8 votes

Why does the upper wing skin fail in buckling and lower wing skin does not?

In a wing the normal situation is that the aerodynamic force is upwards (resisting gravity). You are right that there is some shear and a fair amount of torsion, but the result is that: the top side ...
NMech's user avatar
  • 24.3k
7 votes
Accepted

Definition of buckling as a sudden deformation

Yes, buckling is a sudden change in shape. A unevenly made column that bows as a result of increasing stress would just experience deformation. Or a metal bar bent by a "strongman." Buckling is ...
Tiger Guy's user avatar
  • 6,783
6 votes

Definition of buckling as a sudden deformation

Defining buckling as "a sudden change of shape" seems to be mixing up cause and effect IMO. What happens is that the load-deflection path of the structure bifurcates when the load reaches a critical ...
alephzero's user avatar
  • 12.5k
5 votes
Accepted

Beam buckling criterion?

Shear buckling of beam web happens when the shear at a section of the beam under consideration surpasses the controlling combination of factored shear. The following three equations are the LFRD ...
kamran's user avatar
  • 22.2k
4 votes

What is meant by "perfect geometry" in the context of Euler buckling?

It means exactly what it says. The geometric tolerances in the beam are exactly zero. The material is perfectly isotropic and homogeneous. The end load is distributed across the surface of the end of ...
alephzero's user avatar
  • 12.5k
4 votes

Buckling vs. Yielding Failure of Columns

The basic Euler buckling formula is unrealistic because it implies perfect geometry and perfect alignment of the loads. Therefore a large empirical safety factor is required. It is also a potentially ...
alephzero's user avatar
  • 12.5k
4 votes
Accepted

Do yielded columns buckle?

When a column is stressed beyond yield, the strain increases rapidly with small changes in stress, at this stage, the stress-strain curve is no longer linear, and the tangent modulus decreases. The ...
r13's user avatar
  • 8,164
3 votes

Definition of buckling as a sudden deformation

Real structures do suffer from buckling. Yes, real structures are never perfect. Columns aren't perfectly vertical, cross-sections aren't perfectly consistent throughout the span, the material isn't ...
Wasabi's user avatar
  • 13.1k
3 votes

Why is buckling said to be independent of material strength?

A column can be considered "failed" if it buckles. The equation for the critical buckling load for a slender column contains the material's elastic modulus but not its yield strength. In this sense, ...
niels nielsen's user avatar
3 votes

Buckling vs. Yielding Failure of Columns

Yes, it is better to design for yield than buckling because Euler buckling is a result of instability as opposed to overloading force. Gamma f is determined from Eurocodes which are from extensive ...
Rhodie's user avatar
  • 974
3 votes
Accepted

Critical Buckling Load for a Spring Supported Bar

To answer the specific question: (a) No, that equation is irrelevant and (b) Yes. see below. The question isn't about Euler buckling. It says the bar is rigid. Euler buckling only applies to a ...
alephzero's user avatar
  • 12.5k
3 votes

Beam buckling criterion?

What you want to look for is Shear buckling or Web buckling. It is quite an advanced subject though. In order to determine mode of failure, critical loads etc, you need to specify explicity the ...
NMech's user avatar
  • 24.3k
3 votes
Accepted

How do I calculate how many newtons a hollow rod can carry without buckling?

For Euler Buckling the critical load is: $$ P_{cr} = \left(\frac{\pi}{K L}\right)^2 E I $$ where: $P_{cr}$ is the critical load $E$ is Young's modulus (for steel assume 200 [GPa]) $I$ is the second ...
NMech's user avatar
  • 24.3k
3 votes
Accepted

What Causes Asymmetrical Buckling in this structure?

First of all, buckling is an instability failure mode. I.e. the structure resists up to a critical load, and beyond that the failure is very rapid. In most textbooks, buckling is considered in single ...
NMech's user avatar
  • 24.3k
2 votes

Possibility of buckling in non-slender member?

It is not necessarily a typo, but you wouldn't normally call a thin walled cylinder 8mm high and 100mm diameter a "pipe". However, the formulas for Euler buckling are most definitely not valid for a ...
alephzero's user avatar
  • 12.5k
2 votes

Can buckling failure at the first critical load be avoided by "instantaneous" loading?

