Novel vibration self-attenuation design of drill-string-like pipes transporting fluid with the enhancement of acoustic black hole effect

Abstract

Drill pipe constitutes a critical element of the drill string, susceptible to failure due to fatigue crack or dynamic instability induced by external excitation and double-gyroscopic effects. This paper proposes a novel type of periodically drill-string-like pipe based on photonic crystal (PC) structure and enhanced acoustic black hole (ABH) effect. The pipe is formulated using the discrete equivalent method and a two-dimensional model of Timoshenko beam theory. Based on the spectral element method (SEM) in conjunction with the transfer matrix method (TMM), a fundamental principle in the study of periodic structures, the band structure, natural frequency, frequency response, and the wave energy distribution of the proposed structure are disclosed. We find the proposed drill-string-like pipe can form low-frequency and broadband band gaps (BGs) to achieve self-suppression characteristics. However, these BGs will decay rapidly with the acceleration of spinning motion. By wrapping a viscoelastic tape of small size at the junction of ABH-pipe cells, the kinetic energy gathered at the edge of the ABH-pipe cell is dissipated effectively, resulting in vibration reduction in the pass band between the second and third BGs. This characteristic further broadens the frequency band of vibration reduction and does not disappear with the increasing spinning speed. The vibration reduction performance of the designed structure under operational conditions is further substantiated through frequency response analysis under stochastic loading scenarios. Thus, the proposed pipes receive the effective vibration self-suppression in the wide spinning-speed range. This work proposes a novel idea for the vibration suppression by the cooperation of BG and structural damping and may provide a reference for the vibration control of drill-string-like pipes in the industry.