# What is Beam: Definition and 1000 Discussions

An I-beam, also known as H-beam (for universal column, UC), w-beam (for "wide flange"), universal beam (UB), rolled steel joist (RSJ), or double-T (especially in Polish, Bulgarian, Spanish, Italian and German), is a beam with an I or H-shaped cross-section. The horizontal elements of the I are flanges, and the vertical element is the "web". I-beams are usually made of structural steel and are used in construction and civil engineering.
The web resists shear forces, while the flanges resist most of the bending moment experienced by the beam. The Euler–Bernoulli beam equation shows that the I-shaped section is a very efficient form for carrying both bending and shear loads in the plane of the web. On the other hand, the cross-section has a reduced capacity in the transverse direction, and is also inefficient in carrying torsion, for which hollow structural sections are often preferred.

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1. ### B Pinched plasma inside a neutral beam injector

Let me start this off with saying I am just a uneducated idiot, But after reading about Zap Energies sheared flow pinch reactor I was wondering if you could use a similar concept in a neutral beam injector? Like could you first compress and heat the plasma inside of a NBI using a pinch, then...
2. ### Beam deflection and curvature radius formula doubts

Hi, I am working with leaf springs and studying the derivation of the formula for the deflection of such a structure. The derivation is shown here: My only doubt is how to obtain the following formula: $$\delta=\frac{L^{2}}{8R}$$ where: ##\delta## - deflection, ##L## - length of the beam...
3. ### Concave mirror reflecting a point lamp, that create a wider beam

I've look if there was any way to get the "image size" or a ratio to use the Mirror Equation to find the focal length, but nothing. I think it's base on some geometry, but I don't see the relation.
4. ### Trailer Frame Beam Design

I'm building an aluminum tandem axle (7k total capacity) trailer. Boat (18'/1300#) on the rear and a Ryker Can Am 3 wheel (750#) on the front. It's a 23'-6" x 6'-8" bed. Max live load will be approx 2250#. 900# frame weight. 230# axles. I'm testing beam sizes with online calculators and need...
5. ### Free Beam moment problem

Hello all, I'm trying to understand the maximum moment on a free beam. Consider a tail sitter drone that is simplified into being a beam with two motors fitted with propellers on the end of the beam (see the photo below), let the payload be estimated as two, 2 newton loads going downwards. If...
6. ### Box Beam stress problem with welding

Hello All, I'm trying to figure out how to strengthen a box beam that's been welded to another box beam. In the photo on the left is 2 beams welded to each other, they are 2x1" Aluminum 6061-T6, with a 1/8" wall thickness. The yellow lines indicate the location of the weld. A force of 216 lbs is...
7. ### I Mach-Zehnder interferometer, but with an entangled beam?

Hello, The Mach-Zehnder interferometer makes it possible to highlight the corpuscular and undulatory aspect of light, (in particular using single photons). By using the "continuous" beam from a coherent source, one is able to visualize directly on two screens E1 and E2, an interference pattern...
8. ### I May I treat the light from a star as a light beam?

Hi. I am studying the wavefront evolution of light from a star. In the papers I have read, the star is often treated as a point source and the light is approximated as a line (geodesics), but this approximation is not very useful when I study the wavefront evolution, so I want to extend the...
9. ### Engineering Calculating shear center for a "skewed" I beam

Here is the diagram of the cs: As a premise I must say that this topic(shear center and shear flow distributions) is still very hectic in my mind; I aim to clarify it a bit by asking you guys this :) So, in order to identify the SC location, I must compute at what distance a point shear force...
10. ### Sign hanging from massless beam attached to hinge supported by string

Attempted creating equations for zeros of torque and components of forces in x and y as seen in picture. Got lost with having only variables and the d & 2L for the length of the beam. Not sure how to do the question with two points of contact between the beam and the sign. Is the center center...
11. ### A Fast electrons passing a beam of slow electrons at a right angle

I'm wondering what happens when fast electrons (100 - 300 keV) interact with a beam (diameter 1 to 10 μm) of slower electrons (1 to 10 keV), which is at right angles to the trajectories of the fast electrons. The beam of slower electrons is relatively dense with 1 to 10 electrons per μm line...
12. ### Engineering Why was the thickness of the beam included in calculating this moment?

Hi all, Why was the thickness of the beam considered when moment was being calculated and why was the horizontal component of the 600 N force used in calculating the moment? That part is unclear to me. Please explain it. Am I looking for the logic behind using the horizontal comp. and the...

