Interlaminar fracture

Fig. 5. Interlaminar fracture toughness, for a number of thermosetting and thermoplastic composites (36,37). Open white bars represent glass-fiber composites shaded bars are for carbon fibers. The materials are A, polyester (unidirectional) B, vinyl ester (CSM = chopped strand mat) C, epoxy (R/BR1424) D, epoxy (T300/914) E, PPS F, PES and G, PEEK. To convert J/m to fdbf/in. multiply by 2100.

A number of amorphous thermoplastics are presently employed as matrices in long fiber composites, including polyethersulfone (PES), polysulfone (PSU), and polyetherimide (PEI). AH offer superior resistance to impact loading and higher interlaminar fracture toughnesses than do most epoxies. However, the amorphous nature of such polymers results in a lower solvent resistance, clearly a limitation if composites based on such polymers are to be used in aggressive environments. 

ISO 14130 1997 Fibre-reinforced plastic composites - Determination of apparent interlaminar shear strength by short-beam method ISO 15024 2001 Fibre-reinforced plastic composites - Determination of mode I interlaminar fracture toughness, GIC, for unidirectionally reinforced materials... 

Fig. 3.30. Schematic illustrations of Mode I interlaminar fracture test specimens (a) DCB specimen (b)...

The pure mode II interlaminar fracture testing can be performed using both the end notched flexure (ENF) specimen (Russell and Street, 1984, 1985) and the end loaded split (ELS) specimen (Corleto and Bradley, 1987 Prel et al.. 1989) (Fig 3.32). 

Fig. 3.33. CLS specimen for mixed mode interlaminar fracture tests.

ASTM D 5528 (1994). Mode I interlaminar fracture toughness of unidirectional fiber-reinforced polymer matrix composites. 

Davies, P. and Roulin. A. (1989). A standard for interlaminar fracture testing of composites. In Proc. ECCM 3, Developments in the Science and Technology of Composite Materials. (A.R. Bunsell, P. Lamicq and A. Massiah eds.), Elsevier Appl. Sci., London, pp. 419-424. 

Davies, P. Kausch, H.H., Williams, J.G. and 29 other researchers (1992). Round-robin interlaminar fracture testing of carbon fiber reinforced epoxy and PEEK composites. Composites Sci. Technol. 43, 129-136. 

Hashemi, S., Kinloch, A.J. and Williams, J.G. (1990b). The analysis of interlaminar fracture in uniaxial fiber polymer composites. Proc. Roy. Soc. Lond. A427, 173-199. 

O Brien, T.K. and Martin, R.H. (1992). Results of ASTM round robin testing for mode I interlaminar fracture toughness of composite materials, NASA TM 104222. 

Russell, A.J. and Street, K.N. (1984). Factors affecting the interlaminar fracture energy of graphite/epoxy laminates. In Proc. 4th Intern. Conf. on Composite Materials. (T. Hayashi, K. Kawata and S. Umekawa eds.), Japan Society of Composites Materials, Tokyo, p. 129. 

The increase in mode II interlaminar fracture toughness is even more significant than the mode 1 interlaminar fracture toughness. The similarity in the changes of magnitude of the mode II fracture toughness and the ILSS with regard to the level of... 

Summary of Mode I and Mode II interlaminar fracture toughness values for unidirectional carbon fiber 828 mPDA epoxy matrix composites with different fiber surface treatments ... 

Suzuki, Y., Maekawa, Z., Hamada, H., Yokoyama, A. and Sugihara, T. (1993). Influence of silane coupling agents on interlaminar fracture in glass fiber fabric reinforced unsaturated polyester laminates. J. Mater. Sci. 28, 1725-1723. 

IMPROVEMENT OF INTERLAMINAR FRACTURE TOUGHNESS WITH INTERFACE CONTROL... 

Effects of matrix materials on interlaminar fracture resistance... 

The first generation of resins developed for use in high performance carbon fiber composites emphasized high modulus and high glass transition temperature, Tg. Due to the low interlaminar fracture resistance of these resins, in particular under hot and wet conditions, a second generation of matrix materials has been developed with special focus on the resistance to interlaminar fracture of composites. 

Chapter 8. Improvement of interlaminar fracture toughness with interface control... 

Fig. 8.2. Composite mode I interlaminar fracture toughness, G[, as a function of respective neat resin toughness, G] ( ) Kim et al. (1992) (O) from Russell and Street (1987) ( ) toughened thermosets and ( ) thermoplasties from Hunston et al. (1987) (A) from Bradley (1989a) ( ) from Jordan and Bradley...

Fig. 8.3. In-situ scanning electron microphotographs of mode I interlaminar fracture of Hexed T6T145 carbon liber composites containing (a) 1155 unmodifted epoxy matrix, and (b) FIS5 rubber-modified epoxy matrix. Reprinted from Bradley (1989b), with kind permission from Hlsevier Seience-NL, Sarti burger hart straat 25, 1055 KV Amsterdam, Fhc Netherlands,...

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