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Questions tagged [buckling]

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11 votes
2 answers
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Buckling: Do buckling mode shapes of n > 1 occur in reality?

In the buckling of columns we know that: $$P = \dfrac{n^2\pi^2EI}{L^2}$$ The smallest value of P occurs when $n=1$ which gives a simple buckling shape (one wave): $$P_{cr} = \dfrac{\pi^2EI}{L^2}$$ ...
pauloz1890's user avatar
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10 votes
8 answers
2k views

Definition of buckling as a sudden deformation

On Wikipedia, buckling is defined as follows: In engineering, buckling is the sudden change in shape of a structural component under load such as the bowing of a column under compression or the ...
S. Rotos's user avatar
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6 votes
2 answers
424 views

Eccentricity for staggered 2x4 wall

I have a staggered 2x4 wall on a 2x6 sill plate as illustrated below (16" on center on each side = 8" on center each stud). The wall is loaded from both sides by floor joists, so I would ...
user2817017's user avatar
4 votes
2 answers
487 views

Beam buckling criterion?

If I have an I beam which I subject to some bending load, how can I calculate when the thinner middle part of the I beam will buckle? I though I could use Euler's critical load formula here, but it's ...
Beacon of Wierd's user avatar
4 votes
2 answers
300 views

Do yielded columns buckle?

A sufficiently slender column will fail under compression below yield stress by bowing, releasing it's axial elastic strain. This is called buckling. Depending on the slenderness of the column, the ...
Abdullah is not an Amalekite's user avatar
4 votes
2 answers
286 views

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

In Eurocode, when use buckling curves to calculate the maximum load that a compressive member can be subjected to before it risks buckling. Buckling curves are based on the Perry-Robertson formula. I'...
S. Rotos's user avatar
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3 votes
1 answer
423 views

How thick does an aluminium vacuum cylinder have to be?

Take a hollow aluminium cylinder with outer radius $r$ and length $h$, capped with two circular endcaps. How thick does the aluminium have to be, that is what is the inner diameter of the cylinder, ...
user1717828's user avatar
3 votes
2 answers
656 views

How to compute core stress in honeycomb structure?

Assume I have a honecomb(sandwich) panel under distributed normal load. Each edge of this panel is simply supported(pinned) as on the picture below: The problem is how to find the core stresses σ-z (...
Eugene's user avatar
  • 63
3 votes
1 answer
310 views

Methods to Measure Buckling without Expensive Equipment

I'm working with some flexures (circularly symmetric tube with pins at the ends). Their bending stiffness matches my FEA. However, I'm concerned that they are buckling, reducing their overall axial ...
user3533030's user avatar
3 votes
0 answers
36 views

How do FE solvers solve the case of panel buckling under pure shear?

How do FE solvers solve the case of panel buckling under pure shear? The main problem is that global matrix of initial stess is singular in that case. One method is to apply some forces that shear is ...
Евгений Павлов's user avatar
3 votes
0 answers
710 views

Column Buckling Boundary Conditions -- Welded Tubing Practical Application?

I'm trying to do some calculations for a personal project. I'm trying to understand column strength / buckling. My questions relate to Effective Length Constant, which is based on Boundary ...
zipzit's user avatar
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2 votes
3 answers
2k views

Buckling vs. Yielding Failure of Columns

As I have been working through examples of construction projects, I've noticed that in nearly every case of a structural column (sample size considers only homogeneous material columns, no composite ...
Richard Bonnardel's user avatar
2 votes
3 answers
795 views

Why is buckling said to be independent of material strength?

In many sources, such as here, it is said that buckling failure is independent of the material's strength. But in many building codes, yield stress of the material is a factor that changes the ...
S. Rotos's user avatar
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2 votes
2 answers
103 views

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

In this question for example (in the first answer) it is said that the Euler critical load formula is unrealistic, because it assumes perfect geometry and perfect alignment of the load. I've found ...
S. Rotos's user avatar
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2 votes
2 answers
383 views

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

how can I calculate how many newtons a 600[mm] long rod with a known yield strength (300 [MPa]), young modulus (190 [GPa]) and hollow (outer diameter = 16[mm], inner diameter = 10[mm]) will carry ...
AnatolianCat's user avatar
2 votes
2 answers
122 views

Using modes from linear buckling analysis as imperfections

I'm reading this article on buckling. It first introduces us to linear buckling analysis, and then mentions that linear analysis can be unrealistic as it doesn't take imperfections into account. Then ...
S. Rotos's user avatar
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2 votes
1 answer
340 views

Twist "buckling" critical load

I have a very long beam which is subjected to a torque (I have the moments and shear forces with respect to X along the beam). I can calculate the critical load when the beam would bend if it was ...
Beacon of Wierd's user avatar
2 votes
0 answers
53 views

Can the critical buckling load from non-linear FE calculation be higher than the one from linear?

