Nondestructive Evaluation of Fiber Composite Laminates by Thermoelastic Emission

Abstract

During the rapid cyclic loading of a structure (≥ .5 Hz), the cyclic variation of surface temperature can be measured with infrared radiometry. The temperature variation is related to the reversible, adlabatic deformation of the material. Adiabatic thermography differs from disslpative thermography, where temperature variations are associated primarily with dissipated energy rather than stored energy. The radiometer system used in the present investigation is capable of resolving local stresses that reflect global stress distributions and macroscopic variations in material properties, including flaws and damage. The present paper emphasizes fundamental aspects of the technique for the nondestructive evaluation of fiber-reinforced composite laminates.