3421 Sandwich Core Shear Extensometers for Measuring Shear Properties of Rigid Cellular Plastics

The 3421 Sandwich Core Shear Extensometers from Epsilon are built to measure shear properties of rigid cellular plastics and sandwich cores. The simple clip-on design attaches within seconds and offers repeatable test results.

Epsilon extensometers are compatible with almost every brand of test equipment and can be supplied with the right connector to plug in directly, or supplied with a separate amplifier and conditioner.

Operation of these extensometers and all of Epsilon’s extensometers are verified to applicable standards such as ISO 9513 or ASTM E83 using in-house calibration systems. These systems are calibrated with Epsilon’s laser interferometer system.

Epsilon has over 20 years history of service for the materials testing community and will be there to stand behind their products when the user’s critical application requires it.

The Model 3421 extensometers measure shear strain of honeycomb and foam sandwich cores, as well as rigid cellular plastics. These extensometers can be used to measure 2% offset shear strength, shear modulus, and stress-strain curves prior to specimen failure.

The extensometer can be used to measure strain through specimen failure with specimen fixturing to restrict out-of-plane expansion. It may also be used for sandwich core shear fatigue testing.

The Model 3421 is suitable for testing to the following standards:

  • ISO 1922 Rigid cellular plastics - Determination of shear strength
  • ASTM C273 Shear properties of sandwich core materials
  • ASTM C394 Shear fatigue of sandwich core materials
  • EN 12090 Determination of shear behavior of thermal insulation products (single specimen test only)
  • DIN 53294 Testing of sandwiches; shear test

The extensometer mounts to the loading plates of the test specimen. It attaches to the specimen within seconds and can be used with compression or tension test fixture loading. The extensometer is modifiable to operate with a range of specimen widths and thicknesses, and includes an integrated scale for setting it to the specimen width.

The test operator has to clip the extensometer onto the specimen by squeezing two pads, placing the extensometer against the side of the specimen, and releasing the pads. The extensometer is self-supporting and does not require any further adjustments. It is removed prior to failure by unclipping.

As the Model 3421 extensometers are strain gaged devices, they are compatible with all electronics designed for strain gaged transducers. Quite often they are connected to a test machine controller and Epsilon will equip the extensometer with a compatible connector wired to plug directly into the controller.

Epsilon can provide many solutions for signal conditioning and connection to data acquisition systems, chart recorders, or other equipment, if a system is lacking the required electronics.


The key features of the 3421 Sandwich Core Shear Extensometers are as follows:

  • Replaces homemade extension gages and LVDTs with a reliable, repeatable solution
  • Simple clip-on design attaches within seconds
  • Can be left on through specimen failure when fixturing is used to restrain thickness expansion of the specimen
  • Complies with ASTM C273 requirements for extensometers
  • Extensometer measuring arm is provided mechanical overtravel stops for durability
  • Replaceable parts for ease of repair
  • Full bridge, 350 ohm strain gaged design for compatibility with almost any test system
  • High quality foam lined case is provided


The key specifications of the 3421 Sandwich Core Shear Extensometers are as follows:

  • Excitation: 5 to 10 VDC recommended, 12 VDC or VAC max
  • Output: 2 to 4 mV/V
  • Linearity:
    • ±5.0 mm/±0.200” measuring range:
      • ≤0.005 mm for displacement values <0.5 mm
      • ≤1.0% of reading for displacement values ≥0.5 mm
    • ±2.5 mm/±0.100” measuring range:
      • ≤0.001 mm for displacement values <0.25 mm
      • ≤0.4% of reading for displacement values ≥0.25 mm
  • Temperature range: Standard (-ST) is -40 °C to +100 °C (-40 °F to 210 °F)
  • Cable: Integral, ultra-flexible cable, 2.5 m (8 ft) standard
  • Specimen size: Thickness (including core and both loading plates): 20 - 75 mm (0.8 - 3.0 inches); width: 40 mm (1.5 ”) minimum, 50 - 150 mm (2-6 ”) typical


The following are the options available with the 3421 Sandwich Core Shear Extensometers:

  • Shunt calibration
  • Connectors to interface to nearly any brand of test equipment

3421 Sandwich Core Shear Extensometers for Measuring Shear Properties of Rigid Cellular Plastics


Other Equipment by this Supplier

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.