To Assign a Material
1. Click > 
Material Assignment. The Material Assignment dialog box opens.
Material Assignment. The Material Assignment dialog box opens.2. Enter a name for the material assignment or use the default name.
3. From the References list select Part or Volumes if you are in part mode. In assembly mode, select Components or Volumes for material assignment.
4. Select model references for material assignment.
5. In the Properties area, select the existing materials of the model from the Material list. If you do not see the material that you want, click More to select materials from the library.
6. Select None as the material orientation from the Material Orientation list or click More to specify the material orientation using the Material Orientations dialog box.
If you are working with an assembly, you can select a subassembly or the entire assembly on the Model Tree or on the model. In this case, Creo Simulate assigns the material to all parts in the selected assembly or subassembly.