Experimental procedure to characterize the mode I dynamic fracture toughness of advanced epoxy resins

Epoxy resins are widely used in Carbon Fiber Reinforced Polymers (CFRPs) for the aeronautical industry. They must ensure cohesion in most of the structural composite parts incorporated into the modern manufactured aircrafts. So fracture properties of epoxy resins are essential features to resist critical decohesions in case of impact. Surprisingly however, there are few experimental studies dedicated to the dynamic fracture of these thermoset polymers. Therefore, this research aims at developing an experimental procedure to characterize the dynamic fracture toughness of epoxy resins during propagation. Since glassy polymers exhibit viscous fracture, the crack speed a is known for influencing the toughness of these materials. Then a strain gage method is proposed to determine the mode I dynamic energy release rate G ID for various crack speeds a. Thus an experimental set-up is defined to simultaneously implement strain gage measurement and high speed cinematography. Finally, preliminary results are briefly reported to demonstrate the method validity.