Averaging Axial Extensometers – Model 3442AVG

This all-purpose averaging axial extensometer is used in tension or compression to measure Young’s modulus, offset yield, and strain to failure. It is compact and lightweight. Gauge length is set automatically for fast specimen mounting.

38 EXTENSOMETER MODELS are available in many thousands of variations. Our focus on helping customers has led to the development of models to cover nearly any test method.

Operation of these, and all of Epsilon’s extensometers, are


using in-house calibration systems that are calibrated with Epsilon’s laser interferometer system.


to the materials testing community, you know we will be there to stand behind our products when your critical application requires it.

The Model 3442AVG is optimized for high-accuracy tension and compression testing. It measures strain simultaneously on opposite sides of the specimen to average out specimen misalgnment while measuring axial strain. The averaging capability is useful for measuring Young’s modulus per ASTM E111, properties of composite materials per ISO 527 and ASTM D3039, and compression of metals per ASTM E9. It is compact, lightweight, and may be used through specimen failure with most materials. It is fatigue rated and may be used in strain control.

The extensometer sets its gauge length automatically when it is mounted on the specimen. This feature improves repeatability, reduces operator errors and saves time. Just mount the extensometer and it will be at its gauge length and ready for testing.

This extensometer’s output can be configured in two ways: with a single output for average strain measurement, or with separate outputs for measuring strain separately on opposite sides of the specimen with two strain channels. The configuration with two outputs can be used during test setup or during the test to measure specimen bending (strain uniformity) caused by misalignment or specimen machining imperfections.

Due to its compact size, the 3442AVG is not compatible with transverse extensometers. To measure Poisson’s ratio, the Model 3442AVG may be used in combination with a transverse adhesively bonded strain gage, or other other extensometers may be used such as Model 3560BIA or Model 3542 in combination with Model 3575.

Model 3442AVG extensometers are strain gaged devices, making them compatible with any electronics designed for strain gaged transducers. Most 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. For systems lacking the required electronics, Epsilon can provide a variety of solutions for signal conditioning and connection to data acquisition systems or other equipment.

Download Data Sheet

  • May be left on through specimen failure with most materials.
  • Full bridge, 350 ohm strain gaged design for compatibility with nearly any test system.
  • Simple clip-on mounting with automatic gauge length setting.
  • Smaller than other averaging extensometers – fits in narrow spaces.
  • Measures average strain in both tension and compression, and can be used for cyclic testing.
  • Measures opposite sides of the specimen to average out misalignment.
  • When configured with separate strain outputs, can be used to calculate average strain and % bending.
  • Knife edge mounting allows mounting on round or flat specimens – much easier to mount than designs using conical points, especially on thin flat specimens and round specimens.
  • Quick and easy specimen size adjustment with integrated scale and tool-free adjustment.
  • All models have mechanical overtravel stops in both directions. Hardened tool steel knife edges are easily replaced. A spare set comes with every extensometer.
  • Includes the Epsilon Shunt Calibration System for on-site electrical calibration.
  • Rugged, dual flexure design for strength and improved performance. Much stronger than single flexure designs, this also allows cyclic testing at higher frequencies.
  • Includes high quality foam lined case and spare set of tool steel knife edges.

Download Data Sheet

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

Output: 2 to 4 mV/V, nominal, depending on model

Accuracy: Standard configurations meet ASTM E83 class B-1 and ISO 9513 class 0,5 requirements for accuracy. A test certificate is included.

Linearity: ≤0.15% of full scale measuring range, depending on model

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: Works with samples 0.25 to 25 mm (0.01 to 1.0 inch) width or diameter

Operating Force: 30 to 50 g typical

Maximum Operating Frequency: 50 to 100 Hz typical



Download Data Sheet

  • One averaged output or two separate left/right outputs
  • Connectors to interface to nearly any brand of test equipment
  • Expanded temperature ranges from -270 °C to +200 °C (-454 °F to +400 °F)

Download Data Sheet

Product Videos

Unidirectional composite tensile test through failure
Setup instructions for the Model 3442AVG extensometer

Ordering Information

Click table options to configure

Gauge Length i
mm or inches #
10.0 mm -010M 010M
12.5 mm -0125M 0125M
25.0 mm -025M 025M
50.0 mm -050M 050M
0.500 in -0050 0050
1.000 in -0100 0100
2.000 in -0200 0200
Measuring Range i
extension #
±0.5 mm -005M 005M
±1.0 mm -010M 010M
+2.5/-1.0 mm -025M 025M
±0.020 in -002T 002T
±0.050 in -005T 005T
+0.100/-0.050 in -010T 010T


Temperature Range
degrees #
-270 °C to 100 °C (-454 °F to 210 °F) -LT LT
-40 °C to 100 °C (-40 °F to 210 °F) -ST ST
-40 °C to 150 °C (-40 °F to 300 °F) -HT1 HT1
-40 °C to 200 °C (-40 °F to 400 °F) -HT2 HT2
-270 °C to 200 °C (-454 °F to 400 °F) -LHT LHT

Model Number:  3442AVG_ _ _ __ _ _ __ _

Selected Tensile Measuring Range: _ _ _ _

Specify one or two outputs when ordering.

Model 3442AVG Available Versions: Any combination of gauge length, measuring range and temperature range listed above is available. Other configurations may be available with special order; please contact Epsilon to discuss your requirements.

Example: 3442AVG-050M-025M-HT2: two outputs, 50.0 mm gauge length, +2.5 mm/-1.0 mm measuring range, HT2 temperature option (-40 °C to 200 °C)


If your unit is in need of service, calibration or repair, initiate the RMA process with us and we will be happy to assist.

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