An analytical method for dynamic analysis of fluid conveying viscoelastic pipes b

In this paper, applying the general form of the viscoelastic model, vibration characteristics of viscoelastic fluid conveying pipes are investigated. By considering various viscoelastic constitutive equations, the equation governing the motion of the fluid conveying pipes is obtained, and by introducing a new analytical method, the exact mode shapes of the system are derived. Then, the effect of various system parameters on the complex eigenvalues and the instability of kind divergence and flutter are studied. The results show that for a pipe with viscoelastic behavior, the natural frequencies decrease and at the higher modes, the divergence critical fluid velocity increases dramatically. As a new result, it is observed the viscoelastic fluid conveying pipes with certain values of viscoelastic parameters, can experience the flutter instability before the divergence one. In addition, because the viscoelastic behavior does not affect all the vibration mode shapes in the same manner, therefore, the coupled-mode flutter does not take place.