Study of element types and mesh density
Study of element types and mesh density
(OP)
For those interested I have completed a basic study on mesh
density and element types using Calculix. The results are
here:
http://www.onlinefeasolver.com/articles/mesh.php
Let me know your feedback and if I should model any other
cases.
density and element types using Calculix. The results are
here:
http://www.onlinefeasolver.com/articles/mesh.php
Let me know your feedback and if I should model any other
cases.
Principal - http://www.OnlineFEASolver.com
General FEA Consulting Services





RE: Study of element types and mesh density
RE: Study of element types and mesh density
Principal - http://www.OnlineFEASolver.com
General FEA Consulting Services
RE: Study of element types and mesh density
corus
RE: Study of element types and mesh density
cantilever beam. They are also good if you are just looking
at relative stresses. I use them for topology optmization
and they give good results for their price. I dont see a
problem using them as long as you have several
elements through the thickness for a bending load.
My study is meant more for the new analyst looking to
understand some basic info. on mesh density and element
types. This information exists in most big companies but is
not accessible to everyone else.
Are there any benchmarks for non-linear analysis? I suppose
I could just definte non-linear materials for the
cantilever beam and load it till a hinge point develops.
Principal - http://www.OnlineFEASolver.com
General FEA Consulting Services
RE: Study of element types and mesh density
corus
RE: Study of element types and mesh density
how do your elements fair in single element tests ?
RE: Study of element types and mesh density
"About Online FEA Solver
We are a revolutionary inexpensive online service to let analysts run their large FE models on our compute servers. We use the open source Calculix FE code to solve your input decks which need to be in ABAQUS input deck format. "
Therefore, in my opinion, each of your posts is an advertisement.
RE: Study of element types and mesh density
Cheers
Greg Locock
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Study of element types and mesh density
I quite welcome any validation of the free Calculix program so if the results are available on a web site that also offers a service, then ..so what
corus
RE: Study of element types and mesh density
if you are really interested in Calculix, you might find this book interesting as well:
"The Finite Element Method for Three-Dimensional Thermomechanical Applications" by Guido Dhondt
The author, Guido Dhondt, is also one of the authors of Calculix.
This is from the book description:
"Advanced material formulations include anisotropic hyperelasticity, large strain multiplicative viscoplasticity and single crystal viscoplasticity. Finally, the methods described in the book are implemented in the finite element software CalculiX, which is freely available (www.calculix.de; the GNU General Public License applies). "
I have this book and I can say that the author has assumed the reader has an advanced math and continuum mechanics background....so, some contour plots on a web-site(which even lack a basic legend) without any precise problem statement cannot be considered FE code validation.
RE: Study of element types and mesh density
Principal - http://www.OnlineFEASolver.com
General FEA Consulting Services
RE: Study of element types and mesh density
corus
RE: Study of element types and mesh density
However, I am completely put off from going any further than the page linked because of the following:-
"....All percentages are rounded to the nearest 5 or 10, i.e 16 becomes 15 and 72 is rounded to 70. FEA results can have an inherent error of 1-2% so reporting accuracy to the nearest whole number is typically not realistic."
I get the gist of what is intended, but why compound an error before you start? I may not be qualified to offer advice on FEA matters (or rather, am not), but I am perfectly capable of interpreting all ten digits in the units column, +/- 1% or 2%.
Furthermore, this range is not conservative compared to other posts I have read here. Methinks that FEA is perhaps even more of a black art than most other engineering disciplines.
RE: Study of element types and mesh density
-geometry description of the problem domain (problem sketch)
-problem dimensionality, 2D,3D
-statement of the material behavior and the material properties
-statement reprading element type and underlying formulation:
- plane strain/stress, axissymetric, 3D, continuum , structural
- element order (linear, quandratic) and integration scheme (full, reduced, etc)
-any other consideration affecting the element performance
- element size
-clear presentation of boundary conditions
-clear presentation of the loads applied
- statement presenting the time incrementation, for non-linear problems.
- possible statement regarding the solver used
- clear presentation of the reference case used for comparison
- statement of the quantities being compared. The analysist should specify if he used any approximation. e.g. extrapolation from integration points to nodes. If some quantities are compared at certain locations, such locations should be clearly stated.
- definition of quantities being used as the accuracy measures, e.g. relative error, absolute error etc. One should present the formulas used to define such error measures since some may take into account the values sign or not.
RE: Study of element types and mesh density
here:
h
The purpose of rounding to nearest 5/10 is so the new
analyst should not think a design with 92 MPa stress is
better than a design with 94 MPa stress. For all practical
purposes the numbers are the same in FEA world. The analyst
should treat both results as the same and NOT
make a design decision solely on a relative difference of
2%.
Principal - http://www.OnlineFEASolver.com
General FEA Consulting Services
RE: Study of element types and mesh density
Whether it's advertising or not I still think it's useful to see such verification for this program as I've had people contact me on it's use. More verification would see more acceptance of this program and even a special forum here for queries on its use?
corus