Strength Degradation of Filament-Wound Graphite/Epoxy Tubes Due to Either Impact Damage or Fabrication Defects
AEROSPACE CORP EL SEGUNDO CA
Pagination or Media Count:
Two test series were conducted to assess the strength degradation of filament-wound graphiteepoxy tubes caused by impact damage or fabrication defects. The defects were either helical wrinkles or a hoop wrinkle inside the tube walls. The baseline tube configuration had a nine-ply 10 deg, -10 deg, 90 deg3 lay-up, with the exception of one tube having a 15 deg, -l5 deg, 90 deg, 90 deg3 stacking sequence. The latter lay-up configuration was to induce helical fiber-dominated failure. The tubes were subjected to either pneumatic or hydrostatic internal pressure, creating a biaxial stress state in the tube walls. The test results show that the burst pressure decreases significantly with increasing impact force for impact-damaged tubes. For impact loads of 823 to 1470 N 185 to 330 lb, the burst pressure dropped by 24 to 32, respectively, compared to those with no impact damage. Most failures initiated at the impact locations. Some originated from locations other than the impact sites. For the wrinkle-defect specimens, minor helical wrinkles had no measurable effect on the burst pressure. More severe helical wrinkles decreased the burst pressure by 8. Hoop wrinkles caused a significant degradation in strength 14 on average.
- Laminates and Composite Materials
- Pumps, Filters, Pipes, Tubing, Fittings and Valves