Nicolas Jacquet, N. Tardif, T. Elguedj, C. Garnier
This work is focused on elasto-visco-plastic (EVP) buckling of thick shell structures. In particular we are interested in predicting accurately the buckling risk of stainless steel components of nuclear fast sodium reactor working under high pressure and at high temperature (around 180 bar and 500 °C). We follow a modeling/experimental approach to solve this problem. The set-up of relevant experiments at such high temperature being complex, we work with a representative material that shows similar EVP and buckling behavior at room temperature. The representative material is an alloy mostly composed of tin, silver and copper, commonly named Sn 3.0 Ag 0.5 Cu. The elasto-visco-plastic constitutive model of the material was first characterized using tensile tests on notched specimen at room temperature under various strain rates, and the model parameters identified using finite element model updating (FEMU). In a second step we performed in plane compressive buckling tests of thick plates for various displacement rates. Surface 3D displacements were acquired using three cameras and digital image correlation. It is well known for thick plates that linearized tangent moduli derived from Levy-Mises flow theory does not give accurate elasto-plastic buckling prediction. Linearized tangent moduli derived from Hencky’s deformation theory gives more accurate buckling prediction for thick plates. This numerical phenomenon known as buckling paradox was well correlated to experiments in the literature. This paradox is applied here to thick plates, with EVP constitutive model, in order to predict buckling. Finally, finite element (FE) modeling of the buckling experiments was performed. Plates are modeled using SHB8PS solid shell elements. Solid shell elements allow direct displacement correlation with experiments and accurate through the thickness behavior with a 3D material model. The numerical modeling includes real plate geometry obtained using post machining measurements, experimental boundary conditions derived from the DIC (Digital Image Correlation) results and the previously identified constitutive material law. Buckling risk is tested at each loading step of the incremental algorithm using the tangent operator derived with the Hencky’s deformation theory. Numerical results show a very good correlation with the experimental results on load and displacement history as well as buckling critical load and buckling mode.
本文主要研究厚壳结构的弹粘塑性屈曲问题。我们特别感兴趣的是准确预测在高压和高温(约180 bar和500°C)下工作的核快钠反应堆不锈钢部件的屈曲风险。我们采用建模/实验的方法来解决这个问题。在如此高的温度下进行相关实验是复杂的，我们使用了一种具有代表性的材料，在室温下表现出相似的EVP和屈曲行为。代表材料是一种主要由锡、银、铜组成的合金，俗称Sn 3.0 Ag 0.5 Cu。首先利用缺口试样在室温下不同应变速率下的拉伸试验对材料的弹粘塑性本构模型进行了表征，并利用有限元模型更新(FEMU)确定了模型参数。在第二步中，我们对不同位移率的厚板进行了平面压缩屈曲试验。利用三台相机和数字图像相关技术获得了表面三维位移。众所周知，对于厚板，由列维-米塞斯流动理论导出的线性化切模量不能给出准确的弹塑性屈曲预测。由henky变形理论推导出的线性化切模量可以更精确地预测厚板的屈曲。这种被称为屈曲悖论的数值现象与文献中的实验有很好的关联。本文将这一悖论应用于厚板，采用EVP本构模型进行屈曲预测。最后，对屈曲试验进行了有限元建模。板采用SHB8PS实体壳单元建模。实体壳单元允许与实验直接的位移关联，并通过与3D材料模型的厚度行为精确。数值模拟包括通过加工后测量获得的真实板几何形状，从DIC(数字图像相关)结果得出的实验边界条件以及先前确定的本构材料定律。利用henky变形理论导出的切线算子对增量算法的每个加载步骤进行了屈曲风险测试。数值计算结果与试验结果在载荷和位移历史、屈曲临界载荷和屈曲模态上有很好的相关性。
{"title":"Elasto-Visco-Plastic Buckling of Thick Anisotropic Shells: Numerical Buckling Predictions and Experiments","authors":"Nicolas Jacquet, N. Tardif, T. Elguedj, C. Garnier","doi":"10.1115/pvp2020-21491","DOIUrl":"https://doi.org/10.1115/pvp2020-21491","url":null,"abstract":"\u0000 This work is focused on elasto-visco-plastic (EVP) buckling of thick shell structures. In particular we are interested in predicting accurately the buckling risk of stainless steel components of nuclear fast sodium reactor working under high pressure and at high temperature (around 180 bar and 500 °C). We follow a modeling/experimental approach to solve this problem.