Industries have shown interest in the use of dissimilar metals to make corrosion-resistant materials combined with good mechanical properties in marine environments. Explosive welding can be considered a good method for joining dissimilar materials to prevent galvanic corrosion. The aim of the present study was to simulate the non-linear behaviour of a Ti6Al4V/Inconel 625 welded joint obtained by explosion welding from the values of the tensile ultimate strength and yielding strength of the parent materials. The present study compared the stress-strain curve from tensile loading obtained by the non-linear finite element analysis with the experimental stress-strain curve of a bimetallic joint. The applied method provides useful information for the development of models and the prediction of the structural behaviour of Ti6Al4V/Inconel 625 explosive welded joints.
{"title":"Non-linear finite element analysis of a Ti6Al4V/Inconel 625 joint obtained by explosion welding for sub-sea applications","authors":"P. Corigliano","doi":"10.3723/UT.38.013","DOIUrl":"https://doi.org/10.3723/UT.38.013","url":null,"abstract":"Industries have shown interest in the use of dissimilar metals to make corrosion-resistant materials combined with good mechanical properties in marine environments. Explosive welding can be considered a good method for joining dissimilar materials to prevent galvanic corrosion. The\u0000 aim of the present study was to simulate the non-linear behaviour of a Ti6Al4V/Inconel 625 welded joint obtained by explosion welding from the values of the tensile ultimate strength and yielding strength of the parent materials. The present study compared the stress-strain curve from tensile\u0000 loading obtained by the non-linear finite element analysis with the experimental stress-strain curve of a bimetallic joint. The applied method provides useful information for the development of models and the prediction of the structural behaviour of Ti6Al4V/Inconel 625 explosive welded joints.","PeriodicalId":44271,"journal":{"name":"UNDERWATER TECHNOLOGY","volume":"53 1","pages":"13-16"},"PeriodicalIF":0.4,"publicationDate":"2021-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76660062","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}
Digital images are an excellent tool for divers to sample hard-bottom subtidal habitats as bottom time is limited and high-definition images can be collected quickly and accurately. The present paper describes a sampling protocol for benthic rocky reef communities using geo-referenced photoquadrats and tests the method over several rocky reefs of Atlantic Patagonia. This method was tested in two localities, separated by 100 km in a semi-enclosed gulf, covering a total of 5800 m of 11 rocky reefs using track roaming transects. The protocol is non-destructive, relatively low-cost and can adequately assess changes in marine habitats as rocky reefs. The implementation of artificial intelligence analysis using human expert training may reduce analysis time and increase the amount of data collected. The present study recommends this sampling methodology for programs aimed at monitoring changes in biodiversity.
{"title":"Monitoring rocky reef biodiversity by underwater geo-referenced photoquadrats","authors":"G. Bravo, J. Livore, G. Bigatti","doi":"10.3723/UT.38.017","DOIUrl":"https://doi.org/10.3723/UT.38.017","url":null,"abstract":"Digital images are an excellent tool for divers to sample hard-bottom subtidal habitats as bottom time is limited and high-definition images can be collected quickly and accurately. The present paper describes a sampling protocol for benthic rocky reef communities using geo-referenced\u0000 photoquadrats and tests the method over several rocky reefs of Atlantic Patagonia. This method was tested in two localities, separated by 100 km in a semi-enclosed gulf, covering a total of 5800 m of 11 rocky reefs using track roaming transects. The protocol is non-destructive, relatively\u0000 low-cost and can adequately assess changes in marine habitats as rocky reefs. The implementation of artificial intelligence analysis using human expert training may reduce analysis time and increase the amount of data collected. The present study recommends this sampling methodology for programs\u0000 aimed at monitoring changes in biodiversity.","PeriodicalId":44271,"journal":{"name":"UNDERWATER TECHNOLOGY","volume":"65 5 1","pages":"17-24"},"PeriodicalIF":0.4,"publicationDate":"2021-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89862298","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 insertion losses of five neoprene diving hoods of varying thicknesses (2 mm–9 mm) were measured in one-third octave bands using a Kemar manikin in a diffuse broadband noise field. The insertion losses were measured in air for both dry and wet hoods. The insertion loss was calculated as the sound level in each frequency band measured with the hood, minus the corresponding sound level measured without the hood. The insertion losses were similar for both ears of the manikin. Both wet and dry hoods neither attenuated nor amplified sound below 250 Hz. Between 315 Hz–1250 Hz, the insertion loss of each hood was negative, displaying a broad resonance with a gain of 6–8 dB. In this frequency range the hood acts as a mass-spring system, resonating like a drum skin when stretched over the ears. Above 1000 Hz, the insertion loss increased with frequency (10 dB per octave), reaching a maximum of 5000 Hz–6000 Hz. Wetting each hood did not significantly affect the insertion loss; the ‘drum-skin’ resonance frequency was marginally lower with a wet hood, and insertion losses may be marginally greater between 1000 Hz– 10 000 Hz. The resonance frequency decreased with increasing thicknesses of hood, and the insertion loss at frequencies above the resonance increased with hood thickness.
