What is Bending: Definition and 665 Discussions

In applied mechanics, bending (also known as flexure) characterizes the behavior of a slender structural element subjected to an external load applied perpendicularly to a longitudinal axis of the element.
The structural element is assumed to be such that at least one of its dimensions is a small fraction, typically 1/10 or less, of the other two. When the length is considerably longer than the width and the thickness, the element is called a beam. For example, a closet rod sagging under the weight of clothes on clothes hangers is an example of a beam experiencing bending. On the other hand, a shell is a structure of any geometric form where the length and the width are of the same order of magnitude but the thickness of the structure (known as the 'wall') is considerably smaller. A large diameter, but thin-walled, short tube supported at its ends and loaded laterally is an example of a shell experiencing bending.
In the absence of a qualifier, the term bending is ambiguous because bending can occur locally in all objects. Therefore, to make the usage of the term more precise, engineers refer to a specific object such as; the bending of rods, the bending of beams, the bending of plates, the bending of shells and so on.

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  1. T

    Bending Moment Maximum Force

    Hi For a project I am doing i need to know the maximum load an "I" Beam made out of balsa wood can take. Looking through the internet I found the "Euler Buckling Formula" F = \frac{E I pi^2}{l^2} When I use this formula I get a load which is too big, and I think this mght not be the...
  2. D

    How Do You Plot a Bending Moment Diagram for a Propped Cantilever Beam?

    Homework Statement A steel (Young's modulus = 210x109N/mm2) propped cantilever beam (Figure 1) supports a uniformly distributed load (UDL) of 20kN/m. The beam cross section is a 150mm x 75mm x 8mm rectangular hollow section (RHS), i.e. 150mm deep, 75mm wide and has an 8mm wall thickness. The...
  3. B

    Sheet Metal Bending Question

    I need a piece of .125" steel sheet metal to be 21" wide after a 1" lip is bent to 90 degrees on one side. How wide does the initial piece of steel need to be before bending in order to achieve this? I know it will be more than 22", but how much more? If I recall its fairly simple to figure...
  4. R

    Deriving Bending of Light from Maxwell's Equations

    Can the bending of light because of gravity be derived from the Maxwell equations written in curved space time, i.e., \frac{1}{\sqrt{-g}}\partial_\mu(\sqrt{-g}F^{\mu\nu}})=0 In all the examples the bending of light is treated as a massless particle traveling on a light-like geodesic (if I...
  5. W

    Calculating bolt size required to prevent beam bending

    The attachment shows a side section of a water tank.(lined with Marine Ply) The section will be bolted to a fixed bottom section with 4 bolts. I'm trying to determine the size and strength of bolts required to do this. My attempt at starting this problem is shown in the attachment...
  6. W

    Help calulating bolt strength to prevent beam bending

    Homework Statement The attachment shows a side section of a water tank.(lined with Marine Ply) The section will be bolted to a fixed bottom section with 4 bolts. I'm trying to determine the size and strength of bolts required to do this. Homework Equations Hydrostatic force? UDL...
  7. N

    Circular flange bending stress problem

    Homework Statement Hi guys I've got a problem on hand which has haunted me for sometime and I thought it might be a good idea to post it here to ask for your opinions. As you can see in the picture, I've got a circular flange. What I am intending to do is to simply find out the...
  8. S

    Simply supported beams bending moment

    I don't know how to do the following question, The beam shown is under the action of a uniformily distributed load w of 2 kN/m between the supports and a point load of 2 kN at the end point. Determine the bending moment in kNm at point A situated 3 m to the right of the left support. Round off...
  9. T

    Bending Moment Diagram for Trapezoidal Distributed Load: Homework Help

    Homework Statement I have a problem which involves me drawing the bending moment diagram for a trapezoidal distributed load. I understand the bending moment diagrams for a uniform distribution, and partially for a triangular distribution, however i am struggling to link the two for a...
  10. S

    What is the required load to bend a steel plate in a radius of 508mm?

