Characterizing Mode I Fatigue Delamination of Composite Materials

by Roderick H. Martin, Analytical Services and Materials, Hampton, United States,



Document Type: Proceeding Paper

Part of: Mechanics Computing in 1990's and Beyond

Abstract:

Evaluation of two techniques to characterize fatigue delamination using the double cantilever beam (DCB) specimen are presented. The two techniques were the delamination growth onset (G-N) method and the delamination growth the arrest (da/dN-G) method. Two glass/epoxy systems, S2/SP250 and S2/CE9000, were tested at R=0.1 and R=0.5. The values of strain energy release rate threshold, ΔG_Ith for no onset of delamination growth until one million cycles were compared with the values of ΔG_I at delamination arrest. The values of ΔG_I at delamination arrest were consistently higher than the values of ΔG_Ith. The ΔG_I results were normalized by the value of mode I Interlaminar fracture toughness at the corresponding Δa and gave values at delamination arrest closer to the ΔG_Ith/G_Ic values obtained from the G-N technique. However, this normalization does not represent a generic materials characterization technique and does not allow for delamination onset predictions at loads above the threshold.

Subject Headings: Materials characterization | Delaminating | Composite beams | Composite materials | Fatigue (material) | Construction materials | Material mechanics | Beams

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