Learning Forum

[Himanshi]

Dear Sir,

I am modeling a wall in ANSYS APDL in which sliding occurs as soon as I apply the displacement as I am doing displacement control analysis. I am using friction model to define interface property.

But In Friction model, which parameter is used to control the stiffness before sliding??

please anyone help me.

[peteroznewman]

I'm not sure what you mean by "stiffness". You can read more about friction in the ANSYS Help.

The parameter that controls the tangential force limit when the contact changes from sticking to sliding is MU.  In the table below, MU depends on temperature.

TB,FRIC,1,2,,ISO     ! Activate isotropic friction model

TBTEMP,100.0         ! Define first temperature

TBDATA,1,MU          ! Define coefficient of friction at temp 100.0

TBTEMP,200.0         ! Define second temperature

TBDATA,1,MU          ! Define coefficient of friction at temp 200.0

[Himanshi]

Thanks for your early reply.

I have read the topics but in the figure 2 attached, if delta s is the displacement at which sliding starts in the model then stiffness of force-displacement curve before delta s can be controlled by which parameter??

Because in my model as soon as I apply the lateral displacement, the layer defined by friction model and no separation sliding permitted contact starts sliding, which does not happen in usual friction case. As model should start sliding after some time i.e. after this delta s displacement.

In advance Thank you again

 

[peteroznewman]

The material property that defines the shear deformation that you labeled Delta sub s is the shear modulus G.

If you have two blocks, as long as the shearing force V is < mu*Fnormal, the blocks will shear without the frictional interface sliding.

[Himanshi]

 Thanks sir for these detail explanation.

But, in my model this is what is not happening, before any shear deformation the sliding (blocks displace relative to each other, can be seen from fig 1) occurs at the start of application of lateral displacement. I don't understand how to control these phenomenon.

As I want my model to behave similar to what you have explained.

Please help me with these as how to control the displacement of sliding layer before a certain value of lateral displacement.

Thank you

[peteroznewman]

Is Gravity the only load pressing the top layer down onto the next layer?

Did you do a hand calculation of the shear force that can be applied before the sliding starts?

Did you do a hand calculation of the shear deformation you get before the sliding starts?

[Himanshi]

Yes Sir,

Gravity load acts on the top of the beam and self-weight of each element is considered.

I have done hand calculation on the basis of live load+self-weight acting on the sliding layer, as per my calculation shear deformation is 3.3 mm but in my model relative displacement between the sliding layer start  from 0.1 mm onward, which shouldn't happen. And I want to understand why is it happening.

Is it because of no separation contact behavior (keyopt (12) = 2) and friction model I applied to that interface. What phenomenon is happening over there, this I want to understand, so that I can able to explain about my model behavior.

 

Thank you sir for your precious time and this much help.