Damage Evolution and Life Prediction of a P91 Longitudinal Welded Tube Under Internal Pressure Creep

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Takashi Ogata ◽  
Takayuki Sakai ◽  
Masatsugu Yaguchi
Keyword(s):  
Internal Pressure ◽  
Void Growth ◽  
Damage Evolution ◽  
Life Prediction ◽  
Prediction Method ◽  
Creep Damage ◽  
Triaxial Stress ◽  
Creep Tests ◽  
P91 Steel ◽  
Welded Tube

The clarification of creep damage mechanism and the establishment of remaining life prediction methods of longitudinal welded piping of P91 steel are important subjects to maintain a reliable operation of boilers in thermal power plants. Internal pressure creep tests were conducted on P91 steel longitudinal welded tubes to characterize the evolution of creep damage with time and to evaluate a life prediction method. Interrupted creep tests were performed for damage observation in addition to rupture tests. Three dimensional finite element creep analyses of the longitudinal welded tube specimens were conducted to identify the stress and creep strain distributions within the specimen during creep. Failure occurred at a heat affected zone (HAZ) without a significant macroscopic deformation. It was found that the initiation of creep voids had concentrated at the midthickness region in the HAZ rather than in the surface. The creep analysis results indicated that the triaxial tensile stress yielded at the midthickness region in the HAZ due to difference of creep deformation property among the base metal, the HAZ, and the weld metal. It was suggested that the triaxial stress state caused acceleration of the creep damage evolution in the HAZ, resulting in internal failure of the tube specimens. A rupture time prediction method of the welded tube is proposed based on the maximum principal stress and the triaxial stress factor in the HAZ. The void growth behavior in the HAZ was well predicted by the previously proposed void growth simulation method by introducing a void initiation function to the method.

Damage Evolution and Life Prediction of a P91 Longitudinal Welded Tube Under Internal Pressure Creep

2008 ◽  
Author(s):  
Takashi Ogata ◽  
Takayuki Sakai ◽  
Masatsugu Yaguchi
Keyword(s):  
Internal Pressure ◽  
Heat Affected Zone ◽  
Void Growth ◽  
Damage Evolution ◽  
Life Prediction ◽  
Prediction Method ◽  
Creep Damage ◽  
Creep Tests ◽  
Creep Analysis ◽  
Welded Tube

Clarification of creep damage mechanism and establishment of remaining life prediction methods of longitudinal welded piping of P91 steel are important subjects to maintain reliable operation of boilers in thermal power plants. Internal pressure creep tests were conducted on P91 steel longitudinal welded tubes to characterize the evolution of creep damage with time and to evaluate a life prediction method. Interrupted creep tests were utilized for damage observation in addition to rupture tests. Three dimensional FE creep analysis of the creep tested specimens were conducted to identify stress and creep strain distribution within the specimen during creep. Failure occurred at a heat affected zone without significant macroscopic deformation. It was found that initiation of creep voids had concentrated at mid-thickness region rather than surface. The creep analysis results indicated that triaxial tensile stress yielded at the mid-thickness region of the heat affected zone due to difference of creep deformation property between the base metal, heat affected zone and weld metal. It was suggested that the triaxial stress state caused acceleration of the creep damage evolution in the heat affected zone resulting in internal failure of the tube specimens. A rupture time prediction method of the welded tube is proposed based on the maximum principal stress and the triaxial stress factor. Void growth behavior in the heat affected zone was well predicted by the previously proposed void growth simulation method by introducing void initiation function to the method.

Full Size Internal Pressure Creep Test for Welded P91 Hot Reheat Piping

2004 ◽  
Author(s):  
Isamu Nonaka ◽  
Takuya Ito ◽  
Fumio Takemasa ◽  
Kensuke Saito ◽  
Yoshikazu Miyachi ◽  
...  
Keyword(s):  
Internal Pressure ◽  
Damage Detection ◽  
Creep Test ◽  
Life Prediction ◽  
Prediction Method ◽  
Creep Damage ◽  
Assessment Method ◽  
Life Assessment ◽  
Full Size ◽  
Test Component

In order to establish the life assessment method for the welded modified 9Cr-1Mo steel hot reheat piping, an internal pressure creep test is conducted with a full size test component. As a result, the fracture mode of the component is clarified and the life prediction method is established. Furthermore, the creep damage detection procedures are proposed.

