Automatic Contacting Extensometry

The need for increased specimen throughput has created a demand for faster, more reliable, and more consistent materials testing equipment. Automatic contacting extensometers provide this capability by eliminating manual operator steps which can add time and introduce operator influence. 

Automatic contacting extensometry offers many benefits over traditional clip-on extensometers including:

• Consistent results regardless of operator due to automatic attachment and gauge length measurement
• More accurate results because the counterbalanced arms are virtually weightless and don’t bend the specimen
• More efficient testing because operators no longer manually attach and remove extensometers
• Measure strain through failure on materials ranging from composites to elastomers
• Increased uptime because it uses an optical measurement system which is resistant to damage

Application Range

• Measure strain properties of almost any material, including plastics, metals, composites, textiles, films, elastomers, paper, components, and bio-materials
• Metals tests including ASTM E8, ISO 6892, ASTM E517, and JIS Z2254
• Plastics tests including ASTM D638, ISO 527-2, ASTM D882, and ISO 527-3
• Composites tests including ASTM D3039 and ISO 527-4
• Elastomer tests including ASTM D412 and ISO 37
• Type of loading: tensile, flexure, compression

Principle Of Operation

The extensometer is automatically controlled via the system software. The software is setup with the desired lower arm position, and the gauge length. When the operator starts the test the motor driven arms are automatically moved to the correct position and attach to the specimen. The motor automatically disengages from the measuring arms, allowing the arms to freely travel with the specimen. The position of each arm is measured in real time using an optical linear scale with a resolution of less than 1 micron, ensuring the gauge length and strain are measured accurately. At the end of the test, the arms automatically remove themselves and return to the start position, ready for the operator to remove the broken specimen and test another.

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