Phononic crystal pipe with periodically attached sleeves for vibration suppression

Abstract

Flexural vibration of pipes is a common problem in many practical engineering applications, which usually influences the operating state of the system or even causes damage of the equipment. In the present work, an easy-realized design of phononic crystal pipe is proposed to implement vibration suppression by directly upgrading the bare pipe with attached sleeves without replacing the original structure. Based on the mechanism of Bragg scattering, flexural wave bandgap could be obtained with the periodical changing in cross section of the sleeved pipe. Sleeve installation generates both added mass and added stiffness simultaneously, which leads to the parabolic variations in edge frequencies of the bandgap against sleeve dimensions. Asynchronous recovery of the two frequency loci makes the bandgap close up when the sleeve covers about half length of the unit cell. This feature is not observed in analyses of binary phononic crystal pipes. Equivalent models are proposed to discuss the predicted variations, and the singular dependence of closure of bandgap on sleeve length is theoretical explained. Experiments are carried out to validate the feasibility of attaching sleeves for flexural vibration suppression of pipes. The proposed design could effectively attenuate the vibration energy with the intended bandgap.