21 March 2017

Tensile test

A tensile test is one of the simplest and basic tests and determines the value of a number of parameters concerned with mechanical properties of materials like strength, ductility, toughness.

Some other information can be obtained by this test are following below :

  • Proportional limit
  • Elastic limit
  • Modulus of elasticity
  • Yield strength
  • Ultimate tensile strength
  • Modulus of resilience
  • Modulus of toughness
  • Percentage elongation
  • Percentage reduction in area
The specimen used in a tensile test is illustrated in the figure below :

Tensile test

The shape and dimensions of this specimen are standardized and confirm to 
IS 1608:1972. 
The cross-section of the specimen can be circular, rectangular or square.
The standard gauge length is given by l0.

Procedure :

In the tensile test, the specimen is subjected to axial tensile force, which continues increasing and corresponding to that deformation is measured.
The specimen is mounted on the machine and gripped in the jaws. It is subjected to tensile stress which is increased by increments. After each increment, the amount by which the gauge length lincreases and deformation of gauge length are measured by an extensometer.

This procedure of measuring the tensile force and corresponding deformation continued till fracture. 

This results of a tension test are expressed by means of a stress strain diagram.

Uniaxial tensile testing is the most commonly used for obtaining the mechanical characteristics of isotropic materials. For anisotropic materials, such as composite materials and textiles, biaxial tensile testing is required.