63490274 numerical coupling dem fem minecrush 2010 ragc v2
TRANSCRIPT
Nicolas Spogis, Ph.D.; Daniel Nasato, Eng.ESSS Brasil – www.esss.com.br
Rafael Angelo Tozzo, Eng.VALE – www.vale.com
Andrés González - M.Sc. ; Víctor SandovalESSS Chile – www.esss.cl
NUMERICAL COUPLING BETWEEN DEM (DISCRETE
ELEMENT METHOD) AND FEA (FINITE ELEMENTS
ANALYSIS).
Nicolas Spogis, Ph.D.Business Manager
E-mail: [email protected]
Daniel Nasato, Eng.Business Analyst
E-mail: [email protected]
Rafael Angelo Tozzo, Eng.Mechanical Engineering
E-mail: [email protected]
Authors
Andrés González, M.Sc.Account Manager
E-mail: [email protected]
Tel: +56 (2) 946 -1941
Cel: +56 (9) 9319-1576
Víctor SandovalNew Business Manager
E-mail: [email protected]
Tel: +56 (2) 946 -1941
Cel: +56 (9) 9319-1593
www.esss.cl www.vale.com
FlorianópolisBrazil
São PauloBrazil
Rio de JaneiroBrazil
SantiagoChile
ESSS at a Glance
ESSS develops, markets, and supports
engineering simulation software to shortening
and improve product development cycles in a
broad range of industries, by technology
transfer or providing simulation services.
WHAT WE DO
SINCE 1995 LOCATIONS
15 years providing the most comprehensive simulation solutions to the market.
NEW OFFICES
VALE at a Glance
• Vale is the world’s second-largest
mining and metal company in market
value, with assets of more than
US$ 100 billion.
• Vale is the global leader in the
production and export of iron ore.
• In 2006, Vale became the world’s
largest nickel producer after the
acquisition of the Canadian company
Inco.
• Vale is a global company
headquartered in Brazil, with a
workforce of over 100,000 employees,
including outsourced workers.
1º- Objectives
2º - DEM Method
3º - EDEM ANSYS Coupling
4º- Validation & Real Case
5º - Conclusions
Agenda
Objectives
• Develop an 1-way coupling between
Discrete Element Method (DEM) and
Finite Element Method (FEM).
• Propose a numerical validation to
evaluate the method accuracy.
• Simulate a transfer chute using the
developed method to solve a real
problem.
1º- Objectives
2º - DEM Method
3º - EDEM ANSYS Coupling
4º- Validation & Real Case
5º - Conclusions
• Governing equations for the translational and rotational
motion of particle i with mass mi and moment of inertia Ii:
DEM Method - Mathematics
• vi and ωi are the translational and angular velocities of particle i,
• Fcij and Mij are the contact force and torque acting on particle i by particle j
or walls,
• Fncik is the noncontact force acting on particle i by particle k or other
sources,
• Ffi is the particle–fluid interaction force on particle i,
• Fgi is the gravitational force.
• To detect contacts between particles and structure, EDEM splits the
geometry in triangular surface mesh (StL file format), a 3-dimensional
surface geometry;
• The surface is tessellated or broken down logically into a series of
small triangles (facets);
• Each facet is described by a perpendicular direction and three points
representing the vertices (corners) of the triangle.
DEM Contact Detection
Track each
particle and
boundary element
Detect contact
between elements
Calculate contact forces on
each particle
Calculate body
forces acting on
each particle:
gravity, fluid drag,
electrostatic, …..
Update particle acceleration
and velocity
Update particle and boundary
element positions
DEM Method - Basic Numerical Cycle
1º- Objectives
2º - DEM Method
3º - EDEM ANSYS Coupling
4º- Validation & Real Case
5º - Conclusions
EDEM-ANSYS Coupling
• EDEM was used as Discrete Element Method (DEM) tool and ANSYS
was used as Finite Element Method (FEM) tool.
