Active thermography as a quantitative method for non-destructive evaluation of porous carbon fiber reinforced polymers

In this work active thermography was successfully applied as a quantitative method for the non-destructive evaluation of porosity in carbon fiber reinforced polymers. Results showed that not only the level of porosity, but also the shape of the pores strongly influences the active thermography results, in particular the measured thermal diffusivity. In an experiment the shape of the pores was obtained by means of X-ray computed tomography. Based on this microstructural information, the “dethermalization theory” can be deduced as the most effective thermal diffusivity model with respect to quantitative porosity determination. Furthermore, the obtained experimental data on active thermography correspond to measurements made using ultrasonic testing with respect to the influence of pore shapes.

► Active thermography is used for quantitative evaluation of porosity in CFRP.
► The pore morphology is obtained by means of X-ray computed tomography.
► The shape of the pores strongly influences the measured thermal diffusivity.
► The "Dethermalization Theory" can be deduced as the most effective thermal diffusivity model.
► Ultrasonic damping coefficient and thermal diffusivity show a linear dependency.