Accession Number : ADA626076


Title :   Mitigating Stress Waves by using Nanofoams and Nanohoneycombs


Descriptive Note : Final rept. 5 Dec 2011-4 Dec 2014


Corporate Author : CALIFORNIA UNIV SAN DIEGO LA JOLLA


Personal Author(s) : Qiao, Yu


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a626076.pdf


Report Date : 13 Feb 2015


Pagination or Media Count : 82


Abstract : In this ARO project, we had a remarkable finding: In dynamic indentation test, the indentation size of a silica nanofoam was smaller than in a solid silica; i.e. the former was effectively harder than the latter. All the samples were in the same amorphous silica phase; the porosity of all nanofoam samples was approximately 60%, and therefore, their mass density was only approximately 40% of that of solid silica. The experiment was conducted in a Split Hopkinson Bar (SHB) setup. A titanium striker impacted on a steel incident bar at approximately 8.5 m/s; the incident bar forced a hard hemispherical indenter into the silica sample. The silica sample was sandwiched in between the indenter and a steel transmitted bar.


Descriptors :   *FOAM , *NANOMATERIALS , *POROSITY , *SILICON DIOXIDE , ABSORPTION , AMORPHOUS MATERIALS , DAMPING , DYNAMICS , ENERGY DENSITY , EXPERIMENTAL DESIGN , HONEYCOMB STRUCTURES , IMPACT , MASS , MORPHOLOGY , PROTECTION , SCANNING ELECTRON MICROSCOPY , SHEAR STRENGTH , SHEAR TESTS , SPLITTING , STEEL , STRESS WAVES , TEST AND EVALUATION , TITANIUM , TRANSMITTANCE , VELOCITY


Subject Categories : Inorganic Chemistry
      Miscellaneous Materials
      Mechanics


Distribution Statement : APPROVED FOR PUBLIC RELEASE