Micromechanical Model for Predicting the Tensile Properties of Guadua angustifolia Fibers Polypropylene-Based Composites

In this paper, the one-dimensional tensile behavior of Guadua angustifolia Kunth fibre/polypropylene (PP+GAK_S) composites is modeled. The classical model of Kelly–Tyson and its Bowyer–Bader’s solution is not able to reproduce the entire stress–strain curve of the composite. An integral (In-Built) micromechanical model proposed by Isitman and Aykol, initially for synthetic fiber-reinforced composites, was applied to predict micromechanical parameters in short natural fiber composites. The proposed method integrates both the information of the experimental stress-strain curves and the morphology of the fiber bundles within the composite to estimate the interfacial shear strength (IFSS), fiber orientation efficiency factor ${\eta }_{\mathrm{FOD}}$, fiber length efficiency factor ${\eta }_{\mathrm{FLD}}$ and critical fiber length $l_c$. It was possible to reproduce the stress-strain curves of the PP+GAK_S composite with low residual standard deviation. A methodology was applied using X-ray microtomography and digital image processing techniques for the precise extraction of the micromechanical parameters involved in the model. The results showed good agreement with the experimental data.