Effect of the raster orientation on strength of the continuous fiber reinforced PVDF/PLA composites, fabricated by hand-layup and fused deposition modeling

Abstract

This paper presents the fabrication of a new class of high-porous composites made of polylactic acid (PLA) matrix reinforced with polyvinylidenfluorid (PVDF) long fibers. The composites were produced by printing the PLA matrix by using Fused Deposition Modeling (FDM) and adding continuous PVDF fibers by hand-layup. Materials properties were investigated, including the influence of two raster orientations during 3D printing ([0, 90] and [−45, +45]), by tensile and three-point bending tests. Experiments revealed that PVDF fibers within PLA matrices modified the composites behaviour providing higher ductility, whilst flexural strength decreased. Observation of the fracture surfaces showed that cracks followed the raster orientation lines avoiding a complete failure of the material structures and fibers (whereas unreinforced pure PLA samples fully broke). Composite configuration with [−45, +45] raster orientation exhibited higher strength and stiffness in comparison to the [0, 90] orientation, both in tensile and flexural conditions. Tensile failure was dominant in [−45, +45], and less influential in [0, 90]. Numerical models were also developed and compared. Two alternative approaches were considered in material modeling: Mori – Tanaka and ‘two-material’ models. No relevant differences emerged and a good agreement with experiments was achieved.