    Hi... I am doing a project to calculate the load required to bend a plate.. Here are the details.. There is steel plate of 2000mm width and 25mm thcikness placed over 02 support steel rollers of diameter 180mm. Another steel roller of same diameter press from the top of the plate at the...
  11. P

    Shear Force Due to Bending HW question

    Homework Statement My prof gave us this take home quiz to complete to prepare for our actual quiz. We are studying Shear force due to bending of beams (2nd year mech eng). In this question he told us that the shear force (V) can be applied at any of the points and that we would need to find the...
  12. B

    Compensating Robot Arm Deflection for End Weight

    Hi guys, I'm doing a robotics project that requires me to compensate for the bending of the arm due to an end weight. I can calculate the deflection at the end of the arm for a given weight e.g. End link horizontal (90 degrees), end weight = 1000g, deflection = 10mm From this i can calculate...
  13. F

    Band bending in a thin film semiconductor

    Hello! There're very thin (4-15 nm) semiconductor films (passive film) formed on stainless steel by electrochemical method. In a electrochemical cell, I applied potential on stainless steel electrode to adjust Fermi level of the semiconductor passive film. I think that band bending take place...
  14. A

    How to solve for bending moment?

    Hello, I'm a newbie here, please help me to solve for the bending moment of my design airplane. I want to know if my wing spar is strong enough to support the weight of my design which is 490 lb. I want also to know if what is the breaking point of the wing spar. Please see the attached picture...
  15. H

    Shear forces and bending moments on a box barge, formulas

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  16. L

    Bending a Candle Flame - What Causes It?

    I'm not sure if this goes here, but there isn't a "General Science" section. Today I got a glass of really cold water, and noticed a candle on the table. I felt like collecting some carbon on the bottom and held the glass over the flame. The flame bent away from the bottom of the glass...
  17. T

    Beam Bending of a Non-Straight Beam

    Hi all, I am designing a gear lever for a small race car, and am looking to validate my FEA of the lever through the use of hand calculations. The beam is not straight, and i have never tackled a problem like this before. I am using Roarks Formulas for Stresses and Strains, however am...
  18. S

    Bolt dimensions In plate bending

    Hey I have this plate, and as you can see it has 4 bolt connections and no other. When applying the load bending will occur in the plate. I am interested in making the diameter of bolt as small as possible. My problem is though that I only can see the shear forces in the plate. How can I...
  19. xunxine

    Can You Bend Optical Fibres Too Much?

    Although optical fibres do not break easily, is it possible to bend the optical fibre too much that light that travels within the optical fibre will strike the wall at less than the critical angle and thus escape from the fibre through the wall? Pls enlighten me. Thanks! (I came across this...
  20. T

    Why is the bending of waves related to wavelength?

    Why is the "bending" of waves related to wavelength? Hi! As stated in the title, my question concerns the "bending" of waves. (I'm quite sure that "bending" is not the proper term, so if you know the correct one, please tell me.) Let's say that we investigate waves in a ripple tank. We create...
  21. T

    Singularity Functions for Beam Bending

    There is a beam of width 10cm, and vertical reaction loads on each end (x1 = 0cm, x2 = 10cm). Starting from the left end of the beam, we have a vertical distributed load of 2,000 N/m spanning from 0cm to 5cm. Finally, we have a 1,000 N point load located 7.5cm from the left end of the beam...
  22. D

    Bending of members made of several materials

    when given a non homogeneous cross section, i know that i can find the bending(normal ) stresses by transforming the cross section into a homogeneous one by multiplying the area of one of the materials be 'n', where n=E1/E2, then i solve normally, finding the centroid of the new cross...
  23. D

    Max load bending on steel tube.

