Information on extensometers for deflection measurements

Manufacturers of Mechanical Testing


 Adelaide Testing Machines Inc.

 61 Advance Road Units 5 and 6

 Toronto, Ontario, Canada M8Z2S6

 Phone: 1-800-665-8817 (Canada/USA)

             1-416-234-0786 (International)

 Fax No.: 1-416-234-1369



 The EXT series of extensometers available from ATM include models for testing a wide

 range of materials including metals, plastics, composites and ceramics. Their designs

 incorporate a dual flexural arrangement which makes them very rugged and insensitive to

 vibrations. Many models are designed for application in both tension and compression.

 1) General Purpose EXT3542 Series

  Figure 1 shows a model from the EXT3542 series which are the standard series available

  from ATM. The 3542 series are a general purpose type of extensometer for axial tensile,

  compression, and cyclic testing. Gage lengths are available from 0.50 - 2.0" (10 - 50 mm)

  and with travel ranges from 5 -100% of gage length. These models come standard with a

  Quick Attach Kit also shown in Figure 1which makes it easy to mount the extensometer

  on the test specimen in seconds. The extensometer can also be mounted with the

  included springs or elastic bands. Figure 2 shows the dimensions of the different gage

  lengths of the EXT3542 series of extensometers.

  The EXT3542 extensometers are full Wheatstone bridge strain gage type of devices which

  are directly compatible with the computer controlled ATM series of tensile/compression

  testing machines such as the bench mounted TTS series and the floor mounted D series.

  The extensometer usually uses the second DC conditioner amplifier included with these

  machines. The standard temperature range of the EXT3542 series is from -40 C - 100 C

  (-40 F - 210 F).

  Major Features of the EXT3542 Series:

   - may be left on through specimen failure.

   - high accuracy with some models offering 0.1% linearity.

   - all models have travel in both tension and compression and can be used

     for cyclic testing.

   - rugged, dual flexure design for improved performance.

   - mechanical overtravel stops in both directions.

   - replaceable arms and spacers for ease of repair. This also allowschanging the

     gage length for different test requirements.

   - all units meet existing ASTM and ISO requirements for accuracy. All willmeet

     ASTM class B-1, except for the longest travel units, which meet class B-2.

   - hardened tool steel knife edges are easily replaced. A spare set comeswith

     each extensometer.

   -standard Quick Attach Kit for quick, one hand mounting to specimens. Works

     for both flat and round samples (flats to 0.5 x 1.0" (12 x 25 mm) and rounds

     up to 1 " (25 mm) diameter). Optional arms available for larger samples.

   - includes high quality foam lined case.

   - high and low temperature options extend operation from as low

     as -265 C (-450 F) up to 175 C (350 F).


      Sensor: Full Wheatstone strain gaged bridge design

      Output: 2 - 4 mV/V, nominal

      Excitation: 10 VDC typical, up to 15 VDC or VAC max

      Temperature range: Standard is -40 C (-40F) up to 175 C (350 F)

      Cable: Integral ultra flexible cable, 8 ft (2.5 m)

   Ordering Information:

         Model Number: EXT3542 - abcd - efg - hjk

            where abcd is the extensometer Gage length as follows:

                      Gage Length, "    abcd                Gage Length, mm      abcd

                            0.500            0050                         10.0                010M

                            0.640            0064                         25.0                025M

                            1.000            0100                         50.0                050M

                            1.400            0140                         80.0                080M

                            2.000            0200

            where efg is the extensometer travel length as follows:

                        Travel as % of Gage Length           efg              Linearity %

                                           +/- 5                         005                 0.10

                                          +/- 10                        010                  0.10

                                          +/- 20                        020                  0.15

                                          +/- 25                        025                  0.15

                                          + 50 / -10                   050                  0.15

                                          +100 / -5                   100                   0.15

            where hjk is the Temperature Range as follows:

                                      hjk                               Temperature Range

                                      LT0                  Low -265 C to 100 C (-450 F to 210 F)

                                      ST0                  Std -40 C to 100 C (-40 F to 210 F)

                                      HT1                  High -40 C to 150 C (-40 F to 300 F)

                                      HT2 High -40 C to 175 C (-40 F to 350 F)

   Other Extensometer Series 

  In addition to the EXT3542 series, ATM has available other types of extensometers for  

  applications which cannot be accommodated by the standard models in the EXT3542

  series. Please contact ATM for information on these other products.


  Typical EXT3542 Extensometer


        EXT3542 Extensometer

 with 0.500" or 10 mm Gage Length


        EXT3542 Extensometer

 with 1.000" or 25 mm Gage Length


        EXT3542 Extensometer

 with 2.000" or 50 mm Gage Length