Steady-State Creep Analysis of Thick-Walled Spherical Pressure Vessels With Varying Creep Properties

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
L. H. You ◽  
H. Ou
Keyword(s):  
Steady State ◽  
Iterative Method ◽  
Internal Pressure ◽  
Strain Rate ◽  
Equivalent Strain ◽  
Pressure Vessels ◽  
Steady State Creep ◽  
Creep Properties ◽  
Equivalent Strain Rate ◽  
Basic Equations

Based on basic equations of steady-state creep of spherically symmetric problems, a simple and efficient iterative method is proposed in this paper to determine creep deformations and stresses in thick-walled spherical vessels with varying creep properties subjected to internal pressure. The convergence of the proposed iterative method and the influences of varying and constant material properties on stresses and equivalent strain rate are discussed. How different material parameters involved in Norton’s law affect radial and circumferential stresses together with the equivalent strain rate in thick-walled spherical vessels under internal pressure is investigated.

Steady-State Creep Deformations and Stresses in FGM Rotating Thick Cylindrical Pressure Vessels

2014 ◽  
Vol 31 (1) ◽  
pp. 1-6 ◽  
Author(s):  
M. Z. Nejad ◽  
Z. Hoseini ◽  
A. Niknejad ◽  
M. Ghannad
Keyword(s):  
Steady State ◽  
Strain Rate ◽  
Equivalent Strain ◽  
Pressure Vessels ◽  
Functionally Graded ◽  
Steady State Creep ◽  
Graded Materials ◽  
Equivalent Strain Rate ◽  
Closed Form Analytical Solution ◽  
Creep Deformations

AbstractIn the present study, a closed-form analytical solution for the steady-state creep stresses of rotating thick cylindrical pressure vessels made of functionally graded materials (FGMs) is carried out. Norton's law governs the creep response of the material. Exact solutions for stresses and strain rate are obtained under the plane strain condition. How different material parameters involved in Norton's law affect radial and circumferential stresses together with the equivalent strain rate in rotating thick-walled cylindrical vessels under internal pressure is investigated. The result obtained shows that the property of FGMs has a significant influence on the equivalent creep strain rate and stresses distributions along the radial direction.

scholarly journals Verification of Equation for Evaluating Dislocation Density during Steady-state Creep of Metals

2017 ◽  
Vol 6 (2) ◽  
pp. 20 ◽  
Author(s):  
Manabu Tamura
Keyword(s):  
Free Energy ◽  
Steady State ◽  
Dislocation Density ◽  
Shear Modulus ◽  
Strain Rate ◽  
Gibbs Free Energy ◽  
Steady State Creep ◽  
Austenitic Steels ◽  
Exponential Factor ◽  
Delta G

Ninety-two sets of observed dislocation densities for crept specimens of 21 types of ferritic/martensitic and austenitic steels, Al, W, Mo, and Mg alloys, Cu, and Ti including germanium single crystals were collected to verify an equation for evaluating the dislocation density during steady-state creep proposed by Tamura and Abe (2015). The activation energy, Qex, activation volume, Vex, and Larson–Miller constant, Cex, were calculated from the creep data. Using these parameter constants, the strain rate, and the temperature dependence of the shear modulus, a correction term, Gamma, was back-calculated from the observed dislocation density for each material. Gamma is defined in the present paper as a function of the temperature dependences of both the shear modulus and pre-exponential factor of the strain rate. The values of Gamma range from −394 to 233  and average 2.1 KJmol-1, which is a value considerably lower than the average value of Qex (410.4 KJmol-1), and values of Gamma are mainly within the range from 0 to 50 KJmol-1. The change in Gibbs free energy, Delta G, for creep deformation is obtained using the calculated value of , and the empirical relation Delta G~Delta GD is found, where Delta GD is the change in Gibbs free energy for self-diffusion of the main componential element of each material. Experimental data confirm the validity of the evaluation equation for the dislocation density.

