mechanical nonlin 13.0 ws 02b restart

8/12/2019 Mechanical Nonlin 13.0 WS 02B Restart

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Customer Training Material

or s op

Performin a Restart

Structural Nonlinearities

WS2B-1ANSYS, Inc. Proprietary

2010 ANSYS, Inc. All rights reserved.Release 13.0

December 2010


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ANSYS Mechanical Structural Nonlinearities

Customer Training MaterialWorkshop 2B: Performing a Restart

Goal

Use Restart Control technology to resume an unconverged solution

after making necessary adjustments to remedy the nonconvergence

Model Description

Same as Worksho 2A



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Customer Training Material Workshop 2B: Performing a Restart

Continuing with same model from

Workshop 2A, highlight the Force

load and increase the magnitude to

From Analysis Settings, open Restart

Controls and request all substeps be savedas restart points.



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After a few warnings, errors and bisections, the run fails to converge.

Review the Solution Information Solver Output and Force Convergence plot



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xam ne e o ver u pu ex

Note the warnings and errors recorded early in the run that indicate excessiveelement distortion and recommend more substeps as one possible remedy.



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eca a e e au or ep on ro was

used

For this application, with large deflection

turned ON this resulted in the solver

automatically trying to solve this problem with

one substep initially, allowing up to 10

(maximum) if necessary.

Towards the end of the run, the Automatic

Time Stepping program had reduced the

timestep size down to the minimum value. . ,

downward is available.



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Return to Analysis Settings

set Restart Type to Manual

set Current Restart Point to the last successfully

,

nonconvergence would be to simply enlarge the

time step range from the default values.

Turn Auto Time Stepping ON and adjust the range as

shown

10 is a reasonable value to restart initially

100 is just a guess based on experience.

The ran e is hi hl roblem de endent. Other

models might require many more substeps.



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Customer Training Material Workshop 2B: Performing a Restart , x u .

Highlight the Solution information Branch and

Notice the additional bisections that lead to adifferent convergence pattern and ultimately a

successfully completed run



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Customer Training Material Workshop 2A: Large Deflection

ev ew e s ress an sp acemen

results as before.

reacted out at the fixed support



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For comparison, clear the generated data and re-

solve the model from the beginning.

Notice the model now solves with only one bisection

,

more then 50%!) underscoring the importance of

taking advantage of auto time stepping technology

with a sufficient range in nonlinear problems.



December 2010

mechanical nonlin 13.0 ws 02b restart

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