How to Perform a Tensile Strength Test on Elastomers According to ASTM D412
Written by Kayla Thackeray
This guide is designed to introduce you to the basic elements of an ASTM D412 tensile test, and will provide an overview of the materials testing equipment, software, and samples needed. However, anyone planning to conduct ASTM D412 testing should not consider this guide an adequate substitute for reading the full standard.
What Does it Measure?
ASTM D412 measures the elasticity of a material while under tensile strain, as well as its behavior after testing when the material is no longer being stressed. ASTM D412 is conducted on a universal testing machine (also called a tensile testing machine) at a rate of 500 ± 50 mm/min until the specimen fails. Though ASTM D412 measures many different tensile properties, the following are the most common:
- Tensile strength – the maximum tensile stress applied in stretching a specimen to rupture.
- Tensile stress at a given elongation – the stress required to stretch the uniform cross-section of a test specimen to a given elongation.
- Ultimate elongation – the elongation at which rupture occurs in the application of continued tensile stress.
- Tensile set – 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.
Please note that ASTM D412 does not apply to testing hard, low-elongation elastomers such as ebonite. Those needing to test ebonite and hard plastics should refer to ASTM D638.
Tensile Testing System
Most ASTM D412 testing is performed on a tabletop universal testing machine with a variety of accessories that can be configured to properly perform an ASTM D412 tension strength test for elastomers and rubber.
A standard package would include a 3400 Series test system, an XL long travel extensometer, and a pair of manual roller grips. This system is excellent for small-to-midsize elastomer manufacturing companies, or for those buying their first D412 system. A more advanced and efficient system is the 6800 Series test system with an AVE 2 non-contacting video extensometer and a pair of 2712 Series pneumatic side action grips with an advanced air kit. This system is the world standard for tire manufacturers and large multinational elastomer manufacturers. For customers that demand high throughput, Instron's multi-station testing systems are the answer and can test as many as five samples simultaneously. A sample ASTM D412 test setup is pictured below.