cassone alare anime e solette: warping e shear lag

[whaz86]

Hi, guys.

Here I am with a little fem project

the idea is to make a simplified cassone, rectangular shape, 4 suns at the top and 2 reinforcement currents in the middle of the panels and to load it with a cutting stress and a torque moment at the free end.
there is a similar topic, only that the chosen geometry is cylindrical.

the chosen software is femap, measuring units n,mm,kg

draw the surface (firstly, I have to close it all or leave the face to be bound open?) here is the first question: assign the properties to the model.
I better explain, I have to consider the suns as "rod", the currents as "beam", the panels like "sheal panel" and the longheroni as "plate" or do otherwise?

As for analysis and post processing we talk about it after:smile:

thanks early for support

 

[whaz86]

for completeness of information I also have the possibility to carry out the project in patran

 

[whaz86]

first draft made, no fatal error (both xdb that analysis turn)

the loads I took them from examples carried out while for the data of the model I went to feeling (then will be inserted more plausible values in case the used ones turned out wrong)

what I ask you is whether conceptually the speech is correct or if I have done a full draft
Annex I put bdf and f06

Thank you.

 

[whaz86]

Perhaps I will seem petulent but I have addressed to the forum, as such, precisely to have clarifications
Is there no one who can help me?

I would be very interested to have other feedback about the model, about the congruence or not of the work and the mistakes to correct

In short, let's discuss

 

[whaz86]

I shaped the stiffening suns (the central currents) with bar2 properties and coating (pannelli and longheroni) as shell
and here we are

the doubt I have now is how to model the 4 summit suns
I'll explain better. These suns absorb both axial stresses due to the applied torque and flexional stress due to the cutting, then use as rod or bar2 properties?

 

[whaz86]

returning to bomb on the annexed round the two revised and correct configurations, hopefully

Can someone kindly confirm or is it a pile of idiocy? :biggrin:

 

[essebi]

I can't import the db patran, if you place the bdf as the other example I take a look

 

[whaz86]

I can't import the db patran, if you place the bdf as the other example I take a look

Thank you for your interest

here are the files (I also put the f06)

I then analyzed the cases where the loads act separately, but the basic speech should be the same

 

[whaz86]

to plot the movements along a direction in the graph menu (x,y) select "displacement" for the y and path lenght for the x

but to see the trend of sigma and tau in the soles after warping?
"stress tensor" selections?

 

[Onda]

Hi.
If you don't ask a specific question, it's hard for someone to fix your homework. reason why the answers latish.
If you have a problem, which might interest others, you'll see the answers are not missing, but so. Who do you think dives your head in your model?
The units you use are not congruent. If you use mm and n, you must use the tons for the masses, or settmass =0.001 and then turn the kg into ton in the analysis, but leave them in kg in patran.

about the question you ask, rod or bar.
rods carry the axial load while bars also carry the flexional, you see what best approximates the behavior of your components.
preciselycopying from http://www.aero.polimi.it/~lanz/bacheca/downloads/cost/aa10_11/md_nastran_elements_2.pdf)

● guidelines on 1-d element selection:
● in general, select the simplest element which gives you the correct load path. more complex elements will still do the job, but may give you a lot of unwanted output.
● if only an axial load or torsional load is to be tr
ansmitted in an element, then the crod or conrod element is the best choice.
● if shear and moment are to be transmitted in an element, then the cbar is the easiest element to use.
● use the cbeam element instead of the cbar element for the
following reasons:
● variable cross-section
● the neutral axis and shear center are not coincident
● the effect of cross-sectional warping on the torsional stiffness is significant
● the mass center of gravity and shear center are not coincident
● the effect of taper on the transverse shear stiffness (shear relief) is significant

 

[whaz86]

Hi.
If you don't ask a specific question, it's hard for someone to fix your homework. reason why the answers latish.
If you have a problem, which might interest others, you'll see the answers are not missing, but so. Who do you think dives your head in your model?
The units you use are not congruent. If you use mm and n, you must use the tons for the masses, or settmass =0.001 and then turn the kg into ton in the analysis, but leave them in kg in patran.

about the question you ask, rod or bar.
rods carry the axial load while bars also carry the flexional, you see what best approximates the behavior of your components.
preciselycopying from http://www.aero.polimi.it/~lanz/bacheca/downloads/cost/aa10_11/md_nastran_elements_2.pdf)

● guidelines on 1-d element selection:
● in general, select the simplest element which gives you the correct load path. more complex elements will still do the job, but may give you a lot of unwanted output.
● if only an axial load or torsional load is to be tr
ansmitted in an element, then the crod or conrod element is the best choice.
● if shear and moment are to be transmitted in an element, then the cbar is the easiest element to use.
● use the cbeam element instead of the cbar element for the
following reasons:
● variable cross-section
● the neutral axis and shear center are not coincident
● the effect of cross-sectional warping on the torsional stiffness is significant
● the mass center of gravity and shear center are not coincident
● the effect of taper on the transverse shear stiffness (shear relief) is significant

I've reviewed the model a bit, the previous ones are no longer valid

Anyway
I don't know why he wrote kg in the first post, actually then I used the tons

I used the beam element (1d), four suns in the tops and two double t to simulate currents
the cores, both vertical and horizontal, were shaped with the shell element (2d)
should be correct

modeled the torque moment through 2 forces, while I framed one end leaving the other free

the question is:

instead wanting to plot the distribution of sigma and tau along one of the soles (or in the souls) due to warping which option to insert in the "results" drop-down menu?

specifically the steps are:
results--
for x choose path length
for y?

insert a screen in case you don't understand

per vedere la fuoriuscita ad es inserisco y=displacement translational e x=asse y

 

[Mark87g]

I also have the first weapons with the software (patran) and I would like to have if possible a list where it is written, by thread and by sign, how to make it congruent with the units of measurement. Is there anything you can do for me? For example I can use inches for lengths, pound for forces, psi for pressure. in this case am I congruent? I think so. However, in any case I would like to understand how to "invent" all units of measurement without wrong. if I use mm for lengths, n for forces, and for pressure should I use n/m^2, correct? are these the main things from which all the other greatnesses are obtained? thank you all,

 

[whaz86]

I also have the first weapons with the software (patran) and I would like to have if possible a list where it is written, by thread and by sign, how to make it congruent with the units of measurement. Is there anything you can do for me? For example I can use inches for lengths, pound for forces, psi for pressure. in this case am I congruent? I think so. However, in any case I would like to understand how to "invent" all units of measurement without wrong. if I use mm for lengths, n for forces, and for pressure should I use n/m^2, correct? are these the main things from which all the other greatnesses are obtained? thank you all,

even if the page refers to ls dyna I think the speech is worth the same for patranhttp://www.dynasupport.com/howtos/general/consistent-units