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Journal Articles

Effect of excessive compressive loading on crack growth behavior

Yamaguchi, Yoshihito; Li, Y.*; Sugino, Hideharu*; Katsuyama, Jinya; Onizawa, Kunio

Nihon Kikai Gakkai Rombunshu, A, 78(789), p.613 - 617, 2012/05

In recent years, Japanese nuclear power plants experienced multiple large earthquakes, such as Niigata-ken Chuetsu-Oki Earthquake in 2007 and the Tohoku District - off the Pacific Ocean Earthquake in 2011. Therefore, it is very important to assess the structural integrity of reactor piping under such a large earthquake when a crack exists in the piping. In this study, an effect of excessive compressive loading on the crack growth behavior of piping materials has been evaluated through cracked plate testing. It was observed that excessive compressive loading had an acceleration effect on crack growth rate. The evaluation method using J-integral to evaluate the crack growth behavior under the condition beyond small-scale yielding has been proposed for the acceleration effect of excessive compressive loading on crack growth rate. It was indicated that the acceleration effect by excessive compressive loading simulating a large earthquake could be evaluated using the proposed method.

Journal Articles

A Proposal for evaluation method of crack growth due to cyclic overload for piping materials based on an elastic-plastic fracture mechanics parameter

Yamaguchi, Yoshihito; Li, Y.*; Sugino, Hideharu*; Katsuyama, Jinya; Onizawa, Kunio

Nihon Kikai Gakkai Rombunshu, A, 77(777), p.685 - 689, 2011/05

The magnitude of Niigata-ken Chuetsu-Oki earthquake in 2007 was beyond the assumed one provided in seismic design. Therefore it becomes an important issue to evaluate the crack growth behaviors due to the cyclic overload like large earthquake. Fatigue crack growth is usually evaluated by Paris's law using the range of stress intensity factor ($$Delta$$K). However, $$Delta$$K is inappropriate in a loading condition beyond small scale yielding. In this study, the crack growth behaviors for piping materials were investigated based on an elastic-plastic fracture mechanics parameter, J-integral. It was indicated that the crack growth due to the cyclic overload beyond small scale yielding could be the sum of fatigue and ductile crack growth. The retardation effect of excessive loading on the crack growth was observed after the loading. The modified Wheeler model using J-integral has been proposed for the prediction of retardation effect. Finally, an evaluation method for crack growth behaviors due to the cyclic overload was suggested.

Journal Articles

Investigation on evaluation method based on J integral for retardation of crack growth due to excessive loading beyond small scale yielding condition

Yamaguchi, Yoshihito; Katsuyama, Jinya; Onizawa, Kunio; Sugino, Hideharu*; Li, Y.*

Proceedings of 2010 ASME Pressure Vessels and Piping Conference (PVP 2010) (CD-ROM), 8 Pages, 2010/07

Niigata-ken Chuetsu-Oki earthquake occurred, whose magnitude was beyond the assumed one provided in seismic design. Therefore it becomes an important issue to evaluate the effect of such an excessive loading. Fatigue crack growth is usually evaluated by Paris's law using the range of stress intensity factor, $$Delta$$K. However, since $$Delta$$K is inappropriate in a loading condition beyond the small scale yielding, the evaluation method for such a loading condition should be established. In this study, the crack growth behaviors were investigated using austenitic stainless steel and carbon steel. Instead of $$Delta$$K, the range of J-integral, $$Delta$$J, has been used for the interpretation of experimental data. Applicability of $$Delta$$J into the Wheeler model, which express the retardation effect on the crack growth, has been proposed to evaluate the retardation effect. It was indicated that the J-Wheeler model could be applied to predict the crack growth after an excessive loading beyond small scale yielding.

Journal Articles

Experimental and analytical studies on the effect of excessive loading on fatigue crack propagation in piping materials

Yamaguchi, Yoshihito; Katsuyama, Jinya; Onizawa, Kunio; Sugino, Hideharu*; Li, Y.*; Yagawa, Genki*

Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 9 Pages, 2009/07

Niigata-ken Chuetsu-oki earthquake was actually happened, whose magnitude was beyond the assumed one provided in seismic design, in July 2007. Through these events, it is becoming the focus of attention to evaluate an effect of large scale earthquake while the SCC and/or fatigue-crack are assumed to piping. Many previous papers have been already published about the retardation effect on fatigue crack growth by excessive loading. The retardation effect is treated qualitatively relating to plastic strain generated by excessive loading. In this work, the crack growth after the excessive loading is evaluated for carbon steel and austenitic stainless steel. Some cyclic excessive loading patterns such as stepwise increase or decrease were applied to fatigue-crack-growth experiments. The FEM analyses were conducted to evaluate the plastic region size during such loading conditions. The PFM analyses were conducted to evaluate the retardation of crack growth influence the probability of failure.

