Extension measurement two versions with different

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• Extension measurement: two versions with different measurement-travel ranges are available; in both ca- ses initial gage lengths are adjustable and extension pieces for greater gage lengths are available • Transverse strain extensometer: the digital clip-on extensometer measures the transverse strain with one measurement line • Biaxial measurement: Zwick biaxial clip-on extenso- meter for determining extension and change in width Fig. 1: Quick, easy, reliable handling Fig. 2: Biaxial digital extensometer 16
Analog clip-on extensometers Range of application These extensometers are clipped directly to the spe- cimen and are designed for strain measurement on metals and plastics. Their range of application covers fine strain and yield point (proof strength) measurement, as well as E-Modulus determination. These clip-on extensometers are available in manual or automatic clip-on versions and can be supplied with inductive or strain gage measuring systems. Inductive (analog) clip-on extensometer Inductive travel measurement involves moving a core and a coil of defined cross-section relative to each other, causing a change in inductance, which is propor- tional to the specimen extension. Specimen extension is transmitted via pairs of knife- edges attached to two sides of the specimen, each pair transmitting to the inductive measurement system in the extensometer. Advantages / Features • Very high measurement accuracy • The measurement leverage involved is very small as the measurement system is arranged very close to the specimen, giving enhanced measurement accuracy and reproducibility • Two measurement systems for averaging different edge-fiber extensions • The two measuring systems can optionally be evalua- ted separately via an additional sensor plug Strain-gage extensometers A strain gage is an electrical resistor attached to an in- sulating foil in a zigzag pattern perpedicular to the strain measurement direction. If the strain gage is stretched in the measurement direction, its electrical resistance increases. The specimen extension is transmitted via the sensor arms to mechanical elements equipped with strain gages, producing a defined deformation. Strain-gage clip-on extensometers are available for axial and transverse strain measurement in single or doublesided versions. Strain gages are also available in temperature-resistant versions for use in temperature chambers. Advantages / Features • Excellent linearity, ensuring reliable test results • Gage lengths are adjustable from 10 to 100 mm, enabling use for specimens of different sizes • Miniaturized, lightweight construction also makes them suitable for use with short specimens • The transverse strain extensometers are designed for use in conjunction with sensor-arm extensometers, or without an extensometer. They are specially designed for tests on metals, but can also be used to deter- mine Poisson’s ratio on fiber-reinforced laminates to ISO 527-1 Fig. 2: Strain-gage extensometer Fig. 1: Clip-on extensometer with optional counter-weight 17

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