In this study, the mechanical behavior of Austenitic stainless steel 304L under low cycle fatigue was investigated under different uniaxial strain-controlled loadings of 0.5%, 0.8%, 1.0%, 1,2% and 1.5%. The analysis of the experimentally determined strain vs stress hysteresis curves were carried out to achieve stress quantities such as amplitude stress, peak effective stress, and peak back stress. It was observed that in the early stage of cyclic loading, material underwent initial hardening, followed by softening phenomena which were more considerable in the lower strain range. Before the failure, the secondary hardening was observed at the final stage. In addition to accumulated plastic strain, it was shown that the peak back stress and peak effective stress which is associated with isotropic hardening and kinematic hardening behavior, respectively, are influenced by the strain range effect. Therefore, the coefficient of recall term that appeared in the Armstrong_Frederick nonlinear kinematic hardening model was considered to be dependent on the radius of the memory surface. Furthermore, to increase the ability of the plasticity constitutive model to show a smooth transition between various hardening stages, the radius of the yield surface which is associated with the isotropic hardening rule was equipped with the fading effect. Finally, by the comparison of numerical and experimental results, the capability of the rate-dependent constitutive model over classical rate-independent plasticity in the prediction of mechanical behavior of steel 304L under strain-controlled cyclic loading was revealed.
{"title":"Experimental Analysis and Constitutive Modeling of Cyclic Behavior of 304L Stainless Steel: Introduction of Isotropic Hardening Fading Effect","authors":"Morteza Rajaeian, M. Parsa","doi":"10.1115/1.4056085","DOIUrl":"https://doi.org/10.1115/1.4056085","url":null,"abstract":"\u0000 In this study, the mechanical behavior of Austenitic stainless steel 304L under low cycle fatigue was investigated under different uniaxial strain-controlled loadings of 0.5%, 0.8%, 1.0%, 1,2% and 1.5%. The analysis of the experimentally determined strain vs stress hysteresis curves were carried out to achieve stress quantities such as amplitude stress, peak effective stress, and peak back stress. It was observed that in the early stage of cyclic loading, material underwent initial hardening, followed by softening phenomena which were more considerable in the lower strain range. Before the failure, the secondary hardening was observed at the final stage. In addition to accumulated plastic strain, it was shown that the peak back stress and peak effective stress which is associated with isotropic hardening and kinematic hardening behavior, respectively, are influenced by the strain range effect. Therefore, the coefficient of recall term that appeared in the Armstrong_Frederick nonlinear kinematic hardening model was considered to be dependent on the radius of the memory surface. Furthermore, to increase the ability of the plasticity constitutive model to show a smooth transition between various hardening stages, the radius of the yield surface which is associated with the isotropic hardening rule was equipped with the fading effect. Finally, by the comparison of numerical and experimental results, the capability of the rate-dependent constitutive model over classical rate-independent plasticity in the prediction of mechanical behavior of steel 304L under strain-controlled cyclic loading was revealed.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46349836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper reports the optimal use of control zones to achieve required uniformity of temperature distribution in local post weld heat treatment of welds in 9% Cr heat-resistant large pipe system. In this research, local PWHT tests on temperature distribution with different control zones were carried out on 9%Cr steel pipes (OD710 mm × 35 mm and OD575 mm × 35 mm), which was further used for the development of the thermal analysis of the post weld heat treatment model via ABAQUS. The research results revealed:1) the effect of number of control zone on the uniformity of temperature distribution;2) the effect of size of pipe diameter on the circumferential temperature and the through-thickness temperature gradients. This article discusses the possible reasons for the temperature difference at various positions of the pipe caused by the air flow inside the pipe with different control zones. Based on the obtained results, a practical method was designed for the selection the number of circumferential control zones on 9%Cr heat-resistant steel pipeline according to the required degree of temperature distribution uniformity. This paper contributes to the specific knowledge and the generic methodology.
