Buried pipelines may be subjected to different seismic hazards along their path, among which faulting can severely affect their integrity by causing large strains in the pipeline confined to a local zone during an earthquake. Historically, the most catastrophic pipeline damages are the ones resulting from oblique faulting due to its severity of ground distortion and induction of compression in the pipeline. Moreover, in the areas of potential ground rupture, the presence of bends near the fault crossing may lead to large strains in the pipeline. Most design guidelines recommend laying the pipelines without field bends, elbows, and flanges. However, bends are sometimes inevitable in the construction of pipelines, and a situation may arise when the pipeline crosses the fault line at/near the bends. Past studies on the response of bent buried pipelines subjected to oblique faulting are very limited. Therefore, the present numerical investigation aims to examine the response of buried continuous steel pipelines with field bends crossing an oblique fault by performing an extensive parametric study. The results obtained are reviewed and presented in the paper. Suitable relationships in terms of modification factors over the response of a straight pipeline as a function of a few critical parameters are determined using regression analyses. It is concluded that providing bends to the pipeline can significantly affect its structural response when subjected to oblique faulting, and especially when it is operating at its design internal pressure.
{"title":"Numerical Study of Horizontally Bent Buried Steel Pipelines Subjected to Oblique Faulting","authors":"Gautam S. Nair, S. Dash, G. Mondal","doi":"10.1115/1.4054686","DOIUrl":"https://doi.org/10.1115/1.4054686","url":null,"abstract":"\u0000 Buried pipelines may be subjected to different seismic hazards along their path, among which faulting can severely affect their integrity by causing large strains in the pipeline confined to a local zone during an earthquake. Historically, the most catastrophic pipeline damages are the ones resulting from oblique faulting due to its severity of ground distortion and induction of compression in the pipeline. Moreover, in the areas of potential ground rupture, the presence of bends near the fault crossing may lead to large strains in the pipeline. Most design guidelines recommend laying the pipelines without field bends, elbows, and flanges. However, bends are sometimes inevitable in the construction of pipelines, and a situation may arise when the pipeline crosses the fault line at/near the bends. Past studies on the response of bent buried pipelines subjected to oblique faulting are very limited. Therefore, the present numerical investigation aims to examine the response of buried continuous steel pipelines with field bends crossing an oblique fault by performing an extensive parametric study. The results obtained are reviewed and presented in the paper. Suitable relationships in terms of modification factors over the response of a straight pipeline as a function of a few critical parameters are determined using regression analyses. It is concluded that providing bends to the pipeline can significantly affect its structural response when subjected to oblique faulting, and especially when it is operating at its design internal pressure.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63503635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Allowable stresses for pipes with circumferential flaws are provided by the ASME Code Section XI. The stresses are determined by fully plastic collapse stresses and safety factors. The plastic collapse stresses are estimated by Limit Load Criteria, which are also provided by the ASME Code Section XI. When applied stresses of the pipes at the flaw locations are less than the allowable stresses, the flaws are acceptable for the end-of-evaluation period. The allowable stresses are categorized for various service level conditions of the plant operation. When pipe walls are thin, part-through flaws can easily develop into through-wall flaws, and the likelihood of coolant leakage is high. The ASME Code Section XI provides final allowable flaw angles of through-wall flaws for thin-walled pipes. The final allowable angles are currently applied to pipes in order to maintain structural tolerance if the part-through flaws become through-wall flaws. To ensure that this stability is not compromised, plastic collapse stresses for through-wall flaws are combined with the allowable stresses. However, the final allowable angles of through-wall flaws are not identified for thin-walled pipes. This paper compares plastic collapse stresses of through-wall flaws and allowable stresses of part-through flaws for pipes. The comparison of these stresses is used to derive the final allowable angles of through-wall flaws. The angles can be expressed either in the form of exact solutions or as conventional options that are appropriate for various service level conditions.
