3540 Deflection Gages (Deflectometers) for Measuring Deformations in Three and Four Point Bend Test and Compression Tests

The Model 3540 from Epsilon is widely employed to measure deformations in three and four point bend tests, compression tests, and a variety of general purpose deformations. These strain gaged devices are provided with a magnetic base for easy mounting.

Deflection is measured with a single arm with an attached spherical contact tip that is similar to those on a dial indicator. The full bridge strain gaged construction provides an electrical output compatible with any electronics designed for a strain gaged transducer.

The magnetic base furnished with the gage can be mounted to the desired reference surface, whether round or flat. The tip can then be positioned to measure the deformation encountered while conducting the test. The magnetic base can only be used for both low and standard temperature testing. Additional support considerations are required for elevated temperature testing.

All models have a spring loaded arm that can break free in the event of excessive displacement, protecting the gage from damage. The upper arm exerts a small spring force against the specimen, which is sufficient to allow dynamic cyclic testing if desired, yet light enough in force to avoid impact on the test. Because minor variations in arm length can cause changes in the system calibration, the 3540 comprises of a mechanical stop for repeatable placement of the arm in situations where it becomes detached.

As standard, these units come with the arm set to measure downward deflections, when oriented in the upright position. The units can be used upside down or in any orientation. They may also be configured with the extensometer arm spring loaded downward. This should be specified if desired, and it must be noted that the measuring ranges listed are total displacement.

The Model 3540 extensometers are strain gaged devices, making them compatible with any electronics designed for strain gaged transducers. They are often connected to a test machine controller. The signal conditioning electronics for the extensometer is usually included with the test machine controller or may often be added.

In this case, the extensometer is delivered with the proper wiring and connector to plug directly into the electronics. Epsilon can offer a range of solutions for systems that do not have the required electronics. This enables the extensometer output to be connected to chart records, data acquisition boards or other equipment.

There are 36 Extensometer Models available in many thousands of variations. Epsilon’s focus of helping customers has led to the development of models to cover almost any test method.

Operation of these extensometers are verified to either ISO 9513 Standards or ASTM E2309 using in-house calibration systems that are calibrated with Epsilon’s laser interferometer system.

With Epsilon’s 20+ year history of service for the materials testing community, the company will be there to stand behind their products when the user’s critical application requires it.


The key features of the Model 3540 are as follows:

  • Includes high quality foam lined case
  • General purpose deflection sensor covers several test requirements
  • Meets ASTM and ISO accuracy classes as follows:
    • ASTM E2309 Class A, ISO 9513 Class 1: -001M, -004M, -006M, -005T, -015T, -025T
    • ASTM E2309 Class B, ISO 9513 Class 2: -012M, -025M, -050M, -050T, -100T, -200T
  • Supplied with an adjustable magnetic base for easy mounting
  • Spring loaded arm detaches to prevent damage from overtravel
  • All standard units have linearity of 0.25% of FS or better
  • Full bridge, 350 ohm strain gaged design for compatibility with nearly any test system
  • Rugged, dual flexure design for improved performance


The key specifications of the Model 3540 are as follows:

  • Linearity: ≤0.25% of full scale measuring range
  • Output: 2 to 4 mV/V, nominal, depending on model
  • Cable: Integral, ultra-flexible cable, 2.5 m (8 ft) standard
  • Temperature range: Standard (-ST) is -40 °C to +100 °C (-40 °F to 210 °F)
  • Operating force: 50 g typical
  • Excitation: 5 to 10 VDC recommended, 12 VDC or VAC maximum.


The following options are offered with the Model 3540 extensometers:

  • Arm orientation
  • Connectors to interface to almost any brand test equipment
  • Shunt Calibration

3540 Deflection Gages (Deflectometers) for Measuring Deformations in Three and Four Point Bend Test and Compression Tests


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.