Transient response of a driver coil in transient eddy current testing

Transient response of a driver-pickup coil probe in transient eddy current testing

“…This approach accounts for all electromagnetic interactions arising in inductively coupled systems and, thus, addresses the feedback problem. The theory was applied to the simple case of a driver coil encircling a ferromagnetic conducting rod [17]. The coil's calculated response to a step excitation was in excellent agreement with experimental results.…”

“…Following the steps in [16,17], induced voltages ε 1 t ð Þ and ε 2 t ð Þ are expressed as the convolution of the system's impulse response with the as yet unknown time-dependent current functions i 1 t ð Þ and i 2 t ð Þ such that…”

“…Thus, electromagnetic field theory and circuit theory have been intuitively combined to provide a complete model of eddy current induction phenomena. In this work, the theory developed in [16,17] is extended to include a pickup coil. The coupled circuit equations, which describe the currents flowing in the driver and pickup, are formulated in terms of a conducting and ferromagnetic rod's impulse response using convolution theory, and solved by Fourier transform.…”

Pulsed Eddy Current Non-destructive Testing and Evaluation: A Review

“…Surface or pancake coils may be orientated either parallel or normal to the surface of the sample and they are used for both flat and curved samples. Encircling coils are generally used in the inspection of cylindrical elongated structures, such as hollow pipes and solid rods [10], [11]. Coils of this type form a circle around the diameter of the test object coaxially.…”

“…The method computes the time-domain electromagnetic response of the system and the results were validated by experimental data that display a very good agreement. Increasingly, a method for determining the electrical conductivity and the magnetic permeability that arises from the analytical solution for the ferromagnetic rod and encircling coils has been also suggested by Desjardins et al [11]. This is a good example of how modelling may enhance the use of PEC in NDT inspection.…”