Class 1 nuclear piping systems, small-bore piping branch connections are susceptible to high thermal fatigue stresses, particularly in cases where harsh thermal transients are present. Calculating the Cumulative Usage Factor (CUF) using the procedure defined in the ASME Boiler and Pressure Vessel Code in Section III NB-3600 can limit the permissible cycle life (i.e., fatigue life) of the piping component. As per NB-3630(c), when a design does not satisfy the requirements of NB-3640 and NB-3650, a more detailed alternative analysis defined in NB-3200 can be used. This work compares the code requirements, analysis methodology, and results of a typical small bore branch connection connected to a piping header that is assessed against the requirements of NB-3600 and NB-3200. Piping is modeled using beam elements by utilizing PIPESTRESS piping analysis software for the NB-3600 based analysis. In comparison, a finite element model in Ansys Workbench is developed for the NB-3200 transient thermal and structural analysis. Representative pressure and thermal transients applicable to the heat transport system of a typical CANDU reactor are utilized in the analysis. The analysis results show that a significant drop in the Cumulative Usage Factor is achieved with the NB-3200 approach when compared with NB-3600.
{"title":"Fatigue Analysis of Nuclear Class-1 Small-Bore Piping Connections in CANDU Reactors","authors":"S. A. Rehman, Ahmed R. Alian, Najmul H. Abid","doi":"10.1115/pvp2022-84938","DOIUrl":"https://doi.org/10.1115/pvp2022-84938","url":null,"abstract":"\u0000 Class 1 nuclear piping systems, small-bore piping branch connections are susceptible to high thermal fatigue stresses, particularly in cases where harsh thermal transients are present. Calculating the Cumulative Usage Factor (CUF) using the procedure defined in the ASME Boiler and Pressure Vessel Code in Section III NB-3600 can limit the permissible cycle life (i.e., fatigue life) of the piping component. As per NB-3630(c), when a design does not satisfy the requirements of NB-3640 and NB-3650, a more detailed alternative analysis defined in NB-3200 can be used. This work compares the code requirements, analysis methodology, and results of a typical small bore branch connection connected to a piping header that is assessed against the requirements of NB-3600 and NB-3200. Piping is modeled using beam elements by utilizing PIPESTRESS piping analysis software for the NB-3600 based analysis. In comparison, a finite element model in Ansys Workbench is developed for the NB-3200 transient thermal and structural analysis. Representative pressure and thermal transients applicable to the heat transport system of a typical CANDU reactor are utilized in the analysis. The analysis results show that a significant drop in the Cumulative Usage Factor is achieved with the NB-3200 approach when compared with NB-3600.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"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":"82863029","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}
Spherical pressure vessels (spheres) are widely used for storing liquids and gases at high pressures. The post plates of column-supported spheres are subjected to additional loads imposed by the supporting columns. The resulting localized stresses at column-to-post plate junction are difficult to analyze using analytical methods. Numerical techniques, such as the finite element method (FEM) are generally used to analyze the local discontinuity stresses. In this work, a finite element parametric study is performed using a wide range of sphere geometries. The stresses at various locations around the column attachment are investigated. The influence of various loadings on the local stresses is also investigated. The internal membrane forces and bending moments obtained from the finite element model are then used to establish the dimensionless curves. A step-by-step procedure and the closed-form equations are provided to calculate membrane stresses, bending stresses and the combined stresses. A table of load factors is included to estimate the maximum vertical and horizontal loads on post plate due to wind or seismic forces. Finally, a sample problem is presented to illustrate the analysis procedure. Using this easy-to-use analysis approach, the design engineers will be able to calculate the localized stresses in sphere post plates without having to utilize the finite element method.
