245 questions
2
votes
2
answers
131
views
How to calculate the gradient of a scatter graph?
I have an arguably common problem, but I don't seem to find any instruction on the web. I have a 3D Numpy array containing the coordinates of N points:
In[1]: import numpy as np
In[2]: N = 50
In[3]: ...
Tooling
0
votes
2
replies
49
views
OpenSCAD. A way to assign materials
I want to try out structure design. What i've done by far is a SCAD model for four trays and a cover above them.
// PARAMETERS
Length = 2000;
Width = 225;
Height = 38;
Wall = 2;
CoverThickness = 5;
...
- 1,057
0
votes
0
answers
39
views
Obtain a property value for each individual element
I have meshed a model in COMSOL and want to extract stress values for each mesh element—one value per element. For example, with 1000 meshes, I need 1000 stress values corresponding to each mesh. The ...
0
votes
0
answers
27
views
Is there a way to convert wireframe models to solid, watertight exports for FEA
I've been trying to convert this wireframe into a solid 3d model for finite element analysis and I'm just lost. Here's the code and an image of the wireframe and thank you for your help :) :
...
- 23
0
votes
1
answer
42
views
Deformable body not having degrees of freedom
I'm new to the field, so I apologize if this is a basic question. I'm working with PyDrake's DeformableModel to simulate a soft joint between a rigid column and a rigid leg (both URDF files). The ...
- 1
0
votes
0
answers
51
views
Time complexity of FEM-simulation of biphasic problem
I am trying to estimate the time complexity of an FEM simulation, that solves the normal contact between a biphasic block and an rigid indenter.
Say the block has a mesh with N x N x M nodes and the ...
- 13
0
votes
0
answers
39
views
How to Apply Meshing to a Custom Abaqus Model Script?
I have written a custom Abaqus Python script that defines a pier structure consisting of a beam, column, and base using solid extrusions. The script successfully creates these parts, but I am unsure ...
2
votes
1
answer
145
views
Generalized Nonsymmetric Eigensolver Python
How do I solve a nonsymmetric eigenproblem. In terms of scipy.sparse.linalg.eigsh the matrix needs to be "real symmetric square matrix or complex Hermitian matrix A" (https://docs.scipy.org/...
- 23
0
votes
0
answers
25
views
Defining Directional Loads of Bearing on Housing Bores
I am working on a gearbox model in Abaqus CAE, where bearings are seated in bores on the housing. I need to apply forces in three directions (x, y, z) on the inner surface (highlighted) of the bores (...
- 23
0
votes
1
answer
157
views
Quad structured mesh with Gmsh using transfinite option starting from an stl file
I'm using GMSH through Python API to create a structured quadrangular mesh to perform FEM analysis of an ascending aorta for my master thesis. I have definied, on the surface of my geometry, ...
0
votes
1
answer
107
views
reverse_cuthill_mckee in scipy: how to avoid zeros on diagonal and how to get back original matrix?
I am trying to use reverse_cuthill_mckee to reduce the bandwidth of my sparse, symmetric, complex matrix and thus improve its condition number. But As I am testing on simpler matrices, it seems the ...
0
votes
1
answer
198
views
Gmsh example t4.py unable to find t4_image.png, other examples run fine
Goal is to solve my previous question Generate a mesh from my polygon geometry to iterate FEM for geometry optimization? by myself using Gmsh
I've installed Gmsh (also) 4.12.2 using pip on macOS 10.15....
- 3,835
2
votes
0
answers
33
views
Contiguos graph partitioning
I'm studying mesh partitioning and I have the following problem. Suppose that I have a connected graph $$G$$ and an initial partition vector $$P$$, where $$P_i$$ indicates if the node $$i$$ belongs to ...
- 31
2
votes
0
answers
482
views
Generate a mesh from my polygon geometry to iterate FEM for geometry optimization?
The 2D script below generates polygons in a box, which represent a cross-section of three cylindrical rings parallel to the z axis which will have voltages applied. I'll solve the Laplace equation in ...
- 3,835
0
votes
0
answers
161
views
Python based finite element solver for 2D manifold embedded in 3 dimensional space
I am trying to use the finite element method to solve the Laplace-Beltrami eigenvalue problem on a surface (i.e., a 2D dimensional manifold) embedded in 3-dimensional space, for example, the boundary ...
- 11
0
votes
1
answer
239
views
Meaning of mesh_size
In the following, does "mesh_size" refer to the maximum perimeter or maximum area of each element?
with pygmsh.geo.Geometry() as geom:
geom.add_polygon(
[
[0.0, 0.0],
...