{"title":"Optimization of Temperature Field by Differentiating Number of Circumferential Control Zones in Local Post Weld Heat Treatment on 9%Cr Heat-Resistant Steel Pipe","authors":"Xue Wang, Da Zhang, Fan Zhou, Qiang Xu","doi":"10.1115/1.4055524","DOIUrl":"https://doi.org/10.1115/1.4055524","url":null,"abstract":"\u0000 This paper reports the optimal use of control zones to achieve required uniformity of temperature distribution in local post weld heat treatment of welds in 9% Cr heat-resistant large pipe system. In this research, local PWHT tests on temperature distribution with different control zones were carried out on 9%Cr steel pipes (OD710 mm × 35 mm and OD575 mm × 35 mm), which was further used for the development of the thermal analysis of the post weld heat treatment model via ABAQUS. The research results revealed:1) the effect of number of control zone on the uniformity of temperature distribution;2) the effect of size of pipe diameter on the circumferential temperature and the through-thickness temperature gradients. This article discusses the possible reasons for the temperature difference at various positions of the pipe caused by the air flow inside the pipe with different control zones. Based on the obtained results, a practical method was designed for the selection the number of circumferential control zones on 9%Cr heat-resistant steel pipeline according to the required degree of temperature distribution uniformity. This paper contributes to the specific knowledge and the generic methodology.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46678160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Use of corrosion resistant cladding can greatly extend the design life of structural components in many advanced reactor systems. However, there are currently no ASME design rules for cladded components to guard against creep-fatigue failure and ratcheting strain accumulation in elevated temperature nuclear service. This paper, presented in two parts, addresses this gap by proposing a design strategy for cladded components that does not require long-term testing of clad materials. The proposed approach relies on approximate design analysis methods for two types of clad materials - a soft clad that creeps much faster than and has a lower yield stress than the Class A base material and a hard clad that creeps much slower than and has a higher yield stress than the Class A base material. This Part 1 discusses the approximate analysis strategies for the clad materials - treat a soft clad as perfectly compliant and a hard clad as linear elastic - and Part 2 develops a complete set of design rules for each of the two types of cladded components. Finite element analyses of representative high temperature reactor components show that the proposed design analysis methods can bound the design quantities in soft cladded components and approximate the design quantities in hard cladded components.
{"title":"Designing Cladded Components for High Temperature Nuclear Service. Part-1: Analysis Methods","authors":"M. Messner, B. Barua, R. Jetter, T. Sham","doi":"10.1115/1.4055437","DOIUrl":"https://doi.org/10.1115/1.4055437","url":null,"abstract":"\u0000 Use of corrosion resistant cladding can greatly extend the design life of structural components in many advanced reactor systems. However, there are currently no ASME design rules for cladded components to guard against creep-fatigue failure and ratcheting strain accumulation in elevated temperature nuclear service. This paper, presented in two parts, addresses this gap by proposing a design strategy for cladded components that does not require long-term testing of clad materials. The proposed approach relies on approximate design analysis methods for two types of clad materials - a soft clad that creeps much faster than and has a lower yield stress than the Class A base material and a hard clad that creeps much slower than and has a higher yield stress than the Class A base material. This Part 1 discusses the approximate analysis strategies for the clad materials - treat a soft clad as perfectly compliant and a hard clad as linear elastic - and Part 2 develops a complete set of design rules for each of the two types of cladded components. Finite element analyses of representative high temperature reactor components show that the proposed design analysis methods can bound the design quantities in soft cladded components and approximate the design quantities in hard cladded components.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42982374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper deals with fluid-structure interaction analysis of an hexagonal rod enclosed in a narrow viscous gap. A new analytical solution for a 2D cylindrical case is derived and described. A numerical solution of 2D Navier-Stokes equations coupled with an harmonic structure model is applied to both cylindrical and prism geometries. The comparison between the numerical tool and the analytical solution is discussed and a method to apply the analytical solution to the hexagonal case is proposed. An original definition of the added mass and damping based on an energetic approach is provided avoiding the dependence from the geometry and the type of forcing (free or forced vibration). An experimental facility is provided accounting for an hexagonal prism vibrating within a 7 mm enclosure. Free vibration experiments in water allow assessing the added mass and added damping effect on the modal parameters. The fluid flow is affected by a 3D effect - named downstrokes flow - at the top and the base of the assembly because of free surface and stoky geometry. This produces a higher frequency than the 2D theoretical value given both by the analytical solution and the numerical simulation. A geometrybased correction factor is suggested to taken into account in the 2D numerical simulation the 3D effect. Velocity measured within the gap provides further insight on this phenomenon and agrees well with the prediction of the transposed cylindrical analytical model.
