In CANDU nuclear reactors, pressure tubes reside within a calandria tube with separation maintained by helical springs installed in the annular space. Evaluation of material degradation due to the unique operating environment requires testing of ex-service spring material by compressing short spring segments by two diametrically opposed forces. The load vs. displacement results combined with the geometry allows for the stress-strain behavior to be derived. The test specimens are effectively unmodified from the as-received condition so accurate characterization of the geometry is required. Since the test response is mainly bending, error in the radial section dimension is augmented by powers of 2 and 3 when calculating bending stress and specimen stiffness respectively. Additional complications come from nonuniform loading of the coils due to end effects. Detailed analysis that accounts for end effects is applied to the linear elastic portion of the load curve to accurately quantify the specimen dimensions. With geometry determined, the nonlinear portion of the tensile curve is adjusted to reproduce the entire load curve up to the failure point. Examples are presented to demonstrate how the load corresponding to the yield point and outer fiber stress at the failure point can be determined.
{"title":"Analysis to Relate Data From Radial Compression Tests on Helical Springs to Tensile Material Properties","authors":"André Gagnon, D. Metzger","doi":"10.1115/pvp2022-84892","DOIUrl":"https://doi.org/10.1115/pvp2022-84892","url":null,"abstract":"\u0000 In CANDU nuclear reactors, pressure tubes reside within a calandria tube with separation maintained by helical springs installed in the annular space. Evaluation of material degradation due to the unique operating environment requires testing of ex-service spring material by compressing short spring segments by two diametrically opposed forces. The load vs. displacement results combined with the geometry allows for the stress-strain behavior to be derived. The test specimens are effectively unmodified from the as-received condition so accurate characterization of the geometry is required. Since the test response is mainly bending, error in the radial section dimension is augmented by powers of 2 and 3 when calculating bending stress and specimen stiffness respectively. Additional complications come from nonuniform loading of the coils due to end effects.\u0000 Detailed analysis that accounts for end effects is applied to the linear elastic portion of the load curve to accurately quantify the specimen dimensions. With geometry determined, the nonlinear portion of the tensile curve is adjusted to reproduce the entire load curve up to the failure point. Examples are presented to demonstrate how the load corresponding to the yield point and outer fiber stress at the failure point can be determined.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"205 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88576209","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}
If the water piping system under high temperature and pressure is damaged and water is ejected into the atmosphere, a jet with depressurization boiling (Flashing) may occur. Therefore, it is necessary to evaluate the range of the jet impact on surrounding equipment and people. The range of the jet impact is evaluated by the existing code adopted in Japan (JSME S ND1) which referred to the standards adopted in America (ANSI/ANS-58.2-1988). The problem with this standard is that the experimental validity of the range of the jet impact has not been confirmed in Japan. In this study, we investigated experimentally to confirm the validity of the expanding angle and the affected area of the flashing jet of saturated water under low-pressure conditions, and further investigated the high-pressure conditions, which are difficult in the experiment, using Computational Fluid Dynamics (CFD).
如果高温高压下的水管系统被损坏，水被喷射到大气中，可能会出现减压沸腾(闪蒸)的射流。因此，有必要评估射流对周围设备和人员的影响范围。喷气机撞击的范围是根据日本采用的现行规范(JSME S ND1)进行评估的，该规范参考了美国采用的标准(ANSI/ANS-58.2-1988)。这一标准的问题在于，喷气机撞击范围的实验有效性在日本尚未得到证实。本研究通过实验验证了低压条件下饱和水闪蒸射流扩展角和影响面积的有效性，并利用计算流体力学(CFD)对实验难点高压条件进行了进一步研究。
{"title":"Evaluation of Flashing Jet Impact on Surroundings Due to Leakage of High Pressure Pipes","authors":"T. Yuasa, Shun Watanabe, R. Morita","doi":"10.1115/pvp2022-80253","DOIUrl":"https://doi.org/10.1115/pvp2022-80253","url":null,"abstract":"\u0000 If the water piping system under high temperature and pressure is damaged and water is ejected into the atmosphere, a jet with depressurization boiling (Flashing) may occur. Therefore, it is necessary to evaluate the range of the jet impact on surrounding equipment and people. The range of the jet impact is evaluated by the existing code adopted in Japan (JSME S ND1) which referred to the standards adopted in America (ANSI/ANS-58.2-1988). The problem with this standard is that the experimental validity of the range of the jet impact has not been confirmed in Japan. In this study, we investigated experimentally to confirm the validity of the expanding angle and the affected area of the flashing jet of saturated water under low-pressure conditions, and further investigated the high-pressure conditions, which are difficult in the experiment, using Computational Fluid Dynamics (CFD).","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79832892","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}
