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Kunpeng Wang - One of the best experts on this subject based on the ideXlab platform.
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fatigue sensitivity analysis of Steel Catenary Riser near touchdown point
Journal of Shanghai Jiaotong University (science), 2017Co-Authors: Kunpeng Wang, Chunyan Ji, Wenyong TangAbstract:By transforming the platform response obtained from coupled hydrodynamic analysis to the top motions of Steel Catenary Riser (SCR), the nonlinear dynamic analysis of the SCR is carried out in Abaqus/Aqua. In this analysis, the SCR-seabed interaction is well taken into account by introducing the seabed trench model and hysteretic seabed model. The fatigue damage of the SCR near touchdown point (TDP) is calculated using rain-flow counting methodology, and the sensitivity of the fatigue damage to the seabed and wave parameters are investigated. The results indicate that as seabed stiffness increases, the fatigue life and its sensitivity to seabed stiffness decrease. Seabed trenching may benefit the fatigue life of the SCR and the trench position should be elaborated for realistic fatigue damage prediction. Due to the induced platform response, significant wave height and spectral peak period have significant effects on the fatigue damage, thus the short-term sea state bins should be carefully selected from the wave scatter diagram.
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study of seabed trench induced by Steel Catenary Riser and seabed interaction
ASME 2016 35th International Conference on Ocean Offshore and Arctic Engineering, 2016Co-Authors: Kunpeng WangAbstract:Seabed trench profile has significant effect on the fatigue damage of Steel Catenary Riser near touchdown point. This study briefly demonstrates an approach in literature to determine the seabed trench induced by wave frequency response based on the cubic polynomial model. In this approach, a criterion for the matching between Catenary Riser and seabed trench is proposed, which is an optimization problem, and needs iterative static analysis of Catenary Riser. Based on the criterion, the sensitivity of the trench length and position to three parameters is parametrically studied: Riser mass per unit length, ratio of horizontal span to vertical span of Catenary part, trench depth. The obtained data are employed to fit the equations of trench length and position, which is taken as surrogate model since the iterative static analysis is very complicated. For completeness, the validation against data obtained from hysteretic seabed model is also illustrated. Based on the surrogate model, this study investigates the effect of trench depth on the fatigue damage near touchdown and the effect of the low frequency response on the seabed trench, and some useful conclusions are obtained.Copyright © 2016 by ASME
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a simple parametric formulation for the seabed trench profile beneath a Steel Catenary Riser
Marine Structures, 2016Co-Authors: Kunpeng Wang, Ying Min LowAbstract:Abstract Seabed trench has a profound influence on the fatigue performance of a Steel Catenary Riser (SCR) at the touchdown zone. At present, the most well-regarded approach for simulating the complex trench development process is by applying a nonlinear hysteresis seabed contact model, which is time consuming. Field observations have indicated that the trench depth almost stabilizes after a few months following installation. Hence, for practical fatigue design, it is expedient to specify an initial static trench profile to perform the dynamic simulations. This paper presents a new simple parametric formulation for delineating an initial trench profile, as there appears to be no such approach in the literature. The formulation entails two unknown trench parameters (trench length and global trench position), which can be determined using a new iterative static analysis method proposed herein. However, the analysis involves solving a constrained optimization problem, and is not ideal for practical applications. Thus, a surrogate model is devised, by approximating the trench parameters as multivariate polynomial functions of three dimensionless variables of the SCR. A case study comparing the trenches obtained from seabed contact model, static analysis, and surrogate model, shows that the different trench profiles and the associated maximum fatigue damage are in close agreement.