Journal Articles

Limit load estimation method for pipe with an arbitrary shaped circumferential surface flaw

Li, Y.*; Hasegawa, Kunio*; Onizawa, Kunio; Sugino, Hideharu*

Nihon Kikai Gakkai Rombunshu, A, 75(752), p.469 - 475, 2009/04

When a flaw is detected in a pipe during in-service inspection, the limit load criterion given in the standards such as JSME Rules on Fitness-for-Service for Nuclear Power Plants or ASME Boiler and Pressure Vessel Code Sec. XI is applied to evaluate the integrity of the pipe. However, in the present standards, the limit load criterion is only provided for the case of a flaw with the uniform depth, although many flaws with complicated shape such as stress corrosion cracking have been actually detected in a pipe. In this paper, a limit load estimation method for a circumferential surface flaw with arbitrary shape is proposed, in order to evaluate the integrity of the pipe for the practical case. The plastic collapse moment and stress are obtained by dividing the surface flaw into several segmented sub-flaws. Using this method, good agreement is observed between the numerical solution and reported experimental results. It is shown that the number of the segmented sub-flaws for the semi-elliptical surface flaw is sufficient to be three from engineering judgment.

Journal Articles

Fracture estimation method for pipe with multiple circumferential surface flaws subjected to bending

Li, Y.*; Sugino, Hideharu*; Hasegawa, Kunio*; Onizawa, Kunio; Doi, Hiroaki*; Ebisawa, Katsumi*

Nihon Kikai Gakkai Rombunshu, A, 75(749), p.56 - 63, 2009/01

When a flaw is detected in a stainless steel pipe during in-service inspection, the limit load criterion given in the standards such as JSME Rules on Fitness-for-Service for Nuclear Power Plants or ASME Boiler and Pressure Vessel Code Section XI can be applied to evaluate the integrity of the pipe. However, in the present standards, the limit load criterion is only provided for the case of single flaw, although multiple flaws such as stress corrosion cracking have been detected in the same circumferential cross section in a pipe. In this paper, a fracture estimation method is proposed based on the limit load criterion for multiple independent circumferential surface flaws with arbitrary number and distribution, to evaluate the integrity of the pipe in a rational way. Several numerical examples are given to show the validity of this method.

Journal Articles

Development of structural reliability evaluation method for aged piping considering uncertainties of seismic motions; How to evaluate the failure probability of aged piping in nuclear power plant due to earthquake

Ito, Hiroto; Onizawa, Kunio; Sugino, Hideharu*

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 50(7), p.434 - 437, 2008/07

Magnitude of seismic motion and degradation such as crack initiation and growth on stress corrosion cracking have uncertainties in the evaluation for the structural integrity of reactor components under seismic motion. We have studied evaluation methods for the structural integrity of components such as piping, i.e. failure probabilities in operation time by probabilistic fracture mechanics (PFM) analysis method which evaluates the uncertainties quantitatively. The evaluation method for seismic motion considering uncertainties, which is most important to evaluate the safety of nuclear power plants under seismic motion, has also been developed. Though their evaluation methods were independent in past, we developed the evaluation method for the failure probabilities considering occurrence probabilities of seismic motion around a plant when seismic motion acts on aged piping by merging them together.

Journal Articles

Development of seismic load evaluation code for evaluating structural reliability of nuclear components

Sugino, Hideharu; Komori, Yoshihisa*; Onizawa, Kunio; Suzuki, Masahide

Nihon Genshiryoku Gakkai Wabun Rombunshi, 5(2), p.118 - 124, 2006/06

To establish the reliability evaluation method for nuclear components, we developed a probabilistic seismic hazard evaluation code SHEAT-FM (Seismic Hazard Evaluation for Assessing the Threat to a facility site - Fault Model) using a seismic motion prediction method based on fault model. The seismic motion prediction method is usually used for defined fault. In this code, we propose to apply this method for undefined fault in the seismic hazard evaluation. This report describes the outline of SHEAT-FM code and sample problem for a model site, and result of the comparison of seismic hazard curves using fault model and attenuation relationship.

JAEA Reports

Analysis of phase property of earthquakes observed by vertical instrument arrays at JAEA Oarai site

Sugino, Hideharu*; Onizawa, Kunio

JAEA-Data/Code 2006-005, 43 Pages, 2006/03

JAEA-Data-Code-2006-005.pdf:1.52MB

Regression models of group delay time have been established by analyzing Earthquake Observation database obtained from Vertical Instrument Arrays at the Oarai Research and Development Center of Japan Atomic Energy Agency. It is known that the mean value and standard deviation of group delay time obtained by differentiating the Fourier phase spectrum show the center of gravity position and continuous time in earthquake time history. Therefore the regression model of the mean value and standard deviation of group delay time was made as function of the magnitude and the epicentral distance. This model includes the source and propagation of earthquake around the site. It is expected that the development of seismic motion prediction method considering the site's phase property by using this regression model.