\u0000 The set-up of relevant experiments at such high temperature being complex, we work with a representative material that shows similar EVP and buckling behavior at room temperature. The representative material is an alloy mostly composed of tin, silver and copper, commonly named Sn 3.0 Ag 0.5 Cu. The elasto-visco-plastic constitutive model of the material was first characterized using tensile tests on notched specimen at room temperature under various strain rates, and the model parameters identified using finite element model updating (FEMU). In a second step we performed in plane compressive buckling tests of thick plates for various displacement rates. Surface 3D displacements were acquired using three cameras and digital image correlation.\u0000 It is well known for thick plates that linearized tangent moduli derived from Levy-Mises flow theory does not give accurate elasto-plastic buckling prediction. Linearized tangent moduli derived from Hencky’s deformation theory gives more accurate buckling prediction for thick plates. This numerical phenomenon known as buckling paradox was well correlated to experiments in the literature. This paradox is applied here to thick plates, with EVP constitutive model, in order to predict buckling.\u0000 Finally, finite element (FE) modeling of the buckling experiments was performed. Plates are modeled using SHB8PS solid shell elements. Solid shell elements allow direct displacement correlation with experiments and accurate through the thickness behavior with a 3D material model. The numerical modeling includes real plate geometry obtained using post machining measurements, experimental boundary conditions derived from the DIC (Digital Image Correlation) results and the previously identified constitutive material law. Buckling risk is tested at each loading step of the incremental algorithm using the tangent operator derived with the Hencky’s deformation theory.\u0000 Numerical results show a very good correlation with the experimental results on load and displacement history as well as buckling critical load and buckling mode.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127569541","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}
A. Shaw, Ian W. Jentz, Heramb P. Mahajan, T. Hassan
High thermal efficiency of Compact Heat Exchangers (CHX) makes them distinctly utile for application to Next Generation Nuclear Plants (NGNPs). The high temperature application and transient conditions of NGNP operation induce stresses in CHX. These induced stresses can be categorized under different classifications based on their cause and location. ASME Sec. III Div. 5 has different analysis methodologies based on failure modes, failure criteria to be assessed, and constitutive relationship considered. The primary objective of this study is to provide a description of the classification of stresses in CHX. Further, evaluation of CHX design is conducted according to simplified analysis methodologies in ASME Sec. III Div. 5: Elastic and Simplified Inelastic Analysis. These simplified analyses are performed following the submodeling technique. At the global level, the channeled core is replaced by an elastic orthotropic core for analysis. At the local level, the stresses and strains for critical regions are determined following the simplified analysis methods. The load controlled stresses are checked against HBB-3220 of ASME Sec. III Div. 5. For the Elastic Analysis Method, strains in critical sections in CHX are checked for thermomechanical cycle against the HBB-T-1320 of ASME Sec. III Div. 5 criteria. For Simplified Inelastic Analysis, critical sections are analyzed for strain limits following HBB-T-1330 of ASME Sec. III Div. 5. The analyses outcomes are compared and results are discussed.
