Is it Possible to Get-Rid of S-N Curve for Fatigue Evaluation?: A Fully Mechanistic Model of 316SS Reactor Steel for Fatigue Life Evaluation

2017 ◽  
Author(s):  
Bipul Barua ◽  
Subhasish Mohanty ◽  
William K. Soppet ◽  
Saurindranath Majumdar ◽  
Krishnamurti Natesan
Keyword(s):  
Fatigue Life ◽  
3D Structure ◽  
Cyclic Plasticity ◽  
Fe Model ◽  
Plasticity Model ◽  
Modeling Framework ◽  
Stress Strain ◽  
Life Evaluation ◽  
Fatigue Life Evaluation ◽  
Cyclic Plasticity Model

The present methods for fatigue life evaluation of nuclear reactor components have large uncertainties due to the overdependence on approaches that involve empirical fatigue life estimation, such as use of test-based curves of stress/strain versus life (S∼N) and Coffin-Manson type empirical relations. To reduce the uncertainty in fatigue life evaluation, we are trying to develop a fully mechanistic modeling approach. The aim is to capture the time/cycle-dependent material ageing behavior such as stress hardening/softening through multi-axial stress-strain evolution of the components based on which the life of the component can be predicted. In this paper, we introduce an implementation of the ANL developed evolutionary cyclic plasticity model for 316 SS reactor steel within the commercial finite element (FE) software ABAQUS. A user subroutine is developed to enable the incorporation of the ANL developed evolutionary cyclic plasticity model [1] into ABAQUS. The FE model, developed in this work, can be used for predicting the time-dependent stress hardening/softening of 3D structure. A strain-controlled constant amplitude fatigue experiment scenario is 3D modeled using the developed ABAQUS based FE modeling framework and is verified through experimental data.

scholarly journals A Cyclic-Plasticity-Based Mechanistic Approach for Fatigue Evaluation of 316 Stainless Steel Under Arbitrary Loading

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Bipul Barua ◽  
Subhasish Mohanty ◽  
Joseph T. Listwan ◽  
Saurindranath Majumdar ◽  
Krishnamurti Natesan
Keyword(s):  
Fatigue Life ◽  
Fatigue Loading ◽  
Material Model ◽  
Cyclic Plasticity ◽  
Constant Amplitude ◽  
Stress Strain ◽  
Strain Evolution ◽  
Time Cycle ◽  
Fatigue Evaluation ◽  
Cyclic Plasticity Model

In this paper, a cyclic-plasticity-based fully mechanistic fatigue modeling approach is presented. This is based on time-dependent stress–strain evolution of the material over the entire fatigue life rather than just based on the end of live information typically used for empirical S∼N curve-based fatigue evaluation approaches. Previously, we presented constant amplitude fatigue test based related material models for 316 stainless steel (SS) base, 508 low alloy steel base, and 316 SS-316 SS weld which are used in nuclear reactor components such as pressure vessels, nozzles, and surge line pipes. However, we found that constant amplitude fatigue data-based models have limitation in capturing the stress–strain evolution under arbitrary fatigue loading. To address the aforementioned limitation, in this paper, we present a more advanced approach that can be used for modeling the cyclic stress–strain evolution and fatigue life not only under constant amplitude but also under any arbitrary (random/variable) fatigue loading. The related material model and analytical model results are presented for 316 SS base metal. Two methodologies (either based on time/cycle or based on accumulated plastic strain energy (APSE)) to track the material parameters at a given time/cycle are discussed and associated analytical model results are presented. From the material model and analytical cyclic plasticity model results, it is found that the proposed cyclic plasticity model can predict all the important stages of material behavior during the entire fatigue life of the specimens with more than 90% accuracy.

Description of Closure of Cyclic Stress-Strain Loop and Ratcheting Based on Y-U Model

2016 ◽  
Vol 725 ◽  
pp. 351-356
Author(s):  
Fusahito Yoshida ◽  
Hiroshi Hamasaki ◽  
Takeshi Uemori
Keyword(s):  
Hysteresis Loop ◽  
Kinematic Hardening ◽  
Cyclic Stress ◽  
Cyclic Plasticity ◽  
Plasticity Model ◽  
Stress Strain ◽  
Additional Material ◽  
Material Parameters ◽  
Hardening Law ◽  
Cyclic Plasticity Model

This paper proposes a cyclic plasticity model to describe the closure of a cyclic stress-strain hysteresis loop based on the Y-U model. In this model, the backstress moves in a cyclic memory surface following a newly proposed kinematic hardening law. For this model just the same Y-U parameters can be used, and no additional material parameters are needed. By using a supplementary rule, this model is also able to describe ratcheting.

A Study on Fatigue Life Evaluation of Pressure Vessel Made of ASME SA240-316L Material Using Numerical Analysis

2019 ◽  
Vol 893 ◽  
pp. 1-5 ◽  
Author(s):  
Eui Soo Kim
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Pressure Vessel ◽  
Life Prediction ◽  
Pressure Vessels ◽  
Physical Damage ◽  
Element Analysis ◽  
Internal Damage ◽  
Life Evaluation ◽  
Fatigue Life Evaluation

Pressure vessels are subjected to repeated loads during use and charging, which can causefine physical damage even in the elastic region. If the load is repeated under stress conditions belowthe yield strength, internal damage accumulates. Fatigue life evaluation of the structure of thepressure vessel using finite element analysis (FEA) is used to evaluate the life cycle of the structuraldesign based on finite element method (FEM) technology. This technique is more advanced thanfatigue life prediction that uses relational equations. This study describes fatigue analysis to predictthe fatigue life of a pressure vessel using stress data obtained from FEA. The life prediction results areuseful for improving the component design at a very early development stage. The fatigue life of thepressure vessel is calculated for each node on the model, and cumulative damage theory is used tocalculate the fatigue life. Then, the fatigue life is calculated from this information using the FEanalysis software ADINA and the fatigue life calculation program WINLIFE.

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