Strain

The measure of deformation produced is called Strain. For the type of deformation as in (B) above, these can be the following kinds of strains.

Longitudinal or Tensile Strain

The change in length (Dl) to the original length (l) is called tensile strain.

Shear Strain

The change in area (DA) to the original area (A) is called shear deformation.

Note : For a small deformation angle of shear (q) is also considered as Shear Strain.

Figure 1

The figure shows Shear deformation of the rectangular block ABCDGEMN, due to displacement of face BCME to position B'C'M'E' when forces applied on top & base as shown. The angle q by which the force ABEG (or DCMN) is twisted to the position AB'E'G (or DC'M'N') is called angle of shear.

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Index

6.1 Definition of Elasticity
6.2 Types Of Deformations
6.3 Deforming and Restoring Forces
6.4 Strain and Stress
6.5 Hooke's Law
6.6 Elastic Modules
6.7 Strain Energy

Chapter 7