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exponential creep

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Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0009218
EISBN: 978-1-62708-176-4
... Abstract This article presents typical problems encountered in the analysis of experimental creep and creep-rupture data and the possible solutions to these drawbacks. It provides information on planning the test and creep strain/time relationships. The exponential creep equation...
Series: ASM Handbook
Volume: 14B
Publisher: ASM International
Published: 01 January 2006
DOI: 10.31399/asm.hb.v14b.a0005133
EISBN: 978-1-62708-186-3
... to the experimental data is an ill-posed problem, and proper regularization techniques ( Ref 13 ) should be employed to obtain meaningful fits. A fit of the load history to a sum of exponential terms is shown in Fig. 4 . The sum of exponential terms can be differentiated to obtain the creep rate as a function...
Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0003291
EISBN: 978-1-62708-176-4
... Abstract This article presents effective stress equations that are based on the von Mises criterion, the Tresca criterion, and the Huddleston criterion. It describes the calculation of effective stresses for different cases: elastic stresses, steady-state creep stresses, stresses in a fully...
Series: ASM Handbook
Volume: 22B
Publisher: ASM International
Published: 01 November 2010
DOI: 10.31399/asm.hb.v22b.a0005506
EISBN: 978-1-62708-197-9
.... Nowick and Machlin ( Ref 28 ) and Weertman ( Ref 29 ) developed the early dislocation creep models to describe climb and glide deformation mechanisms, which gave rise to many of the commonly used exponential and hyperbolic sine formulations for creep rate. Interaction or competition between deformation...
Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0003288
EISBN: 978-1-62708-176-4
... or an exponential function of stress, in contrast to the linear stress dependence of diffusional creep. At stresses and temperatures of interest to the engineer, the following behavior proposed by Norton ( Ref 7 ) and Bailey ( Ref 8 ) is generally obeyed: (Eq 1) ε ˙ = A σ n where A and n...
Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0003287
EISBN: 978-1-62708-176-4
... mathematically by an exponential or hyperbolic sine function as indicated in the figure. Alternatively, this change in behavior may be considered a natural transition between high-temperature (power law) deformation and low-temperature flow ( Ref 1 , 2 ). Fig. 5 Steady state creep properties of pure...
Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0003290
EISBN: 978-1-62708-176-4
... versus creep rate curves directly using the elastic modulus as described previously (see Fig. 7 ). As with several other studies, it was found that the data could be superimposed by horizontal translation with good precision. This means that the curves can be parameterized using an exponential...
Series: ASM Handbook
Volume: 20
Publisher: ASM International
Published: 01 January 1997
DOI: 10.31399/asm.hb.v20.a0002472
EISBN: 978-1-62708-194-8
..., an exponential temperature dependence of minimum creep rates should be viewed as an empirical correlation. Temperature change experiments on a single specimen usually do not give the same activation energy, and because the structural state changes with temperature, a temperature change sequence effect...
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 November 1995
DOI: 10.31399/asm.hb.emde.a0003024
EISBN: 978-1-62708-200-6
..., and the effect of viscoelasticity on the test methods used. Two common ways of evaluating viscoelasticity of plastics are by means of creep experiments and dynamic mechanical experiments. Graphic or tabular analysis of test data, time-temperature superposition, and empirical correlation methods are commonly...
Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0003289
EISBN: 978-1-62708-176-4
... Abstract This article discusses the methods for assessing creep-rupture properties, particularly, nonclassical creep behavior. The determination of creep-rupture behavior under the conditions of intended service requires extrapolation and/or interpolation of raw data. The article describes...
Series: ASM Handbook
Volume: 14A
Publisher: ASM International
Published: 01 January 2005
DOI: 10.31399/asm.hb.v14a.a0004020
EISBN: 978-1-62708-185-6
..., followed by the models of constitutive behavior. It provides a discussion on creep mechanisms involving dislocation and diffusional flow, such as the Nabarro-Herring creep and the Coble creep. The equations for the several creep rates are also presented. Research on the mechanism of the superplastic flow...
Series: ASM Handbook
Volume: 14B
Publisher: ASM International
Published: 01 January 2006
DOI: 10.31399/asm.hb.v14b.a0005183
EISBN: 978-1-62708-186-3
... creep mechanisms that are useful for illustrating the strong stress dependence of dislocation and diffusional flow. ambient temperature Isothermal constitutive modeling physical models strain hardening strain-rate-sensitive flow superplastic flow CONSTITUTIVE RELATIONS for metalworking...
Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0003266
EISBN: 978-1-62708-176-4
... or an exponential function of stress ( Ref 7 ). Mechanical Testing for High-Temperature Structural Alloys Maximum-use temperatures of structural materials can depend on different design criteria, such as strength or graphitization/oxidation in steels ( Table 2 ) or creep rate and rupture strength ( Table 3...
Series: ASM Handbook
Volume: 5
Publisher: ASM International
Published: 01 January 1994
DOI: 10.31399/asm.hb.v05.a0001297
EISBN: 978-1-62708-170-2
... Abstract This article focuses on the evaluation of mechanical properties of freestanding films and films adherent to their substrates. Common methods of testing freestanding films, including uniaxial tensile testing, uniaxial creep testing, biaxial testing, and beam-bending methods...
Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0003314
EISBN: 978-1-62708-176-4
... to accomplish closed loop control of materials testing systems in performing standard materials tests and for the development of custom testing applications. It explores the advanced software tools for materials testing. The article includes a description of baseline isothermal fatigue testing, creep-fatigue...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003546
EISBN: 978-1-62708-180-1
..., during straight and level flight, aircraft jet engines have essentially constant temperatures and imposed loads, where steady-state creep (and the environment) are the primary damage mechanisms. During takeoff and landing, however, the transient demand for more power output induces load and temperature...
Series: ASM Handbook
Volume: 19
Publisher: ASM International
Published: 01 January 1996
DOI: 10.31399/asm.hb.v19.a0002391
EISBN: 978-1-62708-193-1
...” fatigue damage, including high-temperature creep and oxidation, which directly contribute to damage. These mechanisms differ, depending on the strain-temperature history. They are different from those predicted by creep tests (with no reversals) and by stress-free (or constant-stress) oxidation tests...
Series: ASM Handbook
Volume: 2A
Publisher: ASM International
Published: 30 November 2018
DOI: 10.31399/asm.hb.v02a.a0006505
EISBN: 978-1-62708-207-5
... the stress dependence of the steady-state creep rate at 18 and 600 °C (64 and 1110 °F). At high temperatures and low stresses, the rate is parabolic and a function of stress. At lower temperatures and high stresses, the rate dependence changes to an exponential law. Prasad et al. ( Ref 42 ) studied creep...
Series: ASM Handbook
Volume: 2A
Publisher: ASM International
Published: 30 November 2018
DOI: 10.31399/asm.hb.v02a.a0006487
EISBN: 978-1-62708-207-5
... and temperature, but at high stress levels, typical of hot working operations, they appear to be reasonably constant. The logarithmic relation is customarily referred to as an exponential relation, because strain rate is often considered to be the dependent variable, especially for creep. Figure 12 shows...
Series: ASM Handbook
Volume: 22B
Publisher: ASM International
Published: 01 November 2010
DOI: 10.31399/asm.hb.v22b.a0005507
EISBN: 978-1-62708-197-9
.... (a) Equilibrium angles at triple junction. (b) Rotating ball method: sintering of small, single-crystal balls to a single-crystal substrate. (c) Thermal groove method. (d) Zero-creep method. (e) Balance of grain-boundary surface tension and volume driving force The measurement of dihedral angles ( Fig. 6a...