If you specified the optional Fiber Volume Fraction File in the Injection Molding Data system, you can import and map the fiber volume fraction field onto the structural mesh by following this procedure in Mechanical:
Open the Materials folder as well as the Imported Material Fields object.
Either select the Imported Material Field child object or insert a new one if you already imported other material fields.
Scope the object to the geometry of interest.
As necessary, review and modify the remaining default settings of the properties in the Details View.
In the Data View, make sure to select the FiberVolumeFraction identifier.
Right-click the Imported Material Field object and select the Import Material Field option from the context menu. This action maps the fiber volume fraction field to the elements of your model.