# Intersecting surface area

I’m looking for a way to calculate the surface area where two components overlap along one plane. I’m often dealing with very odd geometry, so it’s very time-consuming to get an accurate number. Just curious if anyone knows of an extension that may be able to help with this, or know of an easier method. Thanks in advance!

Can you share a couple of components set up to show what exactly you are trying to accomplish?

1 Like

I’m not able to share exact replica of the components…not very accurate sketch of the part, but this shows the basic concept. The dark gray area is foam that would be used for a shipping container, and I need to determine the surface area of contact with the part just along the bottom surface so I can use cushion curves of the foam material to determine g-shock that could be transferred to the part if the container were dropped in transit.
Surface Area Example.skp (815.9 KB)

Would something like this be the info you are trying to get? I just selected the faces in the bottom of the recess here and Entity Info shows the area.

Or in this case I moved the next layer of foam down and intersected the top face of this foam layer with that one to get the outline of the opening.

Do these recesses accurately reflect the way the foam is cut? Or is it more closely shaped to the object being shipped?

This strikes me as a much more difficult problem than just calculating areas. The “spool” part is rounded. So, as it sinks into the flat surfaces of the foam, it compresses the foam more along the centerline than at the edges. The supporting force will vary with compression. You could get an approximate answer by moving the spool down some amount, intersecting with the foam, and getting the area of each face of the intersection. Then multiply that area by a support force based on the distance the foam was compressed by that face.

Thanks DaveR - I’m fairly new to SketchUp, and didn’t know that info existed there. Pretty close to what I’m looking for. It gave me an idea - I think I could move the part 1/4" down to intersect with the foam, then rt click the foam face and intersect with model to outline where it’ll contact (with a minimal fudge factor based on the 1/4"). Thanks for the help!

Happy that helps.

FWIW, if the foam was going to be more form fitting you could use Trim from the Solid Tools and use the object to trim the recess. Then select the surfaces in the foam to get the area.

Exactly - it is much more complicated Tried to simplify as much as I could to at least get a starting point, then start digging into the nitty-gritty with a spreadsheet and formulas. I’ll have to drop each part down slightly (distance determined based on density of the foam compared to the weight of the part), but it’ll be close enough for gov’t work. Thanks for the insight!

Hoooold up - is that a tool built into sketchup, or is it an extension? Either way - I need it. Just searched for the extension, and didn’t find it on Extension Library or SketchUcation.

Majority of stuff we work with isn’t molded foam since we do very low volumes, so we end up CNC routing 2" layers to develop the profile. Would still be a very useful tool…because then I could get the full mold like you did, then slice into layers.

The Solid Tools are native in SU2020 Pro. I use Eneroth Solid Tools which is available in the Extension Warehouse instead because I work exclusively with components and the native solid tools convert components to groups. With either tool both the object you are shipping and the “foam” need to be considered solids. Entity Info will show you that.

I was experimenting with a thing I made a long time ago and created a nest in multiple layers of “foam”. I wonder if there’s a way to do something with the average slope of the recess to make your calculations more accurate.

Yeah, that’d be a tough calculation for sure, since as the foam cutouts become more vertical they’re offering less direct support of the part (at least from a shock standpoint if it’s dropped flat on the base).

1 Like