Evaluation methods for the hoop strength of small-sized tubular ceramic components

Miniaturized test methods were developed and applied to measure the hoop strength of small tubular components. A diametrical loading method and an internal pressurization method using elastomeric insert were adopted in the development of testing methods. Detailed analyses to assess these testing methods were attempted by using theoretical solutions and finite element analysis for stress distributions and the characteristics of the Weibull statistics. To demonstrate the applicability of the test methods, commercially available alumina tubes and miniature silicon carbide coatings from surrogate nuclear fuel particles were tested and their fracture strength distributions were analyzed with Weibull statistics. The size scaling relationship on the fracture strength was investigated by correlating with effective surface area. Furthermore, the applicability of the testing methods was discussed in terms of multiaxial stress fields, altered stress distribution by flattened loading contact, and availability of insert, focusing on high-temperature applications.X111sciescopu

Elemental compositions of comet 81P/Wild 2 samples collected by Stardust

We measured the elemental compositions of material from 23 particles in aerogel and from residue in seven craters in aluminum foil that was collected during passage of the Stardust spacecraft through the coma of comet 81P/Wild 2. These particles are chemically heterogeneous at the largest size scale analyzed (similar to 180 ng). The mean elemental composition of this Wild 2 material is consistent with the CI meteorite composition, which is thought to represent the bulk composition of the solar system, for the elements Mg, Si, Mn, Fe, and Ni to 35%, and for Ca and Ti to 60%. The elements Cu, Zn, and Ga appear enriched in this Wild 2 material, which suggests that the CI meteorites may not represent the solar system composition for these moderately volatile minor elements