Prediction of the mechanical behavior of flax polypropylene composites based on multi-scale finite element analysis

Natural fibers and their composites differ in several aspects with carbon fibers, including higher scatter in strength and different tensile responses. The tensile and bending properties of flax fiber composites were experimentally studied and numerically simulated. Composite panels were fabricated from unidirectional flax fiber tapes and polypropylene films via hot pressing technique. The variation in the properties of flax/polypropylene composites was found to be relatively moderate as compared with that of single natural fibers. A multi-scale finite element analysis (FEA) strategy for the progressive damage prediction of natural fiber composites was developed. The FEA model started from micro-scale analysis which predicted the effective properties of unidirectional flax ply through representative volume element. Macro-scale analysis was conducted subsequently to predict the properties of composite coupons using the results of micro-scale analysis as inputs. The developed multi-scale FE model successfully predicted the tensile strength, bending behavior, and major failure modes of flax/polypropylene composites.