A High-frequency High-temperature Optical Strain/Displacement Gage

作者：Sharpe W N^*

来源：Experimental Mechanics, 2010, 50(2): 227-237.

DOI：10.1007/s11340-009-9278-x

• Optical strain measurement
• High cycle fatigue
• High temperature testing
• Short gage length
• Interferometry

This paper describes an optical method for measuring strain or crack-opening displacement at high frequencies (20 kHz) and high temperatures (590A degrees C) on a near-real-time basis. Two small reflective markers are placed on a smooth specimen or across a crack. When illuminated with a laser, interference fringes are generated; their motion can be monitored with photomultiplier tubes. The data acquisition system acquires 200 points per 50 microsecond cycle. These are processed, displayed, and stored at a rate of 25 Hz. Applications are in the general area of very high cycle (10(9) cycles or more) fatigue. Demonstration tests at 20 kHz at room temperature with a strain range of 0.45 percent and at 590A degrees C with a range of 0.2 percent are presented along with room temperature displacements up to 0.7 A mu m across the center of a 1.4 mm long crack.

• 出版日期2010-2