Questions tagged [buckling]

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11 votes
2 answers
5k views

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): $$P_{cr} = \dfrac{\pi^2EI}{L^2}$$ ...
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9 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 ...
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6 votes
2 answers
296 views

Eccentricity for staggered 2x4 wal

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 ...
4 votes
2 answers
156 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 ...
4 votes
2 answers
173 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'...
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3 votes
2 answers
151 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 ...
  • 156
3 votes
1 answer
395 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, ...
3 votes
1 answer
287 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 ...
3 votes
0 answers
35 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 ...
3 votes
0 answers
332 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 ...
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3 votes
2 answers
280 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 (...
  • 63
2 votes
3 answers
1k 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 ...
2 votes
2 answers
86 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 ...
  • 2,167
2 votes
2 answers
154 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 ...
2 votes
2 answers
78 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 ...
  • 2,167
2 votes
1 answer
346 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 ...
  • 21
2 votes
1 answer
229 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 ...
2 votes
0 answers
35 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?
  • 53
1 vote
3 answers
1k 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 ...
1 vote
3 answers
306 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 ...
  • 2,167
1 vote
1 answer
108 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 ...
1 vote
2 answers
158 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 ...
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1 vote
1 answer
1k 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 ...
1 vote
1 answer
47 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 ...
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1 vote
1 answer
155 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 ...
1 vote
1 answer
109 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}}{\...
  • 2,167
1 vote
1 answer
64 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....
1 vote
2 answers
75 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 ...
1 vote
3 answers
314 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 ...
1 vote
1 answer
189 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 ...
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1 vote
1 answer
142 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 ...
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1 vote
1 answer
138 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 ...
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1 vote
0 answers
55 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). ...
1 vote
0 answers
21 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?
1 vote
0 answers
41 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 ...
1 vote
0 answers
29 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://imgur.com/a/ltMDTlT And no other forces or boundary conditions
1 vote
0 answers
52 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 ...
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1 vote
0 answers
45 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 ...
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1 vote
0 answers
58 views

Buckling of composite plates help

I am trying to write code for the buckling of composite plates using the Ritz approximation but I can't understand something. According to Reddy (Mechanics of laminated composites), this is the ...
1 vote
2 answers
551 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 ...
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0 votes
2 answers
84 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.
0 votes
1 answer
92 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 ...
  • 2,167
0 votes
3 answers
2k 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 ...
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0 votes
2 answers
39 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?
0 votes
1 answer
57 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 ...
  • 2,167
0 votes
2 answers
455 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 ...
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0 votes
1 answer
84 views

Stress concentrations around rivets in compression

The stress concetration factor for an unfilled hole is around 3, but it decreases when a rivet is present. What factor can we expect for a hole with a rivet in it in compression?
  • 1
0 votes
1 answer
168 views

Calculation of critical column buckling load using Johnson's formula, but with eccentricity?

I've got partial answers but nothing comprehensive found online - most online resources focus on Euler's buckling formula which isn't appropriate for shorter columns. Data I have collected: Column is ...
  • 581
0 votes
0 answers
50 views

Why does figure 2 and 6 deform differently from the other shapes?

I am doing a linear buckling analysis on all the structures you see below, they are subjected to compression load in the x-axis as indicated by the arrow. You can see all structures beside 2 and 6 ...
0 votes
0 answers
29 views

How do I find the buckling strength?

I am running something called cell periodicity study in comsol, which finds the material properties of a model. It is done by applying a uniaxial compression load, and performing a nonlinear buckling ...