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time domain approach for coupled cross flow and in line viv induced fatigue damage of Steel Catenary Riser at touchdown zone
Marine Structures, 2015Co-Authors: Kunpeng Wang, Wenyong Tang, Hongxiang XueAbstract:Abstract Existing VIV prediction approaches for Steel Catenary Riser (SCR) typically employ truncation model without considering the interaction between the SCR and soil, and only allow for cross-flow (CF) VIV. In this study, a time domain approach accounting for the SCR-soil interaction is proposed to predict the CF and in-line (IL) VIV induced fatigue damage of a SCR at touchdown zone (TDZ). The hydrodynamic force resulting from the vortex shedding is modeled using the forced oscillation test data of a rigid cylinder and an empirical damping model, which are defined as functions of the non-dimensional dominant frequency and amplitude of the SCR response. Due to the coupling effect, the IL VIV force is magnified based on the CF VIV amplitude. By combining a linear hysteretic interaction model with a trench shape model, some particular phenomena during the vertical SCR-soil interaction are captured and qualitatively discussed, while for the horizontal direction, the seabed is simplified as nonlinear spring model. Based on these models, parametric studies are conducted to broaden the understanding of the sensitivity of VIV induced fatigue damage to the seabed characteristic. The results indicate trench depth, vertical and lateral stiffness, and clay suction are significantly affect the VIV induced maximum fatigue damage at TDZ.
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Cross-flow VIV-induced fatigue damage of deepwater Steel Catenary Riser at touch-down point
China Ocean Engineering, 2014Co-Authors: Kunpeng Wang, Wenyong Tang, Hongxiang XueAbstract:A prediction model of the deepwater Steel Catenary Riser VIV is proposed based on the forced oscillation test data, taking into account the Riser-seafloor interaction for the cross-flow VIV-induced fatigue damage at touch-down point (TDP). The model will give more reasonable simulation of SCR response near TDP than the previous pinned truncation model. In the present model, the hysteretic Riser-soil interaction model is simplified as the linear spring and damper to simulate the seafloor, and the damping is obtained according to the dissipative power during one periodic Riser-soil interaction. In order to validate the model, the comparison with the field measurement and the results predicted by Shear 7 program of a full-scale Steel Catenary Riser is carried out. The main induced modes, mode frequencies and response amplitude are in a good agreement. Furthermore, the parametric studies are carried out to broaden the understanding of the fatigue damage sensitivity to the upper end in-plane offset and seabed characteristics. In addition, the fatigue stress comparison at TDP between the truncation Riser model and the present full Riser model shows that the existence of touch-down zones is very important for the fatigue damage assessment of Steel Catenary Riser at TDP.
Hezhen Yang - One of the best experts on this subject based on the ideXlab platform.
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Hill Stability Prediction of Deep-Sea Steel Catenary Riser
Journal of Shanghai Jiaotong University, 2014Co-Authors: F. Xiao, Hezhen YangAbstract:Hill stability of deep-sea Steel Catenary Riser (SCR) was predicted based on bi-frequency excitation. The SCR was transferred into top tensioned Riser (TTR) based on Vandiver theory, the multi-frequency signal is proposed to simulate the stochastic tension fluctuation, and Hill equation was obtained according to the dynamic motion equation of TTR under multi-frequency excitation. The parametric stability characteristic of the SCR system under bi-frequency excitation, a typical case of multi-frequency, was primarily discussed, and bi-frequency excitation was used for practical engineering analysis. The results show that multi-frequency excitation can better predict real sea condition than single frequency, the prediction of real external excitation is vital to the parametric stability prediction of SCR, and the Riser safety design requirements are determined by the corresponding form of excitation function chosen.
