Magnetic effects of compressional stress at low field intensities

Toroidal, laminated cores of several important magnetic materials were tested for the low-field-intensity magnetic properties at compressional stresses ranging from 0 to 500 pounds per square inch (psi). The compressional stress was applied in a direction perpendicular to the plane of the laminations and perpendicular to the direction of the magnetic field, thereby simulating the binding of magnetic laminations in transformers, electric motors, servo components, etc. The materials tested were hydrogen-annealed specimens of 3.5 per cent (%) and 6.4% silicon-iron, 81% and 90% nickel-iron, 4¿79 and 5¿79 moly-permalloy, and hydrogen- and air-annealed specimens of AEM-4750, 12 Alfenol, and 16 Alfenol.