Low Frequency And Wide Band Gap Vibration Reduction Based On Chiral Structure Of Four Ligaments

The study of vibration control is very important for the safety and stability of hydraulic structures.The vibration of hydraulic structure is induced by the high speed water flow when the dam is discharging flood,and the severe vibration of the generating set is generated when the hydropower station is running.Long-term vibration can damage generator sets and hydraulic structures.The chiral structure of the four ligaments is used to control the elastic wave in the low frequency range.Compared with the traditional vibration damping method,the chiral structure of the fo ur ligaments can use the structure itself to achieve vibration attenuation.In this paper,the structural characteristics of the chiral performance band of the four ligaments and the propagation characteristics of elastic waves are studied by structural design and material parameter measurement.Finally,the vibration reduction tests of chiral structures of four ligaments were carried out to verify the results.The band structure of chiral monocellular structures of the four ligaments was studied,and the position of band gaps and the change of band gaps with the geometric configuration were obtained.With the increase of configuration ratio,the band gap tends to be low frequency and the width of the band gap becomes larger.Compared with other chiral structures,the chiral structures with a configuration ratio of 0.62 have very good low-frequency band gap characteristics.The attenuation of elastic waves in chiral structures of four ligaments with different periods and configurations was studied.With the increase of the number of cycles in the direction of wave propagation,the frequency response ratio becomes smaller and smaller,and the attenuation effect of elastic wave becomes more significant.In particular,the chiral structure with a configuration ratio of 0.62 showed a wide band gap at low frequencies.The accuracy of the above numerical simulation was verified by vibration reduction tests.With the increase of configuration ratio,the band gap becomes wider.The chiral structure with a configuration ratio of 0.62 has better vibration reduction effect at low frequency.The variation law of vibration transmission characteristics is consistent with the numerical simulation,which verifies the accuracy of the numerical simulation.