Numerical consideration of magnetic camera for quantitative nondestructive evaluation

It is important to estimate the distribution of intensity of a magnetic field for application of magnetic method to industrial nondestructive evaluation. Magnetic camera provides the distribution of a quantitative magnetic field with homogeneous lift-off and same spatial resolution. It consists of magnetic source, sensor head, magnetic lens, analog-digital converter, data processor, monitor, and each part corresponds to light source, CCD sensor, optical lens, processor, video recorder and monitor in digital video camera, respectively. Leakage magnetic flux near the crack on the specimen could be amplified by 3-dimensional magnetic fluid and zoom in and out of measurement area. This study introduces the numerical consideration of the effects of lens for focusing and concentrating of magnetic flux. The various parameters were magnetic permeability, shapes, sizes of the magnetic lens and measuring points of the magnetic flux. The result showed that the 3-dimensional magnetic fluid has sufficient lens effect for magnetic camera.