Page 353 - Engineered Interfaces in Fiber Reinforced Composites

334 Engineered interfaces in fiber reinforced composites

Fig. 8.3. In-situ scanning electron microphotographs of mode I interlaminar fracture of Hexcel T6T145
carbon fiber composites containing (a) F155 unmodified epoxy matrix, and (b) F185 rubber-modified
epoxy matrix. Reprinted from Bradley (1989b), with kind permission from Elsevier Science-NL. Sara
burger hart straat 25, 1055 KV Amsterdam, The Netherlands.

debonding with limited crack tip non-linear deformation both in the transverse and
longitudinal directions. In contrast, the deformation zone for the rubber-modified
T6T145/F 185 system is very large, extending several fiber diameters beyond the resin
rich region between plies. It appears that the amount of resin ductility has controlled
the degree of crack tip blunting, which in combination with the stress redistribution
due to non-linear deformation determine the resistance to crack extension. A strong
fiber-matrix interfacial bond is essential to the occurrence of these mechanisms