紧凑型热交换器(CHX)的高热效率使其非常适用于下一代核电站(NGNPs)的应用。高温应用和NGNP运行的瞬态条件在CHX中产生应力。这些诱发应力可以根据其原因和位置进行不同的分类。ASME Sec. III Div. 5基于失效模式、要评估的失效准则和考虑本构关系有不同的分析方法。本研究的主要目的是提供对CHX应力分类的描述。此外，根据ASME第III节第5节:弹性和简化非弹性分析中的简化分析方法对CHX设计进行评估。这些简化的分析是按照子建模技术执行的。在全局水平上，通道核被弹性正交各向异性核取代以进行分析。在局部，采用简化的分析方法确定了关键区域的应力和应变。负载控制应力根据ASME第III节第5节的HBB-3220进行校核。对于弹性分析方法，CHX临界截面的应变根据ASME section III Div. 5标准的HBB-T-1320进行热机械循环检查。对于简化非弹性分析，根据ASME第III节第5节的HBB-T-1330对临界截面进行应变极限分析。对分析结果进行了比较和讨论。
{"title":"Assessment of Compact Heat Exchanger Design According to the Simplified ASME Analysis Methodologies","authors":"A. Shaw, Ian W. Jentz, Heramb P. Mahajan, T. Hassan","doi":"10.1115/pvp2020-21547","DOIUrl":"https://doi.org/10.1115/pvp2020-21547","url":null,"abstract":"\u0000 High thermal efficiency of Compact Heat Exchangers (CHX) makes them distinctly utile for application to Next Generation Nuclear Plants (NGNPs). The high temperature application and transient conditions of NGNP operation induce stresses in CHX. These induced stresses can be categorized under different classifications based on their cause and location. ASME Sec. III Div. 5 has different analysis methodologies based on failure modes, failure criteria to be assessed, and constitutive relationship considered. The primary objective of this study is to provide a description of the classification of stresses in CHX. Further, evaluation of CHX design is conducted according to simplified analysis methodologies in ASME Sec. III Div. 5: Elastic and Simplified Inelastic Analysis. These simplified analyses are performed following the submodeling technique. At the global level, the channeled core is replaced by an elastic orthotropic core for analysis. At the local level, the stresses and strains for critical regions are determined following the simplified analysis methods. The load controlled stresses are checked against HBB-3220 of ASME Sec. III Div. 5. For the Elastic Analysis Method, strains in critical sections in CHX are checked for thermomechanical cycle against the HBB-T-1320 of ASME Sec. III Div. 5 criteria. For Simplified Inelastic Analysis, critical sections are analyzed for strain limits following HBB-T-1330 of ASME Sec. III Div. 5. The analyses outcomes are compared and results are discussed.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126920729","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}
There is increased interest in the application of compact heat exchangers (CHXs) for nuclear service given their high thermal efficiency and compactness. CHXs are fabricated by joining a stack of etched plates with dense microchannels through diffusion bonding. Diffusion bonding material has basic mechanical properties that differ from a base material, requiring appropriate mechanical properties and allowable stresses for design. Existing nuclear code ASME Section III, Division 5 does not address diffusion bonded materials . Hence, there is a need to develop material properties and allowable stresses of diffusion bonded materials and weldments. In this paper, one candidate material, Alloy 800H, was selected for diffusion bonding trials. Preliminary results obtained from a series of tensile and creep tests suggest that the diffusion bonded material is weaker than the base metal 800H. These experimental data are used in determining recommended allowable stresses of the diffusion bonded 800H material. In this paper, tables of the strength reduction factors for various allowable stresses which includes Smt, So, St, Sy and Su for diffusion bonded Alloy 800H are presented. These reduction factors are applicable to CHX design. The Larson Miller Parameter (LMP) is used to extrapolate short term creep tests to longer creep life and lower temperatures, and estimate the onset of tertiary creep strain.
