9.1. Predefined Field Variables

The following predefined field variables (defined via TBFIELD) are supported by the material models indicated:

Table 9.1: Predefined Field Variables and Supported Material Data Tables

Field Variable Description Material Model (TB,Lab) Support
TEMPTemperature

All material models via TBTEMP.

If using the material models listed in this table, you can also define temperature via TBFIELD,TEMP.

FREQFrequency
CYCLEHealing cycle
NPRESNormal pressure
SLDISliding distance
SLRVSliding velocity
TIMESolution time
UX, UY, UZ[b]Displacements in the global/local X, Y, or Z coordinate system, respectively
XCOR, YCOR, ZCORGlobal or local coordinate system locations
UF01 - UF09 User-defined
PPREPore-pressure degree of freedom
PLSREquivalent plastic strain rate

  • Bilinear isotropic hardening (TB,PLASTIC,,,,BISO)

  • Multilinear isotropic hardening (TB,PLASTIC,,,,MISO)

  • Nonlinear isotropic hardening (TB,NLISO,,,,VOCE / POWER)

SRATStress ratioSMART-based fatigue crack-growth (TB,CGCR,,,,PARIS / TFDK).

[a] Coupled-pore-pressure-thermal elements (CPTnnn) not supported.

[b] For elements with displacement degrees of freedom only.


The reference coordinate systems for location (XCOR, YCOR, ZCOR) and displacement (UX,UY,UZ) can be modified from global (default) to any user-defined Cartesian coordinate system specified via TBEO. Coordinate transformation includes both translation and rotation; if you require only rotation for displacement, define a coordinate system that only has rotation.

In a linear analysis, when a field variable changes during solution, the full Newton-Raphson option (NROPT,FULL) is required to obtain the correct behavior.

 

9.1.1. Defining Friction

The TEMP value corresponds to the average temperature on the contact surface for contact elements CONTA172, CONTA174, CONTA175, and CONTA177. For contact element CONTA178, the TEMP value corresponds to the average temperature of the nodes.

The TIME value corresponds to the analysis time specified via TIME.

The algebraic sliding distance SLDA is the total sliding distance (the algebraic sum) as reported in the element output definitions table for the contact elements (for example, TASS and TASR output items for CONTA174).

The absolute sliding distance SLDI is the total accumulated sliding distance (the absolute sum) as reported in the element output definitions table for the contact elements (for example, AASS and AASR output items for CONTA174).

When used with TB,FRIC, field variables defined via TBFIELD are available only for isotropic friction (TBOPT = ISO) and orthotropic friction (TBOPT = ORTHO or EORTHO); they are not available for user-defined friction (TBOPT = USER).

For more information about using TBFIELD with TB,FRIC, see Contact Friction in the Material Reference.

 

9.1.2. Defining Young’s Modulus as a Function of Global X,Y

! Young's Modulus as a Function of Global X,Y
TB,ELASTIC,1
 
TBFIELD,XCOR,0.0
TBFIELD,YCOR,1.0
TBDATA,1,1e6,0.3
TBFIELD,YCOR,5.0
TBDATA,1,1e7,0.3
 
TBFIELD,XCOR,1.0
TBFIELD,YCOR,1.0
TBDATA,1,1.1e6,0.3
TBFIELD,YCOR,5.0
TBDATA,1,1.1e7,0.3