A novel four-point bend test for strength measurement of optical fibers and thin beams. II. Statistical analysis

In the first part of this work, a novel implementation of the well-known four-point bend test is described that determines the strength of thin beams and optical fibers by measuring the loading pin displacement, rather than the applied load. This paper extends the analysis of the nonlinear bending behavior to account for the stochastic nature of strength. A statistical analysis is presented that determines the effective tested length in bending and the tension to bending strength ratio. Results are given for both surface and volume flaws as well as for specimens of both circular and rectangular section. Strength measurements on a deliberately weakened silica optical fiber are consistent with the predictions of the analysis.