The Influence of Orthotropy and Taper Angle on the Compressive Strength of Composite Laminates with Scarfed Holes

Abstract:

The residual strengths of laminated composites containing notches or holes depend on the characteristic dimension of the notches as well as the laminate properties. This paper presents an experimental and computational investigation of the effect of orthotropy as well as scarf notch angles on the compressive strength of composite laminates made of seven different stacking sequences with the number of plies ranging between 20 and 24. Specimens containing scarfed holes of different scarf angles (6° and 10°) and straight holes of two different diameters (3.175mm and 6.35mm) were tested for comparison. Experimental results of the compressive strengths, normalised by the respective un-notched compressive strength show that the extent of orthotropy, defined as the laminate stiffness ratio along and perpendicular to the main loading direction, has a major effect. Computational modelling was carried out using the finite element method to quantify the residual strength; in which ply fracture is modelled using the continuum damage mechanics approach.

• Periodical: Advanced Materials Research (Volumes 891-892)
• Pages: 178-184
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.891-892.178
• Online since: March 2014
• Authors: Mitesh Patel*, Stephen Daynes, Chun H. Wang
• Keywords: Composite, Continuum Damage Mechanism, Finite Element Analysis (FEA), Notch Size, Scarf Hole

References

[1] Wang, C.H. and A.J. Gunnion, On the design methodology of scarf repairs to composite laminates. Composites Science and Technology, 2008. 68(1): pp.35-46.

DOI: 10.1016/j.compscitech.2007.05.045

[2] FAA, FAA Federal Aviation Regulations (FARS) Part 23, in Section 573-Damage tolerance and fatigue evaluation of structure2005.

[3] Wang, C. and A. Gunnion, Optimum shapes of scarf repairs, 2009, Pergamon.

[4] Wang, C.H., et al., Residual strength of composite laminates containing scarfed and straight-sided holes. Compos. Pt. A-Appl. Sci. Manuf., 2011. 42(12): p.1951-(1961).

DOI: 10.1016/j.compositesa.2011.08.020

[5] Lee, J. and C. Soutis, A study on the compressive strength of thick carbon fibre–epoxy laminates. Composites Science and Technology, 2007. 67(10): p.2015-(2026).

DOI: 10.1016/j.compscitech.2006.12.001

[6] Sivashanker, S., N.A. Fleck, and M.P.F. Sutcliffe, Microbuckle propagation in a unidirectional carbon fibre-epoxy matrix composite. Acta Materialia, 1996. 44(7): pp.2581-2590.

DOI: 10.1016/1359-6454(95)00410-6

[7] Soutis, C. and J. Lee, Scaling effects in notched carbon fibre/epoxy composites loaded in compression. Journal of Materials Science, 2008. 43(20): pp.6593-6598.

DOI: 10.1007/s10853-008-2807-7

[8] Wisnom, M.R., S.R. Hallett, and C. Soutis, Scaling effects in notched composites. Journal of Composite Materials, 2010. 44(2): pp.195-210.

DOI: 10.1177/0021998309339865

[9] Cytec, VTM260 series, 2012, Cytec Industrial Materials (Derby) Ltd.

[10] MTT, NASA. 01142. 10 Short Block Compression Fixture, 2003, Material Testing Technology: USA.

[11] Dharmawan, F., C.H. Wang, and A. Rider, Computational analysis of the Influence Material Orthotropy on the Residual Strength of Laminated Composites, 2010, Perth, W.A.: Engineers Australia. pp.1422-1433.

[12] Shah, P.D., et al., Evaluation of Notched Strength of Composite Laminates for Structural Design. Journal of Composite Materials, 2010. 44(20): pp.2381-2392.

DOI: 10.1177/0021998310372713

[13] Hillerborg, A., M. Modéer, and P.E. Petersson, Analysis of crack formation and crack growth in concrete by means of fracture mechanics and finite elements. Cement and Concrete Research, 1976. 6(6): pp.773-781.

DOI: 10.1016/0008-8846(76)90007-7

[14] Wang, C.H., et al., Residual strength of composite laminates containing scarfed and straight-sided holes. Composites Part A, 2011. 42: p.1951-(1961).

DOI: 10.1016/j.compositesa.2011.08.020

[15] Chishti, M., et al., Characterising fibre compression fracture toughness of composites using bearing tests. Composites Part A, 2012. 43(10): pp.1775-1782.

DOI: 10.1016/j.compositesa.2012.05.005