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## #1 2018-04-05 02:55:52

naba
Member
Registered: 2018-03-05
Posts: 4

### Modelling of a Coulomb Friction

I want to create a friction model in code aster which is later connected in series with SDOF system. The governing equation for the friction model is
F = m.g.2/pi.arctan(ud/c)
where,
F = force
m= mass
g = acceleration of gravity
ud= velocity
c = reference velocity (constant)

Furthermore, the equation of motion of the total system after connecting it with SDOF system when excited by ground acceleration (uddg) becomes,
m.udd + cs. ud + ks. u + m.g.2/pi.arctan(ud/c) = -m.uddg
where,
udd = acceleration
cs = damping
ks = stiffness
u = displacement
. represents multiplication.

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## #2 2018-04-05 20:07:56

dbpatankar
Member
From: Roorkee, Uttarakhand, India
Registered: 2010-05-22
Posts: 177

### Re: Modelling of a Coulomb Friction

When you have the governing differential equation and its a SDOF system, why dont you just use an appropriate time marching scheme and solve it?

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## #3 2018-04-06 01:38:28

naba
Member
Registered: 2018-03-05
Posts: 4

### Re: Modelling of a Coulomb Friction

Thank you so much for the reply. But I'm sorry for not being clear to my question. I've already made a program to solve the model itself exactly according to your suggestion and it is working perfectly.
So to the addition of my previous question, ultimately I want to combine 'Coulomb Friction' model with 3D FEM model. In that case, having a (discrete) element of such model would be a great advantage. I'm just wondering if I can develop such element in code aster or not.

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