What is Shear: Definition and 621 Discussions

Shear stress, often denoted by τ (Greek: tau), is the component of stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross section. Normal stress, on the other hand, arises from the force vector component perpendicular to the material cross section on which it acts.

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1. Engineering Shear stress problem: What decides the sign of Tau_V?

Im so confused on these solutions here for the shear stresses. Why is Tau_V sometimes negative and sometimes positive? Can someone please explain this and maybe illustrate? Here for example. Heres the solution for problem b): Here Tau_V (talking about F_xQ/(Ir) ) is negative, so how im...
2. A Lame parameter mu = shear modulus derivation (rogue factor of 2)

Hello, I am trying and failing to derive that the shear modulus ##G## is equal to the Lame parameter ##\mu##. I start with the linear, symmetric, isotropic stress-strain formula: $$\sigma = \lambda \mathrm{tr}(\epsilon) \mathrm{I} + 2\mu \epsilon$$ I then substitute a simple (symmetric) shear...
3. Engineering Analyzing Shear & Bending on Idealized Cross Section

As you can see from the picture, the cross section to analyze is idealized and the boom areas resulting from this are given. For POINT A) all I did was: for determining the shear forces, integrating the shear flows over the sides to compute the vertical and horizontal contribution of each side...
4. Engineering Calculating the safe load of a glued structure with given shear stress

I have tried to calculate the safe load with the equation of maximum shear stress, A = 4*6*10^-4, and the given shear stress 5MPa, but I couldn't seem to get the right answer which is 18kN.
5. 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...
6. Tensile and shear capacity of metals

Steel and other metals data sheets and mill specs most commonly quote some tensile strength metric, like Proof, Yield or Ultimate Tensile Stress. Less common is the value for shear strength. Often as rule of thumb the allowable shear stress is taken as half the allowable tensile stress but, when...
7. How is the slope of the shear force equal to the negative of the load?

At any point between A and C the point load is negative (downwards), in the shear force diagram: positive is upwards, so this slope is negative. The equation says the slope should be positive. Is this something to do with shear force sign convention?
8. I Derivation of Voigt's Shear Modulus

How did Voigt derive the average shear modulus of an anisotropic material, G=1/5 (A-B+3C), where 3A=c11+c22+c33, 3B=c12+c13+c23, 3C=c44+c55+c66? The original text is published in German about 100 years ago. I looked for other papers explaining this, but none has explained the derivation. They...
9. Understanding horizontal shear in beam with vertical load

In an I-beam, the shear flow is usually shown drawn as on the left, not as drawn on the right. I do not understand why. I do understand: The total horizontal shear force must be zero, consistent with statics.This is satisfied in both images. The vertical direction matches the direction of the...
10. I Water has no shear force but it can be sheared?

Is it true that water has no shearing force but it can be sheared? If so, would the sides of a glass holding water shear the water?
11. Shear lines from a FBD with distributed forces

, this is the FBD in question
12. Engineering Transverse shear stress calculation in non-slender built up members

Hi guys, this is an exercise I have been tasked to solve for an assignment. First of explaining you what I have done to solve it using the shear equation, in order to find the maximum shear stress and the shear flow in the juncture, one big question: how is it legal to utilize the shear formula...
13. Mechanics of materials - shear flow in built up members

Hello! I am new to mechanics of materials and I am very confused about the problem below. So the shear formula is: tau = VQ/It From the book (Hibbeler) I understand that Q is "y'A', where A' is the cross-sectional area of the segment that is connected to the beam at the juncture where the...
14. Hertzian contact pressure & shear stress

Hello, I am trying to get some intuition about the direction of the shear stress caused by the Hertz contact pressure. Once I exert some pressure downwards on a spherical object the direction of the Hertz pressure will be upwards. However, this case some shear stress to exist, but I can't see...
15. Engineering Statics project involving shear & moment diagram of a control arm

Part of a project I am working on (part #3…see description below) is asking us to find the internal loads (shear and moment) and draw the corresponding shear/moment diagrams of the control arm shown below. It’s a little tricky to me, because all of the members associated with these type of...
16. Engineering Maximum normal stress and shear stress

First, I am trying to find the external reactions in A and B, but I have only one equation relating ##V_A## and ##V_B##, what other relation could I use ? Once I find the reactions, I can find the external moment as well. Then, I may draw the diagram of moments in each cross section and then...
17. Shear stress damage due to thermal gradient

I'm trying to use my rudimentary understanding of material physics to understand a simple problem, and am getting stuck - I hope you can help! My idealized case involves a sheet of infinite extent in length and width direction, to which a linear thermal gradient in the depth dimension is...
18. The true definition of Poynting effect for simple shear

