Dem analysis of effect of the particle size during the material flow in wedge-shaped hopper

"The current analysis was mainly focused to the study of the strained physical effects arising from a decrease of the particles number. The main aspects concerning programming concepts as well as languages having influence on the computer time of simulations is also presented. The limitation in the particles amount was adopted by increasing the particle radii to keep constant the total mass of granular material. In this way, the performed computer simulations of the filling and discharge in three-dimensional hopper using 1980, 10000 and 20400 number of particles were shown that the decrease in particles number with increasing the particle radii produces an artificial friction due to material homogeneity. This is results in the decreased mass fraction and its rate during discharge causing the longest time for the full material discharge; the decreased normal and increased shear pressure of walls

Dem analysis of effect of the particle size during the material flow in wedge-shaped hopper

"The current analysis was mainly focused to the study of the strained physical effects arising from a decrease of the particles number. The main aspects concerning programming concepts as well as languages having influence on the computer time of simulations is also presented. The limitation in the particles amount was adopted by increasing the particle radii to keep constant the total mass of granular material. In this way, the performed computer simulations of the filling and discharge in three-dimensional hopper using 1980, 10000 and 20400 number of particles were shown that the decrease in particles number with increasing the particle radii produces an artificial friction due to material homogeneity. This is results in the decreased mass fraction and its rate during discharge causing the longest time for the full material discharge; the decreased normal and increased shear pressure of walls

The transient behavior of rails used in electromagnetic railguns: numerical investigations at constant loading velocities

Electromagnetic railguns are mechatronic systems working at very high power levels (in the range of GW). Here, one important issue, namely, the dynamical reaction of the rails and their supporting structure to the moving (due to the projectile) magnetic pressure loads is still not sufficiently described. In this paper the above described problem is investigated using a purely mechanical 2D finite element model. The aim is to describe the displacement of the rail surfaces because of its importance for the electrical performance of the system. The boundary conditions correspond to the moving electromagnetic pressure repelling the rails one from each other. The oscillation profiles under several loading histories with constant velocities ranging between 0.6 and 1.4 km/s are examine

Interaction of particles via solid interface: model and analysis

The paper addresses discrete element (DEM) models of the heterogeneous particulate solids where the normal interaction between two deformable spherical particles bonded via weaker solid interface is considered. The integral interaction model aimed for evaluation of the bond stiffness was developed, where analytical expressions of the stiffness parameters reflecting individual contribution of the two particles and of the interface properties are derived. Application of the developed DEM model to particulate solid with many particles is considered. The accuracy and the suitability of this approach are evaluated by considering refined 3D Finite Element analysis

Simulation of sticking of adhesive particles under normal impact

Sticking of adhesive spherical particles under normal impact is investigated numerically by applying the Discrete Element Method. The nonlinear-dissipative contact model with adhesion is applied to model normal contact forces. Loading is described by elastic Hertz and elastic-plastic contact model with history-dependent adhesion. Damping is described by nonlinear Tsuji model. Adhesion limit is of linear character while particle detachment is of non-linear nature. Sticking and detachment behaviour for various damping values are considered in detail. Influence of the adhesion force for a wide range of particle sizes is illustrated by the variation of critical sticking velocity. Comparison of purely elastic with elastic-plastic behaviour is also presente

The transient behavior of rails used in electromagnetic railguns: numerical investigations at constant loading velocities

Electromagnetic railguns are mechatronic systems working at very high power levels (in the range of GW). Here, one important issue, namely, the dynamical reaction of the rails and their supporting structure to the moving (due to the projectile) magnetic pressure loads is still not sufficiently described. In this paper the above described problem is investigated using a purely mechanical 2D finite element model. The aim is to describe the displacement of the rail surfaces because of its importance for the electrical performance of the system. The boundary conditions correspond to the moving electromagnetic pressure repelling the rails one from each other. The oscillation profiles under several loading histories with constant velocities ranging between 0.6 and 1.4 km/s are examine

Failure analysis of destructive coils

The failure of the destructive pulsed power coils has been investigated. The destructive coil is the key element of the laboratory system which generates half-period abrupt magnetic field pulses with the amplitudes up to 45 T. The transient coupled non-linear magneto-mechanical model has been applied for finite element simulations. The mechanical behavior and operation threshold of the coil have been examined. It has been found that operation threshold of the coil with relatively thin cylindrical reinforcement could be characterized by the opening of the plastic hinge and estimated numerically. Good agreement with experimental results has been observe

Failure analysis of destructive coils

The failure of the destructive pulsed power coils has been investigated. The destructive coil is the key element of the laboratory system which generates half-period abrupt magnetic field pulses with the amplitudes up to 45 T. The transient coupled non-linear magneto-mechanical model has been applied for finite element simulations. The mechanical behavior and operation threshold of the coil have been examined. It has been found that operation threshold of the coil with relatively thin cylindrical reinforcement could be characterized by the opening of the plastic hinge and estimated numerically. Good agreement with experimental results has been observe

Analysis of fluid flow and heat transfer in district heating pipelines using the finite element method

The finite element method is applied to solve coupled steady-state fluid flow and heat transfer problems in insulated pipes of district heating networks. The main advantage of the finite element method involved here is the standard discretization and solution technique for both coupling of temperature-dependent physical properties in the thermo-hydraulic flow and for description of the multilayered structure of insulation, which may also be situated in the environment, such as soil or air. In order to describe the above problem in a standard manner, the complex thermo-hydraulic macroelement has been proposed. This element presents a combination of a standard hydraulic pipe element and one-dimensional thermal elements of the ANSYS code. The proposed approach is used to investigate temperature-dependent fluid properties and the role of the coupling in district heating pipelines