The creep and fatigue tests at different frequencies are carried out to obtain creep properties and the fatigue life of the polymethyl methacrylate YB-3.Then the fatigue-damage and the creep-damage created during fatigue tests are separated.
The elastic modulus of post service and new HP Nb materials were measured according to free vibration theory of sheet bending. The radial distribution of creep damages of furnace tubes was determined in terms of elastic modulus variation.
The failure modes and influential factors of high temperature equipment and components were presented, an outline was given of the research state of high temperature creep damages and fracture theory, the control parameters of high temperature crack growth and their applications were described.
Microstructures of 12Cr1MoV/R102 dissimilar steel joints and their creep damages for the reheater after running about 80 000 hours have been analyzed and investigated. The results show that microstructure of the coarse grained region in heat affected zone(CGHAZ)deteriorate slightly compared with that of incompletely recrystallized region and base metal which deteriorate moderately.
Four typical fatigue creep cumulative damage models were briefly described, i.e., the linear cumulative damage model, the damage rate method, the ductility exhaustion model and the overstress model. The improvement and extension of these models to multiaxial fatigue creep were introduced in detail.
Examples of creep damage (Type 4) and evaluation methods
Based on the damage theory, the equations of the creep damage variant and the long-term pullout strength of anchor were derived.
Meso approaches for the creep damage behavior of nickel-base directionally solidified superalloys
A self-consistent creep damage constitutive model and a finite element model have been developed for nickel-base directionally solidified superalloys.
The numerical analysis shows that the modeled creep damage behaviors of nickel-base directionally solidified superalloys with different crystallographic orientations are in good agreement with the experimental data.