{"title":"Allowable Stress Development of Diffusion Bonded Alloy 800H for Section III","authors":"Heramb P. Mahajan, Ian W. Jentz, T. Hassan","doi":"10.1115/pvp2020-21499","DOIUrl":"https://doi.org/10.1115/pvp2020-21499","url":null,"abstract":"\u0000 There is increased interest in the application of compact heat exchangers (CHXs) for nuclear service given their high thermal efficiency and compactness. CHXs are fabricated by joining a stack of etched plates with dense microchannels through diffusion bonding. Diffusion bonding material has basic mechanical properties that differ from a base material, requiring appropriate mechanical properties and allowable stresses for design. Existing nuclear code ASME Section III, Division 5 does not address diffusion bonded materials . Hence, there is a need to develop material properties and allowable stresses of diffusion bonded materials and weldments. In this paper, one candidate material, Alloy 800H, was selected for diffusion bonding trials. Preliminary results obtained from a series of tensile and creep tests suggest that the diffusion bonded material is weaker than the base metal 800H. These experimental data are used in determining recommended allowable stresses of the diffusion bonded 800H material. In this paper, tables of the strength reduction factors for various allowable stresses which includes Smt, So, St, Sy and Su for diffusion bonded Alloy 800H are presented. These reduction factors are applicable to CHX design. The Larson Miller Parameter (LMP) is used to extrapolate short term creep tests to longer creep life and lower temperatures, and estimate the onset of tertiary creep strain.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"199 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129537942","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 finite element analysis of large-scale heat exchangers, the tightness analysis of tube-to-tubesheet joints of heat exchanger is classified into a highly nonlinear problem due to the existence of contact between tube and tubesheet, and there are a large number of tubes in the heat exchanger. These all make it difficult to analyze the tube-to-tubesheet joints in detail with the full model method. The traditional local model method simplifies the problem in a certain extent, but its boundary condition is different from the actual situation, which will result in an inaccurate result. In this paper, the sub model method is introduced into the tightness analysis of tube-to-tubesheet joints of the heat exchanger. Taking a U-tube heat exchanger as an example, the traditional local model method and the sub model method are used to analyze the tightness of tube-to-tubesheet joints respectively. The residual contact pressure of the seal ring on the contact surface of tube-to-tubesheet joints is taken as the criterion to evaluate the tightness of the joint. Variations of the residual contact pressure obtained by the two methods are comparatively studied. It is found that the traditional local model method is not conservative enough compared with the sub model method, and the sub model method can simulate more real boundary condition and obtain tightness conditions of the joint in different locations,which is a more effective analysis method. In addition, it is found that the choice of cutting boundary of the sub model has certain influence on the analysis results.
{"title":"A Comparative Study on the Sub-Model Method and the Local Model Method in the Tightness Analysis of Tube-to-Tubesheet Joints of Heat Exchanger","authors":"Xiangbing Zhang, Chenghong Duan, Xiangpeng Luo, Jinhao Huang","doi":"10.1115/pvp2020-21048","DOIUrl":"https://doi.org/10.1115/pvp2020-21048","url":null,"abstract":"\u0000 In the finite element analysis of large-scale heat exchangers, the tightness analysis of tube-to-tubesheet joints of heat exchanger is classified into a highly nonlinear problem due to the existence of contact between tube and tubesheet, and there are a large number of tubes in the heat exchanger. These all make it difficult to analyze the tube-to-tubesheet joints in detail with the full model method. The traditional local model method simplifies the problem in a certain extent, but its boundary condition is different from the actual situation, which will result in an inaccurate result. In this paper, the sub model method is introduced into the tightness analysis of tube-to-tubesheet joints of the heat exchanger. Taking a U-tube heat exchanger as an example, the traditional local model method and the sub model method are used to analyze the tightness of tube-to-tubesheet joints respectively. The residual contact pressure of the seal ring on the contact surface of tube-to-tubesheet joints is taken as the criterion to evaluate the tightness of the joint. Variations of the residual contact pressure obtained by the two methods are comparatively studied. It is found that the traditional local model method is not conservative enough compared with the sub model method, and the sub model method can simulate more real boundary condition and obtain tightness conditions of the joint in different locations,which is a more effective analysis method. In addition, it is found that the choice of cutting boundary of the sub model has certain influence on the analysis results.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"164 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127316836","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 carbon-fiber wound composite gas cylinder with aluminum liner is a kind of the commonly used composite material wound gas cylinder, which has the advantages of light weight, high strength and high explosion resistance, and it has been widely used in aviation, chemical industry and other industries. As the application conditions of composite gas cylinder are more and more strict, the strength requirements of composite gas cylinder are higher, and the composite layer parameters in the manufacturing process are important factors that affect the strength of composite gas cylinder. In this paper, the finite element model of a carbon-fiber wound composite gas cylinder with aluminum liner is established by using APDL (ANSYS Parametric Design Language), and the stress distribution rules of aluminum liner and composite of gas cylinder under the conditions of autofrettage pressure, zero pressure, working pressure, hydrostatic test pressure and minimum bursting pressure is studied. The strength of the gas cylinder is evaluated according to the “DOT-CFFC” Code (basic requirements for fully wrapped carbon-fiber reinforced aluminum lined cylinders). In addition, influence rules of composite layer structure of winding mode and autofrettage on the strength and bearing capacity of gas cylinder is further explored. The work could provide reference for the practical application of carbon-fiber wound composite gas cylinder with aluminum liner.
