*heading
Impact of two identical spheres with a constant normal velocity and opposite spin but varying angular velocities 
**
*preprint, model=yes, history=yes
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*parameter
angular_speed=0.175
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**NODES
**
*node,nset=qa_test
1, -0.10000005, 0.0, -0.5
2, 0.10000005, 0.0, -0.5
3, -0.10000005, 0.0, 0.5
4, 0.10000005, 0.0, 0.5
**
**NODE SETS
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*nset, nset=Al_alloy
1, 2
*nset, nset=Copper
3, 4
*nset, nset=dem
1, 2, 3, 4
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**ELEMENTS and ELEMENT SETS
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*element, type=pd3d, elset=Al_alloy
1, 1
2, 2
*element, type=pd3d, elset=Copper
3, 3
4, 4
*elset, elset=dem
1, 2, 3, 4
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**SECTIONS 
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*discrete section, elset=Al_alloy,shape=sphere,density=2700
0.1
*discrete elasticity
70e9, 0.33
*discrete section, elset=Copper,shape=sphere,density=8900
0.1
*discrete elasticity
120e9, 0.35
*section control, name=autodem-1
 
 
 
 
 0.1, 0.1, 0.1, 0.1, 0.1, 0.1 
*section control, name=autodem-2
 
 
 
 
 0.1, 0.1, 0.1, 0.1, 0.1, 0.1  
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**SURFACES
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*surface, type=element, name=Al_alloy_surf
Al_alloy,
*surface, type=element, name=Copper_surf
Copper, 
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**SURFACE INTERACTION 
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*surface interaction, name=Al_alloy_int
*friction
0.4
*surface behavior, pressure-overclosure=Hertz
1e10
*contact damping, definition=damping coefficient
0.0
*surface interaction, name=Copper_int
*friction
0.4
*surface behavior, pressure-overclosure=Hertz
1e10
*contact damping, definition=damping coefficient
0.0
**
**INITIAL CONDITIONS
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*initial conditions, type=velocity
1, 1, 0.2
2, 1, -0.2
3, 1, 0.2
4, 1, -0.2
1, 5, <angular_speed>
2, 5, -<angular_speed>
3, 5, <angular_speed>
4, 5,-<angular_speed>
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**STEP
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*step
*dynamic, explicit, element by element
, 8e-4
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**CONTACT DEFINITIONS
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*contact
*contact inclusions
Al_alloy_surf, Al_alloy_surf
Copper_surf, Copper_surf
*contact property assignment
Al_alloy_surf, Al_alloy_surf, Al_alloy_int
Copper_surf, Copper_surf, Copper_int
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**HISTORY OUTPUT
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*output, history, freq=1
*node output, nset=qa_test
V, VR
*node output, nset=Al_alloy
V, VR
*node output, nset=Copper
V, VR
*energy output, variable=all
*INCREMENTATION OUTPUT,var=all
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**FIELD OUTPUT
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*output, field, timeinterval=4e-4
*node output, nset=dem
U,V,A
*contact output
CFORCE
*end step