I have a model of a wind turbine blade made of abs polymer. I made experimental measurements and did ansys simulation to get the atural frequencies and mode shapes. The results in the first mode are close to each other but then for higher modes they become very deviated! I tried to modify mesh, material property, and even structure properties. Can you suggest anything else to try in order to get results closer to each other?
first mode error = 3%
second mode error = 20%!
third mode error = 8%
I would suggest to review the experimental technique, where is the fixation applied and try to do the same in the FE model. The boundary conditions have a very important impact. Second you say that the you modified the mesh, what is the criteria that you are using? generally the typically accepted grid resolution is (6 point per maximum wavelength). If you know the frequencies that you targeting, and the material you can determine the wavelength, and then make sure there at least 6 points per wavelength are achieved. Take the length of the element as the maximum of length and height if the element is square, if the element is triangle take the maximum height of the element.
Although I think from the deviation that you are having, that it had to do with the boundary condition, and probably if you plot the mode shape, it will be something that you have missed in the boundary conditions near the highest deformation points.
Have you checked the total mass of the model? This should be exactly the same as the experiment.
Yes Martin , The mass is very close to each other although I have changed some dimensions in the FEM model to get the mass close to real part !
I think your observations stem from your last post. You mentioned "I have changed some dimensions in the FEM model". By this, you have changed blade stiffness and of course you wouldn't get experimental results.
What type of wind turbine are you trying? Is it VAWT? because I'm trying to simulate the vertical axis wind turbine blade using CFX. Are you using CFX or FLUENT?
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