Transient thermal fracture of piezoelectric materials structures

It is generally well understood that thermal shock conditions, which arise during sudden heating or cooling of a solid, can result in very high stresses. If the thermal transient is severe enough, sudden fracture may occur. The degree of damage and strength degradation of ceramics subjected to fluctuating thermal environments is a major limiting factor in relation to service requirements and lifetime performance. Early studies to quantify the severity of thermal shock in a plate of finite thickness attempted to draw a correlation between the magnitude of maximum tensile stress on the plate surface and the likelihood of failure. This approach assumes that there are no pre-existing surface flaws. A more sophisticated fracture analysis incorporates an edge crack in the transient stress analysis and thus the degree of severity of any given thermal shock is characterized in terms of the stress intensity factor which is a function of crack size and relevant heat transfer and thermo-elastic coefficients [1-3].