{"title":"Added Mass and Damping of an Hexagonal Rod Vibrating in Highly Confined Viscous Fluids","authors":"L. Sargentini, B. Cariteau","doi":"10.1115/1.4055438","DOIUrl":"https://doi.org/10.1115/1.4055438","url":null,"abstract":"\u0000 This paper deals with fluid-structure interaction analysis of an hexagonal rod enclosed in a narrow viscous gap.\u0000 A new analytical solution for a 2D cylindrical case is derived and described. A numerical solution of 2D Navier-Stokes equations coupled with an harmonic structure model is applied to both cylindrical and prism geometries. The comparison between the numerical tool and the analytical solution is discussed and a method to apply the analytical solution to the hexagonal case is proposed.\u0000 An original definition of the added mass and damping based on an energetic approach is provided avoiding the dependence from the geometry and the type of forcing (free or forced vibration).\u0000 An experimental facility is provided accounting for an hexagonal prism vibrating within a 7 mm enclosure. Free vibration experiments in water allow assessing the added mass and added damping effect on the modal parameters.\u0000 The fluid flow is affected by a 3D effect - named downstrokes flow - at the top and the base of the assembly because of free surface and stoky geometry. This produces a higher frequency than the 2D theoretical value given both by the analytical solution and the numerical simulation. A geometrybased correction factor is suggested to taken into account in the 2D numerical simulation the 3D effect.\u0000 Velocity measured within the gap provides further insight on this phenomenon and agrees well with the prediction of the transposed cylindrical analytical model.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47601809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper describes an optimization scheme for the J parameter calculation of cracks postulated in complex geometrical configurations such as elbow entries/exits and/or thickness transitions. The principle of this scheme comes from the RSE-M/5.4 appendix allowing the definition of a specific compendium for given configurations. After a detailed presentation of the numerical protocol, an illustration of the required effort and the potential benefits is proposed for an elbow configuration. It is then shown that the effort is significant but can be anticipated and automated, but the potential benefit in terms of applied J significant (a ratio of three in the proposed application).
{"title":"Optimized J Evaluation Scheme for the Fracture Mechanics Assessment of Complex Piping Systems Subjected to Various Loading Sets","authors":"S. Chapuliot, S. Marie","doi":"10.1115/1.4055436","DOIUrl":"https://doi.org/10.1115/1.4055436","url":null,"abstract":"\u0000 This paper describes an optimization scheme for the J parameter calculation of cracks postulated in complex geometrical configurations such as elbow entries/exits and/or thickness transitions. The principle of this scheme comes from the RSE-M/5.4 appendix allowing the definition of a specific compendium for given configurations.\u0000 After a detailed presentation of the numerical protocol, an illustration of the required effort and the potential benefits is proposed for an elbow configuration. It is then shown that the effort is significant but can be anticipated and automated, but the potential benefit in terms of applied J significant (a ratio of three in the proposed application).","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43317721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, the water hammer pressure due to the sudden closure of the partially-open valve was investigated experimentally and analytically. Because the partially-open valve could produce local non-uniform flow, a supplementary Joukowsky's water hammer equation was derived based on the assumption of the local non-uniform flow and the kinetic energy equation. A physical model was set up to measure the maximum water hammer pressure of the first positive wave due to the sudden closure of partially-open valve under different conditions, including different water heads, flow velocities, pipe diameters and valve types. The results showed that Joukowsky's equation obtained by the momentum theorem in the uniform flow field was applicable to the uniform flow field with the valve fully open. The experimental results of the partially-open valve-closure water hammer pressure were 3.5%~21% larger than Joukowsky's equation, which consisted with the theoretical analysis of the supplementary Joukowsky's water hammer equation. This phenomenon had repeatability and was unrelated with the water head, the inlet flow velocity, the pipe diameter and the valve type. This study could provide guidance for water hammer protection in hydropower stations and pump stations.
