help Rec12
  ABAQUS stress invariant output to MATLAB
  
  Syntax
      #Rec# = Fil2str('*.fil');
      #out# = Rec12(#Rec#)
 
  Description
      Read stress invariant output from the results (*.fil) file generated
      from the ABAQUS finite element software. The asterisk (*) is replaced
      by the name of the results file. The record key for stress invariant
      output is 12 (only in ABAQUS/Standard). See section "Results file
      output format" in ABAQUS Analysis User's manual for more details.
      The following options with parameters have to be specified in the
      ABAQUS input file for the results (*.fil) file to be created and to
      contain stress invariant results:
          ...
          *FILE FORMAT, ASCII
          *EL FILE
          SINV
          ...
      NOTE: The results file (*.fil) must be placed in the same directory
      with the MATLAB source files in order to be processed.
      
  Input parameters
      #Rec# (string) is an one-row string containing the ASCII code of the
          ABAQUS results (*.fil) file. It is generated by the function
          Fil2str.m.
  
  Output parameters
      #out# ([#n# x 7]) is a double array containing the attributes of
          the record key 12 as follows:
          Column  1  –  Mises stress. 
          Column  2  –  Tresca stress. 
          Column  3  –  Hydrostatic pressure.
          Column  4  –  Currently not used.
          Column  5  –  Currently not used.
          Column  6  –  Currently not used.
          Column  7  –  Third stress invariant.
          where #n# is the number of elements multiplied by the number of
          integration points multiplied by the number of section points
          (for shell, beam, or layered solid elements) multiplied by the
          number of increments. If the results file does not contain the
          desired output, #out# will be an empty array
 
  _________________________________________________________________________
  Copyright (c) 2016
      George Papazafeiropoulos
      Captain, Infrastructure Engineer, Hellenic Air Force
      Civil Engineer, M.Sc., Ph.D. candidate, NTUA
      Email: gpapazafeiropoulos@yahoo.gr
      Website: http://users.ntua.gr/gpapazaf/