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dynamic and fatigue analyses of stress joint for deepwater Steel Catenary Riser
ASME 2012 31st International Conference on Ocean Offshore and Arctic Engineering, 2012Co-Authors: Hezhen Yang, Wenqing ZhengAbstract:As the offshore industry continues to progress developments in deepwater, Steel Catenary Riser (SCR) offers great advantages over other Risers. In order to provide the hang-off with sufficient stiffness, stress joint is used to connect the Riser with platform. When stress joints are located at the top of a deep marine Riser, it is greatly affected by both axial and bending stress due to great cyclic loading. So it is necessary to do some research on dynamic and local fatigue analyses for stress joint.In this work, global dynamic analysis for a SCR is performed firstly, then local boundary condition obtained from the previous analysis are applied to the stress joint FE model for time domain dynamic and multiaxial fatigue analysis. Results indicate that the stress level is far lower than yield limit of material and damage induced by fatigue needs more attention. Besides, the damage character of the two types of stress joints differs: for TSJ, the place where stress joint connects with Riser is easy to occur fatigue damage; for SSJ, the most probable position is at the place where the end of inner sleeve pipe contacts with the Riser body. Compared with SSJ, TSJ shows a higher stress level but better fatigue performance, and it will have a higher material cost. Considering various factors, designers should choose the most suitable type and also geometric parameters.Copyright © 2012 by ASME
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optimization design for Steel Catenary Riser with fatigue constraints
International Journal of Offshore and Polar Engineering, 2011Co-Authors: Hezhen Yang, Huajun Li, Hanil ParkAbstract:This paper presents an efficient optimization strategy for deepwater Risers' design under fatigue life constraints. The Steel Catenary Risers (SCR) concept has been considered to be a vital option for most new deepwater field developments around the world. The deepwater Riser design is characterized by the consideration of numerous load cases, geometric nonlinearity and highly responsive dynamic nature of the system. It is very computationally expensive for the optimization process. Moreover, very little research has been conducted to incorporate the fatigue constraints into SCR optimization design. As water depths increase further, the large vertical motion at the semi or FPSO induces severe Riser response, which results in difficulty meeting strength and fatigue criteria at the hangoff and touchdown point locations. This work analyzes the use of an Island-based Genetic Algorithm (IGA) to minimize the Riser cost while keeping all constraints satisfied. A Kriging method in conjunction with design of experiments is used to construct an approximation model for dynamic and fatigue analysis. The geometric size and density of the coating types for SCR are varied so as to determine an optimum configuration. It demonstrates the effectiveness of this optimization strategy by integrating the approximation model into the design process considering fatigue life constraints.
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multiaxial fatigue analysis of the stress joint for a deepwater Steel Catenary Riser
Journal of Harbin Engineering University, 2011Co-Authors: W Zheng, Hezhen YangAbstract:The object of this paper is to present a more accurate and useful method for fatigue analysis and life prediction for a stress joint of a deepwater Steel Catenary Riser. The stress joint was used to connect the Riser and platform, and it was subjected to ocean environmental loadings and erosion; thus, the fatigue problem is critical. First, global time domain dynamic analysis of the Steel Catenary Riser was performed, and then local analysis was performed for the stress joint. Finally, the fatigue life of the stress joint was evaluated according to the multiaxial fatigue theory, and a preliminary parametric study was also carried out. Results show that taking stress value of the structure as the only criterion is not enough, and fatigue analysis is necessary when the structure is subjected to an alternating load. Compared with uniaxial analysis, multiaxial fatigue analysis can reflect the damage of the structure more realistically. Especially for deepwater Steel Catenary Risers, multiaxial fatigue problems should be given close attention.
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metamodel approach for reliability based design optimization of a Steel Catenary Riser
Journal of Marine Science and Technology, 2011Co-Authors: Hezhen Yang, Wenqing ZhengAbstract:A reliability-based design optimization (RBDO) methodology is presented for the design of a Steel Catenary Riser (SCR) under dynamic environmental loads. The purpose of this work is to optimize the cost of products subjected to probabilistic constraints. Searching for the optimal design of the Riser in a wide range of design variables is computationally very expensive if time-consuming codes for dynamic analysis are necessary in the iteration process. In this study, the effectiveness of the proposed RBDO using a metamodel is firstly studied and validated through a beam test, then applied to the industrial dynamic optimization problem. The design variables of structures are assumed to be uncertain, and some other parameters such as loading and material properties are considered random. The performance function is approximated using metamodels to avoid time-consuming finite-element analysis during the optimization iteration. A single-loop method is used to decouple the double-loop RBDO problem. The reliability is finally confirmed through Monte Carlo simulations. According to the analysis, the presented methodology is more rational and realistic compared with deterministic optimization.
