Sandwich Core Shear and Rigid Cellular Plastic Shear Testing Extensometers – Model 3421
  • • Replaces homemade extension gages and LVDTs with a reliable, repeatable solution.
    • Simple clip-on design attaches in seconds.
    • May be left on through specimen failure when fixturing is used to constrain thickness expansion of the specimen.
    • Meets ASTM C273 requirements for extensometers.
    • Extensometer measuring arm has mechanical overtravel stops for durability.
    • Replaceable components for ease of repair.
    • Full bridge, 350 ohm strain gaged design for compatibility with nearly any test system.
    • Includes high quality foam lined case.

  • • Full bridge, 350 ohm strain gaged design for compatibility with nearly any test system.
    • All standard units have linearity readings of 0.20% or better.
    • Rugged, dual flexure design for improved performance.
    • Includes high quality foam lined case.
    • Breakaway arm to help prevent extensometer damage in the event of bolt failure.
    • Self-supporting on the bolt specimen typically without the need for centering or punch marks.

  • Options

    Connectors to interface to nearly any brand test equipment

    Shunt calibration module


  • Specification

    Excitation: 5 to 10 VDC recommended, 12 VDC or VAC max.

    Output: 2 to 4 mV/V

    Accuracy: ±5.0 mm/±0.200” measuring ranges:

    ≤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 ranges:

    ≤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℃ to +100℃ (-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 inch) minimum, 50-150 mm (2-6 inches) typica 


For measuring shear properties of sandwich cores to ASTM C273. Simple clip-on design attaches in seconds and provides repeatable test results.
Measuring Ranges:
±5 mm shear displacement
Temperature Range:
-265℃ to 200℃ with -LHT option
Key Features:
Sandwich core shear and rigid cellular plastic shear