| Popis: |
Mechanical-impact tests in liquid and gaseous oxygen atmospheres aid in the assessment of Al-Li alloys for their use in cryogenic tankage for Advanced Launch Systems. In these tests, a falling plummet-striker pin assembly impacts a small disc specimen. Compressive, radial shear, and tensile (hoop) stresses are imparted to the disc specimens. The combination of these stresses and the high strain rate results in unique deformation and fracture characteristics. These characteristics include adiabatic shear bands, micro-cracking, specimen splitting, specimen heating (local melting), radial deformation in preferred orientations, and shear lips at the specimen-striker pin interface. These deformation and fracture modes are described and compared for various tempers of Al-Li alloys 8090, 2090, 2095, and alloy 2219. Distinctions between the Al-Li alloys and alloy 2219 are discussed. |