Jungao Wang - One of the best experts on this subject based on the ideXlab platform.
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An experiment study of vortex induced vibration of a Steel Catenary Riser under steady current
Journal of Hydrodynamics, 2020Co-Authors: Tie Ren, Jungao Wang, Haojie Ren, Mengmeng Zhang, Yao-song ChenAbstract:The vortex induced vibration (VIV) of marine Risers has been investigated by many researchers in experimental studies of a straight flexible Riser model as well as a rigid cylinder to reveal the dynamic response characteristic and the mechanics behind it. However, due to the limitation of experimental apparatus, very few studies are about the VIV of a Steel Catenary Riser (SCR) which is with a complex geometry. To investigate the VIV features and to further develop the corresponding numerical predictions of a SCR under steady current, a large-scale model test of a SCR was towed in an ocean basin at various speeds. Fiber Bragg grating strain sensors are instrumented on the Riser model to measure both in-plane and out-of-plane responses. The characteristics of oscillating amplitude and dominating frequency response, the phenomenon of mode competition and travelling wave and the fatigue damage of the Steel Catenary Riser in inline and cross-flow direction under steady current are analyzed.
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Vortex Induced Vibration of a Steel Catenary Riser Under Out-of-Plane Current: An Experimental Study
Volume 2: CFD and FSI, 2019Co-Authors: Jungao Wang, Haojie Ren, Mengmeng ZhangAbstract:Abstract To investigate the VIV characteristics and to further develop the corresponding numerical predictions of a Steel Catenary Riser under out-of-plane current, a large-scale model of a Steel Catenary Riser was towing in an ocean basin at various speeds and directions. Fiber Bragg grating strain sensors are instrumented on the Riser model to measure both in-plane and out-of-plane responses. The vortex-induced vibration responses of the Steel Catenary Riser under out-of-plane current, i.e., the oscillating amplitude, the response frequency, and the traveling wave phenomenon, are compared with those under the in-plane current.
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evaluation of vortex induced vibration of a Steel Catenary Riser in steady current and vessel motion induced oscillatory current
Journal of Fluids and Structures, 2018Co-Authors: Shixiao Fu, Jungao Wang, Rolf BaarholmAbstract:Abstract A large-scale model test of a truncated Steel Catenary Riser (SCR) was performed in an ocean basin to investigate the Riser responses under pure steady uniform current and pure vessel motions separately. Out-of-plane vortex-induced vibration (VIV) was confirmed to have occurred under both test conditions. A comparative analysis and discussion were carried out on selected cases in terms of out-of-plane VIV responses, VIV developing mechanisms and the fatigue damage contribution. Results indicate that both steady current-induced and vessel motion-induced VIV responses are dominated by strong travelling waves, but vessel motion-induced VIV responses are more ‘intermittent’ with respect to the response amplitude and frequency owing to its space- and time-varying shedding frequency. ‘Power-in’ regions are further estimated to understand the VIV developing mechanisms for both test conditions. Finally, fatigue damages are evaluated showing the damage by vessel motion-induced VIV is comparable and at the same level as uniform current-induced VIV, which highlights the great importance of vessel motion-induced VIV, which cannot be neglected in the design and analysis for SCR systems.
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Global motion reconstruction of a Steel Catenary Riser under vessel motion
Ships and Offshore Structures, 2018Co-Authors: Jungao Wang, Rolf Baarholm, Mengmeng Zhang, Chang LiuAbstract:ABSTRACTUnder vessel motion, dynamic responses of compliant Risers, like a Steel Catenary Riser, are no longer small displacement and small deformation problems but characterised with large displacement and small deformation instead. It is therefore difficult to directly obtain the Riser global motion based on experimental or field-measured local strain or acceleration data. This paper proposes a generalised global motion reconstruction method for large displacement but small deformation problems, assuming that the global motion can be divided into quasi-static motion and dynamic vibration. The proposed methodology is validated numerically and experimentally with satisfactory accuracy. Parameters like sensor location and mode number to be used in the motion reconstruction are optimised and recommended. Uncertainty analysis considering different noise levels is performed to evaluate the robustness of the proposed method. Most importantly, further comparative hydrodynamic analyses indicate the significance ...
