Modeling the Creep Damage of P91 Steel Using Peridynamics

2019 ◽  
Author(s):  
Shank S. Kulkarni ◽  
Alireza Tabarraei ◽  
Xiaonan Wang
Keyword(s):  
Experimental Data ◽  
High Temperature ◽  
Structural Integrity ◽  
Creep Damage ◽  
Creep Model ◽  
Creep Tests ◽  
P91 Steel ◽  
Damage Models ◽  
Modeling Creep ◽  
Non Local

Abstract Creep is an important failure mechanism of metal components working at a high temperature. To ensure the structural integrity and safety of systems working at high temperature it is essential to predict failure due to creep. Classical continuum based damage models are used widely for modeling creep damage. A more recently developed non-local mechanics formulation called peridynamics has displayed better performance in modeling damage with respect to classical local mechanics methods. In this paper, the peridynamic formulation is extended to model creep in metals. We have chosen Liu-Murakami creep model for developing a peridynamic formulation for modeling creep. The proposed formulation is validated by simulating creep tests for P91 steel and comparing the results with experimental data from the literature.

On the Determination of Material Creep Constants Using Miniature Creep Test Specimens

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Tom H. Hyde ◽  
Balhassn S. M. Ali ◽  
Wei Sun
Keyword(s):  
Creep Test ◽  
Test Specimen ◽  
Creep Damage ◽  
Creep Model ◽  
P91 Steel ◽  
Notched Specimen ◽  
Material Constants ◽  
Damage Models ◽  
Uniaxial Creep ◽  
Material Creep

Full size creep test specimens, i.e., conventional uniaxial creep test specimen and Bridgman notch specimens are usually used to determine the full set of material constants for any creep model. However, in many situations, sufficient material is not available for theses specimens to be manufactured from it. Therefore, small creep test specimens have been introduced and used to determine (i) creep constants and (ii) the remaining life time for engineering components. Two commonly used small creep specimen types, i.e., the impression and the small ring creep tests, are used in this paper to determine the steady state creep constants. However, these specimen types are limited for use in determining the secondary creep properties, i.e., they are unable to determine the full set of material creep constants for creep damage models. In this paper the recently developed small two-bar creep test specimen and the newly developed small notched specimen test are described and used to determine a full set of material constants for Kachanov and Liu-Murakami creep damage models. The small notched specimen manufacturing, loading and testing procedures are described in this paper. P91 steel at 600 °C and (Bar-257) P91 steel at 650 °C have been used to compare the material constants obtained from the small two-bar and the small notched creep test specimens with those obtained from the conventional uniaxial creep test specimens and Bridgman notch specimens. The results show remarkably good agreement between the two sets of results.

scholarly journals Creep damage behavior of red sandstone after high temperature

2021 ◽  
Author(s):  
Xiaokang Pan ◽  
Filippo Berto ◽  
Xiaoping Zhou
Keyword(s):  
High Temperature ◽  
Uniaxial Compression ◽  
Deformation Modulus ◽  
Creep Damage ◽  
Viscosity Coefficient ◽  
Creep Tests ◽  
Red Sandstone ◽  
Instantaneous Strain ◽  
Treated Sample ◽  
Instantaneous Deformation

This work discusses the results from tests conducted to investigate the uniaxial compression and creep behavior of red sandstone. The original untreated sample and the 800 ℃ treated sample have been selected to carry out the experiments. It has been found that high temperature has obvious influence on the mechanical properties of red sandstone. The relationship between creep strain and instantaneous strain, as well as instantaneous deformation modulus and creep viscosity coefficient have been analyzed. It has been found that high temperature reduces the ability of red sandstone to resist instantaneous deformation and creep deformation. Acoustic emission (AE) technology has been also used in the loading process of uniaxial compression and creep tests, providing a powerful means for damage evolution analysis of red sandstone.

scholarly journals Experimental and Theoretical Studies on the Creep Behavior of Bayer Red Mud

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Baoyun Zhao ◽  
Wei Huang ◽  
Zhile Shu ◽  
Mengmeng Han ◽  
Yanbo Feng
Keyword(s):  
Creep Strain ◽  
Creep Behavior ◽  
Red Mud ◽  
Damage Model ◽  
Creep Damage ◽  
Creep Model ◽  
Creep Tests ◽  
Accelerated Creep ◽  
Bayer Red Mud ◽  
Creep Damage Model

Long-term stability and safety of the Bayer red mud (BRM) disposal field is very important for the local residents’ life, which necessitates the knowledge of its creep behavior. In order to investigate the creep behavior of BRM, a series of triaxial drained creep tests were conducted by using an improved triaxial creep apparatus. The results indicate that the creep behavior of BRM is significant with confining and deviatoric stresses being critical factors. The creep strain is in a nonlinear relationship with stress and time, and a larger deviator stress will lead to a larger creep strain. The main failure mechanism of BRM is plastic shear, accompanied by a significant compression and ductile dilatancy. Based on the test results, two well-established creep models, the Burgers creep model and Singh–Mitchell creep model, were used to comparatively analyze the creep behavior of the Bayer red mud under a certain stress level. Then, an improved Burgers creep damage constitutive model with the addition of a damage variable was proposed, whose parameters were also analyzed in detail. The comparison of the calculated values of the creep model and the experimental values shows that the proposed creep damage model can better describe the instant elastic deformation, attenuation creep, steady-state creep, and accelerated creep stages of the Bayer red mud.

