Discrete/Finite Element Modelling of Industrial Applications with Multi-fracturing and Particulate Phenomena

摘要

The classical discrete element method (DEM) proposed by Cundall and Strack (1979) has been proved to be a versatile numerical tool, particularly suitable for the simulation of granular and particulate systems typically encountered in process engineering and geomechanics. Such systems are of an inherent discrete nature and often consist of an excessively large number of individual particles. The overall behaviour of the systems is determined by the motion of these individual particles involving interaction mainly through adhesive/frictional contact. In principle, the DEM is based on the concept that individual material elements, each usually assumed to be rigid, are considered to be separate and are (possibly) connected only along their boundaries by appropriate physically based interaction laws. Many other industrial and scientific problems are, on the other hand, characterised by a transformation from a continuum to a discontinuum state. For example, material separation and progressive failure phenomena can be found in applications such as concrete structural failure, food technology processes, rock blasting operations and fracture of ceramic or other quasi-brittle materials under high velocity impact. The problems are initially represented by a small number of discrete regions (often a single entity) prior to the deformation process. During the loading phase, the bodies are progressively damaged and modelling of the subsequent fragmentation may result in possibly three to four orders of magnitude more bodies by the end of the simulation. The overall system response is governed firstly by appropriate constitutive mechanisms which control the material separation process followed by description of the inter-element interaction forces which can be short-ranged, such as mechanical contact, and/or medium-ranged, such as attraction forces in liquid bridges, which control the subsequent motion of particles.