THERMAL BENDING ASSOCIATED WITH HEAT-CONDUCTION BY HOLOGRAPHIC-INTERFEROMETRY

An experimental technique using real-time holographic interferometry c ombined with digitized image processing has been developed to measure the thermal diffusivity of polymers. This technique uses a cantilever beam or an annular disk with one side subjected to a pulse of radiant energy from a photographic flash. The resulting thermally induced defl ection is measured by holographic interferometry. The observed deflect ion is due to a resultant thermal moment induced by a temperature grad ient through the thickness. As time goes on, the heat conducts from th e exposed surface through the thickness, resulting in a decrease of th e bending moment and transverse deflection. It is shown that the defle ction is proportional to the thermal moment, and the thermal diffusivi ty can be retrieved by moment analysis without deriving the analytical solution to the thermomechanical problem.