Model 3550 Axial/Torsional Extensometer - Epsilon Technology - #1

S550

Technology Corp

• Full bridge, 350 ohm strain gaged design for compatibility with nearly any test system.

• All standard units meet existing ASTM class B-1 and ISO 9513, class 0,5 requirements for accuracy.

• Rugged, dual flexure design for improved performance.

• Includes high quality foam lined case.

• Self-supporting on the specimen.

Epsilon Technology's axial/torsional extensometer was designed to directly measure the shear strain, y 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, R.

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

5 to 10 VDC recommended, 12 VDC or VAC max. 2 to 4 mV/V, nominal, depending on model <0.15%> of full scale measuring range, depending

The Model 3550 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. The standard sized model is self-supporting on the specimen, and works on specimens from 0.375 to 1.000 inches (9.5 to 25.4 mm). The included conical point contacts are made from tungsten carbide. Their unique design directly measures the surface shear strain angle, which allows operation on a wide range of specimen diameters without changing calibration.

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

Available options cover temperature ranges from -265 °C to 175 °C (the standard temperature range is -40 °C to 100 °C). Both inch and metric versions are available. A wide range of gage length and measuring ranges are available. Because these transducers are often used for specialized tests, contact Epsilon with your specific test needs.

^{y R} dL

on model

Temperature Range: Standard (-ST) is -40 °C to +100 °C (-40 °F to 210 °F)

Integral, ultra-flexible cable, 8 ft. (2.5 m) standard <30 g typical Less than 0.5%

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

Connectors to interface to nearly any brand test equipment

Shunt calibration module (see page 96)

Model 3590AT axial/torsional calibrator (see page 95)

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

y 2.50° ф 10°

Torsional Shear