- Shear strain
Shear strain is a strain that acts parallel to the face of a material that it is acting on.
Normal strainacts perpendicular to the face of that it is acting on. There are two ways to interpret shear strain: the average shear strain and the engineering shear strain. The variable used to denote average shear strain is while denotes engineering shear strain.
Consider an infinitesimal rectangle in the xy plane subject to shear strain. The rectangle becomes a parallelogram where is the displacement from the y axis in the x direction and is the displacement from the x axis in the y direction. The average shear strain is
Definition of engineering shear strain
where: is the angle before deformation and : is the angle at that same point after deformation.
Therefore describes the total deformation.
Moiré pattern(the Moiré effect can be used to measure strain)
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