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Eighty Years of the Finite Element Method (2022)

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Re: Eighty Years of the Finite Element Method (2022)

#41

Post by sashank_1509 »

navane wrote: post #14
eru wrote: post #12

Earlier quoted context omitted.

> 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 pro…

Also, might work for a mechanical arm the size of an arm, but not for the size of the Eiffel tower.

Eiffel Tower was built before FEM existed. In fact I doubt they even did FEM like calculations

Re: Eighty Years of the Finite Element Method (2022)

#42

Post by navane »

angry_moose wrote: post #21
navane wrote: post #13

Earlier quoted context omitted.

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…

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 horri…

I don't know how long ago you used ansys, and i definitely don't want to sell it, but you can share geometry/mesh between those "blocks" (by dragging blocks on top of each other), and you can read in result orphaned result files.

Re: Eighty Years of the Finite Element Method (2022)

#43

Post by navane »

sashank_1509 wrote: post #41
navane wrote: post #14

Earlier quoted context omitted.

Also, might work for a mechanical arm the size of an arm, but not for the size of the Eiffel tower.

Eiffel Tower was built before FEM existed. In fact I doubt they even did FEM like calculations

I ment a mechanical arm the size of the eifel tower. You don't want to iterate physical products at that size.

Re: Eighty Years of the Finite Element Method (2022)

#44

Post by formerly_proven »

master_crab wrote: post #38
weinzierl wrote: post #3

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 sur…

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’m astonished ANSYS and NASTRAN are still the only players in town. 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.

There's a bunch of open source fem solvers e.g. Calculix, Code_Aster, OpenRadioss and probably a few unmaintained forks of (NASA) NASTRAN, but there's no multiphysics package I don't think.

Re: Eighty Years of the Finite Element Method (2022)

#45

Post by somat »

antegamisou wrote: post #22
sashank_1509 wrote: post #10

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 i…

Good luck designing crash resilient structures without simulating it on FEM based software though.

The FEM is just a model of the crash resistant structure. Hopefully it will behave like the actual structure, but that is not guaranteed. We use the FEM because it is faster and cheaper than doing the tests on the actual thing. However if you have the time and money to do your crash resiliency tests on the actual product during the development phase. I expect the results would be much better.

Re: Eighty Years of the Finite Element Method (2022)

#46

Post by westurner »

From "Chaos researchers can now predict perilous points of no return" (2022) https://news.ycombinator.com/item?id=32862414 :

> FEM: Finite Element Method: https://en.wikipedia.org/wiki/Finite_element_method

>> FEM: Finite Element Method (for ~solving coupled PDEs (Partial Differential Equations))

>> FEA: Finite Element Analysis (applied FEM)

> awesome-mecheng > Finite Element Analysis: https://github.com/m2n037/awesome-mecheng#fea

And also, "Learning quantum Hamiltonians at any temperature in polynomial time" (2024) https://arxiv.org/abs/2310.02243 re: the "relaxation technique" .. https://news.ycombinator.com/item?id=40396171

Re: Eighty Years of the Finite Element Method (2022)

#47

Post by fastasucan »

akomtu wrote: post #26
angry_moose wrote: post #15

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…

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.

Interesting that this reads almost like an chatgpt prompt.

Re: Eighty Years of the Finite Element Method (2022)

#48

Post by fastasucan »

sashank_1509 wrote: post #10

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 i…

Its wrong to assume that everyone and every projects can use an iterative method with endless prototypes. Id you do I have a prototype bridge to sell you.

Re: Eighty Years of the Finite Element Method (2022)

#49

Post by kragen »

fn-mote wrote: post #35
lll-o-lll wrote: post #19

Earlier quoted context omitted.

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?

> For hobbyists, I assume we need this stack. Just curious what kind of hobby leads to a finite element analysis?

Electronics (when you start to care about EMI or antenna design), model airplanes (for aerodynamics), rocketry, machining (especially if you want to get into SPIF), robotics, 3-D printing (especially for topology optimization), basically anything that deals with designing solid structures in the physical world. Also, computer graphics, including video games.

Unfortunately the barrier to entry is too high for most hobbyists in these fields to use FEM right now.

Re: Eighty Years of the Finite Element Method (2022)

#50

Post by kragen »

navane wrote: post #43
sashank_1509 wrote: post #41

Earlier quoted context omitted.

Eiffel Tower was built before FEM existed. In fact I doubt they even did FEM like calculations

I ment a mechanical arm the size of the eifel tower. You don't want to iterate physical products at that size.

Going by Boeing vs. SpaceX, iteration seems to be the most effective approach to building robotic physical products the size of the Eiffel Tower.
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