Modal Reduced Order Model
The Model Reduction and Modal Reduced Order Model study steps have the property that they can assemble the modal matrices and make them available for output. In the Model Reduction node, the Store reduced matrices check box must be selected.
After solving the model, right-click the Derived Values node (under Results) and select System Matrix. In the output section, select the Matrix to display and the Format. Using the Matrix settings it is possible to access the stiffness, damping, and mass matrices of the system, for example.
In the COMSOL Multiphysics Reference Manual: