Interlaminar Fracture Toughness Characterization of Unidirectional Carbon Fiber Composite (AS4/914 prepreg)

Viswamurthy , SR and Siva, M and Ramachandra, HV and Stanley , C Salem (2013) Interlaminar Fracture Toughness Characterization of Unidirectional Carbon Fiber Composite (AS4/914 prepreg). Technical Report. CSIR-NAL, CSIR-NAL, Bangalore.

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Vulnerability to delaminations is one of the major weaknesses of advanced laminated composite structures. Knowledge of a laminated composite material’s resistance to interlaminar fracture is useful for product development and material selection. Interlaminar fracture toughness is a measure of the material’s resistance for interlaminar crack/delamination growth and is known to be mode dependent. The scope of this study is to measure the interlaminar fracture toughness of unidirectional carbon fiber composite (AS4/914 prepreg system) under (a) Mode I loading, (b) Mode II loading, and (c) Combination of Mode I & Mode II loading. This report presents a detailed description of the tests and their results. Carbon fiber composite specimens from AS4/914 prepreg system processed by autoclave molding technique were tested as part of this study. The standard double cantilever beam test (ASTM D 5528) was followed for measuring pure Mode-I interlaminar fracture toughness. Since there is no standard test for pure Mode-II, two different test methods available in literature were attempted: 4-point bend end notched flexure test (4-ENF) and 3-point bend end notched flexure test (3-ENF). Fracture toughness data obtained from both mode-I and mode-II tests are compared with published data of other Carbon fiber composites used in the aerospace industry. The standard mixed mode bending test (ASTM D 6671) was followed for measurement of interlaminar fracture toughness under mixed mode-I mode-II loading. The fracture toughness contour showing the variation of fracture toughness with mode mixture is plotted and compared with other CFRP materials found in literature. In future, numerical simulations / finite element analyses can use this experimental data for prediction of delamination growth.

Item Type: Monograph (Technical Report)
Uncontrolled Keywords: Interlaminar fracture toughness; Mode I; Mode II; Mixed mode;
Subjects: CHEMISTRY AND MATERIALS > Composite Materials
ENGINEERING > Structural Mechanics
Depositing User: Dr. Viswamurthy S R
Date Deposited: 03 Jun 2013 10:22
Last Modified: 09 Oct 2015 06:10

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