Accelerometer Selection

 

Sometimes it is desirable for the test-planner to preselect some accelerometer locations. These locations may not necessarily improve the Pseudo-orthogonality or Self-MAC and would therefore not be selected by the GA, however they may improve mode shape visualization for a test-display model or may be desirable for other reasons. Similarly, sometimes the candidate set TAM includes DOF that the user would like to exclude from consideration of the final accelerometer selection set.

 

Clicking either the Manually Select Accels or Manually Exclude Accels buttons on the GA Options form bring up the Select Accel Locations form, as shown in Figure 16. The Select Accel Locations form allows the user to manually select locations that will be included or excluded from all accelerometer sets, including all Seed TAMs. Individual locations can be selected in the form, or they can be loaded from an ASCII file. Two file types are supported. A Nastran bulk file containing ASET cards can be used to define the preselected/excluded DOF or a 2-column generic text file where the first column is the grid ID and the second column is the DOF (numeric values for X, Y, Z directions). The generic text file can use any standard delimiter (comma, semicolon, tab, etc.) and cannot contain any non-numeric characters. If the selected file contains grids or DOF that are not in the candidate set they will be ignored. If the Pick Triax Accels box is checked, then only the grid IDs of the ASET cards or the first column of data from the generic file is used to select the grid IDs.

 

Note that the number of DOF that are manually selected reduces the number of accelerometers selected by the Genetic Algorithm. If more than 30% of the Total # Accels are manually selected a warning is issued upon clicking the Solve button.

 

Figure 16. Manual select an exclude accelerometer locations form.