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Where to Start With Nonlinear Analysis?

The online documentation in each release kit contains a number of useful introductory sections which may be located by searching for the following (note that the searches are case sensitive):
  • "About Nonlinear Analysis"
  • "2.3 Nonlinear Static Analysis". Use the forward menu button (>>) to page through the whole of section 2.3
  • "Analysis CONTROL"

Further, more specific and detailed information on nonlinear analyses is available as follows

Iterative solution procedures A description of nonlinear iterative methods including Newton-Raphson,  line search procedures and separate iterative loops for contact analyses
Load incrementation procedures A description of load incrementation methods including manual, automatic, mixed, arc-length procedures, automatic step reduction, termination, convergence and output
Nonlinear control parameters A description of the parameters, their meaning and typical values found in the nonlinear control forms.

A description of the parameters on the nonlinear control dialog. Wherever possible, the default values of the nonlinear control properties should be used - they represent generally applicable settings that automatically activate additional facilities as required

Load case and load increment Answers the question "what is the difference between a load increment and a load case?"
Interpretation of the nonlinear log file The nonlinear log file is of immense help in ascertaining whether the nonlinear analysis is progressing well. If it is not, it gives valuable information to help locate the cause of the problem
Modified Newton-Raphson A description of the iterative solution method called the modified Newton-Raphson technique
Current stiffness parameter A description of the meaning of the nonlinear log file parameter CSTIF, including its definition and how it helps interpret what is happening in the nonlinear analysis
Residual convergence criterion Answers the question "what is the residual norm (RDNRM) and what value should be used?"
Loading procedures Describes the difference between automatic and manual load incrementation procedures and demonstrates, with examples, how to mix them together to obtain any required loading history
Elasto-Plastic material model description A detailed description of the current elasto-plastic material models available together with their hardening types


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