- 101
1
vote
1
answer
211
views
Implementing domain decomposition algos as solvers vs preconditioners
Question
In learning parallel domain decomposition (DD) concepts, and subsequently interested in their implementation, the terms domain decomposition as a solver vs. as a preconditioner come up quite ...
- 714
0
votes
1
answer
963
views
How to connect a mesh using gmsh and vtk in python
I'm working on a project that creates and manipulates meshes on geometric objects using the finite element method. So far, the user imports a file (.step) and selects areas of the object to create ...
0
votes
1
answer
260
views
Lack of Finite Element Method implementations in Haskell - Any specific reasons? [closed]
I'm curious to understand why there seems to be a scarcity of Finite Element Method (FEM) implementations in Haskell, or any functional language. Given Haskell's purely functional nature, I expected ...
1
vote
1
answer
199
views
Finite Element Analysis with Gridap.jl; how to define Von Mises stresses in Linear Elasticity problem?
From the Gridap.jl tutorial, I am struggling to compute the Von Mises stresses. I would love to get the feedback from the community on how to compute the Von Mises Stresses in the correct way. In this ...
- 639
0
votes
1
answer
494
views
ABAQUS: Defining varying material properties in a single part using a point-map of values
I'm working on a project involving FEM modeling of fractured femurs to assess the performance of fracture fixation devices. Bone is a highly complex material, with bulk elastic properties that vary ...
0
votes
1
answer
55
views
FEM: computing edge values from continuous function (Whitney p-forms)
I'm writing a Finite element method based on Whitney p-forms, where the solution coefficients are defined on edges and faces.
For example, the electric field can be approximated as
vec(E) = sum e_i ...
1
vote
0
answers
295
views
How to get damping matrix for structural model in FE analysis
I need to implement in C a method of obtaining transient solution Rdm of damped FE models based on modal results R for a structural model (imported CAD geometry) defined with hysteretic (structural) ...
- 11
2
votes
1
answer
81
views
Python gekko line break in equation definition
I'm currently implementing the Galerkin-Method for finite Elements by hand and using python gekko to solve the resulting non-linear algebraic equation system. This creates no issues for small systems ...
- 174
-1
votes
1
answer
246
views
How can I modify my Abaqus python code to only extract nodeset coordinates?
Using several example scripts found online, I have managed to extract the coordinates of an Abaqus simulation from the .odb file. However, I would like to only extract the coordinates of a certain ...
1
vote
1
answer
307
views
Sparse matrix solver in java using ojAlgo library
I'm currently doing FEM calculations in java on very large square matrices with sizes up to 1M x 1M. These are very sparse though with under 10M entries. I'm using ojAlgo with the SparseStore matrix ...
- 55
1
vote
1
answer
428
views
Quad mesh for an annular disc using gmsh
I am trying to generate a quad mesh grid for an annular disc geometry. I was able to generate this mesh for a rectangular shape using gmsh:
import gmsh
import sys
gmsh.initialize()
gmsh.model.add(&...
- 198
0
votes
0
answers
112
views
finite element analysis in mathematica
I have been having trouble solving a coupled set of PDEs in mathematica (electrical current flow), and the issue appears to be in the boundary conditions. Specifically, I have PDES as follows:
sum_{i} ...
- 375
1
vote
1
answer
286
views
Using sfepy to solve a simple 2D differential euqation
I am trying to learn sfepy. To that effect I want to solve the differential equation
On a triangle domain (2D).
There';s 2 things I don't understand from reading the docs.
How do I specify a single ...
- 10k
1
vote
0
answers
153
views
1D finite element method in the Hermite basis (P3C1) - Problem of solution calculation
I am currently working on solving the problem $-\alpha u'' + \beta u = f$ with Neumann conditions on the edge, with the finite element method in MATLAB.
I managed to set up a code that works for P1 ...
- 43
2
votes
1
answer
488
views
Finite Element Analysis with Gridap.jl; how to define external forces?
I'm following this tutorial in order to try and do an FEA of a model.msh that I have to see how it would deform given different external forces in different places.
There they define the weak form as
...
- 357
0
votes
1
answer
3k
views
How to Create Piecewise Function in SymPy with Intervals
i need to create a piece-wise function inside an interval but sympy piecewise can't use and (&). I read that the function can't recieve Boolean values so I tried to add them together and it doesn'...
- 7
0
votes
1
answer
529
views
Library for numerical Integration of a function over a tetrahedron (3D)
I am looking for å python library that has a function to solve 3D integrals over a tetrahedron. I would like to be able to input four points on the form (x, y, z) and a function f(x, y, z) where f is ...