This is just wrong. The notion of a "critical load" in Euler buckling is a very simplified mathematical idealization of the situation. In the real world, buckling behaviour always involved nonlinear ...
alephzero's user avatar
  • 12.5k
2 votes

Methods to Measure Buckling without Expensive Equipment

In principle the axial load in an element is related to its natural frequency. Think of it like a guitar string - increasing the tension in the string raises the pitch (frequency). It may be ...
atom44's user avatar
  • 2,631
2 votes
Accepted

How would I do a buckling analysis with an additional fixed known lateral force?

In your example 2, Nastran is scaling both loads as part of the buckling load. In your first case, you have buckling with $90\times 1 = 90$N axially plus $90\times 1=90$N laterally. In the second, ...
alephzero's user avatar
  • 12.5k
2 votes
Accepted

Why is buckling caused by nonlinear geometry?

The real world doesn't know anything about approximations you make in mathematical models of it. If always behaves in a fully 3-dimensional way. For Euler buckling of a column, you are really ...
alephzero's user avatar
  • 12.5k
2 votes

Why is buckling said to be independent of material strength?

I think that your first link covers it. Stress or strain virus the -strength- of the materiel is not part of the buckling equation. This equation provides the upper limit, it is going to buckle at ...
Ack's user avatar
  • 358
2 votes

Why is local yielding considered the limiting case in context of buckling in Eurocode?

Euler buckling is a perfectly elastic behavior: if a beam buckles, it takes a sinusoidal shape of arbitrary (possibly infinite) amplitude. If you then remove the applied force, the beam will return to ...
Wasabi's user avatar
  • 13.1k
2 votes

Why is local yielding considered the limiting case in context of buckling in Eurocode?

One of the most fundamental principles in the eurocodes is the distinction between the serviceability limit state (SLS) and the ultimate limit state (ULS). An element that has large, visible ...
ingenørd's user avatar
  • 1,288
2 votes

Using modes from linear buckling analysis as imperfections

I briefly glanced this article. Seems interesting but I haven't read it yet - hopefully I'll still be able to help. First, lets say a few words regarding the non-linear buckling analysis. It is ...
Yaniv Ben David's user avatar
2 votes

Why does the upper wing skin fail in buckling and lower wing skin does not?

Wings are designed as a complex structure of spars and ribs, clad with aluminum, titanium, or new composite sheathing, or in the fabric, in the early planes. The Frame has been designed to support all ...
kamran's user avatar
  • 22.2k
2 votes
Accepted

Describing 180 degree arcing/deflection of wire supported vertically at one end

An interesting little problem! I simulated it using what I hope are reasonable values: density=7850; modulus=200e9. The resulting bent wire looked like this: It looks plausible and is a lot less ...
Peter Balch's user avatar
1 vote

Why is buckling said to be independent of material strength?

In this formula for buckling stress (of a long column) we do not observe any strength parameter involved. In this kind of problem the geometry comes to the fore and governs the failure due to buckling ...
MANIMARAN's user avatar
1 vote

Definition of buckling as a sudden deformation

A column or, a bar, even an empty can of soda may have imperfections and or a nonsymmetrical loading and carry a load and deform without buckling. Buckling happens when the load exceeds the critical ...
kamran's user avatar
  • 22.2k
1 vote

Definition of buckling as a sudden deformation

Because it's a failure. Once it starts, it weakens the structure and, assuming the load is consistent, the strength is reduced and it can now buckle easier in a feedback cycle. Longer spans of wood ...
Ack's user avatar
  • 358
1 vote
Accepted

Twist "buckling" critical load

There is no buckling under torsion in a beam, there is lateral web buckling under vertical loads under certain circumstances. A beam under pure torque will gradually twist due to St Venant and ...
kamran's user avatar
  • 22.2k
1 vote
Accepted

For arc-length method in nastran, how to analyse post-buckling behaviour with load decrease

If your model is very symmetrical (e.g. a circular cylinder with an axial compressive load, modeled with a regular grid of elements not an automatically generated irregular grid) you can hit problems ...
alephzero's user avatar
  • 12.5k

Only top scored, non community-wiki answers of a minimum length are eligible