Volume 6A: Materials and Fabrication最新文献

{"title":"XFEM and Standard Fracture-Mechanics Analyses of the Reactor Pressure Vessel Gösgen Based on Thermal-Hydraulics Input Data From KWU-MIX and CFD Analyses","authors":"Alexander Mutz, T. Nicak, R. Trewin, I. Cremer","doi":"10.1115/pvp2019-93564","DOIUrl":"https://doi.org/10.1115/pvp2019-93564","url":null,"abstract":"\u0000 The integrity of a reactor pressure vessel (RPV) has to be ensured throughout its entire life in accordance with the applicable regulations. Typically an assessment of the RPV against brittle failure needs to be conducted by taking into account all possible loading cases. One of the most severe loading cases, which can potentially occur during the operating time, is the loss-of-coolant accident, where cold water is injected into the RPV at operating conditions. High pressure in combination with a thermal shock of the ferritic pressure vessel wall caused by the injection of cold water leads to a considerable load at the belt-line area known as Pressurized Thermal Shock (PTS).\u0000 Usually the assessment against brittle failure is based on a deterministic fracture-mechanics analysis, in which common parameters like J-integral or stress intensity factor are employed to calculate the load path for an assumed (postulated) flaw during the PTS event. As an alternative to this standard approach a fracture mechanics assessments based on eXtended Finite Element Method (XFEM) approach can be performed.\u0000 The most important input data for the fracture-mechanics analysis is the transient thermal-hydraulics (TH) load of the RPV during the emergency cooling. Such data can be calculated by analytical fluid-mixing codes verified on experiments, such as KWU-MIX, or by numerical Computational Fluid Dynamics (CFD) tools after suitable validation. In KWU-MIX, which is the standard used for TH calculations within PTS analyses, rather conservative analytical models for the quantification of mixing and, depending on the water level, condensation processes in the downcomer (including simplified stripe and plume formations) are utilized. On the contrary, the numerical CFD tools can provide best-estimate results due to the possibility to consider more realistically the stripe and plume formations as well as the geometry of the RPV in detail.\u0000 In a previous paper [1] results of standard and XFEM analyses of the RPV Gösgen 1 based on thermal-hydraulics input data from KWU-MIX were presented. This paper presents new results based on thermal-hydraulics input data from CFD. The new results are compared with those from [1] in order to show additional safety margins obtained by using thermal-hydraulics input data from CFD.","PeriodicalId":428760,"journal":{"name":"Volume 6A: Materials and Fabrication","volume":" 7","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113946227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing Low-Constraint Fracture Toughness Test Methods Using Clamped SENT Specimens","authors":"Xian-Kui Zhu, T. Mcgaughy","doi":"10.1115/pvp2019-93088","DOIUrl":"https://doi.org/10.1115/pvp2019-93088","url":null,"abstract":"\u0000 The low-constraint fracture toughness can be measured using a single edge-notched tension (SENT) specimen in the clamped-end conditions. The SENT specimen has been used in the oil and gas industry in the strain-based design and the crack assessment for transmission pipelines. Since 2006 when DNV published the first SENT test practice, many investigations have been done, and various SENT test methods were developed, including CANMET and ExxonMobil methods in terms of the J-integral and CTOD. The effort led to the first SENT test standard BS 8571 being published in 2014. However, the experimental evaluation methods remain in developing, and different methods may determine inconsistent results. For this reason, the present paper gives a brief review on SENT fracture testing and assesses the available test methods, including progresses on study of stress intensity factor, geometric eta factors, elastic compliance equation, and constraint m factor as well. The difference between J-converted CTOD and double clip gage measured CTOD is also discussed. On those bases, agreements and challenges in SENT testing are identified. The results provide a direction for further investigation to improve the current SENT test methods.","PeriodicalId":428760,"journal":{"name":"Volume 6A: Materials and Fabrication","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131491435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Plasticity on Creep Deformation in Type 316H Stainless Steel","authors":"A. Mamun, C. Simpson, T. Erinosho, D. Agius, C. Reinhard, M. Mostafavi, D. Knowles","doi":"10.1115/pvp2019-93587","DOIUrl":"https://doi.org/10.1115/pvp2019-93587","url":null,"abstract":"\u0000 The creep life and deformation behaviour of high-temperature steels can be significantly affected by the prior plastic loading. This effect is partly due to the generation of intergranular strains from the grain-scale elastic and plastic anisotropic deformation during plastic loading. This paper