Abstract
The failure process of mode II delamination fracture is studied on the basis of the microscopic matrix failure modes (microcracks and hackles) as well as fracture mechanics principles. The crack tip matrix stresses leading to delamination is analysed by examining an adhesive bond with a crack analogous to a delamination crack in the resin layer of a composite. Such crack tip stresses induce matrix microcracks involving two major events: (a) single microcrack initiation and (b) development of multiple microcracks with regular spacing. The microcrack initiation shear stress τ* is found by the use of fracture mechanics to be related to certain resin properties (shear modulus G and mode I fracture toughness GIC) and microcrack length of the order of the resin layer thickness t (related to resin content).
The more or less regular microcrack spacing S deduced from shear lag considerations can be related to resin properties GIC, G, τy (resin yield strength) and t. The multiple microcracks reduce the effective resin modulus and strongly affect the subsequent microcrack coalescence process. As a result of the detailed analysis of the failure process, mode II laminate fracture toughness GIIC can be quantitatively expressed as a function of resin GIC and (τ2y/G). The failure process modelled is used to interpret the mode II delamination behaviour of several carbon/epoxy systems studied here and that reported in the literature. This study reveals the critical importance of resin fracture (GIC related) and deformation (yielding) mechanisms in controlling mode II delamination resistance of laminated composites.
Similar content being viewed by others
References
M.F. Hibbs and W. L. Bradley, “Correlations Between Micromechanical Failure Processes and the Delamination Toughness of Graphite/Epoxy Systems”, ASTP-948, (American Society for Testing and Materials, Philadelphia PA, 1987) p. 68.
L. Acran, M. Acran, and I. M. Daniel, “SEM Fractography of Pure and Mixed Mode Interlaminar Fractures in Graphite/Epoxy Composites”, ASTM STP-948, (American Society for Testing and Materials, Philadelphia PA, 1987) pp. 41–67.
B. W. Smith and R. A. Grove, “Determination of Crack Propagation Directions in Graphite/Epoxy Structures”, ASTM STP-948 (American Society for Testing and Materials, Philadelphia PA, 1987) pp. 154–173.
A. J. Russel, Polymer Compos 8 (1987) 342.
P. Davies and F. X. de Charentenay, in Proceedings of 6th International Conference on Composite Materials (ICCM-VI), London, July 20–24, 1987, (Elsevier, London, 1987) p. 3.284.
A. J. Russel and K. N. Street, in “Moisture and Temperature Effect on the Mixed Mode Delamination Fracture of Unidirectional Graphite/Epoxy, edited by W. S. Johnson, ASTM STP 876, (American Society for Testing and Materials, Philadelphia PA, 1985) pp. 349–370.
G. B. Murri and T. K. O'Brien, in Proceedings of the 26th AIAA/ASME/AHS Conferences on Structures, Structural Dynamics and Materials, Orlando, FL, April 15–17, 1987 (American Institute of Aeronautics and Astronautics (AIAA), New York, 1985) p. 172.
L. A. Carlsson, J. W. Gillespie and B. R. Trethewey, J. Reinf. Plastics 5 (1987) 170.
S. M. Lee, J. Mater. Sci. 19 (1984) 2278.
Idem, Polm. Engng. Sci. 27 (1987) 77.
Idem, “Fracture Mechanism of Delamination Fracture”, edited by J. D. Whitcomb, ASTM STP-972 (American Society for Testing and Materials, Philadelphia PA, 1988) pp. 356–365.
A. Parvizi, K. W. Garrett and J. E. Bailey, J. Mater. Sci. 13 (1978) 195.
A. Parvizi and J. E. Bailey, ibid. 13 (1978) 2131.
J. E. Bailey, P. T. Curtis and A. Parvizi, Proc. Roy. Soc. London A 366 (1979) 599.
D. Broek, “Elementary Engineering Fracture Mechanics”, (Martinus Nijhoff Publishers, The Hague, 1983).
H.-J. Sue, R. E. Jones and E. I. Garcia-Meiten, J. Mater. Sci. 28 (1993) 6381.
E. I. Garcia-Meitin and H.-J. Sue, Polym. Compos. 15 (1994) 165.
S. Lee and R. Schile, J. Mater. Sci. 17 (1982) 2066.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
LEE, S.M. Mode II delamination failure mechanisms of polymer matrix composites. Journal of Materials Science 32, 1287–1295 (1997). https://doi.org/10.1023/A:1018552506085
Published:
Issue Date:
DOI: https://doi.org/10.1023/A:1018552506085