Delamination Fracture of Multidirectional Carbon-Fiber/Epoxy Composites under Mode I,Mode II and Mixed-Mode I/II Loading

Abstract

The purpose of the present study was to characterize the delamination fracture of continuous carbon fiber/epoxy multidirectional-laminates under Mode I, Mode II and Mixed-Mode I/II loading conditions. The present study considers the variation of the interlaminar failure energy, G _C, with the extent of crack jumping, and ensuing fiber bridging, which arises during the growth of the delamination in the multidirectional-laminates under the various modes of loading. The main type of laminate which was studied was a multidirectional fiber composite prepared from 24 ply lay-ups of (-45°/0°/+45°)_2S (+45°/0°/-45°)_2S. The initial delamination was located at the +45°/-45° mid-plane of the specimen. It has been found that when the values of the interlaminar fracture energy, G _c, are ascertained as a function of the length of the propagating crack, a, then very complex relationships are observed. This was the case for all the different modes of loading, and these observations reflected the complex failure paths which occurred as the delamination propagated through the multidirectional fiber composites. It was, however, possible to define clearly the onset of crack initiation. These results also revealed that the values for the interlaminar fracture energy, G _C-(initiation), at crack initiation for the (-45°/O°/+45°)_2S (+45°/O°/-45°)_2S multidirectional laminates were always significantly greater than that for the corresponding unidirectional (i.e., 0°/0°) laminates.

Keywords

delamination fracture fiber bridging fracture mechanics interlaminar fracture energy modes of failure multidirectional laminates

Get full access to this article

View all access options for this article.

References

1. P. Davies and M. L. Benzeggagh , "Interlaminar Mode-I Fracture Testing." Application of Fracture Mechanics to Composite Materials, edited by K. Friedrich , Composite Materials Series Vol. 6, Elsevier Science Publishers B. V. (1989) pp. 81-157.

2. X. N. Huang and D. Hull , "Effects of Fibre Bridging on GIC of a Unidirectional Glass/Epoxy Composites," Composites Science and Technology, 35 (1989) pp. 283-299.

3. W. L. Bradley , "Relationship of Matrix Toughness to Interlaminar Fracture Toughness," Application of Fracture Mechanics to Composite Materials, edited by K. Friedrich , Composite Materials Series Vol. 6, Elsevier Science Publishers B. V. (1989) pp. 159-187.

4. P. Davies , C. Moulin , H. H. Kausch and M. Fischer , "Measurement of GIC and GIIC in Carbon/Epoxy Composites," Composites Science and Technology, 39 (1990) pp. 193-205.

5. S. Hashemi , A. J. Kinloch and J. G. Williams , "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," Journal of Composite Materials, 24 (1990) pp. 918-956.

6. idem , "Mechanics and Mechanisms of Delamination in a Poly(ether sulphone)-Fibre Composites," Composites Science and Technology, 37 (1990) pp. 429-462.

7. idem , "The Analysis of Interlaminar Fracture in Uniaxial Fibre-Polymer Composites," Proc. Royal Soc. London, A427 (1990) pp. 173-199.

8. A. J. Kinloch , Y. Wang , J. G. Williams and P. Yayla , "The Mixed-Mode Delamination of Fibre Composite Materials," Composites Science and Technology, 47 (1993) pp. 225-237.

9. J. G. Williams , "Large Displacement and End Block Effects in the `DCB' Interlaminar Test in Modes I and II, Journal of Composite Materials, 21 (1987) pp. 330-347.

10.

10. idem , "Fracture Mechanics of Anisotropic Materials," Application of Fracture Mechanics to Composite Materials, edited by K. Friedrich , Composite Materials Series Vol. 6, Elsevier Science Publishers B. V. (1989) pp. 3-38.

11.

11. R. A. Jurf and R. B. Pipes , "Interlaminar Fracture of Composite Materials," Journal of Composite Materials, 16 (1982) 386-395.

12.

12. H. Chai , "Bond Thickness Effect in Adhesive Joints and Its Significance for Mode I Interlaminar Fracture of Composites," Composite Materials: Testing and Design, edited by J. M. Whitney , ASTM STP 893 (1986) pp. 209-231.

13.

13. L. A. Carlsson and J. W. Gillespie Jr. , "Mode II Interlaminar Fracture of Composites," ibid. (1989) pp. 113-157.

14.

