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Old 02-26-2007, 08:19 AM   #707
HL1978
Dojo: Aunkai
Location: Fairfax, VA
Join Date: Aug 2006
Posts: 429
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Re: Baseline skillset

Quote:
Erick Mead wrote: View Post
I learned three classes of engineering structural connections:

1) a roller joint which is free to move laterally without friction and to pivot freely at the point of support,

2) a hinge joint which can pivot freely about the point of support but not move laterally

3) a pinned or fixed joint that is not free to move laterally or to pivot.

Trusses or spaceframes must have pinned or fixed joints.

Stable arches can have pinned joints or up to three hinges, but no rollers.

A beam can have any combination of the three. (Continuous beams can have more that two points of support.)

There is a fourth, of a sort, but plastic connections are very non-linear.
Just to add a bit and say that when talking about structure, some of the assumptions are a bit flawed.

What if the fasteners for the various hinges/joints are loose?

Wouldn't that change one type of joint into another?

Would tightness/loosness in the joint change which type of deformation (plastic etc)occurs at varying loads?

What if they are tight? What if some of them are loose and others are tight? That is to say they aren't uniform, or can selectively be chosen which are loose and which are tight?

Think about that for a bit and the grounding sensation that people are talking about might make a bit more sense if you want to talk about it from mechanics/statics. Its like if you played with an erector set and only tightend some of the fasteners, how would that effect how the erector set was loaded.

Last edited by HL1978 : 02-26-2007 at 08:27 AM.
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