4.4.2 Hydrostatic Strain Energy

Incompressibility, linear and nonlinear compressibility models are available to describe the hydrostatic part of the strain energy function [§16.3.2]. DIANA chooses the model for incompressibility unless otherwise specified.

Incompressibility (default)    (syntax)

COMPRE

INCOMP specifies the incompressibility model.

BULK

k is the penalty constant $\kappa$ . ( $\kappa$ $\geq$ 0 ) [ $\kappa$ = 10⁶ ]

Linear compressibility    (syntax)

COMPRE

LINEAR specifies a linear compressibility relation [§16.3.2.1].

BULK

k is the compression modulus (or bulk modulus) $\kappa$ (16.40). ( $\kappa$ $\geq$ 0 ) [ $\kappa$ = 10⁶ ]

Nonlinear compressibility    (syntax)

COMPRE

specifies the compressibility model: SIMOTA for Simo-Taylor, or MURNAG for Murnaghan [§16.3.2.2].

BULK

k is the material constant $\kappa$ (16.41). ( $\kappa$ $\geq$ 0 ) [ $\kappa$ = 10⁶ ]

COMVAL

beta is the model constant $\beta$ in the Murnaghan model (not applied in the Simo-Taylor model). [$\beta$ = 9 ]

    (file.dat)

'MATERI'
    1  RUBBER   MOONEY
       RUBVAL   0.1  0.4
       COMPRE   LINEAR
       BULK     1000.