I Minimal Surface shape with gravity

AI Thread Summary
Minimal surfaces represent the shortest path in surface shapes, and the influence of gravity can be used to characterize the shape of a hammock, similar to a catenary cable. The derived equation of motion indicates potential non-unique solutions, with one identified solution being a cone. However, a "2-d catenary" was not a valid solution as initially suspected. The discussion highlights that real physical properties of materials must be considered, as a flat sheet cannot distort into another shape without stretching. Resources for further engineering analysis methods, such as plate theory, are suggested for deeper understanding.
DuckAmuck
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Minimal surfaces are sort of the "shortest path" but in terms of surface shapes.
So I figured I could characterize the shape of a hammock by adding the influence of gravity, much like you can get the shape of a catenary cable (y=cosh(x)).

The equation of motion I get from the Lagrangian is:
z_x^2 + z_y^2 + 1 = z ( z_{xx} (z_y^2 + 1) + z_{yy} (z_x^2 +1) - 2 z_x z_y z_{xy} )
where z is the height of a point on the surface mapped to (x,y).

Of course, this is likely to have non-unique solutions just like other minimal surfaces.
One of the solutions I found is a cone:
z = \sqrt{x^2 + y^2}
What does *not* work as a solution is a "2-d catenary", which is what I initially suspected as solution
z = cosh(x)cosh(y)
Anyone else attempt this kind of problem? What were your findings? I'm basically just plugging things into the equation of motion and seeing if they work.
 
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You can do these types of problem for sheets of material with real physical properties using standard engineering analysis methods .

No initially flat sheet with edge restraints can distort into any other shape without some stretching of the material .
 
Would you mind linking me to a good source for this kind of engineering analysis methods?

Nidum said:
You can do these types of problem for sheets of material with real physical properties using standard engineering analysis methods .

No initially flat sheet with edge restraints can distort into any other shape without some stretching of the material .
 
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