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out of plane vortex induced vibration of a Steel Catenary Riser caused by vessel motions
Ocean Engineering, 2015Co-Authors: Jungao Wang, Shixiao Fu, Rolf Baarholm, Jie Wu, Carl M LarsenAbstract:A large-scale model test of a truncated Steel Catenary Riser (SCR) was performed in an ocean basin to investigate the Riser responses under top vessel motion. Top end of the model was forced to oscillate at given motion trajectories, corresponded with the motion at the truncation point of a full-length SCR under vessel motion. Out-of-plane vortex-induced vibration (VIV) was confirmed under pure top vessel motions, characterized with distinctive time-varying features. Results further indicate that vessel motion-induced VIV was strongly dependent on the KC number and the instantaneous equivalent flow profile. Meanwhile, tension variation was found to be another key factor causing response discrepancy between the ‘lift-up’ and ‘push-down’ phase for the large top vessel motion case. Finally, the relationship between the out-of-plane VIV dominant response frequency, maximum equivalent flow velocity and KC number were unveiled, which provides references for future vessel motion-induced VIV predictions.
Wenyong Tang - One of the best experts on this subject based on the ideXlab platform.
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nonlinear Riser seabed interaction response among touchdown zone of a Steel Catenary Riser in consideration of vortex induced vibration
Ocean Engineering, 2021Co-Authors: Yuchao Yuan, Hongxiang Xue, Mengtian Zheng, Wenyong TangAbstract:Abstract Steel Catenary Riser (SCR) is a preferred solution for deepwater oil and gas exploitation under harsh marine environment. Its Riser-seabed interaction (RSI) among touchdown zone (TDZ) in consideration of the vortex-induced vibration (VIV) of sag bend is at present a research frontier in ocean engineering. This paper integrates Randolph-Quiggin model into a published global numerical Riser model, to investigate the nonlinear RSI response among TDZ of an SCR with VIV. The adopted numerical model is validated against some published experimental measurements for VIV and RSI respectively. Three combined cases with top-end platform heave motion and VIV are simulated, and the trench development as well as the SCR's response characteristics among TDZ is analyzed. VIV makes the trench develop more smoothly, and the trench length as well as depth turns smaller. The VIV effect on RSI is relatively significant with violent heave excitation, under which the P-z curves present clearer interaction mode transitions. VIV enlarges the maximum bending moment visibly, and makes the sag bend of SCR dominated by higher-order modes, which are both detrimental to the structural safety. The coupling effect between RSI and VIV on the Riser's dynamic response needs to be considered for the design of full-scale SCRs.
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fatigue sensitivity analysis of Steel Catenary Riser near touchdown point
Journal of Shanghai Jiaotong University (science), 2017Co-Authors: Kunpeng Wang, Chunyan Ji, Wenyong TangAbstract:By transforming the platform response obtained from coupled hydrodynamic analysis to the top motions of Steel Catenary Riser (SCR), the nonlinear dynamic analysis of the SCR is carried out in Abaqus/Aqua. In this analysis, the SCR-seabed interaction is well taken into account by introducing the seabed trench model and hysteretic seabed model. The fatigue damage of the SCR near touchdown point (TDP) is calculated using rain-flow counting methodology, and the sensitivity of the fatigue damage to the seabed and wave parameters are investigated. The results indicate that as seabed stiffness increases, the fatigue life and its sensitivity to seabed stiffness decrease. Seabed trenching may benefit the fatigue life of the SCR and the trench position should be elaborated for realistic fatigue damage prediction. Due to the induced platform response, significant wave height and spectral peak period have significant effects on the fatigue damage, thus the short-term sea state bins should be carefully selected from the wave scatter diagram.
