Theoretical analysis of mechanical properties in natural fibres under quasi-static load: a case study of Ichu and Cabuya

Natural fibres are gradually replacing glass fibres in textile products or wind turbines blades. Stipa Obtusa (Ichu) and Furcraea (Cabuya) are two endemic plants that abound in the highland Andean areas and they could be used as reinforcements; however, there is missing information about their anisotropic behaviour. This study aims to predict the elastic constants of these two fibres based on the results of unidirectional tensile tests using an elasticity-based model. The latter was employed to calculate the average S2 layer microfibril angle for Ichu and Cabuya: 23.10 degrees and 18.98 degrees, respectively; and predict the longitudinal elastic constant, using four different finite-element arrangements, with mean errors of 11% and 5.5% for Ichu and Cabuya, respectively. Besides, the inclusion of geometrical and chemical variables such as the crystallinity index and the MFA in the model helped predict the stiffness matrices of Ichu and Cabuya. This could help researchers in modelling bio-sourced composites RVE's employing simplified models.