Engineer43

Best lattice structure/geometry for strength and minimal heat transfer?

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Posted (edited)

I'm currently trying to choose a lattice structure/geometry that finds the tradeoff between strength (for compression & shear mostly) and heat transfer. I want to maximize strength and minimize heat transfer through the lattice. Does anyone have any recommendations on this front?

The less material, the better!

Thanks a ton in advance.

Edited by Engineer43
The wording was slightly weird.

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Isn't that kind of dependent on what the lattice is being used for? A spherical object loses less heat than any other shape (less surface area) but is difficult to make with a lattice. Seems to me, something in the shape of a buckyball (or if you want to be technical a buckminsterfullerene) would be the best for both strength and retarding heat transfer.  https://en.wikipedia.org/wiki/Buckminsterfullerene

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I understand "conductive transfer". Right?

You must first optimize the structure. A truss is a good start, but telling which is best needs to know what the forces and dimensions are. If the forces are tiny in a big volume, just straps that pull the object are better
https://www.scienceforums.net/topic/60359-extruded-rocket-structure/page/2/?tab=comments#comment-761740

Once the shape is optimum you must choose a material that is strong (and possibly stiff) but conducts little heat. Both the strength and the heat conduction follow the same law proportional to S/L so what counts is the material's ratio: strength to conductivity. Titanium alloys are not bad for that, fibreglass composites are good, aramide too.

What kind of shape and force concentration is possible depends on the material, so designing needs to go back and forth between shape and material.

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The OP wrote "strength", not stiffness, and strength doesn't depend on parts length if extended or compressed. One first element of answer is then to make parts longer.

A truss construction that loads the elements only axially is better. Bending for instance is much worse, as it amplifies the stresses a lot but doesn't isolate, so the bigger cross-areas conduct more heat.

Though, everything depends completely on individual cases, especially the concentration of the forces. How much conduction is accepted is quite important too. "Maximize this and minimize that" is a counter-productive information in engineering that often leads to uselessly complicated designs.

And whether the solution uses titanium, stainless steel, aramide belts, glued spruce, a truss of thin electrodeposited nickel tubes, plastic foam or cork depends on the needs. Obviously the shape won't be the same then. Whether air convection is acceptable matters a lot too.

So Engineer43, could you at least tell the forces, the accepted heat transfer, the warm and cold temperatures, the dimensions, mass...? Or far better, describe your project. For a satellite, we afford designs and production methods inadequate for a fridge.

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On 7/9/2019 at 7:48 PM, Engineer43 said:

I'm currently trying to choose a lattice structure/geometry that finds the tradeoff between strength (for compression & shear mostly) and heat transfer. I want to maximize strength and minimize heat transfer through the lattice. Does anyone have any recommendations on this front?

The less material, the better!

Thanks a ton in advance.

 

This is an interesting question to discuss although it is probably too late since you haven't look back since the day after you first posted.

I think this is key

On 7/28/2019 at 3:44 AM, npts2020 said:

Isn't that kind of dependent on what the lattice is being used for?

and I would add to that the question

What do is meant by lattice?

Does this refer to the physical arrangement of atoms or a truss arrangement of structural components of some sort?

 

Various deductions as to the use can be made from the all too limited information provided, especially since the main load is described as compression / shear, which will be at direct odds with the low thermal conductivity requirement.
Various lamination schemes may be proposed to address this, but details will depend upon more complete and exact information being supplied.

 

To others:

Is it worth continuing this discussion?

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