investigates the effect of these plasticity generated intergranular strains on the subsequent creep strain accumulation behavior in type 316H stainless steel. An in-situ synchrotron diffraction experiment was conducted at 550°C, where the sample was loaded incrementally to different magnitudes of plastic strain, followed by a displacement-controlled stress relaxation dwell at each of this stage. The lattice strains of 4 grain families were measured during these stages. It was found that the intergranular strains generated during the plastic deformation significantly affect the relative magnitude of creep strain accumulation in different grain families. A subtle but significant difference has been observed between the creep intergranular strain accumulation behavior and the plastic intergranular strain accumulation behavior in different grain families which can be used to interrogate the validity of any micromechanical models’ formulation for creep and plastic deformation. The macroscopic stress relaxations measured from the experiment were compared with the prediction from a novel crystal plasticity based micromechanical model developed in our group. A good overall match was found between the experiment and the model regarding the magnitude of stress relaxation after various level of plasticity. The experiments have demonstrated that the model requires further development to accurately predict the rate of stress relaxation and the micro scale lattice strain evolution during creep.","PeriodicalId":428760,"journal":{"name":"Volume 6A: Materials and Fabrication","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131420592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fractography Study of the Mixed Mode Fatigue Crack Growth Process in Pressure Vessel P355NL1 Steel","authors":"G. Lesiuk, J. Correia, M. Smolnicki, W. Błażejewski, M. Seghier, A. Jesus, R. Calçada","doi":"10.1115/pvp2019-94062","DOIUrl":"https://doi.org/10.1115/pvp2019-94062","url":null,"abstract":"\u0000 The aim of the paper is to present a fatigue crack growth analysis thru a fractography study of different crack paths obtained in different operating conditions of the pressure vessel P355NL1 steel. All experiments were performed on CTS (Compact Tension Shear) specimens under the mixed mode (I+II) loading conditions. These stress states aim to reflect simple biaxiality stress states in a pressurized cylinder. In the experiments, different operating conditions were considered. Two different kinetic fatigue fracture diagrams were proposed for mixed mode fatigue crack growth rate estimation. The obtained results suggested a fact that energy approach describes synonymously the kinetics of fatigue crack growth under mixed mode loading conditions with respect to the mean stress effect – R-ratio. Finally, the fractography analysis sugessted that the fatigue fracture surface topography changes with the mixity level.","PeriodicalId":428760,"journal":{"name":"Volume 6A: Materials and Fabrication","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115446090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modification of the MPC Omega Model to Predict Primary and Tertiary Creep","authors":"M. Haque","doi":"10.1115/pvp2019-93100","DOIUrl":"https://doi.org/10.1115/pvp2019-93100","url":null,"abstract":"\u0000 The MPC Omega model has become popular in recent years for the prediction of creep deformation. Successful predictions of the tertiary creep for a wide range of materials are available. The Omega model relates the strain as a linear function of the natural logarithm of strain-rate. It is assumed that the primary creep is a short-lived phenomenon and can be neglected. The Omega model is unable to predict the primary creep deformation. Often primary creep is a long-lived phenomenon and cannot be neglected. A mathematical modification can be performed to incorporate the primary creep curve in the Omega model. A common approach is by adding a work hardening function to the original constitutive model. Approaches using power, or exponential, or logarithmic work-hardening function are available. However, it is difficult to discern which function is the best for accurate prediction. In this study, the Omega model is modified to predict the primary and tertiary creep deformation curve by adding a hyperbolic tangent work hardening function. A metamodel incorporating the four modified Omega sub-models (power, exponential, logarithmic and hyperbolic tangent) is developed. The metamodel enables the determination of the most suitable model for a given material and avoids the force fit of a preselected model. Short, medium, and long-term creep deformation data for alloy P91 (pipe) and G91 (plate) at two isotherms of 600°C and 650°C are used to calibrate the metamodel. The data include five stress levels ranging from 70 to 160 MPa including creep life from 233 to 1.1 × 105 hrs. A detail calibration process is provided. A numerical analysis is performed to compare the four submodels. It is observed that the selection of the most suitable function depends on the loading condition and material properties. Based