Fig. 11.

Representative plot of the longitudinal strain (E_xx) in a DB specimen measured optically (y-axis) and by grip displacement (x-axis). The median optical strain in the central region (the loaded region), which has grip-to-grip fiber continuity, is much greater than in the flared ends of the specimen (the shielded region), which contain severed fibers. See Fig. 9(c) for a diagram of these regions. The line of 1:1 correspondence between optical and grip strain is marked by a solid black line. Optical strain is approximately linearly correlated with grip strain up to and a little past the yield point.