Numerical modeling of probe velocity effects for electromagnetic NDE

Velocity Effects and their Minimization in MFL Inspection of Pipelines — A Numerical Study

“…For axisymmetric geometries, discussed in this paper, the governing equation reduces to: (2) It is found that among the several time stepping algorithms used to solve the above non-selfadjoint equation, Leismann-Frind's method [5] provides a better solution, in terms of the overall considerations of accuracy and stability, for EM NDT applications. …”

Application of state-of-the-art FEM techniques to magnetostatic NDE

“…Several time step methods are available to solve Equation 4.2, including Donea's method [38], Zienkiewicz's method [39] and the Leismann-Frind method [37]. A detailed analysis of the comparative advantages of these methods when applied to a moving probe problem is presented in [40], and is beyond the scope of this dissertation.…”

“…It has been show in [40] that the Leismann-Frind method offers superior results in terms of overall considerations of accuracy and stability for electromagnetic NDE applications. This dissertation limits itself to the application of the Leismann-Frind method to the modeling of MFL inspection of pipelines, to the axisymmetric Ccise, and its extension for the 3D Ccise (Chapter 7).…”

“…Comparison of the values of the axial component of the flux density under the polesThe code is also used to demonstrate the differences between transient analysis and steady-state analysis. Reference[40] shows that the results obtained with the upwinding technique matched those from the Leismann-Frind method, if the tran sients at each time step in the Leismann-Frind method were allowed to die away, by iterating at each time step until convergence was reached. Using this observation, the difference between the upwinding technique and the transient analysis approach are shown inFigures 4.8 -4.10.…”

Remote field eddy current probes for the detection of stress corrosion cracks in transmission pipelines

“…On the other hand the motion-induced currents are oriented circumferentially and they are orthogonal to axially oriented SCC as illustrated in figure 1.5. Detection of the interaction between the circumferentially oriented currents and axially oriented cracks constitutes the principle of the current perturbation method [12], [13]. Current perturbation has also been studied as a candidate technique for SCC detection.…”