This paper was produced for the 2019 NAFEMS World Congress in Quebec Canada
In the field of material handling and conveying technology, the "Discrete Element Method" (DEM) is used to simulate the movements of bulk materials in conveyor systems with numerical calculation software. In such DEM-simulations of various belt conveyor systems, the belts themselves are usually modelled as rigid bodies, whereby the belt behaviour and the resulting effects are not taken into account. Some of these behaviours and effects are occurring stresses, deformations or belt movements. Also, dynamic interactions between a belt and conveyed bulk as well as interactions between a belt and other system components, for example idlers, cannot be depicted digitally with those rigid belt models.
Therefore, a methodology has been developed at the University of Leoben that enables the consideration of dynamic belt behaviour in DEM-simulations of belt conveyors during bulk conveying processes. In cooperation with a software development company the essential features to set up such simulations were implemented in a commercial DEM-software.
The basic approach to model the conveyor belt is to build up the belt by systematically arranging discrete particles and connecting them together to a particle mesh with so called bondings. Belt properties can be defined on the one hand via the particle parameters and on the other hand via the bonding parameters. These parameters must be tuned so that the virtual belt model behaves like a particular belt in reality. And as conveyor belts consist of multiple materials, like different layers, textile plies or steel cords and filling material, the developed bonding model also allows the digitally modelled belt to represent inhomogeneous material.
To ensure an efficient simulation with a dynamic belt model as described, an additional preprocessing method to generate the conveyor belt in the DEM-environment has been developed. According to this method, the belt is initialised in “almost-final state”, a condition that is close to the fully assembled final state of the belt in a particular conveyor system. By starting a simulation from this almost-final state, the pre-simulation effort to form the belt in its final assembled position is reduced to a minimum. For even more efficiency, the belt can also be generated in motion state so that an already running conveyor gets initialised.
The use of the developed methodology for the simulation of conveyor belts is particularly suitable for the simulation of belt conveyor systems with strong belt deformations and for systems in which the belt deformation or the belt behaviour in general have significant influence on the systems’ functionality. These are, for example, curved belt conveyors, pipe or sandwich conveyors and similar unconventional belt conveyor systems. Furthermore, this methodology is also eligible for the DEM-simulation of components of other application areas, as simulations of bulk bags (FIBCs) or wire ropes have shown.
Simulation tests of the methodology on exemplary belt conveyors provided results showing effects as they are expected in reality: occurrence of belt sag, corresponding conveying cross-sections, troughed shaping of the belt, etc. Especially the generation of the belt in the almost-final state provides a considerable contribution to the performance of the methodology in total. The relatively low computational effort required for simulations, showed that the developed methods are very efficient in their performance and thus promising in practical application for the simulation and analysis of entire belt conveyor systems.
|Date||18th June 2019|