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my question is as follows: could the stresses on a solid body be aproximated with a discrete model based on trusses?, this is, that the result yielded by the analysis of the truss structure will resemble the actual stress distribution?

And does this have something in common with fea modelling(meshing)?

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  • $\begingroup$ Depending on the type of network interaction, the Poisson's ratio of a discrete spring network is either 0.25 or 0.33. You have to keep that in mind when applying any such analogy. $\endgroup$ Jul 31 '21 at 4:27
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Not only can this be done, but it also is done for concrete structures all the time.

The shear reinforcement in concrete beams is calculated using Mörsch's truss analogy model:

enter image description here Source

The concrete beam is simplified into a truss, where the upper chord (under compression) is the concrete itself, the lower chord (under tension) is the longitudinal reinforcement and the verticals are the shear reinforcement.

Now, to be clear, this model effectively calculates the shear force that must be resisted by the stirrups, not the shear stress. But the concept is the same.

And yes, this is similar to FEA. FEA is basically the creation of a really messy truss (aka, the mesh). You then calculate the deflections of each of the tiny "bars" that compose the mesh, and then some fancy math lets you convert that to stresses within each of the cells.

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  • $\begingroup$ I agree some of the original FE software did things analogous to representing an "element" with some sort of equivalent truss, but it went out of fashion about 50 years ago. The truss analogy for concrete is useful because most civil engineering concrete structures are geometrically simple. Don't try modelling a shape with curved edges that way! $\endgroup$
    – alephzero
    Jul 31 '21 at 16:44

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