{"title":"Evaluation of Localized Stresses at Spherical Pressure Vessel-to-Column Support Junction Using Closed-Form Equations","authors":"Vivek Manjrekar","doi":"10.1115/pvp2022-84890","DOIUrl":"https://doi.org/10.1115/pvp2022-84890","url":null,"abstract":"\u0000 Spherical pressure vessels (spheres) are widely used for storing liquids and gases at high pressures. The post plates of column-supported spheres are subjected to additional loads imposed by the supporting columns. The resulting localized stresses at column-to-post plate junction are difficult to analyze using analytical methods. Numerical techniques, such as the finite element method (FEM) are generally used to analyze the local discontinuity stresses.\u0000 In this work, a finite element parametric study is performed using a wide range of sphere geometries. The stresses at various locations around the column attachment are investigated. The influence of various loadings on the local stresses is also investigated. The internal membrane forces and bending moments obtained from the finite element model are then used to establish the dimensionless curves. A step-by-step procedure and the closed-form equations are provided to calculate membrane stresses, bending stresses and the combined stresses. A table of load factors is included to estimate the maximum vertical and horizontal loads on post plate due to wind or seismic forces. Finally, a sample problem is presented to illustrate the analysis procedure. Using this easy-to-use analysis approach, the design engineers will be able to calculate the localized stresses in sphere post plates without having to utilize the finite element method.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75012306","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}
To mitigate the severe effects in the beyond design basis accident (BDBA), the concept of fracture control was proposed in the previous study. The idea of the fracture control is to manage the accident consequence by controlling to cause minor failure prior to the fatal failure. Taking the piping system as an example, boundary failure should be prevented under the BDBA condition, whereas the minor failure, such as support failure which does not affect the function of the piping system, can be acceptable. To realize the fracture control concept on piping system, shaking table tests on piping systems with support are planned. As the first step of the attempt, fundamental experiment on relatively simple piping system and support configuration was conducted. In this experiment, pipe elbows made of simulation material (lead-antimony alloy) were used, and the support was modeled by a plate. Through the experiments, the fracture of support successfully occurred prior to the large deformation of pipe itself. The results showed that the fracture control may be possible when the fracture of support occurred prior to the failure of pipe itself, and the ratio of the input frequency to the specimen’s natural frequency (fR) be over 1.0 after the support failure. The test results demonstrated the possibility of fracture control concept by support failure. As the next step of the attempt, shaking table test on more realistic piping system, which is named as validation test, is now prepared. The preliminary analysis shows that the inelastic behavior of support is expected.
{"title":"Plan of a Shaking Table Test on a Piping System Model for Verifying the Fracture-Control Concept","authors":"Izumi Nakamura, N. Kasahara","doi":"10.1115/pvp2022-84266","DOIUrl":"https://doi.org/10.1115/pvp2022-84266","url":null,"abstract":"\u0000 To mitigate the severe effects in the beyond design basis accident (BDBA), the concept of fracture control was proposed in the previous study. The idea of the fracture control is to manage the accident consequence by controlling to cause minor failure prior to the fatal failure.\u0000 Taking the piping system as an example, boundary failure should be prevented under the BDBA condition, whereas the minor failure, such as support failure which does not affect the function of the piping system, can be acceptable.\u0000 To realize the fracture control concept on piping system, shaking table tests on piping systems with support are planned. As the first step of the attempt, fundamental experiment on relatively simple piping system and support configuration was conducted. In this experiment, pipe elbows made of simulation material (lead-antimony alloy) were used, and the support was modeled by a plate. Through the experiments, the fracture of support successfully occurred prior to the large deformation of pipe itself. The results showed that the fracture control may be possible when the fracture of support occurred prior to the failure of pipe itself, and the ratio of the input frequency to the specimen’s natural frequency (fR) be over 1.0 after the support failure. The test results demonstrated the possibility of fracture control concept by support failure.\u0000 As the next step of the attempt, shaking table test on more realistic piping system, which is named as validation test, is now prepared. The preliminary analysis shows that the inelastic behavior of support is expected.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"73 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84326800","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}
In the pressure equipment industry, codes of construction stipulate that fastener assemblies shall exhibit thread engagement through the full depth of the nut. In many older facilities and in locations with poor quality control, assemblies may be found on in-service equipment which do not have full thread engagement and do not meet the requirements of the code of construction. This is often found during the routine visual inspection of equipment and is flagged as a construction code deficiency requiring attention. Current post construction code guidance on fastener assemblies is ambiguous on how to handle fasteners with less-than-full thread engagement exceeding one thread of shortfall. The perceived risk of such a lack of thread engagement may lead maintenance organizations to perform costly and high-risk remediation activities, such as in-service “clamping” or “single stud replacement,” also known as “hot-bolting.” However, in many situations, fastener assembly strength can be proven to be sufficient for a given joint through analytical evaluation. Using a combination of innovative and existing thread strength and flanged joint considerations, the minimum required length of engagement, and, thus, the maximum allowable lack of engagement, can be safely determined for most fasteners on flange connections. This paper reviews some of the most important fastener strength considerations to propose a post-construction evaluation technique to determine the fitness for service of less-than-fully engaged fastener assemblies.
