bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analytical Study on Seismic Response of Piping Under Multiple Support Excitations
Authors: Kai Satoru , Otani Akihito , Kaneko Naoaki 
Published: August 2013

Conventional response spectrum analysis is used for piping seismic design in Japan. When piping is supported by restraints and structures fixed on multiple buildings or floors, the envelope of the response spectra of all supporting points is typically applied for the piping under multiple excitations. The local vibration mode of long piping is difficult to excite by the far input from the vibrating part, so the analysis will overestimate the response. Considering each input from each building or floor can estimate more reasonable seismic response of the piping. The researches about seismic response analysis by multiple input excitations have been performed since 1960s and the analysis methods are used for piping design in the United State.
There are a few experimental researches to verify the validity of the analysis method by multiple excitations. So an excitation test by multiple excitations planned to verify the validity of the application. This current study was performed as a preliminary investigation for the excitation test and it was to obtain the seismic response of a piping model by multiple excitations. Several kinds of analysis methods are compared and the characteristics of them are discussed.
Influence of Circumferential Flaw Length on Internal Burst Pressure of a Wall-Thinned Pipe
Authors: Tsuji Masataka , Meshii Toshiyuki 
Published: August 2013

The effect of the circumferential angle of a flaw θ on the internal burst pressure pf of pipes with artificial wall-thinned flaws is examined.
When evaluating pf of wall-thinned straight pipes, the effect of θ has been conventionally not regarded as important. Therefore, a burst pressure equation for an axial crack inside a cylinder (Fig. 1, left), such as Kiefner’s equation [1] is widely used [2], [3]. However, it should be noted that there exist the following implicit assumptions when applying the equation for planar flaws to non-planar flaws.
1) The fracture mode of a non-planar flaw under consideration is identical with that of the crack.
2) The effect of θ, which is not considered for an axial crack on pf, is small or negligible.
However, from the systematic burst test results of carbon pipes with artificial wall-thinned flaws, Meshii [4] showed that these implicit assumptions may not be correct. On the other hand, the significance of the effect of the fracture mode on pf and the condition for θ to affect pf are not clear.
Therefore, in this paper, Meshii’s experimental results are evaluated in farther detail. The purpose of the evaluation was set to clarify the effect of θ on pf. Specifically, the significance of flaw configuration (axial length δz and wall-thinning ratio t1/t) was studied in relation to θ and pf. In addition, a simulation of the effect by a Finite Element Analysis (FEA) was attempted.
From the experimental results, θ tended to affect pf in cases with large δz, and t1/t also was correlated to a decrease in pf with the increase of θ. These tendencies were successfully simulated by the elastic-plastic FEA.
This effect means the burst pressure predicted for a crack with identical ligament thickness decreases with the increase of θ, so that the effect by θ on pf should not be ignored.
French Reactor Vessel Integrity
Authors: Churier H. 
Published: August 2013

The French fleet comprises 58 PWR.
The integrity of the reactor pressure vessel is one of the main considerations regarding plant life extension.
The limiting damage is the irradiation embrittlement associated with brittle fracture risk.
During the operation, integrity assessment is updated every 10 years taking in account the knowledge acquired by the feedback. In addition steps have been taken to reduce irradiation. Moreover all the research and development have also led to improvements.
The purpose of the paper, based on the latest updated demonstration of the 3 loops 900 MW vessels for the period 30–40 years of service, is to develop the strategy to be implemented to go beyond 40 years and the progress in each topic.
On one hand the demonstration by analysis is the privileged axis of justification for an operating life of 60 years.
- First, by improving at the maximum deterministic approach with regard to the input data and methods to reduce uncertainties.
- Second, by a complementary probabilistic study with the aim of showing the conservatism of the deterministic approach.
On the other hand, the arrangements already taken during operation for monitoring and mitigating irradiation embrittlement are maintened and reinforced: irradiation surveillance program, in service inspection, limitation and surveillance of fluence, not to mention heating the safety injection water which remains a possibility after the improvements of data and methods.
Design Curve Construction Based on Tolerance Limit Concept
Authors: Wei Zhigang , Dogan Bilal , Luo Limin , Lin Burt , Konson Dmitri 
Published: August 2013