{"title":"Stability of Allowable Flaw Angles for High Toughness Ductile Pipes Subjected to Bending Stress in the ASME Code Section XI","authors":"K. Hasegawa, B. Strnadel, Yinsheng Li, V. Lacroix","doi":"10.1115/1.4054620","DOIUrl":"https://doi.org/10.1115/1.4054620","url":null,"abstract":"\u0000 Allowable stresses for pipes with circumferential flaws are provided by the ASME Code Section XI. The stresses are determined by fully plastic collapse stresses and safety factors. The plastic collapse stresses are estimated by Limit Load Criteria, which are also provided by the ASME Code Section XI. When applied stresses of the pipes at the flaw locations are less than the allowable stresses, the flaws are acceptable for the end-of-evaluation period. The allowable stresses are categorized for various service level conditions of the plant operation.\u0000 When pipe walls are thin, part-through flaws can easily develop into through-wall flaws, and the likelihood of coolant leakage is high. The ASME Code Section XI provides final allowable flaw angles of through-wall flaws for thin-walled pipes. The final allowable angles are currently applied to pipes in order to maintain structural tolerance if the part-through flaws become through-wall flaws. To ensure that this stability is not compromised, plastic collapse stresses for through-wall flaws are combined with the allowable stresses. However, the final allowable angles of through-wall flaws are not identified for thin-walled pipes.\u0000 This paper compares plastic collapse stresses of through-wall flaws and allowable stresses of part-through flaws for pipes. The comparison of these stresses is used to derive the final allowable angles of through-wall flaws. The angles can be expressed either in the form of exact solutions or as conventional options that are appropriate for various service level conditions.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48153880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wound tube, which is an important component of Coil-wound heat exchanger (CWHE), is subjected to cross-flow impacting and thereby vibrating. Owing to investigate Flow-induced vibration (FIV) of wound tubes, it is essential to study the vibration characteristics of the tubes. In this paper, the natural vibration characteristics of wound tube, which was divided into curved tube and coil tube based on support conditions, were studied in detail. And experiments, numerical simulations and calculation methods were carried out. First, the structures of the two tubes were described parametrically. Afterwards, vibration experiments proved the reliability of numerical simulations of the tubes. Furthermore, calculation methods for the fundamental frequencies of the two tubes were proposed, the accuracies of which were further proven by comparison with simulation results. In addition, the first three mode shapes of the curved tube and coil tube were bending vibration modes. Then the influence of structural parameters on the fundamental frequency was discussed and the independence of parameters was demonstrated. The effects of the variables of the layer pitch ratio, a, the same layer pitch ratio, b, and helix angle, a, on the added mass coefficient, Cm, were ultimately investigated. In general, this paper provides a technical basis to evaluate the design and machining for design and supervision staff.
{"title":"Investigation in the Natural Frequency of Wound Tube for Coil-Wound Heat Exchanger","authors":"Yue Wang, Peng Ren, Guofeng Huang, W. Tan","doi":"10.1115/1.4054621","DOIUrl":"https://doi.org/10.1115/1.4054621","url":null,"abstract":"\u0000 Wound tube, which is an important component of Coil-wound heat exchanger (CWHE), is subjected to cross-flow impacting and thereby vibrating. Owing to investigate Flow-induced vibration (FIV) of wound tubes, it is essential to study the vibration characteristics of the tubes. In this paper, the natural vibration characteristics of wound tube, which was divided into curved tube and coil tube based on support conditions, were studied in detail. And experiments, numerical simulations and calculation methods were carried out. First, the structures of the two tubes were described parametrically. Afterwards, vibration experiments proved the reliability of numerical simulations of the tubes. Furthermore, calculation methods for the fundamental frequencies of the two tubes were proposed, the accuracies of which were further proven by comparison with simulation results. In addition, the first three mode shapes of the curved tube and coil tube were bending vibration modes. Then the influence of structural parameters on the fundamental frequency was discussed and the independence of parameters was demonstrated. The effects of the variables of the layer pitch ratio, a, the same layer pitch ratio, b, and helix angle, a, on the added mass coefficient, Cm, were ultimately investigated. In general, this paper provides a technical basis to evaluate the design and machining for design and supervision staff.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46282554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Markian P. Petkov, G. Young, Pierre-Alexandre Juan
