Active Thermal Testing of Impact Damage in 3D-Printed Composite Materials

Using the method of ultrasonic infrared thermography, it has been shown that 3D printing technology prevents cracking of the edges of access holes in composites during their machining. It is expedient to evaluate the impact strength of composites by the relative change in the thermophysical characteristics in the zones of impact damage, based on the assumption that a higher impact energy leads to the more developed defects and, accordingly, to the greater relative changes in thermal inertia and thermal diffusivity. The impact resistances of Kevlar and carbon fiber composite specimens, as well as their hybrid, have been compared. The highest impact resistance was demonstrated by a hybrid sample of Kevlar and carbon fiber composite, in which the change in thermal inertia and thermal diffusivity after an impact with an energy of 15 J was 4 and 8%, respectively, compared with 10 and 9% for the CFRP and 15 and 11% for the Kevlar.