A vibration-reduction pipe clamp with piecewise stiffness

Pipe clamps are used widely for constraining pipes with relatively large sizes in aircraft. However, traditional clamps have large linear restraint stiffness and unsatisfactory vibration control effect. A pipe clamp model with piecewise-linear stiffness is proposed for the first time to improve vibration reduction ability. The mathematical model for the vibration of an aircraft fluid-conveying pipe constrained by two novel piecewise clamps is established. The left end of this pipe is subjected to a harmonic displacement excitation. The governing equations of the forced and natural vibrations are discretized by the Galerkin truncation method. The dynamics responses of the pipe are numerically calculated via the Runge-Kutta method and verified via the harmonic balance method. The effects of the parameters of the piecewise clamp on the dynamics responses of the pipe are explored. The vibration control performance of the piecewise clamp is compared with that of the traditional clamp and the linear clamp without piecewise stiffness. The new clamp with piecewise stiffness has a significantly higher vibration attenuation efficiency than the other two kinds of clamps. The piecewise stiffness characteristics of the novel clamp enable it to effectively control pipe vibrations even under strong excitation. At last, the forced vibration experiments are conducted. The superior vibration attenuation ability of the piecewise clamp is testified. This research can guide the design and mathematical modelling of the new pipe clamp with piecewise stiffness. It also provides novel insights into nonlinear vibration control for pipes.