Mode I Interlaminar Fracture Characterization of CFRP Composite Laminates

Abstract:

This study examines the deformation response of CFRP composites with preexisting delamination crack under Mode I loading. A DCB specimen is used in a series of Mode I interlaminar tests, each having a different initial delamination crack length. The 48-ply composite laminate has a symmetric ply sequence with 0/0 fiber orientation at the mid-plane. Apparent toughness is indicated by the composite specimen with a starter film insert, likely due to the presence of a neat pocket of resin at the front of the starter crack. The compliance of pre-delamination cracked specimens increases faster beyond the normalized delamination length, a/L of 0.68 due to effects of severe deflection of the longer DCB specimen arm. The critical energy release rate, G_IC = 0.5 N/mm is determined based on pre-cracked DCB specimens. Fractographic analysis revealed a smooth fracture plane that indicates interface delamination as the primary failure mode.

• Periodical: Advanced Materials Research (Volumes 488-489)
• Pages: 552-556
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.488-489.552
• Online since: March 2012
• Authors: S.S.R. Koloor, H. Hussin, M.N. Tamin
• Keywords: CFRP Composites, DCB Specimen, Interface Delamination, Mode-I Fracture

References

[1] ISO 14125, Fibre-reinforced plastic composites - Determination of flexural Properties, (1998).

[2] ASTM (D 5528 – 01), Standard Test Method for Mode I Interlaminar Fracture Toughness of Unidirectional Fiber-Reinforced Polymer Matrix Composites, Reapproved (2007).

DOI: 10.1520/d5528-01r07e02

[3] Davidson BD, Schapery RA, Effect of finite width on deflection and energy release rate of an orthotropic double cantilever specimen, J Compos Mater, 22, 640–56, (1988).

DOI: 10.1177/002199838802200704

[4] Johnson, W.S. and Mangalgari, P.D., Investigation of fiber bridging in double cantilever beam specimens, J. Composite Technology and Research, Vol. 9, pp.10-13, (1987).

[5] O'Brien, T. K., and Martin, R. H., Results of ASTM Round Robin Testing for Mode I Interlaminar Fracture Toughness of Composite Materials, Journal of Composites Technology and Research, Vol 15, No. 4, (1993).

DOI: 10.1520/ctr10379j

[6] S.S.R. Koloor, A. Abdul-Latif and M.N. Tamin, Mechanics of Composite Delamination under Flexural Loading, Key Engineering Materials Journal, Fracture and Strength of Solids VII, Trans Tech Publications, Switzerland, Vols. 462-463, pp.726-731, (2011).

DOI: 10.4028/www.scientific.net/kem.462-463.726

[7] Davila,  C. G., and P. P. Camanho, Analysis of the Effects of Residual Strains and Defects on Skin/Stiffener Debonding using Decohesion Elements, SDM Conference, Norfolk, VA, April 7–10, (2003).

DOI: 10.2514/6.2003-1465