Fatigue Testing and Analysis of a Deep Water Steel Tube Umbilical

2008 ◽  
Author(s):  
Alan Dobson ◽  
Dave Fogg
Keyword(s):  
Mathematical Model ◽  
Fatigue Testing ◽  
Steel Tube ◽  
Steel Tubes ◽  
Stick Slip ◽  
Stress Variation ◽  
Slip Mechanism ◽  
Deep Waters ◽  
Bending Loads ◽  
The Mathematical Model

Rapid analysis of dynamic umbilical structures during the design phase requires a robust mathematical model of the component stresses due to static and alternating loads. The following discusses the validation of a model, through full scale testing, used to assess the stresses and strains present within steel tubes, in umbilical structures typically used in dynamic service in deep waters, such as found in the Gulf of Mexico and offshore West Coast of Africa. The validation focuses upon the complexity of the mathematical model and the influence of tension magnitude the stick-slip mechanism and the stress variation around the circumference of the tubes when under the influence of bending loads.

Dynamic Analysis for the Design of CALM System in Shallow and Deep Waters

1997 ◽  
Vol 119 (3) ◽  
pp. 151-157 ◽  
Author(s):  
Y.-L. Hwang
Keyword(s):  
Mathematical Model ◽  
Dynamic Analysis ◽  
Model Test ◽  
Time Domain ◽  
Time Domain Analysis ◽  
Mooring Lines ◽  
Deep Waters ◽  
Wave Drift ◽  
The Mathematical Model ◽  
Survival Condition

This paper presents a time domain analysis approach to evaluate the dynamic behavior of the catenary anchor leg mooring (CALM) system under the maximum operational condition when a tanker is moored to the terminal, and in the survival condition when the terminal is not occupied by a tanker. An analytical model, integrating tanker, hawser, buoy, and mooring lines, is developed to dynamically predict the extreme mooring loads and buoy orbital motions, when responding to the effect of wind, current, wave frequency, and wave drift response. Numerical results describing the dynamic behaviors of the CALM system in both shallow and deepwater situations are presented and discussed. The importance of the line dynamics and hawser coupled buoy-tanker dynamics is demonstrated by comparing the present dynamic analysis with catenary calculation approach. Results of the analysis are compared with model test data to validate the mathematical model presented.

Influencing Factors on Stick-Slip Behavior of a Ball Screw Driven Elevation Mechanism for MLRS

2012 ◽  
Vol 271-272 ◽  
pp. 958-968
Author(s):  
Young Hyu Choi ◽  
Sung Hyun Jang ◽  
Ji Han Oh
Keyword(s):  
Mathematical Model ◽  
Ball Screw ◽  
Force Model ◽  
Stick Slip ◽  
Single Degree Of Freedom ◽  
Stribeck Effect ◽  
The Stability ◽  
Friction Parameters ◽  
The Mathematical Model ◽  
Rocket System

As an MLRS (Multiple Launch Rocket System) cage is moved with a uniform speed through an elevation mechanism for MRLS operated using ball screws, its stick-slip behavior can be observed by the friction in a ball screw actuator. In this study, a single-degree of freedom mathematical model of an MLRS elevation system is designed and its stick-slip behavior is analyzed using a friction force model considering the Stribeck effect. The stability of a vibration system is analyzed through deriving an equation of normalized motion for the mathematical model and the influences of mechanical parameters and friction parameters on the vibration response and stability are theoretically analyzed.

Modeling and Simulation of Stick-Slip Motion for Pneumatic Cylinder Based on Meter-In Circuit

2011 ◽  
Vol 130-134 ◽  
pp. 775-780 ◽  
Author(s):  
Peng Fei Qian ◽  
Guo Liang Tao ◽  
Jian Feng Chen ◽  
Bo Lu
Keyword(s):  
Mathematical Model ◽  
Pneumatic Cylinder ◽  
Practical Application ◽  
Stick Slip ◽  
Slip Mechanism ◽  
Runge Kutta Method ◽  
Variable Step ◽  
Order Variable ◽  
Stick Slip Motion ◽  
Slip Motion

