Tools | Measurement Expansion

Expands the measurements in a Data Block using a set of shapes.

This command uses the same equation for linearly relating one set of shapes to another as the Tools | Shape Expansion command in a Shape Table, and the Modes | Modal Decomposition command in a Data Block

This command is useful for;

  1. Expanding a Data Block with a few M#s using shapes with more M#s in them

  2. Expanding a Data Block of time or frequency measurements using FEA shapes

The Measurement Expansion algorithm performs a least-squared-error curve fit of the shapes to each sample of the Data Block data at the common DOFs between the shapes and the Data Block. A participation matrix of the shapes is calculated fro each sample of Data Block data  Then the participation matrix is multiplied by the shapes to obtain the expanded values of the measurements at each sample.

Only mode shapes are used for Measurement Expansion.
Modal Frequency & Damping are not used.

The shapes must meet the following conditions,

  1. The shapes are valid for the structure regardless of boundary conditions.

  2. The shapes are linearly independent of one another for the common DOFs between the shapes and the Data Block

If these two conditions are met, the shapes provide a valid expanded set of measurements for all of the unmeasured DOFs of the structure represented by the DOFs in the shapes.

  1. Execute this command in the Data Block containing the measurements to be expanded

  2. A file dialog box will open from which the Shape Table containing shapes to be used for measurement expansion can be selected

  3. After the calculation is completed, another file dialog box will open allowing you to save the Data Block with the expanded measurements in it

Measurement Expansion can be controlled by selecting shapes and/or M#s in either the Data Block or Shape Table before executing this command.