Future Gen IV high-temperature reactors are expected to operate above 450C where creep effects are significant in safety-related structures, e.g., reactor vessels. ASME BPVC Section III Division 5 provides the rules and methodologies for design of such high-temperature components. Of relevance to the Designer are the isochronous stress-strain curves (ISSCs) part of the rules for deformation limits in the Code. The ISSCs are an important method to estimate accumulated inelastic strains at a given stress and duration at elevated temperatures. In this study, the ISSCs for 316H steel in the current edition of ASME BPVC Section III Division 5 have been re-evaluated between 593-750C by adopting a physics-informed minimum creep rate model to re-construct them. It is demonstrated that the current ASME Section III Division 5 minimum creep rate model underpredicts creep rates compared to experimental data at low stresses (e.g., 650C, 40 MPa). By employing a physics-informed minimum creep rate model capturing both diffusive- and dislocation glide/climb-controlled creep regimes, this deficiency is addressed. The ASME ISSCs for 316H stainless steel are then reconstructed by adopting this modified minimum creep rate model. It was found that the ASME ISSCs could underestimate total accumulated strains at ~S/Sy of 0.65 for durations of 1,000 hr by 10 times which could give rise to non-conservatism in inelastic strain. Experimental data at various temperatures confirm the findings. Potential approaches to address this non-conservatism are discussed.
{"title":"Non-Conservatism of ASME BPVC Section III Division 5 Isochronous Stress-Strain Curves for 316H Stainless Steel at Low Stresses","authors":"Markian P. Petkov, G. Young, Pierre-Alexandre Juan","doi":"10.1115/1.4054622","DOIUrl":"https://doi.org/10.1115/1.4054622","url":null,"abstract":"\u0000 Future Gen IV high-temperature reactors are expected to operate above 450C where creep effects are significant in safety-related structures, e.g., reactor vessels. ASME BPVC Section III Division 5 provides the rules and methodologies for design of such high-temperature components. Of relevance to the Designer are the isochronous stress-strain curves (ISSCs) part of the rules for deformation limits in the Code. The ISSCs are an important method to estimate accumulated inelastic strains at a given stress and duration at elevated temperatures. In this study, the ISSCs for 316H steel in the current edition of ASME BPVC Section III Division 5 have been re-evaluated between 593-750C by adopting a physics-informed minimum creep rate model to re-construct them. It is demonstrated that the current ASME Section III Division 5 minimum creep rate model underpredicts creep rates compared to experimental data at low stresses (e.g., 650C, 40 MPa). By employing a physics-informed minimum creep rate model capturing both diffusive- and dislocation glide/climb-controlled creep regimes, this deficiency is addressed. The ASME ISSCs for 316H stainless steel are then reconstructed by adopting this modified minimum creep rate model. It was found that the ASME ISSCs could underestimate total accumulated strains at ~S/Sy of 0.65 for durations of 1,000 hr by 10 times which could give rise to non-conservatism in inelastic strain. Experimental data at various temperatures confirm the findings. Potential approaches to address this non-conservatism are discussed.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42717013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The stainless steel lined clad pipe (SSLCP) can be widely used in different fields. Industrial SSLCP are generally manufactured by the cold hydraulic expansion (CHE) method which requires high hydraulic pressure and good sealing property. The inter-layer bonding force is difficult to obtain by the CHE when there is little difference between the yield strengths of inner and outer pipes. Furthermore, the hydraulic expansion process nearly can not be achieved when the yield strength of inner pipe is higher than that of outer pipe. The thermal hydraulic expansion (THE) method can overcome these difficulties. In this paper, the graph method was adopted to analyze the THE principles for "inner strong and outer weak (ISOW)" and "outer strong and inner weak (OSIW)" pipes. The effective hydraulic expansion criterion conditions of SSLCPs were proposed and can be used as basis of clad pipe material matching and forming process selection. Through the stress and strain analysis of inner and outer pipes during THE process, the deformation coordination conditions of elastic deformation and thermal deformation of the inner and outer pipe were established. The correlation between the residual contact pressure p*c, the hydraulic expansion pressure pi and the effective temperature difference ?Te were derived. The calculation formula of the maximum expansion pressure pimax and the minimum expansion pressure pimin was obtained. The maximum heating temperature of outer pipe was also derived. Furthermore, the finite element analysis (FEA) method was adopted and simulated results verify the feasibility and applicability of the theory study.