For the stick-slip phenomenon encountered in the pneumatic cylinder motion in practical application, the stick-slip mechanism was analyzed and an nonlinear mathematical model based on the improved LuGre model of pneumatic cylinder movement was established. The movement of the piston and the pressure of the rodless chamber in the pneumatic cylinder based on meter-in circuit were obtained through solving the differential equations by four-order variable-step Runge-Kutta method. The comparison between simulation and experimental results shows that the established mathematical model can describe the stick-slip motion of pneumatic cylinder with a relatively good accuracy.

scholarly journals Phenomenological model of the generation of the seismic mode «drumbeats» earthquakes accompanying the eruption of Kizimen volcano in 2011-2012

2020 ◽  
pp. 86-101
Author(s):  
А.А. Шакирова ◽  
П.П. Фирстов ◽  
Р.И. Паровик
Keyword(s):  
Lava Flow ◽  
Phenomenological Model ◽  
Nonlinear Oscillator ◽  
Time Intervals ◽  
Stick Slip ◽  
Slip Mechanism ◽  
Long Time ◽  
The Mathematical Model ◽  
First Time ◽  
Mode Generation

Извержение вулкана Кизимен в 2011-2012 гг. характеризовалось устойчивым, почти равномерным выжиманием вязкого лавового потока объемом 0.3 км³. Формирование лавового потока сопровождалось возникновением квазипериодических землетрясений режима «drumbeats» с энергетическими классами Ks<7, регистрируемых на длительных временных участках. Показано, что землетрясения генерировались движением фронта вязкого лавового потока, что в практике вулканологических исследований наблюдалось впервые. Предложена феноменологическая модель генерации сейсмического режима «drumbeats». Движение фронта лавового потока по склону вулкана происходило в результате прерывистого скольжения с включением механизма «stick-slip» и возбуждением автоколебательного процесса с генерацией сейсмического режима «drumbeats». Правдоподобность феноменологической модели режима ««drumbeats» на качественном уровне подтверждена математической моделью дробного нелинейного осциллятора. The eruption of the Kizimen volcano in 2011-2012 characterized by stable, almost uniform squeezing of a viscous lava flow with a volume of 0.3 km³. The formation of the lava flow was accompanied by the occurrence of quasiperiodic earthquakes of the “drumbeats” mode with energy classes Ks < 7, recorded at long time intervals. Shown that earthquakes were generated by the movement of the front of a viscous lava flow, which was observed for the first time in the practice of volcanological research. A phenomenological model of “drumbeats” seismic mode generation is proposed. The movement of the front of the lava flow along the slope of the volcano occurred because of intermittent sliding with the inclusion of the «stick-slip» mechanism and the initiation of a self-oscillating process with the generation of a seismic mode «drumbeats». The mathematical model of a fractional nonlinear oscillator qualitatively confirms the plausibility of the phenomenological model of the “drumbeats” mode.

scholarly journals Scientific Rationale for the Movable Pipeline Technology for Transporting CNG by Sea

2020 ◽  
Vol 28 (3) ◽  
pp. 168-177
Author(s):  
Oleh Mandryk ◽  
Volodymyr Artym ◽  
Mariana Shtohry ◽  
Valerii Zaytsev
Keyword(s):  
Mathematical Model ◽  
Natural Gas ◽  
Frame Structure ◽  
Steel Tubes ◽  
Module Design ◽  
Layer Composite ◽  
Economic Parameters ◽  
The Mathematical Model ◽  
Standard Steel ◽  
Made In

AbstractA new efficient CNG module design for the transportation of natural gas by sea is proposed and substantiated. A mathematical model for determining the technical and economic parameters of a movable pipeline module, which is designed for transporting natural gas in a compressed state and consists of a frame structure, the dimensions of which correspond to the 40-foot marine container size and a pipe coil is described. To facilitate construction, it is proposed that a large portion of the coil be made in the form of a two-layer composite construction. The inner layer consists of standard steel tubes or adapters, and the outer layer is fiberglass wound on them. On the basis of the mathematical model an algorithm and a program were compiled, which allowed to determine the technical and economic parameters of the movable pipeline module. The results obtained for the Caspian region are analyzed.

