Modelling the manufacturing history, through life creep-fatigue damage and limiting defect sizes of a pipework joint using finite element based methods

2013 ◽  
Vol 108-109 ◽  
pp. 13-27 ◽  
Author(s):  
M.J. Stevens ◽  
R.J. Dennis ◽  
I.J.M. Bottomley ◽  
R.A.W. Bradford
Author(s):  
D. P. Bray ◽  
R. J. Dennis ◽  
R. A. W. Bradford

The work reported in this paper investigates the complex manufacture and through-life operation of a pipework joint in a UK AGR boiler. Residual stresses resulting from the fabrication process can be a key driver for creep and creep-fatigue damage. The calculation of creep-fatigue damage for assessment purposes is typically undertaken within the framework of an appropriate assessment code (such as British Energy’s R5). The standard assessment approach usually requires the undertaking of elastic finite element analysis followed by Neuber construction to convert elastic stress ranges into elastic-plastic stress and strain ranges prior to the calculation of creep-fatigue damage. A combination of explicit and implicit finite element methods are employed in order to simulate a range of manufacturing processes which influence the material state for a branched pipework joint. The solution is effectively obtained within one finite element model, with re-meshing performed where necessary. This solution then feeds into a finite element based structural integrity assessment. The methods utilise the principles outlined in the British Energy R5 assessment code but utilise the inelastic strains calculated directly from analysis. The methods are based around the general purpose finite-element code Abaqus enhanced by the use of user-defined subroutines CREEP and UVARM. This paper describes analyses performed to simulate the complex manufacturing history of a branched pipework component, and to estimate its subsequent in service creep-fatigue damage using finite element based methods.


2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Hyeong-Yeon Lee ◽  
Kee-Nam Song ◽  
Yong-Wan Kim ◽  
Sung-Deok Hong ◽  
Hong-Yune Park

A process heat exchanger (PHE) transfers the heat generated from a nuclear reactor to a sulfur-iodine hydrogen production system in the Nuclear Hydrogen Development and Demonstration, and was subjected to very high temperature up to 950°C. An evaluation of creep-fatigue damage, for a prototype PHE, has been carried out from finite element analysis with the full three dimensional model of the PHE. The inlet temperature in the primary side of the PHE was 950°C with an internal pressure of 7 MPa, while the inlet temperature in the secondary side of the PHE is 500°C with internal pressure of 4 MPa. The candidate materials of the PHE were Alloy 617 and Hastelloy X. In this study, only the Alloy 617 was considered because the high temperature design code is available only for Alloy 617. Using the full 3D finite element analysis on the PHE model, creep-fatigue damage evaluation at very high temperature was carried out, according to the ASME Draft Code Case for Alloy 617, and technical issues in the Draft Code Case were raised.


Author(s):  
Hyeong-Yeon Lee ◽  
Kee-Nam Song ◽  
Yong-Wan Kim ◽  
Sung-Deok Hong ◽  
Hong-Yune Park

A process heat exchanger (PHE) transfers the heat generated from a nuclear reactor to a sulfur-iodine hydrogen production system in the NHDD (Nuclear Hydrogen Development and Demonstration), and was subjected to very high temperature up to 950°C. An evaluation of creep-fatigue damage, for a prototype PHE, has been carried out from finite element analysis with the full three dimensional model of the PHE. The inlet temperature in the primary side of the PHE was 950°C with an internal pressure of 7MPa while the inlet temperature in the secondary side of the PHE is 500°C with internal pressure of 4MPa. The candidate materials of the PHE were Alloy 617 and Hastelloy X. In this study, only the Alloy 617 was considered because the high temperature design code is available only for Alloy 617. Using the full 3D finite element analysis on the PHE model, creep-fatigue damage evaluation at very high temperature was carried out, according to the ASME Draft Code Case for Alloy 617, and technical issues in the draft Code Case were raised.


1992 ◽  
Vol 114 (2) ◽  
pp. 152-160 ◽  
Author(s):  
A. Dasgupta ◽  
C. Oyan ◽  
D. Barker ◽  
M. Pecht

This study explores the possibility of using a unified theory of creep-fatigue, similar to the Halford-Manson strain-range partitioning method, for examining the effect of cyclic temperature range on fatigue life, over a wide range of temperatures. Other investigators have attempted similar techniques before for solder fatigue analysis. The present study is different since it proposes an energy-partitioning technique rather than strain-partitioning to examine the dependence of solder fatigue behavior on temperature dependent changes in the relative amounts of plastic and creep strains. The solder microstructure also dictates creep behavior but is assumed to be a given invariant parameter in this study. In other words, this study is targeted at as-cast microstructures and does not address post-recrystallization behavior. A sample solder joint of axisymmetric configuration, commonly found in leaded through-hole mounting technology, is analyzed with the help of nonlinear finite element methods. The strain history is determined for constant-amplitude temperature cycling with linear loading and unloading, and with constant dwells at upper and lower ends of the cycle. Large-deformation continuum formulations are utilized in conjunction with a viscoplastic constitutive model for the solder creep-plasticity behavior. Relevant material properties are obtained from experimental data in the literature. The results show significant amounts of rachetting and shakedown in the solder joint. Detailed stress-strain histories are presented, illustrating the strain amplitude, mean strain and residual stresses and strains. For illustrative purposes, the hysteresis cycles are partitioned into elastic, plastic and creep components. Such partitioned histories are essential in order to implement either the Halford-Manson strain-range partitioning technique or the energy-based approach suggested here, for analyzing the creep-fatigue damage accumulation in solder material. This study also illustrates the role and utility of the finite element method in generating the detailed stress-strain histories necessary for implementing the energy partitioning approach for creep-fatigue damage evaluation. Solder life prediction is presented as a function of cyclic temperature range at a given mean temperature.


2015 ◽  
Vol 19 (5) ◽  
pp. 563-570 ◽  
Author(s):  
Ridha Hambli ◽  
Sana Frikha ◽  
Hechmi Toumi ◽  
João Manuel R. S. Tavares

2021 ◽  
Vol 173 ◽  
pp. 112830
Author(s):  
Wenhai Guan ◽  
Hyoseong Gwon ◽  
Takanori Hirose ◽  
Hisashi Tanigawa ◽  
Yoshinori Kawamura ◽  
...  
Keyword(s):  

Author(s):  
N. A. Zentuti ◽  
J. D. Booker ◽  
R. A. W. Bradford ◽  
C. E. Truman

An approach is outlined for the treatment of stresses in complex three-dimensional components for the purpose of conducting probabilistic creep-fatigue lifetime assessments. For conventional deterministic assessments, the stress state in a plant component is found using thermal and mechanical (elastic) finite element (FE) models. Key inputs are typically steam temperatures and pressures, with the three principal stress components (PSCs) at the assessment location(s) being the outputs. This paper presents an approach which was developed based on application experience with a tube-plate ligament (TPL) component, for which historical data was available. Though both transient as well as steady-state conditions can have large contributions towards the creep-fatigue damage, this work is mainly concerned with the latter. In a probabilistic assessment, the aim of this approach is to replace time intensive FE runs with a predictive model to approximate stresses at various assessment locations. This is achieved by firstly modelling a wide range of typical loading conditions using FE models to obtain the desire stresses. Based on the results from these FE runs, a probability map is produced and input(s)-output(s) functions are fitted (either using a Response Surface Method or Linear Regression). These models are thereafter used to predict stresses as functions of the input parameter(s) directly. This mitigates running an FE model for every probabilistic trial (of which there typically may be more than 104), an approach which would be computationally prohibitive.


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