Underwater blast loading performance of composite panels
The purpose of this study was to expand the knowledge base, as well as observe the dynamic behavior, of water backed, E-glass/ vinyl ester (EVE) composites under water-backed underwater blast loading. Digital image correlation techniques were employed in this study. However, due to the non-linear effects from the refractive index of water traditional digital image correlation methodology must be modified. This was accomplished by taking images of a known calibration grid used submerged both in and out of water in the exact same position that the specimens would be in while testing. These image sets were then uploaded into MATLAB where a transformation matrix was obtained and subsequently implemented upon the experimental images. In doing so the specimen would be in its real world position and be undistorted from the refractive index of water. Small scale quasi-static tests using a screw driven material testing machine were conducted on polycarbonate discs in order to validate the modified digital image correlation (DIC) technique. It was found that using this method reduced the percent error between the strain values obtained from theory to those obtained through the modified DIC method to 20% or less in most cases. The dynamic experiments carried out on the EVE panels showed that decreasing the standoff distance to the charge increased the peak deflection the specimen undergoes linearly. Also it was seen that as the charge was moved closer to the specimen less delamination of the panel occurs and more resin matrix cracking is observed.^
Daniel Griffith Gracia,
"Underwater blast loading performance of composite panels"
Dissertations and Master's Theses (Campus Access).