scholarly journals High-Temperature Tensile and Creep Behavior in a CrMoV Steel and Weld Metal

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 109
Author(s):  
Yan Song ◽  
Mengyu Chai ◽  
Zelin Han ◽  
Pan Liu
Keyword(s):  
High Temperature ◽  
Weld Metal ◽  
Creep Damage ◽  
Uniaxial Tensile ◽  
Second Phase ◽  
Creep Tests ◽  
Damage Mechanisms ◽  
Integrity Assessment ◽  
Steel Weldment ◽  
High Temperature Tensile

The 2.25Cr1Mo0.25V steel is a vanadium-modified 2.25Cr1Mo steel and is being widely used in the manufacture of heavy-wall hydrogenation reactors in petrochemical plants. However, the harsh service environment requires a thorough understanding of high-temperature tensile and creep behaviors of 2.25Cr1Mo0.25V steel and its weld for ensuring the safety and reliability of hydrogenation reactors. In this work, the high-temperature tensile and creep behaviors of base metal (BM) and weld metal (WM) in a 2.25Cr1Mo0.25V steel weldment used for a hydrogenation reactor were studied experimentally, paying special attention to its service temperature range of 350–500 °C. The uniaxial tensile tests under different temperatures show that the WM has higher strength and lower ductility than those of BM, due to the finer grain size in the WM. At the same time, the short-term creep tests at 550 °C reveal that the WM has a higher creep resistance than that of BM. Moreover, the creep damage mechanisms were clarified by observing the fracture surface and microstructures of crept specimens with the aid of scanning electron microscopy (SEM). The results showed that the creep damage mechanisms of both BM and WM are the initiation and growth of creep cavities at the second phase particles. Results from this work indicate that the mismatch in the high-temperature tensile strength, ductility, and creep deformation rate in 2.25Cr1Mo0.25V steel weldment needs to be considered for the design and integrity assessment of hydrogenation reactors.

Prediction of Creep Life on Notched Bar Specimens of Grade 92 Steel

2016 ◽  
Author(s):  
Haruhisa Shigeyama ◽  
Yukio Takahashi ◽  
Jonathan Parker
Keyword(s):  
Finite Element ◽  
Creep Damage ◽  
Creep Data ◽  
Creep Failure ◽  
Creep Tests ◽  
Energy Fraction ◽  
Damage Models ◽  
Finite Element Software ◽  
Notched Specimens ◽  
Life Fraction

Creep tests on two kinds of circumferentially notched round bar specimens as well as plain bar specimen were performed to obtain the multiaxial and uniaxial creep data. Creep damage models of strain fraction and energy fraction rule were developed using these creep data. Then creep damage analyses using a finite element software, MSC Marc, were carried out on notched specimens of both types and creep failure lives were predicted using the creep damage models of classical life fraction rule and developed strain or energy fraction rule. Experimental failure lives of all the conditions of notched specimens were compared with analytical results. As a result, creep failure lives obtained by life fraction rule were underestimated in the short term region and overestimated in the long term region. On the other hands, it is apparent that the majority of creep failure lives obtained by strain and energy fraction rule were predicted with an accuracy within a factor of two. Furthermore, some interrupted creep tests and creep void observations were conducted on the notched specimens of both types. The distributions of creep void number density were in good agreement with the distributions of creep damage calculated by finite element analyses.

Further Development of Modified Theta Project Creep Models With Life Fraction Hardening

2017 ◽  
Author(s):  
W. David Day ◽  
Ali P. Gordon
Keyword(s):  
Structural Integrity ◽  
Turbine Blades ◽  
Material Behavior ◽  
Creep Model ◽  
Effect Of Temperature ◽  
Rotor Steel ◽  
State Variables ◽  
Creep Tests ◽  
Hardening Rule ◽  
Life Fraction

In order to optimally design a hot section component for creep, the designer and turbine durability specialist must have confidence in their predictive tools and be able to gain design insight from these analytical tools. The modified theta projection (MTP) creep model was previously presented as an accurate means of describing creep behavior as a function of stress, temperature and time. The MTP was then implemented in an analytical model using a life fraction hardening (LFH) rule to calculate creep in the presence of time-varying stresses, and the results presented in a second paper. This paper presents improvements to the technique through the use of state variables in addition to the previously shown strain life fraction (ELF) and temperature margin (TMar). The need for performing multiple creep analyses is avoided by adding state variables to that track estimates of the effect of temperature changes on stress relaxation and life fraction, as well as an allowance for material variability and an inexact fit of material behavior. The results of creep tests, on a nickel blade alloy, with incrementally increasing or decreasing loads are presented to provide validation of the accuracy of the life fraction hardening rule. The use of MTP and LFH has now been expanded to steels. Incremental testing results are examined for a NiCrMoV rotor steel to further validate the technique. The effect of true stress on model accuracy is also presented. Now that an accurate creep model and hardening rule have been implemented, expansion of the techniques to provides more useable design information and allows us to improve the structural integrity of turbine blades, vanes and rotors.

