THE MEASUREMENT OF FIBER STRENGTH PARAMETERS IN FRAGMENTATION TESTS BY USING ACOUSTIC-EMISSION

The Weibull shape and scale strength parameters of E-glass fibers were measured in situ by counting the number of acoustic emission events ( fractures) during the fragmentation of single-fiber E-glass/epoxy comp osites. A median subtraction filter provided a trigger signal sensitiv e to emission events but not to noise. Values obtained for the strengt h parameters are comparable to those obtained with optical microscopy. And, although there is considerable scatter, acoustic emission energy measurements tend to suggest that the recovery length is approximatel y constant at low stresses. Advantages of using acoustic emission are discussed.