Fatigue simulation of GFR composites in 3-point bending tests

• Type: Article in International Scientific Journal
• Date: 2005

Authors

Lima, AMV (Author) Other; António Torres Marques (Author) FEUP

Journal

Title: Science and Engineering of Composite Materials

Vol. 12

Pages: 159-165

ISSN: 0334-181X

Publisher: Walter De Gruyter

Indexing

ISI Web of Knowledge - 0 Citations

Scopus - 0 Citations

Other information

Authenticus ID: P-000-6QQ

Abstract (EN): In the present paper, we apply the critical element of Reifsnider's theory /1/, a cumulative damage model, to simulate the fatigue behavior of a fiberglass-epoxy composite. system, based on a quasi-unidirectional prepreg, in 3-point bending tests with a constant amplitude of strain. We studied a cross-ply [(0/90)(4)](S) laminate and a quasi-isotropic [(O/+/- 45/90)(2)](S) laminate. The fatigue tests were carried out according to NF T 51-120-3 and stress evolution was followed until the end of the test. As we believe that lamina properties are different if the lamina is an individual ply or when it is inside the laminate, we extracted the lamina properties from the multilayer laminates using a model proposed by Phifer /2/ for axial loading. in our study, we modified the Phifer model using laminate classical theory applied to bending loading, in order to relate the stiffness reduction evolution law of a subcritical element with the stiffness reduction evolution law of the laminate. This law was used in software developed by us, with the S-N curves of the 0 degrees plies and laminate classic theory, to simulate load evolution up to the end of the test, that is, up to the rupture of the 0 degrees ply near the neutral axis of the specimen. From the curves we can also obtain the S-N curves of the laminates. Alternatively, we have used another model based on the matrix cracking evolution with the number of cycles. As the stiffness reduction is mainly dependent on matrix cracking in the subcritical. plies, we measured its evolution with the cycle numbers for different stress levels. Then, we used a stiffness evolution law of the subcritical elements function of crack density developed by Smith and Ogin /3/. This law was also used in the software instead of the stiffness evolution law of the subcritical plies, when extracted from the laminate stiffness. The S-N curves obtained from both model approaches agreed very well with the experimental results. In addition, the curves of stress vs. number of cycles simulate very well the experimental curves for both models

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7