scholarly journals Closure to “Discussions of ‘Creep Tests of Rotating Disks at Elevated Temperature and Comparison With Theory’” (1955, ASME J. Appl. Mech., 22, pp. 152–154)

1955 ◽  
Vol 22 (1) ◽  
pp. 154-155
Author(s):  
A. M. Wahl ◽  
G. O. Sankey ◽  
M. J. Manjoine ◽  
E. Shoemaker
Keyword(s):  
Elevated Temperature ◽  
Rotating Disks ◽  
Creep Tests

Creep Tests of Rotating Disks at Elevated Temperature and Comparison With Theory

1954 ◽  
Vol 21 (3) ◽  
pp. 225-235
Author(s):  
A. M. Wahl ◽  
G. O. Sankey ◽  
M. J. Manjoine ◽  
E. Shoemaker
Keyword(s):  
Elevated Temperatures ◽  
Experimental Program ◽  
Test Results ◽  
Rotating Disks ◽  
Creep Tests ◽  
Shear Theory ◽  
Heat Treated ◽  
Long Time ◽  
Average Tension ◽  
Creep Deformations

Abstract A theoretical and experimental program involving methods of calculating creep in rotating disks at elevated temperatures is described. This program consisted primarily of the following: (a) Obtaining forged disks from the same ingot of 12 per cent chrome steel, all disks being forged and heat-treated in the same manner; (b) making spin tests at 1000 F on three of these disks for periods up to about 1000 hr; ( ) making long-time tension-creep tests at 1000 F on many specimens cut out circumferentially from several of the other disks at stresses approximating those of the spin tests; (d) investigating theoretical methods of calculation of creep deformation in such disks; and (e) comparison of spin-test results with those calculated theoretically using average tension-creep data. It was found that available methods of calculating rotating disks based on the Mises criterion gave creep deformations too low compared to the test values, i.e., on the unsafe side for design. Considerably better agreement between test and theoretical results is obtained if the latter is based on the maximum-shear theory. Some discussion is given of the reasons for the better agreement obtained using the latter theory; these are believed to be related in part to the anisotropy of the forged material tested. Further tests on other materials are necessary before general conclusions can be drawn; however, in the absence of test data it is suggested that a conservative course in design for such disks is to apply the maximum-shear theory.

A State Variable Interpretation of Some Rate-Dependent Inelastic Properties of Steel

1978 ◽  
Vol 100 (4) ◽  
pp. 395-401 ◽  
Author(s):  
B. Larsson ◽  
B. Stora˚kers
Keyword(s):  
Stainless Steel ◽  
Elevated Temperature ◽  
Constitutive Equation ◽  
Physical Theory ◽  
Creep Tests ◽  
Variable Theory ◽  
One Dimensional ◽  
State Variable ◽  
Rate Dependent ◽  
Stress States

Based on a state variable theory proposed by Onat some discriminating creep tests of stainless steel have been designed and carried out at elevated temperature conditions. Quantitative correlations of the results are sought with predictions from a physical theory for recovery creep proposed by Lagneborg. The findings are utilized to interpret the behavior of creeping members when subjected to a rapid increase in the rate of straining. Different approaches toward generalization of physical one-dimensional creep laws to multiaxial stress states are discussed. A tentative constitutive equation applicable to the solution of general boundary value problems is proposed.

Multi-Function Device for Creep Testing at Elevated Temperature

2014 ◽  
Vol 875-877 ◽  
pp. 462-466
Author(s):  
Andrzej Majcher ◽  
Bohdan Węglowski ◽  
Paweł Ocłoń
Keyword(s):  
Elevated Temperature ◽  
Elevated Temperatures ◽  
Creep Testing ◽  
Creep Tests ◽  
Stress Changes ◽  
Basic Parameters ◽  
Variable Stresses

Searching for quick methods to assess the material usefulness for constructing machine components working at elevated temperatures and variable stresses is accompanied with development of devices facilitating such testing. The paper presents construction of a device, that enables carrying out the standard creep tests (PN-EN ISO 204) and the dedicated tests with the programmed low-cycle loads and the different profiles for temperature and stress changes. The basic parameters of the device are described and the examples of the programmed strength testings are given.

