United Extensometer's are available in various configurations depending on your specific test requirement. Gauge length and expected strain rate are the two primary factors used to determine which specific model will be required. Please specifiy these parameters when requesting a quote. 

Gauge Length

Extensometer gauge length is the distance between the extensometers initial measuring points on the specimen. If you are using a test standad, check the standard for extensometer gauge length requirements. Many standards specifiy specimen dimensions and a matching gauge length. Many specimens also have a reduced section length that is designed to be greater that the extensometers gauge length.

Strain Rate/Measuring Range

Measuring range is the measuring capacity of the extensometer in tension or compression in units of % strain, maximum extension, or maximum deflection. When measuring range is in units of % strain, this means the maximum extension as percentage of the gauge length. A common extensomer requirement would be to have a Gauge Length of 1" (Starting distance between the two clips) and an expected strain rate of 0.5, or 50%, but is always best to reference the testing standard for guidance.

*Extensometers are generally not interchangeable between the different manufacturers of test frames. They are designed to be used with one specific manufacturer.

Features & Benefits

Types of Extensometers

United offers a wide variety of extensometers and choosing the appropriate one is highly dependent upon the material you are testing and the properties of that material. There are several different categories of extensometers;

Averaging Extensometer

·  Measures from both sides of sample and averages the results.
·  Available in gage lengths of 0.5”, 1”, 1.4” or 2”.
·  Built-in overload protection.
·  Automatic gage length setting.
·  Class B-1 extensometers.
·  High temperature version (up to 350°F) is also available.

Biaxial Extensometer

Specifically designed to determine Poisson’s ratio. Unit weighs only 40 grams. Meets ASTM E-83, Class B-1 and B-2 specifications. High temperature version (up to 350°F) also available.

High Elongation Clip-on Extensometer

Designed for easy, clip-on attachment to the sample. Available in gage lengths of 0.5”, 1”, or 2”. With measurement capabilities to 100% sample elongation, the unique extensometers also features built-in overload protection. These extensometers can be configured for use on either round or flat samples. Each unit is factory-calibrated to ensure that it meets ASTM E-83, Class B-2 accuracy specifications. High temperature version is also available.

High Elongation Frame Mounted Extensometer

To cover the needs of high elongation elastometric samples testing, United offers the High Elongation Frame Mounted Extensometer. Mounted on the load frame column cover via two articulating arms, the extensometer can be moved up or down, or swung completely out of the way during non-use periods. Along with a resolution of 0.005”, accuracy of ±0.01” or 0.5%, whichever is greater, and a usable range of 20 inches, the extensometer also features quick release adjustable clamps easily changed from 1 to 2-inch gage lengths, and a unique air dampening counterbalance system. Designed for use in a room temperature environment, the extensometer can be used in conjunction with any of a variety of strain measuring recording instrumentation.

Non-Contact Extensometers (Video & Laser)

These types of extensometers use a high resolution camera system (Video Extensometer), or a laser light bounced off the sample (Laser Extensometer) to measure the strain on sample being tested. Both systems are highly accurate and ideal for situations when a non-contacting extensometer is required.

Learn more about United's Laser Extensometer