{"title":"Strength Analysis and Influence Factors Research of Carbon-Fiber Wound Composite Gas Cylinder With Aluminum Liner","authors":"Wang Zunwu, Chenghong Duan, Xiangpeng Luo","doi":"10.1115/pvp2020-21103","DOIUrl":"https://doi.org/10.1115/pvp2020-21103","url":null,"abstract":"\u0000 The carbon-fiber wound composite gas cylinder with aluminum liner is a kind of the commonly used composite material wound gas cylinder, which has the advantages of light weight, high strength and high explosion resistance, and it has been widely used in aviation, chemical industry and other industries. As the application conditions of composite gas cylinder are more and more strict, the strength requirements of composite gas cylinder are higher, and the composite layer parameters in the manufacturing process are important factors that affect the strength of composite gas cylinder. In this paper, the finite element model of a carbon-fiber wound composite gas cylinder with aluminum liner is established by using APDL (ANSYS Parametric Design Language), and the stress distribution rules of aluminum liner and composite of gas cylinder under the conditions of autofrettage pressure, zero pressure, working pressure, hydrostatic test pressure and minimum bursting pressure is studied. The strength of the gas cylinder is evaluated according to the “DOT-CFFC” Code (basic requirements for fully wrapped carbon-fiber reinforced aluminum lined cylinders). In addition, influence rules of composite layer structure of winding mode and autofrettage on the strength and bearing capacity of gas cylinder is further explored. The work could provide reference for the practical application of carbon-fiber wound composite gas cylinder with aluminum liner.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130920173","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}
Compact Heat Exchangers (CHXs) have a large number of miniature channels inside their core, which makes them highly thermal efficient and thus, prime utile for Next Generation Nuclear Plant (NGNP) applications. The fabrication of a CHX involves diffusion, brazed or welded bonding of plates to form CHX block with a channeled core. The elevated temperature and transient conditions of NGNP operation may induce excessive strain and creep-fatigue failure in channel ligaments. The primary objective of this study is to evaluate the design of CHX for application to NGNPs, following the ASME Code Elastic Perfectly Plastic (EPP) Analysis criteria in a draft ASME Code Section III, Division 5 and using the currently available Division 5 Code Cases (N-861 and N-862). As global analysis considering channels in the core is computationally intensive, a new analysis method is evaluated. In this method, the global analysis is performed by representing the channeled core by an elastic orthotropic material core. Subsequently, at the local level, EPP analysis is performed using models that include the channels, with thermal and pressure loading conditions. An ASME Draft Code Case is under development for the construction of CHXs. The analysis results are used to assess proposed stress limits and classification for load controlled stresses. For strain limits, the analysis results are evaluated using Code Cases N-861 and N-862 against the strain limit and creep-fatigue damage using the channel level submodel analysis. The applicability of the new analysis method, and use of the analysis results for evaluation against ASME proposed limits for various regions of the CHX are presented and discussed.
