Study of crack inversions utilizing dipole model of a crack and Hall element measurements

A method is proposed for computing the depth and width of simple surface cracks based on dipole model of a crack. Surface cracks with different widths cut mechanically in SS400 steel specimens are investigated. Hall voltage distributions are measured by a Hall element sliding on the specimen's surface along a line parallel to the direction of the applied magnetic field, perpendicular to the long axis of the crack, and halving its length. The performed crack inversions show that the depth of the crack can be determined with 2% error, provided, that the crack length and width are measured independently. When the crack width is unknown, the depth error is within 12%, but the width error can be as large as 30%