Measurement of Magnetic Flux Density near Sheet under Uniaxial Stress

In order to utilize magnetoelastic interaction effect in ferromagnetic materials for measuring stress, it is preferable that measured value affected by the interaction is obtained independently of the detecting system. When a sheet is magnetized, magnetic flux density near the sheet is affected by the interaction, the value of which can be measured independently of the detecting system. A detecting system using Gauss meters is proposed to measure the relationship between B_b/B_a and uniaxial stress σ, where B_a and B_b are the magnetic flux densities near the back surface of the sheet and near the sheet surface, respectively. By conducting experiments which use various values of σ, magnetizing frequencies and low magnetic fields, it is shown that the system can detect the relationship sensitively, and that frequencies more sensitive to the relationship exist. Also, a method for evaluating the value of stress in the sheet independently of the detecting system is shown based on the results obtained.