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time domain approach for coupled cross flow and in line viv induced fatigue damage of Steel Catenary Riser at touchdown zone
Marine Structures, 2015Co-Authors: Kunpeng Wang, Wenyong Tang, Hongxiang XueAbstract:Abstract Existing VIV prediction approaches for Steel Catenary Riser (SCR) typically employ truncation model without considering the interaction between the SCR and soil, and only allow for cross-flow (CF) VIV. In this study, a time domain approach accounting for the SCR-soil interaction is proposed to predict the CF and in-line (IL) VIV induced fatigue damage of a SCR at touchdown zone (TDZ). The hydrodynamic force resulting from the vortex shedding is modeled using the forced oscillation test data of a rigid cylinder and an empirical damping model, which are defined as functions of the non-dimensional dominant frequency and amplitude of the SCR response. Due to the coupling effect, the IL VIV force is magnified based on the CF VIV amplitude. By combining a linear hysteretic interaction model with a trench shape model, some particular phenomena during the vertical SCR-soil interaction are captured and qualitatively discussed, while for the horizontal direction, the seabed is simplified as nonlinear spring model. Based on these models, parametric studies are conducted to broaden the understanding of the sensitivity of VIV induced fatigue damage to the seabed characteristic. The results indicate trench depth, vertical and lateral stiffness, and clay suction are significantly affect the VIV induced maximum fatigue damage at TDZ.
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Cross-flow VIV-induced fatigue damage of deepwater Steel Catenary Riser at touch-down point
China Ocean Engineering, 2014Co-Authors: Kunpeng Wang, Wenyong Tang, Hongxiang XueAbstract:A prediction model of the deepwater Steel Catenary Riser VIV is proposed based on the forced oscillation test data, taking into account the Riser-seafloor interaction for the cross-flow VIV-induced fatigue damage at touch-down point (TDP). The model will give more reasonable simulation of SCR response near TDP than the previous pinned truncation model. In the present model, the hysteretic Riser-soil interaction model is simplified as the linear spring and damper to simulate the seafloor, and the damping is obtained according to the dissipative power during one periodic Riser-soil interaction. In order to validate the model, the comparison with the field measurement and the results predicted by Shear 7 program of a full-scale Steel Catenary Riser is carried out. The main induced modes, mode frequencies and response amplitude are in a good agreement. Furthermore, the parametric studies are carried out to broaden the understanding of the fatigue damage sensitivity to the upper end in-plane offset and seabed characteristics. In addition, the fatigue stress comparison at TDP between the truncation Riser model and the present full Riser model shows that the existence of touch-down zones is very important for the fatigue damage assessment of Steel Catenary Riser at TDP.
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time domain prediction approach for cross flow viv induced fatigue damage of Steel Catenary Riser near touchdown point
Applied Ocean Research, 2013Co-Authors: Kunpeng Wang, Hongxiang Xue, Wenyong TangAbstract:Abstract Previous Steel Catenary Riser (SCR) models targeted for VIV prediction are truncated at touchdown point (TDP) where simple constrain and rotation stiffness are generally applied. In this study, a time domain approach accounting for the SCR–soil interaction is proposed to predict the cross-flow (CF) VIV induced fatigue damage of a SCR near TDP. The hydrodynamic force is simulated based on the forced vibration test data as a function of the non-dimensional amplitude and frequency, and an empirical damping model. When the non-dimensional frequency associated with the calculated frequency falls in the excitation region, the natural frequency closer to the frequency corresponding to the maximum excitation force is taken to be the dominant frequency, and applied to obtain the excitation force. The SCR–soil interaction model takes into account the trench shape, and the mobilization and release of the soil suction. Fatigue damage is linearly accumulated by using the rain-flow counting methodology. To validate the proposed models, simulation for a Riser model test is carried out, and the envelopes of RMS displacement, curvature, and fatigue damage are compared. Further works focus on the sensitivity of VIV induced fatigue damage near TDP to the seabed parameters, such as mudline shear strength, shear strength gradient and soil suction, and some conclusions are obtained.
