Experimental research of carbon fiber filament’s fracture toughness based on focus iron beam

The defects were precisely etched on the carbon fiber T300 and T800 by the focus iron beam (FIB) in order to analysis the fracture toughness of carbon fiber filaments. The tensile strengths of different filaments were obtained through single filament tensile experiment, and fracture sections were observed by SEM, the fracture toughness K_IC were estimated based on the strength-mirror method and Griffith theory. The results show that the value of K_IC of T300 carbon fiber filament is 1.32 MPa·m^1/2, whose error is less than 10% compared with the result of reference(1.25 MPa·m^1/2 ).