Figure 11 (a) and (b) below show the bottomside, geometry-only MFL signal and stress-only MFL signal for the modelled 8mm deep dent. In comparing Figure 11(a) with the experimental ‘geometry-only’ result for the 8mm deep large dent ( Figure 4, 8mm deep dent, post-anneal), an excellent correlation is observed. Figure 11(b)
indicates that the dent rim stresses lead to a distinctive shoulder peak in the signal. In comparing this with the
experimental results, we believe that this corresponds to the ‘stress shoulder peaks’ seen in pre-annealing MFL signals (see, for example Figure 4, pre-anneal, 3mm deep dent MFL signal).