Mechanical Properties of Solids. Strain. The ratio of change produced in the dimensions of a body by a system of forces or couples, in equilibrium, to its original dimensions is called strain. .
The ratio of change produced in the dimensions of a body by a system of forces or couples, in equilibrium, to its original dimensions is called strain.
Strain is of three types depending upon the change produced in a body and the stress applied. The three types of strain are
(ii) Volume strain
(iii) Shearing strain
Longitudinal Strain is the ratio of the change in length of a body to the original length of the body.
If L is the original length of a wire or a rod and the final length of the wire or the rod is L + L . under the action of a normal stress, the change in length is L.
Longitudinal Strain = Change in length / Original length
The strain produced by a hydraulic pressure is called volume strain. It is defined as the ratio of change in volume (ΔV) to the original volume V.
Volume strain = Change in volume / Original volume
Shearing strain is the ratio of relative displacement of the faces Δ x to the length of the body (cylinder) L.
where θ is the angular displacement of the cylinder from the vertical.