Thank you for all your answers. I am prone to think that things would happen as rb1957 describes. "A (notched) will fail at a slightly smaller load than B".
Dougt115 and tbuelna: I do not think it is as simple as you describe it. If we just applied the Kt factor from Peterson to the nominal...
Good morning/evening, Sirs
I am thinking of the effect of local stress concentrations on the strength of the metal parts. In order to clarify my ideas, I have thought of a simple test:
Let's imagine we have a test specimen A (made of aluminium, or steel) with a rectangular section of width "a"...
@ RPstress: you say you are curious to know from anyone working on flap tracks in the last few years whether low alloy steel is still being used.
In one of the last Airbus aircrafts, the flap tracks are machined from titanium.
Firts of all, I thank you all for answering.
Please, let me sumarise what I have understood about the methods exposed here (see attached file). Please, correct me if I am wrong.
- edbgtr suggests a cantilever model with concentrated loads (model A in the attached sketch)
- rb1957 proposes a...
Hi rb1957, thanky ou for your answer.
Actually what you say was my first impression too. But then I found in Flabel (Chapter 5, page 321 and 322): "For higher loads applications, a tension clip can be safely beefed up by using a radius block..." (it doesn't say how the filler is helping though)...
Hello,
I am updating an old calculation with new loads.
It is a channel type tension fitting analysis based on Lockheed 88a. In the old calculation, in order to improve the RF, a filler was added.
The way the RF was calculated was using an *equivalent end pad thickness*:
t_eq = SQRT (t_pad^2 +...
Hello,
I have never used shell elements in Marc before. I would appreciete it very much if you could answer these two questions:
1. Have the shell elements stiffness in the rotation normal to the shell plane?
2. If not, how can this problem be fixed?
Thanks in advance.
Hello,
Lets say that I have a F.E. model of my structure. the structure is made of a material whose ultimate tension allowable stress is Ftu.
I perform an analysis for an ultimate load case and I read the maximum stress Smax.
- If the analysis is LINEAR I would define the reserve factor like...
Hello,
* Problem:
lets say that we have 2 Al plates (0.2 inches thick) joined by means of several Ti fasteners. At Ultimate Load, the load of one of the fasteners is higher than the Fbru (ultimate bearing allowable).
* Questions:
1. Is it possible to consider that this fastener can take load...
Thomas, your explanation is very clear and useful, thank you.
Kellnerp, thanks again for your posts. I misundestood your question about "how close the solutions are". In fact the first eigenvalues are quite close (0.987; 1.033; 1.042; 1.083).
My model is a section of a Aluminium longeron. It...
kellnerp, the shape of the buckled structure resulting from the linear buckling eigenvalue solution is the same as the one from the nonlinear static solution (of course in the nonlinear one appart from the bucking there are other deformations in other zones that have nothing to do with he...
Thank you both for the replies.
drk186, sol 106 is the nonlinear or linear static. And, please correct me if I´m worng, but I think that if I don´t use the PARAM,BUCKLING, the SOL 106 doesn´t calculate any eigenvalue. Hence, my problem is how can I tell if certain part of the structure has...
Hello
I have a FE model with non linear material properties.
If I run a SOL 106, will I be able to see the buckling modes?
Tips:
1. There is also a method (that implies the use of PARAM,BUCKLING among other things) to calculate the buckling modes. But I´m not talking about that, just about a...
Hi edbgtr,
if I didn't misunderstood you, you want to study stability of the web of a bending beam.
If so, I would suggest to consider the next:
- if the Web is not high and thin: beam bending theory: no buckling.
- if the Web is high and thin: diagonal tension
When a beam is submmited to...
Hi rb1957,
IMHO, Von Mises is not exactly a "just a formulae to combine together stresses to give you a scalar quantity to determine a failure index". As far as I know, the Von Mises value is calculated in order to determine wether a multiaxially loaded material has yielded or not. How?: Von...
Many thanks for your opinions, gentlemen.
Yes, I am using someone else’s model. The skins are plates: the FEM “experts” argue that it is in order to avoid too-many-DOF problems, and that the skin and stringers actually do have that bending stiffness: not a too big stiffness, but they say that...
Thank you both for the reply.
In order to clarify the problem lets assume a ref. system : x-> chord wise; y-> span wise; z-> normal. Then xy is the skin plane.
Crackman, when you say “there can be an out of plane moment” should I understand:
-1. “there can be an in plane moment (Mx) due to...
Thank you for your reply. I beg your pardon for the vagueness of my explanation: instead of “vertical” load I should have said “out-of-plane” load.
The load that worries me is not the end axial load of the Bar elements of the stringer, but the load out-of-plane (shear force of the Bar element...
This is my first post: hello everybody.
I am working on the skin (aluminium) of a wing. I am studying the stringers run out. Between the end of the stringer and the supporting rib there is a distance of about 1.6 inches. This region of the skin must carry the vertical shear load of the stringer...