{"title":"Attenuation of airborne noise by wet and dry neoprene diving hoods","authors":"G. Paddan, M. Lower","doi":"10.3723/UT.38.003","DOIUrl":"https://doi.org/10.3723/UT.38.003","url":null,"abstract":"The insertion losses of five neoprene diving hoods of varying thicknesses (2 mm–9 mm) were measured in one-third octave bands using a Kemar manikin in a diffuse broadband noise field. The insertion losses were measured in air for both dry and wet hoods. The insertion loss was calculated as the sound level in each frequency band measured with the hood, minus the corresponding sound level measured without the hood. The insertion losses were similar for both ears of the manikin. Both wet and dry hoods neither attenuated nor amplified sound below 250 Hz. Between 315 Hz–1250 Hz, the insertion loss of each hood was negative, displaying a broad resonance with a gain of 6–8 dB. In this frequency range the hood acts as a mass-spring system, resonating like a drum skin when stretched over the ears. Above 1000 Hz, the insertion loss increased with frequency (10 dB per octave), reaching a maximum of 5000 Hz–6000 Hz. Wetting each hood did not significantly affect the insertion loss; the ‘drum-skin’ resonance frequency was marginally lower with a wet hood, and insertion losses may be marginally greater between 1000 Hz– 10 000 Hz. The resonance frequency decreased with increasing thicknesses of hood, and the insertion loss at frequencies above the resonance increased with hood thickness.","PeriodicalId":44271,"journal":{"name":"UNDERWATER TECHNOLOGY","volume":"1 1","pages":"3-12"},"PeriodicalIF":0.4,"publicationDate":"2021-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82993304","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}
Kang Yongtian, Xiao Wensheng, Zhang Dagang, Zhang Liang, Zhou Chouyao, Li Mingang
The deepwater cable bending restrictor is an important protective device for risers, umbilicals and cables in offshore engineering, protecting cable structure by controlling minimum bending radius. Its mechanical properties are analysed based on the numerical analysis model and finite element analysis (FEM) of ø175. The sensitivity analysis of using quantity of bending restrictors is also performed to show the effect of the quantity on bending stiffness. A testing scheme of bending stiffness of the bending restrictor is then formulated based on its structure. From numerical analysis results through test simulation, the tolerance is less than 3 %, which verifies the reliability of the numerical analysis model. Performance of the bending restrictor and dynamic response are analysed according to environmental parameters that occur once per 100 years from offshore wind power farms and pipein-pipe models, respectively. The results show the bending restrictor can effectively protect cable structure, and the pipein-pipe model is suitable for calculating mechanical properties of interaction between the bending restrictor and cable.
