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*MASS DIFFUSION
Transient or steady-state uncoupled mass diffusion analysis.

This option is used to control uncoupled transient or steady-state mass diffusion analysis.

Products: Abaqus/Standard  Abaqus/CAE  

Type: History data

Level: Step

Abaqus/CAE: Step module

Reference:

Optional parameters:

DCMAX

Set this parameter equal to the maximum normalized concentration change to be allowed in an increment. Abaqus/Standard will restrict the time step to ensure that this value will not be exceeded at any node (except nodes with boundary conditions) during any increment of the analysis. If the DCMAX parameter is omitted, fixed time increments will be used.

END

Set END=PERIOD (default) to analyze the entire time period specified on the data line. Set END=SS to end the analysis when steady state is reached.

STEADY STATE

Include this parameter to choose steady-state analysis. Transient analysis is assumed if this parameter is omitted.

Data line to define time stepping in a mass diffusion analysis: 

First (and only) line:

  1. Time step. If automatic stepping is used, this value should be a reasonable suggestion for the initial step and will be adjusted as necessary.

  2. Time period. If END=SS is chosen, the step ends when steady state is reached or after this time period, whichever occurs first.

  3. Minimum time increment allowed. If Abaqus/Standard finds it needs a smaller time increment than this value, the analysis is terminated. If no value is given, Abaqus/Standard sets the minimum increment to the minimum of 0.8 times the suggested initial time step (the first data item on this line) and 10–5 times the time period (the second data item on this line). If a value is given, Abaqus/Standard will use the minimum of the given value and 0.8 times the suggested initial time step.

  4. Maximum time increment. If this value is omitted, no upper limit is imposed. This value is used only for automatic time incrementation.

  5. Rate of change of normalized concentration (normalized concentration per time) used to define steady state; only needed if END=SS is chosen. When all nodal normalized concentrations are changing at less than this rate, the solution terminates.