  An algorithm is introduced for using electrical surface measurements to
detect and monitor cracks inside a two-dimensional conductive body. The
technique is based on transforming the probing functions of the classical
enclosure method by the Kelvin transform. The transform makes it possible to
use virtual discs for probing the interior of the body using electric
measurements performed on a flat surface. Theoretical results are presented to
enable probing of the full domain to create a profile indicating cracks in the
domain. Feasibility of the method is demonstrated with a simulated model of
attaching metal sheets together by resistance spot welding.
