scholarly journals A Miniaturized Thin-Plate Low Cycle Fatigue Test Method at Elevated Temperature

2021 ◽  
Author(s):  
Li M. ◽  
Maskill S. ◽  
Wen Z.X. ◽  
Yue Z.F. ◽  
Sun W.
Keyword(s):  
High Temperature ◽  
Thin Plate ◽  
Reference Strain ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Test Method ◽  
Data Conversion ◽  
Creep Fatigue ◽  
Equivalent Conditions ◽  
Good Agreement

This study aims to develop a high temperature LCF test method using a non-standard miniature thin-plate (MTP) specimen in order to characterize cyclic visco-plasticity behavior of component materials. For demonstration, fully reversed strain-range controlled LCF and creep-fatigue (CF) tests at 600 °C have been performed for a martensitic steel using both standard-sized full-scale (SSFS) and MTP specimens. A scaling factor is determined using cyclic visco-plastic finite element (FE) for geometry constraint evaluation and data conversion based on the reference strain approach. The equivalent energy principal is proposed to assess the geometry constraint effect that non-standard MTP specimen has. The high temperature LCF results from the MTP specimen based on the proposed testing methodology have shown a good agreement with SSFS specimen data under equivalent conditions. The methodology can therefore be used to conduct accurate transferability to achieve equivalent LCF behavior between the conventional standard specimen and the MTP specimen.

Constitutive Modeling of Haynes 230 for High Temperature Fatigue-Creep Interactions

2014 ◽  
Author(s):  
Paul R. Barrett ◽  
Raasheduddin Ahmed ◽  
Tasnim Hassan
Keyword(s):  
High Temperature ◽  
Nuclear Power ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Model Development ◽  
Strain Range ◽  
Uniaxial Stress ◽  
Cycle Fatigue ◽  
Modeling Framework ◽  
Creep Fatigue

Non-linear stress analysis for high temperature cyclic viscoplasticity is increasingly becoming an important modeling framework for many industries. Simplified analyses are found to be insufficient in accurately predicting the life of components; such as a gas turbine engine of an airplane or the intermediate-heat exchanger of a nuclear power plant. As a result, advanced material models for simulating nonlinear responses at room to high temperature are developed and experimentally validated against a broad set of low-cycle fatigue responses; such as creep, fatigue, and their interactions under uniaxial stress states. . This study will evaluate a unified viscoplastic model based on nonlinear kinematic hardening (Chaboche type) with several added features of strain-range-dependence, rate-dependence, temperature-dependence, static recovery, and mean-stress-evolution for Haynes 230database. Simulation-based model development for isothermal creep-fatigue responses are all critically evaluated for the developed model. The robustness of the constitutive model is demonstrated and weaknesses of the model to accurately predict low-cycle fatigue responses are identified. Paper published with permission.

scholarly journals Constitutive Modeling of High Temperature Uniaxial Creep-Fatigue and Creep-Ratcheting Responses of Alloy 617

2013 ◽  
Author(s):  
P. G. Pritchard ◽  
L. Carroll ◽  
T. Hassan
Keyword(s):  
High Temperature ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Cyclic Hardening ◽  
Parameter Determination ◽  
Model Framework ◽  
Alloy 617 ◽  
North Carolina State University ◽  
Uniaxial Creep ◽  
Creep Fatigue

Inconel Alloy 617 is a high temperature creep and corrosion resistant alloy and is a leading candidate for use in Intermediate Heat Exchangers (IHX) of the Next Generation Nuclear Plants (NGNP). The IHX of the NGNP is expected to experience operating temperatures in the range of 800°–950°C, which is in the creep regime of Alloy 617. A broad set of uniaxial, low-cycle fatigue, fatigue-creep, ratcheting, and ratcheting-creep experiments are conducted in order to study the fatigue and ratcheting responses, and their interactions with the creep response at high temperatures. A unified constitutive model developed at North Carolina State University is used to simulate these experimental responses. The model is developed based on the Chaboche viscoplastic model framework. It includes cyclic hardening/softening, strain rate dependence, strain range dependence, static and dynamic recovery modeling features. For simulation of the alloy 617 responses, new techniques of model parameter determination are developed for optimized simulations. This paper compares the experimental responses and model simulations for demonstrating the strengths and shortcomings of the model.

High-Temperature Low-Cycle Fatigue Behavior of MarBN at 600 °C

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Richard A. Barrett ◽  
Eimear M. O'Hara ◽  
Padraic E. O'Donoghue ◽  
Sean B. Leen
Keyword(s):  
High Temperature ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Fatigue Behavior ◽  
Strain Range ◽  
Material Model ◽  
Cyclic Softening ◽  
Cyclic Strength ◽  
Cycle Fatigue ◽  
Viscoplastic Material

This paper presents the high-temperature low-cycle fatigue (HTLCF) behavior of a precipitate strengthened 9Cr martensitic steel, MarBN, designed to provide enhanced creep strength and precipitate stability at high temperature. The strain-controlled test program addresses the cyclic effects of strain-rate and strain-range at 600 °C, as well as tensile stress-relaxation response. A recently developed unified cyclic viscoplastic material model is implemented to characterize the complex cyclic and relaxation plasticity response, including cyclic softening and kinematic hardening effects. The measured response is compared to that of P91 steel, a current power plant material, and shows enhanced cyclic strength relative to P91.