{"title":"Assessment of Compact Heat Exchanger Design Following Elastic Perfectly Plastic Methodology","authors":"A. Shaw, Heramb P. Mahajan, T. Hassan","doi":"10.1115/pvp2020-21500","DOIUrl":"https://doi.org/10.1115/pvp2020-21500","url":null,"abstract":"\u0000 Compact Heat Exchangers (CHXs) have a large number of miniature channels inside their core, which makes them highly thermal efficient and thus, prime utile for Next Generation Nuclear Plant (NGNP) applications. The fabrication of a CHX involves diffusion, brazed or welded bonding of plates to form CHX block with a channeled core. The elevated temperature and transient conditions of NGNP operation may induce excessive strain and creep-fatigue failure in channel ligaments. The primary objective of this study is to evaluate the design of CHX for application to NGNPs, following the ASME Code Elastic Perfectly Plastic (EPP) Analysis criteria in a draft ASME Code Section III, Division 5 and using the currently available Division 5 Code Cases (N-861 and N-862). As global analysis considering channels in the core is computationally intensive, a new analysis method is evaluated. In this method, the global analysis is performed by representing the channeled core by an elastic orthotropic material core. Subsequently, at the local level, EPP analysis is performed using models that include the channels, with thermal and pressure loading conditions. An ASME Draft Code Case is under development for the construction of CHXs. The analysis results are used to assess proposed stress limits and classification for load controlled stresses. For strain limits, the analysis results are evaluated using Code Cases N-861 and N-862 against the strain limit and creep-fatigue damage using the channel level submodel analysis. The applicability of the new analysis method, and use of the analysis results for evaluation against ASME proposed limits for various regions of the CHX are presented and discussed.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122982131","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 paper presents an numerical study on a large unanchored open-topped steel tank. The buckling behaviors of the tank are analyzed using the finite element computer package ANSYS by means of nonlinear stabilization algorithm. The effects of foundation harmonic settlement on the elephant foot buckling strength of large unanchored open-topped oil storage tanks with tapered shells under axial compression are explored by numerical modeling. Various items of actual geometrical structure which involve concrete ringwall foundation of tank, unanchored bottom with slope, shell tapering from the base to the top, wind girders and supports, top angles, stiffening rings and support plates are presented thoroughly in the non-symmetrical 3D finite element model. Geometric nonlinearity, nonlinear boundary conditions and elastic plastic material of Ramberg-Osgood model are involved simultaneously in simulate course. The obtained solutions are displayed graphically for selected values of system parameters: harmonic settlement amplitude, harmonic number, and critical buckling stress of axially compressed oil tank. The results will provide insights into the relationship between foundation harmonic settlement and buckling strength of the large cylinders.
{"title":"Elephant Foot Buckling Analysis of Large Unanchored Oil Storage Tanks With Tapered Shells Subjected to Foundation Settlement","authors":"Lei Shi, Xiaolin Wang, Liang-Chaang Chang, Xue Li","doi":"10.1115/pvp2020-21171","DOIUrl":"https://doi.org/10.1115/pvp2020-21171","url":null,"abstract":"\u0000 This paper presents an numerical study on a large unanchored open-topped steel tank. The buckling behaviors of the tank are analyzed using the finite element computer package ANSYS by means of nonlinear stabilization algorithm. The effects of foundation harmonic settlement on the elephant foot buckling strength of large unanchored open-topped oil storage tanks with tapered shells under axial compression are explored by numerical modeling. Various items of actual geometrical structure which involve concrete ringwall foundation of tank, unanchored bottom with slope, shell tapering from the base to the top, wind girders and supports, top angles, stiffening rings and support plates are presented thoroughly in the non-symmetrical 3D finite element model. Geometric nonlinearity, nonlinear boundary conditions and elastic plastic material of Ramberg-Osgood model are involved simultaneously in simulate course. The obtained solutions are displayed graphically for selected values of system parameters: harmonic settlement amplitude, harmonic number, and critical buckling stress of axially compressed oil tank. The results will provide insights into the relationship between foundation harmonic settlement and buckling strength of the large cylinders.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117307370","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. Sasaki, Takanori Nanjo, Toshikazu Miyashita, S. Kataoka, Yoshiaki Uno
The skirt and shell thicknesses of vertical tall pressure vessels are sometimes much increased in FPSO (Floating Production, Storage and Offloading) due to ship motion acceleration. In that case, intermediate support is used as an additional support from steel structure surrounding the vessels. By theoretical calculation, Nanjo et.al. introduced dimensionless parameter N that can represent stiffness of pressure vessel and acceleration load with the assumption of structure drift at intermediate support [1]. The authors proposed N-chart to investigate the necessity and effective elevation of intermediate support by using the parameter N. The flexibility of steel structure on the bottom affects the function of intermediate support (e.g. increasing reaction force at intermediate support, effect on bottom skirt calculation); however, the flexibility is not included in the parameter N. In this paper, an additional factor for the flexibility was studied and introduced by structural analysis. A model with flexibility of structure supporting the bottom skirt was used for the analysis. The variable flexibility of steel structure was applied to the bottom of the model to study the impact of bottom structure flexibility on the pressure vessel design. The analysis result was compared with the bottom fixed model without structure flexibility to study an additional factor. Finally, appropriate design approach for tall pressure vessels with intermediate supports was proposed.
