Uniaxial and triaxial compression tests of silicon carbide ceramics under quasi-static loading condition.

Abstract

To establish mechanical properties and failure criteria of silicon carbide (SiC-N) ceramics, a series of quasi-static compression tests has been completed using a high-pressure vessel and a unique sample alignment jig. This report summarizes the test methods, set-up, relevant observations, and results from the constitutive experimental efforts. Results from the uniaxial and triaxial compression tests established the failure threshold for the SiC-N ceramics in terms of stress invariants (I 1 and J 2 ) over the range 1246<I 1 <2405. In this range, results are fitted to the following limit function (Fossum and Brannon, 2004) -4 , a 3 =11372 MPa, and a 4 =1.046. Combining these quasistatic triaxial compression strength measurements with existing data at higher pressures naturally results in different values for the least-squares fit to this function, appropriate over a broader pressure range. These triaxial compression tests are significant because they constitute the first successful measurements of SiC-N compressive strength under quasistatic conditions. Having an unconfined compressive strength of ~3800 MPa, SiC-N has been heretofore tested only under dynamic conditions to achieve a sufficiently large load to induce failure. Obtaining reliable quasi-static strength measurements has required design of a special alignment jig and loadspreader assembly, as well as redundant gages to ensure alignment. When considered in combination with existing dynamic strength measurements, these data significantly advance the characterization of pressure-dependence of strength, which is important for penetration simulations where failed regions are often at lower pressures than intact regions.3

Twisted-layer boron nitride ceramic with high deformability and strength

“…with introduction of plastic deformation. This value was two orders of magnitude higher than that of commercial hBN ceramics (0.26 MJ m −3 ) and significantly higher than those of other engineering ceramics, such as SiC (15 MJ m −3 ) and Mg partially stabilized zirconia (28 MJ m −3 ) 24,25 . Therefore, the TS-BN ceramic is an excellent candidate as an impact absorber.…”

The Use of Sphere Indentation Experiments to Characterize Ceramic Damage Models

“…The failure distributions used in the Kayenta model stem from the actual measured uncertainty in the characterization experiments. New experiments were completed at the Sandia National Labs 40 to obtain measurements of the failure surface under triaxial loading conditions, an area of the failure surface where no data were available.…”