FINITE ELEMENT ANALYSIS OF GUIDED WAVE PROPAGATION THROUGH DEFECT FREE PIPE BENDS

Abstract

This report focuses on understanding the propagation of ultrasonic guided waves through pipe bends. ANSYS 18.1 has been used to develop the geometry of straight pipe during the initial phase which is then extended to pipe bends. Nodal force is first applied tangentially in both the cases to obtain the displacement plots at various nodes downstream in order to determine the most suitable node for further analysis. Nodal displacement is applied in axial direction on all nodes on the circumference of the free face and displacements are again calculated. The displacement plots that are obtained are then analyzed using MATLAB. The group velocities and mode shapes are calculated by isolating the lobes in the displacement signal and then comparing the displacement of the nodes to check with which mode shape it corresponds to. An attempt has been made to find the dispersion curves. The First symmetric and Anti-symmetric mode shapes are clearly identifiable i.e. S0 and A0 and their corresponding velocities have been calculated. The simulations have been done for a comparatively coarse mesh size as the computation effort increases significantly with refinement of mesh