Abstract: In this paper, flax fiber reinforced polylactic acid composites (FFRP) and flax/basalt hybrid fiber reinforced polylactic acid composites (FBFRP) were made. The tensile and bending tests were carried out to analyze the effects of fiber content and hybrid fiber on the mechanical properties of the composites. Combined with differential scanning calorimetry (DSC) test, the mechanical properties of the composites were analyzed. The results show that for FFRP, when the content of flax fiber exceeds 20%, the tensile properties of the composites increase with the increase of fiber content, and reach the highest value at 40%. A small amount of flax fiber may cause internal defects of the material, and too much fiber content will form agglomeration, which will lead to a decline in the performance of the composite material. For FBFRP, the mechanical properties of the composites are enhanced by adding appropriate content of basalt fiber. When the content of flax and basalt fiber is 30% and 9% respectively, the mechanical properties of the material are the best. Finally, based on the Halpin-Tsai empirical formula and the transversely isotropic numerical simulation including the Tsai-Wu failure criterion, a prediction method for the mechanical properties of hybrid composites is established to accurately evaluate and predict the mechanical properties of hybrid fiber reinforced composites with different fiber contents.

Key words: flax fiber, basalt fiber, hybrid composites, DSC test, prediction of mechanical properties