- #1
rmrramani
- 17
- 0
can u explain what is kinematic indeterminancy?
What is kinematic indeterminancy?
- Thread starter rmrramani
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- Kinematic
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Discussion Overview
The discussion revolves around the concept of kinematic indeterminacy, particularly in the context of structural engineering. Participants explore its relationship to static indeterminacy and provide examples to illustrate the differences between statically determinate, statically indeterminate, and kinematically indeterminate structures.
Discussion Character
- Technical explanation
- Conceptual clarification
- Debate/contested
Main Points Raised
- One participant requests an explanation of kinematic indeterminacy.
- Another participant expresses unfamiliarity with the term and seeks context.
- A participant relates kinematic indeterminacy to static indeterminacy, referencing a source on structural and stress analysis.
- A detailed explanation is provided, distinguishing between statically determinate, statically indeterminate, and kinematically indeterminate structures, using sketches to illustrate the concepts.
- The explanation emphasizes that kinematically indeterminate structures can change shape under load, making it impossible to determine member forces solely from equilibrium equations.
- A later reply expresses appreciation for the clarity and precision of the explanation provided.
Areas of Agreement / Disagreement
Participants generally agree on the definitions and distinctions between the types of indeterminacy discussed, although there is some uncertainty regarding the term "kinematic indeterminacy" itself, as not all participants are familiar with it.
Contextual Notes
The discussion highlights the need for clarity in terminology, as some participants are not familiar with kinematic indeterminacy, which may affect their understanding of the concepts being discussed.
- #2
Cyrus
- 3,246
- 17
I have never even heard this term, but I would be interested to know the context in which you heard it.
- #3
rmrramani
- 17
- 0
its similar to static indeterminancy,i red in (that word only i got)TH.megson(structural and stress analysis)
- #4
Studiot
- 5,440
- 11
It's a structural engineering term.
Look at the attached sketches.
(1) This situation is called Statically Determinate.
Shows a simple pin jointed truss with 5 members.
It is supported at A and B and loaded in some way at D
It is also restrained from sideways movement at A, or load L would just push it sideways.
This is a structure because it does not change shape in response to load L. It remains a rectangle with one diagonal.
Since there are just enough equilibrium equations (horizontal, vertical and moments) we can completely determined the forces in the members, given L and the dimensions.
(2) This situation is called Statically Indeterminate.
Shows the same thing with one extra diagonal member added.
A little calculation will show that we no longer have enough equations to uniquely determine the member forces, although the reactions will not have changed.
(3) This situation is called Kinematically Indeterminate.
The same rectangle, but we have taken away both diagonals. This is no longer a structure it is now a mechanism because it can (and will) change shape to a parallelogram in response to load L.
Although it remains fixed at A and B, it is not possible to determine how far the rectangle collapse from the equations of equilibrium alone. So the situation is indeterminate and the member forces cannot be calculated from equilibrium.
Look at the attached sketches.
(1) This situation is called Statically Determinate.
Shows a simple pin jointed truss with 5 members.
It is supported at A and B and loaded in some way at D
It is also restrained from sideways movement at A, or load L would just push it sideways.
This is a structure because it does not change shape in response to load L. It remains a rectangle with one diagonal.
Since there are just enough equilibrium equations (horizontal, vertical and moments) we can completely determined the forces in the members, given L and the dimensions.
(2) This situation is called Statically Indeterminate.
Shows the same thing with one extra diagonal member added.
A little calculation will show that we no longer have enough equations to uniquely determine the member forces, although the reactions will not have changed.
(3) This situation is called Kinematically Indeterminate.
The same rectangle, but we have taken away both diagonals. This is no longer a structure it is now a mechanism because it can (and will) change shape to a parallelogram in response to load L.
Although it remains fixed at A and B, it is not possible to determine how far the rectangle collapse from the equations of equilibrium alone. So the situation is indeterminate and the member forces cannot be calculated from equilibrium.
Attachments
- #5
Cyrus
- 3,246
- 17
Studiot, thank you for this reply. It is both concise and precise.
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