Crazing has recently become of interest in composite materials having organic matrices, and the development of crazes has been suggested as a failure criterion in the fatigue testing of susceptible composites.

This paper reports the results of an experiment to find a practical means of detecting and monitoring the development of crazing during fatigue testing of fiber-reinforced epoxy matrix composite materials. A specimen of such material was strain-gaged with one 2-in.-long (0.051 m) foil gage, and with thirty 2/100-in.-long (0.508 mm) gages. The apparent strain of each gage was monitored during displacement control tension-tension fatigue testing.

The experimental results demonstrated that the maximum difference between apparent strains as measured by the small strain gages provided a sensitive means of detecting crazing. It was concluded that thirty small strain gages with appropriate instrumentation could provide a practical means of automatically detecting crazing during such fatigue tests of composite materials.