# Discussion Forum

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## Plotting the gap distance variable

I am trying to do something very simple, but it doesn't seem to be intuitive. I have a contact pair in the structural mechanics module and I want to plot the gap distance variable as a function of time. I know this is should be simple, but I am stuck!

Ryan

3 Replies Last Post Feb 22, 2013, 1:20 PM EST
Posted: 5 years ago
Hi

that should work, but do not forget that the gap distance is a field (hence depends on x,y,z and t) so for the plot either you take an average value or you measure from a "point" to get a time plot

Now I do not rem,ember the distance variable name in 3.5 any longer, check the doc and the equations, it's in there somewhere ;)

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Good luck
Ivar

Posted: 5 years ago
I plotted the gap distance variable (gap_cp21_smps, in my case) for contact pair 21 at point 108, which happens to be on the slave boundary for that pair. I attached a picture of the setup for clarity. The plot which COMSOL generated seems reasonable, however I am unsure of what the data physically represents. I thought that the gap distance variable was simply a distance that I could plot as a function of time. What does it mean to say "the gap distance variable at point 108"?

Also, how would I plot the average value of the gap distance variable?

Ryan

Posted: 5 years ago
Hi

if you check the doc, the gap distance of a "point" is the distance from that point along the surface normal to the interception of the other boundary, so if you want an average you need to average over a boundary area/distance, not that easy as you might not know where the contact is really over the contact region

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Good luck
Ivar

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