Dynamic fragmentation of ferroelectric ceramics using the torsional Kolsky bar

Abstract

This paper studied the dynamic loading and subsequent fragmentation of four different load zirconate titanate (95/5 PZT) ferroelectric ceramics using a torsional Kolsky bar apparatus. Solid cylinders of the four materials were loaded in torsion at shear strain rates in the range 10/sup 2/ to 10/sup 3/s/sup -1/. Using the strain gage recordings of the incident, reflected and transmitted pulses, the energy required to fragment the specimen was determined for each test. In addition, the fragments resulting from each test were collected and analyzed by various technciques to determine their mass and size distributions. Results show some differences in particle distributions between the different batches of material. However, there is a more significant and consistent difference between the dynamic strength (as measured by the maximum shear stress) and the fragment mass distributions of the virgin material and the pressure depoled material, despite the fact that no differences were detected in the energy of fragmentation. Using earlier analytical results which relate the local kinetic energy of a potential fragment to the surface energy required to create that fragment, a relationship between the distribution of fragments from a test and material properties was derived. Results of tests on PZT as well asmore » other materials such as oil shale, graphite, uranium dioxide and glass indicate a good correlation between the fragment distribution parameter, n, and material properties as predicted by the theory. Finally, the results are analyzed to determine the potential effects of internal stresses on the dynamic strength of the material and its fragmentation characteristics. « less

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