SYMPOSIA PAPER Published: 01 January 1995

Experimental Development of a Mixed-Mode Fatigue Delamination Criterion


Interlaminar fracture (delamination) is the dominant failure mechanism in most advanced composite materials. The resistance of a material system to delamination failure is generally quantified in terms of the interlaminar fracture toughness, Gc. The recently developed mixed-mode bending (MMB) test is unique in that it facilitates measurement of the fracture toughness Gc under any combination of mixed-mode loading from pure Mode I to pure Mode II. This makes it a very attractive technique for developing interlaminar fracture failure criteria. This paper reports on an application of the MMB test to fatigue loading for the generation of G versus N curves and identification of applicable mixed-mode fatigue failure laws. Fatigue results from unidirectional IM7/5260 carbon/bismaleimide and IM7/8320 carbon/thermoplastic specimens are presented for mode mixes varying from pure Mode I to pure Mode II. Static test results are also presented for both materials. The static and fatigue results indicate different mixed-mode failure laws for the two materials. Further, the effect of fatigue is shown to be both material and mode-mix dependent. All tests were conducted using displacement-controlled loading under room temperature dry conditions.

Author Information

Sriram, P
Wichita State University, Wichita, KS
Khourchid, Y
Wichita State University, Wichita, KS
Hooper, SJ
Wichita State University, Wichita, KS
Martin, RH
Analytical Services and Materials, Inc., Hampton, VA
Price: $25.00
Contact Sales
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Developed by Committee: D30
Pages: 3–18
DOI: 10.1520/STP14005S
ISBN-EB: 978-0-8031-5297-7
ISBN-13: 978-0-8031-2012-9