shear force

A force acting in a direction parallel to a surface or to a planar cross section of a body, as for example the pressure of air along the front of an airplane wing. Shear forces often result in shear strain. Resistance to such forces in a fluid is linked to its viscosity.
Also called shearing force

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More About Shear Force

What does shear force mean?

Shear force is a force acting in a direction that’s parallel to (over the top of) a surface or cross section of a body, like the pressure of air flow over an airplane wing.

The word shear in the term is a reference to the fact that such a force can cut, or shear, through the surface or object under strain. It is also sometimes called shearing force. It’s important not to confuse it with the general phrase sheer force, in which sheer is an adjective meaning complete or absolute.

You’re most likely to see the term shear force used in the context of architecture and construction. That’s because shear forces are an extremely important consideration in construction. If they haven’t been calculated correctly, the structure might be unstable.

Why is shear force important?

Shear force is one of the most common physical forces you’ll encounter in everyday life. Every time you cut or bend something, for example, you’re applying shear force.

Shear forces are unaligned but parallel forces acting on a surface or on an object. Being unaligned means that one force is going in one direction, and another force is going in the other direction. A very simple demonstration of this is if you take a piece of paper and pull it towards you with one hand while pulling it away with the other—the paper tears as a result of shear forces.

Shear forces are important to consider in building design and engineering. For example, calculating shear force helps to know how much weight a beam (like one that holds up a roof or floor) can take before it bends or breaks. While you’ll most often hear shear force used in the context of building and construction, it’s important to remember that many things are subject to shear forces, from airplane wings to the smallest bolts.

Did you know ... ?

Shear force isn’t quite the same thing as shear stress. Shear force is the force acting on something, but shear stress is the strain on the object or surface that’s caused by that force. It’s the difference between the weight pressing down on a beam (force) and how that weight impacts the beam (stress).

What are real-life examples of shear force?

Shear force is most commonly discussed in the context of construction and engineering, but it’s a common force that we experience all the time without thinking about it.

Should give spider silk a go – it's slowly biodegradable, non-immunogenic, and assembles into stable structures under shear force :)

— Jólakötturinn 🕸️🎄 (@BlackWidowJola) January 12, 2020

A and B have holes drilled into the flats, and a hollow cylinder C is inserted into the two holes, pinning the parts together so they're locked together. If a force is applied to only A or B, the shear force tries to cut C so they separate.

How do I calculate the failure point?

— Andrew Zonenberg (@azonenberg) January 9, 2020

What other words are related to shear force?

Quiz yourself!

Which of the following terms means the same thing as shear force?

A. sheer force
B. shearing force
C. shear stress
D. all of the above

Shearer Shearing

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