Simple cantilever bar displacement not zero on fixed constrained node. (Isoparametric coord)

[devel0]

Follow image generated through this library example and the model is base on simple cantilever with the only difference within the nodal force horizontalLoad increased of 1e2 factor.

Shouldn't the beam global displacement at offset=0 where there is a fixed constrained node a zero value ?
thanks you for any hint

[epsi1on]

Hi,
recently the nuget packages are updated, is there same problem with older nuget packages like 2.0.0?

[epsi1on]

also if you could make a source code that i can run on my side and check, it also would be helpful

[devel0]

of course, this is a console mode repro ( btw note that netcore-opengl can run in linux and even windows net7 ),
following the commands to clone repro repository at the branch used for this repro and to run using dotnet ( https://dotnet.microsoft.com/en-us/download ):

git clone --branch brief-finite-element/cantilever-fixed-restraint [email protected]:devel0/repros.git
cd repros/cantilever-fixed-restraint
dotnet run

from visual studio open .csproj or from vscode open folder and accept to create assets to run the solution.
If haven't net7 could downgrade from .csproj target framework.

I tried using 2.1.0 nuget package (latest) getting same results as described in the issue.

[epsi1on]

this line of code should be changed:
System.Console.WriteLine($"beam disp at off=0 dx = {((BarElement)model.Elements[0]).GetGlobalDisplacementAt(0).DX}");
to
System.Console.WriteLine($"beam disp at off=0 dx = {((BarElement)model.Elements[0]).GetGlobalDisplacementAt(-1.0).DX}");

the coordination you pass to Element.GetGlobalDisplacementAt(double xi) is isoparametric coordination, and it is not local coordination of element.
It means start of element is x=0 and ξ=-1, middle of element is x=L/2 and ξ=0 and end of element is x=L and ξ=+1.
Note that xi do not mean x[i], it is greek letter ξ (pronounce kesi or zi or xi).
For more info see this section
you can transform between ξ and x as described in above link, also in BarElement.IsoCoordsToLocalCoords() and BarElement.LocalCoordsToIsoCoords()

[devel0]

Many thanks,

I adjusted the example and now it display data as expected.