Extensometer

Extensometer Points : Extensometer An extensometer is an instrument or device by which the changes in has of specimen under test can be precisely measured. Extensometer with different design to available; here we shall discuss only one of the types i.e. Ewing’s Extensometer. The Ewing’s extensometer s fined to a test piece L by two parts screws attached to the clamping pieces M arid N. the top horizontal piece passes through the N and is fitted with a micrometer screw at left end and on the right end a rod is pivoted.
When the tensile test is carried on the test piece, it would be stretched and the movement the rod is measured by means of a microscope fixed in the line with clamp M and focused a fine cross wire on the rod. The displacement is read on the micrometer scale in the micro eye piece. The movement of the rod is twice the extension produced in the test piece.