{"title":"Theoretical Study On Thermal Hydraulic Expansion Process of Stainless Steel Lined Clad Pipe","authors":"Yanbin Liu, Xuesheng Wang, Junjiang Yu, Xinya Qin, Jiameng Zheng, Guoxun Sang","doi":"10.1115/1.4054545","DOIUrl":"https://doi.org/10.1115/1.4054545","url":null,"abstract":"\u0000 The stainless steel lined clad pipe (SSLCP) can be widely used in different fields. Industrial SSLCP are generally manufactured by the cold hydraulic expansion (CHE) method which requires high hydraulic pressure and good sealing property. The inter-layer bonding force is difficult to obtain by the CHE when there is little difference between the yield strengths of inner and outer pipes. Furthermore, the hydraulic expansion process nearly can not be achieved when the yield strength of inner pipe is higher than that of outer pipe. The thermal hydraulic expansion (THE) method can overcome these difficulties. In this paper, the graph method was adopted to analyze the THE principles for \"inner strong and outer weak (ISOW)\" and \"outer strong and inner weak (OSIW)\" pipes. The effective hydraulic expansion criterion conditions of SSLCPs were proposed and can be used as basis of clad pipe material matching and forming process selection. Through the stress and strain analysis of inner and outer pipes during THE process, the deformation coordination conditions of elastic deformation and thermal deformation of the inner and outer pipe were established. The correlation between the residual contact pressure p*c, the hydraulic expansion pressure pi and the effective temperature difference ?Te were derived. The calculation formula of the maximum expansion pressure pimax and the minimum expansion pressure pimin was obtained. The maximum heating temperature of outer pipe was also derived. Furthermore, the finite element analysis (FEA) method was adopted and simulated results verify the feasibility and applicability of the theory study.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43571703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ferritic steels, which are typically used for critical reactor components, including reactor pressure vessels (RPV), exhibit a temperature-dependent probability of cleavage fracture, termed ductile-to-brittle transition. The fracture process has been linked to the interaction between matrix plasticity and second-phase particles. Under high-enough loads, a competition exists between cleavage and ductile fracture, which results from particles rupturing to form microcracks or particles decohering to form microvoids, respectively. Currently, there is no sufficiently adequate model that can predict accurately the reduced probability of cleavage with increasing temperature and the associated increase of plastic deformation. In this work, failure probability has been estimated using a local approach to cleavage fracture incorporating the statistics of microcracks. It is shown that changes in the deformation material properties are not enough to capture the significant changes in fracture toughness. Instead, a correction to the fraction of particles converted to eligible for cleavage microcracks, with an exponential dependence on the plastic strains, is proposed. The proposed method is compared with previous corrections that incorporate the plastic strains, and its advantages are demonstrated. The method is developed for the RPV steel 22NiMoCr37 and using experimental data for a standard compact tension C(T) specimen. The proposed approach offers more accurate calculations of cleavage fracture toughness in the ductile-to-brittle transition regime using only a decoupled model, which is attractive for engineering practice.
