Research On Dynamic Properties Of Rubber Isolator Based On A Certain Turboprop Engine

The rubber isolator is one of the most important airborne equipment parts for aeroengine.It was installed in aero-engine to isolate the vibration transmission between engine and the aircraft.Due to nonlinear dynamic characteristics of rubber materials,the nonlinear dynamic characteristics of the rubber isolator were studied to meet the isolation performance of the rubber isolatior for a certain turboprop engine in this paper.Research results have important theoretical value and engineering application.The main contents and innovations were researched as following:(1)A six-parameter fractional derivative model(SPFDM)was developed and three dimensional constitutive relationship was deduced based on the five-parameter fractional derivative model of frequency-dependent.The relaxation time d was considered and the physical meaning of b and c was further illustrated for the SPFDM.Experimental result of butyl rubber's constitutive relations showed that the viscoelastic characteristics can be described with the SPFDM for rubber materials better.The proposed SPFDM possessed academic innovation value.(2)A nonlinear dynamic model of rubber isolator was established about the frequency and amplitude parallel connection.The results by experimental verification showed that SPFDM and friction force model could describe dynamic characteristics model of rubber isolators better.And the influence of model parameters for dynamic stiffness was also studied.At last,Quantitiative results of displacement response were given by central difference method.(3)Nonlinear dynamics finite element equations were established about the rubber isolator according to the rubber constitutive relationship.The dynamic response of rubber isolator was solved under different frequencies.And the results of dynamic response experiment showed that nonlinear equation was correct.The nonlinear dynamic finite element equation proposed in this paper provides a theoretical reference for finding accurate solution of dynamic characteristics about viscoelastic material.(4)Acorrding to the equivalent mass of a certain turboprop engine,nonliear dynamics finite element equations of the rubber isolator-mass system were established.Experimental results showed the nonlinear finite element equation can accurately predict transmissibility characteristics about rubber isolator-mass systems.This method,which had the engineering application value,provided theoretical basis for load condition and structure design of rubber isolator about the turboprop engine.(5)A mathematical equation was suggested according to the time-temperature superposition principle about the mirror relationship between the temperature and frequency.The seven-parameter fractional derivative temperature spectrum model(SPFDTM)was established.The dynamic characteristics and parameter identification method were studied.The model proposed in this paper provides a theoretical reference for considering the temperature accumulation effect of rubber isolator.In consulsion,first,nonlinear constitutive model of rubber material was presented.Second,nonlinear dynamic model of rubber isolator was established.Third,nonlinear finite element equations were studied.At last,dynamic model of temperature-dependent was derived.These methods and results which had the engineering application value provided theoretical basis for designing rubber isolators.