EDEM-ANSYS 1-way couplingSetup ANSYS Model Run EDEM Model
Export EDEM
LoadsCreate Named
Surface
Interpolate Loads
Python Script
And ANSYS APDL
Solve and Evaluate
ANSYS Results
EDEM-ANSYS coupling methods
• 1-Way DEM-FEA
– Coupling - Steady State
– Static Structural Analysis
• 1-Way DEM-FEA
– Coupling - Transient
– Transient Structural Analysis
• 2-Way DEM-FEA
– Coupling - Transient
Developed
Under development
Force
Displacement
• Load is transferred from EDEM to ANSYS using a conservative
interpolation;
• Each element face is divided into n number of IP faces, where n is the
number of nodes on the face;
• IP faces are converted onto a two-dimensional polygon;
• Polygons on the sending side are intersected with the IP polygons on
the receiving side;
• The polygon intersection creates many overlapped areas used to
transfer loads between the two sides.
Interpolation Method
• During interpolation, the total force balance over the surface is
preserved.
• For loss less data transfer between particle and structural code, both
numerical models must be coincident in space
Interpolation Method
1º- Objectives
2º - DEM Method
3º - EDEM ANSYS Coupling
4º- Validation & Real Case
5º - Conclusions
Validation Tests
• It was built a small box with 1x1x1m in EDEM and it was created 2000
particles with 40mm diameter and 2500kg/m3 density;
• It was performed 3s of simulation to ensure that particles have no
velocity in Y direction;
• Total forces (X, Y and Z) and surface mesh nodes position are
exported from EDEM in a single time step.
• Force on Y direction calculated on EDEM was compared with
analytical results.
Validation Tests
• Test 1 - ANSYS coarse mesh,
EDEM coarse mesh
• Test 2 - ANSYS intermediate mesh,
EDEM coarse mesh
• Test 3 - ANSYS refined mesh,
EDEM coarse mesh
Analytical EDEM force Test 1 - Coarse Test 2 - Intermediate Test 3 - Refined
Force Y (N) 1643,8 1645,8 1575,2 1617,6 1663,5
Error % 0,1 4,3 1,7 1,1
• Case Vale – Mina de Brucutu
Industrial Application
Modeling of ore flows and loads on transfer‐chutes.
A case study for Vale Brucutuusing EDEM and Ansys.
Geometry
•Geometry directly imported
from CAD on ACIS (.sat)
format.
•Simulation:
•Conveyor belt
•Transfer chute
•Vibrating screens
•Dynamics:
•Sinusoidal translation
•Sinusoidal rotation
•Moving plane (for belt)
• Mass flow: 8492 t/h
• Conveyor velocity: 3.52 m/s
• Particle diameter: 25 mm
• Particle shape: Single sphere
• Dynamic repose angle: 20˚
• Static repose angle: 30˚
• Moisture: 8%
• Iron Ore density: 2500kg/m³
• Ore / Ore Interaction:
• Coeff. of Restitution: 0.4
• Static friction: 0.65
• Rolling friction: 0.1
• Ore / Belt Interaction (rubber):
• Coeff. of Restitution 0.3
• Static friction: 0.6
• Rolling friction: 0.05
• Ore / Structure Interaction (steel)
• Coeff. of Restitution 0.3
• Static friction: 0.5
• Rolling friction: 0.05
Material properties
EDEM Factory
•Mass Flow:
•8492 t/h – 2.3589 ton/s
•Aprox. 30000 particles/s
Conveyor dynamics
Belt Angle Vtotal Vy Vz
Slice 1 18,919 3,520 m/s -3,330 m/s 1,141 m/s
Slice 2 19,658 3,520 m/s -3,315 m/s 1,184 m/s
Slice 3 9,890 3,520 m/s -3,468 m/s 0,605 m/s
Cylinder Radius 0,659 m
Perimeter 4,141 m
Vtotal 2,816 m/s
RPS 0,680
RPM 40,805
Screen dynamics
x y z
Right Screen 6,87 7,92994 11,9179 996 16,6 0,5697
Left Screen 2,086 7,8384 12,0042 996 16,6 0,4988
6 DOF centerRPM Hz Angle
EDEM Results
EDEM Results
High impact velocities zones – Wear and structural problems.
