Think I've found the error - we need to increase fvar to 100 say and increase the number of n_steps = 100.
I believe the problem is now solved. Next step is to compare the output to actual data and code the tensile failure checks.
a
On Mon, Jan 24, 2011 at 12:38 PM, Andre Smit <freev...@gmail.com> wrote:
Robert - sorry for all these posts but I'm making corrections as I go along.
Please disregard the previous code link, I've corrected as shown at [1]. The force-displacement curve is now non-linear as one would expect. Still bothering me is the change in moduli for the same rate. If the displacement interval (dt) is -0.1 and the rate is abs(dt), one should get the same strain rate if dt is -0.01, but it increases. Still trying to track down this error.
[1] http://paste.pocoo.org/show/326129/
On Mon, Jan 24, 2011 at 11:26 AM, Andre Smit <freev...@gmail.com>wrote:
I've revised the code as shown in [1] to illustrate what I mean by assigning smin at convergence. It is interesting to see that the problem still converges when the elements start to fail!
[1] http://paste.pocoo.org/show/326090/
On Mon, Jan 24, 2011 at 9:08 AM, Robert Cimrman <cimr...@ntc.zcu.cz>wrote:
On Mon, 24 Jan 2011, Andre Smit wrote:
Thanks
works like a charm! Two comments:
- Since the model is 1/8 of actual the deformation rate is half of actual test. So the strain rate in the Fc, Ft and Ec functions should be doubled: e *= 2 # With 1/8 model the applied deformation rate is half of actual test
Yes, modify it as needed :)
- Don't you think failed elements (smin) should only be assigned at the
end of an iteration run and not during sub-iterations.
I do not know - if you do not change the stiffness in sub-iterations, then nothing changes after the first one, and there is no need for them, right?
r.
On Mon, Jan 24, 2011 at 2:05 AM, Robert Cimrman <cimr...@ntc.zcu.cz> wrote: ok, so the patch is in... the script should work out-of-the-box.
r.On Sat, 22 Jan 2011, Robert Cimrman wrote:
I have overhauled the script, so that there are no globals, subiterations can be ended as needed etc. The traction() function is removed, the loading displacement is given simply by value. I hope it does what you intended. It needs a patch to TimeStepper, that I will be able to upload first on Monday, so either just look at it, or fix it yourself... :) r. ----- Reply message ----- From: "Andre Smit" <freev...@gmail.com> To: <sfepy...@googlegroups.com> Subject: Conference Date: Fri, Jan 21, 2011 02:47 Robert I believe I've sorted out the oscillation problem, which was a bug in the code. I've pasted the latest version at [1] that now converges tightly after 3 or 4 iterations. I have a few comments. As you will see: a) I'm runnng the solver repeatedly with increasing displacements. This was mainly because I'm unable to change the displacement variable (disp) in traction() outside of the function. Globals and lists didn't work for me here. b) To overcome this obstacle, the displacement for each solver/displacement cycle is saved to file and read from disk in traction(). c) I iterate the problem until the force converges and then increment the displacement. d) The element stiffness matrix (Ele) is saved to file and loaded at the start of the subsequent displacement interval. Comments: 1) I considered adding a variable to ts, say ts.disp and adding the displacement to that, making it available in traction. I'm sure there is a better way though. 2) I also cannot terminate the ts loop and am forced to run through all ts.n_steps. This is a problem since the forces converge at different number of steps at which point I would like the loop to end. [1] http://paste.pocoo.org/show/324169/ Andre On Wed, Jan 19, 2011 at 10:22 AM, Robert Cimrman <cimr...@ntc.zcu.cz> wrote: On Wed, 19 Jan 2011, Andre Smit wrote: Robert - I'm trying to change the displacement (disp) in the traction function when the force stabilizes but for some reason the scope of disp within traction() appears different to that within calc_force(), even though disp is defined as global. Any ideas? old_force = 0 def calc_force(pb, ts, state): global disp,old_force d = state() pb.remove_bcs() f = pb.evaluator.eval_residual(d) pb.time_update() f.shape = (pb.domain.mesh.n_nod, 3) p = [] for n in pb.domain.regions['Top'].vertices[0]: p.append(f[n][2]) p = nm.array(p) if abs(old_force-p.sum()) < fvar: my_output(disp,",",p.sum()) disp -= ddisp old_force=p.sum() def traction(ts, coors, bc=None): global disp #disp = -(ts.dt*(ts.step+1)) print "traction disp: ", disp val = nm.empty_like(coors[:,0]) val.fill(disp) return val I would use brute force: globals()['disp'] = ... You cannot really change value of a global that is immutable (IMHO)... A common idiom is to use list instead, like: disp = [0] def traction(ts, coors, bc=None): disp[0] = ... What is the meaning of 'smix' stiffness, for strain rate zero? I'm not sure. That might be the problem causing the oscillations... r. -- You received this message because you are subscribed to the Google Groups "sfepy-devel" group. To post to this group, send email to sfepy...@googlegroups.com. To unsubscribe from this group, send email to sfepy-devel...@googlegroups.com<sfepy-devel%...@googlegroups.com>. For more options, visit this group at http://groups.google.com/group/sfepy-devel?hl=en.
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