High-Temperature Low-Cycle Fatigue Experiments on Hastelloy X

Carden, A. E.; Slade, T.D.

doi:10.1520/stp33652s

Cited by 6 publications

(3 citation statements)

References 6 publications

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“…For Hastelloy X 3, out-of-phase loadings conducted at temperatures greater than 600°C were found to introduce a cyclic specimen instability referred to as barreling. This behavior has been noted in several materials under a variety of loading conditions [4][5][6][7][8][9][10][11]. Barreling is a cycle-by-cycle ratchetting phenomenon promoting material flow and localized straining; on a cylindrical specimen, this behavior is evidenced as circumferential bulging.…”

Section: Problem Areas/issuesmentioning

confidence: 91%

“…Although this behavior has been noted on several different materials during high temperature deformation, investigators have only speculated as to its cause [4][5][6][7][8][9][10][11] and how it relates to the specific test conditions. The barreling has been attributed in part to several sources including inelastic strain magnitude, strain rate, specimen geometry, and mean stress.…”

Section: Problem Areas/issuesmentioning

confidence: 99%

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Improved Techniques for Thermomechanical Testing in Support of Deformation Modeling

Castelli¹,

Ellis

1993

Thermomechanical Fatigue Behavior of Materials

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ABSTRACT:The feasibility of generating precise thermomechanical deformation data to support constitutive model development was investigated. Here, the requirement is for experimental data that is free from anomalies caused by less than ideal equipment and procedures. A series of exploratory tests conducted on Hastelloy X showed that generally accepted techniques for strain controlled tests were lacking in at least three areas. Specifically, problems were encountered with specimen stability, thermal strain compensation and temperature/mechanical strain phasing. The present study was undertaken to identify the source of these difficulties and to develop improved thermomechanical testing techniques to correct them. These goals were achieved by developing improved procedures for measuring and controlling thermal gradients and by designing a specimen specifically for thermo mechanical testing. In addition, innovative control strategies were developed to correctly proportion and phase the thermal and mechanical components of strain. Subsequently, the improved techniques were used to generate deformation data for Hastelloy X over the temperature range, 200 to 1000°C. Introduction OverviewThe majority of structural components used in high temperature applications experience some form of thermomechanical loading during service. In order to predict performance under such loadings, it is essential that precise thermomechanical tests be conducted on candidate materials. In particular, if thermomechanical testing is performed in support of constitutive model development, the data must be free of anomalies introduced by less than ideal test equipment and control techniques. To this end, recent advances in digital control systems, instrumentation, and mechanical testing equipment have eliminated many of the difficulties encountered in earlier studies. However, maintaining closely controlled conditions during thermomechanical loading remains a relatively complex task, requiring detailed examination. It is also worthy to note that to date, a standard recommended practice for conducting thermomechanical deformation and/or fatigue testing does not exist.A state-of-the-art testing facility has been established at NASA Lewis in support of high temperature deformation and fatigue testing of advanced materials. A number of exploratory tests were conducted to investigate the feasibility of generating precise

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Section: Problem Areas/issuesmentioning

confidence: 91%

Section: Problem Areas/issuesmentioning

confidence: 99%

Improved Techniques for Thermomechanical Testing in Support of Deformation Modeling

Castelli¹,

Ellis

1993

Thermomechanical Fatigue Behavior of Materials

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“…Relationships between f and fatigue life, N f , for the nickel-based superalloy Hastelloy X have been obtained at different temperatures from an extensive literature survey. [33][34][35][36][37][38][39][40][41] At a point in the structure, i.e., a node of the conjugate 3D model, rain-flow cycle counting 42 is performed for the shear stress loading history over differently oriented planes. Fatigue damage is evaluated using the calculated Findley parameter, and the compiled temperature dependent f -N f relations for each loading cycle.…”

Section: Measures Of Crack Nucleationmentioning

confidence: 99%

Towards a Coupled Loads-Response-Life Prediction Framework for Hypersonic Structures in Combined Extreme Environments

Sobotka

Oral

Culler

2013

54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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This study presents a novel computational framework to improve life prediction capabilities for hypersonic aerospace platforms where evaluating the performance of these structures in extreme environments remains a challenge. Here, thermo-mechanical loading histories determined from analyses that couple aerodynamic loads and structural deflections drive high-fidelity continuum models of the structural member, and results from the continuum model in turn drive critical-plane models of fatigue crack nucleation and growth. This approach readily enables complex features of the loading, geometry, and material response to be incorporated by the structural response and life predictions. Results shown here demonstrate the capabilities of this framework, including: representative thermomechanical and acoustic loadings from ascent to cruise conditions through to descent, the full structural response history, and damage indications that incorporate the full thermocyclic history. Preliminary studies on a challenge structural panel indicate that the ascent and descent phases of the flight profile represent the primary drivers for large residual deflections (on the order of the skin thickness), that remain present in subsequent flights and that may degrade aerodynamic and structural performance. Furthermore, the highly cyclic and transient response present in the acoustic loading phase contributes strongly to localized fatigue damage. Nomenclature b= compressibility exponent C p = pressure coefficient F c = compressible flow transformation function H = enthalpy k = parameter representing compressibility and heat transfer effects M = Mach number m = viscosity power law exponent, η/η e = (T /T e ) m n = velocity power law exponent, U/U e = (y/δ) (1/n) P r = Prandtl number p = pressurẽ p = rms fluctuating pressure q = ρU 2 /2, dynamic pressure r = P r 1/3 , turbulent flow recovery factor T = temperature U = velocity y = normal distance into boundary layer from wall γ = ratio of specific heats δ = boundary layer thickness δ 1 = boundary layer displacement thickness η = viscosity λ = viscous/velocity power law exponent ρ = density φ(ω) = power spectral density ω = frequency, rad/s Subscripts a = attached flow aw = adiabatic wall e = edge of boundary layer s = separated flow w = wall Superscripts * = reference enthalpy condition

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1969

MANN¹

1990

Bibliography on the Fatigue of Materials, Components and Structures

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High-Temperature Low-Cycle Fatigue Experiments on Hastelloy X

Cited by 6 publications

References 6 publications

Improved Techniques for Thermomechanical Testing in Support of Deformation Modeling

Improved Techniques for Thermomechanical Testing in Support of Deformation Modeling

Towards a Coupled Loads-Response-Life Prediction Framework for Hypersonic Structures in Combined Extreme Environments

1969

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