{"title":"Performance validation and dynamic response analysis of a deepwater cable bending restrictor","authors":"Kang Yongtian, Xiao Wensheng, Zhang Dagang, Zhang Liang, Zhou Chouyao, Li Mingang","doi":"10.3723/ut.37.095","DOIUrl":"https://doi.org/10.3723/ut.37.095","url":null,"abstract":"The deepwater cable bending restrictor is an important protective device for risers, umbilicals and cables in offshore engineering, protecting cable structure by controlling minimum bending radius. Its mechanical properties are analysed based on the numerical analysis model and finite\u0000 element analysis (FEM) of ø175. The sensitivity analysis of using quantity of bending restrictors is also performed to show the effect of the quantity on bending stiffness. A testing scheme of bending stiffness of the bending restrictor is then formulated based on its structure. From\u0000 numerical analysis results through test simulation, the tolerance is less than 3 %, which verifies the reliability of the numerical analysis model. Performance of the bending restrictor and dynamic response are analysed according to environmental parameters that occur once per 100 years from\u0000 offshore wind power farms and pipein-pipe models, respectively. The results show the bending restrictor can effectively protect cable structure, and the pipein-pipe model is suitable for calculating mechanical properties of interaction between the bending restrictor and cable.","PeriodicalId":44271,"journal":{"name":"UNDERWATER TECHNOLOGY","volume":"69 1","pages":"95-101"},"PeriodicalIF":0.4,"publicationDate":"2020-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72799335","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}
X. Ran, Z. Yu, Zheng Lijun, Zhang Zhou, Guo Jiang-yan
The umbilical is one of the most important components of a subsea production system. Processing errors and environmental load deviations may occur during the manufacturing process, and the deterministic design based on safety factors is often unable to meet the needs of engineering. In the present paper, the random distribution law of the umbilical geometry parameters is considered to analyse the reliability of the umbilical under the ultimate tensile load by combining the response surface approach of reliability analysis with the finite element analysis.
{"title":"Reliability analysis of an umbilical under ultimate tensile load based on response surface approach","authors":"X. Ran, Z. Yu, Zheng Lijun, Zhang Zhou, Guo Jiang-yan","doi":"10.3723/ut.37.087","DOIUrl":"https://doi.org/10.3723/ut.37.087","url":null,"abstract":"The umbilical is one of the most important components of a subsea production system. Processing errors and environmental load deviations may occur during the manufacturing process, and the deterministic design based on safety factors is often unable to meet the needs of engineering.\u0000 In the present paper, the random distribution law of the umbilical geometry parameters is considered to analyse the reliability of the umbilical under the ultimate tensile load by combining the response surface approach of reliability analysis with the finite element analysis.","PeriodicalId":44271,"journal":{"name":"UNDERWATER TECHNOLOGY","volume":"12 1","pages":"87-93"},"PeriodicalIF":0.4,"publicationDate":"2020-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82925740","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 order to master the microscopic growth mechanism of natural gas hydrate, a series of experiments were carried out using a high-pressure hydrate flow loop. The microscopic physical information of the growth of hydrates in the emulsion system is captured by advanced microscopic equipment and the phenomena of the experiments show that: 1) not all water droplets instantaneously generate a hydrate shell, but only a few of the water droplets gradually generate a hydrate shell when reaching the conditions of the hydrate formation; and 2) the coalescence and shear do occur in the hydrate formation process, and the distribution of hydrate particle size has changed.
{"title":"Study on microscopic growth mechanism of emulsion system hydrate","authors":"Jin Zhang, Ann S. Chen, Menglan Duan","doi":"10.3723/ut.37.071","DOIUrl":"https://doi.org/10.3723/ut.37.071","url":null,"abstract":"In order to master the microscopic growth mechanism of natural gas hydrate, a series of experiments were carried out using a high-pressure hydrate flow loop. The microscopic physical information of the growth of hydrates in the emulsion system is captured by advanced microscopic equipment\u0000 and the phenomena of the experiments show that: 1) not all water droplets instantaneously generate a hydrate shell, but only a few of the water droplets gradually generate a hydrate shell when reaching the conditions of the hydrate formation; and 2) the coalescence and shear do occur in the\u0000 hydrate formation process, and the distribution of hydrate particle size has changed.","PeriodicalId":44271,"journal":{"name":"UNDERWATER TECHNOLOGY","volume":"45 1","pages":"71-77"},"PeriodicalIF":0.4,"publicationDate":"2020-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87212755","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}
X. Zhen, Yue Han, Qiu-yang Duan, Wu Jiahao, Yi Huang
The present paper describes a new offshore field development solution, Next Generation Subsea Production System (NextGen SPS), that aims to overcome the technical and commercial limitations of the current offshore field development concepts (dry tree or subsea tree) in ultra-deep water (more than 1500 m). The key developments of the NextGen SPS, including its main characteristics, stability characteristics and optimal design on the riser system, are presented and discussed. The series of studies demonstrates that the NextGen SPS offers improved technical and commercial performance, higher levels of safety, reduced interface complexity and improved development flexibility for field development in ultra-deep water.
