Experimental Investigation of Progressive Damage and the Effect of Layup in Notched Tensile Tests

Abstract

The presence of subcritical damage in notched composites significantly affects the ultimate failure mode and strength. This article presents a detailed study of four different layups of E-glass/913 tested using a double-edge-notched specimen loaded in tension. For each layup three different in-plane dimensions are tested. Results are presented in terms of failure mode, strength, and subcritical damage development. Subcritical damage development is consistent between the layups and between scaled specimens of a single layup. Ultimate failure, however, shows some variations both with layup and size and this is examined in some detail. The trend of decreasing strength with increasing specimen size is observed for all cases except those where there is a change in failure mode between different size tests. The strengths are compared with predictions from two analytical techniques, which show some ability to achieve correlation across a subset of the test data. Correlation is not possible where variations in failure mode occur for a single layup.

Keywords

notched strength progressive damage layup effects tensile loading

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References

Whitney, J.M. and Nuismer, R.J. (1974). Stress Fracture Criteria for Laminated Composites Containing Stress Concentrations, Journal of Composite Materials, 8: 253–265.

Awerbuch, J. and Madhukar, M.S. (1985). Notched Strength of Composite Laminates: Predictions and Experiments – A Review, Journal of Reinforced Plastics and Composites, 4: 3–159.

Kortschot, M.T. and Beaumont, P.W.R. (1990). Damage Mechanics of Composite Materials I: Measurements of Damage Strength, Composites Science and Technology, 39(4): 289–301.

Coats, T.W. and Harris, C.E. (1999). A Progressive Damage Methodology for Residual Strength Predictions of Notched Composite Panels, Journal of Composite Materials, 33(23): 2193–2232.

Lagace, P.A. (1986). Notch Sensitivity and Stacking Sequence of Laminated Composites, In: Whitney, J.M. (ed.), Composite Materials: Testing and Design (Seventh Conference), ASTM STP 893, ASTM, Philadelphia, pp. 161–176.

Sun, C.T. and Zhou, S.G. (1988). Failure of Quasi-isotropic Composite Laminates with Free Edges, Journal of Reinforced Plastics and Composites, 7: 515–557.

Wisnom, M.R. and Chang, F.K. (2000). Modelling of Splitting and Delamination in Notched Cross-ply Laminates, Composites Science and Technology, 60(15): 2849–2856.

Liu, C.J. , Sterk, J.C. , Nijhof, A.H.J. and Marissen, R. (2002). Matrix-dominated Damage in Notched Cross-ply Composite Laminates: Experimental Observations, Applied Composite Materials, 9: 155–168.

Aymerich, F. , Mannu, M. and Priolo, P. (2002). Damage Mechanisms in Notched Graphite/Epoxy Laminates, In: Proceedings of American Society for Composites, 17th Annual Technical Conference, West Lafayette.

10.

Hallett, S.R. and Wisnom, M.R. (2005). Numerical Investigation of Progressive Damage and the Effect of Layup in Notched Tensile Tests, Journal of Composite Materials (in press).

11.

Soutis, C. (1994). Damage Tolerance of Open-hole CFRP Laminates Loaded in Compression, Composites Engineering, 4(3): 317–327.

12.

Wisnom, M.R. (1999). Size Effects in the Testing of Fibre-composite Materials, Composites Science and Technology, 59(13): 1937–1957.

13.

Towse, A. , Setchell, C. , Potter, K.D. , Clarke, A.B. , Macdonald, J.H.G. , Wisnom, M.R. and Adams, R.D. (2001). Use Experience with a Developmental General Purpose Non-contacting Extensometer with High Resolution, In: Nontraditional Methods of Sensing Stress, Strain, and Damage in Materials and Structures, ASTM STP 1323, pp. 36–51.

14.

Kashtalyan, M. and Soutis, C. (2000). Stiffness Degradation in Cross-ply Laminates Damaged by Transverse Cracking and Splitting, Composites: Part A, 31(4): 335–351.

15.

Floyd, A. , Vaziri, R. and Poursartip, A. (2003). Modelling Specimen Size Effect in Laminated Composites, In: Proceedings of the 14th International Conference on Composite Materials (ICCM14), San Diego.

16.

Nuismer, R.J. and Whitney, J.M. (1975). Uniaxial Failure of Composite Laminates Containing Stress Concentrations, In: Fracture Mechanics of Composites, ASTM STP 593, pp. 117–142.

17.

Wisnom, M.R. and Atkinson, J.W. (1997). Reduction in Tensile and Flexural Strength of Unidirectional Glass Fibre-epoxy with Increasing Specimen Size, Composite Structures, 38(1–4): 405–411.

18.

Vaidya, R.S. and Sun, C.T. (1997). Fracture Criterion for Notched Thin Composite Laminates, AIAA Journal, 35(2): 311–316.

19.

Takeda, N. and Ogihara, S. (1994). Initiation and Growth of Delamination from the Tips of Transverse Cracks in CFRP Cross-ply Laminates, Composites Science and Technology, 52(3): 309–318.

20.

Okabe, T. and Takeda, N. (2002). Size Effect on Tensile Strength of Unidirectional CFRP Composites – Experiment and Simulation, Composites Science and Technology, 62(15): 2053–2064.

21.

Wisnom, M.R. (2000). Modelling Progressive Fibre Failure with Size Effect, In: Proceedings of American Society for Composites, 15th Annual Technical Conference, Texas, pp. 639–648.

22.

Kongshavn, I. and Poursartip, A. (1999). Experimental Investigation of a Strain-softening Approach to Predicting Failure in Notched Fibre-reinforced Composite Laminates, Composites Science and Technology, 59(1): 29–40.