The Spallation Neutron Source (SNS) accelerator is being upgraded to increase the beam power from 1.4MW at 1GeV to 2.8MW at 1.3GeV. The currents in the middle two injection chicane magnets cannot simply be scaled up to accommodate the increased injection energy of 1.3GeV due to potential excessive H− stripping; the magnets must be replaced with longer, lower-field magnets and the associated vacuum chambers need to be redesigned. A new teardrop-shaped vacuum chamber was initially designed to accommodate the new magnets and the updated beam paths and instrumentation. This paper focuses on the structural stability study of the teardrop shape vacuum chamber based on buckling analysis. Protection against collapse from buckling according to the ASME BPVC requirement has been evaluated in depth. First, a Type-1 bifurcation buckling analysis using a linear eigenvalue solution to determine the critical load factor was performed. Subsequently, a Type-3 nonlinear collapse analysis was conducted using the static Riks method with elastic-plastic material properties and imperfections explicitly considered in the model geometry. The critical buckling load for the teardrop shape vacuum chamber was confidently estimated based upon this two-stage approach.
{"title":"Bifurcation Buckling Analysis and Non-Linear Collapse Analysis of Teardrop Shaped Vacuum Chamber","authors":"Hao Jiang, C. Barbier, B. Riemer","doi":"10.1115/pvp2022-82187","DOIUrl":"https://doi.org/10.1115/pvp2022-82187","url":null,"abstract":"\u0000 The Spallation Neutron Source (SNS) accelerator is being upgraded to increase the beam power from 1.4MW at 1GeV to 2.8MW at 1.3GeV. The currents in the middle two injection chicane magnets cannot simply be scaled up to accommodate the increased injection energy of 1.3GeV due to potential excessive H− stripping; the magnets must be replaced with longer, lower-field magnets and the associated vacuum chambers need to be redesigned. A new teardrop-shaped vacuum chamber was initially designed to accommodate the new magnets and the updated beam paths and instrumentation. This paper focuses on the structural stability study of the teardrop shape vacuum chamber based on buckling analysis. Protection against collapse from buckling according to the ASME BPVC requirement has been evaluated in depth. First, a Type-1 bifurcation buckling analysis using a linear eigenvalue solution to determine the critical load factor was performed. Subsequently, a Type-3 nonlinear collapse analysis was conducted using the static Riks method with elastic-plastic material properties and imperfections explicitly considered in the model geometry. The critical buckling load for the teardrop shape vacuum chamber was confidently estimated based upon this two-stage approach.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"08 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78163857","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}
The Reactor Inner Zone Inlet Header (RIZIH) temperatures have raised more rapidly in the CANDU units in general, compared to the original aging predictions. This adverse trend is caused by a degradation mechanism that affecting heat exchange efficiency in certain areas of the process systems. The main contributor to the RIZIH temperature increase is the fouling in the preheaters and steam generator/boilers due to magnetite deposits on tube internal diameters. The RIZIH temperature rise had caused units de-rates to ensure the reactor safety and comply with the regulatory requirements. As reported in a previous PVP paper (PVP2017-65096), multiple design alternatives were considered and evaluated to address the adverse condition, the best design option with a piping modification by adding external feedwater bypass of high pressure heater was selected to improve RIZIH temperature control. Following the conceptual engineering, preliminary design and detail design, the engineering change was implemented in two CANDU reactor units between 2018 and 2019. This paper reports out the field physical implementations and discusses the effectiveness of the design change on mitigating the RIZIH temperature rise, it also presents the operational and financial benefits actualized through observations of the two implementing units.
