Effect of hygrothermal conditioning on the machining behavior of biocomposites

Abstract

This work aims to study the cutting behavior of biocomposites under different controlled hygrothermal conditions. This investigation choice is motivated by the fact that natural plant fibers such as flax are characterized by their hydrophilicity which makes them able to absorb water from a humid environment. This absorption ability is intensified when increasing the conditioning temperature. The moisture diffusion process affects considerably the mechanical properties of the resulting composite, which causes many issues during the machining operations. In this paper, moisture diffusion, chip form, cutting and thrust forces, and the microscopic state of the machined surfaces are considered to explore the cutting behavior of biocomposites in the function of the hygrothermal conditioning time. Results reveal that moisture content in the biocomposite is significantly influenced by the conditioning temperature and the fiber orientation. The evolution of the moisture content and the increase of the fiber orientation affect both the chip morphology in terms of curling as well as the tool/chip interaction in terms of friction. The cutting behavior of flax fibers depending on hygrothermal conditioning time is then investigated using microscopic observations of the machined surfaces in addition to analytical modeling. An analysis of variance is used finally to quantify the observed results.