Scattering of guided waves by circumferential cracks in steel pipes

A novel numerical procedure is presented in this paper to study wave scattering by circumferential cracks in steel pipes. The study is motivated by the need to develop a quantitative ultrasonic technique to characterize properties of cracks in pipes. By employing wave function expansion in axial direction and decomposing the problem into a symmetry problem and an anti-symmetry problem, a three-dimensional wave scattering problem is then reduced to two quasi-one-dimensional problems. This simplification greatly reduces the computational time. Numerical results for reflection and transmission coefficients of different incident wave modes are presented here for a steel pipe with cracks of arbitrary circumferential lengths and radial depths. They are shown to agree quite well with available experimental data.