Ricerc@Sapienza

This study is devoted to the analysis of impact damage in composite samples by applying techniques of IR and
Terahertz imaging. The samples made of high-density homogeneous particleboards of sugarcane bagasse and
castor oil polyurethane resin were subjected to impacts with the energy from 5 to 30 J. The impact damage
defects were evaluated by applying one- and two-sided thermal non-destructive testing. Both the apparent
thermal effusivity and diffusivity were determined to analyse their relationship to impact energy. In the abovementioned
range of impact energies, the thermal effusivity varied from 5 to 18%, while the variations in thermal
diffusivity were from 4 to 24%. The algorithm of dynamic thermal tomography was used to demonstrate that
predominant subsurface cracking occurred at depths up to 1 mm. In addition, the defect areas were tested by
applying the Terahertz technique, whose results qualitatively matched the IR thermographic ones to show that
the damaged areas were larger than they appeared visually. However, both inspection techniques have revealed
no significant dependence of analysed parameters on impact energy. This is believed to prove that non-uniform
composite structure is the decisive factor in producing structural defects under impacting.