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Questions tagged [structural-beam]

A structural element whose length greatly exceeds both its width and height, which are of the same order of magnitude.

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Is the shear stiffness of a helical spring for bending negligible?

I want to model a helical spring by beam theory. Lets call $d$ the stock wire diameter and $D=2r$ the the helix radius (see picture below). For example: The axial stretch stiffness is given as here. ...
Pepe's user avatar
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Why does a cantilever beam bend instead of shearing when a point load is applied?

I have just learnt about cantilever beams and that they are free on one end and supported on the other. In my class, my teacher showed an example of when we apply a point load at the end of a ...
Amrit Sanjeev's user avatar
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Beam splitter using a lazer to do the splitting

My title may be misleading, and my question is definatly amateur. I would like to split a beam of light, with a second beam. I suspect this may not be possible (or only possible with large amounts of ...
Robert Diamond's user avatar
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Transfer and distribution of forces in hybrid structure

It's a simple but curious question. For an object made of reinforced concrete, it is said that concrete mainly resists compression force and reinforcement mainly resists tensile force. Whether it's ...
NOH WHIREA's user avatar
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Calculate bending moment for cantilever with uniformly distributed load

I am trying to understand how to calculate the bending moment for a cantilever with a uniformly distributed load so that I can build an equation of moments, as shown in this example: I tried ...
eheshing's user avatar
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Moment of inertia of a cantilever beam [closed]

As part of a project, I'm calculating deflection of a cantilever beam, something like the image below where the beam bends due to a load. To do so requires its moment of inertia, and I'm thinking of ...
Rena W's user avatar
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Why does the beam splitter create superposition?

Why does the beam splitter create superposition ? Ok, in a double slit you have 2 holes in a wall, and thus there are 2 ways through which the particle to go. But in a beam splitter where are those 2 ...
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Elasticity and Hooke's law: who is applying the force?

I am currently studying longitudinal vibrations in an elastic beam. However, I am struggling a bit because it is the first time I have done continuum mechanics. More specifically, when isolating an ...
hugopb82's user avatar
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Derivation of equation for period of cantilever beam when the distance between the point at which a mass is attached and the pivot changes

I am a high school student writing a research paper on cantilever beams. I am investigating the relationship between the distance at which a fixed mass is placed on the beam and the time period of its ...
Aaditya's user avatar
4 votes
1 answer
440 views

Computing the strain in a cantilever beam under a known deflection

I intend to use a cantilever beam to calibrate a strain gauge, in a setup similar to the picture. My idea is to introduce a small known vertical displacement $\delta$ on one side of the cantilever ...
user386164's user avatar
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Why is paper inelastic but flexible?

Recently I have been studying solid structural mechanics, and one of the points I find really confusing is how elasticity and flexibility are closely intertwined. Consider an Euler-Bernoulli beam, for ...
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Huygens-Fresnel integral and Rayleigh integral

While working with the Huygens-Fresnel integral, I learned about the Rayleigh integral again, and I can't tell where they apply and whether they can be replaced equivalently. Also, in terms of ...
Matthias's user avatar
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About EBW (Electron Beam Welding) [closed]

I'm an electron beam welding process engineer. We use vacuum chambers to produce close tolerance welds for the aerospace industry. The vacuum chambers are pulled down by cryogenic pumps on the newest ...
erroRs_'s user avatar
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FFT plot not aligning with lower natural frequencies

I have a cantilever beam with gapped springs on top and bottom and an impulse is given at the free end initially. I modelled it using finite element method with 30 elements. The beam then oscillates ...
john wick's user avatar
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Is Euler–Bernoulli beam theory still correct for non-constant (but continuous) beam cross-section?

How can I use Euler–Bernoulli beam theory for non-constant beam cross-section ? The beam is modeled as a continuous cone of known inner and outer diameters (both a function of $x$ the distance from ...
t9dupuy's user avatar
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Strength Calculation of a Simply Supported 3D rectangular beam Under Loading As Shown In Image Attached

For a 2D and 3D circular beam we can easily calculate the strength of beam and reactions using beam theory. The same can be used for 2D rectangular plate. Also for a 3D rectangular plate with uniform ...
Sandip.G's user avatar
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How to find Shear Force and Bending Moment in Finite Element Method for a cantilever beam with many elements

I have a cantilever beam with lots of elements. I am trying to find the sheer force and bending moment diagrams of the beam. EVERY SINGLE TUTORIAL AND EXAMPLE I SAW ONLINE SHOWS HOW TO DO IT FOR A ...
john wick's user avatar
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Transverse Vibrations of a Cantilever beam. Why does the % change in nth natural frequency increases with n in this case?