The Residual Life Prediction of High Temperature Low Cycle Fatigue of 30CrMnSiA Steel

2014 ◽  
Vol 633-634 ◽  
pp. 184-187 ◽  
Author(s):  
Guo Dong Gao ◽  
Wen Xiao Zhang ◽  
Wang Zheng
Keyword(s):  
High Temperature ◽  
Life Prediction ◽  
Residual Life ◽  
Low Cycle Fatigue ◽  
Rbf Neural Network ◽  
Cycle Fatigue ◽  
Mechanical Fatigue ◽  
Steel Base ◽  
Network Method ◽  
Good Agreement

The analysis of the residual life of high temperature low cycle fatigue of 30CrMnSiA steel plays important roles in improving security and avoiding accidents. In this paper, the RBF neural network method is used to predict the residual life of high temperature low cycle fatigue of 30CrMnSiA steel base on data from the thermo-mechanical fatigue test. The feasibility of the method is proved by a practice example, and the learning results are in good agreement with the experimental data.

scholarly journals On Creep Fatigue Interaction of Components at Elevated Temperature

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Daniele Barbera ◽  
Haofeng Chen ◽  
Yinghua Liu
Keyword(s):  
High Temperature ◽  
Mechanical Load ◽  
Direct Method ◽  
Bending Moment ◽  
Strain Range ◽  
Cyclic Plasticity ◽  
Element Analysis ◽  
Total Strain Range ◽  
Creep Fatigue ◽  
A Direct Method

The accurate assessment of creep–fatigue interaction is an important issue for industrial components operating with large cyclic thermal and mechanical loads. An extensive review of different aspects of creep fatigue interaction is proposed in this paper. The introduction of a high temperature creep dwell within the loading cycle has relevant impact on the structural behavior. Different mechanisms can occur, including the cyclically enhanced creep, the creep enhanced plasticity and creep ratchetting due to the creep fatigue interaction. A series of crucial parameters for crack initiation assessment can be identified, such as the start of dwell stress, the creep strain, and the total strain range. A comparison between the ASME NH and R5 is proposed, and the principal differences in calculating the aforementioned parameters are outlined. The linear matching method (LMM) framework is also presented and reviewed, as a direct method capable of calculating these parameters and assessing also the steady state cycle response due to creep and cyclic plasticity interaction. Two numerical examples are presented, the first one is a cruciform weldment subjected to cyclic bending moment and uniform high temperature with different dwell times. The second numerical example considers creep fatigue response on a long fiber reinforced metal matrix composite (MMC), which is subjected to a cycling uniform thermal field and a constant transverse mechanical load. All the results demonstrate that the LMM is capable of providing accurate solutions, and also relaxing the conservatisms of the design codes. Furthermore, as a direct method, it is more efficient than standard inelastic incremental finite element analysis.

Verification of the Prediction Methods of Strain Range in Notched Specimens Made of Mod.9Cr-1Mo

2010 ◽  
Author(s):  
Masanori Ando ◽  
Yuichi Hirose ◽  
Shingo Date ◽  
Sota Watanabe ◽  
Yasuhiro Enuma ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Elevated Temperature ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Fatigue Tests ◽  
Estimation Methods ◽  
Prediction Methods ◽  
Test Machine ◽  
Notched Specimens ◽  
Creep Fatigue

Several innovative prediction methods of strain range have been developed in order to apply to the Generation IV plants. In a component design at elevated temperature, ‘strain range’ is used to calculate the fatigue and creep-fatigue damage. Therefore, prediction of ‘strain range’ is one of the most important issues to evaluate the components’ integrity during these lifetimes. To verify the strain prediction method of discontinues structures at evaluated temperature, low cycle fatigue tests were carried out with notched specimens. All the specimens were made of Mod.9Cr-1Mo, because it is a candidate material for a primary and secondary heat transports system components of JSFR (Japanese Sodium Fast Reactor). Deformation control fatigue tests and thermal fatigue tests were performed by ordinary uni-axial push-pull test machine and equipment generating the thermal gradient in the notched plate by induction heating. Stress concentration level was changed by varying the notch radius in the both kind of tests. Crack initiation and propagation process during the fatigue test were observed by the digital micro-scope and replica method. Elastic and inelastic FEAs were also carried out to estimate the ‘strain range’ for the prediction of fatigue life. Then the ranges of several strain predictions and estimations were compared with the test results. These predictions were based on the sophisticated technique to estimate the ‘strain range’ from elastic FEA. Stress reduction locus (SRL) method, simple elastic follow-up method, Neuber’s rule method and the methods supplied by elevated temperature design standards were applied. Through these results, the applicability and conservativeness of these strain prediction and estimation methods, which is the basis of the creep-fatigue life prediction, is discussed.

scholarly journals Effect of Strain Range on the Low Cycle Fatigue in Alloy 617 at High Temperature

Metals ◽  
2017 ◽  
Vol 7 (2) ◽  
pp. 54 ◽  
Author(s):  
Rando Dewa ◽  
Seon Kim ◽  
Woo Kim ◽  
Eung Kim
Keyword(s):  
High Temperature ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Cycle Fatigue ◽  
Alloy 617
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