EDEM Results
Screen force distribution
High impact velocities zones
(up to 7 m/s) on screen.
Wear and structural problems.
High forces on chute discharge.
Unbalanced forces
Unbalanced forces on screen generated by
wrong chute discharge.
Time varying forces
-8000,00
-6000,00
-4000,00
-2000,00
0,00
2000,00
4000,00
6000,00
0,00 5,00 10,00 15,00 20,00 25,00 30,00
Total Force X (N)
-15000,00
-10000,00
-5000,00
0,00
5000,00
10000,00
15000,00
20000,00
0,00 5,00 10,00 15,00 20,00 25,00 30,00
Total Force Y (N)
-140000,00
-120000,00
-100000,00
-80000,00
-60000,00
-40000,00
-20000,00
0,00
20000,00
0,00 5,00 10,00 15,00 20,00 25,00 30,00
Total Force Z (N)
0
10000
20000
30000
40000
50000
60000
1 2 3 4 5 6
Tota
l Fo
rce
(N
)
X direction bin group
Total force on screen width
30.05
30.10
30.15
30.20
30.25
30.30
30.35
30.40
30.45
30.50
• Unbalanced forces; – Picks reaches 20 times higher forces
between one extreme to another.
Force Distribution
• EDEM can split the domain into small fraction (Bins) to do local analysis;– Domain was split into 8 regions in X-
direction, in order to investigate unbalanced forces.
EDEM-ANSYS coupling – Conservative
Interpolation
The developed scripts and macros automatically interpolates
EDEM forces (normal and tangential) on the structural
elements.
Total Deformation Equivalent Strain
Static Structural Analysis
The Static Analysis performed shows stresses
& Strains under the yield limit OK
Modal Analysis
Mode 1 - 3.3647 Hz Mode 2 - 6.874 Hz Mode 3 - 14.121 Hz
Mode 4 - 21.454 Hz Mode 5 - 25.309 Hz Mode 6 - 26.261 Hz
FFT – Fast Fourier TransformationMode 1 - 3.3647 Hz
-8000.00
-6000.00
-4000.00
-2000.00
0.00
2000.00
4000.00
6000.00
0.00 5.00 10.00 15.00 20.00 25.00 30.00
Total Force X (N)
-15000.00
-10000.00
-5000.00
0.00
5000.00
10000.00
15000.00
20000.00
0.00 5.00 10.00 15.00 20.00 25.00 30.00
Total Force Y (N)
-140000.00
-120000.00
-100000.00
-80000.00
-60000.00
-40000.00
-20000.00
0.00
20000.00
0.00 5.00 10.00 15.00 20.00 25.00 30.00
Total Force Z (N)
3.2031
3.3984
0
50000
100000
150000
200000
250000
300000
350000
400000
450000
0 1 2 3 4 5
FFT Magnitude X
3.2031
3.3984
3.5938
0
100000
200000
300000
400000
500000
600000
700000
800000
0 1 2 3 4 5
FFT Magnitude Y
3.203125
3.359375
0
500000
1000000
1500000
2000000
2500000
3000000
3500000
4000000
4500000
5000000
0 1 2 3 4 5
FFT Magnitude Z
RESONANCE !!!
1º- Objectives
2º - DEM Method
3º - EDEM ANSYS Coupling
4º- Validation & Real Case
5º - Conclusions
Bulk Handling & Structural Problems?!...
Coupled SIMULATION can solve them!Structural Problems
(FEA Simulation)Bulk Handling Problems
(DEM Simulation)Coupled Problems
Static & Dynamic effects of ore in equipment
Material Degradation & Segregation
Unbalanced Load
Inadequate SupportsChute Clogging & Uneven Feed
High Ore impact in the equipment Structure
Fatigue Cracking Conveyor Belt misalignmentEquipment Weight reduction Energy Efficiency
Wrong Springs (screens) Screen Performance
Mineral Crushing(Particle Breakage)
Spillage & Dust
Rats Holes in Discharges
Conclusions
DEM can solve industrial bulk
material handling problems.
FEA can solve structural analysis
problems.
DEM-FEA coupling can give the right
structure for the
best particle flow!