Interlaminar fracture toughness of CFRP influenced by fibre surface treatment: Part 1. Experimental results

The bond between a fibre and the matrix is very important for the mechanical behaviour of CFRP. The quality of the fibre/matrix interface will influence the initiation and development of damage. This is certainly true for interlaminar fracture toughness. The present study is focused on the influence of the interface properties on the fracture toughness of CFRP. Carbon fibres with four different wet oxidative surface treatment levels have been investigated. The fibres were embedded in a thermoset resin and in a thermoplastic system. Mode I, mode II and mixed-mode tests were performed to determine critical strain-energy release rates. Results show an important increase in the fracture toughness initiation value with increasing fibre surface treatment level. For tests dominated by mode I loading, however, the propagation value can reach a maximum at intermediate treatment levels as a consequence of fibre bridging effects.

[1]  H. Schwartz,et al.  Effect of Fiber Coatings on Interlaminar Fracture Toughness of Composites , 1987 .

[2]  O. Ishai,et al.  Interlaminar fracture toughness and toughening of laminated composite materials: a review , 1989 .

[3]  2.5D fabrics for delamination resistant composite structures , 1994 .

[4]  J. G. Williams,et al.  The Effects of Geometry, Rate and Temperature on the Mode I, Mode II and Mixed-Mode I/II Interlaminar Fracture of Carbon-Fibre/Poly(ether-ether ketone) Composites , 1990 .

[5]  Shaw Ming Lee,et al.  Correlation between resin material variables and transverse cracking in composites , 1984 .

[6]  R. Keunings,et al.  Modelling of critical fibre length and interfacial debonding in the fragmentation testing of polymer composites , 1992 .

[7]  W. S. Johnson.  Delamination and Debonding of Materials , 1985 .

[8]  D. C. Phillips,et al.  The Damage Tolerance of High Performance Composites , 1981 .

[9]  J. Rice,et al.  Elementary engineering fracture mechanics , 1974 .

[10]  I. Verpoest,et al.  STUDY OF THE PARAMETERS WHICH CONTROL THE INTERFACE STRENGTH PROPERTIES IN CARBON EPOXY SYSTEMS , 1991 .

[11]  D. R. Moore,et al.  Round-robin interlaminar fracture testing of carbon-fibre-reinforced epoxy and PEEK composites , 1992 .

[12]  L. Ilcewicz,et al.  Mode I Interlaminar Fracture Toughness of Composites Using Slender Double Cantilevered Beam Specimens , 1985 .

[13]  C. Moulin,et al.  Measurement of GIc and GIIc in carbon:epoxy composites , 1990 .

[14]  D. R. Moore,et al.  Interlaminar fracture morphology of carbon fibre/PEEK composites , 1987 .

[15]  M. Wevers,et al.  INTERLAMINAR FRACTURE TOUGHNESS OF CFRP INFLUENCED BY FIBRE SURFACE TREATMENT: PART 2. MODELLING OF THE INTERFACE EFFECT , 1995 .

[16]  D. Hunston.  Composite Interlaminar Fracture: Effect of Matrix Fracture Energy , 1984 .

[17]  W. Bradley,et al.  Mode II Delamination Fracture Toughness of Unidirectional Graphite/Epoxy Composites , 1989 .

[18]  L. Drzal,et al.  Fiber-Matrix Adhesion and Its Effect on Composite Mechanical Properties: IV. Mode I and Mode II Fracture Toughness of Graphite/Epoxy Composites , 1992 .

[19]  M. Wevers,et al.  Influence of the Fibre-Matrix Interface On the Matrix Crack Development in Carbon-Epoxy Cross-Ply Laminates , 1989 .