MODEL 3550HT High Temperature
Axial/Torsional Extensometers (1200°C or 1600°C)

Designed for simultaneously measuring axial and torsional deflections on specimens tested in axial/torsional machines. The 3550HT axial/torsional extensometers are available in versions rated to 1200 °C (2200 °F) or 1600 °C (2900 °F). These are externally supported and use a special bracket for load frame mounting.

The high temperature 3550HT is for use in materials testing furnaces and with induction heating. The units are provided with high purity alumina rods (to 1200 °C) for specimen contact. Silicon carbide rods are used to 1600 °C.

This model extensometer is most often used on round specimens tested in bi-axial test machines capable of simultaneous axial and torsional loading. The extensometer is often customized for particular applications. All units are capable of bi-directional displacement, so they may be used for cyclic testing under fully reversed loading conditions.

All models are designed specifically to minimize crosstalk between axes and to provide high accuracy measurements. All feature the strong, dual flexure design common to other Epsilon extensometers.

Because these transducers are so often used for specialized tests, contact Epsilon with your specific test needs. We can then recommend the ideal configuration for your test requirements.

The Model 3550HT 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. The signal conditioning electronics for the extensometer is typically included with the test machine controller or may often be added. In this case the extensometer is shipped with the proper connector and wiring to plug directly into the electronics. For systems lacking the required electronics, Epsilon can provide a variety of solutions, allowing the extensometer output to be connected to data acquisition boards, chart recorders or other equipment.

Features

• Full bridge, 350 ohm strain gaged design for compatibility with nearly any test system.
• Standard units meet existing ASTM class B-1 requirements for accuracy in axial measuring range. A calibration certificate is included. ISO 9513 class 0,5 calibrations are available upon request. All standard units have linearity readings of 0.20% or better in torsion.
• All units come with either high purity alumina ceramic rods (1200 °C) or alpha grade silicon carbide rods (1600 °C).
• Rugged, dual flexure design for improved performance.
• Includes high quality foam lined case and a spare set of ceramic rods.

 

Epsilon’s axial/torsional extensometer was designed to directly measure the shear strain, γ, shown in the figure. This design allows the correct determination of the shear strain without having to know the radius of the specimen being tested, R₁.

The shear strain is related to the angle of twist (a commonly referenced parameter in torsion testing), φ, by the following relationship:

For extensometers that measure φ directly instead of γ, corrections need to be made for every different specimen diameter tested and for axial strain to correctly determine the shear strain.

The two examples below show the variation of the angle of twist versus a change in specimen diameter relative to the constant resulting shear strain:

 

  CERTIFIED

Specifications

Excitation: 5 to 10 VDC recommended, 12 VDC or VAC max.
Output: 2 to 4 mV/V, nominal, depending on model
Linearity: ≤0.15% of full scale measuring range, depending on model
Temperature Range: Standard (-ST) is to 1200 °C (2200 °F), optional (-HT) 1600 °C (2900 °F)
Cable: Integral, ultra-flexible cable, 8 ft (2.5 m) standard
Operating Force: <30 g typical
Crosstalk: Less than 0.5%

 

Options

• Model 2050 constant temperature water re-circulating bath
• High temperature option (-HT suffix) for use to 1600°C
• Connectors to interface to nearly any brand test equipment

 

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