Calibration techniques for extensometry: Possible standards of strain measurement
- Measurements Group, Inc., Raleigh, NC (United States)
The search for an adequate reference strain measuring technique for use in the materials testing laboratory has spanned several decades. Early methods relied on properly calibrated extensometers. Two examples are Tuckerman's Optical Strain Gage and Bergqvist's highly refined inductive and strain gage based extensometers. Length standards were used to calibrate these devices. Initially, mechanical displacement mechanisms were used as extensometer checking devices, but with the advent of lasers, the Michelson interferometer has become a dominant displacement measuring tool. Advances in stabilizing hardware and electronic detectors have led to the availability of Michelson systems with a resolution better than 5 nm. Microelectronic manufacturing techniques have been used to replicate the entire Michelson systems on a silicon ship. Advances in detector technology have also led to interferometric linear encoders with resolutions commensurate to classical interferometers. New techniques are being developed that can report strain and do not require initial calibration by displacement measuring instruments. This paper reviews some of the more interesting approaches from the past, analyzes some current methods being investigated, and comments on possibilities for the future concerning the difficult task of finding a suitable calibration technique for use with strain measuring devices.
- OSTI ID:
- 5598369
- Journal Information:
- Journal of Testing and Evaluation; (United States), Journal Name: Journal of Testing and Evaluation; (United States) Vol. 21:6; ISSN JTEVAB; ISSN 0090-3973
- Country of Publication:
- United States
- Language:
- English
Similar Records
A mechanical extensometer for high-temperature tensile testing of ceramics
Principles of calibrating the dual-recycled GEO 600