Consider a simple shear x=kY, y=Y, z=Z. How is Poynting effect defined? If the normal stress along y is 0 but that along x isn't 0, is that also a sort of Poynting effect?
19. Calculating Shear Stress from Shear Flow for Scientists

how to calculate shear stress using shear flow

A rectangle (plane strain/stress) is sheared on 3 edges (bottom fixed) so that it becomes a parallelogram. In theory this is pure shear and should undergo uniform deformation throughout the domain. The FEA result for this pure shear loading still shows stress/strain concentration on the bottom...
21. Election of cut placement for Shear flow -- Hibbeler's example

Hello. I am reading Hibbeler's Mechanics of Materials (ninth edition). Example 7.5 computes shear flow at a segment where there are nails attached to different boards. He chooses a cut like the one shown here: And gets (by symmetry between C and C') the shear flow q computing the first moment...
22. Shear flow in thin-walled members -- Hibbeler confusion

Hello: I was reading about thin-walled members under shear force, specifically example 7-7 of Hibbeler's Engineering Mechanics, Mechanics of Materials. First, the fourth Edition: As you can see above. He starts by computing the moment of inertia on the first equation by subtracting a rectangle...

39. Shear stress, Direct stress and factor of safety -- help please

hello, I'm new to this forum and I'm looking for some much needed help/guidance as i have absolutely no idea on how to workout my assignment! any help would be much appreciated
40. Shear and Tensile Strength of Bones

Hello there, I'm currently studying shear and compression. I am wondering, in my textbook, it says that most bone fractures are not caused by compression but by twisting or bending?? I mean bone's shear modulus is as great as that of a steel's, but its young modulus is far smaller than its...
41. Engineering Calculating Shear and Tensile force in a rivet at an angle

Hi all! I have used this forum a few times and it has been very helpful, however now I am stuck. I have completed the question above however I have conflicting information regarding the Tensile and Shear force being applied to the rivet. I use the following calculation for this: Shear Force...
42. Understanding Shear Force: How to Calculate and Interpret Shear Force Diagrams

Hello all I was hoping some could shed some light on the idea of shear force on members. I have the following simply supported beam:- Considering only the left of the beam to just to the right of F1; my gut instinct would be to say that the shear force or failure is greatest at the...
43. Shear Stress Distribution Along a Beam

I know that shear stress in horizontal beams has a parabolic distribution, so that the max shear stress occurs at the neutral axis. I also understand that for a beam subject to a distributed load with supports at its ends, the magnitude of the shear force is highest at the left and right ends of...
44. Shear strength of a cut I-beam

Hello, I'm in the process of building a 2 story townhome project and had a question on a beam. The structural engineer is calling for a cut I-beam on top foundation which spans over the garage (10') and the load will be placed on just the top flange (see attached). The structure will cantilever...
45. The normal and shear stresses

Hi! i have this exercise and solution : Exercise: steel plate given in figure (a) is joined by an inclined butt weld ,the plate is subjected to tensile stresses in both x and y directions, σ(x)=54 N/mm^2 and σ(y)=38 N/mm^2 , 1) Determine the normal and shear stresses of the butt weld...
46. Calculating Shear Force between a Moving Film and a Cylinder

If I have a catheter covered in a thin sheathe (think a cylinder, covered by a thin plastic film), how should I go about calculating the shear force it takes to unsheathe the catheter from the sheath (no torque here, just the catheter moving in and out)? I've thought about strain gauges (but...
47. Shearing / Cutting Force - Rubber bale

I have been assigned by my tutor to design a hydraulic guillotine (rubber bale cutter). After designing its features of the hydraulic, cutting blade etc. I tried to calculate the force needed of cutting a piece of Rubber bale (Natural as reference) having an ultimate tensile strength of 30 MPa...
48. How can I calculate the bending moment of a pin in double shear?

I have attached an Excel-worksheet in which the problem should be clearified. The problem concerns the calculation of the bending moment acting in a pin in double shear, experiencing a certain load from a hydraulic cylinder. The plate thicknesses should be taken into account. Specifications and...
49. I Find Frequency of Block Oscillation Due to Shear Force

Hi. I'm trying to determine the frequency of an block (roughly a rectangular prism) when the oscillation is due to a shear restoring force. Here is a diagram: In the derivation, ##\rho## is the density of the block,##G## is the shear modulus of the block, ##y## is the elevation of the element...
50. Find an expression for the shear stress of this figure

Summary: I have trouble to define the y distance in my coordinatesystem I need to find an expression for the shear stress on the I figure, where the green parabola illustrates the function. I made a cut, where I defined the length from the start of figure I to the cut as z1. The formula for...