Advanced structural analysis methods that account for manufacturing defects in composite parts are needed to enable accurate assessment of their capability and useful life and to enhance current design and maintenance practices. In particular, porosity/voids are typical defects in carbon/epoxy and glass/epoxy composite aircraft flight-critical components. High-fidelity nondestructive evaluation by X-ray computed tomography allows accurate defect measurement and automatic conversion to structural models to assess the effects of defects on structural properties. This study presents a comprehensive structural analysis methodology, which includes nondestructive detection and finite element modeling of the defects in composites. Effects of porosity/voids on interlaminar tensile and shear strength of unidirectional carbon/epoxy composite specimens are investigated. Failure predictions and subsequent test correlations are presented.
Makeev A, Nikishkov Y, Carpentier P, et al. Manufacturing issues and measurement techniques for assessment of the effects on structural performance of composite parts. In: Proceedings of the 66th American helicopter society international annual forum, Phoenix, Arizona, 11–13 May 2010.
2.
Makeev A and Nikishkov Y. Fatigue life assessment for composite structure. In: (ed J Komorowski) ICAF 2011 Structural integrity: influence of efficiency and green imperatives, Berlin, Germany: Springer-Verlag, 2011; pp. 119–134.
3.
OlivierPCottuJPFerretB. Effects of cure cycle pressure and voids on some mechanical properties of carbon/epoxy laminates. Composites1995; 26: 509–515.
4.
CostaMLAlmeidaSFM. The influence of porosity on the interlaminar strength of carbon/epoxy and carbon/bismaleimide fabric laminates. Compos Sci Technol2001; 61: 2101–2108.
5.
WisnomMRReynoldsTGwilliamN. Reduction in interlaminar shear strength by discrete and distributed voids. Compos Sci Technol1996; 56: 93–101.
6.
VarnaJJoffeRBerglundLALundströmTS. Effect of voids on failure mechanisms in RTM laminates. Compos Sci Technol1995; 53: 241–249.
7.
HagstrandPOBonjourFMansonJAE. The influence of void content on the structural flexural performance of unidirectional glass fibre reinforced polypropylene composites. Compos Part A2005; 36: 705–714.
8.
AlmeidaSFMNetoZSN. Effect of void content on the strength of composite laminates. Compos Struct1994; 28: 139–142.
9.
MadsenBLilholtH. Physical and mechanical properties of unidirectional plant fibre composites—an evaluation of the influence of porosity. Compos Sci Technol2003; 63: 1265–1272.
10.
HuangHTalrejaR. Effect of void geometry on elastic properties of unidirectional fiber reinforced composites. Compos Sci Technol2005; 65: 1964–1981.
11.
RicottaMQuaresiminMTalrejaR. Mode I Strain Energy Release Rate in composite laminates in the presence of voids. Compos Sci Technol2008; 68: 2616–2623.
12.
LopesCSRemmersJJCGurdalZ. Influence of Porosity on the Interlaminar Shear Strength of Fibre-Metal Laminates. Key Engng Mater2008; 383: 35–52.
13.
ZhuHWuBLiDZhangandDChenY. Influence of voids on the tensile performance of carbon/epoxy fabric laminates. J Mater Sci Technol2011; 27: 69–73.
14.
LambertJChambersARSinclairISpearingSM. 3D damage characterisation and the role of voids in the fatigue of wind turbine blade materials. Compos Sci Technol2012; 72: 337–343.
Makeev A, Nikishkov Y, Seon G, et al. Fatigue structural substantiation for thick composites. In: Proceedings of the 17th international conference on composite materials, Edinburgh, UK, 27–31 July 2009.
17.
ASTM Standard D6415/D6415M. Standard test method for measuring the curved beam strength of a fiber-reinforced polymer-matrix composite. West Conshohocken, PA, USA: ASTM International, 2006.
18.
MakeevAHeYCarpentierPShonkwilerB. A method for measurement of multiple constitutive properties for composite materials. Compos Part A2012; 43: 2199–2210.
19.
HeYMakeevAShonkwilerB. Characterization of nonlinear shear properties for composite materials using digital image correlation and finite element analysis. Compos Sci Technol2012; 73: 64–71.
20.
MakeevASeonGLeeE. Failure predictions for carbon/epoxy tape laminates with wavy plies. J Compos Mater2010; 44: 95–112.
21.
CamanhoPPLambertM. Design methodology for mechanically fastened joints in laminated composite materials. Compos Sci Technol2006; 66: 3004–3020.
