Delamination fracture toughness of continuous glass-fiber/epoxy composites for structural applications
- 137 Downloads
This paper presents experimental results of delamination fracture toughness tests on glass-fiber/epoxy composites which are manufactured in a novel Compression Resin transfer molding (CRTM) process in comparison to the performance of a well-studied RTM reference process. The examined laminates are built out of six plies, with a plain weave fiber orientation. 90% of the fibers are in longitudinal direction and 10% are perpendicular woven in. The influence of the process regarding interlaminar fracture toughness is tested under pure mode I (DCB), pure mode II (ENF) and mixed mode loading (MMB). The aim of this study is to establish a semi-empirical criterion to derive the interlaminar fracture toughness of all mixed-mode ratios using the pure mode I or II loading fracture toughnesses. It has been found, that the materials performance for both processes are comparable, however the fracture behavior is strongly influenced by the fabric structure. The examination of the laminates polymer system showed a strong R-curve behavior for mode I and mode II loading. It was possible to establish a semi empirical criterion that shows good agreement with the experimental results.
KeywordsRTM Compression RTM Mixed mode Strain energy release rate
The authors gratefully acknowledge Dr. Raman Chaudhari for the manufacture of the RTM panels at the Fraunhofer ICT. They also appreciate the financial support from the KITe hyLITE innovation cluster funded by the Fraunhofer Gesellschaft, the Karlsruhe Institute of Technology and the state of Baden-Württemberg.
- 1.Friedrich K (ed) (1989) Application of fracture mechanics to composite materials. Elsevier Science Publishers B.V, AmsterdamGoogle Scholar
- 15.Alif N, Carlsson LA, Gillespie JWJ (1997) Mode I, Mode II, and mixed mode interlaminar fracture of woven fabric carbon/epoxy. In: Hopper SJ (ed) Composite materials: testing and design, thirteenth volume, ASTM STP 1242, 13th edn. American Society for Testing and Materials, West Conhocken, pp 82–106CrossRefGoogle Scholar
- 18.Gong X-J, Benzeggagh M (1995) Mixed mode interlaminar fracture toughness of unidirectional glass/epoxy composite. In: Martin RH (ed) Composite materials: fatigue and fracture—fifth volume, ASTM STP 1230. American Society for Testing and Materials, Philadelphia, pp 100–123Google Scholar
- 19.DIN EN 6033 (1996) Determination of interlaminar fracture toughness energy-Mode I-GIC. Beuth-Verlag, BerlinGoogle Scholar
- 20.DIN EN 6034 (1996) Determination of interlaminar fracture toughness energy-Mode II-GIIC. Beuth-Verlag, BerlinGoogle Scholar
- 21.ASTM D 6671/D 6671M-06 (2006) Standard test method for mixed Mode I-Mode II interlaminar fracture toughness of unidirectional fiber reinforced polymer matrix composites. American Society for Testing and Materials, PhiladelphiaGoogle Scholar
- 24.Starke C, Beckert W, Lauke B (1996) Characterization of the delamination behaviour of composites under mode I- and mode II-loading. Mater Sci Eng Technol 27(2):80–89Google Scholar