Buffering Effect of Fiber Coating and Its Influence on the Proof-Test Load in Optical Fibers.

Since the tensile force during proof-testing of an optical fiber is applied to its coating, the load experienced by the glass fiber may be reduced due to the buffering effect of the coating. In this study such an effect is evaluated on the basis of an analytical stress model. It is shown that for any finite, even very great, interfacial compliance one can always choose a sufficiently long specimen in which the glass fiber would be loaded to practically the same level as in an infinitely long structure. It is also shown that the buffering effect may play an important role in short specimens but can be neglected for sufficiently long fibers. In these fibers the maximum load in the glass can be evaluated assuming that the external tensile load is applied to the entire cross-section of the coating/glass composite.