487 MODELING A COMPOSITE REINFORCED WITH SHORT ALFA FIBERS TO DETERMINE ITS FATIGUE AND STRUCTURAL HOMOGENIZATION A. Nour, 1* H. Mechakra, 1 B. Benkoussas, 1 I. Tawfq, 2 A. T. Settet, 1 and R. Renane 3 Keywords: Mori–Tanaka model, Eshelby tensor, Alfa fbers. The fatigue and homogenization of polypropylene reinforced with untreated and chemically treated short Alfa fbers were investigated using a modifed Mori–Tanaka model. The polypropylene with chemically treated fbers showed a higher resistance than that with untreated ones. Cylindrical fbers with elliptical cross sections were used in experiments. Their mechanical characteristics were determined by the inverse method. 1. Introduction The fatigue behavior of vegetal-fber composites has been investigated rarely, and even less attention has been given to composite materials reinforced with Alfa fbers. Towo and Ansell [1, 2] studied the fatigue of sisal/epoxy and sisal/polyester composites. The S–N curves were presented for reinforced composites with untreated sisal fbers and sisal fbers treated with 0.06 NaOH. The sisal/epoxy composites showed a longer fatigue life than the sisal/polyester ones. In addition, the effect of the chemical treatment on the fatigue life was more signifcant for the sisal/polyester reinforced composites. Silva et al. [3] identifed the tensile fatigue behavior of cement composites reinforced with long aligned sisal fbers. The fatigue behavior was examined in terms of stress versus the number of cycles and the stress–strain hysteresis of the composites. Elouaer et al. [4] studied the fatigue response of different varieties of composites with an injected hemp reinforcement. The authors found that the fatigue strength of hemp/PP was higher than that of hemp/CP. Similarly, Reis et al. [5] studied the fexural behavior of manually manufactured hybrid laminated composites with a natural hemp fber/ Mechanics of Composite Materials, Vol. 54, No. 4, September, 2018 (Russian Original Vol. 54, No. 4, July-August, 2018) 1Dynamics of Engines and Vibroacoustic Laboratory, F.S.I., M.B. Boumerdes University, Algeria 2Laboratoire QUARTZ(EA7393), Supmeca, 3 rue de Fernand Hainaut, 93407 Saint-Ouen Cedex, France 3Université Saad Dahlab, département d’Aéronautique, Blida, Algérie * Corresponding author; tel./fax: +213 24913099; e-mail: abdelkader_nour@hotmail.fr 0191-5665/18/5404-0487 © 2018 Springer Science+Business Media, LLC Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 54, No. 4, pp. 709-724, July-August, 2018. Original article submitted September 14, 2017. DOI 10.1007/s11029-018-9758-0