Time-dependent creep stress redistribution analysis of thick-walled FGM spheres subjected to an internal pressure and a uniform temperature field is investigated. The material creep and mechanical properties through the radial graded direction are assumed to obey the simple power-law variation throughout the thickness. Total strains are assumed to be the sum of elastic, thermal and creep strain...

This paper addresses the coefficient of kinetic friction of relatively warm ice (-50 °C) sliding slowly (<1 m s) over itself and presents physical models to account for two characteristics: velocity-strengthening at lower speeds and velocity-weakening at higher speeds. The models are based upon a combination of creep deformation within a near-surface zone and frictional heating cum localized me...

Background—The creep-fatigue properties of stainless steel 316 are of interest because of the wide use of this material in demanding service environments, such as the nuclear industry. Need—A number of models exist to describe creep-fatigue behaviours, but they are limited by the need to obtain specialized coefficients from a large number of experiments, which are time-consuming and expensive. ...

The compass depressors (CDs) of the sea-urchin lantern are ligaments consisting mainly of discontinuous collagen fibrils associated with a small population of myocytes. They are mutable collagenous structures, which can change their mechanical properties rapidly and reversibly under nervous control. The aims of this investigation were to characterise the baseline (i.e. unmanipulated) static mec...

The influence of anisotropic diffusion coefficients on diffusion-controlled high-temperature creep is examined. Anisotropic diffusion affects anisotropy of diffusion-controlled deformation of a single crystal. The shape change of a single crystal by diffusional mass flux is controlled directly by the anisotropy in diffusion coefficients. The rate of shape change of a single crystal by diffusion...

Abstract Wind turbines (WT) must be further optimized concerning availability and reliability. One of the major reasons WT downtime is failure gearbox bearings. Some these failures occur, due to ring creep phenomenon, which mostly detected in planetary The phenomenon describes a relative movement outer gear. In order improve understanding creep, finite element method (FEM) used simulate gears. ...

SUMMARY c The concept that creep response is the result of a transient approach to a minimum strain rate continuously modified by accumulating damage has been investigated using high precision creep data. It was considered that the accumulated creep strain might be some measure of internal damage and curves of log creep strain rate against creep strain are shown to exhibit linearity at higher s...

In the Present study, attempt will be made to propose a new method for prediction of long-term essential creep of concrete utilizing some short-term creep tests under high temperature. To do so, regarding the similarities between essential creep of concrete and creep in viscoelastic materials, the time–temperature equivalence relation in viscoelastic materials is evaluated for concrete. This re...

Macroscopic slip velocity, macroscopic temperature jump, thermal creep velocity and diffusion slip velocity for a mixture of monatomic gases are calculated by using a method developed recently (modified Maxwell-method) for a general gas-gas and gas-surface interaction law, and for a possibly anisotropic surface. The results are expressed in terms of accommodation coefficients of first and secon...

*Lawrence J. Hagen, USDA-ARS, Wind Erosion Research Unit, Throckmorton Hall 2004, Kansas State University, Manhattan, KS 66506. *Corresponding author: [email protected]. Contribution from USDA-ARS in cooperation with Kansas Agric. Exp. Sta., Contribution No. 99-389-A. ABSTRACT Assessment of wind erosion parameters applicable to the field scale using wind tunnels requires attention to both scal...