BS in Materials Engineering
Materials Engineering Department
A low velocity impact tower was donated to Cal Poly's Materials Engineering Department along with four fiber reinforced polymer matrix composites. The tower was set up in building 192 in the Mechanical Testing Laboratory. Improvements were made to the tower including adding velocity detection capabilities, making loose hardware inclusive, adding an extra tower arm for better consistency, adding a double jawed clamp for faster testing, and rerouting the tower's compressed air system to improve performance. A standard operating procedure was drafted, tested, and redrafted for impact testing composite panels. The four composite panels consisted of two quasi-isotropic 16 ply AS-1 carbon fiber reinforced polyetherether ketone (PEEK) matrix thermoplastic panels in a (45/90/-45/0)2s stacking sequence and two quasi-isotropic 16 ply TR50S carbon fiber reinforced TC27501 epoxy resin thermoset panels in a (45/90/-45/0)2s stacking sequence. The thermoset and thermoplastic panels were cut into twelve 152.4mm x101.6mm samples each and underwent impact testing on the tower per ASTM D7136 standards. 6.7 J/mm is the specified ratio of impact energy to specimen thickness for D7136 testing, and when coupled with the (thermoset) samples’ average thickness of about 2.47 mm equated to a 314.9 mm impactor drop height and lower. After impact samples were non-destructively inspected and displayed near a 0.8mm dent-depth with an 11.15mm maximum damage diameter. Damage types included a depression, splitting, cracking, fiber breakage, and delamination. The thermosets’ damage measurements and types were compared to the thermoplastic samples’ damages and found to be less damaged topically but more damaged internally.