Browsing by Subject "progressive failure"

The purpose of this thesis was to examine progressive composite damage models available within LS-DYNA and to correlate the results of these models with drop weight impact testing and with the non-destructive evaluation techniques of shearography, thermography, and ultrasonic testing. The secondary purpose of this study was to assess whether shearography and thermography provide an adequate less expensive replacement to ultrasonic testing. For this investigation, three models were chosen: Chang-Chang, Chang-Chang + Tsai-Wu, and a Faceted Failure Surface

Model. For the experimental impact testing, two sets of specimens were chosen: a 16-ply lay-up and a 32-ply lay-up of carbon fiber pre-preg material. The panel specimens were tested at various impact energies and the displacement and force history of the impactor were recorded. The models showed good correlation for the force history with the experiments. Furthermore, the 16-ply models correlated well with the displacement history. However, due the penalty method implementation, the 32-ply models did not show similar peak displacement output. The damage shown by the models was compared to non-destructive evaluation techniques. The shearography and thermography showed significantly less damage than the ultrasonic scans, and therefore do not provide an adequate replacement to ultrasonic scanning. In looking at correlation between the models and the non-destructive evaluation techniques, the faceted failure surface showed significantly more damage due to its elastic-plastic type formulation.