Optimal structural design of cylindrical shells under overall bending, torsion, tension and internal pressure in creep conditions is considered. The material is assumed to be governed by the Norton-Odqvist nonlinear steady creep law. Minimal weight of the shell is the design objective, radius and wall thickness are design variables, and the constraint refers to brittle creep rupture as describe...

S U M M A R Y We use idealized subduction megathrust models to examine aseismic, frictional fault creep throughout the interseismic period. We consider rate-dependent and rateand state-dependent friction. When there is significant post-seismic creep surrounding locations of coseismic slip, the creep rates surrounding an asperity may be lower than the plate convergence rate late in the seismic c...

Alloys meeting the requirements of “700 °C and above” advanced ultra-super-critical technology, with higher thermal efficiency, have been developed in recent years. Here, a new wrought Ni-based superalloy excellent high-temperature creep strength based on Waspaloy has is proposed as candidate material for application 700 class steam turbine blades. In this alloy, Molybdenum (Mo) partially repla...

Gamma titanium aluminides (γ-TiAl) display significantly improved high temperature mechanical properties over conventional titanium alloys. Due to their low densities, these alloys are increasingly becoming strong candidates to replace nickel-base superalloys in future gas turbine aeroengine components. To determine the safe operating life of such components, a good understanding of their creep...

The present paper studies stress, temperature and heat dependence of creep rupture life 9Cr-1.8W-0.5Mo-VNb (Gr. 92) steel with data 4 heats reported in National Institute for Materials Science Creep Data Sheet 48B. In Gr. 92 there are four regions, H, M, L G, showing different stress life. increases increasing hardness after tempering Regions H M (high medium stress), prior austenite grain size...

The tensile creep and creep-recovery behavior of a unidirectional Sic-fiher/Si,N,-matrix composite was investigated at 1200°C in air. A primary objective of the study was to determine how various sustained and cyclic creep loading histories would influence the creep rate, accumulated creep strain, and the amount of strain recovered upon specimen unloading. The key results obtained from the inve...

The classic Kachanov-Rabotnov isotropic creep damage constitutive model has been used in many situations to predict the creep deformation of high temperature components. Typically, the secondary creep behavior is determined by analytical methods; however, the tertiary creep damage constants are found using a mixture of trial and error and numerical optimization. These methods require substantia...

In this study, a large number of creep tests were carried out to study the effect of stress level and testing temperature on the creep behavior of 63 Sn/37Pb solder in a systematic manner. Based on the dislocation controlled creep mechanism and Gibbs’ free-energy theory, a new creep constitutive model was proposed. The model was found to describe accurately the creep flow of the solder and to b...