on the analysis, a recommendation to select the suitable work-hardening function to predict the primary and tertiary creep deformation curve is presented.","PeriodicalId":428760,"journal":{"name":"Volume 6A: Materials and Fabrication","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128267438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Failure Assessment Using XFEM for the Austenitic Stainless Steel Pipe With the Circumferential Crack Subjected to Bending and Torque","authors":"Yohei Ono, M. Sakai","doi":"10.1115/pvp2019-93240","DOIUrl":"https://doi.org/10.1115/pvp2019-93240","url":null,"abstract":"\u0000 Failure assessment of a pipe with a circumferential crack in a nuclear power plant has to conform to the Rules on Fitness for Service for Nuclear Power Plants published by JSME (The Japan Society of Mechanical Engineering) [1] in Japan. Based on the rules, the applied stresses considered in the failure assessment of the pipe using limit load assessment are membrane, bending, and thermal stresses. The failure assessment focuses only on mode I. In actual plants, depending on the piping system, there is a possibility that torsional stress [2] is applied to the pipe, in addition to membrane, bending, and thermal stresses. Under such a load condition, the crack opening mode will be mixed-mode. In ASME Boiler & Pressure Vessel Code section XI, the bending and torsional moment are considered in failure assessment of the pipe. Therefore, it is important to establish the failure assessment method for the pipe with the crack under mixed-mode. In this study, the XFEM (extended Finite Element Method) [3][4] was applied to assess failure of the austenitic stainless steel pipe (Type 304) with a circumferential crack subjected to bending and torsional moment. XFEM does not require elemental division considering the crack shape and its propagation path. Therefore, the time and cost for developing the analysis model can be reduced compared with conventional FEA (Finite Element Analysis). Fracture test results conducted under two conditions were used the analysis (Specimen No. TP1 and TP2) for determining the energy release rate for crack propagation and verifying the analysis results. The difference between the two tests was the ratio of torsional moment to bending moment. The ratios in TP1 and TP 2 were 0.6 and 1.2, respectively. A parametric analysis was conducted to determine the critical equivalent strain energy release rate required for crack initiation and propagation by comparison with TP1 results. The determined critical equivalent strain energy release rate was verified by comparison with TP2 results. In response to the above considerations, the decreasing load due to crack propagation in the fracture tests under mixed-mode condition was simulated by XFEM, and the maximum load, bending moment, and torsional moment were predicted within the margin of error of 6.1%.","PeriodicalId":428760,"journal":{"name":"Volume 6A: Materials and Fabrication","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128781040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ultrasonic Phased Array Inspection With Water Wedge for Butt Fusion Joints of Polyethylene Pipe","authors":"Miao Cunjian, Yinkang Qin, Guo Weican, C. An, Z. Ling, Zhifa Chen","doi":"10.1115/pvp2019-93500","DOIUrl":"https://doi.org/10.1115/pvp2019-93500","url":null,"abstract":"\u0000 Polyethylene pipe has been used widely in gas transportation and nuclear safety-related cooling water applications due to its exceptional resistance to corrosion and erosion. Butt fusion joint is one of the main welding forms for polyethylene pipes. Ultrasonic technique is a typical nondestructive examination technique. To overcome the coupling problems when inspecting butt fusion structures, an inspection technique of ultrasonic phased array using water wedge is proposed to solve the coupling matching and to increase the ultrasound amplitudes. The influences on the imaging of the parameters (such as the angle and height of the water wedge), the array element specifications, and the aperture, were investigated via simulations. The parameter optimization was conducted to establish a suitable detection process. After that, the related probe and a simulated water wedge were designed based on the results and manufactured, in which the simulated wedge as a specific probe holder could adjust its own incident angle and array height. Meanwhile, a typical DN315 pipe of PE 100 was made with some typical artificial defects in it. Experiments were conducted, and the results showed that the proposed water-wedged ultrasonic phased array technique is suitable for butt fusion joint inspection.","PeriodicalId":428760,"journal":{"name":"Volume 6A: Materials and Fabrication","volume":"9 12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121655624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Residual Stress on High Temperature Hydrogen Attack for Pressure Vessels","authors":"Y. Honma, Kunihiko Hashi","doi":"10.1115/pvp2019-94058","DOIUrl":"https://doi.org/10.1115/pvp2019-94058","url":null,"abstract":"\u0000 Nelson curve for carbon steel without post welding heat treatment (PWHT) was reconsidered in Annex F of API PR941 8th Edition because a lot of hydrogen damage cases of carbon steel for pressure vessels and pipes with weld joint were reported. However the mechanism of the damage initiation has not been extensively studied. For these reason, the purpose of this study was to clarify effect of residual stress on high temperature hydrogen attack (HTHA) and examine the mechanism in terms of microstructure.