Let's consider a FE buckling calculation without plasticity. Is there theoretically any chance that the non-linear analysis will give a higher buckling load than the linear one?
G.David's user avatar
  • 53
1 vote
3 answers
2k views

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

I am aware of the fact that the buckling is mainly caused in the regions of the specimen which are in compression. But the wing skin doesn't take any axial loads and is used to resist shear, atleast ...
Rameez Ul Haq's user avatar
1 vote
1 answer
170 views

What Causes Asymmetrical Buckling in this structure?

I've been playing around with structural modelling on the SkyCiv platform and have created this structure, related to a project I am working on to educate myself. It is 2m wide, 3m long and 1.5m high ...
Steve Feeds's user avatar
1 vote
2 answers
183 views

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

Previously, I was told by someone I trust well that a column can avoid buckling at the first critical load by applying the load "instantaneously" with a magnitude between the first and second critical ...
mb106's user avatar
  • 11
1 vote
1 answer
2k views

Critical Buckling Load for a Spring Supported Bar

The above is a past exam question from an introductory structural analysis course, one in which although we have studied the Euler buckling load equation, we have just been given parameters for the ...
user120568's user avatar
1 vote
1 answer
90 views

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

I am using Nastran for buckling analysis, and I'm new to all of this so please bear with me. For a linear buckling analysis, I understand that you must first apply any compressive load in the static ...
Jeroen's user avatar
  • 67
1 vote
1 answer
177 views

Possibility of buckling in non-slender member?

The above diagram is misleading. In reality, both the length and thickness are equal to 8mm. As this is from a past paper (one notorious for awkward questions), I'm not sure if it's a typo (an 8m ...
user120568's user avatar
1 vote
5 answers
75 views

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

I am trying to understand how to describe and calculate the shape a length of piano wire makes from its own weight when supported vertically at only one end. Is it a catenary or a parabola? ...
Rafe Copeland's user avatar
1 vote
1 answer
115 views

Stability of solid rectangular wood member

I'm reading about buckling of timber members from Eurocode 5: Design of timber structures part 1. Formula 6.30 gives the relative slenderness of a member: $$\lambda_{rel.m} = \sqrt{\frac{f_{m,k}}{\...
S. Rotos's user avatar
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1 vote
1 answer
461 views

Shear capacity according to eurocode , when to use which equation

I am looking at eurocode to calculate shear capacity, and under section "6.2.6 Shear", there are two different shear checks: Eq 6.18 Eq 6.19 When there is no torsion we can use equation 6....
greatoak763's user avatar
1 vote
2 answers
124 views

Can a thicker model have a lower critical buckling load?

I perform a linear buckling analysis for two similar geometries, where one model has thickness t = 0.01 m, and the other has thickness t = 0.035 m. Otherwise everything is exactly the same. The ...
Material scientist's user avatar
1 vote
1 answer
736 views

unbraced length of the compression portion of a long member

I am designing a truss. the bottom chord in the first two panels at each end or at the supports are in compression and the rest of the bottom chord is in tension. there is no lateral bracing along the ...
DDD's user avatar
  • 11
1 vote
3 answers
637 views

Buckling of Parallel rods

I am trying to calculate critical force $P$, if two rods (same diameter and length - rigid fiberglass sandwiched on two steel plates) are parallel to each other. $$ P = \frac{\pi^2 EI}{(KL)^2} $$ I ...
The_Engineer's user avatar
1 vote
1 answer
350 views

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

I am currently trying to model the buckling behaviour of a cylinder using sol 400 nonlinear static analysis using Nastran. I am using the arc-length (modified Riks) method as apparently it can ...
Jeroen's user avatar
  • 67
1 vote
1 answer
271 views

Simple steel column buckling calc - where am I going wrong? (Eurocode)

I'm trying to follow an example of this, but I get a wildly different answer than expected and I can't see where I'm going wrong. The example I've got, is for a 2.8 m steel column (RHS 150 x 100 x ...
Stilez's user avatar
  • 571
1 vote
1 answer
215 views

2D Solid - Axisimmetric - Missing properties and material

Goodmorning, I'm trying to understand how 2D solid elements work. I want to study the local buckling of a simple aluminium pipe with thin walls. From what I understood, I can use 2D solid elements ...
gbos's user avatar
  • 111
1 vote
0 answers
74 views

Do these linear vs nonlinear buckling plots make sense?