{"title":"Development of next generation subsea production system (NextGen SPS) design and analysis for ultra-deepwater applications","authors":"X. Zhen, Yue Han, Qiu-yang Duan, Wu Jiahao, Yi Huang","doi":"10.3723/ut.37.111","DOIUrl":"https://doi.org/10.3723/ut.37.111","url":null,"abstract":"The present paper describes a new offshore field development solution, Next Generation Subsea Production System (NextGen SPS), that aims to overcome the technical and commercial limitations of the current offshore field development concepts (dry tree or subsea tree) in ultra-deep water\u0000 (more than 1500 m). The key developments of the NextGen SPS, including its main characteristics, stability characteristics and optimal design on the riser system, are presented and discussed. The series of studies demonstrates that the NextGen SPS offers improved technical and commercial performance,\u0000 higher levels of safety, reduced interface complexity and improved development flexibility for field development in ultra-deep water.","PeriodicalId":44271,"journal":{"name":"UNDERWATER TECHNOLOGY","volume":"1 1","pages":"111-117"},"PeriodicalIF":0.4,"publicationDate":"2020-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89806276","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}
Zhang Jiayu, Junpeng Liu, Kexuan Duan, Li Wenbo, Duan Menglan
The creep behaviour of an inner liner, one of the reasons for carcass tearing, may affect the structural integrity of flexible risers. This has been previously discussed without conclusive results owing to complex structure and time-dependent material properties. The present paper proposes a numerical model for predicting creep responses by means of the finite element method. In this model, series coefficient is used to characterise the viscoelastic properties of material. Consequently, the influence of geometric parameters such as span of the carcass layer and thickness of the inner layer on the deformation is observed. Moreover, a threedimensional model assembling the carcass and inner liner was established for mechanical analysis, during which the viscoelasticity of inner liner and the internal friction of the carcass are considered, after which the stress and strain distribution on each layer under the combined external pressure and axial tensile force generated by the inner liner are obtained. Additionally, the effect of external pressures on the stress distribution of the carcass cross-section was found through sensitivity analysis.
{"title":"Numerical simulation of creep behaviour of flexible riser inner liner","authors":"Zhang Jiayu, Junpeng Liu, Kexuan Duan, Li Wenbo, Duan Menglan","doi":"10.3723/ut.37.079","DOIUrl":"https://doi.org/10.3723/ut.37.079","url":null,"abstract":"The creep behaviour of an inner liner, one of the reasons for carcass tearing, may affect the structural integrity of flexible risers. This has been previously discussed without conclusive results owing to complex structure and time-dependent material properties. The present paper proposes\u0000 a numerical model for predicting creep responses by means of the finite element method. In this model, series coefficient is used to characterise the viscoelastic properties of material. Consequently, the influence of geometric parameters such as span of the carcass layer and thickness of\u0000 the inner layer on the deformation is observed. Moreover, a threedimensional model assembling the carcass and inner liner was established for mechanical analysis, during which the viscoelasticity of inner liner and the internal friction of the carcass are considered, after which the stress\u0000 and strain distribution on each layer under the combined external pressure and axial tensile force generated by the inner liner are obtained. Additionally, the effect of external pressures on the stress distribution of the carcass cross-section was found through sensitivity analysis.","PeriodicalId":44271,"journal":{"name":"UNDERWATER TECHNOLOGY","volume":"104 1","pages":"79-86"},"PeriodicalIF":0.4,"publicationDate":"2020-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77344762","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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