Assessing the Difference in Measuring Bolt Stress: A Comparison of Two Optical Fiber Sensing Techniques

Figure 13

Axial stress obtained by the FBG and PPP-BOTDA sensors and its ratio, located at (a) 4 cm, (b) 29 cm, (c) 54 cm, and (d) 79 cm from the orifice on the bolt.

(a)

(b)

(c)

(d)