Detection and characterization of mechanical impact damage within multi-layer carbon fiber reinforced polymer (cfrp) laminate using passive thermography

Abstract

With the increasing application of CFRP laminate, there is an 'urgent need for the rapid, visual, and non-intrusive method to 'detect mechanical impact damage. Passive thermography has been proven 'as a promising alternative to traditional nondestructive test technique by 'imaging the surface temperature difference of target with the advantages of 'real-Time, non-intrusive, full-field, and visual 'results. Therefore, the aim of this paper is to 'characterize the impact damage types using passive thermography. To 'this goal, several specimens are subjected to impact test with 'different energies of 5, 10, 15, 20, '30, and 36 J and monitored by infrared camera. Then, active 'pulse thermography, SEM, and ultrasonic C-scanning are applied to 'detect the specimens respectively and the corresponding detection results 'are comparatively analyzed. On this basis, the impact damage 'types of CFRP are characterized. The obtained results show that 'different impact damage types occur under the different impact energies and 'can be characterized in the thermographic image. In detail, the 'matrix cracking, fiber rupture, and delamination can be characterized as 'hot spot with straight line shape along the fiber direction, hot spot 'with straight line shape perpendicular to the fiber direction and hot spot 'with irregular block shape respectively, which can facilitate the 'identification of impact damage mode and the evaluation of damage 'degree.