Irreversible Transformation

Three models are available to define the material transformation. Select the — (default), , or . The first two models use integral forms over time to express the fraction of transformation θit as a function of temperature, while you can set it manually with the third option.

For , select the type of analysis — (default) or , depending on the expected temperature variations. See the Parameters section for the additional settings specific to each type of analysis.

For , define the parameters used in the Arrhenius equation to calculate the degree of transformation (see Arrhenius Kinetics for more details):

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A in the Arrhenius equation. Default is taken . For enter a value or an expression.

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ΔE in the Arrhenius equation. Default is taken . For enter a value or an expression.

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n of the (1−α) factor to define a polynomial Arrhenius kinetics equation.

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L to define the enthalpy variation associated with the transformation. The following heat source is added to the right-hand side of Equation 6-17 in Solid node:

A user defined value can be set for the initial irreversible transformation indicator in the Initial Values section.

Enter values or expressions for the L and the θit to define the heat source associated with the transformation as:

Specific thermodynamics properties before and after complete transformation may be defined by selecting the check box.

Choose a ,which can point to any material in the model. The default uses the . The properties before transformation are the ones specified in the and sections of the parent Solid node. The effective material properties are dynamically updated with the transformation evolution.

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Tit, h to define the (high) temperature that the solid needs to reach to start getting transformed.

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tit, h to define the time needed for the complete transformation to happen while the temperature is above Tit, h.

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Lit, h to define the enthalpy variation associated with transformation due to overheating. The following heat source is added to the right-hand side of Equation 6-17 in Solid node:

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Tit, c to define the (low) temperature that the solid needs to reach to start getting transformed.

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tit, c to define the time needed for the complete transformation to happen while the temperature is below Tit, c.

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Lit, c to define the enthalpy variation associated with transformation due to overcooling. The following heat source is added to the right-hand side of Equation 6-17 in Solid node:

A user defined value can be set for the initial irreversible transformation indicator in the Initial Values section.

This section is available when the check box is selected.

Select a kd — (default) or , to be used for transformed solid. For choose , , , or based on the characteristics of the thermal conductivity and enter another value or expression in the field or matrix.

This section is available when the check box is selected.

Select a ρd and Cp, d — (default) or , to be used for transformed solid. The heat capacity describes the amount of heat energy required to produce a unit temperature change in a unit mass.

This section is available when the is set to or . Set a value or expression for the , αinit, to be used as an initial condition for any of the time integral analyses.