A New Technique for Thermal Nondestructive Testing by Means of Local Thermal Pulse

A new thermographic nondestructive testing technique employing local spot heating pulse is proposed and described. In a homogeneous and defect-free sample heating forms a radially symmetric thermal wave registered by a thermovision camera. An image data processing algorithm allowing the thermal conduction and temperature diffusivity of materials to be determined with an accuracy of about 2-3% has been developed and tested. Sample defects and inhomogeneities distort the circular shape of isotherms on the surface of the test object. The amplitude and shape of such distortions can serve as defect tracers. The proposed non-stationary thermal field data processing algorithm can be used to determine the location and geometry of defects on both the visible and hidden surfaces of the examined shell.