Pulse Thermography 

PT Pulse Thermography – is an active technique of infrared thermography (IRT – see ‘What the Hec?!’, March 2011). Instead of passively looking at the thermal signature of a component, the component is heated (or cooled) with a pulse of heat (or by cooling). The infrared camera is then used to observe the heat flow over time within the component. The presence of a defect interrupts the flow of the heat, causing hot spots. Analysis of the heat flow and the images can provide information regarding the nature of the defect and its depth from the surface.

The input for the PT heat pulse can be generated by a number of different methods, including infrared lamps, flash lamps, heated wire, lasers or air jets. PT can be applied in three configurations: on to a point, which is then scanned over the surface; in a line, which again is scanned over the surface; and directly onto a wide surface area. It has the general benefits of IRT, being fast to apply, non-contacting and with a wide span of applications. The disadvantages of PT are the difficulty in obtaining a uniformity of the heat stimulation, the effect of radiant and convective losses and the ability to only detect defects that result in a measurable change in the heat flow.

PT can be used to detect such defects as metal corrosion, cracks, disbonding, impact damage in composites, delaminations and porosity.

For more information on the use of PT see:

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