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I am looking for ideas for the following. I want to design a flexible plate where I can control the bending of the plate. In particular, a 5”x2” plate will be used which can be bent with some attached mechanisms. The plate will be dragged in water so it should not buckle under water pressure itself, rather its buckling should be controllable. I know there are certain shape memory alloys which can do that when powered (may be some piezoelectric actuator can do this also, I am not sure).

enter image description here

Can it be designed with some actuating mechanism like this below: enter image description here

I would appreciate your comments and suggestion. Thanks

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There are some works by professor Wiciak, where vibrations or noise are controlled by piezoelements. Development of noise reduction panel using piezoelectric material Piezomaterials can be used for active vibration control. Maybe you could apply this principle to this problem. How about bimetal? Can you use heat? Or cooling of predeformed shape?

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  • $\begingroup$ A link to Prof Wiciak & some of his works would improve this answer. $\endgroup$ – Fred Nov 20 '17 at 22:38
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You will want to choose a thickness of plate to resist the water flow conditions, then select an acuator with enough force to deflect the plate.

Your stroke length will be set by how much deflection you need. Your actuator type will be selected based on the required accuracy and budget.

Pizeo would work great since it is the highest accuracy and waterproof(probably only very clean water though). I probably wouldnt mess with shape memory alloys as that is likely to introduce more complexity into a simple design requirement. A gear motor linear actuator would work well too if the accuracy is sufficent and it can be kept out of the water. Radio controlled servo actuators come in a wide range of torques and accuracies would also likely work. Possibly hydraulics if the location is to hazardous for electric actuators.

As far as attaching the actuator; the easiest would be in tension like you show. Piano wire could be used to allow the actuator to be located in a more convenient or dryer location.

The actuator could also be in compression from the end if necessary. You just need to make sure the load is pinned and loaded eccentrically so it deflects the same way every time.

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Presumably you will also want a reasonably well defined curve.

To create a smooth, repeatable and adjustable curve you will want to stay withinthe elastic limit of the the material you are using which will depend on the material itself and its thickness. Steel or a composite sheet would seem like reasonable candidates.

This also puts a limit on the stiffness of the surface as the elastic deformation will be limited by the thickness of the plate.

The profile you end up with can be calculated by beam deflection theory and will depend on where you apply loads, in what direction and how the ends of the plate are supported.

Probably the simplest solution is to support one end and apply a load at the other (much like your example mechanism). Although there are lots of potential permutations of load and support arrangements.

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