Validated Methodology for Calculating Fatigue Capacity of Deepwater Umbilicals

2018 ◽  
Author(s):  
Adrian Connaire ◽  
Krassimir Doynov ◽  
Ruairi Nestor ◽  
Venkat Krishnan
Keyword(s):  
Dynamic Test ◽  
Cyclic Stress ◽  
Steel Tube ◽  
Full Scale ◽  
Contact Forces ◽  
Hysteretic Behavior ◽  
Steel Tubes ◽  
Large Power ◽  
Industry Standard ◽  
Bending Loads

Steel tube umbilical designs are becoming more complex and are being deployed in increasingly severe environments. Umbilical designs can now accommodate up to 3-inch diameter steel tubes for chemical and hydraulic injection, up to four layers of armoring, multiple electrical cables and fiber optic lines. Large power transmission cables are also being incorporated in umbilical constructions. This is leading to ever increasing umbilical mass, radial loads, pressure loads and increased demands on the designer to demonstrate adequate fatigue capacity. A method has been developed for predicting the fatigue response of deepwater umbilicals, particularly for umbilicals subject to high tension and bending loads. The method involves predicting cyclic stress in the umbilical components (steel tubes or power cables) using an industry standard, general purpose numerical tool. It comprehensively accounts for the complex relationships between umbilical curvature, tension, inter-layer contact forces and tube stress variation. This paper describes the validation of the method against measured data obtained from full scale fatigue tests performed on two deepwater umbilicals. A key feature of the method relates to the construction and verification of suitable finite element (FE) models and the simulation of fatigue conditions. For the validation of the models, results from the full scale dynamic umbilical test cases incorporating bend stiffeners and loading arms are used, which demonstrate umbilical hysteretic behavior under cyclic bending loads. Hysteretic stress-curvature loops obtained from strain gauge readings for various tube locations within the bend stiffener regions for two umbilical constructions with significantly different lay-up configurations and fatigue stress regimes are used for comparison to strain predictions from the FE models. A significant advantage of the modelling and analysis methods described in this paper is that it employs the widely-used industry standard numerical FE tool, Abaqus, for the modelling and analysis of the umbilical. Key features and insights from the modelling, analysis approach and validation against the results of a deepwater umbilical dynamic test program are described. A robust and efficient method for the independent assessment of the fatigue capacity of deepwater umbilicals is demonstrated.

Modeling and Simulation of the Ultrasonic Motor which Using Bending Vibration Transducer

2014 ◽  
Vol 628 ◽  
pp. 240-248
Author(s):  
Zi Li Huang ◽  
Wei Shan Chen
Keyword(s):  
Mathematical Model ◽  
Computer Simulations ◽  
Mechanical Model ◽  
Ultrasonic Motor ◽  
Guide Rail ◽  
Bending Vibration ◽  
Stick Slip ◽  
Vibration Transducer ◽  
Starting Process ◽  
The Mathematical Model

Build the mathematical model and mechanical model of ultrasonic motor which using bending vibration transducer. Based on this model, analyze the contact and friction processes between driven-foot which belonging to ultrasonic motor which using bending vibration transducer and guide rail. Analyze the influence preload force make to the process of motor’s running. Take the cases of stick, slip, flight into consideration, and explain nonlinearity of the Dynamics. Do computer simulations of starting process though this model, and summarize the motor’s working results when it works under different conditions.

Dynamic Response of Two-Disk Systems With Friction and Misalignment

1998 ◽  
Author(s):  
Ahmed Anabtawi ◽  
Kambiz Farhang
Keyword(s):  
Mathematical Model ◽  
Dynamic Response ◽  
Contact Stiffness ◽  
Stick Slip ◽  
Torsional Response ◽  
Damping Characteristics ◽  
Disk Friction ◽  
Stiffness And Damping ◽  
The Mathematical Model ◽  
Friction Induced Vibration

Abstract Friction induced vibration and noise pose one of the most challenging problems. The complexity of the friction system arises due to the nonlinear nature of friction phenomena and that of contact stiffness and damping. This paper presents a mathematical model for studying the dynamic response of two-disk friction system in the presence of misalignment. The contact stiffness and damping characteristics of the system are represented in the axial as well as the torsional directions. In addition, the axial and torsional responses of the system are coupled by assuming dependency between the torsional response and the normal force between the two disks. Using the mathematical model, various scenarios are examined to study the effect of misalignment. These include cases of symmetric and asymmetric actuation forces as well as forces applied at unequal actuation times. The results suggest that asymmetry in actuation forces has negligible effect on stick-slip behavior of the system.

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