Rk En Can you share your experimental mode shapes in Universal File format (.unv, .uff) and the finite element in an appropriate format?

As you have done your experiments with a uniaxial sensor, you may need to extract the responses from your FEA model for the equivalent DOF. This would possibly may involve a coordinate transformations if you do not have equivalent dofs and directions. You can do a MAC only for those measurement points & nodes which are equivalent. Hope that helps..

you need to ensure that the mode shapes being compared are in the same format. Here's a suggested approach:

Once you have both mode shapes in the same format (real-valued), you can calculate the MAC using the standard formula. The MAC formula involves comparing corresponding displacement values at each node between the two mode shapes.

Remember to normalize the mode shapes before applying the MAC formula. Normalization helps in removing any scaling effects and ensures a fair comparison between the mode shapes.

I hope this explanation helps you resolve the issue and accurately calculate the MAC between your experimental and FEM mode shapes. If you have any further questions or need additional assistance, please feel free to ask.

Hi

The Modal Assurance Criterion (MAC) is commonly used to compare and assess the similarity between mode shapes obtained from different sources, such as experimental measurements and finite element models. The MAC values range from 0 to 1, where 1 represents a perfect match between mode shapes.

In your case, it seems that you are dealing with mode shapes obtained from experimental measurements and FEM analysis, with different characteristics regarding the displacement components. To calculate the MAC correctly, you need to ensure that the mode shapes are appropriately normalized and that the dimensions and units are consistent.

Here are a few steps you can follow to calculate the MAC between the experimental and FEM mode shapes:

By following these steps, you should be able to calculate the MAC between the experimental and FEM mode shapes correctly. Remember to ensure consistency in units and dimensions while performing these calculations.

Nils Wagner Dear dr Wagner, I have done some meaurements on a real beam (concrete beam) and I used Artemis pro to obtain the mode shapes. the sensors that I have are 2 reference accelerometers that I import their time history responses in Artemis directly. I have not done any pre-processing to remove the noises. I used EMA (roving hammer). The mode shape that I have obtained is a little noisy. should I apply noise removal technics before importing the data in the Artemis?

I appreciate your time.