A Novel Grain-Based DEM Model for Evaluating Surface Integrity in Scratching of RB-SiC Ceramics

Prior research has shown that scratching processes in ceramics involve complex interactions between tool geometry, material microstructure, and applied forces. However, the specific mechanisms of subsurface damage and material removal modes remain unclear. Established knowledge includes the role of grain boundaries and bonding in ceramic behavior under mechanical stress. No prior work had resolved how varying scratching parameters affect crack propagation and subsurface damage. This gap motivated the development of a grain-based model to simulate these interactions. The model aims to distinguish between transgranular and intergranular failure modes. It also seeks to clarify how scratching speed and depth influence damage depth. The study builds on prior computational methods used in ceramic machining simulations. It introduces a novel approach to represent SiC and Si grain interactions.

The aim is to develop a grain-based DEM model to simulate the scratching of RB-SiC ceramics and assess surface integrity. The specific problem involves understanding how scratching parameters influence crack formation and material removal. The motivation stems from the need to optimize machining processes for ceramic materials. The model must capture both ductile and brittle removal mechanisms. It should also evaluate the impact of scratching speed and depth on subsurface damage. The study seeks to identify how tool geometry affects surface integrity. It aims to provide insights into crack propagation patterns. The model is intended to guide improvements in machining strategies for RB-SiC ceramics.

The study uses a Discrete Element Method (DEM) model calibrated for RB-SiC ceramics. The model incorporates bonded SiC and Si grains along with cementitious materials. It simulates the scratching process by varying parameters like speed and depth. The model tracks crack initiation and propagation at the grain level. It distinguishes between transgranular and intergranular crack types. The simulation evaluates material removal modes as ductile or brittle. The model also considers the role of cutting-edge radius in damage reduction. It uses computational tools to analyze subsurface damage patterns.

The grain-based DEM model successfully identifies transgranular and intergranular cracks. It distinguishes between ductile and brittle material removal mechanisms. Increasing scratching speed reduces subsurface damage depth. Decreasing depth of cut also lowers subsurface damage. Low scratching speed or high depth of cut increases transgranular cracking. This leads to large grain spalling and median crack propagation. Increasing cutting-edge radius enhances ductile machinability. It reduces subsurface damage in the target material.

The DEM model accurately captures crack types and material removal modes in RB-SiC ceramics. It shows that scratching speed and depth significantly influence subsurface damage. Low speed or high depth increases transgranular cracking and spalling. Cutting-edge radius affects surface integrity and ductile behavior. The model provides insights into optimizing machining parameters. It supports improved strategies for ceramic surface finishing. The findings align with the authors' goal of evaluating surface integrity. The study contributes to understanding ceramic machining mechanisms.