Prediction of High-Temperature Long-Term Strength for Damaged Structures

A method is proposed for analytical estimation of the high-temperature long-term strength of structures with material discontinuities, which are stress raisers. We consider the processes involving the formation of diffusion pores. Diffusion processes in metals are strongly enhanced with increasing temperature and stresses.     

A Method for the Strength Prediction of Porous Ceramics

We present a fracture model for ceramic materials, according to which ceramics is regarded as a porous inhomogeneous material with a composite structure. The role of pores as stress raisers is taken into account, and their size, geometric shape, and orientation with respect to the direction of the maximum tensile stresses are shown to be important factors. The stress on the pore surface at the places of highest stress concentration, which is equal to the ultimate strength of the ceramics bonding phase, was taken as limiting (failure) stress. Probable pore sizes and shapes have been considered in terms of filler crystal size and volume content. A fracture model and a method for the mathematical determination of the strength of ceramics have been proposed, the method taking into account the strength of the constituents, their volume content, and the shape and size of possible internal defects.