[HN Gopher] Eighty Years of the Finite Element Method (2022)
___________________________________________________________________
Eighty Years of the Finite Element Method (2022)
Author : sandwichsphinx
Score : 71 points
Date : 2024-11-02 19:23 UTC (3 hours ago)
(HTM) web link (link.springer.com)
(TXT) w3m dump (link.springer.com)
| pvg wrote:
| A 45 comment thread at the time
| https://news.ycombinator.com/item?id=33480799
| weinzierl wrote:
| I started my career doing FE modeling and analysis with ANSYS and
| NASTRAN. Sometimes I miss these days. Thinking about how to
| simplify a real world problem so far that it is solvable with the
| computational means available was always fun. Then pushing quads
| around for hours until the mesh was good had an almost meditative
| effect. But I don't feel overwhelmingly eager to learn a new
| software or language.
|
| Much to my surprise, it seems there hasn't been much movement
| there. ANSYS still seems to be the leader for general simulation
| and multi-physics. NASTRAN still popular. Still no viable open-
| source solution.
|
| The only new player seems to be COMSOL. Has anyone experience
| with it? Would it be worth a try for someone who knows ANSYS and
| NASTRAN well?
| kayo_20211030 wrote:
| As a recovering fe modeler, I understand completely.
| magicalhippo wrote:
| > Still no viable open-source solution.
|
| For the more low-level stuff there's the FEniCS project[1], for
| solving PDEs using fairly straight forward Python code like
| this[2]. When I say fairly straight forward, I mean it follows
| the math pretty closely, it's not exactly high-school level
| stuff.
|
| [1]: https://fenicsproject.org/
|
| [2]: https://jsdokken.com/dolfinx-
| tutorial/chapter2/linearelastic...
| lll-o-lll wrote:
| Interesting. Please bear with me as this is going off 25 year
| old memories, but my memory is that the workflow for using
| FEA tools was: Model in some 3D modelling engineering tool
| (e.g. SolidWorks), ansys to run FEA, iterate if needed,
| prototype, iterate.
|
| So to have anything useful, you need that entire pipeline?
| For hobbyists, I assume we need this stack. What are the
| popular modelling tools?
| magicalhippo wrote:
| Yeah not my domain so wouldn't really know. For FEniCS I
| know Gmsh[1] was used. There's some work[2][3] been done to
| integrate FEniCS with FreeCAD. It seems FreeCAD also
| supports[4] other FEM solvers.
|
| But, I guess you get what you pay for in this space still.
|
| [1]: https://gmsh.info/
|
| [2]: https://github.com/qingfengxia/Cfd
|
| [3]: https://github.com/qingfengxia/FenicsSolver
|
| [3]: https://wiki.freecad.org/FEM_Solver
| fn-mote wrote:
| > For hobbyists, I assume we need this stack.
|
| Just curious what kind of hobby leads to a finite element
| analysis?
| hhoorzad wrote:
| Abaqus is pretty big too. I've worked with both Ansys and
| Abaqus and I generally prefer the latter.
| navane wrote:
| I've used ansys daily for over a decade, and the only movement
| is in how they name their license tiers. It's a slow muddy
| death march. Every year I'm fighting the software more and
| more, the sales men are clearly at the wheel.
|
| They buy "vertical aligned" software, integrate it, then slowly
| let it die. They just announced they're killing off one of
| these next year, that they bought ten years ago, because they
| want to push a competitive product with 20% of the features.
|
| I've been using nastran for half as long but it isn't much
| better. It's all sales.
|
| I dabbed a bit in abaqus, that seems nice. Probably cause I
| just dabbed in it.
|
| But here I'm just trying to do my work, and all these companies
| do is move capabilities around their license tiers and boil the
| frog as fast as they get away with.
| angry_moose wrote:
| I've gone Abaqus > Ansys > Abaqus/LS-DYNA over my career and
| hate Ansys with a fiery passion. It's the easiest one to run
| your first model in, but when you start applying it to real
| problems its a fully adversarial relationship. The fact you
| have to make a complete copy of the geometry/mesh to a new
| Workbench "block" to run a slightly different load case (and
| you can't read in an orphaned results files) is just
| horrible.
