Viscous material-filled synthetic defects for vibrothermography

This paper describes a method to create viscous material-filled (VMF) synthetic defects for vibrothermography that, like cracks, delaminations, or disbonds, generate heat when exposed to vibration. Standard synthetic defects used in nondestructive evaluation, such as EDM notches and flat-bottom holes, are not suitable for vibrothermography since they do not generate a measurable amount of heat when vibrated. An array of viscous material-filled synthetic defects can be used to evaluate the vibration field in a structure due to a specific source to determine if local vibration amplitudes are sufficient to detect cracks or other defects in different locations in a structure. These synthetic defects can be used to resolve the long-standing problem of testing vibration coverage in a specimen for vibrothermography. Such defects can be manufactured in a wide range of materials and can aid in probability of detection studies.