Specimens are extended along the major longitudinal axis at a constant speed until either failure occurs, or it reaches a predetermined stress (load) or strain (elongation) value. The load and elongation sustained by the specimens are measured autographically during testing.

Numerous properties can be determined from this: 

  • Tensile strength and elongation at break
  • Stress and elongation at yield
  • Elongation at a given strength
  • Stress at a given elongation
  • Youngs' Modulus

Tensile Set

Tensile set (also referred to as Permanent Set) is the extension remaining after a specimen has been stretched and allowed to retract in a specified manner, expressed as a percentage of the original length.

Tensile set is important to many commercial rubber products that expand and contract in normal service. For example, seals and gaskets are usually stretched and must return to their original size in order to function properly in the specific application. This ability is expressed in tensile set.

Testing of rubber materials and products for tensile set involves applying force to the material to determine the residual deformation of the sample. After force has been applied, the deformation is partially permanent and partially recoverable. For this reason, the periods of extension and recovery must be controlled to obtain comparable results.

Common Standards

  • ASTM D412—Standard Test Methods for Vulcanized Rubber and Thermoplastic Elastomers—Tension
  • BS ISO 527—Plastics — Determination of tensile properties

About our Labs

Our experts can conduct standard tests or design custom protocols to meet your specific needs.

We have six universal testing machines which cover a calibrated load range of 1N up to 250kN. Our testing machines are supported by a variety of laser, video and the latest in contact extensometry. With environmental chambers, we can test over the temperature range of -50°C up to 200°C.

The presence of our extensive sample preparation facilities enable us to test a huge variety of materials and product forms.