Shear Stress: Examining the Discrepancy

In summary, the author states that the shear stress is constant over the bottom face of the segment in figure 7-4, but the figure shows varying bending stresses. Both the profile view and 3D view show the constant longitudinal shear stress at the bottom of the plane. The bending stress is shown to vary from maximum compression to zero at the top, and then to maximum tension at the bottom in figure 7-4b, while figure 7-4c shows the constant shear stress at the bottom across the thickness of the beam.
  • #1
fonseh
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Homework Statement


In the notes, the author stated that the shear stress is constant over the bottom face of the segment ... why in figure 7-4 , we can see that the shear stress varies ?

Homework Equations

The Attempt at a Solution


Which is correct ? The red circled part or the figure ? [/B]
 

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  • #2
fonseh said:

Homework Statement


In the notes, the author stated that the shear stress is constant over the bottom face of the segment ... why in figure 7-4 , we can see that the shear stress varies ?

Homework Equations

The Attempt at a Solution


Which is correct ? The red circled part or the figure ? [/B]
They are both correct, the Profile view shows the shear stress at the bottom, constant across the width t, the other views show the varying bending stresses , not shear stresses, but if you look carefully in the 3D view you will find the constant longitudinal shear stress at the bottom of the plane ( [itex]\tau[/itex])
 
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  • #3
PhanthomJay said:
the other views show the varying bending stresses , not shear stresses,
what do you mean by the other view here ? the figure 7-4 (b) in the first photo ?
 
  • #4
PhanthomJay said:
They are both correct, the Profile view shows the shear stress at the bottom, constant across the width t, the other views show the varying bending stresses , not shear stresses, but if you look carefully in the 3D view you will find the constant longitudinal shear stress at the bottom of the plane ( [itex]\tau[/itex])
shear stress at the bottom plane ?
In the profile view , we could see that the stress ( i am not sure bending stress or shear stress) varies linearly ... But , you said it's constant across the width ? I'm confused
 
  • #5
You should have long learned about bending stresses before tackling distributed shear stress. Figure 7.4b shoes the bending stress varying from max compression to 0 from top to NA, then up to max tension at bottom. Shear stress is shown in fig 7,4c as constant at the bottom across the thickness, t.
 
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  • #6
PhanthomJay said:
You should have long learned about bending stresses before tackling distributed shear stress. Figure 7.4b shoes the bending stress varying from max compression to 0 from top to NA, then up to max tension at bottom. Shear stress is shown in fig 7,4c as constant at the bottom across the thickness, t.
so , in figure 7.4 b , the figure shown is the bending stress across the vertical length of beam ?
 
  • #7
fonseh said:
so , in figure 7.4 b , the figure shown is the bending stress across the vertical length of beam ?
Yes, My/I bending stresses.
 

1. What is shear stress?

Shear stress is a type of mechanical stress that occurs when two surfaces slide against each other in opposite directions. It is caused by forces applied parallel to the surface, rather than perpendicular to it.

2. How is shear stress measured?

Shear stress is typically measured in units of force per unit area, such as pounds per square inch (psi) or newtons per square meter (N/m2). It can also be measured using specialized equipment, such as a shear stress sensor or a rheometer.

3. What causes shear stress?

Shear stress is caused by external forces acting on a material, such as friction or tension. It can also be caused by the internal forces of a material, such as when a solid material is deformed or when a fluid is flowing over a surface.

4. What are the effects of shear stress?

Shear stress can have a variety of effects on different materials. In some cases, it can cause materials to deform, break, or fail. In other cases, it can be beneficial, such as in the manufacturing of certain products or in the mechanics of fluid flow.

5. How is shear stress related to shear rate?

Shear stress and shear rate are closely related, as shear rate is a measure of the velocity at which shear stress is applied. In general, as the shear rate increases, so does the shear stress. However, the relationship between shear stress and shear rate can vary depending on the type of material and the conditions under which it is being tested.

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