Mechanical model and removal mechanism of unidirectional carbon fibre-reinforced ceramic composites. (1st May 2020) - Qu, Shuoshuo
Highlights: Through an analysis of the supporting and boundary conditions of a fibre, a new mechanical model was proposed. In the development of the mechanical model, the formation area of the grinding chips, the friction zone of the abrasive grain and the number of active abrasives were analysed in detail and subsequently discussed. The new model offers a cross-scale and cross-level method to analyse the grinding process from the fibre deflection to the formation of macroscale grinding debris. Based on the topographies of the grinding chips and surfaces, the failure processes of the fibre and matrix due to the forward motion of the abrasive grains were analysed. Abstract: Numerous scholars have researched the influences of grinding parameters on the surface quality and grinding forces of carbon fibre-reinforced silicon carbide ceramic matrix (Cf /SiC) composites. Nevertheless, the relevant mechanical model and removal mechanism have not been investigated from a microscale perspective. To develop a mechanical model, the area of formation of the grinding chips should be analysed in detail and discussed. The supporting conditions and debonding depth are critical to the grinding forces. To validate the reliability of the mechanical model, experiments with the same grinding parameters were performed. The differences between the theoretical and experimental results were small, which indicated that the mechanical model was accurate and reasonable. Based on the theoretical analyses and experimental results, the material removal mechanism was explored in detail. Based on the topographies of the grinding chips and surfaces, the failure processes of the fibre and matrix due to the forward motion of the abrasive grains were analysed. As the grinding depth increased, the evaluation indexes of the debonding depth, grinding forces and grinding chips gradually increased. Moreover, the increasing proportions of fibre pullout and fibre outcrop indicated that the quality of the grinding surface decreased. Based on the research findings, the debonding depths, grinding forces, grinding chips and surface topographies of unidirectional Cf /SiC composites can be determined, which is expected to significantly improve the machining ability of Cf /SiC composites. Graphical abstract: Image, graphical abstract