Vibration Characteristics Analysis And Vibration Isolation Research Of Straddle Type Monorail Vehicle Rolling Vibration Test Bench

As a new type of urban vehicle serving the urban rail transit system,the straddle-type monorail vehicle is widely used due to it’s unique advantages that differ from traditional dual-track vehicles: strong climbing ability,strong adaptability,low noise,small area,low construction cost,short construction period.As a new type of vehicle,a large number of operating tests are indispensable in the vehicle development and manufacturing process,but domestic monorail vehicles have fewer operating lines,and building a special test line for a single vehicle is costly and cannot be compatible with different types of vehicles.Compared with the construction of the monorail test line,the construction of the monorail vehicle rolling vibration test bench has lower cost and shorter construction period,and the advantages are more obvious.Therefore,the research and design of a straddle-type monorail vehicle rolling vibration test rig that can be compatible with different types of bogies and can simulate multiple operating conditions is of great engineering significance for improving vehicle research and reducing the construction cost.In this thesis,the structure design of the single-track rolling vibration test bench is first based on the functional and technical requirements of the test bench,including:the rotating platform of the test bench,the ultra-high adjustment platform,the rolling system and the longitudinal fixed reaction frame,and the three-dimensional modeling is carried out in the Creo software.Hypermesh and Optistruct are used to perform finite element modeling and modal analysis on the rolling system of the test rig,and the natural frequency and vibration mode of the rolling system of the test rig are obtained,paving the way for the analysis of the vibration characteristics of the rolling system.Secondly,based on the theory of frequency response analysis and random frequency response analysis,taking the traveling wheel-to-roll system and the horizontal wheel-to-roll system as the research objects,the Optistruct software is used to analyze their vibration characteristics under simple harmonic excitation and random excitation of the hydraulic actuator and the motor’s eccentric force excitation.The results show that the sixth-order mode of the traveling roller system is easy to be excited by the simple harmonic excitation of the hydraulic exciter,and the fifth-order mode of the horizontal roller system is easy to be excited.Under the random excitation of the hydraulic exciter,the probability that the maximum stress of the wheel-to-roll system is 30.95 MPa,and the power spectral density response curve has a maximum value at 86 Hz in the x,y,and z directions,which is close to The sixth-order natural frequency of the system;the probability that the maximum stress of the horizontal wheel-to-roll system is 48.36 MPa.The x-direction of the power spectral density curve has the maximum value at the fifth and seventh-order natural frequencies,and the y-direction and z-direction are at the first natural frequency.The maximum appears at the fifth and sixth-order natural frequencies.When excited by the eccentric force of the motor,the movement response to the displacement of the roller system does not have a maximum value,and the fifth-order natural frequency of the horizontal counter-rolling system is easily excited.Finally,the active vibration isolation method is adopted to design the vibration isolation system of the test bench.The vibration isolation system is designed as a first-level vibration reduction system,and the vibration isolation effect index is selected as the vibration isolation rate is less than 0.05.Through parameter design calculation,the mass of the vibration isolation base is set to 400 t,and the total stiffness of the vibration isolator is 2304 k N/m.The vibration isolation rate of the vibration isolation system is 0.049,the maximum vibration displacement is 0.46 mm,and the vibration isolation effect meets the requirements.Combining the required parameters,the vibration isolation platform structure design and the vibration isolator layout are carried out.The vibration isolation platform selects concrete materials,and the vibration isolators select 30 spring shock absorbers.In order to verify the vibration isolation effect,a dynamic model of the vibration isolation system was established in Simulink,and the impact of the stiffness of the shock absorber and the quality of the vibration isolation base on the vibration isolation effect was analyzed.The results showed that the vibration displacement of the vibration isolation system increased with the stiffness of the rubber shock absorber.However,it decreases as the mass of the vibration isolation platform increases,and the vibration displacement of the vibration isolation system is less than the limit,which again verifies that the design parameters are reasonable and the vibration isolation effect reaches the standard.