Material Properties and Libraries
You have used the functionality in Materials to access the properties of copper and titanium in the model of the busbar. This section will help you defining material properties and creating your own material library. Locate and open the file busbar.mph if you do not already have it on the COMSOL Desktop.
In Materials, you are also able to create your own materials and save them in your own material library. You can also add material properties to existing materials. In cases where you define properties that are functions of other variables, typically temperature, the plot functionality helps you in verifying the property functions in the range of interest.
First investigate how to add a property to an existing material. Assume that you want to add the bulk modulus to the copper properties, using a bulk modulus of 140 GPa.
Customizing Materials
In the Model Builder,
under Materials, click Copper.
In the Settings window,
locate the Materials Properties
section, which contains a list of all the definable properties. Expand
the Basic properties node,
right-click Bulk Modulus, and select Add to Material.
This will let you define the Bulk modulus for the copper in your model.
Locate the Material Contents
section. A Bulk modulus row is
now available in the table. The stop sign 
indicates the value is not yet defined. Define it by clicking
the Value column for the Bulk modulus row and entering 140e9.
By adding a material property, you have changed the Copper material. However, you cannot save this material in the Built-In library, since this is read-only. Instead, save it in your own library.
In the Model Builder,
right-click Copper and select Add Material to “User Defined Library”.
Right-click Materials
and select Open Material Browser.
In the Material Browser,
right-click User Defined Library
and select Rename Selected. Enter
My Materials in the Enter New Name dialog box.