The effect of thickness on the steady-state creep properties of freestanding aluminum nano-films

2012 ◽  
Vol 60 (11) ◽  
pp. 4438-4447 ◽  
Author(s):  
Hiroyuki Hirakata ◽  
Naomichi Fukuhara ◽  
Shoichi Ajioka ◽  
Akio Yonezu ◽  
Masayuki Sakihara ◽  
...  
Keyword(s):  
Steady State ◽  
Steady State Creep ◽  
Creep Properties

Improved tensile creep properties of yttrium- and lanthanum-doped alumina: a solid solution effect

2001 ◽  
Vol 16 (2) ◽  
pp. 425-429 ◽  
Author(s):  
Junghyun Cho ◽  
Chong Min Wang ◽  
Helen M. Chan ◽  
J. M. Rickman ◽  
Martin P. Harmer
Keyword(s):  
Solid Solution ◽  
Steady State ◽  
Creep Behavior ◽  
Solubility Limit ◽  
Steady State Creep ◽  
Tensile Creep ◽  
Creep Properties ◽  
Uniform Microstructure ◽  
Equiaxed Grains ◽  
Rare Earth Doped

The tensile creep behavior of yttrium- and lanthanum-doped alumina (at dopant levels below the solubility limit) was examined. Both compositions (100 ppm yttrium, 100 ppm lanthanum) exhibited a uniform microstructure consisting of fine, equiaxed grains. The creep resistance of both doped aluminas was enhanced, compared with undoped alumina, by about two orders of magnitude, which was almost the same degree of improvement as for materials with higher dopant levels (in excess of the solubility limit). In addition, measured creep rupture curves exhibited predominantly steady-state creep behavior. Our results, therefore, verified that the creep improvement in these rare-earth doped aluminas was primarily a solid-solution effect.

scholarly journals An An Analysis of Strain Rate Distribution Using Streamline Model and A Quick Stop Device in Metal Cutting

2019 ◽  
Vol 22 (2) ◽  
pp. 136-142
Author(s):  
Osama Ali Kadhim ◽  
Fathi A. Alshamma
Keyword(s):  
Strain Rate ◽  
Chip Formation ◽  
Metal Cutting ◽  
Equivalent Strain ◽  
Element Analysis ◽  
Rate Distribution ◽  
Equivalent Strain Rate ◽  
Cumulative Plastic Strain ◽  
Cutting Speeds ◽  
Strain Rate Distribution

In this paper, a quick stop device technique and the streamline model were employed to study the chip formation in metal cutting. The behavior of chip deformation at the primary shear zone was described by this model. Orthogonal test of turning process over a workpiece of the 6061-T6 aluminum alloy at different cutting speeds was carried out. The results of the equivalent strain rate and cumulative plastic strain were used to describe the complexity of chip formation. Finite element analysis by ABAQUS/explicit package was also employed to verify the streamline model. Some behavior of formation and strain rate distribution differs from the experimental results, but the overall trend and maximum results are approximately close. In addition, the quick stop device technique is described in detail. Which could be used in other kinds of studies, such as the metallurgical observation.

scholarly journals Creep Investigation on Shale-Like Material with Preexisting Fissure under Coupling Temperatures and Confining Pressures

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Yongyan Wang ◽  
Hongwei Wang ◽  
Xiao Shi
Keyword(s):  
Steady State ◽  
Creep Rate ◽  
Strain Rate ◽  
Confining Pressure ◽  
Steady State Creep ◽  
Steady State Creep Rate ◽  
Creep Experiment ◽  
Uniaxial Creep ◽  
Confining Pressures ◽  
Triaxial Creep

In order to investigate the influence of temperature, confining pressure, and preexisting fissure on creep characteristics of rock mass, multistage creep experiments were performed on shale-like material, with preexisting fissure under different temperatures and confining pressures. The results showed that new microcracks generated and propagated with the increase of temperature in both uniaxial and triaxial creep experiments, and the generation and propagation were most pronounced at 60°C and least at 20∼50°C in uniaxial creep experiments. The generation and propagation were restricted by confining pressure. Temperature had less influence on the creep strain rate in triaxial creep experiment, whereas it had a significant influence on the steady-state creep rate in uniaxial creep experiment. The influence of confining pressure on the steady-state creep rate was slight when confining pressure was 1 MPa, whereas it was obvious when confining pressure was 3∼7 MPa. The closure of preexisting fissure promoted the creep strain rate, and the closure was incomplete when confining pressure was below 3 MPa, whereas it was complete when confining pressure at 5 and 7 MPa.

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