I am doing linear buckling analyses (where everything is linear), and nonlinear buckling analyses where you have nonlinear geometry enabled and nonlinear material behavior (hyperelastic material). ...
Material scientist's user avatar
1 vote
0 answers
23 views

Why do we need to have perturbation in our system to do buckling analysis? [closed]

Do we need it for both linear and nonlinear system?
curiousone's user avatar
1 vote
0 answers
45 views

(Follow up) Can a thicker model giver a lower critical buckling load?

I present three seperate models with thickness of t = 0.005m, 0.01m and 0.025m respectively, all have a forced displacement of -0.01m in the x-direction, and fixed on the other end. As you can see the ...
Material scientist's user avatar
1 vote
0 answers
30 views

How is a linear buckling test supposed to look like?

If I had a cube like object; would this be a good way to set up a linear buckling analysis? https://i.sstatic.net/Wqphm.jpg And no other forces or boundary conditions
Material scientist's user avatar
1 vote
0 answers
103 views

How to calculate how much compression is needed for a spring to buckle

First off; School was many years ago and I know little of the mathematics behind all the physics and engineering stuff. So if you have an answer, please explain it like I'm 5? The goal: I aim to be ...
qwelyt's user avatar
  • 111
1 vote
1 answer
81 views

Interaction of buckling modes

I'm reading this paper on structural members subject to both bending and compression. In the first paragraph, in context of the equations 6.61 and 6.62, it is said: The second two terms are modified ...
S. Rotos's user avatar
  • 2,259
1 vote
2 answers
590 views

Buckling of a cantilever with midway support

I'm trying to understand the implications for buckling and column sizing in the drawings below. A 3000mm 120x60 RHS steel column supports a 350mm horizontal steel beam. The column base and right side ...
Stilez's user avatar
  • 571
0 votes
1 answer
58 views

Minimal width of a carbon fiber shell to hold a flying airship

In Aves Æternæ: Building Perpetual Flying Machines you can find the specs for an airship with a rigid carbon fiber shell. It would be around 4m long and 2m wide and high, weigh around 10 kg empty (0 ...
alexfernandez's user avatar
0 votes
2 answers
200 views

maximum allowed load [closed]

I have the following problem E= 210 MPa d = 40 mm n = 20 y = 1.5 a =1 calculate the maximum allowed load for the system I am confused on how to solve the problem, I really need advice.
August Jelemson's user avatar
0 votes
1 answer
136 views

Why is buckling caused by nonlinear geometry?

I've been reading the Comsol post on geometric nonlinearity. The article introduces situations where the small angle approximation and linear analysis of structures gives inaccurate results. For ...
S. Rotos's user avatar
  • 2,259
0 votes
3 answers
3k views

Inertia Relief and Buckling SOL105 in Nastran

Has anyone ever tried running buckling simulations in Nastran where inertia relief is invoked? I am just using a simple plate and I am getting "funny" modes (unrealistically low eigenvalues which ...
Ma0's user avatar
  • 103
0 votes
2 answers
36 views

Can a buckling steel column fracture on multiple points?

When a column buckles, then yields, and finally fractures fractures, along the most stressed point, this will initially reduce the axial and bending strains along other points. The apparent conclusion ...
Abdullah is not an Amalekite's user avatar
0 votes
1 answer
49 views

How to calculate maximum buckling load for hydrofoil strut?

I am a hobbyist and in the process of designing a human-powered hydrofoil (see Hydroped for reference) I'm kind of stuck in the calculation of the the maximum buckling load for a strut. The strut is ...
marco trevi's user avatar
0 votes
1 answer
56 views

What is the critical buckling force needed to be applied on a system of made out of two parts?

What is the critical buckling force needed to be applied on a system of made out of two parts? The parts of the system are as depicted in the picture: incompressible elastic beam - on top ...
Avishai Barnoy's user avatar
0 votes
2 answers
117 views

How to find the tension in wires before a column buckles

I already have the solution for this problem, I just need some explanation about a certain part. Can someone please explain the highlighted section, how do I obtain the tension formula used here?
CountDOOKU's user avatar
0 votes
1 answer
107 views

Why isn't lateral torsional buckling of rectangular timber members dependent on torsional stiffness?

I'm reading about buckling of timber members from Eurocode 5: Design of timber structures part 1. Section 6.3.3 gives instructions to check the stability of beams subject to compression, bending or ...
S. Rotos's user avatar
  • 2,259
0 votes
2 answers
776 views

Hollow Steel Tubing: Critical Load for Sidewall Buckling

I'm looking to construct a something with hollow steel tubing (e.g. 10ga 2"x3" rectangular tubing) suspended horizontally welded to an outer frame on both sides. I've already calculated the ...
iAdjunct's user avatar
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