Full Size Internal Pressure Creep Test for Welded P91 Hot Reheat Elbow

2004 ◽  
Author(s):  
Isamu Nonaka ◽  
Takuya Ito ◽  
Fumio Takemasa ◽  
Kensuke Saitou ◽  
Yoshikazu Miyachi ◽  
...  
Keyword(s):  
Internal Pressure ◽  
Damage Detection ◽  
Creep Test ◽  
Life Prediction ◽  
Prediction Method ◽  
Creep Damage ◽  
Assessment Method ◽  
Life Assessment ◽  
Full Size ◽  
Test Component

In order to establish the life assessment method for the welded modified 9Cr-1Mo steel hot reheat elbow, an internal pressure creep test is conducted with a full size test component. As a result, the fracture mode of the component is clarified and the life prediction method is established. Furthermore, the creep damage detection procedures are proposed.

scholarly journals Viscoelastic Damage Characteristics of Asphalt Mixtures Using Fractional Rheology

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5892
Author(s):  
Qipeng Zhang ◽  
Xingyu Gu ◽  
Zilu Yu ◽  
Jia Liang ◽  
Qiao Dong
Keyword(s):  
Damage Evolution ◽  
High Stress ◽  
Creep Damage ◽  
Asphalt Mixtures ◽  
Creep Process ◽  
Model Parameters ◽  
Creep Tests ◽  
Steady Stage ◽  
Stress Levels ◽  
Different Temperatures

The mechanical behavior of asphalt mixtures at high stress levels are characterized by non-linear viscoelasticity and damage evolution. A nonlinear damage constitutive model considering the existence of creep hardening and creep damage mechanisms in the entire creep process is proposed in this study by adopting the fractional rheology theory to characterize the three-stage creep process of mixtures. A series of uniaxial compressive creep tests under various stresses were conducted at different temperatures to verify the model. The results indicated that the model predictions were in good agreement with the creep tests. The relationship between the model parameters and applied stresses was established, and the stress range in which the mixture exhibited only creep consolidation was obtained. The damage to the asphalt mixture was initiated in the steady stage; however, it developed in the tertiary stage. A two-parameter Weibull distribution function was used to describe the evolution between the damage values and damage strains at different stress levels and temperatures. The correlation coefficients were greater than 0.99 at different temperatures, indicating that a unified damage evolution model could be established. Thus, the parameters of the unified model were related to material properties and temperature, independent of the stress levels applied to the mixtures.

Thermomechanical fatigue life prediction method for nickel-based superalloy in aeroengine turbine discs under multiaxial loading

2019 ◽  
Vol 28 (9) ◽  
pp. 1344-1366 ◽  
Author(s):  
Fang-Dai Li ◽  
De-Guang Shang ◽  
Cheng-Cheng Zhang ◽  
Xiao-Dong Liu ◽  
Dao-Hang Li ◽  
...  
Keyword(s):  
Fatigue Damage ◽  
Cyclic Deformation ◽  
Deformation Behavior ◽  
Life Prediction ◽  
Prediction Method ◽  
Creep Damage ◽  
Damage Mechanism ◽  
Thermomechanical Fatigue ◽  
Nickel Based Superalloy ◽  
Creep Fatigue

The multiaxial thermomechanical fatigue properties for nickel-based superalloy GH4169 in aeroengine turbine discs are investigated in this paper. Four types of axial–torsional thermomechanical fatigue experiments were performed to identify the cyclic deformation behavior and the damage mechanism. The experimental results showed that the creep damage can be generated under thermally in-phase loading while it can be ignored under thermally out-of-phase loading, and the responded stress increasing phenomenon, that is, non-proportional hardening, can be shown under the mechanically out-of-phase strain loading. Based on the analysis of cyclic deformation behavior and damage mechanism, a life prediction method was proposed for multiaxial thermomechanical fatigue, in which the pure fatigue damage, the creep damage, and the interaction between them were simultaneously considered. The pure fatigue damage can be calculated by the isothermal fatigue parameters corresponding to the temperature without creep; the creep damage can be calculated by the principle of subdivision, and the creep–fatigue interaction can be determined by creep damage, fatigue damage, and an interaction coefficient which is used to reflect the creep–fatigue interaction strength. The predicted results showed that the proposed method is reasonable.

