COMSOL Implementation
The Component Mode Synthesis (CMS) technique is currently implemented in the Solid Mechanics, Shell, and Multibody Dynamics interfaces. You use the Reduced Flexible Components node in either of these interfaces to control the generation and use of such reduced components.
Reduced components are connected to each other and to nonreduced parts of the model through Attachment features. It means that all physics features that can access an attachment can be used to connect the reduced components. The most common option is to use joints, but there are other alternatives, such as Spring–Damper, or bearing foundations in the rotordynamics interfaces.
The global model can consist of either a set of reduced components, or a mix of ordinary FE discretized domains and reduced components. The reduced components can be used as linear parts in an otherwise nonlinear model.
A requirement to be able to create a valid reduced component is that its underlying physics is linear with regards to material models, the strain formulation, and other possible contributions such as springs and loads
COMSOL Multiphysics always forces a geometrically linear formulation on selections that intersect that of a Reduced Flexible Components node.
When using a reduced component in the global model, the connection to nonreduced parts must be such that the deformation of the reduced component is limited to small rotations and small strains.
You can compute all type of results and visualize reduced components just as if they are ordinary domains in your model. One important property of the reduced component is that only the results for the reduced set of degrees of freedom are stored. It means that for time-dependent studies with many time steps, the file sizes can be reduced by orders of magnitude.