{"title":"Design Modification Implementations for Mitigating the Reactor Inner Zone Inlet Header Temperature in CANDU Reactor Units","authors":"Preston Tang, Bing Li, Akash Bhatia, Leon Cramer","doi":"10.1115/pvp2022-85985","DOIUrl":"https://doi.org/10.1115/pvp2022-85985","url":null,"abstract":"\u0000 The Reactor Inner Zone Inlet Header (RIZIH) temperatures have raised more rapidly in the CANDU units in general, compared to the original aging predictions. This adverse trend is caused by a degradation mechanism that affecting heat exchange efficiency in certain areas of the process systems. The main contributor to the RIZIH temperature increase is the fouling in the preheaters and steam generator/boilers due to magnetite deposits on tube internal diameters. The RIZIH temperature rise had caused units de-rates to ensure the reactor safety and comply with the regulatory requirements. As reported in a previous PVP paper (PVP2017-65096), multiple design alternatives were considered and evaluated to address the adverse condition, the best design option with a piping modification by adding external feedwater bypass of high pressure heater was selected to improve RIZIH temperature control. Following the conceptual engineering, preliminary design and detail design, the engineering change was implemented in two CANDU reactor units between 2018 and 2019. This paper reports out the field physical implementations and discusses the effectiveness of the design change on mitigating the RIZIH temperature rise, it also presents the operational and financial benefits actualized through observations of the two implementing units.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"52 7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73486010","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}
The ASME BPVC, Section III, Appendix XI [1] regulates the flange calculation for class 2 and 3 components in Suisse nuclear power plants, and it is also used for class 1 flanges. The most common European Standard for the design of bolted flanged joints is EN 1591-1 [2], the required gasket characteristics for this calculation procedure are defined in EN 13555 [3]. These characteristics can be determined experimentally and they are not only used in EN 1591-1 but also in more realistic finite-element calculations. Finite element calculations are carried out for a certain number of combinations of flange and gasket materials as well as bolt types in order to prove compliance with the integrity and tightness of the connections in the assembly and subsequent operational states, taking into account the tightening torques. A total of almost 400 different combinations of flange, bolt and gasket geometries and materials were examined. The focus is laid on flange types fabricated according to European standards which are generally thinner — looking at the wall thickness or flange ring in the same pressure range — than in the ASME world. In this paper the bolting-up torque moments determined with the European standard EN 1591-1 for the flange connections, are assessed with twice elastic slope method, limit load and elastic-plastic stress analysis according to ASME BPVC, Section VIII, Div. 2. [4] Proof of acceptability of the nonlinear finite element-calculations are conducted according to ASME standard procedures like ASME SECTION III, Appendices EE and FF for the level D.
{"title":"Comparison Between Different Calculation Methods for Determining Bolting-Up Torque Moments","authors":"Alexander Mutz, M. Schaaf, S. Hufnagel","doi":"10.1115/pvp2022-86163","DOIUrl":"https://doi.org/10.1115/pvp2022-86163","url":null,"abstract":"\u0000 The ASME BPVC, Section III, Appendix XI [1] regulates the flange calculation for class 2 and 3 components in Suisse nuclear power plants, and it is also used for class 1 flanges.\u0000 The most common European Standard for the design of bolted flanged joints is EN 1591-1 [2], the required gasket characteristics for this calculation procedure are defined in EN 13555 [3]. These characteristics can be determined experimentally and they are not only used in EN 1591-1 but also in more realistic finite-element calculations.\u0000 Finite element calculations are carried out for a certain number of combinations of flange and gasket materials as well as bolt types in order to prove compliance with the integrity and tightness of the connections in the assembly and subsequent operational states, taking into account the tightening torques. A total of almost 400 different combinations of flange, bolt and gasket geometries and materials were examined. The focus is laid on flange types fabricated according to European standards which are generally thinner — looking at the wall thickness or flange ring in the same pressure range — than in the ASME world.\u0000 In this paper the bolting-up torque moments determined with the European standard EN 1591-1 for the flange connections, are assessed with twice elastic slope method, limit load and elastic-plastic stress analysis according to ASME BPVC, Section VIII, Div. 2. [4] Proof of acceptability of the nonlinear finite element-calculations are conducted according to ASME standard procedures like ASME SECTION III, Appendices EE and FF for the level D.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"134 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83419503","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}
Low-stress spiral wound gaskets are marketed as an alternative to standard spiral wound gaskets, requiring less torque to seat the gasket. Spiral wound gaskets are common commodities used in piping reliability staff are constantly looking for different alternatives. Multiple manufacturers offer a low-stress version of spiral wound gaskets. Do these spiral wound gaskets offer a low-stress solution, and do they perform better than a standard spiral wound gasket? This paper will go beyond the marketing of “low-stress” spiral wound gaskets and examine the construction and engineering behind these gasket designs. Manufacturers of spiral wound gaskets have made subtle changes and the “low-stress” technology has become a common theme throughout the spiral wound gasket market. Multiple chemical and petrochemical plants use these designs in their piping systems and sometimes as replacements for ASME recommended spiral wound gaskets with inner rings. Low-stress spiral wound gaskets have multiple designs from additional graphite in the filler to an anti-buckling design which are marketed as requiring less initial preload to seat. This paper will examine the validity of these gaskets and determine if they are low-stress and if they provide a credible seal in a bolted flanged joint. [1]