The design curves, such as fatigue design S-N curves, required in engineering designs, are usually constructed by analyzing test data, which often exhibit large scatter. There are many methods available to construct a design curve and many of these methods, with varying degrees of conservativeness, accuracy, and simplicity, have been adopted by engineering standards, codes and guidelines, such as the ASME and ASTM codes and standards. However, to meet the increasing engineering demands, a simplified, user friendly engineering method with rigorous mathematical and physical basis is still urgently needed to accurately manage the margin of safety on one hand and decrease the cost on the other hand.
In this paper the current engineering practices for constructing a design curve is reviewed. It is followed by the tolerance limit concept for general regression cases, because of its capability to relate the design curve to sample size, probability, and confidence level. A simple approximate solution is derived for Owen’s tolerance limit approach, which previously could be solved only with a very complex procedure. Finally, recognizing the physical unsoundness of the hyperbolic shape of the design curves constructed with the Owen’s tolerance limit approach, a new simple design curve construction method is proposed based on the “equal partition principle”. The predicted results from the new method are compared with that of other methods and the advantage of the proposed procedure over other methods is demonstrated with several worked examples. Linear design curve construction with heteroscedastic characteristics (variable variance) and nonlinear design curve are also discussed.
Extreme Value Distribution Theory and its Application in Durability Analysis
Authors: Wei Zhigang , Dong Pingsha , Gao Litang , Kurth Robert 
Published: August 2013

Risk based treatment of degradation and failure in engineering components is an important topic in recent years with an emphasis on obtaining more detailed information for extreme events. Fatigue damage and life degradation caused by variable amplitude cyclic loading is dominated by such extreme events, and can be properly treated with the extreme value theory, which could help understand the damage nature of the fatigue damage process as well as to provide more efficient and robust approaches for engineering applications.
In this paper, advanced extreme value theory is reviewed first. Methods such as peak counting, block maxima, and peaks over thresholds are investigated and compared in this paper with an emphasis on the relationship between the extreme value theory and the existing methods for fatigue life assessment. A few simple examples of uniaxial and multi-axial fatigue life assessment process are provided and the results are discussed. It is found that, if properly used, the extreme value theories can improve the efficiency of fatigue life assessment. Finally, a hybrid time- and frequency-based multi-axial fatigue life assessment procedure is proposed for wide band loadings.
The Adhesion Failure Mode in Stainless Steel Trim Spring Operated Pressure Relief Valves
Authors: Bukowski Julia V. , Gross Robert E. , Goble William M. 
Published: August 2013

This paper addresses dangerous failures of stainless steel (SS) trim spring operated pressure relief valves (SOPRV) due to a particular failure mode (SS-to-SS adhesion) which is not currently being included in SOPRV failure rates. As a result, current methods for estimating or predicting failure rates for SS trim SOPRV significantly underestimate these failure rates and, consequently, overestimate the safety provided by the SOPRV as measured by its average probability of failure on demand (PFDavg) or its corresponding safety integrity level (SIL). The paper also illustrates the critical importance of root cause analysis (RCA) of dangerous SOPRV failures in understanding the impacts of various failure modes.
Over 1300 proof test results for both new and used SS trim SOPRV from the Savannah River Site (SRS) were identified. RCA was used on the failed valves to classify those failed due to SS-to-SS adhesions. Statistical analysis of the data convincingly demonstrates adhesions, previously assumed to be only an in-storage failure phenomenon, are also an in-service failure mode which needs to be included in SOPRV failure rates. The paper discusses the factors which potentially influence the adhesion failure mode and suggests a possible approach to including this mode in failure rate predictions. An example illustrates how current failure rate models overestimate SS trim SOPRV safety by one or two orders of magnitude.
Element Size Dependent Damage Modeling of Ductile Crack Growth in Circumferential Through-Wall Cracked Pipe Tests
Authors: Kim Jong-Hyun , Kim Nak-Hyun , Kim Yun-Jae , Shim Do-Jun 
Published: August 2013

This paper proposes an element-size-dependent damage model to simulate ductile crack growth in full-scale cracked pipes. The proposed method is based on the stress-modified fracture strain damage model modified from stress reduction technique proposed previously by the authors. A modification is made that the critical accumulated damage for progressive cracking is assumed to be dependent on the element size. The proposed method is then compared with a circumferential through-wall cracked pipe test that was conducted during Degrade Piping Program[18].
The bending moment at crack initiation, maximum bending moment, crack extension, and J-integral values were calculated from the FE damage analysis. These results were compared with the experimental results. In addition, results obtained from an existing J-estimation scheme were provided for comparison. All results showed reasonable agreement.
The results of the present study demonstrate that the element-size-dependent damage modeling can be applied to simulate the ductile crack growth behavior of a through-wall cracked pipe.
Influence of Nozzle Transition on Leak Before Break Parameters
Authors: Baas Peter , Blom Frederic 
Published: August 2013

