TY - THES

T1 - A DEM Model for Complex-Shaped Particles to Simulate Breakage in Large-Scale Simulations

AU - Platzer, Felix

N1 - no embargo

PY - 2022

Y1 - 2022

N2 - In Discrete Element Method (DEM) simulations, the breakage behavior of particles can be simulated based on different principles. In the case of large, complex-shaped particles that show various breakage patterns depending on the scenario leading to the failure and often only break locally instead of fracturing completely, some of these principles do not lead to realistic results. The reason for this is that in said cases, the methods in question, such as the Particle Replacement Method (PRM) or Voronoi Fracture, replace the initial particle (that is intended to break), also called the parent-particle, into several sub-particles when certain breakage criteria are reached, such as exceeding the fracture energy. That is why those methods are commonly used for the simulation of materials that fracture completely instead of breaking locally.When simulating local particle failure, it is advisable to pre-build the initial particle from sub-particles that are bonded together. The dimensions of these sub-particles consequently define the minimum size of the fracture results. This structure of bonded sub-particles enables the initial particle to break at the locations of the highest local loads – due to the failure of the bonds in those areas – with several sub-particle clusters being the result of the fracture, which can again also break locally.In this thesis, different methods for the generation and calibration of complex-shaped particle conglomerates using bonded-particle modeling (BPM) to enable the ability to depict more realistic fracture behavior are evaluated based on the example of rock-like materials, in this context specifically filter cake. The detailed method that proved suitable for this purpose and which furthermore allows efficient and realistic simulation of breakage behavior of complex-shaped particles is presented in this thesis.In order to simulate industrial-sized processes with several differently shaped parent-particles, following major aspects, among others, are taken into account. A correlating mass and volume flow during the breakage process is maintained, enabled by a approach using large overlaps in combination with a relaxation model after breakage of the bondings. Dynamic behavior of the parent-particles especially regarding bonding-structure-wide damping is considered. Also, the detection of different sub-particle clusters resulting from the breakage of bonded-particle structures is of major interest and is thus covered respectively. Optimization in regard to computational efficiency is further achieved by introducing the "bonded-particle replacement method" (BPRM), combining the advantages of the BPM with those of the PRM.By developing virtual prototypes instead of physical ones, and furthermore reducing the required efforts in context with these virtual prototypes and their successful simulation, the required resources are reduced and a step towards sustainability is taken.

AB - In Discrete Element Method (DEM) simulations, the breakage behavior of particles can be simulated based on different principles. In the case of large, complex-shaped particles that show various breakage patterns depending on the scenario leading to the failure and often only break locally instead of fracturing completely, some of these principles do not lead to realistic results. The reason for this is that in said cases, the methods in question, such as the Particle Replacement Method (PRM) or Voronoi Fracture, replace the initial particle (that is intended to break), also called the parent-particle, into several sub-particles when certain breakage criteria are reached, such as exceeding the fracture energy. That is why those methods are commonly used for the simulation of materials that fracture completely instead of breaking locally.When simulating local particle failure, it is advisable to pre-build the initial particle from sub-particles that are bonded together. The dimensions of these sub-particles consequently define the minimum size of the fracture results. This structure of bonded sub-particles enables the initial particle to break at the locations of the highest local loads – due to the failure of the bonds in those areas – with several sub-particle clusters being the result of the fracture, which can again also break locally.In this thesis, different methods for the generation and calibration of complex-shaped particle conglomerates using bonded-particle modeling (BPM) to enable the ability to depict more realistic fracture behavior are evaluated based on the example of rock-like materials, in this context specifically filter cake. The detailed method that proved suitable for this purpose and which furthermore allows efficient and realistic simulation of breakage behavior of complex-shaped particles is presented in this thesis.In order to simulate industrial-sized processes with several differently shaped parent-particles, following major aspects, among others, are taken into account. A correlating mass and volume flow during the breakage process is maintained, enabled by a approach using large overlaps in combination with a relaxation model after breakage of the bondings. Dynamic behavior of the parent-particles especially regarding bonding-structure-wide damping is considered. Also, the detection of different sub-particle clusters resulting from the breakage of bonded-particle structures is of major interest and is thus covered respectively. Optimization in regard to computational efficiency is further achieved by introducing the "bonded-particle replacement method" (BPRM), combining the advantages of the BPM with those of the PRM.By developing virtual prototypes instead of physical ones, and furthermore reducing the required efforts in context with these virtual prototypes and their successful simulation, the required resources are reduced and a step towards sustainability is taken.

KW - onded particle model (BPM)

KW - DEM

KW - filter cake

KW - Particle breakage

KW - Particle fracture

KW - bonded-particle replacement method (BPRM)

KW - onded particle model (BPM)

KW - DEM

KW - filter cake

KW - Particle breakage

KW - Particle fracture

KW - bonded-particle replacement method (BPRM)

U2 - 10.34901/mul.pub.2022.06

DO - 10.34901/mul.pub.2022.06

M3 - Master's Thesis

ER -