Investigation on the effects of microstructure on machining unidirectional carbon fiber reinforced polymer composites with a modified force model

The paper aims to investigate the correlation of microstructural characteristics and machinability of unidirectional carbon fiber reinforced polymer composites by a modified analytical model. A representative volume element was selected to present the microstructure and analyze the force distribution, in which the interphase between the fiber and the matrix was considered significantly. And the microstructure can be obviously measured by using microscopic observation, especially the interphase was found to be around 0.3 μm in the used carbon fiber reinforced polymer composites. To study the representative volume element effect on the cutting behavior of unidirectional carbon fiber reinforced polymer composites, the prediction of cutting force was done by using a modified force model. Compared with the experiments, the developed model can well predict the cutting forces and subsurface damage in the carbon fiber reinforced polymer composites cutting. It was found that surface integrity as well as subsurface damage has a coincident varying trend with the fiber orientations, as confirmed by the observations of the machined surface at different fiber orientations. The good surface integrity can be obtained at the low fiber orientation of 0° and the poor surface occurs at the large fiber orientation of 135°. Moreover, the effect of interphase and the fiber volume fraction in representative volume element were further investigated. The results show that the cutting forces increase with increasing the fiber volume fraction as well as the interphase volume fraction, and the interphase affects the cutting force in the transverse direction is significantly higher than that in longitudinal direction.