**process fatigue_EE

Description

This post-computation is used to determine component life by a criterion dependent on a strain measure (elastic and plastic). The critical variable is the amplitude of the strain for uni-axial loading, with a generalization for multi-dimensional loading (see the post processor range). If the loading is well known, the user can give simply the output “maps” necessary to calculate this amplitude (mode n1 n2 in **output_number). In the other case, a period of loading must be input (mode n1-n2 in **output_number).

The strain amplitude is denoted . The post computation will generate a single output record for the total loading history input. This is the number of cycles to failure, given by:

\[{\bf DEQ} = A\;{N_f}^{-1/\alpha} + B\;{N_f}^{-1/\beta}\]

Syntax

**process fatigue_EE \(~\,\) *var name \(~\,\) [ *type scalar | tensor ] \(~\,\) [ *scale lin | log] \(~\,\) [ *range section]

name is the name of the subject variable of the computation.

For multi-dimensional loading the amplitude calculation will be made using a range type post-computation. In order to be able to input options to the range processor, the user can give a section number for that user input after the *range keyword.

The computation requires input of the coefficients A and B, alpha and beta in the material file.

Output is given as number of cycles to failure in the variable NF_EE. If the user specifies a logarithmic scale using the *scale option, the output variable will be LNF_EE.

Example

**process fatigue_EE
  *var sig
  *scale log

% The following syntax must be used in the material file :
**process fatigue_EE
   A       3.
   alpha   3.
   B       1.7
   beta    1.5