{"title":"A Critical Understanding of “Low-Stress” Spiral Wound Gaskets","authors":"Alton Jamison","doi":"10.1115/pvp2022-84739","DOIUrl":"https://doi.org/10.1115/pvp2022-84739","url":null,"abstract":"\u0000 Low-stress spiral wound gaskets are marketed as an alternative to standard spiral wound gaskets, requiring less torque to seat the gasket. Spiral wound gaskets are common commodities used in piping reliability staff are constantly looking for different alternatives. Multiple manufacturers offer a low-stress version of spiral wound gaskets. Do these spiral wound gaskets offer a low-stress solution, and do they perform better than a standard spiral wound gasket? This paper will go beyond the marketing of “low-stress” spiral wound gaskets and examine the construction and engineering behind these gasket designs. Manufacturers of spiral wound gaskets have made subtle changes and the “low-stress” technology has become a common theme throughout the spiral wound gasket market. Multiple chemical and petrochemical plants use these designs in their piping systems and sometimes as replacements for ASME recommended spiral wound gaskets with inner rings. Low-stress spiral wound gaskets have multiple designs from additional graphite in the filler to an anti-buckling design which are marketed as requiring less initial preload to seat. This paper will examine the validity of these gaskets and determine if they are low-stress and if they provide a credible seal in a bolted flanged joint. [1]","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"125 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83437273","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}
Finite element analysis (FEA) plays a vital role in new product design. When designing components with a complex geometry and/or complex loading, the nonlinear elastic-plastic analysis method is recommended in the ASME Boiler and Pressure Vessel Code (BPVC). However, the true stress and true strain material curve must be calculated first before elastic-plastic analysis can be performed. ASME BPVC has provided the method to calculate the material curve, but first, the user has to decide how many data points to use in Ansys. Next, the user needs to pick a plasticity model to generate the curve for simulation. This paper describes how Ansys uses the data points in the material curve to calculate the stress and strain, specifically the sublayer or overlay model, in which the material is assumed to be composed of a number of sublayers or subvolumes. In addition, it includes case studies that evaluate the impact of data point numbers in the material curve on the Ansys simulation accuracy and solve time. It was discovered that the simulation accuracy was slightly affected by the data point numbers in the material curve; however, the data point numbers can have a significant effect on the solve time of each iteration: the more data point numbers, the more solve time for each iteration.
{"title":"How Data Point Numbers in Material Curve Affect Ansys Mechanical Simulation","authors":"Qi Li, Rafal Sulwinksi","doi":"10.1115/pvp2022-84254","DOIUrl":"https://doi.org/10.1115/pvp2022-84254","url":null,"abstract":"\u0000 Finite element analysis (FEA) plays a vital role in new product design. When designing components with a complex geometry and/or complex loading, the nonlinear elastic-plastic analysis method is recommended in the ASME Boiler and Pressure Vessel Code (BPVC). However, the true stress and true strain material curve must be calculated first before elastic-plastic analysis can be performed.\u0000 ASME BPVC has provided the method to calculate the material curve, but first, the user has to decide how many data points to use in Ansys. Next, the user needs to pick a plasticity model to generate the curve for simulation.\u0000 This paper describes how Ansys uses the data points in the material curve to calculate the stress and strain, specifically the sublayer or overlay model, in which the material is assumed to be composed of a number of sublayers or subvolumes. In addition, it includes case studies that evaluate the impact of data point numbers in the material curve on the Ansys simulation accuracy and solve time. It was discovered that the simulation accuracy was slightly affected by the data point numbers in the material curve; however, the data point numbers can have a significant effect on the solve time of each iteration: the more data point numbers, the more solve time for each iteration.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73915575","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}
E. Feulvarch, A. Wasylyk, Abdelhak Benrabia, Divjot Jolly, P. Duranton
In the field of numerical simulation, mesh-morphing is a technique that can be used to modify an existing Finite Element Mesh by the means of applying a specific distortion. Most of mesh-morphing methods simply change the positions of the nodes, hence the initial mesh connectivity, as well as the material properties are retained, and the boundary conditions, loadings, contact settings, etc. can be applied without any change in the input file. In this way, a simulation model can be quickly adapted with regards to any changes in the geometry or a new geometry can be created without using a CAD model. This article introduces the concept of mesh morphing using only standard Finite Element Analysis software features. The presented morphing method is used to modify a complicated mesh given a sample of displacements at known locations. Like standard morphing techniques based on the Radial Basis Functions, a weight function is calculated for each node by using steady state thermal calculation. Then, displacements at known locations are imposed to some nodes and a standard mechanical equation system is solved to calculate the displacements of all the nodes of the structure. The presented method was applied to solve some industrial applications for Class 1 Nuclear components which are showed here in order to illustrate the method.
