results display problems with patran/nastran 2008

[davide123]

Good evening, everyone.

My name is Marco (although the nickname is davide123) and I am new to this forum; I am preparing a thesis with the help of patran and nastran, both of 2008, but I have some problem to properly turn these two programs. 1) everything begins with the assignment of loads, specific load houses, click analysis and patran generates the .bdf file; then open the screen of nastran, load the file, but under the phrase "md nastran beginnig job ..." appears the following phrase "impossible to find the specified path": Can someone tell me why I'm trying?
2) Despite this, nastran generates the .xdb file or .op2; when I access the results, I have the two screenshots attached to me; as you can see, there are showy white patches on the structure, while instead, not having loaded it, it should look all white; why?

Thank you for your attention and apologize for the trouble.. .

Mar

 

[Onda]

Hello, Marco, welcome.
If you have such a high bond force a load there must be!
pressure, acceleration something is there!
Besides, you move one knot, maybe you're bound to one point?
It also seems to me that you are plotting the results by keeping under geometry. You have to hide it otherwise you don't understand much.
Hi.

 

[davide123]

thanks wave for your prompt response.

I am a novice in the use of these programs then what you see is the only fuselage of the ultrasound that I am trying to design. I previously calculated by hand the binding reactions of the bond, which is an incaster. I placed such values in the program by applying it to the points where the wing attack should be. thanks to the advice to hide geometry, I had not thought about it!
Why do you think you see those white pizzas?

Mar

 

[Onda]

white pizzas are non-scale areas of representation. That's unsolicited.
I didn't understand how you applied loads and constraints. Maybe if you make a pattern on a piece of paper and the scanner is easier to help.
I think you should put the plane on the wings, on the z and apply a gravity.
another z bond put it on the tail plane, to avoid the moment (beaching).
then I recommend you to also bind on x, y in the tail. and put if one part of the wing a bond in x.
In this way the model should be bound isostatic and allow a congruent deformation.
Otherwise, you should do an inertia relief analysis, but that's the system with which the free bodies are analyzed with a balanced force system, but I don't think it's the case for now.

you can also not apply the ties of the wings on a single knot. you have to create a rbe2 that represents the wing attack zone and apply the constraint to the independent node of the rbe2, otherwise you "scratch" the knots as in your case
Hi.

 

[davide123]

Thanks for the answer, I will try to make changes then. instead regarding that message of nastra: "Impossible to find the specified path", what do you recommend to me to do?

Mar