Research On Dynamic Characteristics Of Rotating Functionally Graded Porous Blade Reinforced By Graphene Nanoplatelets

The rotating blade is a typical high-speed rotating cantilever structure,which is widely used in various turbine machinery.As a key component of aero-engine,the dynamic characteristics of rotating blades directly affect the performance of the entire aero-engine.In recent years,with the rapid development of composite technology,a large number of new functionally graded nanocomposite with excellent comprehensive performance,such as functionally graded(FG)porous nanocomposite reinforced with graphene platelets(GPLs),have been applied to the design of aero-engine blades.Therefore,it is of great practical significance to study the dynamic characteristics of functionally graded composite blades.In this paper,the rotating functionally graded porous blade reinforced by graphene nanoplatelets is the research object.Considering the transverse vibration,the blade is simplified into a cantilever plate model,based on the energy method,the Hamilton variational principle and the Galerkin truncation method,the dynamic model of the rotating blade is established.The vibration characteristics of rotating functionally graded porous blades reinforced by graphene nanoplatelets are studied,the influence of initial geometric imperfection on the vibration characteristics of rotating functionally graded porous blades reinforced by graphene nanoplatelets is discussed,furthermore analyzes the rotating functionally graded composite blade vibration responses under centrifugal force,aerodynamic loads and rubbing force.This paper mainly studies the following aspects:(1)Based on the plate and shell vibration theory and Hamilton variational principle,the dynamic model of isotropic rotating blades was established considering the influence of centrifugal stiffening,spin softening and Coriolis forces of the rotating blades.The correctness of the model was verified by comparing with relevant references and finite element results.The effects of dimensionless speed,fineness ratio and length-width ratio on the dynamic characteristics of isotropic rotating blades were analyzed.(2)Based on the dynamic model of the isotropic rotating blade and the laminated plate model,the dynamic model of spinning functionally graded porous blades reinforced by graphene nanoplatelets was established.After the convergence analysis and verification of the dynamic model,the effects of the weight fraction,geometric parameters and distribution patterns of graphene-enhanced materials,as well as the pore distribution pattern and porosity coefficient of the metal foam matrix material on the dynamic characteristics of the functionally graded composite blades were discussed.(3)On the basis of the dynamic model of rotating functionally porous nanocomposite blade reinforced by graphene nanoplatelets,the initial geometric imperfection function is introduced,and the dynamic model of the rotating functionally graded nanocomposite blade with initial geometric imperfection was established and verified.The influence of global and local initial geometric imperfection related parameters on the dynamic characteristics of functionally graded composite blades are discussed.(4)Based on the dynamic model of rotating functionally porous nanocomposite blade reinforced by graphene nanoplatelets,the system dynamic model of functionally graded nanocomposite blade considering centrifugal force,aerodynamic force and rubbing force was established.The vibration response of blade under centrifugal force,aerodynamic force and rub-impact force is solved by Newmark method.The effects of the amplitude and frequency of the aerodynamic excitation force,the rotation speed,the amount of intrusion and the friction coefficient when the blade is rubbed on the vibration response of the blade were discussed.