{"title":"Study on Design Approach for Tall Pressure Vessels With Intermediate Support in Consideration of Bottom Structure Flexibility","authors":"S. Sasaki, Takanori Nanjo, Toshikazu Miyashita, S. Kataoka, Yoshiaki Uno","doi":"10.1115/pvp2020-21393","DOIUrl":"https://doi.org/10.1115/pvp2020-21393","url":null,"abstract":"\u0000 The skirt and shell thicknesses of vertical tall pressure vessels are sometimes much increased in FPSO (Floating Production, Storage and Offloading) due to ship motion acceleration. In that case, intermediate support is used as an additional support from steel structure surrounding the vessels. By theoretical calculation, Nanjo et.al. introduced dimensionless parameter N that can represent stiffness of pressure vessel and acceleration load with the assumption of structure drift at intermediate support [1]. The authors proposed N-chart to investigate the necessity and effective elevation of intermediate support by using the parameter N. The flexibility of steel structure on the bottom affects the function of intermediate support (e.g. increasing reaction force at intermediate support, effect on bottom skirt calculation); however, the flexibility is not included in the parameter N. In this paper, an additional factor for the flexibility was studied and introduced by structural analysis. A model with flexibility of structure supporting the bottom skirt was used for the analysis. The variable flexibility of steel structure was applied to the bottom of the model to study the impact of bottom structure flexibility on the pressure vessel design. The analysis result was compared with the bottom fixed model without structure flexibility to study an additional factor. Finally, appropriate design approach for tall pressure vessels with intermediate supports was proposed.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123272376","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 investigate the failure behavior of piping systems under excessive seismic loads, shaking table tests on piping system models made of a simulation material have been executed. The simulation material adopted in the experiment was lead-antimony (Pb-Sb) alloy. The piping system model was composed of two elbows made of Pb-Sb alloy, one additional mass, and two fixed anchors. Input motions were sinusoidal wave. The failure modes of the piping system were examined by varying the additional mass and frequency of the input sinusoidal wave. Through the excitation tests, the failure mode which was named as “ratchet and subsequent collapse” was obtained successfully. The result which was classified as “no failure after 500 cycles” was also obtained. It was found that the occurrence of the failure depended on the ratio of the input frequency to the specimen’s natural frequency, and the ratio of additional mass weight to the limit mass weight. Though the effect of higher modes on the failure behavior was necessary to be more investigated, it seemed that the tendency of dominant failure behavior was similar to that of the single-elbow specimen investigated in the previous study. Moreover, it was confirmed that the experimental approach to use a simulation material was applicable for piping system model with multiple elbows.
{"title":"Investigation on Failure Behavior of Two-Elbow Piping System Models Made of the Simulation Material Under Excessive Seismic Loads","authors":"Izumi Nakamura, N. Kasahara","doi":"10.1115/pvp2020-21140","DOIUrl":"https://doi.org/10.1115/pvp2020-21140","url":null,"abstract":"\u0000 To investigate the failure behavior of piping systems under excessive seismic loads, shaking table tests on piping system models made of a simulation material have been executed. The simulation material adopted in the experiment was lead-antimony (Pb-Sb) alloy. The piping system model was composed of two elbows made of Pb-Sb alloy, one additional mass, and two fixed anchors. Input motions were sinusoidal wave. The failure modes of the piping system were examined by varying the additional mass and frequency of the input sinusoidal wave.\u0000 Through the excitation tests, the failure mode which was named as “ratchet and subsequent collapse” was obtained successfully. The result which was classified as “no failure after 500 cycles” was also obtained. It was found that the occurrence of the failure depended on the ratio of the input frequency to the specimen’s natural frequency, and the ratio of additional mass weight to the limit mass weight. Though the effect of higher modes on the failure behavior was necessary to be more investigated, it seemed that the tendency of dominant failure behavior was similar to that of the single-elbow specimen investigated in the previous study.\u0000 Moreover, it was confirmed that the experimental approach to use a simulation material was applicable for piping system model with multiple elbows.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128808348","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}
V. Stryzhalo, M. Zarazovskii, A. Bohdan, Z. Yaskovets, V. Antonchenko
