Discrete element modeling of the machining processes of brittle materials: recent development and future prospective

Abstract

In recent years, the discrete element method (DEM) has been used to model the bulk material, especially for the brittle materials (such as rocks, ceramics, concrete, ice, etc.) with various mechanical properties or responses by setting serials of contact properties (such as bonds) in the particle assembly. These bonds can withstand a certain amount of force and/or moment, so that the stresses executed in the bond can be used for determining the initiation and propagation of micro-crack. There are increasing evidences over the last twenty years that the DEM is becoming an effective numerical method to simulate the cracking, crushing and deformation of continuous media under external loads. The DEM has now been widely used in the field of processing and machining of rock, ceramic, concrete and other brittle materials. In this paper, the theoretical principles, formulations, contact models as well as the numerical solving processes of DEM are introduced. The applications of DEM for the machining processes of brittle and rigid materials such as ceramics are described and reviewed in detail, with future development trend also discussed.

Experimentally Induced Thermal Fatigue on Lunar and Eucrite Meteorites—Influence of the Mineralogy on Rock Breakdown

“…This includes initial sawing of rocks followed by gradually finer polishing to remove the damaged layers and end up with a smooth and intact surface. The general procedure and the forces acting on the sample are tremendously different from those being applied during for example, grinding rocks in mining processes (e.g., Liu et al., 2019), as well as sawing and polishing (e.g., Jiang et al., 2020). There are additional arguments supporting the thermal stress induced micro‐flaking: First, we note that the force applied on the samples during, for example, sawing and polishing is less than during bedrock fragmentation by impact cratering, that is, the primary mechanism of formation of lunar rocks.…”

Research on the Grinding Energy Density in a Jet Mill

“…Regular crystals are difficult to observe in the internal structure of solid materials. Microscopic observations show the presence of aggregates with an incorrectly distorted spatial form and randomly distributed clusters of crystals, called crystallites [57,58]. In addition, defects in the internal crystal lattice structure, along with micropores, microcracks, the inclusions of other defects or other minerals, often constitute the natural structure of these materials.…”