Hi, is there a way of applying a force load for 3D linear elasticity if the node number (global) is known? I am trying to modify the minimal 3D linear elasticity code below. I took out the self weight term in the variational formulation. I remember there was a ‘pointwise’ option for Diritchlet BCs…

[image] alex24: uh = solver.solve(b, u.x.petsc_vec) This is not correct. You should just use u for everything later in your code.

See for instance [image] Point Sources (Redux) General For dolfinx 0.8.0, simply use cmap = mesh.geometry.cmap. For dolfinx main branch (future 0.9.0), a few further changes in the call to dolfinx.cpp.geometry.determine_point_ownership are required due to Make standalone …

Hi Jorgen, thank you for the prompt reply. I’m trying to assemble the linear system so I can use the following: [image] How to apply a pointwise force using dolfinx dolfinx I figured out what the mistake was. The degrees-of-freedom of the point I want to find through “rd …

[image] alex24: #A.assemble() this is the mistake. uncomment this line.

I’ve also put point sources in an extension to dolfinx: https://scientificcomputing.github.io/scifem/examples/point_source.html which goes through the approach in detail.

Hi Francesco, Thank you for the prompt reply, I fixed that error and now get the following: File ~/.local/lib/python3.10/site-packages/spyder_kernels/customize/utils.py:209 in exec_encapsulate_locals exec_fun(compile(code_ast, filename, “exec”), globals) File ~/files/fenics_point_loading_example…

Hi Jorgen, Thank you for including the example online. What is V.sub(1) doing? How can I pass a 3D force?

Hi Jorgen, I was able to write the code using the point source example and installed scifem but when I run the code I get that petsc4py.typing is not installed, even when the line “from petsc4py import PETSc” works. Traceback (most recent call last): File ~/.local/lib/python3.10/site-packages/spy…

Hi Jorgen, Thank you I got the code running that updates b using the node number (below). I’m still not able to use PointSource(), I think the error has to do with scifem not installing correctly. Two last questions: What is the difference between using create_vector(b) and assemble_vector(b)? I…

[image] alex24: Thank you for including the example online. What is V.sub(1) doing? How can I pass a 3D force? That means a force in y direction. A 3D source would just be passing in V, and the magnitude of the source. If you need different magnitudes in different direction, create one poin…

[image] alex24: File ~/.local/lib/python3.10/site-packages/spyder_kernels/customize/utils.py:209 in exec_encapsulate_locals exec_fun(compile(code_ast, filename, “exec”), globals) File ~/files/fenics_point_loading_example_2.py:19 import scifem File ~/.local/lib/python3.10/site-packages/scifem…

How to apply a force load at a known node number

General

alex24 November 8, 2024, 8:48pm 14

Hi, why was this other Fenics user assuming this?

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How to apply a force load at a known node number

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