Investigation of Cyclic Creep Behavior and Life Prediction Method of Notch Specimen During High Temperature Fatigue

2008 ◽  
Author(s):  
Zhichao Fan ◽  
Xuedong Chen ◽  
Heng Jiang ◽  
Jie Dong
Keyword(s):  
High Temperature ◽  
Fatigue Life ◽  
Creep Behavior ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Prediction Method ◽  
Creep Damage ◽  
Cyclic Creep ◽  
High Temperature Stress ◽  
The Mean

Cyclic creeps can bring to additional damage, resulting in shorter fatigue lives, so the effects of fatigue damage and cyclic creep damage should be taken into account in the life prediction. In this case, the mean strain rate model based on ductility exhaustion theory can be adopted. An engineering structure inevitably has some stress concentration area. As to this situation, by high temperature low cycle fatigue tests with different notch sizes, cyclic creep behavior is investigated and compared with that of smooth specimens in this paper. The results indicate that, due to existence of notch, the cyclic creep deformation is restricted within a little range around notch and cannot spread widely, so the fatigue strength of notch specimens increases. Based on the ductility dissipation theory and effective stress concept of continuum damage mechanism (CDM), the mean displacement rate at half life is acted as control parameter, and a high temperature multi-axial fatigue life prediction method is proposed in this paper. The prediction results show that all test data are within ±2.0 error factor, which is better than that of axial maximum stress method. This method has simple form and fewer constants, can be used to predict high temperature stress-controlled fatigue life whatever smooth or notch specimens.

A Fatigue Life Prediction Method for Composite Lamina

2013 ◽  
Vol 787 ◽  
pp. 200-204
Author(s):  
Wen Jing Shi ◽  
Yong Bo Zhang ◽  
Wei Ping Hu
Keyword(s):  
Fatigue Life ◽  
Damage Evolution ◽  
Life Prediction ◽  
Evolution Equations ◽  
Prediction Method ◽  
Fatigue Life Prediction ◽  
Fiber Reinforced Polymer ◽  
Damage Degree ◽  
Reinforced Polymer ◽  
The Matrix

In this paper, a fatigue life prediction method for fiber reinforced polymer composite lamina is proposed. Based on two independent introduced damage variables, the damage degree of fiber and the damage degree of matrix, the issue of lamina fatigue is transformed into the study of damage evolution for fiber and matrix. Subsequently, the damage driving force and the damage evolution equations for the fiber and the matrix are constructed, respectively. Then, a novel parameter identified method is conducted. Finally, with the failure criterion for the lamina presented, the fatigue life prediction method of the composite lamina is proposed.

Study on Anisotropic Fatigue Damage Model of Metal Component

2011 ◽  
Vol 21 (4) ◽  
pp. 599-620 ◽  
Author(s):  
Zhang Miao ◽  
Meng Qingchun ◽  
Hu Weiping ◽  
Zhang Xing
Keyword(s):  
Fatigue Life ◽  
Damage Evolution ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Evolution Equations ◽  
Prediction Method ◽  
Volume Element ◽  
Fatigue Life Prediction ◽  
Repeated Loading ◽  
Damage Evolution Equation

First of all, the boom–panel model is constructed to describe the anisotropic damage evolution of continuum volume element. The constitutive relation of continuum volume element is represented by damage extent of the booms and panels. Furthermore, based on irreversible thermodynamics, damage evolution equations of boom and panel are constructed. The fatigue life prediction method for smooth specimen under the repeated loading with constant strain amplitude is constructed. By the theory of conservative integral in damage mechanics, the fatigue life prediction method for notched specimen under the repeated loading with constant amplitude is obtained. Using these methods, the material parameters of LC4CS aluminum alloy in the damage evolution equation can be obtained by the mean values of experimental fatigue curves of standard specimens with KT = 1, K T = 3, and K T = 5. The computational results are in accordance with the experiment data.

Sign in / Sign up

Export Citation Format

Share Document