Stress Distributions in Rotating Disks Subjected to Creep at Elevated Temperature

1957 ◽  
Vol 24 (2) ◽  
pp. 299-305
Author(s):  
A. M. Wahl
Keyword(s):  
Elevated Temperature ◽  
Creep Rate ◽  
Stress Distribution ◽  
Power Function ◽  
Constant Temperature ◽  
Creep Rupture ◽  
Flow Rule ◽  
Rotating Disks ◽  
Inside Diameter ◽  
Long Time

Abstract Assuming a creep rate proportional to a power function of the stress, curves of stress distribution as a function of the radius have been calculated for several cases of rotating disks subject to steady-state creep at elevated temperature. The disks are assumed to have central holes and to be uniformly loaded at the periphery (to simulate blade loading in turbine disks). It is also postulated that the Tresca (maximum-shear) criterion and the associated flow rule govern. The following cases are treated: (1) Disk of constant temperature and thickness with various ratios of outside to inside diameter and with various values of the exponent n in the assumed power function stress-creep rate relation. (2) Disk of constant temperature and variable thickness, the thickness at the periphery being equal to half that at the hub, for various n-values. (3) Disk with variable temperature such that the creep rate at the outside diameter is ten times that at the inside diameter for the same stress, various n-values being assumed. Limits of radial peripheral loading beyond which the derived stress-distribution curves are not valid are also determined. The results indicate that a considerable nonuniformity in stress distribution under creep conditions may exist, particularly for the lower n-values; thus creep-rupture strengths of such disks for long-time loading conditions may be lower than would be expected if based on average stress values, particularly for materials having limited ductility in long-time creep-rupture tests.

Creep Behavior of the Inconel 718 Superalloy

2012 ◽  
Vol 326-328 ◽  
pp. 509-514 ◽  
Author(s):  
Tarcila Sugahara ◽  
Karina Martinolli ◽  
Danieli A.P. Reis ◽  
Carlos de Moura Neto ◽  
Antônio Augusto Couto ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Creep Behavior ◽  
Inconel 718 ◽  
Base Alloy ◽  
High Surface ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Secondary Creep ◽  
Creep Tests ◽  
Surface Stability

A superalloy is an alloy developed for elevated temperature service, where relatively severe mechanical stressing is encountered, and where high surface stability is frequently required. High temperature deformation of Ni-base superalloys is very important since the blades and discs of aero engine turbine, because need to work at elevated temperature for an expected long period. The nickel-base alloy Inconel 718 has being investigated because it is one of the most widely used superalloys. The objective of this work was to evaluate the creep behavior of the Inconel 718 focusing on the determination of the experimental parameters related to the primary and secondary creep states. Constant load creep tests were conducted with at 650, 675 and 700°C and the range of stress was from 625 to 814 MPa to according to ASTM E139 standard. The relation between primary creep time and steady-state creep rate, obeyed the equation for both atmospherics conditions at 650, 675 and 700°C. The microstructural characterization employing the technique of scanning electron microscopy has been a valuable tool for understanding the mechanisms of creep.

Fatigue Characteristics of Nonferrous Bolts at Elevated Temperature

2014 ◽  
Vol 627 ◽  
pp. 265-268 ◽  
Author(s):  
Shinji Hashimura ◽  
Tetsuya Torii ◽  
Takefumi Otsu
Keyword(s):  
Elevated Temperature ◽  
Ambient Temperature ◽  
Fatigue Limit ◽  
Creep Deformation ◽  
Tensile Force ◽  
Fatigue Tests ◽  
Clamping Force ◽  
Creep Tests ◽  
Fatigue Characteristics ◽  
Force Reduction

In order to investigate fatigue characteristics of nonferrous bolts at elevated temperature, fatigue tests of bolted joints which were tightened with three kinds of nonferrous bolts were been conducted at 100°C atmosphere. The test bolts were made of A5056 aluminum alloy and AZ31 and AZX912 magnesium alloy. Creep tests of the bolts at 100°C atmosphere were also conducted. The results showed that the fatigue limit of A5056 bolt was the highest of all regardless of the ambient temperature. The fatigue limits of AZ31 bolt and AZX912 bolt also were a half of the fatigue limit of A5056 bolt at both ambient temperature. Bolt clamping force losses due to creep deformation were observed for all bolts during fatigue tests at elevated temperature. Hence as additional tests, the creep tests which was controlled either the tensile force or the displacements respectively were conducted. As the results it was seen that the clamping force losses for all bolts were remarkably large although the each creep deformation was different for each bolt material. Therefore the results indicates that we have to pay attention to the clamping force reduction due to creep deformation if we use the nonferrous bolt in high temperature.

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