Low velocity impact damage in glass / polyester composite sandwich panels

Impact resistance of glass/polyester facesheets/PVC foam core sandwich structures was primarily assessed in terms of skin-/core bonding efficiency using two types of adhesives and bonding with uncured resin. Also, the air-coupled ultrasonic C-scan technique was estimated as a means of characterizing impact damage size in sandwich structures. The following observations were made. The impact damage size estimated by visual inspection was much more extensive in all samples, which is due to the C-scan images showing only the overlapping delaminations area directly under the impact site, whereas the visual inspection of the laminate surface and macroscopic observations of the sample section show the extent of the largest, single delamination. The least extensive damage size was found in the two-phase high-density adhesive samples showing also the highest tendency for core cracking. In contrast, the “pinkglue” adhesive, which is low-density due to the presence of the microspheres provides greater local flexibility which prevented core craking.