In the framework of leak before break a circumferential through-wall crack in a pipe with nozzle is investigated by means of finite elements and compared to a pipe only geometry. A range of crack angles (3–180°) and inner radius to wall thickness ratios (Ri/t = 5, 10, 20, 50 and 100) have been analysed in order to investigate parameter sensitivity. The nozzle and pipe models are compared for the leak before break parameters stress intensity factor (KI) and Crack Opening Area (COA).
The results of the comparisons are presented as KI nozzle factor (KI nozzle / KI pipe) and COA nozzle factor (COAnozzle / COApipe). At small crack angles the KI nozzle factor is larger than unity, caused by the stress concentration at the nozzle to pipe intersection. At larger crack angles the KI nozzle factor decreases below unity, caused by the so-called bulging effect, which is apparent in the pipe only model. The COA nozzle factor is smaller than unity for all crack angles, caused by the increased stiffness of the nozzle. As the ratio Ri/t increases, both the KI and COA nozzle factors decrease since the nozzle stiffness relative to the pipe increases.
For demonstration of leak before break the nozzle has a negative influence regarding the COA as smaller leaks are more difficult to detect. However, since the KI nozzle factor decreases at larger cracks the influence of nozzles regarding leak before break is not so straight forward.
Small Scale Experiments on Boiling Liquid Expanding Vapor Explosions: Supercritical BLEVE
Authors: Laboureur Delphine , Buchlin Jean-Marie , Rambaud Patrick 
Published: August 2013

The most dangerous accident that can occur in LPG storage is the boiling liquid expanding vapor explosion (BLEVE). To better understand the rupture of the reservoir and the blast wave characteristics, small scale BLEVE experiments are performed with cylinders of 95 ml, filled at 86% with propane, laid horizontally and heated from below. A weakening of the reservoirs on the upper part allows better reproducibility of the rupture. High speed visualization, blast overpressure and surface reservoir temperature are measured.
Internal pressure measurement shows that the rupture pressure and temperature are well above the critical point. The fluid is then supercritical and there is no distinction anymore between liquid and gas prior rupture. This kind of reservoir rupture is significant of a new type of BLEVE, a supercritical BLEVE. The experiments also show that the fluid behavior during rupture differs with the size of the weakened part and therefore with the rupture pressure. Finally, the measured peak overpressures are compared with literature models.
STYLE: Transferability of Fracture Material Properties - Updated Experimental and Analytical Results
Authors: Nicak Tomas , Schendzielorz Herbert , Keim Elisabeth , Meier Gottfried , Moinereau Dominique , Le Delliou Patrick 
Published: August 2013

This paper describes new results of the STYLE study on investigations of transferability of fracture material properties obtained by testing of small scale specimens to a real component.
In STYLE there are three large scale mock-up tests each of them dedicated to investigate specific effects. Mock-up3 (cladded ferritic pipe with the outer diameter of 424 mm) is foreseen to investigate transferability of material data, in particular to compare fracture mechanics behavior of small specimens under different constraint conditions with a full size component. The Mock-Up3 is an original part of a surge line made of low alloy steel (20MnMoNi55 which corresponds to SA 508 Grade 3, Cl. 1).
Usually, material data necessary for fracture mechanic analyses are obtained by testing small specimens, which are subsequently used for the assessment of large scale structures (real components). This approach is believed to be conservative since the material properties are obtained on highly constrained standard specimens.
In this paper new experimental and analytical results will be presented (including tests on constraint modified specimens and a comparison of these results with the Mock-up3 test). The overall objective is to investigate the influence of specimen size, crack shape and type of loading on fracture mechanics properties like crack initiation load or amount of the crack growth by means of numerical analyses and compared with experimental results.
Benchmark Campaign on the Uncertainty Treatment Analysis Tools Developed for French Nuclear Reactor Pressure Vessels Integrity Assessment
Authors: Dautreme Emilie , Beaufils Romain , Pernot Thomas , Remy Emmanuel , Meister Eric , Fontes Jean-Philippe , Demol Thibault , Yalamas Thierry , Defaux Gilles , Izard Jean-Pierre 
Published: August 2013

In France, nuclear reactor pressure vessels (RPV) integrity assessment follows a deterministic methodology and is performed according to the 1999 French regulation requirements with the use of safety coefficients. In the deterministic methodology, the input data are penalized in order to address the uncertainties.
EDF and AREVA developed some couplings between integrity assessment models and uncertainty treatment software in order to address explicitly the uncertainties on the input data.
In such analysis, the accumulation of conservatisms is replaced by a rational combination of parameters taking into account their uncertainty and variability.
This paper presents a benchmark campaign conducted jointly by EDF and AREVA to validate the couplings between the codes and to strengthen the confidence in the calculations.
The benchmark campaign was performed with several physical thermo-mechanical codes and uncertainty treatments software tools to evaluate the sensitivity of the analyses results as a function of code effects. The benchmark results are in good accordance between the several codes used. This conclusion gives confidence in the code couplings used for performing the uncertainty treatment analyses.
Compound and Monobloc Cylinders Incorporating Reverse-Autofrettage to Reduce External Hoop Stresses
Authors: Parker Anthony P. 
Published: August 2013