{"title":"Mesh Morphing Based on Standard FEA Software Features and Application to Crack Propagation","authors":"E. Feulvarch, A. Wasylyk, Abdelhak Benrabia, Divjot Jolly, P. Duranton","doi":"10.1115/pvp2022-78445","DOIUrl":"https://doi.org/10.1115/pvp2022-78445","url":null,"abstract":"\u0000 In the field of numerical simulation, mesh-morphing is a technique that can be used to modify an existing Finite Element Mesh by the means of applying a specific distortion. Most of mesh-morphing methods simply change the positions of the nodes, hence the initial mesh connectivity, as well as the material properties are retained, and the boundary conditions, loadings, contact settings, etc. can be applied without any change in the input file. In this way, a simulation model can be quickly adapted with regards to any changes in the geometry or a new geometry can be created without using a CAD model.\u0000 This article introduces the concept of mesh morphing using only standard Finite Element Analysis software features. The presented morphing method is used to modify a complicated mesh given a sample of displacements at known locations. Like standard morphing techniques based on the Radial Basis Functions, a weight function is calculated for each node by using steady state thermal calculation. Then, displacements at known locations are imposed to some nodes and a standard mechanical equation system is solved to calculate the displacements of all the nodes of the structure.\u0000 The presented method was applied to solve some industrial applications for Class 1 Nuclear components which are showed here in order to illustrate the method.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"128 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74984484","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}
S. Fini, D. Croccolo, M. De Agostinis, G. Olmi, F. Robusto, C. Scapecchi
The aim of this present paper is to investigate the influence of some joint design parameters on the fatigue strength of metric screws. This investigation involved different screws strength grades (8.8 and 12.9). The experimental tests were carried out on black oxidized M6 screws, coupled with steel nuts of the corresponding strength class. Both screws and nuts were tested in “as received” lubrication condition. The screws were tested untightened and tightened with the tightening torque causing yielding (100% of the yield stress). A preliminary test to evaluate the tightening torque providing the desired equivalent stress on the screw was carried out. A tightening machine bench which was able to measure the tightening load and the friction coefficients both in the underhead and in the thread was used. The tests were run controlling the tightening torque and the spindle speed. In the following tests, the screws were tightened at the desired tightening torque and then untightened by means of the aforementioned tightening machine bench. Then the screws and the nuts were assembled on an ad hoc test fixture and tested on a resonant testing machine in order to evaluate the screw fatigue limit according to the international standard ISO 3800. The experimental results were processed by means of statistical tools of two-way ANOVA and Fisher Test in order to evaluate the effect of each parameter on the fatigue response of the screws.
