A Study of the Effects of Cyclic Thermal Stresses on a Ductile Metal

Coffin, L. F.

doi:10.1115/1.4015020

Cited by 1,015 publications

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“…Most models are based on a physical dimension, like a certain stress or strain state, or an absorbed energy equivalent, 37 or on mathematical models, which introduce lifetime influencing parameters. A common lifetime approach is the strain-based Manson-Coffin/Basquin approach (Equation 1), which consists of the Basquin 38 and Manson-Coffin [39][40][41] equations.…”

Section: Multiaxial Fatigue Lifetime Descriptionsmentioning

confidence: 99%

“…Most models are based on a physical dimension, like a certain stress or strain state, or an absorbed energy equivalent, 37 or on mathematical models, which introduce lifetime influencing parameters. A common lifetime approach is the strain‐based Manson‐Coffin/Basquin approach (Equation 1), which consists of the Basquin 38 and Manson‐Coffin 39–41 equations.

ϵ_{a} goodbreak= ϵ_{a, italicel} goodbreak+ ϵ_{a, italicpl} goodbreak= \frac{σ_{f}^{'}}{E} {(2 N_{f})}^{b} goodbreak+ ϵ_{f}^{'} {(2 N_{f})}^{c}

This approach includes the total strain amplitude

ϵ_{a}

, the elastic strain amplitude

ϵ_{a, italicel}

, the plastic strain amplitude

ϵ_{a, italicpl}

, the total number of cycles to failure

N_{f}

, and Young's modulus

E

.…”

Section: Multiaxial Fatigue Lifetime Descriptionsmentioning

confidence: 99%

See 1 more Smart Citation

Planar‐biaxial low‐cycle fatigue behavior of the nickel‐base alloy Inconel 718 at elevated temperatures under selected loading conditions

Böcker

Babu

Henkel

et al. 2022

Fatigue Fract Eng Mat Struct

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The isothermal planar‐biaxial fatigue behavior was studied for two different disk batches of nickel‐base superalloy Inconel 718 using cruciform specimens at 400°C and 630°C under equi‐biaxial and shear loading. Additionally, non‐proportional tests were performed. The planar‐biaxial test results were compared with uniaxial reference tests using the von Mises equivalent strain hypothesis, a shear strain parameter of the critical plane, and a modified crack‐opening‐displacement strain range approach. Additionally, the crack initiation mechanism was analyzed. Using a modified crack‐opening‐displacement strain range approach, the low‐cycle fatigue lifetimes of the proportional planar‐biaxial tests (i.e., lifetimes up to 40,000 cycles) were described within a scatter band of two. Thus, it was better than using the equivalent strain of von Mises or a shear strain parameter. The fatigue crack initiation took place at oxidized primary carbides at the surface. The crack paths were presented.

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Section: Multiaxial Fatigue Lifetime Descriptionsmentioning

confidence: 99%

“…Most models are based on a physical dimension, like a certain stress or strain state, or an absorbed energy equivalent, 37 or on mathematical models, which introduce lifetime influencing parameters. A common lifetime approach is the strain‐based Manson‐Coffin/Basquin approach (Equation 1), which consists of the Basquin 38 and Manson‐Coffin 39–41 equations.

ϵ_{a} goodbreak= ϵ_{a, italicel} goodbreak+ ϵ_{a, italicpl} goodbreak= \frac{σ_{f}^{'}}{E} {(2 N_{f})}^{b} goodbreak+ ϵ_{f}^{'} {(2 N_{f})}^{c}

This approach includes the total strain amplitude

ϵ_{a}

, the elastic strain amplitude

ϵ_{a, italicel}

, the plastic strain amplitude

ϵ_{a, italicpl}

, the total number of cycles to failure

N_{f}

, and Young's modulus

E

.…”

Section: Multiaxial Fatigue Lifetime Descriptionsmentioning

confidence: 99%

Planar‐biaxial low‐cycle fatigue behavior of the nickel‐base alloy Inconel 718 at elevated temperatures under selected loading conditions

Böcker

Babu

Henkel

et al. 2022

Fatigue Fract Eng Mat Struct

View full text Add to dashboard Cite

show abstract

“…Among them, the SWT model is proposed by Smith et al, 53 and the SWT parameter extended by Socie 54 has been widely used, which is found to be suitable for aluminum alloys 55 . The expression of life model is shown below:

