Dynamic Behaviour of Flexible Silicone Tube Subjected to Pulsatile Flow

Abstract

Flexible Silicone tubes possess superior qualities such as higher corrosion resistance, purity, strength, and inertness compared to other flexible tubes. Hence, these tubes own broad applicability in medical applications as well as other industrial applications. An unsteady flow through the flexible tube can induce severe internal excitation, which results in the flow-induced vibrations. Such vibrations at resonance can cause severe damage to the structure. Concerning the flexible tubes used in sophisticated medical applications, it is imperative to eliminate the structural vibrations, as far as possible. The present study examines the dynamics of the silicone tube under internal excitation due to pulsatile flow. It includes the investigation of the effect of pre-stretch and mean flow velocity on the dynamic behaviour of flexible tube by conducting parametric studies using the operational modal analysis technique. The influence of the mean flow velocity in the flexible tube is a proportional variation in the magnitude of vibration concerning fluid flow rate. An advance in pre-stretch causes a decrease in sagging, and the tube tends to retrieve its original circular cylindrical shape. Owing to this, when the tube is excited due to internal pulsation, the difference between the magnitude of vibration in the horizontal and vertical plane at resonance condition reduces, and the natural frequencies at different planes nearly become equal at higher pre-stretch, where sagging is negligible. The study reveals that for flexible tubes, the tube vibration always stabilizes in an arbitrary plane under excitation due to pulsation. This investigation exhibits that impact hammer excitation is better than constrained external excitation to find the fundamental frequencies of the flexible tube conveying fluid.