Growth of corrosion cracks and long-term durability of brittle materials

Abstract

According to experimental results,thelong-termdurability ofbrittle materialsisgenerally definedby the development of corrosion cracks. It is supposed that the growth of corrosion cracks is governed by the kinetic equation corresponding to the reaction of decomposition of solid solution, and the stress intensity factor is responsible for the acceleration of the corrosion processes. Taking Griffit’s strength law into account, a fatigue criterion of a specimen with a crack is formulated. The reliability problem of complex mechanical systems composed of a number of elements with the crack type defects is also considered. As thereliability of asystemdepends onthereliability ofindividual elements and theway of theirconnection, the systems with the elements connected parallel and in series are considered. For each system the fatigue corrosion criterion is formulated and the corresponding fatigue curves are constructed. It is shown that the reliability of the system withparallel connected elementsis superiortothe reliability of a system with elements connected in series.

Keywords:

brittle materials, stress intensity coefficient, development of corrosion cracks, Griffit’s strenght criterion, long-term durability