|
| Abaqus is more difficult to get up to speed in, but its
| really nice from an advanced usability standpoint. They
| struggle due to cost though, it is hugely expensive and we've
| had to fight hard to keep it time and time again.
|
| LS-Dyna is similar to Abaqus (though I'm not fully up in it
| yet), but we're all just waiting to see how Ansys ruins it,
| especially now that they got bought out by Synopsys.
| angry_moose wrote:
| COMSOL's big advantage is it ties together _a lot_ of different
| physics regimes together and makes it very easy to couple
| different physics together. Want to do coupled structures
| /fluid? Or coupled electromagnetism/mechanical? Its probably
| the easiest one to use.
|
| Each individual physics regime is not particularly good on its
| own - there are far better mechanical, CFD, electromagnetism,
| etc solvers out there - but they're all made by different
| vendors and don't play nicely with each other.
| littlestymaar wrote:
| > The only new player seems to be COMSOL
|
| Ouch. I kind of know Comsol because it was already taught in my
| engineering school 15 years ago, so that it still counts as a
| "new entrant" really gives an idea of how slow the field
| evolves.
| petters wrote:
| The COMSOL company was started in 1986....
| master_crab wrote:
| _Still no viable open-source solution._
|
| Wait? What? NASTRAN was originally developed by NASA and open
| sourced over two decades ago. Is this commercial software built
| on top that is closed source?
|
| I remember using NASTRAN 20 years ago for FE of structures
| while doing aero engineering. And even then NASTRAN was almost
| 40 years old and ancient.
|
| I'm astonished ANSYS and NASTRAN are still the only players in
| town.
| greesil wrote:
| I took a course in undergrad, and was exposed to it in grad
| school again, and for the life of me I still don't understand the
| derivations either Galerkin or variational.
| sashank_1509 wrote:
| My hot take is that, FEM is best used as unit testing of Machine
| Design, not a guide towards design that it's often used as. The
| greatest mechanical engineer I know, once designed an entire
| mechanical wrist arm with five fingers, actuations, lots of parts
| and flexible finger tendon. He never used FEM at any part of his
| design. He instead did it in the old fashioned, design and fab a
| simple prototype, get a feel for it, use the tolerances you
| discovered in the next prototype and just keep iterating quickly.
| If I went to him and told him to model the flexor of his fingers
| in FEM, and then gave him a book to tell him how to correctly use
| the FEM software so that you got non "non-sensical" results I
| would have slowed him down if anything. Just build and you learn
| the tolerances, and the skill is in building many cheap
| prototypes to get the best idea of what the final expensive build
| will look like.
| eru wrote:
| > The greatest mechanical engineer I know, [...]
|
| And with that you wrote the best reply to your own comment.
| Great programmers of the past wrote amazing systems just in
| assembly. But you needed to be a great programmer just to get
| anything done at all.
|
| Nowadays dunces like me can write reasonable software in high
| level languages with plenty of libraries. That's progress.
|
| Similar for mechanical engineering.
|
| (Doing prototypes etc might still be a good idea, of course. My
| argument is mainly that what works for the best engineers
| doesn't necessarily work for the masses.)
| navane wrote:
| Also, might work for a mechanical arm the size of an arm, but
| not for the size of the Eiffel tower.
| fluorinerocket wrote:
| Would FEM be useful for that kind problem? It's more for
| figuring out if your structure will take the load, where stress
| concentrations are, what happens with thermal expansion. FEM
| won't do much for figuring out what the tolerance need to be on
| intricate mechanisms
| NathanaelRea wrote:
| Garbage in garbage out. If you don't fully understand the
| model, then small parameter changes can create wildly different
| results. It's always good to go back to fundamentals and hand
| check a simplification to get a feel for how it should behave.
| antegamisou wrote:
| Good luck designing crash resilient structures without
| simulating it on FEM based software though.
| tightbookkeeper wrote:
| They did this just fine until without such tools for the
| majority of innovation in the last century.
| angry_moose wrote:
| To be fair, FEM is not the right tool for mechanical linkage
| design (if anything, you'd use rigid body dynamics).
|
| FEM is the tool you'd use to tell when and where the mechanical
| linkage assembly will break.
| amelius wrote:
| If he were designing a bridge, however ...