    I'm trying to calculate the max load of a rack made of 3X3X1/4 steel tube. It is 8ft long and 4ft wide. I just want to calculate the max load (distributed load) in bending cross the 8ft and also in compression for the legs. i can't find the right formulas. can anyone help? so far i what i...
  24. T

    Bending of light and the travel distance

    a question has been puzzling me for a while is : "is the distance traveled by a beam of light from point A to Point B in a flat space-time differs from the distance traveled by the same beam of light from the same point A and The Same point B but in a curved space-time ?" In other words ...
  25. D

    Understanding Stress Distribution in Beams: Plotting Sigma(M) as a Function of Y

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  26. D

    How Does Material Heterogeneity Affect Beam Stress Analysis?

    for the folowing beam made up of a top half where E=210Gpa and a bottom part where E=70Gpa a=0.2m t=0.024m, b=0.04m i am asked a few different things a)to find the shear forces and bending moment arrays in the beam b)plot the normal stress as a function of the moment, how do...
  27. D

    Find Ratio of d/b for Minimum Stress in Beams & Bending

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  28. D

    Loading reaction with shear and bending moment diagrams

    a motor vehicle has a wheel base of 3m. four posta ramp with two wheels each side. ramps front wheels have 6kn and rear 8kn. determine the reaction of the supports on the beam? vehicle is raised 2.25 m vertically this is done in 45 seconds calculate power of electric motor required use...
  29. E

    Max Bending Moment of Rigidly Clamped Beam

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  30. S

    Applying a Bending Moment to a Plate with Forces

    I'm using FEA to simulate an in plane bending moment on a plate. The moment is 200Nm, and the plate is 80mm tall. Do I simulate the forces on the edge in situation (a) or situation (b)? It's a seemingly simple question, but people have put doubt in my head, I hoped a fresh mind might...
  31. J

    Shear Force and Bending Moment Diagram

    Homework Statement I have to find the Shear Force and Bending Moment diagrams for this problem. The lengths in the picture are 1.2m each and the peak force is 4kN/m and I calculated the support reactions to be: Ay=4,8kN (up) Ma= 5.76kN.m (anticlockwise) Homework Equations These are what I'm...
  32. T

    Solving Beam Bending Problem: 600N Load, 3.5mm Radius, 193GPa Young's Mod

    Homework Statement Hi there all, I am designing a pedal box for a vehicle, and its adjustment is does by removing some pit-pins and sliding the pedal box along a rail and reinserting the pins. I need to calculate the stresses in the pin given a 600N total load applied by the feet of the...
  33. M

    Beam Bending, beyond the basics, a little

    Ok, I am fairly comfortable with beam bending equations for simple rectangles. However, I am totally confused on how to approach other cross sections... like a channel can someone help? Or point me to a good online instructional resource? I have googled all I can think of... -Mark
  34. W

    3x3 or 4x4 square tubing bending strength

    I need to erect a hoist beam with a 10' span using square tubing. Which is stronger, 3"x3" 1/4" wall or 4"x4" x 3/16"? Also, how much weight could I lift at the center?
  35. M

    Stress due to bending of fillet weld joint

    Evening everyone, i have been referring to Shigleys "Mechanical engineering design" (pages 349 to 351) regarding a welded joint I am looking at. wanted to compare my manual calcs to sum FEA. My joint is a circular shaft which is fillet welded to a base plate. A load is applied to the end...
  36. S

    Shear force and bending moment diagrams

    Hi. The question is: Draw the shear force and bending moment diagrams for the simply supported beam shown below. State the values of the greatest shear force and bending moment, and the bending moment at D. The diagram is attached as is my attempt at the answer. I hvae not stated the values of...
  37. C

    The math involved in bending a rod

    I have a door lever which has a 90 deg. bend. I need to calculate the length that this lever would have to be if it were in the form of a straight rod, prior to being bent. I know I have all the input data, I'm just not sure how to express this algebraically. For example, I know that the...
  38. M

    Which workpiece has a greater spring back effec on bending?

    which workpiece has a greater spring back effec on bending? http://img94.imageshack.us/img94/6549/springback.jpg Should be A or B? How do i figure it out? by using spring estimation equation? thank you
  39. S

    How Much Bending Moment Can a Plyweb Beam With Timber Flanges Carry?

