What is Bending stress: Definition and 52 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. S

    Engineering Crane at 45-degree angle supports load -- Find principal boom stresses

    The book's answer key shows a normal stress P/A as a result of adding the 350LB force from the cable to the cos(45 degrees)(350LB). It shows both of these as compressive forces. I can see how the cos(45 degrees)(350LB) is compressive; the force of the 350LB load is bending the boom clockwise...
  2. D

    Lewis Bending Stress: Why Does Lewis Factor Depend on x?

    How come in the lewis bending equation for spur gear tooth does the lewis form factor depend on x? x being the vertical distance measured from the triangle that is formed from the base t and fillet a. I know that you can express the height h and width t in terms of x such that x= t^2/4h, but why?
  3. G

    Out-of-plane bending stress on an I-beam

    I know the out of plane bending stress equation for a curved I beam but I am trying to figure out where it came from. sigmaR = tFlange * sigmaNormal/(radius of curvature)
  4. T

    Bending Moment & Bending Stress

    Hello all I was wondering if anyone could figure out the what the equation below means, specifically the W term? The equation to calculate bending stress for a cross section that i have used and i know is correct is:- Bending Stress = Moment (M) * Distance From Neutral Axis (Z) / Second...
  5. T

    Calculating the bending stress of a simply supported beam

    Hello all I am trying to calculate the bending stress of a simply supported beam with a load of 12kn at the middle of a 6m span, member depth of 0.016m I have drawn both the bending moment and shear force diagram. I want to know the following:- 1) When calculating the bending stress would...
  6. dustball23

    Calculating bending stress on a pipe

    In both designs, a PVC pipe is being bent 90 degrees, fixed at each end. In both designs, the pipe is fixed at both ends. In both designs, the pipe is 1" (inner diameter) Schedule 40 PVC pipe, 450 PSI. Material code PVC 1120. NSF pw-G ASTM D1785 PPFA 02199101H6BX 0934. In design A, the length of...
  7. Joe591

    Help with a Bending Stress Calculation

    I've attached a photo of a "problem". How would you calculate the stress at the area in question? I seriously doubt that the bending stress would vary linearly throughout the whole meter of total length of the section. I would expect it to become zero long before it reaches the opposite...
  8. J

    What are other names for bending stress?

    Hello, I need to input the bending stress from a database I am not sure what name it is, would it be yield strength or tensile strength? thanks
  9. Jesse Niekamp

    Bending Stress on a Protective Cover

    Homework Statement A 30kg pallet falls from a height of 2m onto a protective cover. The cover has an area of 269m² and an overall thickness of 10.9mm. a. What is the force/pressure on the cover? b. What is the bending stress on the cover? Homework Equations F=ma bending stress =...
  10. K

    Parallel Axis Theorem / Bending Stress

    Homework Statement find bending stress in x and y dir Homework Equations I = bh^3/12 + ad^2 Stress = Mc/I The Attempt at a Solution I = bh^3/12 + ad^2 Stress = Mc/I see attached calculations My prof gave us a question where we have a motor (20" tall) sitting on a frame with a load of...
  11. D

    Applying Bending Stress to a Model of Ship Section

    Good Afternoon. My name is Dimas M. Rachman, i am an undergraduate student majoring in Ocean Engineering/Naval Architecture. I am currently working on my final project. I need to model the effect of bending stress "inside" a plate of ship's deck with Ansys Workbench. Here is a review about...
  12. S

    Tube Bending Stress: Hand Calcs vs FEA Analysis

    I have ran an FEA simulation on a lever to work out the stress on the part. I have now started doing some hand calculations to validate the software results and am struggling to get the values to match up. I am unsure whether my calculations are wrong, or whether the software is incorrect. The...
  13. F

    Moment applied causing bending stress in beam

    Homework Statement From the solution , it's clear that the top part of the beam undergo tension , while the lower part undergo compression . Homework EquationsThe Attempt at a Solution But , i don't understand why it is so . When the moment is applied in the horizontal axis , the structure...
  14. N

    Calculating Bending Stress for a Cantilever Beam

    Hi, I'm trying to calculate bending stress for a cylindrical beam. I'd like to have my result double checked because I got an answer that doesn't make sense to me. All of this is personal research, so I'm not very confident in my answer. It's a cantilever beam with a point mass of 347.4 oz. on...
  15. C

    Understanding the Difference Between Bending Stress and Normal Stress in Beams

    Homework Statement https://en.wikipedia.org/wiki/Bending [/B] form the link, we know that σ represent the bending stress, I'm wondering can I call the bending stress as normal stress act at the cross sectional area of beam?Homework EquationsThe Attempt at a Solution IMO, they are not the...
  16. S

    Determine the absolute maximum bending stress of the beam.

