A CONTROLLED FLAW TECHNIQUE FOR LIFETIME CHARACTERIZATION

A new technique for studying the lifetime characteristics of brittle m aterials is presented. The technique involves the use of controlled in dentation flaws and treats time-to-failure as an experimentally fixed parameter rather than a dependent variable. Experimental advantages in clude specimen economy and unambiguous data analysis (for example, no specimens or results are lost due to test ''run-out''). The technique is applied to a borosilicate glass and the data compared with indentat ion fracture mechanics predictions from a previous study. The data sho w the significant effects of a reactive environment, in this case wate r, to reduce the failure stress of components.