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Incomplete instruction for Model Library example (Sliding Wedge)
Posted 2012/11/14 4:28 GMT-5 Studies & Solvers, Structural Mechanics Version 4.3a 2 Replies
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I'm trying to create a model from Model Library, using only pdf instruction. The model is Sliding Wedge (Structural Mechanics Module/Contact and Friction/sliding_wedge). The problem is, that a model built exactly according to given instruction is not converging.
After comparing my model (attached to this message) with the one included in Model Library, I noticed that the information about manual scaling of dependent variables is missing in pdf instruction. But what is worse - I don't know how can I set scaling so that it is the same as in the reference model (from Model Library).
In my model, automatically created solver contains 'Dependent Variables 1' node, which consists of only one field - 'mod1.u'. In Model Library model, there are many more fields (like, for example, 'mod1.solid.Tt_ap1').
So, my question is - what should I do to add these fields to Dependent Variables node?
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for me it looks like you have not defined any contact area, you need to select the contact pair te get it active and turn on the selection pairs on top of the Contact node tab.
Then I do not fully understand your body load cases, but OK those are short-cuts, normally a body load is a distributed load, and the easiest is to write "-g_const*solid.rho" along Y in 2D, where "_const" is COMSOL's internal name for 9.81[m/s^2] and rho is the density, this gives a "load density of the correct value, and COMSOL is mapping the material density for you, useful in case of several different materials
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Good luck
Ivar
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Some comments:
1. As Ivar points out, you have missed item 3 in
Contact 1
1 In the Model Builder window, right-click Solid Mechanics and choose Pairs>Contact.
2 In the Contact settings window, locate the Pair Selection section.
3 In the Pairs list, select Contact Pair 1.
As a consequence of this, when you solved the problem, you got a solver sequence for a problem without contact.
If you now go back and select the contact pair, you will still not be able to run the problem, since the solver sequence will not be correct. So before solving again:
Go to Solver configurations, Right click, and select Delete Solvers.
Now you can solve the study again, with a proper solver sequence. The variable scaling will be as in the model you opened, since these are the default values.
2. About the gravity: This is a benchmark model, and does not contain any physical density. So the value given in the model is taken from the reference.
Regards,
Henrik