σ_{\max} \frac{normalΔ ε_{n}}{2} goodbreak= \frac{{σ^{'}}_{f}^{2}}{E} {(2 N_{f})}^{2 b} goodbreak+ σ_{f}^{'} ε_{f}^{'} {(2 N_{f})}^{b + c},

where

σ_{\max}

is the maximum normal stress on the critical plane,

\frac{normalΔ ε_{n}}{2}

is the positive strain amplitude on the critical plane, E is the modulus of elasticity, and

σ_{f}^{'}

ε_{f}^{'}

, b , and c are material parameters in Coffin–Manson equation, 56,57 which are calculated by using the estimation formulas 58 . And the four calculated parameters are 910 MPa, −0.095, −0.69, and 0.35, respectively.…”

Section: Two Examples Based On the Clipping Methodsmentioning

confidence: 99%

A double‐clipping method to achieve the fatigue damage equivalence between uniaxial and triaxial random vibrations

Bai

Qiu

et al. 2022

Fatigue Fract Eng Mat Struct

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In this paper, a double-clipping method dealing with both load spectrum and test time is proposed for fatigue damage equivalence between uniaxial and triaxial random vibrations. The load spectrum is clipped appropriately to avoid strength failure because of triaxial over-testing by defining the stress margin.The test time is clipped and three criteria for selecting the key equivalent points are presented to achieve fatigue damage equivalence of important components between uniaxial and triaxial random vibrations. The proposed method is verified through a notched specimen and a printed circuit board (PCB), respectively, showing that the double-clipping method not only avoids over-testing and saves test time but also provides a valuable reference for formulating triaxial random vibration test standards.

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“…The Coffin-Manson equation used in the strength calculations defines the dependence of durability under loading with controlled strain (e k = constant) on the cyclic plastic strain e 0 [35,36]:…”

Section: Statistical Assessment Of Low-cycle Fatigue Curvesmentioning

confidence: 99%

Probability Assessment of the Mechanical and Low-Cycle Properties of Structural Steels and Aluminium

Bazaras

Lukoševičius

Vilkauskas

et al. 2021

Metals

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Key mechanical properties used in low-cycle strength and durability calculations are the strength (proportional limit stress, σpr; relative yield strength, σ0.2; and ultimate tensile stress, σu) and strain properties (proportional limit strain, epr; percent area reduction, ψ; and percent area reduction at failure, ψu). When selecting the key mechanical properties provided in the specifications, an error may be made due to the failure to account for a series of random factors that determine the distribution of properties. The majority of research papers dealing with statistical descriptions of the low-cycle strain properties do not look deeper into the distribution of mechanical properties and the diagram parameters of strain characteristics. This paper provides a description of the distribution patterns of mechanical properties, statistical parameters, and low-cycle fatigue curves. Log-normal distribution generated the lowest values for the coefficient of variation of one of the key statistical indicators, suggesting that log-normal distribution is superior to normal or Weibull distribution in this respect. The distribution of low-cycle strain parameters exceeded the distribution of mechanical properties considerably. Minimum coefficients of variation of the parameters were generated at normal distribution. The statistical analysis showed the lower distribution of the durability parameters compared to the distribution of parameters of the strain diagrams. The findings of the paper enable a revision of the durability and life of the structural elements of in-service facilities subject to elastoplastic loading by assessing the distribution of mechanical characteristics and low-cycle strain parameters as well as the permissible distribution limits.

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A Study of the Effects of Cyclic Thermal Stresses on a Ductile Metal

Cited by 1,015 publications

References 0 publications

Planar‐biaxial low‐cycle fatigue behavior of the nickel‐base alloy Inconel 718 at elevated temperatures under selected loading conditions

Planar‐biaxial low‐cycle fatigue behavior of the nickel‐base alloy Inconel 718 at elevated temperatures under selected loading conditions

A double‐clipping method to achieve the fatigue damage equivalence between uniaxial and triaxial random vibrations

Probability Assessment of the Mechanical and Low-Cycle Properties of Structural Steels and Aluminium

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