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Hi Hans,

You can first find the coordinates of the max/min values and then compute the distance. One approach to doing this is plotting the displacement dependent variable (instead of magnitude) and then adding a "Marker" to the plot. This will display the min and max values along with the coordinates. Another option is to use the maximum and minimum nonlocal component couplings with a second arguement for coordinate as decribed here: https://doc.comsol.com/5.5/doc/com.comsol.help.comsol/comsol_ref_definitions.12.081.html . When computing the distance from the max/min values, you do have to be a bit careful and may need to account for an integer distance in the calculation, especially for higher modes since it is possible the global maximum and minimum values are not right next to eachother.

Best, -Mark

Hi Hans,

You can first find the coordinates of the max/min values and then compute the distance. One approach to doing this is plotting the displacement dependent variable (instead of magnitude) and then adding a "Marker" to the plot. This will display the min and max values along with the coordinates. Another option is to use the maximum and minimum nonlocal component couplings with a second arguement for coordinate as decribed here: https://doc.comsol.com/5.5/doc/com.comsol.help.comsol/comsol_ref_definitions.12.081.html . When computing the distance from the max/min values, you do have to be a bit careful and may need to account for an integer distance in the calculation, especially for higher modes since it is possible the global maximum and minimum values are not right next to eachother.

Best, -Mark

Hi Mark,

Thanks for the reply!

I am a little confused on how I can plot the displacement dependent variable and add a marker.

Could you point me in the right direction? Thank you!

Consider the vibrating string example here: https://www.comsol.com/model/vibrating-string-8535 . The default plot for Mode Shape plots wire.disp (displacment magnitude). If you plot "v", this is the dependent variable for displacement in the y direction. Then right click Line 1-> Marker to add the max/min marker. The screenshot shows the min and max coordinates in the table from the marker. Subtracting the x values should give you the distance for this case.

Consider the vibrating string example here: https://www.comsol.com/model/vibrating-string-8535 . The default plot for Mode Shape plots wire.disp (displacment magnitude). If you plot "v", this is the dependent variable for displacement in the y direction. Then right click Line 1-> Marker to add the max/min marker. The screenshot shows the min and max coordinates in the table from the marker. Subtracting the x values should give you the distance for this case.

Mark, I really appreciate the very detailed reply. I was able to follow along and replicate your results with the vibrating string.

When I try it on my 3D asymmetric model, my min and max values does not yield the result I am looking for (which is the distance between the nodes of each bending mode).

Is it possible to add specific points on the geometry and calculate the distance between said points?

edit: I understand you mentioned this in your first reply---"may need to account for an integer distance in the calculation, especially for higher modes since it is possible the global maximum and minimum values are not right next to eachother."

However since this is an asymmetric (nonprismatic) beam, there is a chance that the nodes are not evenly spaced. This is why I wish there is a way to put markers and get the distance between two consecutive nodes, or the distance between nodes (like a ruler/distance measure tool)

For completeness, I will add here that using the Graph Marker with a 1D plot group->line graph (select edge) can be used to plot local max and min values when the scope is changed to Local. For the vibrating string example, a plot of this is attached.