Environmental Exposure of Boron-Epoxy Composite Material
Abstract
Boron-epoxy composite material (Textron 5521 F/4) was exposed at two tropical exposure sites within Australia for a period of about 3.5 years to evaluate the effects of outdoor exposure on mechanical properties. Specimens were exposed to three exposure types; fully exposed, covered and shaded. Moisture contents of 0.85% at Tindal N.T and 1.07% at AMRL-Q, Innisfail, QLD were found after about 3.5 years for the shaded and covered exposure conditions. Fully exposed specimens had about 20% less moisture. Mechanical tests were then performed in +/- 45 deg in-plane shear at both room temperature and 60 deg C to assess the effects of moisture on the matrix. The chord shear modulus was also determined in some cases. The results indicated that no significant changes in shear strength occurred at room temperature or 60 deg C due to outdoor exposure. The peak shear stress is about 15% lower when tested at 60 deg C compared to those tested at room temperature. The chord shear modulus values were subject to scatter but did not reveal any deterioration in material performance. An accelerated laboratory conditioning scheme to produce a 1% moisture level in the composite was also devised which allowed an equilibrium moisture level to be established in eight ply boron-epoxy specimens after only six weeks. This study found no evidence that absorbed moisture is likely to degrade the strength of boron-epoxy repair patches used on RAAF aircraft when tested at room temperature and 60 deg C.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 2000
- Accession Number
- ADA385731
Entities
People
- Roger Vodicka
Organizations
- Defence Science and Technology Group