Sahithyan's S1 -- Properties of Materials

Tensile Test

Stress-strain plot will be produced in the test.

Testing setup

Follows ASTM Standards E 8 and E 8M. (American Society for Testing and Materials).

The specimen: Tensile Test Specimen

Here

Gauge length
Initial diameter
Initial area

The setup: Tensile Test Setup

Test will be done until the specimen fractures. Results are converted to engineering stress and strain, and plotted.

Load cell

Measures the force applied to the specimen.

Extensometer

Used to measures the elongation (increase in length) in the specimen.

Necking

All deformation up to the maximum point is uniform throughout the specimen.

At this maximum stress, a neck begins to form – known as necking. All subsequent deformation is confined to this neck.

For brittle material

The σ-ε behavior of brittle materials cannot be assessed by a tensile test because:

Difficult to prepare test specimens
Difficult to grip brittle materials without fracturing them

Hence, fracture strength is specified for engineering design purposes. Tensile strength is calculated from its modulus of rupture (MOR) or flexural strength value.