difference between inventor professional - inventor nastran in cad

[mekeuro]

Good evening.

I have a question but I would like the answer of who is a user of both applications and not who knows them only by name or even never used them
I'm just approaching inventor

I did a fem analysis on a structure, a frame of 6 meters with beams in he 120b with 6 thousand kg load.

1)inventor professional (von mises 43 mpa – arrow 1.3 mm)

2)inventor nastran in cad (von mises 1.7 mpa – maximum arrow 0.1 mm )

How come all this difference on the same model with the same program?
when I went into the environment "nastran in cad" I used the command to "import" all the simulation, so I brought behind forces, constraints and contacts, therefore I created the mesh launched the calculation.
Thank you.

 

[meccanicamg]

fearfully. Different. Taking into account how the fem solutors are structured we have a direct calculation of the deformation and a reverse calculation by passing from the characteristic of the material to deduct the tensions.
being completely different the flexions surely the two models do not have the same conditions of study.
maybe different units....mm and inches.
you need to check the variables... one by one.
These are the first things to look at.
the best thing is to try on a rectangular bar where calculations by hand and then compare the fems.

 

[mekeuro]

I don't know if you know inventor in fact I wrote it below, when I went to nastran inventor in cad I used the "import from stress annalisys" button so I just threw the calculation without having to touch anything (loads, gravity constraints, contacts etc.)

 

[stefanobruno]

material?
see there is a alert on "material "

 

[meccanicamg]

I don't know if you know inventor in fact I wrote it below, when I went to nastran inventor in cad I used the "import from stress annalisys" button so I just threw the calculation without having to touch anything (loads, gravity constraints, contacts etc.)

Again, I would check what you imported. I see alerts....material and mesh....maybe it is not defined

 

[mekeuro]

that photo is not related to that analysis....I would like to read the opinion of who uses it and maybe has or has not found a difference
I also found this article on the web .... Apparently to understand is a problem to them known.

https://knowledge.autodesk.com/it/s...-between-inventor-fea-and-nastran-in-cad.html

 

[tzadik]

inventor has a specific environment for the analysis of the frames, which works with the theory of the beam and not with the finite elements (more or less as straus).

from a topological point of view, the most reliable result on traveiform parts is to use the theory of beam (considering then that reasons in the elastic field).
If you want to do a convergence analysis to figure out how to set the mesh to match the result of the beam theory with the fem you can do it... but it would not be of great interest.


if you already predict that the results lead to a plasticization of the structure... Then you need specific software.
memory in inventor materials databases there is no information on plastic behavior (plastic flow voltages with Johnson-cook models).
calculations become extremely burdensome.