- 11
0
votes
1
answer
148
views
"Error using vertcat Dimensions of arrays being concatenated are not consistent." in matlab while using integral2
I'm coding a programme about FEM and here is my code
FEM_2D_TRI_QUA_1.m
N1=2;
N2=2;
N=2*N1*N2;
top=1;
bottom=0;
left=0;
right=1;
h1=(right-left)/N1;
h2=(top-bottom)/N2;
T=zeros(3,2*N1*N2);
N10=N1+1;
...
- 11
0
votes
1
answer
161
views
An algorithm suggestion for interpolation in a 2d plane, when the plane is in 3D space
I'm trying to find value for a point within a triangle or square. By "value" I do not mean coordinates. Suppose there is a value (number) assigned to each node of the square/triangle. The ...
- 27
0
votes
1
answer
449
views
How to setup MATLAB shape function solver
I am trying to find the shape function for a finite element analysis problem in MATLAB. The basic shape function looks like, with the boundary condition on the left. At Ni=N1, x=x1, y=y1 (the ...
- 129
0
votes
0
answers
243
views
FEA Stress plot in Python from 3 1D-arrays
I have 3 1D arrays (node x-coordinates, node y-coordinates and Von-Mises stress scalar) exported from an FEA solver.
I want to create 2D contour plots as shown below in Python:
Stress plot example
I ...
2
votes
0
answers
65
views
Is it possibile to optimize Plotly carpet rendering?
I am working on a plotter for Finite Element Method solutions. I decided to use the Plotly library because of the carpet plots. I have my data to plot and this is my result:
Flow over NACA0012
Each ...
0
votes
1
answer
272
views
Calculating thickness of 3D geometry of a model
I am doing finite element modelling. I have a geometry which does not have a uniform thickness and I want to calculate the thickness of that in 4 distinct nodes and compare it with another model. Is ...
- 1
1
vote
1
answer
1k
views
Generate unstructured surface mesh from coordinates
Problem summary
I have a rectangular prism like in the image below where I know the coordinates of the vertices.
I want to discretize the lateral faces of the prism into an unstructured surface mesh ...
- 319
0
votes
0
answers
124
views
Earthquake simulation - finite elements method (Matlab)
do you know is there's a way to simulate a earthquake with the finite elements method using the Partial Differential Equation Toolbox on Matlab ?
My goal is to visualize the amplitude of a (Rayleigh) ...
- 1
0
votes
0
answers
743
views
How to avoid accumulated error over time and "drift" in numerical time integration?
I'm coding a few programs to study structural dynamics problems, and I'm trying to understand how to estimate and minimize accumulated error over time for large-time scale calculations.
An explicit ...
0
votes
1
answer
261
views
Is it possible to write a 1D subroutine in ABAQUS?
I'm trying to write a subroutine for ABAQUS in fortran and during my research on how to write subroutines I only encountered subroutines for 3D models. So I was wandering if it's possible to make 1D ...
- 1
0
votes
0
answers
268
views
Setting Boundary Conditions in Finite Element
EDIT: See solution in the full code, following @bgb2's comment.
I'm currently trying to code a Finite Element Analysis to solve a 2D heat conduction problem. For now I'm looking at the steady state ...
- 935
1
vote
0
answers
88
views
FEM Integrating Close to Integration Points
I am working on a program that can essentially determine the electrostatic field of some arbitrarily shaped mesh with some surface charge. To test my program I make use of a cube whose left and right ...
- 45
0
votes
0
answers
140
views
Is it possible to perform a geometric non-linear analysis in Abaqus with multiple independent steps?
I am trying to analyse a large structure with multiple loading scenarios (independent - different loading directions), while considering geometric non-linearity. Using different steps is not ...
- 3
-1
votes
1
answer
43
views
Abaqus moving reaction front for a buckling Plate
I am trying simulate lithiation of a beam in Abaqus, where during this process, a plate buckles. I partitioned 3 section of the plate where the top and bottom represent the lithiated material ( ...
- 1
0
votes
1
answer
399
views
How to use two UEL in same problem in ABAQUS
I am solving a contact problem. A footing under compressive load placed over soil. I would like to use two different types of user-defined elements one for the soil and other for the footing. Please ...
1
vote
2
answers
2k
views
How to check if 4 points form a convex quadrilatera
I'm quite new to coding in general. I have found some answers for this question but the answers seem advanced for me.
I'm trying to write my own Finite Element Project. For this I would like to write ...
- 11
1
vote
1
answer
1k
views
Is three.js able to show FEA results?
I’m trying to develop an real-time wind turbine simulation Finite Element Analysis software using three.js to display the caculated 3D FEA results. Like the image one frame of FEA result.the showed 3D ...
- 33