The stress state of pipelines in areas of mine production requires obligatory consideration the influence of ground displacements. In this case the rules for design pipelines include the additional actions, such as the wall thickness increasing or U-shaped compensators installation. The Ukrainian coal mining industry requires the expanding of mine production areas. It leads to the situation where old pipelines, which are not designed for such loads, could rupture due to ground displacements. The principle of “extinguish a fire” is applied in this case. It consists in applying of stress reduction actions before certain stage of mine production (so-called lava), such as digging out long sections, cutting and sanding, which require the involvement of significant human and material resources. But, in some cases, even the large-scale application of these actions does not lead to the stress reduction to the acceptable level (especially for pipelines of diameter less then 200mm). So, to solve this problem the implementation of bellow compensators (BC) is proposed. The present work consists of: • experimental investigations of BC which are carried out in order to obtain its bearing capacity and to validate its designed parameters guaranteed by the manufacturer; • simulation of the BC loading process using FEM with adjusting the way of contact modelling between the BC layers in such manner, to be best correlate with the results of experiments; • the application of obtained results for modelling of stress state of real pipelines in the areas of coal mine production. The results of experimental investigation of BC of DN100 is presented. Their include: hydrotest with axial displacements limitation; tension-compression cycles for different values of amplitude with simultaneously loading of the operating value of gas pipeline internal pressure; rupture pressure determination. Based on the experimental results, numerical modelling and specified domestic software for stress state assessment in pipelines the optimal locations and the required number of BCs is determined for buried gas pipelines. The results of presented works allowed us not only to implement the BCs to gas pipelines DN100 in areas of mine productions, but also the necessary experience for creation of larger diameters BCs is obtained.
{"title":"Estimation of the Load Carrying Capacity of the Bellows Compensator for Gas Pipelines in the Areas of Mining Production","authors":"V. Stryzhalo, M. Zarazovskii, A. Bohdan, Z. Yaskovets, V. Antonchenko","doi":"10.1115/pvp2020-21738","DOIUrl":"https://doi.org/10.1115/pvp2020-21738","url":null,"abstract":"\u0000 The stress state of pipelines in areas of mine production requires obligatory consideration the influence of ground displacements. In this case the rules for design pipelines include the additional actions, such as the wall thickness increasing or U-shaped compensators installation.\u0000 The Ukrainian coal mining industry requires the expanding of mine production areas. It leads to the situation where old pipelines, which are not designed for such loads, could rupture due to ground displacements. The principle of “extinguish a fire” is applied in this case. It consists in applying of stress reduction actions before certain stage of mine production (so-called lava), such as digging out long sections, cutting and sanding, which require the involvement of significant human and material resources. But, in some cases, even the large-scale application of these actions does not lead to the stress reduction to the acceptable level (especially for pipelines of diameter less then 200mm). So, to solve this problem the implementation of bellow compensators (BC) is proposed.\u0000 The present work consists of:\u0000 • experimental investigations of BC which are carried out in order to obtain its bearing capacity and to validate its designed parameters guaranteed by the manufacturer;\u0000 • simulation of the BC loading process using FEM with adjusting the way of contact modelling between the BC layers in such manner, to be best correlate with the results of experiments;\u0000 • the application of obtained results for modelling of stress state of real pipelines in the areas of coal mine production.\u0000 The results of experimental investigation of BC of DN100 is presented. Their include: hydrotest with axial displacements limitation; tension-compression cycles for different values of amplitude with simultaneously loading of the operating value of gas pipeline internal pressure; rupture pressure determination.\u0000 Based on the experimental results, numerical modelling and specified domestic software for stress state assessment in pipelines the optimal locations and the required number of BCs is determined for buried gas pipelines. The results of presented works allowed us not only to implement the BCs to gas pipelines DN100 in areas of mine productions, but also the necessary experience for creation of larger diameters BCs is obtained.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129692458","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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