{"title":"Capturing the Temperature Dependence of Cleavage Fracture Toughness in the Ductile-to-Brittle Transition Regime in Ferritic Steels Using an Improved Engineering Local Approach","authors":"M. Yankova, A. Jivkov, R. Patel, A. Sherry","doi":"10.1115/1.4054497","DOIUrl":"https://doi.org/10.1115/1.4054497","url":null,"abstract":"\u0000 Ferritic steels, which are typically used for critical reactor components, including reactor pressure vessels (RPV), exhibit a temperature-dependent probability of cleavage fracture, termed ductile-to-brittle transition. The fracture process has been linked to the interaction between matrix plasticity and second-phase particles. Under high-enough loads, a competition exists between cleavage and ductile fracture, which results from particles rupturing to form microcracks or particles decohering to form microvoids, respectively. Currently, there is no sufficiently adequate model that can predict accurately the reduced probability of cleavage with increasing temperature and the associated increase of plastic deformation. In this work, failure probability has been estimated using a local approach to cleavage fracture incorporating the statistics of microcracks. It is shown that changes in the deformation material properties are not enough to capture the significant changes in fracture toughness. Instead, a correction to the fraction of particles converted to eligible for cleavage microcracks, with an exponential dependence on the plastic strains, is proposed. The proposed method is compared with previous corrections that incorporate the plastic strains, and its advantages are demonstrated. The method is developed for the RPV steel 22NiMoCr37 and using experimental data for a standard compact tension C(T) specimen. The proposed approach offers more accurate calculations of cleavage fracture toughness in the ductile-to-brittle transition regime using only a decoupled model, which is attractive for engineering practice.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42326671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A whole-body 1.5T superconducting MRI magnet is operated in 4.2K inside a zero-boil-off helium cryogenic vessel i.e. cryostat. The cryostat has horizontal bore of 850 mm used as the patient bore. The cryostat houses the 1.5T superconducting magnet in a coaxial position maintaining a high degree of alignment along with the gradient coil, the birdcage RF coil necessary for any MRI scanner. A set of support link having low thermal conductivity and higher mechanical strength would provide structural support to the cold mass at 4.2K which includes the superconducting magnet, helium vessel. A two stage 4.2K G-M cryocooler is used to recondense helium to achieve a 'zero boil-off' condition. The helium vessel and the vacuum vessel of the cryostat experience stresses during the normal operation, transportation etc. The ASME B&PV Code and the Finite Element Analysis has been used for the engineering design and stress analysis of cryostat. The modal analysis of the cryostat has been done during the transportation of the cryostat. The seismic behaviour of the cryostat has also been analyzed extensively for a 1.5T MRI cryostat
{"title":"Mechanical Stress Analysis of Zero-Boil-Off Cryostat for a 1.5 T MRI magnet","authors":"N. Suman, A. N. Siddiquee, Sujita Kumar Kar","doi":"10.1115/1.4054496","DOIUrl":"https://doi.org/10.1115/1.4054496","url":null,"abstract":"\u0000 A whole-body 1.5T superconducting MRI magnet is operated in 4.2K inside a zero-boil-off helium cryogenic vessel i.e. cryostat. The cryostat has horizontal bore of 850 mm used as the patient bore. The cryostat houses the 1.5T superconducting magnet in a coaxial position maintaining a high degree of alignment along with the gradient coil, the birdcage RF coil necessary for any MRI scanner. A set of support link having low thermal conductivity and higher mechanical strength would provide structural support to the cold mass at 4.2K which includes the superconducting magnet, helium vessel. A two stage 4.2K G-M cryocooler is used to recondense helium to achieve a 'zero boil-off' condition. The helium vessel and the vacuum vessel of the cryostat experience stresses during the normal operation, transportation etc. The ASME B&PV Code and the Finite Element Analysis has been used for the engineering design and stress analysis of cryostat. The modal analysis of the cryostat has been done during the transportation of the cryostat. The seismic behaviour of the cryostat has also been analyzed extensively for a 1.5T MRI cryostat","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41725034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article investigates the influences of different material distribution types and flow profiles in the cross-section on dynamics of cantilevered axially functionally graded (AFG) pipe. Functionally graded material as a designable material, its appliance in structures can enhance the stability of the structure by adequately choosing the material constituents and arranging constituents' distribution. The governing equation of the pipe system is derived based on the Euler-Bernoulli beam theory and numerically solved by the differential quadrature method (DQM). The influences of different volume fraction function and non-uniform flow velocity distribution on the natural frequencies and average critical flow velocities are discussed according to the numerical results. It can be concluded that the enhanced effect of the AFG material is mainly caused by increment in the amount of stiffer constituent. With the same amount, pure distribution difference in exponential or power function type that brings stiffer fixed end results in slightly higher critical velocity against flutter. Ignoring the non-uniform flow velocity distribution leads to an overestimation of the pipe's stability and the overestimation is even apparent on AFG pipe. Non-uniform velocity distribution affects the stable flow velocity area and appearance of restabilizing phenomena.