This is the problem in detail I have a cantilever beam. Now I am making it stand upright and adding water for different heights of SUBMERGENCE I am doing this by adding an ADDED MASS term from the ...
john wick's user avatar
1 vote
2 answers
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Why is the strain independent of the type of material (in beam bending)?

When a beam is bended, the strain that is produced above and below the neutral axis is proportional to the curvature of the beam and varies linearly with the distance from the neutral axis. But why is ...
user134613's user avatar
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Deriving an equation for the SHM of a cantilever beam with a mass attached at the free end

I'm a high school student doing a research paper on the vibration of cantilever beams. Specifically, I am investigating the relationship between the mass on a cantilever beam and the time period of ...
Emp1's user avatar
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If the range of a laser depends on its crossection perimeter does it mean that a wider beam would reach much longer distances?

If the range of a laser depends on its crossection perimeter does it mean that a wider beam would reach much longer distances? Let pressume that we can construct a 1m wide laser beam and as we know ...
Krešimir Bradvica's user avatar
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Doubt in derivation of bending of beam, It's about derivatives and intergration

Radius of curvature of the beam in above picture is given as: $$ \frac{1}{R} = \frac{d^2 y}{dx^2}$$ Please help me two points used as steps of a derivation in my book: How was the radius of ...
Sai 's user avatar
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Why two wires are used in railway overhead equipment? [closed]

While watching the train video's I came across this overhead wires. After searching on internet I found that both catenary and contact wires carry same voltage and connected by vertical wires called ...
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Deformation of gradually applied load vs impact loads?

When a load P is applied gradually on an object, the work done on it is the average of the initial and final loads, which is generally P/2 multiplied by the deflection Δ1. In the case of impact load, ...
Adarsh's user avatar
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2 votes
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Inconsistent units in modal analysis of vibrating beam

(read the last sentence for the actual question). Consider an elastically suspended solid body from a massless cantilever beam The equations of motion of such a system are $$\begin{bmatrix}m\\ & ...
John Alexiou's user avatar
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Do inertia affect stiffness matrix of beam?

Refering to a pdf I uploaded at here. Why does these stiffness matrix displacement do not need to consider the inertia (determines the shape of cross-sectional area of each element) ? I have always ...
catherine tan's user avatar
5 votes
1 answer
771 views

An intuitive reason for the fourth derivative in the beam equation?

The appearance of the second derivative (or Laplacian in higher dimensions) in the diffusion equation ($u_t=u_{xx}$) and the wave equation ($u_{tt}=u_{xx}$) seems intuitive to me. The quantity simply ...
FusRoDah's user avatar
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The state of a Stress element isolated from a beam

Consider a beam subjected to an arbitrary loading, where the loads are only present in the plane of bending. The x-y plane is the plane of bending. If I take a stress element in the beam, there will ...
Harshit Rajput's user avatar
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Twisting Solid Steel Bar - Annealed, Hardened or Doesn't mater? [closed]

Workshop project underway... Been decades since I was in a physics class. Building something out of steel - options are mild steel 1018 and alloy steel 4140 that can be hardened by heat treatment. ...
speld_rwong's user avatar
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How a fixed support which allows lateral contraction and expansion will look like?

I stumbled upon an exercise problem wherein it was asked to calculate the change in lateral dimensions of a bar fixed between two immovable supports, when temperature of the bar is increased by $\...
Harshit Rajput's user avatar
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941 views

Stiffness of a Cantilever Beam

I was wondering that for a Cantilever beam subjected to point load at extreme end. Does the stiffness goes on changing as the deflection of free end changes? Logically it should provide more ...
AJAY SARAF's user avatar
1 vote
1 answer
37 views

Would bolting four 3" square tubes to an existing 3" square tube (one per side) increase rigidity? [closed]

I had a pier fabricated for my telescope consisting of a 1/4" steel plate, 10" diameter, bolted to a concrete pad. A 3" by 34" square steel tube is welded to the base plate and ...
Mike S's user avatar
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Can I approximate an electron beam in the air to a Gaussian beam?

We have used an electron beam (with energy of 6 MeV, used for treatment of cancer patients) and calculated the received dosage. The experiment was set up with a stationary sensor at length ...
kosta194's user avatar
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How does the load on the tip a cantilever affect how long it continues vibrating after release?

