A computationally efficient hybrid model to study ultrasonic wave propagation in long pipes with defects

This paper introduces a hybrid simulation technique to model elastic waves propagation in long pipes with damages using through-transmission approach. This hybrid model provides an efficient computational framework that only uses finite element (FE) modeling for damaged section of the pipe and simulates the rest via an analytical approach. It remarkably reduces the time and computational power required for such simulations since no spatial discretization is required for intact section of the pipe. An analytical technique is used to model the wave scattering in intact and long section of the pipe while an FE approach is implemented for its cracked segment. The effects of non-axisymmetric defects are studied in short range distance measurements using the developed FE model to have a better understanding of mode conversion and scattering in the pipe. Prior to implementation of the hybrid model, a semi-hybrid simulation is employed to study the pipes with defects very close to the excitation point. Then, the general case of a long pipe with a crack is studied. One particular observation was that cracks that are closer to the excitation point have a greater influence on propagating waves and cause higher energy loss compared to the cracks far from excitation location.