{"title":"The Effects of Material Distribution and Flow Profile On the Stability of Cantilevered Axially Functionally Graded Pipes","authors":"Jiayin Dai, Yong-shou Liu, Guo-jun Tong, Zhenyi Yuan","doi":"10.1115/1.4054450","DOIUrl":"https://doi.org/10.1115/1.4054450","url":null,"abstract":"\u0000 This article investigates the influences of different material distribution types and flow profiles in the cross-section on dynamics of cantilevered axially functionally graded (AFG) pipe. Functionally graded material as a designable material, its appliance in structures can enhance the stability of the structure by adequately choosing the material constituents and arranging constituents' distribution. The governing equation of the pipe system is derived based on the Euler-Bernoulli beam theory and numerically solved by the differential quadrature method (DQM). The influences of different volume fraction function and non-uniform flow velocity distribution on the natural frequencies and average critical flow velocities are discussed according to the numerical results. It can be concluded that the enhanced effect of the AFG material is mainly caused by increment in the amount of stiffer constituent. With the same amount, pure distribution difference in exponential or power function type that brings stiffer fixed end results in slightly higher critical velocity against flutter. Ignoring the non-uniform flow velocity distribution leads to an overestimation of the pipe's stability and the overestimation is even apparent on AFG pipe. Non-uniform velocity distribution affects the stable flow velocity area and appearance of restabilizing phenomena.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41768892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ASME Boiler and Pressure Vessel Code Section XI prescribes the stress intensity factor solutions at the surface and deepest point for a semi-elliptical crack. The ASME Code Section XI, however, provides no solutions for a crack with a large aspect ratio, that is a crack in which the crack depth a is larger than the half-length c. The difficulty in treating the crack with large aspect ratio relates to the position of the maximum stress intensity factor, which appears at neither the surface point nor the deepest point. In this paper we investigate the influence of the stress intensity factor at the maximum point for a circumferential crack and an axial crack with a large aspect ratio in a cylinder. First, we obtained the influence coefficients Gi for the stress intensity factor at the surface point, the deepest point, and the maximum point by finite element analysis, and developed a series of closed-form Gi solutions. Three geometrical factors are considered as parameters affecting the influence coefficients Gi: aspect ratio (a/l = 0.5, 1.0, 2.0, and 4.0), crack depth ratio (a/t = 0.01, 0.1, 0.2, 0.2, 0.4, 0.6 and 0.8), and radius to thickness ratio (Ri/t = 2, 5, 10, 20, 40, and 80). Finally, we proposed methods for evaluating the stress intensity factor for a crack with a large aspect ratio in a manner that characterizes the influence of the solutions at the maximum point.
