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Declaring Material Property as Function of x-coordinate

I am attempting to declare a material property (young's modulus) as a function of the x coordinates of the model. The function is an interpolation function titled E, so I inputted a table that corresponds to the x values and their respective E values. Then, in the material declarations, I input E(x) as the value for the young's modulus. When I build the model and check a 3D volume plot of the young's modulus values of the object, the values are also changing as a function of y and z coordinates. Additionally, the value on the model does not match the value in the interpolation table. For example, at x = .004, E should equal 312. But instead, at x = .004, E = about 327.

Any help?

9 Replies Last Post Nov 28, 2021, 7:44 p.m. EST

Posted: 3 weeks ago

For example, with the x-coordinate being moving to the right, I should not be seeing the change in young's modulus values in the z direction that is clearly seen in the image when I call young's modulus as E(X).

Posted: 3 weeks ago

Is your analysis geometrically nonlinear? In that case, it is important that you use a function of the material coordinate, X, and not the spatial coordinate, x.

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Henrik Sönnerlind
COMSOL

Posted: 2 weeks ago

Henrik, thanks for the response. I am using the material coordinate X. So, my Young's Modulus value is denoted E(X). However, I am still receiving the same response with young's modulus values changing in the y and z direction. Do you know of anything else that could be causing this?

Posted: 2 weeks ago

Is it possible for you to upload an example?

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Henrik Sönnerlind
COMSOL

Posted: 2 weeks ago
Updated: 2 weeks ago

In this simplified example, a sphere is created that should progress in young's modulus values starting at the center and moving to increased x values, as denoted by E(X). However, the young's modulus values are also changing with respect to the Y and Z coordinates.

Posted: 2 weeks ago

Hi Coleman,

I got an error when opening your example file. It seems like there is an interpolation data file that needs to be supplied for the model to work.

Best regards,

Magnus

Posted: 2 weeks ago

Magnus, My apologies you are correct. The txt file should be present now.

Posted: 2 weeks ago

Hi Coleman,

I don't really see the effect that you observe. Perhaps a volume plot is not the best view of the Young's modulus. In the attached model, I have added three Cut Line 3D datasets for plotting line graphs in the x, y, and z directions. Only the x-direction plot shows a variation. I have also added a Cut Point 3D dataset at the location (0.004, 0, 0), and evaluating `solid.E` at that point gives a value of about 312 MPa.

To run this model, you need to browse to and select the text file at the location where it is stored on your computer.

Best regards,

Magnus