Measurement of crack propagation in polymer pipes with embedded optical fibers

摘要

Abstract: A specially designed optical time domain reflectometer was used to measure the speed of propagation of rapidly running induced cracks along high density polyethylene pipes. Optical fibers were wound in a helical form around each pipe sample. Upon arrival, the propagating crack succesively broke and shortened the fibers; thereby the travel time of a reflected light pulse was reduced. The time dependent lengths of the fibers indicated the position of the edge of the crack. With this method crack speeds in the range of 100 m/s to 200 m/s were measured. The results agree well with those obtained by a conventional method. The fiber optical measurement even allowed to determine the form of the crack path. !5