PSI - Issue 8

A. Pantano et al. / Procedia Structural Integrity 8 (2018) 517–525 A. Pantano, B. Zuccarello / Structural Integrity Procedia 00 (2017) 000–000

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fiber biocomposites is related to the volume fraction of fibers by a linear law. Numerical simulations have also shown that, fixed the volume fraction, the longitudinal Young’s module is linked to the ratio of a/l by an exponential law (the effects grow exponentially as a/l grows). In particular, the effects are almost negligible, i.e. less than about 2%, for a/l <0.05, while they become significant, greater than 10%, for a/l > 0.125. The experimental results were performed by manufacturing unidirectional biocomposite laminates with perfectly aligned fibers, obtained using unidirectional fabrics specially made in the laboratory after stitching and stretching of fibers, and biocomposite laminates made of two layers with fibers arranged in a sinusoidal shape in opposition of phase and with a/l = 0.05 and V f = 0.2. From such laminates, packaged by manual lamination and vacuum bag, rectangular specimens have been obtained to be used for traction tests. The tests performed fully confirmed the numerical results, showing that the effects of waviness on the longitudinal modulus of the biocomposite with a/l = 0.05 were on average not more than 2%. Much more significant are the effects on the resistance which decreased by about 14%. The experimental analysis also allowed us to detect how fiber waviness can give rise to more significant effects located in the areas of the biocomposite where the fibers form the maximum misalignment angle with the direction of application of the load. For example, considering the mid-section of the wavy fiber specimens tested, stiffness decreases in excess of 12% and resistance decreases of about 14%. Further developments of this work relate to the development of numerical models capable of assessing local effects on the stiffness as well as the effects on the strength of biocomposites under stress. Bednarcyk, B.A., Aboudi, J., Arnold, S.M., 2014. 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