{"title":"Analysis of Anomalies in Water-Hammer Experiments with Partially-Open Valves","authors":"Tingyu Xu, Lei Zhang, Weixiang Ni, Xiaoying Zhang, Xiao-dong Yu, Jian Zhang","doi":"10.1115/1.4055380","DOIUrl":"https://doi.org/10.1115/1.4055380","url":null,"abstract":"\u0000 In this study, the water hammer pressure due to the sudden closure of the partially-open valve was investigated experimentally and analytically. Because the partially-open valve could produce local non-uniform flow, a supplementary Joukowsky's water hammer equation was derived based on the assumption of the local non-uniform flow and the kinetic energy equation. A physical model was set up to measure the maximum water hammer pressure of the first positive wave due to the sudden closure of partially-open valve under different conditions, including different water heads, flow velocities, pipe diameters and valve types. The results showed that Joukowsky's equation obtained by the momentum theorem in the uniform flow field was applicable to the uniform flow field with the valve fully open. The experimental results of the partially-open valve-closure water hammer pressure were 3.5%~21% larger than Joukowsky's equation, which consisted with the theoretical analysis of the supplementary Joukowsky's water hammer equation. This phenomenon had repeatability and was unrelated with the water head, the inlet flow velocity, the pipe diameter and the valve type. This study could provide guidance for water hammer protection in hydropower stations and pump stations.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46620702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this review paper, dissimilar welding between Inconel and austenitic stainless steel along with its application has been outlined for high-temperature applications. The mechanical and microstructural behavior of this dissimilar joint has been summarized thoroughly in this article. Dissimilar welding of Inconel alloys and stainless steel (SS) has massive demand in high temperature and high corrosive applications industries. Austenitic stainless steel contains 16-26% of Cr and 6-12% of Ni elements showing FCC structures have good weldability and high corrosion resistance. Austenitic stainless steel such as 304, 316l, 304H, etc., containing austenite microstructure used in high-temperature applications like power plants, heat exchangers, heating elements, aircraft, and others. In addition, Ni-based Inconel alloys show high-temperature strength and corrosion resistance and are frequently used in high-temperature applications. Ni-based Inconel 718 alloy possesses excellent strength, corrosion resistance and creep resistance at high temperatures are frequently used in combustion chambers, power plants and turbine blades ap/plications. Inconel alloyed by elements Ti, Al and Nb attain strength by forming phases such as ?/-Ni3(-Ti, Al), ?//-Ni3Nb, and carbides such as MC and M23C6, nitrides, laves phase. The GTA dissimilar welding between expensive Inconel and cheaper stainless steel is successfully used in nuclear power plants. The dissimilarity in melting point, chemical composition, thermal, mechanical, and other properties between these materials make welding challengeable. This review paper focused on problems related to dissimilar welding like forming unmixed zone, elemental segregation, formation of laves phase, sensitization, microfissuring, and solidification cracking.
{"title":"Dissimilar Welding of Inconel Alloys with Austenitic Stainless-Steel: A Review","authors":"N. Kumar, C. Pandey, P. kumar","doi":"10.1115/1.4055329","DOIUrl":"https://doi.org/10.1115/1.4055329","url":null,"abstract":"\u0000 In this review paper, dissimilar welding between Inconel and austenitic stainless steel along with its application has been outlined for high-temperature applications. The mechanical and microstructural behavior of this dissimilar joint has been summarized thoroughly in this article. Dissimilar welding of Inconel alloys and stainless steel (SS) has massive demand in high temperature and high corrosive applications industries. Austenitic stainless steel contains 16-26% of Cr and 6-12% of Ni elements showing FCC structures have good weldability and high corrosion resistance. Austenitic stainless steel such as 304, 316l, 304H, etc., containing austenite microstructure used in high-temperature applications like power plants, heat exchangers, heating elements, aircraft, and others. In addition, Ni-based Inconel alloys show high-temperature strength and corrosion resistance and are frequently used in high-temperature applications. Ni-based Inconel 718 alloy possesses excellent strength, corrosion resistance and creep resistance at high temperatures are frequently used in combustion chambers, power plants and turbine blades ap/plications. Inconel alloyed by elements Ti, Al and Nb attain strength by forming phases such as ?/-Ni3(-Ti, Al), ?//-Ni3Nb, and carbides such as MC and M23C6, nitrides, laves phase. The GTA dissimilar welding between expensive Inconel and cheaper stainless steel is successfully used in nuclear power plants. The dissimilarity in melting point, chemical composition, thermal, mechanical, and other properties between these materials make welding challengeable. This review paper focused on problems related to dissimilar welding like forming unmixed zone, elemental segregation, formation of laves phase, sensitization, microfissuring, and solidification cracking.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44470923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Philippe A Gilles, Edith Marques Viera, O. Ancelet, P. Le Delliou, Thierry Le Grasse
Ductile fracture is characterized by large amount of deformation. Two mechanisms may lead to ductile failure: local tearing may appear in front of a stress concentration region like a crack front or large geometry changes in a weak part of the structure can lead to global collapse of the structure. For large cracks such as those considered in Leak Before Break studies, tearing analyses and net-section collapse criteria have been used. The present paper examines the link between these two mechanisms for a through-wall cracked pipe under bending and concludes that the transition from ductile tearing to collapse depends not only on material properties but also on geometrical parameters. The reference stress approach is a promising approach for predicting the transition, provided the transferability issue of J-Resistance curve has been solved.