    Homework Statement If w = 74 kN/m , determine the absolute maximum bending stress in the beam in MPa. Homework Equations I'm not too sure how to go about my calculations. Please help! The Attempt at a Solution I = [(1/12)*(200*256^3)] - [(1/12)*(192*250^3)] = 29.62*10^6 F = 74*24*1000? [/B]
  17. A

    How can I get the force from the bending stress

    Hello all, I am a new member of PF.I have a basic question about the bending stress, I remember somewhere I saw this part, but can't find out it. Could you give me a answer? Given: 1, M-moment applied on the section. 2, I-Section modules 3. y-distance from shear center Solution F,how much is the...
  18. R

    Calculating bending stress for pipes

    I'm making a robotic structure using hydraulics and pipes, and I need to choose what size pipe and thickness I will be using. I've searched online to the best of my ability but all I got were equations for I-beams. I've taken statics in college so I know how to calculate all the loads in a...
  19. J

    Question about the location of max bending stress in a beam

    Hello guys, I have a simple question about the max bending stress in a beam. We know that in a cantilever beam, the biggest moment occurs at the wall. This is also the location of the max stress with equation stress= M*y/I , However, in a simple supported beam, we have This time, the max...
  20. G

    Can Bending Stress on Curved Beams Be Calculated Using a Simple Formula?

    I have a problem where I'm considering a curved member of circular cross section bent in the shape of a half circle and fixed at the base. A force is applied perpendicular to it (so in the picture, the dot is the force going 'into' the screen at the top view) and I'm trying to find the bending...
  21. DrVirz

    Where is the point of maximum compressive stress in bi-axial bending?

    Hi all, I've attempted this question however my solution seems too simple..? I have taken the point 'A' (bottom right corner of beam) as the point with max compressive stress, I am not sure if this is correct. I have just assumed this by observation.
  22. T

    Explaining Bending Stress in Cantilever Beams

    Hey everyone, I was just wondering if someone could explain to me what Bending stress is? Supposed you have a cantilever beam with a point load at the free end, I know that the bending stress will decrease as you move away from the fixed end? but why? and how can you back that up? Also, as...
  23. spikeybrummy

    Convert solid shaft to hollow shaft

    I have a "bending stress" question, which is causing me "actual stress"... I have a solid 30m Aluminium shaft, which I need to replace with an equivalent hollow shaft, but I am having difficulty in calculating the internal and external diameters. The solid shaft diameter is 0.118m, and all I...
  24. T

    Tensile Strength & Bending Stress of Metal Sheet

    Dear Friends, Merry Christmas to All. I am pleased to join this forum of Physics Experts. Please advise what is difference between tensile Strength and Bending Stress of Metal Sheets (Generally below 3.00mm and lighter). I very often encounter with cracking of steel sheets while bending in...
  25. 1350-F

    Brittle Materials: Bending Yield Strength

    It seems to me that the ultimate strength of a brittle material can be easily determined by a bending test, but what about the yield? In the brittle regime, I can see how you couldn't, since the sample would fail before it would flow significantly. However, brittle materials can be made to flow...
  26. T

    Bending Stress in Top of T-Beam

    Homework Statement T-Beam is Steel with E=200GPa Find Max bending stress MC/I (right side where no glue)[/B] 80KG Load at Point "A" shown on the Top view Blue stuff is glue, the right side has no Glue, so its just empty space 2. The attempt at a solution I = BH^3/12 , where B = 0.04m H =...
  27. G

    Calculating strength of steel square tubing

    Hello, I'm enrolled in College in the civil engineering program and am looking for guidance with calculating strength of steel square tubing. We are making a project that has parameters. 1- Must be made of steel 2- 4"x6"x36" is maximum OD of section. 3- 14 lbs is maximum weight 4- the load...
  28. K

    Question related to Bending Stress and Shear Stress of a I shape beam

    1. Homework Statement The beam ABCD with the cross section has pin connections at B and C and is subjected to a uniformly distributed load w. If the allowable bending stress is 150MPa and the allowable shear stress is 80 Mpa. ( Hint : the horizontal reaction forces at A and D are both zero)...
  29. R

    Beam problem finding max bending stress

    Alright so I drew it out like did the reactions and everything then I realized I need to include the diameter of the beam. How do I find the max bending stress while using the diameter of the beam? All I need to know is what exactly I do differently compared to drawing the bending moment...
  30. J

    Structural Mechanics. bending moment and bending stress

    [b]1. Homework Statement [b/] A timber beam, with rectangular cross section (h × b) is reinforced with additional full width (b) steel plates. There is a plate of thickness t securely connected on the bottom and a plate of thickness 2t on the top of the timber to ensure composite action in...
  31. A

    Analysis of scoop stretcher - deflection and bending stress help

    Analysis of scoop stretcher -- deflection and bending stress help I wanted to do a theoritical force analysis on the scooping part of scoop stretcher (a tapered rectangular plate). Can anyone suggest how to determine its deflection and bending stress ?
  32. J

    Calculating maximum bending stress in an I beam?

