CRACK CLOSURE AND FIBRE BRIDGING CONTRIBUTION IN THE STRESSRATIO EFFECT ON DELAMINATION GROWTH UNDER FATIGUE

  • Sakhi Jan Department of Mechanical Engineering, Faculty of Engineering and Technology, International Islamic University Islamabad Pakistan,
Keywords: Stress ratio effect, Fibre bridging, Crack closure, Mode I fatigue delamination growth

Abstract

The objective of this paper is to investigate the contribution/role of the crack closure and the fibre bridging effects
in stress-ratio influence in mode I delamination growth in carbon/epoxy composite laminates. The crack closure effect
has been assessed by the identification of the non-linearity in the compliance curve of the double cantilever test
specimen after the delamination extension. The effect of fibre bridging was investigated by cutting the bridging fibres
during fatigue delamination. The fatigue test data was process using fracture mechanics principles. The delamination
growth rate in laminates was characterized using approach of strain energy release rate. The results of the experiments
of fatigue delamination growth with bridging fibres and un-bridged fibres have been compared for different
fatigue stress-ratios. The results show that crack closure only occurs at lower stress ratios. Fibre bridging does not
affect the stress ratio however the crack rate was decreased in this case.

References

1. Brunner, A. J., Blackman, B. R. K., & Davies, P.
(2008). “A status report on delamination resistance
testing of polymer–matrix composites”. Engineering
Fracture Mechanics, 75(9), 2779-2794.
2. Tanka, H., Tanaka, K., (1997) “Stress ratio effect on
mode II propagation of interlaminar fatigue cracks
in graphite/epoxy composites”. composite materials:
fatgue and fracture 6, ASTM STP 1285, p. 16.
3. Schon, J., (2000) “A Model of fatigue Delamination
in Composites”. Composite Science and Technology,
60: p. 553-558.
4. J. Andersons, M.H.b.a.S.O., (2004) “Empirical model
for stress ratio effect on fatigue delamination growth
rate in composite laminates”. International Journal
of Fatigue,. 26(6): p. 7.
5. Ritchie, R.O., (1988) “Mechanisms of Fatigue Crack
Propagation in Metals, Ceramics and Composites:
Role of Crack Tip Shielding”. Material Sience and
Engineering, A103: p. 15-28.
6. Ritchie, R. O. (1999). Mechanisms of fatigue-crack
propagation in ductile and brittle solids. International
journal of Fracture, 100(1), 55-83.
7. Standard Test Method for Mode I Interlaminar
fracture toughness of unidirectional Fiber-Reinforced
Polymer Matrix Composites, (2007) ASTM D5528-01.
8. Rans, C., Alderliesten, R., & Benedictus, R. (2011).
“Misinterpreting the results: How similitude can
improve our understanding of fatigue delamination
growth”. Composites Science and Technology, 71(2),
230-238.
9. Hojo M., Tanaka K., Gustafson C-G., Hayashi R.,(
1987) “Effect of stress ratio on near-threshold
propagation of delamination fatigue cracks in unidirectional
CFRP”. Compos Sci Technol, 29: p. 19.
10. Elber W.,( 1971) “The significance of Crack
Closure”. ASTM STP 486, Philadelphia., p. 230-242.
11. Martin Roderick H, M.B.G.,( 1990) “Characterization
of Mode I and Mode II Delamination Growth
and Thresholds in AS4/PEEK Composites”.
CompositeTesting and Design. ASTM: Philadelphia.
p. 19.
12. Hwang W., Han KS.,( 1989) “Interlaminar Frcature
Behaviour and fiber bridging of glass/epoxy
Composite Under Mode I Static and Cyclic
Loadings”. Journal of Composite Materials, 23.
13. XIAO-ZHI HU, Y.-W.M.,( 1992) “General Method for
Determination of Crack-Interface Bridging Stresses”.
Journal of Material Sciencec, 27: p. 3502-3510.
14. Yao, Liaojun, et al. (2016). “Stress ratio dependence
of fibre bridging significance in mode I fatigue delamination
growth of composite laminates.” Composites
Part A: Applied Science and Manufacturing
15. Alderliesten, R. C. (2016) “How proper similitudeand plasticity in fatigue.” International Journal of
Fatigue 82, 263-273.
16. Sarfarazi, Vahab, and Hadi Haeri. (2016) “A review
of experimental and numerical investigations about
crack propagation.” Computers and Concrete 18.2
,235-266.
17. Zhao, Libin, et al. (2016) “A novel interpretation
of fatigue delamination growth behavior in CFRP
multidirectional laminates.” Composites Science and
Technology 133 :79-88.
18. Asghar, W., et al., (2017) “Investigation of fatigue
crack growth rate in CARALL, ARALL and
GLARE.” Fatigue & Fracture of Engineering
Materials & Structures.
19. Erkkilä, Anna-Leena, Tero Tuovinen, and Matti Kurki.
(2016) “A review of the analytical and numerical
modeling of composites.” Reports of the Department
of Mathematical Information Technology. Series B,
Scientific computing 2016, no. 1.
Published
2017-11-20