5.1.7 Fraction Model

This section describes the input syntax of the fraction model for generic elements. The model may be used to model kinematic hardening for plasticity and metal creep analyses. It splits the material into a number of fractions, each of them having its own plasticity and creep parameters. See §17.1.9 for background theory.

    (syntax)

FRACTI

specifies the fraction model: values phi1 to phin are the volume parts $\phi_{{i}}^{}$ of the fraction. ( 0 $\leq$ $\phi_{{i}}^{}$ $\leq$ 1 )The sum of the volume parts must be equal to 1. The number of specified phi values determines the number of fractions n in the model. (n $\leq$ 10 )

frnr

is the fraction number. Don't forget the leading comma.

Input data for plasticity or creep or both must be specified for each fraction number [Ch.5] [§8.1].

Metal plasticity    (file.dat)

  1  YOUNG   210000.
     POISON  0.3
     FRACTI  0.7  0.3
  ,1 YIELD   VMISES
     YLDVAL  200.
     HARDEN  WORK
     HARDIA  200. 0.  300. 0.001  400. 0.003  400. 1.
  ,2 YIELD   VMISES
     YLDVAL  500.

This is an example input of the fraction model for metal plasticity. It contains two fractions with volume parts $\phi_{{1}}^{}$ = 0.7 and $\phi_{{2}}^{}$ = 0.3 . The first fraction is for Von Mises plasticity with a hardening diagram of three branches (four points). The second fraction is for Von Mises plasticity only.