4.1.3 Ambient Influence

DIANA can apply standard ambient influence on isotropic elasticity. General influence on Young's modulus can be specified via a user-supplied subroutine.

4.1.3.1 Isotropic Elasticity

When evaluating ambient influence on isotropic elasticity properties, DIANA will consider the incremental relationship

$$\boldsymbol\sigma \boldsymbol\varepsilon \boldsymbol\varepsilon$$ (4.2)

where D is the elastic stress matrix of the material. This relationship must not be used in case of solidifying materials (e.g. hardening material) as it is thermodynamically incorrect. Bazant [4] suggested in that case to use

$$\boldsymbol\sigma \boldsymbol\varepsilon$$ (4.3)

In order to consider the incremental relationship (4.3) you must apply a viscoelastic model using the Power Law creep function [§7.1]. Using such a viscoelastic model, creep deformation can easily be set to zero by defining $\alpha$ = 0 in the POWER input data item.

    (syntax)

TEM___

for temperature influence: te1 to ten (n $\leq$ 30 )are temperatures T . The temperature-time dependency must be specified via input table 'TEMPER' [§1.2.1].

CON___

for concentration influence: co1 to con are concentrations C . The concentration-time dependency must be specified via input table 'CONCEN' [§1.2.2].

MAT___

for maturity influence: mv1 to mvn are maturity variables M . The maturity-time dependency must be specified via input table 'MATURI' [§1.2.3].

___YOU

influence on Young's modulus E , values e1 to en are the E 's for the corresponding ambient values respectively.

___POI

influence on Poisson's ratio $\nu$ , values nu1 to nun are the $\nu$ 's for the corresponding ambient values respectively.

___ALP

influence on thermal expansion coefficient $\alpha$ , values al1 to aln are the $\alpha$ 's for the corresponding ambient values respectively.

___GAM

influence on concentration expansion coefficient $\gamma$ , values ga1 to gan are the $\gamma$ 's for the corresponding ambient values respectively.

    (file.dat)

'MATERI'
  1   YOUNG   210000.
      POISON  0.3
      TEMYOU    0.0  210000.
              200.0  210000.
              500.0  150000.
      TEMALP    0.0  1.2E-6
              600.0  1.0E-6

In this example the constant values for Young's modulus YOUNG and Poisson's ratio POISON are input for the preliminary linear analysis.

4.1.3.2 User-supplied

DIANA offers the user-supplied subroutine mechanism for general specification of the ambient influence on the Young's modulus and Poisson's ratio, for instance with a mathematical function. The ambient influence can be any function of temperature, concentration, maturity and time.

    (syntax)

USRYOU

specifies that the ambient influence on Young's modulus is determined via a user-supplied subroutine [§11.1.1].

USRPOI

specifies that the ambient influence on Poisson's ratio is determined via a user-supplied subroutine [§11.1.2].

DIANA passes the keyword usrkey to the first argument of the appropriate subroutine.