Reverse autofrettage involves the application of pressure to the OD of a tube which in turn produces bore yielding and a residual stress profile equal in magnitude but opposite in sign to conventional autofrettage.
The analyses within this paper identify two potential new manufacturing procedures involving reverse autofrettage. The procedures are predicted to reduce external tensile hoop stress in an autofrettaged gun tube. This reduction should increase lifetime of tubes that are prone to OD fatigue or corrosion-related failure from manufacturing defects or notches.
The first procedure involves traditional autofrettage of an inner tube and reverse autofrettage of a larger outer tube. The outer tube is then compounded with the inner tube by thermal shrink-fitting or some equivalent process. The second procedure employs a monobloc tube which is subjected to reverse autofrettage followed by conventional internal autofrettage. Both procedures significantly reduce OD residual hoop stress but in the case of the monobloc tube there is an associated loss of compressive residual bore hoop stress.
Ductile Failure Simulation of Bending Pipes With Multiple Circumferential Surface Cracks Using an Element-Size Dependent Damage Model
Authors: Kim Jong-Hyun , Kim Nak-Hyun , Kim Yun-Jae , Hasegawa Kunio , Miyazaki Katsumasa 
Published: August 2013

The purpose of this study is to simulate ductile failure of bending pipes with multiple circumferential surface cracks using an element-size dependent damage model. This method is based on the stress-modified fracture strain damage model with stress reduction technique proposed previously by the authors [9,10]. For validation, simulated results using the proposed method are compared with experimental data of Type 304SS pipes performed by Japanese researchers [19].
To calibrate the proposed method, pipe test data with a single surface crack were compared with simulated results using the damage model. Based on the calibrated damage model, the pipe tests with multiple circumferential surface cracks were simulated. The bending moment at both crack penetration and coalescence were calculated from the FE damage analysis. These results were compared with the experimental results.
In spite of its simplicity, the results show that proposed method can simulate ductile failure behavior of bending pipes with multiple circumferential surface cracks.
Kendall Analysis of Cannon Pressure Vessels
Authors: Underwood John H. 
Published: August 2013

Engineering mechanics analysis of cannon pressure vessels is described with special emphasis on the work of the late US Army Benet Laboratories engineer David P. Kendall. His work encompassed a broad range of design and analysis of high pressure vessels for use as cannons, including analysis of the limiting yield pressure for vessels, the autofrettage process applied to thick vessels, and the fatigue life of autofrettaged cannon vessels. Mr. Kendall’s work has become the standard approach used to analyze the structural integrity of cannon pressure vessels at the US Army Benet Laboratories.
The methods used by Kendall in analysis of pressure vessels were simple and direct. He used classic results from research in engineering mechanics to develop descriptive expressions for limiting pressure, autofrettage residual stresses and fatigue life of cannon pressure vessels. Then he checked the expressions against the results of full-scale cannon pressure vessel tests in the proving grounds and the laboratory. Three types of analysis are described: [i] Yield pressure tests of cannon sections compared with a yield pressure expression, including in the comparison post-test yield strength measurements from appropriate locations of the cannon sections; [ii] Autofrettage hoop residual stress measurements by neutron diffraction in cannon sections compared with expressions, including Bauschinger corrections in the expressions to account for the reduction in compressive yield strength near the bore of an autofrettaged vessel; [iii] Fatigue life tests of cannons following proving ground firing and subsequent laboratory simulated firing compared with Paris-based fatigue life expressions that include post-test metallographic determination of the initial crack size due to firing. Procedures are proposed for Paris life calculations for bore-initiated fatigue affected by crack-face pressure and notch-initiated cracking in which notch tip stresses are significantly above the material yield strength.
The expressions developed by Kendall and compared with full-scale cannon pressure vessel tests provide useful first-order design and safety checks for pressure vessels, to be followed by further engineering analysis and service simulation testing as appropriate for the application. Expressions are summarized that are intended for initial design calculations of yield pressure, autofrettage stresses and fatigue life for pressure vessels. Example calculations with these expressions are described for a hypothetical pressure vessel.