34. ### B Beam of air: Extending the range of a fan

If one Googles for "laminar flow nozzle", one finds many interesting tutorials on creating a nozzle for a laminar water jet; a stream of water that remains coherent over a long distance without breaking up. These typically consist of a large-diameter tube with regions inside (like sponges and...
35. ### Leaf Spring Deflection: Calculating Force & Displacement

Hi, I'm trying to calculate the deflection of a leaf spring. I've found several formulas but the one I'm currently using looks like this: $$f=k \frac{F L^{3}}{6EI}$$ where: ##k## - coefficient depending on the way leaves change their shape in the width direction (in my case it's ##1## because...
36. ### Magnitude and average value of energy intensity of light beam

I tried using the equations above, but I wasn't really able to come up with an intuitive explanation. From my understanding, the electric field vector only varies in the x-y plane while the magnetic field vector only varies in the z-y plane. Also, both vary sinusoidally and both reach extrema...
37. ### I Base Motion and Vertical Beam - Basic Reaction Forces?

So I am trying to understand how to estimate the amount of deflection [D] the vertical beam shown above would experience if the base it is attached to is accelerating at a constant acceleration [a] of 9.81 m/s. I assume the Force [F] would be equal to weight of the vertical beam (mass x...
38. ### A Optimum profile of light pipe exit for narrow beam angle

I am trying to design an acrylic light pipe that has a 3W power red LED input with 60 degree beam angle. I need a reasonably collimated exit light beam or at least a narrow angle output. What I'd like to know is - what is the optimum shape of the exit end of the light pipe to produce the...
39. ### Beam current of positrons and electrons

a) My idea is: 1. Find the energy created by annihilation process, which is ##E=2mc^2## where m is the mass of electron 2. Find the wavelength of photon by using formula E = hf 3. Find the speed of positron by using the formula of de broglie wavelength 4. Find the p.d by using conservation of...
40. ### Approach analytical calculation for a beam frame

Hi all, Currently I am working on a home-project, making a trike. Now just for fun and because I like to calculate things, I calculated the deflection of a frame with a load. The frame is shown in the picture below, I added the force for clarity. With my analytical calculation I found a...
41. ### Engineering Diagram of a beam with distributed load - SOLVED

Hi guys, I'm wasting much time on this problem but still can't manage to get to a solution; I'll attach my attempt below. I started with drawing the FBD of the beam "sectioned" at point C, in order to find an expression for the internal shear force at that point and then equal that to zero...
42. ### A Weird pattern for a laser beam spot

Hello! I am trying to measure the gaussian profile of a laser beam, which is supposed to be T00. The profile shown in the specifications looks very Gaussian, and the laser is brand new. I am using this camera and I am using 2 of these wedges to guide the laser beam into the camera (mainly to...
43. ### Engineering Find the support reactions on a beam

Hello! in this good afternoon ;). I need some help for this beam and his support reactions. The problem it is done, but my result its different from the teacher`s result. I'm sure my answer is correct, as even the "SkyCivbeam" online software also gives the same results. it appears that the...
44. ### Equivalent system (force+couple moment) of a loaded beam

Hi guys, I don't really know how to cope with this problem, maybe just because I can't properly understand the data. In the figure we have a beam with its loading(plus a force of 15kN), a pivot O and support at the rightmost point. I would say that in order to find the equivalent system, I...
45. ### Klystron beam current, drive frequency, LHC CW example

First of all I want to ask , do the LHC power klystrons work always in CW or are their frequency shifted to correct for timing of the bunches in the LHC tubes in case something isn't aligned or doesn't that ever happen? Also how do they drive the klystrons at LHC or other CW operation from an...
46. ### Statics Question -- Analyzing the forces on this supported beam

Can someone please tell me why I get two different result of the value of Cy (please see attached image for more detail)? Am I doing a mistake? If yes, what is my mistake?
47. ### Calculate the residual stress on a beam after bending

Hello everyone, I hope you can give me hand with what I will present. I have a beam with cross-section shown below. I considered a simple linear hardening model for predicting the stress and strain developed by bending the beam on the radius ##R_0## around the y-axis, where: The strain...
48. ### B Energy loss in the beam of LHC

Generally, one would expect the beam to lose its content (energy or particles) if it hits anything before its reaching its target. The whole idea of maintaining (conventional) vacuum using pumps or other means is to minimize that loss. But is it possible that there could be a beam loss purely...
49. ### I Commutation of Beam splitter operator with Displacement operator

I have a beam splitter operator (a†)b +(b†)a. Does it commute with exp(αâ†-α*â). Here a and â† are creation and lowering operator
50. ### Measuring the length of a moving Beam in two different directions

v_g+v_e=15/t_1 v_g-v_e=10/t_2 v_g=s/(t_1-t_2) But there are too many unknowns. What am I missing?