The present work aims at developing an analytical model of shear-lag of a cell of unidirectional composites made from natural fibers (Alfa) with irregular spacing between fibers. The finite difference method is used to calculate the "Stress Concentration Factor" (SCF) at the neighboring fibers. By the development of a pattern of three-dimensional finite differences with random spacing between fibers, a coupled system of equations is obtained for the displacement and stress concentration in the fibers. By varying the distance between the fibers and their diameters, the sensitivity distribution of the SCF is evaluated along the fibers. A probabilistic analysis of a cell of a unidirectional composite having a break in the central fiber is then conducted to evaluate the effect of geometrical and mechanical uncertainties on the evolution of the stress concentration. The probabilistic study is performed using Monte Carlo simulations to assess the sensitivity of the model with respect to geometrical and mechanical uncertainties.
unidirectional composite, natural fiber, broken fiber transfer, finite difference, stress concentration.
Amirat A., Chateauneuf A. M., Chaoui K. (2006). Reliability assessment of underground pipelines under the combined effect of active corrosion and residual stress. International Journal of Pressure Vessels and Piping 83, 107–117.
Ang A.H.-S., TangW.H. (1984). Probability Concepts in Engineering Planning and Design. Vol.1 & 2. John Wiley and Sons.
Atadero R., Luke Lee L., Karbhari V.M. (2005). Consideration of material variability in reliability analysis of FRP strengthened bridge decks. Composite Structures 70, 430–443.
Bandorawalla T. J. (2002). Micromechanics-based strength and lifetime prediction of polymer composites. Doctor of Philosophy in Engineering Mechanics, Blacksburg, Virginia, USA.
Béakou A, Mohamed A. (2001). Influence of variable scattering on the optimum winding angle of cylindrical laminated composites. Composite Structures, 53 287–293.
Bouhafs M., Sereir Z., Chateauneuf A. (2012). Probabilistic analysis of the mechanical response of thick composite pipes under internal pressure. International Journal of Pressure Vessels and Piping 95, 7-15.
Bouhamida B., Sereir Z., Chateauneuf A. (2013). Uncertainties of stress intensification near broken fibers of unidirectional composite with random fiber spacing. Theoretical and Applied Fracture Mechanics 65, 1–7.
Carrere N., Rollet Y., Leroy F. H., Maire J.F. (2009). Efficient structural computations with parameters uncertainty for composite applications. Composites Science and Technology 69, 1328–1333.
Khiat M.A., Sereir Z., Chateauneuf A. (2011). Uncertainties of unidirectional composite strength under tensile loading and variation of environmental condition. Theoretical and Applied Fracture Mechanics 56, 169–179.
Lemaire M., Chateauneuf A., Mitteau J. C. (2005). Fiabilité des structures : couplage mécano-fiabiliste statique. Ed. Hermès-Lavoisier, Paris.
Motley M.R, Young Y.L. (2011). Influence of uncertainties on the response and reliability of self-adaptive composite rotors. Composite Structures 94, 114–120.
Rouhi M., Rais-Rohani M. (2013). Modeling and probabilistic design optimization of a nanofiber-enhanced composite cylinder for buckling. Composite Structures, 95, 346-353