Recent and future developments in LS-DYNA -in Discrete element (DEM,DES)

Transcription

1 Recent and future developments in LS-DYNA -in Discrete element (DEM,DES) David Aspenberg 1, Nils Karajan 2 1 DYNAmore Nordic, Linköping, Sweden 2 DYNAmore GmbH, Stuttgart, Germany

2 Outline Introduction Applications Granular media Creating a model aspects Nodes and elements Generating and de-activating particles Control contact between particles Control contact between particles and structure Bonds between particles, linear and non-linear Post-processing View particles as points or smooth Visualize: contact forces between particles Massflows contact forces with surfaces wear DYNAmore Nordic Information Day

3 Applications DEM is usually applied in the fields of Storage Silos Piles Transportation Conveyor belts/ screws Pumps Courtesy Kirk Fraser (Predictive Engineering) DYNAmore Nordic Information Day

4 Applications DEM is usually applied in the fields of Processing Mixing drum mixer Shear mixer paddle mixer Courtesy Joseph Kitching (P&G) DYNAmore Nordic Information Day

5 Applications DEM is usually applied in the fields of Filling and packaging simulation Courtesy Kirk Fraser (Predictive Engineering) DYNAmore Nordic Information Day

6 Applications DEM is usually applied in the fields of Tire simulation on sand or gravel (slow) DYNAmore Nordic Information Day

7 Applications DEM is usually applied in the fields of Tire simulation on sand or gravel (fast) DYNAmore Nordic Information Day

8 Introduction Applications of DEM Materials that consist of discrete particles liquids and solutions, for instance of sugar or proteins bulk materials in storage silos, like cereal granular matter, like sand powders, like toner Blocky or jointed rock masses Typical industries using DEM are Agriculture and food handling Chemical Civil Engineering Oil and gas Mining Mineral processing Pharmaceutical Powder metallurgy Jelly beans, sesamy seeds, coffee beans, sand, coarse gravel, medical pills, fertilizers, coal Numerical simulations could help in design of: Storage Silos, Piles Transportation Conveyor belts, screws, pumps Processing Sorting, mixing, segregation Filling Hopper/ funnel flow DYNAmore Nordic Information Day

9 DEM Principle Rigid spherical particles with mass, radius and six degrees of freedom that follow Newton s laws of motion and interact through contact. Initial positions and velocities Collision Detection Contact Force and Torque Calculation t n+1 = t n + dt Newton s 2 nd Law a = F / m Calculate new velocities & positions Output Data DYNAmore Nordic Information Day

10 DEM Introduction Density can be set to unity in generation of particles, and the properties can be scaled later using e.g. *MAT_ELASTIC. (I.e., by using the _VOLUME option, it is not the actual mass and inertia that is presented in the *ELEMENT_DISCRETE_SPHERE_VOLUME keyword.) *ELEMENT_DISCRETE_SPHERE_VOLUME $ $# NID PID MASS INERTIA RADIUS *NODE $ $# NID X Y Z TC RC DYNAmore Nordic Information Day

11 Generating packed particles in LS-PrePost procedure Select volume and set radius distributions. Click create. Inspect results and accept. View final result. DYNAmore Nordic Information Day

12 De-activating particles during simulation By defining an active region for the particles, the particles are diregarded as they leave this volume. Helps the bucket sort to achieve speed in contact algorithm. Recommended to use, always! DYNAmore Nordic Information Day

13 DE to DE interactions Interactions between discrete elements are controlled by the *CONTROL_DISCRETE_ELEMENT keyword. *CONTROL_DISCRETE_ELEMENT $ $# NDAMP TDAMP FRIC FRICR NORMK SHEARK CAP VTK $# GAMMA VOL ANG DYNAmore Nordic Information Day

14 Capillary forces example Funnel Flow - Variation of the parameters for cohesion and friction $ RHO 0.80E E E E-6 1.0E-6 P-P Fric P-P FricR P-W FricS P-W FricD CAP Gamma E E-6 7.2E-8 $ foamed clay dry sand wet sand fresh concrete water wet dry DYNAmore Nordic Information Day

15 Several DES materials Multiple mixtures of materials with different properties that are modelled with DES can be handled by setting the DE properties per part. DYNAmore Nordic Information Day

16 DE to surface interaction Classic contact New DE contact Friction force is applied at the perimeter. Possibility to define transportation belt velocity via LCV. Optional calculation of wear using Archard s law. DYNAmore Nordic Information Day

17 DE to surface interaction Developed especially for discrete element to Lagrangean structure interaction Archard s Wear Law. If WEARC > 0 then wear depth h on the shell surface is calculated with Wear depth h is output to the interface force file *DATABASE_BINARY_DEMFOR lsdyna i=input.k dem=interface_force_file DYNAmore Nordic Information Day

18 Coupling to other solvers DE to ALE interaction (*ALE_COUPLING_NODAL_DRAG). New feature (experimental). Coupling to SPH (*DEFINE_SPH_DE_COUPLING). New feature (experimental). DYNAmore Nordic Information Day

19 Post processing using LS-PrePost The visualization of the particles is strongly improved by the smooth option DYNAmore Nordic Information Day

20 Post processing using LS-PrePost ASCII database to measure the mass flow of a particle system To be used with *DATABASE_DEMASSFLOW to control the output frequency. *DEFINE_DE_MASSFLOW_PLANE $# SLAVE MASTER STYPE MTYPE *DATABASE_RCFORC to generate a file named demrcf Output frequency needs to be defined Contains forces acting on DES Same format as the rcforc file DYNAmore Nordic Information Day

21 Post processing using LS-PrePost Fringe plotting General binary database d3plot for general visualization Fringe particle-particle contact forces to identify force chains. DEM binary database dem_interface_force. Obtained by *DATABASE_BINARY_DEMFOR and dem= on the commandline Only the master side is written to the database Both fringe plot and history plot can be done resultant interface force surface wear (still written as relative interface velocity) DYNAmore Nordic Information Day

22 Thank you! Your LS-DYNA distributor and more DYNAmore Nordic Information Day