Cutting behavior of flax fibers as reinforcement of biocomposite structures involving multiscale hygrometric shear

Abstract This paper aims to investigate the effect of water absorption on the cutting behavior of biocomposites using flax fiber reinforced polylactic-acid (PLA) and the orthogonal cutting process. Different immersion times have been considered from 1 to 150 days in order to investigate both transient and saturated hygrometric regimes. Machining forces are measured during the cutting process and the machined surfaces are analyzed using a scanning electron microscope and an optical interferometer. The in-situ removed chip morphologies are captured by a high-speed camera. Results show a functional relationship between the multiscale hygro-mechanical properties of flax fiber composites and their shear mechanisms that are controlled by the water content. The water uptake modifies the cellulosic structure of natural flax fibers in the transient regime and damages the fiber/matrix interfaces in the saturated regime, which affects considerably the cutting mechanisms and the machinability of the biocomposite structure at different scale levels.