Development of a low data event timer for monitoring an advancing crack in fracture

Monitoring the crack position and velocity in a fracture specimen can be difficult and laborious. In addition, the data storage requirements can be considerable depending upon the testing conditions. A low data event timer was developed to alleviate these problems. The timer generates a time-stamp when a circuit is broken. A continuous data record is not required, and this greatly reduces the data logging requirements. The test apparatus was applied to cantilever beams bonded with a structural epoxy and tested under different conditions, such as stable to unstable transitions and different temperature extremes. The results indicate that the approach eliminates problems associated with other types of crack measurement and greatly simplifies the measuring process.