    Hello all, I am confused on how to calculate the maximum bending stress in an I-beam. I found the maximum deflection in each beam where the load is placed at the center of the span. I also know all the cross-sectional dimensions of the I-beam. Is it now possible to calculate it? Thanks
  33. J

    Bending stress due to 2 bending moments in different planes

    1. The scenario is the same as this (with a circular cross section): http://upload.wikimedia.org/wikipedia/commons/c/cf/Poutre_flexion_deviee.svg 2. Do I simply calculate the stresses from each bending moment and add them together? Or take the resultant vector and calculate...
  34. M

    Calculating Maximum Bending Stress of a Beam

    A uniform simply supported beam, 5 m long and having a cross-section as shown, is to support a load which varies linearly from zero at the left hand support to a magnitude of 20 kN/m at the right hand support. Determine the position and magnitude of the maximum bending stress. ANS : 140 MPa...
  35. S

    Length & Bending Stress: How Does Beam Length Impact Stresses?

    if you have a beam or something, anchored at one end and apply a moment at the other end, then the bending stress is given by M*y / I, where I is the moment of inertia of the beam. what affect does the length of the beam (i.e. the distance between the anchor and the end of the beam, where the...
  36. C

    Determine bending moment and bending stress

    Homework Statement A timber beam, with rectangular cross section (h × b) is reinforced with additional full width (b) steel plates. There is a plate of thickness t securely connected on the top and a plate of thickness 2t on the bottom of the timber to ensure composite action in bending. The...
  37. F

    Understanding Moment of Inertia and Bending Stress in Physics Forums

    hi all , I am a new member in physics forums and I hope I can help and get benefit from this forums . I would ask anyone knows about the moment of inertia cos i have not study it before and I have to know it to solve a bending stress problem .. when I used the moment of inertia for...
  38. M

    Maximum bending stress in wooden beam

    Homework Statement A timber beam will be used to support part of the ceiling of a house. It is going to be attached to the walls as a simply supported beam, Figure 6. If three forces are applied to it and considering the weight of the beam as a uniformly distributed load of...
  39. K

    Bending Stress Help: Find Resources Here

    Hello guys. I need help to understand the calulation of bending stress. This topic is discussed in our lecture, and the prof shows us an animation for it. However, this topic is not on the textbook and the prof refuse to give us the link for the animation. I am wondering, do any of you know...
  40. G

    Help me calculate a calculated bending stress (psi) in cantilever beam?

    Homework Statement I am using a Vishay strain indicator with it hooked up to a strain gage hooked up 1" away from the wall on the solid beam. The beam is .5" by .5", and it is solid. The beam is 16" long and I am putting weights at the end of the beam. The weights are 1, 2, 5, 10, 15, and 20...
  41. G

    Bending stress in gear/bearing puller

    Homework Statement I have a project where I have to determine the bending stress on a gear/bearing puller. It looks like this: http://www.posilock.com/PDFs/106.pdf . The free body diagram I'm pretty sure would look something like this: http://img20.imageshack.us/img20/1918/fbdi.jpg...
  42. G

    Local bending stress calculation in long beams

    Hi everyone, Recently I faced a problem in calculating bending stress in a long UPN profile "flange" due to concentrated force. It seems that the regular/familiar formula for bending stress in a finite/short element does not applicable in local bending of long/infinite beam. See sketch...
  43. P

    How can I estimate the bending stress for a hollow tube under uniform load?

    Dear All, Please see the picture. I need to find the bending stress for that profile. Its hollow tube dia= 38 mm, 4 mm thick. its is acted with udl of 500 N/m2 on its outer surface. How can I estimate the bending stress, deformation. Assume it as mild steel with E = 200 Gpa, poission...
  44. E

    Is max bending stress the same as the yeild strength

    i don't know whether to use the yeild srength or allowable stress to determine section sizes of a beam please help me :) thank you.
  45. O

    What is the formula for bending stress of a plate with a central point load

    I have a steel deck (a) 2000mm x (b) 4200mm overall comprising 12.5mm durbar plate (grade S275) welded to RSA ribs at 400mm spacings, the plate is unsupported in the other plane (4200mm span) with the exception of end plates. I wish to drive a forklift truck over the plate with a wheel load of...
  46. S

    Calculating Maximum Bending Stress for a Beam - I'm Doing it Wrong!

    bending stress in beam, help me ! Homework Statement Homework Equations singularity function bending stress (max) = { (M max)/I } * ( a/2) The Attempt at a Solution after writing the singularity function, and compute reactions force I found that the maximum bending moment should be 12.04...
  47. A

    Bending stress + bending moment

    Homework Statement A steel strip of breadth 50 mm and depth 3 mm needs to be bent around a drum of diameter 4 m. What bending moment is required and what will be the maximum stress produced? The modulus of elasticity of the steel is 210 GPa Homework Equations \frac{M}{I}...
  48. J

    Maximum Bending Stress in Beam

    Homework Statement Note the attachment. I scanned it out of my book and I drew a FBD on it. Homework Equations The Attempt at a Solution Ok so i haven't gotten very far at all with this one because it just doesn't seem to have enough information. So first I summed the forces...
  49. 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...
  50. C

    Bending stress of beam on flat surface ?

    I am designing a spinal disc with 2 metal endplates. These endplates are rectangular in shape and are fixed to form a flat contact surface with the vertebrae bone surface. My question is based on the bending stress of these metal endplates. I need to work out the possible thickness of these...