NDE of porosity in CFRP by multiple thermographic techniques

Non Destructive Testing on aerospace components is continuously changing due to the developments in materials and manufacturing processes. Thermography, if compared with other methods is gaining a role that mainly depends on findings reliability. Furthermore, dedicated procedures to particular component-defects couples are devised using advanced tools. This paper is devoted to the identification of porosity anomalous level on composite structures by thermography. Porosity is normally investigated by ultrasound techniques that, on the other hand, under usual conditions, are not always able to distinguish voids from resin starved zones (which they are themselves defects under some circumstances). The continuous behaviour of this kind of defect makes ordinary controls very difficult. The thermal properties mapping evaluation of local diffusivity and effusivity is used for this purpose. Both measures are sensible to the principal thermal properties variation, but the combination allows increasing considerably reliability of the result. Experimental results obtained on a real aeronautic part in different experimental conditions are reported and compared with findings given, by Ultrasounds. Numerical modelling of the various conditions helps to select suitable heating devices. A principal goal is the fast testing of a whole component in a one shot. A significant time saving is added to an easier interpretation of data. Additional information are also gained at the same time as the thickness or internal materials changing.