Analysis of a Nondestructive Evaluation Technique for Defect Characterization in Magnetic Materials Using Local Magnetic Measurements

Figure 3

(a) Computational domain covers the outer rectangle and is denoted by $\mathrm{\Omega }$. Copper windings are denoted by ${\mathrm{\Omega }}_i,\mathrm{\hspace{0.17em}\hspace{0.17em}}\mathrm{\hspace{0.17em}\hspace{0.17em}}i=1,\dots ,4$. The current in ${\mathrm{\Omega }}_1$ and ${\mathrm{\Omega }}_4$ flows in the opposite direction as in ${\mathrm{\Omega }}_2$ and ${\mathrm{\Omega }}_3$. The grey area denoted as ${\mathrm{\Omega }}_{\text{str}}$ is one and half steel strip without the air gap. The air gap is denoted by ${\mathrm{\Omega }}_{\text{ag}}$; its left boundary is at $x=\alpha$, and it has a width $\beta$ (see Figure 2). Finally, the yoke is denoted by ${\mathrm{\Omega }}_y$. Short vertical lines mark the positions of local measurements of the magnetic induction. (b) Non-linear material characteristic ${\nu }_{\text{steel}}(B)$ for the steel strips.

(a)

(b)