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PARAMETER

Parameters and functions

*PARAMETER
%param = expression, "description", rid, quantity

Parameter definition

Variable
Description
%param = expression
Parameter name and an expression defining its value
description
Optional parameter description
rid
Range ID for parameter manipulation in the GUI
quantity
Physical quantity
options: mass, coordinate, length, displacement, area, volume, time, stress, pressure, energy, power, acceleration, velocity, temperature, force, torque, moment, impulse, momentum, density, viscosity, srate, angledeg, anglerad, spindeg, spinrad, impint, cstiff, sstiff, tstiff, sdstiff, hcap, hcond

Description

The purpose of this command is to define parameters, that can be used inside expressions anywhere in the command file. Brackets are used to mark the beginning and end of an expression. Parameters should always be preceeded by the prefix %.

The range ID (rid) refers to either one of the commands PARAMETER_RANGE_CONTINUOUS, PARAMETER_RANGE_DISCRETE or PARAMETER_RANGE_BOOL.

Defining a physical quantity (quantity) is optional. It helps IMPETUS Solver determine how to convert parameters between different unit systems.

Supported quantities
Supported quantities

Example

Density

Definition of density parameters.

*PARAMETER %scale_factor = 2.0 %rho_steel = 7800.0 %rho_aluminum = 2700.0 *MAT_RIGID 1, [%scale_factor*%rho_steel] *MAT_RIGID 2, [%rho_aluminum]
Conversion between unit systems

A material command defined in SI-units is included in a model file working in MM/TON/S. The flow stress parameter $A=760 \mathrm{MPa}$ (defined in main.k) will replace the default value $A=640 \mathrm{MPa}$ (defined in material.k).

The resulting flow stress function in the material command is going to be:

$\displaystyle{\sigma_y = 760 + 450 \cdot \left( \varepsilon_{eff}^p \right)^n \; [MPa]}$

main.k:

# # --- MODEL IN MM/TON/S --- # *UNIT_SYSTEM MM/TON/S *PARAMETER %A = 760.0, "yield stress", 0, stress *INCLUDE material.k *END

material.k:

# # --- MATERIAL IN SI-UNITS --- # ~convert_from_SI *PARAMETER_DEFAULT %A = 640.0e6, "default yield stress", 0, stress %B = 450.0e6, "default hardening parameter", 0, stress %n = 0.3, "default hardening exponent" *MAT_METAL 1, 7800, 210.0e9, 0.3 1 *FUNCTION "flow stress" 1, 0, 0, 0, strain, stress %A + %B*epsp^%n ~end_convert *END