Analysis of exit-ply temperature characteristics and their effects on occurrence of exit-ply damages during UD CFRP drilling

摘要

This paper focuses on the analysis of exit-ply temperature characteristics and the occurrence of exit-damages during drilling of UD CFRP. Different diameter drills are used to reveal their effects on temperature variation, cutting mechanism and damage modes. The results show that exit-ply temperature is strongly dependent on the interaction between tool-workpiece system. In particular, an significant factor to affect the peak temperature is the location of unruptured region when main cutting edges act on exit-plies, which will result in high temperature appearing along hole edge at theta similar to 0 degrees. The two-dimensional maps of high temperature along borehole edge are drawn at a continuous change of fiber cutting angles, based on which the dependences of exit-damages on the cutting temperature variations are discussed for the first time. The effects of high temperature on the exitply hole wall damages are concluded by examining the micrographs. And the width of loose surface near the hole-exit is identified to represent the functioning range of the excessive temperature. Moreover, the effects of high temperature on the exit-delaminations are analyzed by the adjusted delamination factor (F-da) at various drilling parameters.