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Torsional locomotion

Submitted by Davide Bigoni on
research
torsion beam
elasticity
propulsion
configurational forces
large deformations

Can a torque induce longitudinal motion of an elastic rod?

See the explanation and an example of use of the 'torsional gun' at http://www.ing.unitn.it/~bigoni/torsional_locomotion.html

If you're having trouble playing videos on YouTube, click here to watch it.

 

More information about my research activity can be found in http://www.ing.unitn.it/~bigoni/
More information about our experiments can be found in http://ssmg.unitn.it/

Attachment Size
Open Access article "Torsional locomotion" published in PRSA (2014) 610.18 KB
Tianxiang

Prof. Bigoni,

Thanks for posting this vedio. This is interesting. I wonder if you can help explain the following that I find it difficult to understand.

(1) When you consider the energy of the system, do you think the roller constraint does work on the rod? When the rod slides axially crossing the constrain, I feel the constaint plays a role of untwisting the rod.

(2) From the energy equation you wrote down, potential energy is -(M^2/2D)*L. There is a negative sign there. So the smaller the L, the larger the potential energy because it is less negative. I am wondering why the system favors sliding across the constrain to reduce L and increase its potential energy?  

Thanks.

Sincerely

Tianxiang Su

Thu, 10/02/2014 - 19:43 Permalink
Tianxiang

I misunstood the direction of the force P just now. Sorry about that. Let me re-write my question here:

(1) I am wondering when the rod slides across the roller constraint, does the constraint does work on the rod? The constaint applies a torque on the rod and there is a relative rotational motion between the rod and the constraint, so the constaint does work?

Thanks.

Thu, 10/02/2014 - 20:06 Permalink