams with different parameters are studied and compared.The main work and research results are as follows:1.The research development and research status of rigid-flexible coupling kinetics and mechanical behavior of FGM structures are summarized,and the research contents and objectives of this paper are proposed.2.Taking the hub-flexible beam system as the research object,the shear effect was added based on the previous model and the deformation of the flexible beam was described by the geometrical relationship.The expressions of the potential energy and kinetic energy of the flexible beam system were deduced.By using the assumed modes method to discretize the longitudinal tensile strain,the transverse bending strain and the shear angle,the dynamic equations of rigid-flexible beam system are deduced by the second kind of Lagrange’s equation to establish a new hub-flexible beam system rigid-flexible coupling dynamic model.Simplified models of three different levels are also established by using the Taylor expansion method.3.Based on the established rigid-flexible coupled dynamic model,the rigid-flexible coupled dynamic equations of the rigid-flexible FGM system are derived.The dynamics of beam systems that perform a wide range of rotational movements are studied.By comparing with the previous model,the correctness of the model is validated,and the dynamics of the flexible beam are calculated under the condition that the large overall rotational motion is known and unknown are both investigated.4.The transverse flexural vibration of the hub-flexible beam system with rotating motion has been conducted.The transverse bending vibration equations of the system are derived.The natural frequencies of the homogeneous cross-section beam,the homogeneous wedge beam and the FGM wedge beam are calculated.The variation of natural frequency of beams under different geometrical parameters and material parameters is discussed. |
