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 composites. A median subtraction filter provided a trigger signal sensitive to emission events but not to noise. Values obtained for the strength 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 approximately constant at low stresses. Advantages of using acoustic emission are discussed.