N. T. Younis*, B. Kang
The Journal of Mechanical Science and Technology, vol. 25, no. 1, pp.163-169, 2011

Abstract : Choosing the right strain gage for a measurement application requires selecting gages with the right characteristics for the job. In general, the strain gage is to be used to measure the strain at the center of the gage, but it inherently underestimates the peak strain when it is mounted in high stress gradient areas. This paper concerns itself with the averaging effects of a strain gage along gage filaments. The approach is unconventional in dealing with the orientation and size of the gage. The results provide insight into the averaging effect and selecting gages for measuring strains in areas of steep strain gradients. Dimensionless curves which can be used to estimate errors as well as enhance hole-drilling method results are presented. Practical recommendations are made for selecting gages for high strain gradient measurements.

Keyword : Average strain; Experimental stress analysis; Strain gage; Stress concentration factor