Finite Element Analysis (FEA): Why Is It Needed?

[koolraj09]

Hi all.
I am a mechanical engineering student and I know a bit of Finite element method. But I don't clearly appreciate the need for studying the course. Why is it important or rather why is it really needed?
Also is there a need for mechanical engineers to know compulsorily know a modeling software? If so, why?
Please help me appreciate the need for above two things.
Thanks.

 

[SteamKing]

If you don't mind trying to analyze stresses or other quantities for situations more complex than typical home work problems using hand calculations, no, you don't need to know FEA.

It's just like them oldtimers said, "Let them kids have their fancy calculators and computers. I'm keeping my trusty slide rule."

 

[Astronuc]

Hi all.
I am a mechanical engineering student and I know a bit of Finite element method. But I don't clearly appreciate the need for studying the course. Why is it important or rather why is it really needed?
Also is there a need for mechanical engineers to know compulsorily know a modeling software? If so, why?
Please help me appreciate the need for above two things.
Thanks.

Simulation enables one to numerically test/simulate a design in numerous ways and repeatedly, often beyond elastic limits, whereas a physical test would result in damage to the system. A physical test would have to be repeated with a new test specimen for each test, and such a series would be much more expensive.

Implementing FEA in the design phase allows the designer to make changes to components before committing the component to manufacture, thus it also saves money and effort.

I should point out that FEA works for computational fluid dynamics as well as mechanics/dynamics of materials/solid/structures. They may be combined to look at fluid-structure interaction.

 

[AlephZero]

I'm not sure if your "FEA course" is teaching you how to use the FE method, or how the FE method works.

If should be fairly obvious why MEs need to know how to use FE. As #2 and #3 said, the real world of engineering isn't limited to simple problems you can solve by hand.

The reason for learning how it works is maybe not quite so obvious, but if you don't understand the assumptions and limitations that are "built in" to different types of FE models and solution procedures, you can quickly get into the situation where you are not doing any sort of engineering, you are just playing with computers and producing pretty graphics, and the long-term consequence of that in the real world is usually "something bad happens".

 

[pantaz]

Here is a great real-world example of using FEA in the design of a bicycle.

Finite-Element Structural Analysis: A New Tool for Bicycle Frame Design
http://www.sheldonbrown.com/rinard/fea.htm​

 

[daveb]

As part of our developmental process at myjob, the engineers have used FEA numerous times to satisfy regulatory requirements (e.g., FDA) that cannot tested.

 

[koolraj09]

Thanks everyone. So we use FEA because the math becomes complex for real life systems such that we can't solve it by hand. Can someone suggest a good book (simple language) for FEA? I tried some but they don't have enough examples...all they have is math!

 

[Mech_Engineer]

I'll post what I did in another thread asking for an FEA book without the math...

In case you didn't realize it let me clear something up for you- finite element analysis is ALL math. You can't learn about FEA without math, period. Even if you want a book with "practical" in the name, it doesn't mean it won't cover the math aspects of FEA.

I'm a mechanical engineer, my job involves a lot of FEA analysis. Structural, thermal, electromagnetic, CFD, and coupled-physics.

https://www.physicsforums.com/showthread.php?t=399602

 

[Astronuc]

I'll post what I did in another thread asking for an FEA book without the math...

https://www.physicsforums.com/showthread.php?t=399602

Thanks for the excellent discussion on FEA and the link to the book.

From the book cite by Mech_Engineer:

Nanomechanics deals with phenomena at the molecular and atomic levels of matter. As such it is closely linked to particle physics and chemistry. Micromechanics looks primarily at the crystallographic and granular levels of matter. Its main technological application is the design and fabrication of materials and microdevices.

Continuum mechanics studies bodies at the macroscopic level, using continuum models in which the microstructure is homogenized by phenomenological averages. The two traditional areas of application are solid and fluid mechanics. The former includes structures which, for obvious reasons, are fabricated with solids. Computational solid mechanics takes an applied sciences approach, whereas computational structural mechanics emphasizes technological applications to the analysis and design of structures.

Computational fluid mechanics deals with problems that involve the equilibrium and motion of liquid and gases. Well developed subsidiaries are hydrodynamics, aerodynamics, acoustics, atmospheric physics, shock, combustion and propulsion.

Multiphysics is a more recent newcomer. This area is meant to include mechanical systems that transcend the classical boundaries of solid and fluid mechanics, as in interacting fluids and structures. Phase change problems such as ice melting and metal solidification fit into this category, as do the interaction of control, mechanical and electromagnetic systems.

Linear static analysis deals with static problems in which the response is linear in the cause-and-effect sense. For example: if the applied forces are doubled, the displacements and internal stresses also double. Problems outside this domain are classified as nonlinear.

Static systems are generally employed with significant margin to elastic limits. However over time, the boundaries may creep, or corrosion may result in material degradation that alters local stress distribution.

Power and dynamic systems often involve nonlinear mechanics as properties change with operation or during abnormal transients.

In order to effectively, or fully use FEA, one has to know the mathematics behind the modeling and simulation, as well as the physics.

 

[AlephZero]

Thanks for the excellent discussion on FEA and the link to the book.

Yup. Carlos Felippa is one of the FE gurus.

I liked his comment on the bibliography (Appendix G, IIRC): since the 1980s the FE method has become a "mathematical wasteland" for engineers. Sad, but true. It's too easy to get the wrong idea from a math-based introduction that "FE is simple" or that "more elements will always converge to the right answer".

 

[koolraj09]

Thank you all.
Like AlephZero said, our professor also led us to the "mathematical wasteland" that's why I'm a bit worried with my physics understanding of the subject.
Once again thanks everyone.