Umudike Journal of Engineering and Technology

Vibration is a subject of primary concern to engineers as most engineering structures and machines experience it to some degree and their design generally requires consideration of their oscillatory behavior. Viscous materials strain linearly with time while elastic materials strain instantaneously when stretched and quickly return to their original state once the stress is removed. This paper investigated the free vibration of a viscoelastic pipe conveying an incompressible fluid.  The pipe was idealized as a viscoelastic beam, the governing differential equation for the lateral vibration of the structure adopted was of the Euler-Bernoullis method and the material property of the beam model used is Kelvin-Voigt viscoelastic constitutive relation. The equation was non-dimensionalized and solved using finite element analysis. Effects of different flow conditions on the natural frequencies of the structure were also investigated and their implications analyzed. Results reveal that, whereas, imaginary natural frequency decreases with viscoelasticity, real natural frequency actually increases with viscoelasticity. Critical velocity decreases with viscoelasticity for both imaginary and real situations. Imaginary and real natural frequencies, though had the same value initially, later increase with mass ratio. Real natural frequency increases with material damping but imaginary part has a reverse case.