JAEA Reports

User's manual of a computer code for evaluating effectiveness of seismic component base isolation, EBISA; Function of dynamic response analysis code

Tsutsumi, Hideaki*; Sugino, Hideharu*; Onizawa, Kunio; Mori, Kazunari*; Yamada, Hiroyuki*; Shibata, Katsuyuki; Ebisawa, Katsumi*

JAEA-Data/Code 2006-004, 167 Pages, 2006/03

JAEA-Data-Code-2006-004.pdf:6.41MB

EBISA (Equipment Base Isolation System Analysis) code evaluates the effectiveness of seismic isolation for the important components in the seismic safety, and consists of the three codes, probabilistic seismic hazard code (SHEAT), seismic dynamic response analysis code (RESP) and seismic failure probability and frequency evaluation code. In these codes, RESP code is used for the calculation of the dynamic response behavior of a nuclear component with seismic isolation devices. This report describes the overall explanation of EBISA, and user's guide of RESP code including the analysis function, input manual and sample problem.

Journal Articles

Development of structural reliability evaluation method for aged piping considering uncertainty of seismic motions

Sugino, Hideharu*; Ito, Hiroto*; Onizawa, Kunio; Suzuki, Masahide

Nihon Genshiryoku Gakkai Wabun Rombunshi, 4(4), p.233 - 241, 2005/12

The purpose of this research is to establish the reliability evaluation method of aged nuclear power components for seismic events from a viewpoint of long-term use of the existing light water reactor nuclear power plants. For this purpose, we developed a piping failure probability evaluation code "PASCAL-SC" based on probabilistic fracture mechanics, and a probabilistic seismic hazard evaluation code "SHEAT-FM" for calculating the seismic occurrence probability of a plant site, paying attention to aging such as fatigue crack progress by the stress corrosion cracking and seismic load in primary coolant piping system. We proposed the reliability evaluation method of aged piping for seismic events by combination of these codes. Using this method, we evaluated the reliability of a weld line in the PLR(Primary Loop Recirculation system) piping of the BWR model plant for seismic events.

JAEA Reports

User's manual of a computer code for Seismic Hazard Evaluation for Assessing the Threat to a facility by Fault Model; SHEAT-FM

Sugino, Hideharu*; Onizawa, Kunio; Suzuki, Masahide

JAERI-Data/Code 2005-008, 95 Pages, 2005/09

JAERI-Data-Code-2005-008.pdf:3.46MB

To establish the reliability evaluation method for aged structural component, we developed a probabilistic seismic hazard evaluation code SHEAT-FM (Seismic Hazard Evaluation for Assessing the Threat to a facility site; Fault Model) using a seismic motion prediction method based on fault model. In order to improve the seismic hazard evaluation, this code takes the latest knowledge in the field of earthquake engineering into account. For example, the code involves a group delay time of observed records and an update process model of active fault. This report describes the user's guide of SHEAT-FM, including the outline of the seismic hazard evaluation, specification of input data, sample problem for a model site, system information and execution method.

Oral presentation

A Proposal for evaluation method of crack growth due to cyclic overload for piping materials based on an elastic-plastic fracture mechanics parameter

Yamaguchi, Yoshihito; Li, Y.*; Sugino, Hideharu*; Katsuyama, Jinya; Onizawa, Kunio

no journal, , 

Niigata-ken Chuetsu-Oki earthquake occurred, whose magnitude was beyond the assumed one provided in seismic design. Therefore it becomes an important issue to evaluate the crack growth behaviors due to the cyclic overload like large earthquake. Fatigue crack growth is usually evaluated by Paris's law using the range of stress intensity factor ($$Delta$$K). However, $$Delta$$K is inappropriate in a loading condition beyond small scale yielding. In this study, the crack growth behaviors for piping materials were investigated based on an elastic-plastic fracture mechanics parameter, J-integral. It was indicated that the crack growth due to the cyclic overload beyond small scale yielding could be the sum of fatigue and ductile crack growth. The retardation effect on the crack growth was observed after excessive loading. The modified Wheeler model using J-integral has been proposed for the prediction of retardation effect. Finally, an evaluation method for crack growth behaviors due to the cyclic overload was suggested.

Oral presentation

Effect of excessive compressive loading on the crack growth behavior

Yamaguchi, Yoshihito; Li, Y.*; Sugino, Hideharu*; Katsuyama, Jinya; Onizawa, Kunio

no journal, , 

In recent years, Japanese nuclear power plants experienced multiple large earthquakes, such as Niigata-ken Chuetsu-Oki Earthquake in 2007 and the Great East Japan Earthquake in 2011. Therefore, it is very important to assess the structural integrity of reactor piping under such a large earthquake when a crack exists in the piping. In this work, An effect of excessive compressive loading on the crack growth behavior of piping materials has been studied through cracked plate testing. It was observed that excessive compressive loading had an acceleration effect on crack growth rate. The evaluation method using J-integral has been proposed for the acceleration effect of crack growth rate. It was indicated that the acceleration effect by excessive compressive loading for the condition beyond small-scale yielding could be conservatively evaluated using the proposed method.

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