Unified viscoplastic constitutive model under axial-torsional thermo-mechanical cyclic loading

Fatigue Fract Eng Mat Struct

et al. 2020

To realize online multiaxial fatigue damage assessment for the mechanical components in service, an online multiaxial cycle counting method is proposed coupled with the segment processing technique and Wang-Brow's relative equivalent strain concept. Meanwhile, considering all the stress and strain components, which contribute to the fatigue damage on the critical plane, a multiaxial fatigue damage model without any weight coefficients is also proposed in an equivalent form of shear strain energy. Then, an online fatigue damage evaluation method for multiaxial random loading is developed by combining with the proposed damage model and online cycle counting method. The experimental results showed that the proposed online cycle counting method can be successfully applied to the calculation of multiaxial fatigue damage under random loading. Moreover, the proposed online multiaxial fatigue damage evaluation method can provide satisfactory predictions. K E Y W O R D Slife prediction, multiaxial fatigue, random loading, real-time cycle counting

Section: Discussionmentioning

confidence: 99%

Online multiaxial fatigue damage evaluation method by real‐time cycle counting and energy‐based critical plane criterion

Xue

Fatigue Fract Eng Mat Struct

et al. 2020

“…In this investigation, uniaxial TMF tests, AT-TMF tests, and isothermal axial-torsional low-cycle fatigue (AT-LCF) tests were carried out on the Ni-based superalloy GH4169, and the experimental details are described in Li et al (2018Li et al ( , 2019 and Shang et al (2007). For the uniaxial TMF tests, the thermal phase angle (between the axial mechanical strain and the temperature) needs to be controlled.…”

Section: Methodsmentioning

confidence: 99%

“…The oxidation occurred when the material is exposed to elevated temperature, and the oxidation damage is dependent on temperature, time, and stress (Vo¨se et al, 2013). In addition, the fatigue, oxidation, and creep damages can be increased by the non-proportional additional hardening due to mechanical out-of-phase loading (Li et al, 2019). The influence of above damage behavior on the failure life should be considered in the damage model under AT-TMF loading.…”

Section: Introductionmentioning

confidence: 99%

Fatigue–oxidation–creep damage model under axial-torsional thermo-mechanical loading

International Journal of Damage Mechanics

Cui

et al. 2019

Self Cite

A fatigue–oxidation–creep damage model that can take into account the effect of multiaxial cyclic feature on the damage mechanism is proposed under axial-torsional thermo-mechanical fatigue loading. In the proposed model, the effects of non-proportional additional hardening on fatigue, oxidation, and creep damages are considered, and the variation of oxidation damage under different high temperature loading conditions is also described. Moreover, the intergranular creep damage needs to be equivalent to the transgranular damage before accumulating with the fatigue and oxidation damages. The fatigue, oxidation, and creep damages can be expressed as the fractions of fatigue life, critical crack length, and creep rupture time, respectively, which allows the linear accumulation of different types of damages on the basis of life fraction rule. In addition, the proposed model is validated by various fatigue experimental results, including uniaxial thermo-mechanical fatigue, axial-torsional thermo-mechanical fatigue, and isothermal axial-torsional fatigue under proportional and non-proportional loadings. The results showed that the errors are within a factor of 2.

“…In our previous investigation, 37 in order to take the nonproportional additional hardening effect into account, the back stress deviator rate

{\dot{bold-italicχ}}_{i}^{'}

can be calculated by

{\dot{bold-italicχ}}_{i}^{'} goodbreak= C_{i} ([], \frac{2}{3} ((), 1 goodbreak+ italicΦF) a_{i} {\dot{bold-italicε}}_{in} goodbreak- χ_{i}^{'} \overset{p}{true}),

where

F

is the rotation factor and

Φ

is the nonproportional hardening coefficient. As shown in Figure 3, the introduced term

((), 1 + italicΦF)

reasonably expands the asymptotic value

a

of the equivalent stress of back stress deviator under nonproportional loading.…”

Section: Viscoplastic Constitutive Modelmentioning

confidence: 99%

Viscoplastic constitutive model considering strain rate sensitivity under multiaxial thermomechanical fatigue loading

Fatigue Fract Eng Mat Struct

Chen³

et al. 2023