# Can strain exist without deflection?

• wasif

#### wasif

Lets take an example of a person pushing a thick wall, of course no deflection in the line of action of force is seen but can strains be induced in it, like surface slips?

The definition of strain is dL/L. Stress less than some limit should cause no strain.

Lets take an example of a person pushing a thick wall, of course no deflection in the line of action of force is seen but can strains be induced in it, like surface slips?
What are surface slips?

Chet

The definition of strain is dL/L. Stress less than some limit should cause no strain.
This is not correct. Any stress will cause a strain. But, if the stress is very low, the strain might not be significant.

Chet

Dr.D and billy_joule
via wikiapedia: http://en.wikipedia.org/wiki/Deflection_(engineering), http://en.wikipedia.org/wiki/Deformation_(mechanics),

I believe you can have a displacement at the line of action even in a thick wall. Unless there is some sort of rigid constraint that prevents that.

deflection is the degree to which a structural element is displaced under a load. It may refer to an angle or a distance.

strain is a normalized measure of deformation representing the displacement between particles in the body relative to a reference length.

So, I think it depends on the constraints. Otherwise there will be a strain under any deflection, no matter how small. Check out my picture it may help.

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strain will be induced due to its own weight also.So,strain will always be present.

What are surface slips?

Chet

Hi chet, thanks for the reply

Surface slips by which i mean the deformation of the slip planes at the surface if the force is just enough.