{"title":"Experimental Investigation on the Fatigue Strength for Different Tightening Procedures and Materials in Metric Screws","authors":"S. Fini, D. Croccolo, M. De Agostinis, G. Olmi, F. Robusto, C. Scapecchi","doi":"10.1115/pvp2022-84644","DOIUrl":"https://doi.org/10.1115/pvp2022-84644","url":null,"abstract":"\u0000 The aim of this present paper is to investigate the influence of some joint design parameters on the fatigue strength of metric screws. This investigation involved different screws strength grades (8.8 and 12.9). The experimental tests were carried out on black oxidized M6 screws, coupled with steel nuts of the corresponding strength class. Both screws and nuts were tested in “as received” lubrication condition. The screws were tested untightened and tightened with the tightening torque causing yielding (100% of the yield stress). A preliminary test to evaluate the tightening torque providing the desired equivalent stress on the screw was carried out. A tightening machine bench which was able to measure the tightening load and the friction coefficients both in the underhead and in the thread was used. The tests were run controlling the tightening torque and the spindle speed. In the following tests, the screws were tightened at the desired tightening torque and then untightened by means of the aforementioned tightening machine bench. Then the screws and the nuts were assembled on an ad hoc test fixture and tested on a resonant testing machine in order to evaluate the screw fatigue limit according to the international standard ISO 3800. The experimental results were processed by means of statistical tools of two-way ANOVA and Fisher Test in order to evaluate the effect of each parameter on the fatigue response of the screws.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"56 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73045582","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}
Branch Technical Position (BTP) 3-4 provides a guideline to determine postulated rupture locations for ASME Class 1 piping. This guideline contains criteria related to the maximum cyclic stress ranges and cumulative usage factor (CUF) by using only NB-3600-based procedure which may have conservative analysis results for determining postulated rupture locations. Recently issued BTP 3-4 Rev.3 provides two different CUF limits of 0.1 for air environments and 0.4 for Light Water Reactor (LWR) environments, respectively, for determining postulated rupture locations. To calculate CUFen considering the effects of the LWR environments, the fatigue usage factor determined in the air environments based on NB-3200 or NB-3600 of ASME B&PV Sec. III is multiplied by the environmental fatigue correction factor (Fen) based on Regulatory Guide 1.207 (RG 1.207). The Fen values may vary depending on the LWR environment conditions and the maximum Fen can be determined as a factor of approximately 14 for stainless steels. Also, RG 1.207 requires to use the new design fatigue curves (DFC), which have been developed recently by Argonne National Laboratory, to perform the environmental fatigue analysis. Since the new DFC predicts much shorter fatigue lives than the current DFC given in ASME B&PV Sec. III for stainless steels, the CUFen in the LWR environments could be significantly increased. For these reasons, many points in piping systems could be determined to be postulated rupture locations due to exceeding the CUFen limit of 0.4 in the LWR environments. In this paper, NB-3200- and NB-3600-based stress analyses and fatigue analyses considering both the air environments and the LWR environments for the safety injection (SI) piping have been performed to evaluate the conservatism of NB-3600-based stress analysis results and to review the effects of the LWR environments for determining postulated rupture locations.
{"title":"ASME Sec. III NB-3200-Based Environmental Fatigue Analysis of Safety Injection Piping for Determining Postulated Rupture Locations","authors":"B. Lee, I. Nam, Wooseok Yang, C. Lee, Dongjae Lee","doi":"10.1115/pvp2022-81565","DOIUrl":"https://doi.org/10.1115/pvp2022-81565","url":null,"abstract":"\u0000 Branch Technical Position (BTP) 3-4 provides a guideline to determine postulated rupture locations for ASME Class 1 piping. This guideline contains criteria related to the maximum cyclic stress ranges and cumulative usage factor (CUF) by using only NB-3600-based procedure which may have conservative analysis results for determining postulated rupture locations.\u0000 Recently issued BTP 3-4 Rev.3 provides two different CUF limits of 0.1 for air environments and 0.4 for Light Water Reactor (LWR) environments, respectively, for determining postulated rupture locations. To calculate CUFen considering the effects of the LWR environments, the fatigue usage factor determined in the air environments based on NB-3200 or NB-3600 of ASME B&PV Sec. III is multiplied by the environmental fatigue correction factor (Fen) based on Regulatory Guide 1.207 (RG 1.207). The Fen values may vary depending on the LWR environment conditions and the maximum Fen can be determined as a factor of approximately 14 for stainless steels. Also, RG 1.207 requires to use the new design fatigue curves (DFC), which have been developed recently by Argonne National Laboratory, to perform the environmental fatigue analysis. Since the new DFC predicts much shorter fatigue lives than the current DFC given in ASME B&PV Sec. III for stainless steels, the CUFen in the LWR environments could be significantly increased.\u0000 For these reasons, many points in piping systems could be determined to be postulated rupture locations due to exceeding the CUFen limit of 0.4 in the LWR environments.\u0000 In this paper, NB-3200- and NB-3600-based stress analyses and fatigue analyses considering both the air environments and the LWR environments for the safety injection (SI) piping have been performed to evaluate the conservatism of NB-3600-based stress analysis results and to review the effects of the LWR environments for determining postulated rupture locations.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"92 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79260703","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}
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