I'm considering a situation in which a load is applied to the tip of a cantilever. After the release of the load, the cantilever oscillates, but due to an energy loss to the environment (which I think ...
Raen's user avatar
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Derivation of dynamic nonlinear equation of motion of cantilever beam

Is it possible to derive the EOM of an inextensible cantilever beam without using any kind of variational principle I mean is it possible to derive it from Newton's law only? Note: of course This ...
T H's user avatar
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Difference between bending equation of cantilever beam and dynamic equation of motion

What is the difference between Bending Equation of cantilever beam and dynamic equation of cantilever beam? Is it possible to derive one from the other?
T H's user avatar
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Angular damping on a cable segment caused by internal friction

I'm using a physics engine to simulate a cable made of cylinder-shaped segments connected by ball socket constraints. My understanding is there will be some angular damping on the segments cause the ...
Lazy Waves's user avatar
1 vote
2 answers
44 views

What is the mathematical description of a point torque (or point couple) singularity?

Suppose that a concentrated (point) force is exerted at the origin of a 3D dimensional space along the direction $\boldsymbol{e}$. Mathematically, this could be prescribed in terms of a delta Dirac ...
Siegfriedenberghofen's user avatar
1 vote
2 answers
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Will a platform only supported by a column in the center fall? (Excluding weather)

My friend told me that without wind, a building with a platform that only has a column supporting it would be balanced and not fall, given that there is no wind. I said that the platform would fall ...
Luke S's user avatar
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Adding tension to a model of a Timoshenko beam?

I am interested in modeling a Timoshenko beam. However, I would also like to add tension to the beam so that it can vibrate like a string as well as a beam. The Timoshenko beam is described at that ...
mike's user avatar
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1 answer
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How is this basic equation of a Timoshenko beam derived?

I am trying to learn how to model a Timoshenko beam which is described here: https://en.wikipedia.org/wiki/Timoshenko%E2%80%93Ehrenfest_beam_theory There are a few things I can't understand but the ...
mike's user avatar
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642 views

Why is shear force half the total force?

When applying a perpendicular force to a beam which is fixed on either side then the shear force is given by $V=\frac12 F$. My intuition says that this is because the force $F$ is distributed over two ...
Angelorf's user avatar
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Catenary shape of transmission lines

When flexible metal transmission lines are hung between two poles, the shape they assume to minimize the action of gravitational and tensile forces is a called a catenary. While assuming that shape, ...
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1 vote
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Swords and wing flutter

In order to retain structural integrity it is understandable that a sword has to be flexible enough to be able to absorb impact without shattering and rigid enough to not be bent due to it. Is this ...
kbakshi314's user avatar
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1 vote
1 answer
249 views

Simple cantilever beam deflection - what is the simplest way to add a damper?

I am looking at a simple cantilever beam deflection: I understand the general expression for deflection/force would be: $y_s = \frac{Fx_s^3}{3EI}$ $F_p = \frac{3y_sEI}{x_s^3}$ If you were going to ...
mike's user avatar
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1 vote
3 answers
120 views

Why buckling is described by the maths of the harmonic oscillator?

Is this a coincidence or there is a more deep connection between the notion of the harmonic oscillator and the notion of buckling?
veronika's user avatar
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2 votes
1 answer
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How do I account for damping on structural vibrations?

I want to know what terms to add to the differential equation for structural vibrations to account for structural damping. Not external damping, but internal damping. I consider the transfer of energy ...
John Alexiou's user avatar
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9 votes
3 answers
766 views

Tower of building blocks

Why does a tower of building blocks (cubes) fall? Theoretically, as long as the center-of-mass is above the blocks' bottom faces, and as long as one does not shake the tower too much, it should not ...
Roger V.'s user avatar
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Shear stresses in a rectangular beam

To find the shear stress at point A in the beam above using the equation τ=VQ/(It), how do you decide which value of thickness to use? Is it correct to use a value of 100 mm because the cut segment at ...
Andy's user avatar
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Why does the LASER beam quality factor (M^2) use squared value?

Why does the LASER beam quality factor (M^2) use squared value? Why not using just M? i.e., Why define beam quality factor as $M^2 = \frac{BPP_{Real}}{BPP_{fundamental}}$ not $M = \frac{BPP_{Real}}{...
Minhyeok Kim's user avatar