- Normal strain
As with
stress es, strains may also be classified as 'normal strain' and 'shear strain ' (i.e. acting perpendicular to or along the face of an element respectively). For anisotropic material that obeysHooke's law , anormal stress will cause a normal strain.Strains are relativedisplacements - they are the actual displacement divided by the length before the strain was applied.Rigid body motion s don't produce strains. Normal strains produce "dilations", however they merelystretch the body along the axis of application (negatingpoisson's ratio and the effects it causes). As such, a normal strain will cause the following effects:* Any line
parallel to the strain axis will increase by an amount proportional to its length and the amount of strain. (See below).
* Any lineperpendicular to the strain axis will have no length change (negatingPoisson's effect .)
* Any line not perpendicular nor parallel will have a length increase based uponvector algebra .
* Normal Strains will become Shear strains for a rotation of theframe of reference . SeeMohr's circle for strain.Normal strain, :
The 'stretch' of an element over its original element length is thus::
See also
*
Shear strain
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