Research On Vibration Band Gaps Properties Of Periodic Track Structures And Dynamic Vibration Absorber

The vibration band gaps properties of periodic structures provided some new perspectives and ideas for vibration and noise reduction of engineering structures,and has been widely studied in vibration and noise control.However,the study on vibration band gaps properties of railway track,a typical periodic structure,is not enough,and the vibration control based on band gaps principle is rarely reported.This dissertation make in-depth research on band gaps properties of periodic track structures,and based on band gaps principle,vibration control of track structure by rail dynamic vibration absorber was studied from wave propagation features.1)In the terms of the band gaps properties,based on the existing theoretical study,a periodic track structures modal was established with finite element method,the band gaps properties of periodic track structures were studied,as well as the effects of the fastener stiffness,fastener width and rail temperature force.2)In the terms of the vibration control,a local resonance band gap appeared because of the vibration absorber and vibration response in the band gap will be greatly attenuated.Then the tuning band gap behavior of vibration absorber by changing designing parameters is analyzed,it is shown that:Local resonance band gap move with the change of natural frequency of absorber.Two types of band gaps(locally resonant and Bragg band gaps)can exactly couple together to form a combined super-wide band gap and they can switch positions.The width of Bragg band gap will increase as the local resonance approached.The natural frequency of absorber can appear in a Bragg band gap,and even more surprisingly,in a pass band.In the case of not changing the structural form and natural frequency of absorber,only to increase the quality and stiffness of absorber can broaden band gap.Finally,the optimization design of absorber is researched.The results showed the principle of the band gap broadening theory with M-SDOF-DVA and the effect of mass redistribution.We should distribute more quality to the absorber which impact on the band gap at "pinned-pinned" resonance frequency.The changing of rail temperature force has little effect on the local resonance band gap,in order to obtain stable frequency band,the materials that changed fewer with temperature should be selected as far as possible.