SYMPOSIA PAPER Published: 01 August 2022
STP163820210042

Overview and Comparison of Noncontacting and Traditional Contacting Extensometers

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As optical systems and optical processing become more common and more affordable, some materials testing laboratories are replacing traditional displacement or strain measurement extensometers with noncontacting solutions. A wide variety of noncontacting measurement devices exist, but the differences between them often mean that the solutions are optimized for different measurement tasks. Some devices are focused on replacing existing contacting devices in monotonic tests, others in fatigue tests. Some devices are designed to provide richer, fuller strain data from the surface of the component under load, but they have difficulty providing the data in real time for control purposes. Some commercially available noncontacting systems are general purpose solutions and can be configured in multiple ways. Traditional contacting devices usually monitor the one-dimensional motion of contacting points, translating that motion to strain on one leg of a Wheatstone bridge, or motion of a magnet through a coil of wire, or charge capacitance between two plates. Modern, noncontacting devices can monitor motion in one, two, or even three dimensions. Some noncontacting systems monitor the motion of tens, hundreds, or millions of points on the component being monitored. Understanding the unique features and technologies of various devices will allow the researcher to choose the correct tool for the anticipated problem.

Author Information

Schwarzkopf, Erik, A.
MTS Systems, Eden Prairie, MN, US
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Details
Pages: 1–19
DOI: 10.1520/STP163820210042
ISBN-EB: 978-0-8031-7724-6
ISBN-13: 978-0-8031-7723-9