Wenqing Zheng - One of the best experts on this subject based on the ideXlab platform.
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dynamic and fatigue analyses of stress joint for deepwater Steel Catenary Riser
ASME 2012 31st International Conference on Ocean Offshore and Arctic Engineering, 2012Co-Authors: Hezhen Yang, Wenqing ZhengAbstract:As the offshore industry continues to progress developments in deepwater, Steel Catenary Riser (SCR) offers great advantages over other Risers. In order to provide the hang-off with sufficient stiffness, stress joint is used to connect the Riser with platform. When stress joints are located at the top of a deep marine Riser, it is greatly affected by both axial and bending stress due to great cyclic loading. So it is necessary to do some research on dynamic and local fatigue analyses for stress joint.In this work, global dynamic analysis for a SCR is performed firstly, then local boundary condition obtained from the previous analysis are applied to the stress joint FE model for time domain dynamic and multiaxial fatigue analysis. Results indicate that the stress level is far lower than yield limit of material and damage induced by fatigue needs more attention. Besides, the damage character of the two types of stress joints differs: for TSJ, the place where stress joint connects with Riser is easy to occur fatigue damage; for SSJ, the most probable position is at the place where the end of inner sleeve pipe contacts with the Riser body. Compared with SSJ, TSJ shows a higher stress level but better fatigue performance, and it will have a higher material cost. Considering various factors, designers should choose the most suitable type and also geometric parameters.Copyright © 2012 by ASME
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metamodel approach for reliability based design optimization of a Steel Catenary Riser
Journal of Marine Science and Technology, 2011Co-Authors: Hezhen Yang, Wenqing ZhengAbstract:A reliability-based design optimization (RBDO) methodology is presented for the design of a Steel Catenary Riser (SCR) under dynamic environmental loads. The purpose of this work is to optimize the cost of products subjected to probabilistic constraints. Searching for the optimal design of the Riser in a wide range of design variables is computationally very expensive if time-consuming codes for dynamic analysis are necessary in the iteration process. In this study, the effectiveness of the proposed RBDO using a metamodel is firstly studied and validated through a beam test, then applied to the industrial dynamic optimization problem. The design variables of structures are assumed to be uncertain, and some other parameters such as loading and material properties are considered random. The performance function is approximated using metamodels to avoid time-consuming finite-element analysis during the optimization iteration. A single-loop method is used to decouple the double-loop RBDO problem. The reliability is finally confirmed through Monte Carlo simulations. According to the analysis, the presented methodology is more rational and realistic compared with deterministic optimization.
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Dynamic Optimization of Steel Catenary Risers Based on Reliability Using Metamodel
29th International Conference on Ocean Offshore and Arctic Engineering: Volume 5 Parts A and B, 2010Co-Authors: Wenqing Zheng, Hezhen YangAbstract:Reliability based design optimization (RBDO) of a Steel Catenary Riser (SCR) using metamodel is investigated. The purpose of the optimization is to find the minimum-cost design subjecting to probabilistic constraints. To reduce the computational cost of the traditional double-loop RBDO, a single-loop RBDO approach is employed. The performance function is approximated by using metamodel to avoid time consuming finite element analysis during the dynamic optimization. The metamodel is constructed though design of experiments (DOE) sampling. In addition, the reliability assessment is carried out by Monte Carlo simulations. The result shows that the RBDO of SCR is a more rational optimization approach compared with traditional deterministic optimization, and using metamodel technique during the dynamic optimization process can significantly decrease the computational expense without sacrificing accuracy.Copyright © 2010 by ASME