    Calculate the maximum B.M the symmetrical section can carry Plyweb with timber flanges (50x100 c.s.a) The maximum stress = 1.0N/mm^2 The structure is essentially an I beam with dimensions as follows. The central beam has a width of 25 and height of 500. The four flanges which...
  40. H

    Tensile Test vs. Bending Test Stresses

    This is more of a theoretical question. Not sure if this should be under this section or Mechanical Engineering. Homework Statement For 1018 steel, I tested the UTS to be about 83 ksi for a dogbone specimen with a circular cross-section. However, when I determined the Ultimate Bending...
  41. J

    Cantilever beam bending moment and shear force

    Homework Statement im trying to write a program for a class but first i need the formulas for the bending moment and shear force. i have the displacement and angle of the cantilever beam under a point load: Y = -[(WX^2)/(6EI)][3a – x] for 0<x<a Y = -[(Wa^2)/(6EI)][3x – a] for a<x<L...
  42. T

    How can Castigliano's Method be used to solve for deflections in a cranked beam?

    Hello all I have a beam bending problem I need some help on. I need to calcuate the deflections at the load (and in the plane of the load) for a simply supported beam with equal point loads overhanging the supports. However my beam is cranked as shown in the attached diagram of the problem...
  43. R

    Calculating Bending Moment & Force of Table with 8 Tonne Mass

    Hi , I need to find out the forces and bending moments on, put simply a table. 4 stands are welded to a flat plate to resemble a table. An 8 tonne mass is placed on the table, which is distributed equally on the 4 corner stands. The stands are 2m high and the flat top is 2m by 0.4m. Each...
  44. marcus

    Back to the real world re Lorentz bending

    As far as I know there is no firm prediction of any Lorentz bending derived from mainstream Loop. The authorities on what Loop says or doesn't say are Ashtekar, Rovelli, and Freidel. These are the people that organizers of any major world conference on gravity and related science would normally...
  45. S

    Find the maximum bending moment

    The bending moment, M, at position x meters from the end of a simply supported beam of length l meters carrying a uniformly distributed load of wkN m^-1 is given by: M = w/2 l (l-x) - w/2 (l-x)^2 Show, using the above expression, that the maximum bending moment occurs at the...
  46. T

    Creating Coils from Copper Rod: Bending Process

    I'm working on a project, and I need to make coils out of 5/8" diameter copper rod, ideally with center line radii ranging from 3 - 10 cm, and with turn heights of 5 cm. Most metal shops near me don't have the capacity to do this, because there rolling machines are based off of cold bending...
  47. M

    Is Section Modulus the same as a cross sections bending strength modulus ?

    Is "Section Modulus" the same as a cross sections "bending strength modulus"? Good afternoon everyone, I am following an ECE directive that sets out the requirements for the properties of a "Rear underun protection device" for the rear of a lorry. It states that the underun bar must...
  48. J

    How do I calculate the bending energy for a cross-linked beam network?

    Hello, I'm working on a project involving a cross-linked network of beam-like objects. We take these networks and apply extensional and shear strains to it, then apply an energy minimization procedure to find the optimal positions for all the cross-links in the new state. Therefore I have to...
  49. S

    Power to rotate shaft in bending

    How do you calculate amount of power needed to slowly rotate shaft under bending moment? This is not related to transmittal of torque. Given: shaft size span between support bearings bending moment value rpm Assume: slow rotation (ignore centrifugal forces caused by deflection)
  50. S

    Questions on Bending Stresses (which area will have 0 stress)

    http://en.wikipedia.org/wiki/Bending Please have a look on the right most picture in "Stress in large bending deformation". The Stress distribution shows that the bending center is not locate at the middle of the cross-section. (which also happen at connection caculation) However, base on...
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