Finite element method and applied element method

Which method


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    4
  • #1
What are the advantages and disadvantages of both AEM and FEM and which on is easier.
I am doing a project and I should use one of these two methods to solve for a truss system.
P.S. computer programming shall be used.

In the end which method is better for this case?
 

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  • #2
SteamKing
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It depends on how far you want the analysis of the truss system to extend.

AEM is used to predict what happens after a structure is loaded beyond elastic limits and is proceeding to failure.

http://en.wikipedia.org/wiki/Applied_element_method

FEM is generally used to analyze a structure where the stresses are not assumed to be greater than the elastic limit of the material. If some FEM results are obtained which happen to show stress is greater than the elastic limit of the material, then the designer can either do a more detailed investigation (perhaps using AEM) or simply add material to the structure to bring the stresses down to acceptable levels.
 
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  • #3
AlephZero
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If you are doing a small displacement linear analysis of the truss, there is no obvious reason NOT to use FEM, and no reason to write your own software (except to teach yourself about FEM).

Looking at the references and links in the wikipedia page, I see all the referenced papers have the inventor of the method as one of the authors. The two links to software products using AEM make a lot of unsubstantiated claims about the limitation of FEM which I don't necessarily agree with, and one of the products seems to have been developed on the back of a US Dept of Homeland Security initiative, to give indemnity to developers of new technologies that might have relevance to 9-11 type events in case the technology doesn't actually work.

Sorry, but if I was going to design a conventional truss structure, I would rather use an old method that has demonstrably worked OK for at least 50 years already, rather than new one where the DHS will give me my money back if the structure fails!
 
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  • #4
No doubt about it: use FEM. There is no conceptual difference between AEM and FEM. I would even say AEM is FEM, but formulated by those who never heard about cohesive elements. They are basically the same thing, but if you are looking for a job after graduation, you better say you know about FEM and not AEM!
 
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  • #5
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FEM can do anything you want to do.

Car crash test simulations are done with high-fidelity FEM (8-noded "solid" elements) using such tools as ABAQUS, ANSYS, LS-DYNA.

Structural engineers model the beams and columns of high rise buildings (or perhaps more relevant for you: the bars of a bridge truss) using FEM ("beam" elements), with software such as ETABS, RISA, STAAD.

"Shell" elements are also commonly used, and that can be done using any of the aforementioned software. Additionally, any of the aforementioned software can simulate steel plasticity (damage). The high-fidelity software even have very good built-in capabilities for simulating things like anisotropy (wood, carbon-fiber), viscoelasticity (rubber), fracture (concrete damage), and just about anything else you can imagine.

I have not heard of "AEM" until this thread.
 
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