Convergence for Initial Interpenetration?

JonathanHodgson — Wed, 19 Dec 2018 14:33:41 GMT

Hi gurus,

How can I improve convergence for initial interpenetration?

My model of a piston seal solves without Large Displacements; but with that enabled (required for hyperelastic material, and I think for correct behaviour) it gives the following failure:

*** A fatal error has occurred. ***
The nonlinear iteration did not converge for the
time value:  0.00000e+00

   o The model may have a buckling mode with a load factor
     smaller than this value. You may determine the smallest
     (linear) buckling load factor by running a buckling
     analysis.

   o The deformations may be large enough that you must
     further refine the mesh. To locate potential problem
     areas, it may help to run an analysis with reduced
     loads and examine the deformed shape of the model.

   o The model may have a static instability.

   o  It is possible that the load is too large for the model's 
      material or the model is insufficiently constrained. Check 
      the constraints and material properties, or reduce the maximum load.

This is for load factor 0 so I can't reduce the load any further!

I've tried reducing the element size, with no improvement. Any other suggestions?

Re: Convergence for Initial Interpenetration?

skunks — Wed, 19 Dec 2018 14:47:24 GMT

2D axisymmetric? Initial Interpenetration?

You need independed mode of mechanica

Re: Convergence for Initial Interpenetration?

JonathanHodgson — Wed, 19 Dec 2018 14:47:27 GMT

With linear material and LDA I got it to run for several iterations before failing (instead of failing immediately or after one iteration) by reducing Poisson's Ratio to 0.4 from 0.49; but for a hyperelastic material there appears to be no entry for Poisson's Ratio.

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Convergence for Initial Interpenetration?

Re: Convergence for Initial Interpenetration?

Re: Convergence for Initial Interpenetration?