Snappy: A New Automated Testing Machine for Monitoring the Break Evolution Process during Single Fiber Fragmentation Test

A measurement of interfacial shear strength (IFSS) in fiber reinforced polymer (FRP) materials remains elusive after more than fifty years. This is due in part to the many sources of uncertainty, the time-consuming nature of the measurements, and the large amount of data required to statistically overcome that variability. A new device, called Snappy, was designed to improve upon previous attempts at automating the single fiber fragmentation test (SFFT) by increasing the image acquisition rate during traditional step-strain experiment. This enhancement allows for the investigation of the fiber break evolution during matrix relaxation periods and generates a record of the time, position, and local strain of each fragmentation event. Minimizing manpower is a key motivation for designing and building this new automated apparatus. A computer program was developed to process large image data sets acquired during SFFT and to automatically locate fiber fractures and store the processed information in a database. The automated fiber detection algorithm implemented in Snappy allows for the rapid acquisition of a record of the location of each break and the stress at which that failure occurred (tier 1 data), which is important for calculating the strength of the fiber at the critical length.