\u0000 The specimens that were simulated welding residual stress by four point bending tool were exposed to high temperature and high pressure hydrogen gas to investigate relationship between damage initiation and condition of temperature and pressure. The frequency of damage occurred by residual stress under high temperature and low hydrogen pressure conditions was higher than that under low temperature and high pressure condition. The damage occurred on boundary of ferrite and pearlite. The grain reference orientation deviation (GROD) map obtained from EBSD measurement indicated the concentration of strain on the boundary generated by plastic deformation. Thus, the damage is most likely initiated by concentration of hydrogen on ferrite-pearlite boundary at which welding strain accumulated. Moreover the damage susceptibility of ferrite-pearlite structure was higher than that of bainite structure. The microstructures in base metal is ferrite-pearlite, but that in heat affected zone is bainite by reheating and cooling at welding. Hence, the base metal has higher damage susceptibility than HAZ.","PeriodicalId":428760,"journal":{"name":"Volume 6A: Materials and Fabrication","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132471632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Damage Evaluation of Grade 91 Thick Cylinder Under Variable Thermal Cyclic Loading Using Continuum Damage Coupled Viscoplastic Models","authors":"Nazrul Islam, T. Hassan","doi":"10.1115/pvp2019-93634","DOIUrl":"https://doi.org/10.1115/pvp2019-93634","url":null,"abstract":"\u0000 This study evaluates creep-fatigue damage in the modified Grade 91 thick-cylinder tested by Japan Atomic Energy Agency (JAEA), to understand the failure mechanism of critical components of Fast Reactor nuclear plants. As modified Grade 91 demonstrated creep-fatigue interaction induced failure mechanisms, finite element analysis of high-temperature components will require a unified constitutive model (UCM) that can simulate various creep-fatigue responses with reasonable accuracy. Hence, a UCM coupled with various advanced modeling features including the continuum damage modeling features is investigated to demonstrate their predictability of the fatigue, creep and creep-fatigue responses of the modified Grade 91 steel. The modified UCM is implemented into ABAQUS for analysis of creep deformation in the thick cylinder benchmark problem. Finite element analysis results are presented to demonstrate how the thermal cycling influences the creep-deformation of this high-temperature component. It is also demonstrated how thermal cycling’s influence on fatigue life can be determined based on the damage variable incorporated in the UCM.","PeriodicalId":428760,"journal":{"name":"Volume 6A: Materials and Fabrication","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132091548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Optimization Design of Storage Efficiency and Structural Analysis for the 3 Cubic Meter Radioactive Waste Container","authors":"Yu-Yu Shen, Hsien-Chou Lin, Hsoung-Wei Chou","doi":"10.1115/pvp2019-93201","DOIUrl":"https://doi.org/10.1115/pvp2019-93201","url":null,"abstract":"\u0000 Because the Taiwan domestic boiling water reactor nuclear power plant is under shutdown and going to be decommissioned, the development of radioactive waste container used for containing the radioactive waste from nuclear facility decommissioning and dismantling is a critical issue in recent years. The main purpose of this study is to design a metal container which can provide the highest storage efficiency for the low level radioactive waste, and ensure the structure meeting the safety requirements of related regulations. This paper first introduces the related regulations for the container in Taiwan. To determine the optimal storage efficiency of the container, the shielding analyses were performed by varying dimensions of 3 cubic meter containers to select the best one, and conduct the structural analyses. Then, a series of structural analyses for operational conditions such as static standstill analysis, lifting test and stacking test with full load were performed, as well as the drop impact analysis, to ensure the container structure meeting the safety requirements of regulations. Present work can provide design information of the development of radioactive waste container for decommissioned nuclear facility in Taiwan.","PeriodicalId":428760,"journal":{"name":"Volume 6A: Materials and Fabrication","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134211762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}