Chair notes

Custom rocking chair One of King Tutankhamun’s chairs IKEA’s chair no xx

The Dutch King William is ready for the annual Throne Speech. Notice the difference between his throne and the chair of the Queen.

Large scale structural ‘chair’ holding up the cables of an early suspension bridge

1.  a physical structure, composed of real material, subject to real influences, such as gravity loads, temperature, humidity, swelling-shrinking, twisting, decay.

2.  the chair gives clues about the nature of the human body: weight, moveable joints at the knees and hips.

3.  the chair indicates the social class of the owner

4.  the chair consists of elements that are connected in a very specific way thus forming the structure.

5.  The structure is stable under varying conditions. A person sitting on it in a rest position loads the four legs of the chair relatively evenly and symmetrically; but if the person leans back on the two hind legs a much more complicated, unstable, asymmetric, load pattern results, wherein the two rear legs take all the load plus a bending moment from the seat and the bottom cross-bar connection.

6.  A rocking is stable within the ‘rocking’ limits.

7.  The chairs shown above are made of wood- a natural polymer that consists of long, bundled molecular strands or chains.

8.  The linear, non-isotropic nature of wood is well-understood by the designer of this chair: the legs, braces and seat all use the material’s linearity to advantage.

9.  The front legs, which receive mainly centrally located compressive loads are square, while the back loads, which are mixed compressive-bending loads are rectangular to be able to resist these combined loads.

10.  The chair elements are sized to be able to support the weight of a human, but not much more, so that the chair as light as possible, allowing an individual to easily pick up the chair and move it. The chair weighs 6 pounds and can, according to the fact sheet support 220 pounds, thus the weight/load ratio is 1/37

Chair testing:

folding chair ‘car’ test

https://www.youtube.com/watch?v=NwgfqO410ts

office chair testing

https://www.youtube.com/watch?v=5HCZO7FunjY

Herman Miller fatigue testing

https://www.youtube.com/watch?v=iyIRQGENpA8

downhill test:

https://www.youtube.com/watch?v=W-hs7uLd4r8

racking test:

metal chair:

http://www.fmmcenter.ncsu.edu/testlab/img/racktest3.mov

wood chair:

http://www.fmmcenter.ncsu.edu/testlab/img/racktest2.mov

wood highrises:

https://www.youtube.com/watch?v=O4XLRLY29iw