A Fracture Mechanics Approach to Modeling Strength Degradation in Ceramic Grinding Processes

Abstract

Strength degradation of the finished part due to surface and sub-surface damage is a critical issue in grinding of ceramic materials. In this paper, the chip formation process is modeled as a two-dimensional system of radial and lateral cracks, and an integral equation approach is developed to investigate the interactions of these radial and lateral cracks with various distributions of planar microcracks. The effects in the vicinity of the free surface are modeled explicitly. The amplification and shielding effects on stress intensity factors due to various microcrack distributions are studied in detail. Numerical results are presented for crack systems representing single-grit as well as multi-grit grinding, and the implications of crack interactions on strength degradation of finished products are discussed. Effective elastic properties for workpieces containing microcrack distributions are obtained and their ramifications on the grinding process are investigated. Some benevolent microcrack distributions that will facilitate chip formation as well as suppress surface and subsurface damage evolution are also presented.