DomP
Bioengineer
- Jul 30, 2015
- 2
Hi all,
I just discovered this forum, great threads!
I would like to continue the discussions of these two previous discussions with a new parameter: the speed of snapping.
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Let's say we have a bi-stable structure with an OD of 30mm (1.18in), the structure could be a spherical cap (dome type) with or without center hole, or a belleville washer (conical). As per previous discussion, the ratio of the height over the thickness h/t must be high enough to have a bistable structure.
Question: How the dome/washer should be designed in order to provide the highest speed of snapping with a minimal force of triggering (loaded to unloaded (ie. initially stamped) state? The force to load the dome/washer and the height of the structure do not matter.
We are looking at a very asymmetrical bistable structure, with a high residual stress in the loaded state I guess. How to achieve that?
With an insight in the stress zone, would removing some part of the dome would decrease the trigger force but keeping the speed? eg. the center
How to increase the internal stress to a level just before triggering back the dome, so that the the trigger force is low.
What equations describe the speed of such structures?
A lot of questions
One mystery: the speed & low force.
Comments welcome. Thanks!
Cheers
I just discovered this forum, great threads!
I would like to continue the discussions of these two previous discussions with a new parameter: the speed of snapping.
[ul]
[li][/li]
[li][/li]
[/ul]
Let's say we have a bi-stable structure with an OD of 30mm (1.18in), the structure could be a spherical cap (dome type) with or without center hole, or a belleville washer (conical). As per previous discussion, the ratio of the height over the thickness h/t must be high enough to have a bistable structure.
Question: How the dome/washer should be designed in order to provide the highest speed of snapping with a minimal force of triggering (loaded to unloaded (ie. initially stamped) state? The force to load the dome/washer and the height of the structure do not matter.
We are looking at a very asymmetrical bistable structure, with a high residual stress in the loaded state I guess. How to achieve that?
With an insight in the stress zone, would removing some part of the dome would decrease the trigger force but keeping the speed? eg. the center
How to increase the internal stress to a level just before triggering back the dome, so that the the trigger force is low.
What equations describe the speed of such structures?
A lot of questions
Comments welcome. Thanks!
Cheers