In spite of his great applied interest, the tensile strength of brittle
materials, and chiefly that of ceramics, is difficult to measure directly by
classical tensile tests. This results from the difficulties induced both by
the samples machining and their grip on the testing machine. So, it is
common to perform indirect determinations on the basis of strength values
obtained in 3 or 4 points bending tests on prismatic samples.
In the case of massive or hollow cylindrical samples, the diametral
compression tests seem to be the best measurement technique, but these tests
require refined experimental approach to lead to significant results. In
order to characterise these care, two original experimental devices, one
dedicated to massive cylinders, the other to hollow cylinders, have been
built. The comparison of results thus obtained with those given by the
classical bending tests permits to specify the validity and the limits of
the techniques here developed.