{"title":"Ductile Tearing Or Plastic Collapse?","authors":"Philippe A Gilles, Edith Marques Viera, O. Ancelet, P. Le Delliou, Thierry Le Grasse","doi":"10.1115/1.4055259","DOIUrl":"https://doi.org/10.1115/1.4055259","url":null,"abstract":"\u0000 Ductile fracture is characterized by large amount of deformation. Two mechanisms may lead to ductile failure: local tearing may appear in front of a stress concentration region like a crack front or large geometry changes in a weak part of the structure can lead to global collapse of the structure. For large cracks such as those considered in Leak Before Break studies, tearing analyses and net-section collapse criteria have been used. The present paper examines the link between these two mechanisms for a through-wall cracked pipe under bending and concludes that the transition from ductile tearing to collapse depends not only on material properties but also on geometrical parameters. The reference stress approach is a promising approach for predicting the transition, provided the transferability issue of J-Resistance curve has been solved.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44017379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Deep-sea structures will collapse/implode under hydrostatic pressure when the structure dives below a threshold, leading to structural instability and catastrophic failure. To better understand how the layup angle of composite cylindrical shells influences this instability threshold, the present work explores how composite cylinders can achieve the highest (optimum) critical collapse pressure under hydrostatic loading conditions. To perform this analysis, a closed-form analytical cylinder buckling solution developed by previous work is used in conjunction with different cylindrical geometrical configurations and composite properties for glass, carbon, and intraply-hybrid composite properties for woven and unidirectional structures. The results show that a composite structure's optimum layup configuration is unique to the structure's geometry and material system. However, general trends are observed for these different systems, such as how symmetric and asymmetric constructions place the axial-resistant layers near the neutral plane of the composite system. In addition, both constructions need an increase in shear-resistance layers as the L/D ratio decreases regardless of the material system. Lastly, the analytical approach presented in this work can be used to accurately determine the optimum layup angle for composite cylindrical structures that are subjected to external hydrostatic pressure.
{"title":"Optimization of Composite Cylindrical Shell Structures for Hydrostatic Pressure Loading","authors":"H. Matos, Birendra Chaudhary, A. Ngwa","doi":"10.1115/1.4055159","DOIUrl":"https://doi.org/10.1115/1.4055159","url":null,"abstract":"\u0000 Deep-sea structures will collapse/implode under hydrostatic pressure when the structure dives below a threshold, leading to structural instability and catastrophic failure. To better understand how the layup angle of composite cylindrical shells influences this instability threshold, the present work explores how composite cylinders can achieve the highest (optimum) critical collapse pressure under hydrostatic loading conditions. To perform this analysis, a closed-form analytical cylinder buckling solution developed by previous work is used in conjunction with different cylindrical geometrical configurations and composite properties for glass, carbon, and intraply-hybrid composite properties for woven and unidirectional structures. The results show that a composite structure's optimum layup configuration is unique to the structure's geometry and material system. However, general trends are observed for these different systems, such as how symmetric and asymmetric constructions place the axial-resistant layers near the neutral plane of the composite system. In addition, both constructions need an increase in shear-resistance layers as the L/D ratio decreases regardless of the material system. Lastly, the analytical approach presented in this work can be used to accurately determine the optimum layup angle for composite cylindrical structures that are subjected to external hydrostatic pressure.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45177021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A method to determine lower and upper bound limit loads called interpolated moduli adjustment technique (IMAT) is proposed in this article. This method is based on iterative linear elastic analyses and is applied to several test cases of practical interest. IMAT fully conforms to the classical lower and upper bound theorems. In all the cases the upper and lower bound limit loads converge, thereby establishing the robustness of the technique. The results from IMAT correlate with non-linear finite element analysis consistently within 3%.
{"title":"Interpolated Moduli Adjustment Technique for Limit Loads","authors":"S. Mangalaramanan","doi":"10.1115/1.4055168","DOIUrl":"https://doi.org/10.1115/1.4055168","url":null,"abstract":"\u0000 A method to determine lower and upper bound limit loads called interpolated moduli adjustment technique (IMAT) is proposed in this article. This method is based on iterative linear elastic analyses and is applied to several test cases of practical interest. IMAT fully conforms to the classical lower and upper bound theorems. In all the cases the upper and lower bound limit loads converge, thereby establishing the robustness of the technique. The results from IMAT correlate with non-linear finite element analysis consistently within 3%.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49615176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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