14. Y. Wang and J. G. Williams , "Corrections for Mode II Fracture Toughness Specimens of Composite Materials," Composites Science and Technology, 43 (1992) pp. 251-256.

15.

15. C. Corleto and W. L. Bradley , "Mode II Delamination of Unidirectional Graphite/Epoxy Composites," Composite Materials: Fatigue and Fracture, edited by P. A. Lagau , ASTM STP948, (1998) pp. 201-222.

16.

16. idem , "Mixed-Mode Fracture in Fibre-Polymer Composite Laminates," Composite Materials: Fatigue and Fracture, edited by T. K. O'Brien , ASTM STP 1110 (1991) pp. 143-168.

17.

17. S. N. Chatterjee , W. A. Dick and R. B. Pipes , "Mixed-Mode Delamination in Laminated Composites," Composites Science and Technology, 25 (1986) pp. 49-67.

18.

18. M. Charalambides , A. J. Kinloch , Y. Wang and J. G. Williams , "On the Analysis of Mixed-Mode Failure," International Journal of Fracture, 54 (1992) pp. 269-291.

19.

19. D. L. Hunston , R. J. Moulton , N. J. Johnston and W. D. Bascom , "Matrix Effects in Composite Delamination: Mode I Fracture Aspects," Toughened Composites edited by N. L. Johnston , ASTM STP 937 (1987) pp. 74-94.

20.

20. B. D. Davidson , R. Kruger and M. Kong . "Three Dimensional Analysis and Resulting Design Recommendations for Unidirectional and Multidirectional Flexure Tests," J. Composite Materials, 29 (1995) 2108-2133.

21.

21. J. J. Ploaha , B. D. Davidson , R. C. Hudson and A. Pieracci , "Effects of Mode Ratio, Ply Orientation and Precracking on the Delamination Toughness of a Laminated Composite," J. Reinforced Plastics and Composites, 15 (1996) pp. 141-173.

22.

22. B. D. Davidson , C. S. Altonen and J. J. Polaha , "Effects of Stacking Sequence on Delamination Toughness and Delamination Growth Behaviour in Composite End-Notched Flexure Specimens," Composite Materials: Testing and Design, edited by R. B. Deo and C. R. Saff , ASTM STP 1274 (1996) pp. 393-413.

23.

23. C. T. Sun and S. Zheng , "Delamination Characteristics of Double-Cantilever Beam and End-Notched Flexure Composite Specimens," Composites Science and Technology, 56 (1996) 451-459.

24.

24. D. J. Nicholls and J. P. Gallagher , "Determination of GIC in Angle Ply Composites Using a Cantilever Beam Test Method," Journal of Reinforced Plastics and Composites, 2 (1983) pp. 2-17.

25.

25. H. Chai , "The Characterization of Mode I Delamination Failure in Non-Woven, Multidirectional Laminates," Composites, 15 (1984) pp. 277-290.

26.

26. P. Robinson and D. Q. Song , "A Modified DCB Specimens for Mode I Testing of Multidirectional Laminates," Journal of Composite Materials, 26 (1992) pp. 1554-1577.

27.

27. A. Laksimi , M. L. Benzeggagh , G. Jing , M. Hecini and J. M. Roelandt , "Mode I Interlaminar Fracture of Symmetrical Cross-Ply Composites," Composites Science and Technology, 41 (1991) pp. 147-164.

28.

28. ASTM , "Standard Test Method for Mode I Interlaminar Fracture Toughness of Unidirectional Fiber-Reinforced Polymer Matrix Composites," D 5528-94a (1994).

29.

29. W. L. Bradley , C. R. Corleto and D. P. Goetz , "Fracture Physics of Delamination in Composite Materials," AFOSR-TR-88-0020 (1987).

30.

30. B. R. K. Blackman , J. P. Dear , A. J. Kinloch , H. MacGillivray , Y. Wang , J. G. Williams and P. Yayla , "The Failure of Fibre Composites and Adhesively Bonded Joints under High Rates of Test: Part III," Journal of Materials Science, 31 (1996) pp. 4467-4477.

31.

31. B. R. K. Blackman , J. P. Dear , A. J. Kinloch , H. MacGillivray , Y. Wang , J. G. Williams and P. Yayla , "The Failure of Fibre Composites and Adhesively Bonded Joints under High Rates of Test: Part I," Journal of Materials Science, 30 (1995) pp. 5885-5900.