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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)

#101

Post by V_Terranova_Jr »

tightbookkeeper wrote: post #88
drpossum wrote: post #85

Earlier quoted context omitted.

Having worked on the design of safety structures with mechanical engineers for a few projects, it is far, far cheaper to do a simulation and iterate over designs and situations than do that in a lab or work it out by hand. The type of stuff you can do on paper without FEM tends to be significantly oversimplified. It doesn't replace things like actual tests, but it makes designing and understanding testing more effici…

> It is also much easier to convince reviewers you've done your job correctly with them. In other words, the work that doesn't change the underlying reality of the product? > We did "just fine" without cars for the majority of humanity We went to the moon, invented aircraft, bridges, skyscrapers, etc, all without FEM. So that's why this is a bad comparison. > If you asked a mechanical engineer to ignore those tools i…

What is your actual assertion? That tools like FEA are needless frippery or that they just dumb down practitioners who could have otherwise accomplished the same things with hand methods? Something else? You're replying to a practicing mechanical engineer whose experience rings true to this aerospace engineer.

Things like modern automotive structural safety or passenger aircraft safety are leagues better today than even as recently as the 1980s because engineers can perform many high-fidelity simulations long before they get to integrated system test. When integrated system test is so expensive, you're not going to explore a lot of new ideas that way.

The argument that computational tools are eroding deep engineering understanding is long-standing, and has aspects of both truth and falsity. Yep, they designed the SR-71 without FEA, but you would never do that today because for the same inflation-adjusted budget, we'd expect a lot more out of the design. Tools like FEA are what help engineers fulfill those expectations today.

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

#102

Post by MakerSam »

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…

stagnate last 15 years??? Contact elements, bolt preload, modeling individual composite fibers, delamination progressive ply failure, modeling layers of material to a few thousandths of an inch. Design optimization. ANSYS Workbench = FEA For Dummies. The list goes on.

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

#103

Post by tightbookkeeper »

V_Terranova_Jr wrote: post #101
tightbookkeeper wrote: post #88

Earlier quoted context omitted.

> It is also much easier to convince reviewers you've done your job correctly with them. In other words, the work that doesn't change the underlying reality of the product? > We did "just fine" without cars for the majority of humanity We went to the moon, invented aircraft, bridges, skyscrapers, etc, all without FEM. So that's why this is a bad comparison. > If you asked a mechanical engineer to ignore those tools i…

What is your actual assertion? That tools like FEA are needless frippery or that they just dumb down practitioners who could have otherwise accomplished the same things with hand methods? Something else? You're replying to a practicing mechanical engineer whose experience rings true to this aerospace engineer. Things like modern automotive structural safety or passenger aircraft safety are leagues better today than e…

> What is your actual assertion?

That the original comment I replied to is false: "Good luck designing crash resilient structures without simulating it on FEM based software."

Now what's my opinion? FEM raises the quality floor of engineering output overall, and more rarely the ceiling. But, excessive reliance on computer simulation often incentivizes complex, fragile, and expensive designs.

> passenger aircraft safety are leagues better today

Yep, but that's just restating the pros. Local iteration and testing.

> You're replying to a practicing mechanical engineer

Oh drpossum and I are getting to know each other.

I agree with his main point. It's an essential tool for combatting certifications and reviews in the world of increasing regulatory and policy based governance.

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

#104

Post by dark__paladin »

faustlast wrote: post #92
greesil wrote: post #5

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.

I learned from the structural engineering perspective. What are you struggling with? In my mind I have this logic flow: 1. strong form pde; 2. weak form; 3. discretized weak form; 4. compute integrals (numerically) over each element; 5. assemble the linear system; 6. solve the linear system.

Do you have any textbook recommendations for the structural engineering perspective?

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

#105

Post by albrewer »

digdugdirk wrote: post #53
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…

I'm a mechanical engineer, and I've been wanting to better understand the computational side of the tools I use every day. Do you have any recommendations for learning resources if one wanted to "relearn" FEA from a computer science perspective?

I learned it for the first time from this[0] course; part of the course covers deal.ii[1] where you program the stuff you're learning in C++.

[0]: https://open.umich.edu/find/open-educational-resources/engin...

[1]: https://www.dealii.org/

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

#106

Post by V_Terranova_Jr »

tightbookkeeper wrote: post #103
V_Terranova_Jr wrote: post #101

Earlier quoted context omitted.

What is your actual assertion? That tools like FEA are needless frippery or that they just dumb down practitioners who could have otherwise accomplished the same things with hand methods? Something else? You're replying to a practicing mechanical engineer whose experience rings true to this aerospace engineer. Things like modern automotive structural safety or passenger aircraft safety are leagues better today than e…

> What is your actual assertion? That the original comment I replied to is false: "Good luck designing crash resilient structures without simulating it on FEM based software." Now what's my opinion? FEM raises the quality floor of engineering output overall, and more rarely the ceiling. But, excessive reliance on computer simulation often incentivizes complex, fragile, and expensive designs. > passenger aircraft safe…

Replying to finish a discussion no one will probably see, but...

> That the original comment I replied to is false: "Good luck designing crash resilient structures without simulating it on FEM based software."

In refuting the original casually-worded blanket statement, yes, you're right. You can indeed design crash resilient structures without FEA. Especially if they are terrestrial (i.e., civil engineering).

In high-performance applications like aerospace vehicles (excluding general aviation) or automobiles, you will not achieve the required performance on any kind of acceptable timeline or budget without FEA. In these kinds of high-performance applications, the original statement is valid.

> FEM raises the quality floor of engineering output overall, and more rarely the ceiling. But, excessive reliance on computer simulation often incentivizes complex, fragile, and expensive designs.

Do you have any experience in aerospace applications? Because quite often, we reliably achieve structural efficiencies, at prescribed levels of robustness, that we would not achieve sans FEA. It's a matter of making the performance bar, not a matter of simple vs. complex solutions.

> I agree with his main point. It's an essential tool for combatting certifications and reviews in the world of increasing regulatory and policy based governance.

That was one of his points, not the main one. The idea that its primary value is pandering to paper-pushing regulatory bodies and "policy based governance" is specious. Does it help with your certification case? Of course. But the real value is that analyses from these tools are the substantiation we use to determine the if the (expensive) design will meet requirements and survive all its stressing load cases before we approve building it. We then have a high likelihood of what we build, assuming it conforms to design intent, performing as expected.

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