{"title":"Closed-Form Stress Intensity Factor Solutions for Circumferential and Axial Surface Cracks with Large Aspect Ratios in Pipes","authors":"Kisaburo Azuma, Yinsheng Li","doi":"10.1115/1.4054365","DOIUrl":"https://doi.org/10.1115/1.4054365","url":null,"abstract":"\u0000 The ASME Boiler and Pressure Vessel Code Section XI prescribes the stress intensity factor solutions at the surface and deepest point for a semi-elliptical crack. The ASME Code Section XI, however, provides no solutions for a crack with a large aspect ratio, that is a crack in which the crack depth a is larger than the half-length c. The difficulty in treating the crack with large aspect ratio relates to the position of the maximum stress intensity factor, which appears at neither the surface point nor the deepest point.\u0000 In this paper we investigate the influence of the stress intensity factor at the maximum point for a circumferential crack and an axial crack with a large aspect ratio in a cylinder. First, we obtained the influence coefficients Gi for the stress intensity factor at the surface point, the deepest point, and the maximum point by finite element analysis, and developed a series of closed-form Gi solutions. Three geometrical factors are considered as parameters affecting the influence coefficients Gi: aspect ratio (a/l = 0.5, 1.0, 2.0, and 4.0), crack depth ratio (a/t = 0.01, 0.1, 0.2, 0.2, 0.4, 0.6 and 0.8), and radius to thickness ratio (Ri/t = 2, 5, 10, 20, 40, and 80). Finally, we proposed methods for evaluating the stress intensity factor for a crack with a large aspect ratio in a manner that characterizes the influence of the solutions at the maximum point.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42085560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The liner of type 3 high-pressure vessel is manufactured by a D.D.I.(Deep drawing and ironing) process for the cylinder part, which is a continuous process that includes a drawing process to reduce the diameter of the billet and a subsequent ironing process to reduce the thickness of the billet. But the wall thickness of type 3 pressure vessel liners used in vehicles and ships is required to be 5mm. Excessive wall thickness not only increases the weight of hydrogen vehicles and ships equipped with type 3 high-pressure vessels but also deteriorates their transportation efficiency. But the forming process of the cylinder part of the high-pressure vessel liner(Al6061) has a total of 3 stages (1st deep drawing with blank holder, 2nd redrawing, 3rd redrawing + ironing) through which the wall thickness is manufactured up to 6.8mm in the actual field. In this study, the maximum drawing ratio and die inflow angle in the first-stage deep drawing process by using the shape factor formula of the tractrix die and combined process (redrawing + ironing) in the third stage were determined in order to manufacture a liner with a wall thickness of 5 mm within the existing 3 stages, including saving of die costs. Using damage value verified through FEA and experiment and based on the above results, design of the D.D.I. process (3 stages) was performed, and its results were verified.
{"title":"Design of Type 3 High-Pressure Vessel Liner(Al 6061) for Hydrogen Vehicles","authors":"C. Lee, G. Park, Chul Kim","doi":"10.1115/1.4054366","DOIUrl":"https://doi.org/10.1115/1.4054366","url":null,"abstract":"\u0000 The liner of type 3 high-pressure vessel is manufactured by a D.D.I.(Deep drawing and ironing) process for the cylinder part, which is a continuous process that includes a drawing process to reduce the diameter of the billet and a subsequent ironing process to reduce the thickness of the billet. But the wall thickness of type 3 pressure vessel liners used in vehicles and ships is required to be 5mm. Excessive wall thickness not only increases the weight of hydrogen vehicles and ships equipped with type 3 high-pressure vessels but also deteriorates their transportation efficiency. But the forming process of the cylinder part of the high-pressure vessel liner(Al6061) has a total of 3 stages (1st deep drawing with blank holder, 2nd redrawing, 3rd redrawing + ironing) through which the wall thickness is manufactured up to 6.8mm in the actual field. In this study, the maximum drawing ratio and die inflow angle in the first-stage deep drawing process by using the shape factor formula of the tractrix die and combined process (redrawing + ironing) in the third stage were determined in order to manufacture a liner with a wall thickness of 5 mm within the existing 3 stages, including saving of die costs. Using damage value verified through FEA and experiment and based on the above results, design of the D.D.I. process (3 stages) was performed, and its results were verified.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46395843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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