No abstract

No abstract

No abstract

In locations exposed to freezing conditions over the station service life, additional measures for selecting adequate station insulators at distribution and transmission voltage levels should be taken. This second part of the paper describes the selection process and mitigation options, based on the environmental parameters, as discussed in Part I. These include insulator size, shape, surface material, surface quality, electric field improvement, and orientation.

ABSTRACT

Bismuth vanadate has been used as a model system to examine toughening by stress-induced domain motion in a ferroelastic material. Fracture toughnesses in the ferroelastic and paraelastic states have been compared. Toughening and R-curve behavior have been observed in the ferroelastic state. Single crystals of BiV04 show domain nucleation and propagation under compressive loading and domain generation during fracture. The increase in toughening in the ferroelastic state can be explained by a combination of crack deflection and domain wall motion, the latter contributing to R-curve behavior. [

Indentation‐crack‐length procedures were used to determine the critical fracture toughness (KIC) and the sensitivity to environmentally enhanced crack growth in heavy‐metal fluoride glasses of varying chemical composition. The data show that while KIC was more or less invariant with composition, some glasses were more susceptible to subcritical crack growth than others. The results are interpreted in terms of existing crack‐growth models. A technique for predicting KIC from fundamental atomic bonding and crystal‐structure data for these glasses is discussed.

No abstract