msc

[whaz86]

Hello everyone, I find myself having to work with this software package in the perspective of a future analysis of the behavior of a winglet

being practically fast of this package and having not found anything around (in terms of tutorials or examples) I address to you; is there someone who has familiarity with the aeroelastic aspect of the program?

more specifically by asking some questions

1) the aero modeling menu allows me to define the geometry of interest (superf carrier or others), can I also import models already created in patran?

2) after creating the aerodynamic model step to the creation of the spline (aerostructure-coupling) where it asks me to insert structural points e aero bodies; in the first I should put the knots of the model, but in the second?

3) I must also assign aero monitor points and structural monitor points?

 

[whaz86]

Okay, overcome these 3 obstacles

wanting to do flutter analysis of a plate get the following warning in the f06 file

user warning message 4124 (ifs3p)
the spcadd or mpcadd union consists of a single set

What does it depend on?
the analysis turns, as it calculates the frequencies and does not give fatal errors

wanting instead to study the flutter for a beam I get besides said warning also the following error

system fatal message 3002 (apd)
eof encountered while reading data block aecstm (file 207) in subroutine wrcstm



in both cases with flightloads I can't do the actachment after analysis to see the results
the only 2 possibilities are
xdb attachment
air attack

with possible choices
both
result date
model date

 

[whaz86]

place the bdf and the f06 files, the values of the parameters will probably be little consons but I am also working on that;
at the moment my purpose is to understand the procedure to be implemented

in bdf I don't get fatal errors or warnings, as well as in f06, but I still can't do the xdb file attack anyway
if instead I choose to generate a file op2 the f06 gives me different errors

What are the mistakes I make?

 

[Onda]

try to put
param post -1

instead of
param post 0

In the bdf and twist it, I have no aeroelastic license and I can't turn it, at least though you should pull out the op2.

because by doing the xdb it seems to me that it comes to the bottom, but it seems to me to remember that with the aircraft you have to do the op2 by force.
so if you change the parameter directly into the bdf you should get the op2 done directly.

Didn't you do that file?
there is the parameter param wtmass .00259

typical of Anglo-Saxon units.

 

[whaz86]

try to put
param post -1

instead of
param post 0

In the bdf and twist it, I have no aeroelastic license and I can't turn it, at least though you should pull out the op2.

because by doing the xdb it seems to me that it comes to the bottom, but it seems to me to remember that with the aircraft you have to do the op2 by force.
so if you change the parameter directly into the bdf you should get the op2 done directly.

Didn't you do that file?
there is the parameter param wtmass .00259

typical of Anglo-Saxon units.

actually in the bdf tied to the file op2 the string param post is already set to -1, for the rest is equal to the dbf attached first
still have the same errors in the f06 file

the file is made by me, having to arrange alone I based on how much found on the net
so for the param wtmass should I leave the value 1 by default?

Thank you.

 

[Onda]

Unfortunately, for the aircraft, I'm of little help, it's not exactly a common analysis. .
As for wtmass, this is a conversion factor that is used to make the units of measure congruent.
what you used is for inch/pounds models.
I normally make models in mm, masses in kg, accelerations in mm/sec.
use wtmass to 0.001 to convert the masses from kg to tons and make them congruent with the units' measurement.
if instead models in meters and kg, wtmass must be equal to 1.

 

[whaz86]

Unfortunately, for the aircraft, I'm of little help, it's not exactly a common analysis. .
As for wtmass, this is a conversion factor that is used to make the units of measure congruent.
what you used is for inch/pounds models.
I normally make models in mm, masses in kg, accelerations in mm/sec.
use wtmass to 0.001 to convert the masses from kg to tons and make them congruent with the units' measurement.
if instead models in meters and kg, wtmass must be equal to 1.

in fact even asking around looked strange when I mentioned flightloads; I'm gonna have to take care of myself.
as if it wasn't enough then I was also asked to use the support zaero software, software that obviously nobody knows

In one way or another I will come to the head
thank you very much for the clarification

 

[Onda]

Mah, keep posting, you never know that something doesn't come out, sincerely I care, and I also studied something, but it's not that I understand every day. .

 

[whaz86]

after a few days of inactivity I returned to the model and seems to have come to a positive solution; I can do the attraction and see the motorists in the results menu

now to see graphically if I have flutter I should do the diagrams (motoring and frequency according to the speed of the modes), and note if for some solution you cancel the damping, the imaginary part

Can I do it on patran or do I have to pass through punch file and bring back the autovalues in excel or matlab?

 

[whaz86]

place here since we are on the theme (although the model I wrote it manually without passing by patran)

the idea was to model a wing with winglet and make a flutter analysis (sol 145)

I created the grid of the knots of the wing plan connecting then with shell elements
for winglet the process was the same, only that I first entered a new sist coordinates (command cord2r) otherwise the .f06 file gave me problems with the spline
then I entered the aerodynamic panels

the analysis turns and I can pull out the charts of damping and frequencies according to the speed

the doubt concerns the .xdb file imported then in flightloads
Specifically, once imported the file (both=model+results) going to display the known results that it is as if the wing and winglet were untied, the structure does not move all together

I wonder if it is normal that it is so (maybe it is due to aerodynamic paneling) or there is a mistake

 

[whaz86]

place two pictures to clarify the speech

the first is referred to a model consisting of shell elements on which the aerodynamic modeling was made
the second is related to a transform model to which the aerodynamic one has been added
as you see it seems that the winglet is detached from the wing
I wonder whether it is due to the flightloads or if particular conditions of constraint are to be inserted

 

[Onda]

are the knots of the aerodynamic and structural model in common? How are the two knots connected to each other?

are the same knots?

 

[whaz86]

are the knots of the aerodynamic and structural model in common? How are the two knots connected to each other?

are the same knots?

I wrote it in nastran
are 24 knots for wing and 5 for winglet in the first case

for the beam I used 21 knots + 1 for winglet (I have beams + aerodynamic panels)

in both cases the aerodynamics provides 20 panels along the opening and 5 along the rope, while for the winglet are 1 and 5 respectively

so the knots have different coordinates, while I tied structure and aerodynamics with a spline

 

[whaz86]

I have a question about the cord2r command (the main reference system is that of the images placed above)

the command allows me to define a new reference system (indicated here with the apici) using three points: the first I define the origin, with the second direction of the axis z' and with the third one vector which forms with the axis z' the plan x'z'

Therefore, considering the 4 meters long beam and the origin of the primary system in the first node of the beam, using the following 3 points I should correctly define the new reference system; so the axis y' coincides with the direction of the winglet

a[0.0;4000.0;0.0]
b[0.0;4001.0;0.0]
c[1.0;4001.0;0.0]to interpolate use the command spline2

doing so the nastran does not give me errors in f06 but I continue to have the deformed "slegate" of wing and winglet

 

[Onda]

mi scrivi in mp .

 

[ornitorinco91]

Bye. I did a flutter analysis and got the f06,f04, op2 files. Now to see the results on patran where you can upload the .op2 file?