Detection of open cavities (e.g. cracks) on the surface of a material based on the ability of certain liquids to penetrate and then bleed (rise to the surface) by capillarity
On ferromagnetic materials, spraying of magnetic powder which agglomerates (instead of being uniformly distributed) in defect areas (e.g. cracks, through cavities, etc.)
The material is penetrated by very short wavelength X-ray radiation, the variation in intensity collected makes it possible to detect internal defects
Transfer of an acoustic wave through a material, depending on the defects observed, part of the energy is reflected on a sensor (principle used in medical ultrasound
