Analysis of the effects of magnetic field on the induced stress in drilled plates

A drilled plate of ferromagnetic material suitably coupled by coils of enameled copper wire fed by a DC power supply to 30 V is considered in this paper. It is analyzed with finite element and later experiments are performed to validate the obtained results. After polishing the plate, two strain gauges for measuring the deformation along the x axis and along the z axis are installed. The values of strain are 5 μm/m in z direction and −2 μm/m in x direction. The experimental–numerical comparison shows that the laboratory results are lower than numerical, while signs and orders of magnitude are the same. It is concluded that the results of the FEM analysis can be considered acceptable because the orthogonality of the plane of the coils relative to the plane of the plate and because of the packing coefficient of copper. The position of the two coils is changed in order to found the optimal configuration which allows the maximum compressive stresses in the area around the hole; it is obtained using two coils joined (positioned above the hole) or using a single coil. Moreover numerical simulations are executed to verify the improvement of the fatigue life calculating the stress at the crack tip.