In Phase2, the properties of a material can be modified at different stages of a multi-stage model, by using the Stage Material Properties option in the Define Material Properties dialog. This allows you to simulate, for example:
an increase or decrease in material stiffness
an increase or decrease in material strength
as staging progresses. The material properties can be increased or decreased by user-defined factors at different stages, as described below.
To stage material properties:
In the Define Material Properties dialog, select the Stage Properties checkbox at the bottom of the dialog.
The Define Factors button will now be enabled. Select this button, and the Stage Material Properties dialog will appear.
In the Stage Material Properties dialog, select the Add Stage button, until the number of rows in the dialog, is equal to the number of stages at which you need to modify the material properties. For example:
if you need to modify material properties at 3 different stages, then select Add Stage TWICE, so that a total of 3 rows appears in the dialog.
In each row, enter the Stage number at which the properties are to be modified.
In each row, enter the required Factor(s) which will be used to modify the indicated material parameter(s). NOTE:
the Factors are multiplied by the parameter values in the Define Material Properties dialog, in order to obtain the actual value to be used for a parameter, at a given stage of the analysis
for example: if you want to increase Young’s Modulus by 20%, enter a Factor of 1.2 for Young’s Modulus, at the desired stage(s)
leave the Factor = 1 for any parameter which does not change value
as you enter factors in the dialog, a summary of the material properties at each stage will be displayed in the area at the right of the dialog
Reset Yield - allows you to reset the yield status of failed elements, see below for details.
It is important to note that you only need to define the stage and factor information, for the stages at which you want to modify properties. You DO NOT need to define this information at stages where the properties do not change.
If you accidentally add too many rows with the Add Stage button, click the mouse in a row and select the Delete Stage button, to delete the row.
When you are finished entering all stage numbers and factors, select OK in the Stage Material Properties dialog. Select OK in the Define Material Properties dialog when you are finished defining all materials.
When the analysis is run, Phase2 will use the factors in the Stage Material Properties dialog, to determine the material properties to be used at each stage of the analysis, for a given material.
Reset Yield
When a solid element yields, a yield flag is assigned to the element and is kept for all subsequent stages. This is the default setting (i.e. Reset Yield = No).
If you wish to reset the yield flag for failed elements in a material, you can choose Reset Yield = Yes. In this case, the material strength of elements that yielded previously will be reset to peak strength. This can be used, for example, if a material has been strengthened by grouting, and you wish to change the material strength parameters, and reset the yield flag of previously failed elements.
The Reset Yield option is only available if the Material Type = Plastic in the Define Material Properties dialog.
Staged Properties Tutorials
A typical use of staged material properties, is the staged reduction of material modulus, to simulate the 3-dimensional advance of a tunnel face. This is discussed in the following tutorials, developer's tips and FAQs:
Material Softening (Developer's Tip)
Phase2 Theory FAQs (see FAQ #10 and #11)