MEXICO Toolbox

This toolbox automatically correlates the modal properties of the structure to validate the numerical model before the simulation

[Model-Experiment Interactive Correlation Toolbox]

The MEXICO Toolbox is a programme capable of modal model correlation for validation. It implements a series of methods (MAC, COMAC, modal complexity plots, natural frequency plot and diagram, additionally invented Mode Complexity Indexes and the Modal Validity Score metric) to provide a user with information about the accuracy of the theoretical model based on comparing modal properties with the experimental results. Moreover, the toolbox has a feature of extracting the data for particular nodes from FEA based on the geometrical correlation. The toolbox requires:

• results of modal testing (mode shapes and natural frequencies) in the ‘.mat’ format

• coordinates of points excited in the modal testing

• ‘.inp’ file containing the FEA meshing data

• ‘.dat’ file with printed displacements for each DOF

To use the toolbox, follow the below steps:

1. Copy the results from modal testing to the toolbox folder. The results should contain ‘ms’ and ‘fn’ files with mode shapes and natural frequencies. Name the results file as EXP_MP_RESULTS

2. Open the INSERT_GEOMETRY.m file in MATLAB and put the coordinates of points extracted in the modal testing. Complete the following lines with node labels and their connectivity. After inserting those data, run the script to create the EXP_GEOMETRY.mat file

3. Open MEXICO.mlx

4. Substitute lines 5 and 6 with paths for to the ‘.inp’ and ‘.dat’ files from the FEA

5. (OPTIONAL) If your FE model meshing type is different than C3D10, open the mesh.m function and substitute matrix ‘face’ with element connection numbering suitable for the mesh type used

6. Run the MEXICO script (line 1)

7. In the Geometric Correlation Window align the experimental geometry with the FE meshing by using the manipulation console in the bottom right-hand side

8. Once the nodes are matched (you can check that with the node showing buttons), push the Get nodes button. This will print the number of 20 nodes to the workspace, which will be extracted from the ‘.dat’ file

9. Push the Correlate button. After a few seconds, a Model Validity Score window will pop up telling you the estimated quality of the model. After clicking See Figures, you can see 11 figures correlating numerical and experimental natural frequencies, and mode shapes and presenting the complexity of experimental mode shapes

YouTube tutorial available here -> https://youtu.be/A2oro7oJQSA