Finite Element Damage Analyses for Predictions of Creep Crack Growth

2010 ◽  
Author(s):  
Chang-Sik Oh ◽  
Nak-Hyun Kim ◽  
Sung-Hwan Min ◽  
Yun-Jae Kim
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Crack Growth ◽  
Damage Mechanics ◽  
Creep Crack Growth ◽  
Creep Damage ◽  
Simulation Method ◽  
Creep Tests ◽  
Creep Ductility ◽  
Creep Crack

This paper provides the virtual simulation method for creep crack growth test, based on finite element (FE) analyses with damage mechanics. Creep tests of smooth bars are used to quantify the constants of creep constitutive equation. The reduction of area resulting from creep tests of smooth and notched bar is adopted as a measure of creep ductility under multiaxial stress conditions. The creep ductility exhaustion concept is adopted for calculating creep damage, which is defined as the ratio of creep strain to the multiaxial creep ductility. To simulate crack propagation, fully damaged elements are forced to have nearly zero stresses using user-defined subroutine UHARD in the general-purpose FE code, ABAQUS. The results from 2D or 3D FE analyses are compared with experimental data of creep crack growth. It is shown that the predictions obtained from this new method are in good agreement with experimental data.

SIE ASME-NH Program for the Structural Integrity Evaluations of a LMR Subjected to Elevated Temperature Operations

2006 ◽  
Author(s):  
Gyeong-Hoi Koo ◽  
Jae-Han Lee
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Structural Integrity ◽  
Creep Damage ◽  
Pressure Vessels ◽  
Step Size ◽  
Time Step ◽  
Time Step Size ◽  
Ratcheting Strain ◽  
Creep Fatigue

In this paper, SIE ASME-NH (Structural Integrity Evaluation by ASME-NH) program, which has a computerized implementation of the details for ASME Pressure Vessels and Piping Code Section III Subsection NH rules including the time-dependent primary stress limits, total accumulated creep ratcheting strain limits, and the creep-fatigue limits for the reactor structures subjected to elevated temperature operations, are described with their detailed application procedures. Using this code, the selected high temperature structures which are subjected to two cycle types are evaluated and the sensitivity studies for the effects of the time step size, primary load, numbers of a cycle, normal temperature on the creep damage evaluations and the effects of the load history on the creep ratcheting strain calculations are investigated. From the selected applications, it is verified that the developed SIE ASME-NH Program is an easy user interface program and it can be an effective tool for the high temperature structural integrity evaluations of LMR.

Research on a New Secondary Creep Model and Creep Damage Evolution for P92 Steel

2013 ◽  
Vol 690-693 ◽  
pp. 157-163 ◽  
Author(s):  
Jun Yuan ◽  
Hong Xu ◽  
Yong Zhong Ni
Keyword(s):  
Experimental Data ◽  
Stress Exponent ◽  
Creep Damage ◽  
Creep Model ◽  
Secondary Creep ◽  
Creep Life ◽  
P92 Steel ◽  
Tertiary Stage ◽  
Creep Constitutive Model ◽  
Damage Equation

In the traditional Norton-Bailey model, the stress exponent is a constant value when the temperature keeps constant, But for some materials, this situation can’t be suitable. Based on the analysis of the experimental data, a secondary creep constitutive model which can be used in the stress exponent changing situation has been proposed. By introducing Kachanov-Rabotnov damage equation, the modified creep model has been established for P92 steel at 610°C and 670°C, which can describe the second and tertiary stage. And the method to determine creep parameters of tertiary stage has been derived. The new model was embedded into ANSYS interface program, and used for calculating the creep life of P92 steel. The results show that the model is in agreement with the experimental data.

Stress Relaxation Damage Analysis for High Temperature Bolting

2012 ◽  
Vol 455-456 ◽  
pp. 1429-1433
Author(s):  
Jin Quan Guo ◽  
Xiao Hong Sun ◽  
Hui Chao Shi
Keyword(s):  
Experimental Data ◽  
High Temperature ◽  
Stress Relaxation ◽  
Life Prediction ◽  
Creep Damage ◽  
Damage Analysis ◽  
Damage Mechanisms ◽  
Life Evaluation ◽  
Relaxation Characteristics ◽  
Life Prediction Model

The paper analyzes the stress relaxation damage mechanisms of high temperature (HT) bolts of ultra-supercritical steam turbine units. Based on creep damage mechanisms and relaxation characteristics, the paper proposes a life prediction model, and by which to predict relaxation damage life of HT bolting material 1Cr10NiMoW2VNbN. Validation results indicate that the developed model has led to better consistent results with experimental data and thus can be recommended in relaxation life evaluation of HT materials.

Sign in / Sign up

Export Citation Format

Share Document