Marc 有限元收敛讲义

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Nonlinear Analysis Guidelines
Perform and scrutinise the results from a static linear analysis to check the integrity and behaviour of the basic model. If the nonlinear model already exists…
carried out 3. To prevent expensive “surprises” at the end of a project
Single element tests are preferable (where possible) since it is so much quicker and easier to verify the input and to evaluate the response with only a few degrees of freedom
SECTION 12
RESOLVING CONVERGENCE PROBLEMS
PMMAAATRR31122800,1,S–LeeCcctoitounres3e4, ,NMMoatarecrsch,h2S20e00c01.112, November 2005
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PMMAAATRR31122800,1,S–LeeCcctoitounres3e4, ,NMMoatarecrsch,h2S20e00c01.112, November 2005
2. The MARC Demonstration Problem manual (volume E). It is in Marc data file format only. The data files associated with this manual can be located in the Marc installation directory
reached 3. For geometrically nonlinear analyses turn off Large Displacement– as well as any
large strain material options
Add each of the nonlinearities one by one to determine their effect on the solution and its convergence behaviour. For instance, start with contact, adding next any geometric nonlinearity and then finally any material nonlinearity, etc.
There are a number of sources of examples and benchmarks available that may help in this regard…
1. The MARC User Guide manual. This contains an increasing amount of worked examples written with the express intention of demonstrating the use of the facilities clearly
PMMAAATRR31122800,1,S–LeeCcctoitounres3e4, ,NMMoatarecrsch,h2S20e00c01.112, November 2005
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Nonlinear Analysis Guidelines
Convergence of a nonlinear problem is mostly not simply to do with the convergence tolerance values or the criteria specified..it is an overall issue of model integrity and representation of reality
It is strongly recommended that small tests be performed to gain experience of unknown (to you) element and solution types:
1. To understand its limitations 2. To ensure that it does provide the required behaviour for the actual simulation to be
Βιβλιοθήκη Baidu3. The NAFEMS suite of examples. Further information is available on their website (www.nafems.org)
PMMAAATRR31122800,1,S–LeeCcctoitounres3e4, ,NMMoatarecrsch,h2S20e00c01.112, November 2005
1. For contact analyses, this would mean changing all contact conditions to GLUED 2. For material nonlinearity simply increase the failure criteria so that it cannot be
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Overview
Nonlinear Analysis Guidelines Information Available to Help Analysis Troubleshooting: General Analysis Troubleshooting: Criteria
Behaviour Analysis Troubleshooting: EXIT Numbers