{"title":"Stud Bolt Thread Engagement: A Fitness for Service Approach","authors":"Colton M. Cranford","doi":"10.1115/pvp2022-84722","DOIUrl":"https://doi.org/10.1115/pvp2022-84722","url":null,"abstract":"\u0000 In the pressure equipment industry, codes of construction stipulate that fastener assemblies shall exhibit thread engagement through the full depth of the nut. In many older facilities and in locations with poor quality control, assemblies may be found on in-service equipment which do not have full thread engagement and do not meet the requirements of the code of construction. This is often found during the routine visual inspection of equipment and is flagged as a construction code deficiency requiring attention. Current post construction code guidance on fastener assemblies is ambiguous on how to handle fasteners with less-than-full thread engagement exceeding one thread of shortfall. The perceived risk of such a lack of thread engagement may lead maintenance organizations to perform costly and high-risk remediation activities, such as in-service “clamping” or “single stud replacement,” also known as “hot-bolting.” However, in many situations, fastener assembly strength can be proven to be sufficient for a given joint through analytical evaluation. Using a combination of innovative and existing thread strength and flanged joint considerations, the minimum required length of engagement, and, thus, the maximum allowable lack of engagement, can be safely determined for most fasteners on flange connections. This paper reviews some of the most important fastener strength considerations to propose a post-construction evaluation technique to determine the fitness for service of less-than-fully engaged fastener assemblies.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89618856","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}
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}
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}
This study outlines the application of a Reduced Order Modeling (ROM) approach for the probabilistic creep response of components subject to creep conditions. Time-dependent creep damage is unavoidably inflicted in elevated temperature. Typical operating condition fluctuations experienced during service can greatly limit creep life when compared to the ideal design conditions. To mimic the uncertainty in component, probabilistic Finite Element Analysis (FEA) can be employed; however, numerous full-field FEA simulations (103−105 trials) for probabilistic assessments are time-intensive and computationally prohibitive. To address this challenge, the computationally efficient ROM approach is introduced for probabilistic creep deformation, damage, and rupture predictions in FEA. In this approach, full-scale probabilistic simulation using a 1D model are performed, the extremum conditions retrieved, and applied in 2D/3D model simulations to capture the scatter bands of component response. The Wilshire-Cano-Stewart (WCS) model is calibrated to quintuplicate 304 Stainless steel data. Test condition, initial damage, and material property uncertainty are incorporated into the WCS model via appropriate probability distribution function (pdfs). A USERCREEP.F material model is developed for the WCS model and compiled for ANSYS FEA simulations. Deterministic simulations of the WCS model are carried out in FEA for validation. The goodness-of-fit between the prediction and experiment are observed to be satisfactory. Probabilistic predictions are executed in the 1D model to generate the creep deformation, damage, and rupture prediction. The extremum cases of ductility, rupture, and area under creep (AUC) curves are established. The extremum cases alone are simulated using a 2D model to capture the component level uncertainty. A %Error statistical analysis is performed to verify the accuracy of ROM approach and further validate the approach for proposed simulation of a complex geometry (e.g., turbine blade) at a significantly reduced computational time and memory. Future investigations will introduce stochasticity, temporal, and spatial uncertainty for component-level simulation and improved prediction.
{"title":"A Reduced Order Modeling in Finite Element for Rapid Qualification of Creep-Resistant Alloys","authors":"Md. Abir Hossain, C. Stewart","doi":"10.1115/pvp2022-82065","DOIUrl":"https://doi.org/10.1115/pvp2022-82065","url":null,"abstract":"\u0000 This study outlines the application of a Reduced Order Modeling (ROM) approach for the probabilistic creep response of components subject to creep conditions. Time-dependent creep damage is unavoidably inflicted in elevated temperature. Typical operating condition fluctuations experienced during service can greatly limit creep life when compared to the ideal design conditions. To mimic the uncertainty in component, probabilistic Finite Element Analysis (FEA) can be employed; however, numerous full-field FEA simulations (103−105 trials) for probabilistic assessments are time-intensive and computationally prohibitive. To address this challenge, the computationally efficient ROM approach is introduced for probabilistic creep deformation, damage, and rupture predictions in FEA. In this approach, full-scale probabilistic simulation using a 1D model are performed, the extremum conditions retrieved, and applied in 2D/3D model simulations to capture the scatter bands of component response. The Wilshire-Cano-Stewart (WCS) model is calibrated to quintuplicate 304 Stainless steel data. Test condition, initial damage, and material property uncertainty are incorporated into the WCS model via appropriate probability distribution function (pdfs). A USERCREEP.F material model is developed for the WCS model and compiled for ANSYS FEA simulations. Deterministic simulations of the WCS model are carried out in FEA for validation. The goodness-of-fit between the prediction and experiment are observed to be satisfactory. Probabilistic predictions are executed in the 1D model to generate the creep deformation, damage, and rupture prediction. The extremum cases of ductility, rupture, and area under creep (AUC) curves are established. The extremum cases alone are simulated using a 2D model to capture the component level uncertainty. A %Error statistical analysis is performed to verify the accuracy of ROM approach and further validate the approach for proposed simulation of a complex geometry (e.g., turbine blade) at a significantly reduced computational time and memory. Future investigations will introduce stochasticity, temporal, and spatial uncertainty for component-level simulation and improved prediction.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"460 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86026618","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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