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joshuamunson

As long as the center of gravity is within the base of the chair it will hold you upright. A chair like the one posted holds the materials in tension and compression in order to not collapse. Since the center of gravity of the person in the chair is within the square base it will not tip over.


thecookiesayshi

Thank you for your response. What do you mean by 'matials'?


joshuamunson

Sorry I fixed it. I meant materials, in this case the wood.


thecookiesayshi

Gotcha. Thanks.


ghostwriter85

The frame resists bending. That's all there really is to it Ignore the cross members, and just consider the two "C" shaped members to either side. If we can make our C's stiff and strong enough, we put force on top of them. The outer "C" frame bends as we sit in it (slightly), this bending is what transfers the force from our butt to the ground. Now provided our butt is in the area between the "C" frames, the chair can't tip over. \[edit - much of the appeal of chairs like these is that they bend oddly enough, the slight bending of the frame makes the chair feel much more natural than a four leg chair that supports itself in compression which isn't as forgiving to our butts\] The parts that go sideways are mostly just there for stability. Hopefully that helps (maybe not), but it's hard to answer your question in a satisfying way (to me anyway) without bombarding you with a bunch of ideas that probably won't be helpful. If you really want your mind blown consider this chair [https://uploads-ssl.webflow.com/5e31fdccf28730054fa1631c/5f7b3c5294883853f0c1b212\_floating%20chair.jpeg](https://uploads-ssl.webflow.com/5e31fdccf28730054fa1631c/5f7b3c5294883853f0c1b212_floating%20chair.jpeg)


thecookiesayshi

Thank you for your detailed response. How would one go about understanding how much of the "heavy lifting" is done by either of the bends/corners of each `C` vs the longer vertical portions? Where is most of the force being applied when one sits in it? I think I'm asking the question I mean to be asking... :) p.s. that chair is nuts. It looks like most of the heavy lifting in that chair is done by the short strand in the middle that falls from the base?


ghostwriter85

... a degree in mech eng, civil eng, or physics with an emphasis on structural analysis In short the load always has to be transferred from the point it is applied to the foundation. It will tend to take the most direct path. So in our chair's case, the load starts in the seat. The seat pulls down on the C at the attachment points. The C part bends and compresses. This bending and compressing action sends the load down the vertical part into the foundation. In the foundation, the bending is relaxed into the ground. Hopefully that makes sense. \[edit - insofar as where the actual point of max loading is, it's probably in the bend right before the ground but please don't quote me on that\] As for your p.s. - yes that's correct. The tension wires can't take load. They pull down on the top to prevent the chair from twisting or tilting. The strand in the middle transfers all the load to the base. In wire supports, it's not uncommon for a central wire to take the load and have wires pulling down (against the central wire) to keep the object stable. These "floating" objects just look very weird because the relative position of the various wires is reversed in a way that looks like it shouldn't be stable but is.


thecookiesayshi

Crystal clear on both. Thank you very much for your time!


d0meson

The two legs are like springs -- they exert a force when they're bent by someone sitting on them, and that force is what keeps you off the ground.


thecookiesayshi

Just that they're really, really tight springs? At the corners of the chair, specifically?


d0meson

Well, it's more like the whole piece of wood is a tight spring. Think about a bow and arrow -- when you pull back the arrow, the wood of the bow bends and pulls on the string in the opposite direction. The two legs of the chair are like two bows in that respect, just without a string joining their ends.


thecookiesayshi

I understand. Thank you!