| kaonwarb wrote:
| I also studied FEM in undergrad and grad school. There's
| something very satisfying about breaking an intractably difficult
| real-world problem up into finite chunks of simplified, simulated
| reality and getting a useful, albeit explicitly imperfect, answer
| out of the other end. I find myself thinking about this approach
| often.
| angry_moose wrote:
| I've been a full-time FEM Analyst for 15 years now. It's
| generally a nice article, though in my opinion paints a far
| rosier picture of the last couple decades than is warranted.
|
| Actual, practical use of FEM has been stagnate for quite some
| time. There have been some nice stability improvements to the
| numerical algorithms that make highly nonlinear problems a little
| easier; solvers are more optimized; and hardware is of course
| dramatically more capable (flash storage has been a godsend).
|
| Basically every advanced/"next generation" thing the article
| touts has fallen flat on its face when applied to real problems.
| They have some nice results on the world's simplest "laboratory"
| problem, but accuracy is abysmal on most real-world problems -
| e.g. it might give good results on a cylinder in simple tension,
| but fails horribly when adding bending.
|
| There's still nothing better, but looking back I'm pretty
| surprised I'm still basically doing things the same way I was as
| an Engineer 1; and not for lack of trying. I've been on countless
| development projects that seem promising but just won't validate
| in the real world.
|
| Industry focus has been far more on Verification and Validation
| (ASME V&V 10/20/40) which has done a lot to point out the various
| pitfalls and limitations. Academic research and the software
| vendors haven't been particularly keen to revisit the supposedly
| "solved" problems we're finding.
| catgary wrote:
| I kind of thought Neural Operators were slotting into the some
| problem domains where FEM is used (based on recent work in
| weather modelling, cloth modelling, etc) and thought there was
| some sort of FEM -> NO lineage. Did I completely misunderstand
| that whole thing?
| angry_moose wrote:
| Those are definitely up next in the flashy-new-thing pipeline
| and I'm not that up to speed on them yet.
|
| Another group within my company is evaluating them right now
| and the early results seems to be "not very accurate, but
| directionally correct and very fast" so there may be some
| value in non-FEM experts using them to quickly tell if A or B
| is a better design; but will still need a more proper
| analysis in more accurate tools.
|
| It's still early though and we're just starting to see the
| first non-research solvers hitting the market.
| amelius wrote:
| I was under the impression that the linear systems that come
| out of FEM methods are in some cases being solved by neural
| networks (or partially, e.g. as a preconditioner in an
| iterative scheme), but I don't know the details.
| akomtu wrote:
| Could you write a blogpost-style article on how to model the
| shallow water wave equation on a sphere? The article would
| start with the simplest possible method, something that could
| be implemented in short C program, and would continue with a
| progressively more accurate and complex methods.
| neumann wrote:
| If you are interested in this, I'd recommend following an
| openfoam tutorial, c++ though.
|
| You could do SWE with finite elements, but generally finite
| volumes would be your choice to handle any potential
| discontinuities and is more stable and accurate for practical
| problems.
|
| Here is a tutorial. https://www.tfd.chalmers.se/~hani/kurser/
| OS_CFD_2010/johanPi...
| ccosm wrote:
| >Basically every advanced/"next generation" thing the article
| touts has fallen flat on its face when applied to real problems
|
| Even Arnold's work? FEEC seemed quite promising last time I was
| reading about it, but never seemed to get much traction in the
| wider FEM world.
| mlhpdx wrote:
| I have such a fondness for FEA. ANSYS and COSMOS were the ones I
| used, and I've written toy modelers and solvers (one for my HP
| 48g) and even tinkered with using GPUs for getting answers faster
| (back in the early 2000s).
|
| Unfortunately my experience is that FEA is a blunt instrument
| with narrow practical applications. Where it's needed, it is
| absolutely fantastic. Where it's used when it isn't needed, it's
| quite the albatross.
| cyberax wrote:
| FEM - because we can't solve PDEs!
| niraj-agarwal wrote:
| Predicting how things evolve in space-time is a fundamental need.
| Finite element methods deserve the glory of a place at the top of
| the HN list. I opted for "orthogonal collocation" as the method
| of choice for my model back in the day because it was faster and
| more fitting to the problem at hand. A couple of my fellow
| researchers did use FEM. It was all the rage in the 90s for sure.
___________________________________________________________________
(page generated 2024-11-02 23:00 UTC)