Effects of Soil Non-Linearity on the Dynamic Behavior and Fatigue Life of Pipeline Spans Subjected to Slug Flow

2010 ◽  
Author(s):  
Euro Casanova ◽  
Armando Blanco
Keyword(s):  
Fatigue Life ◽  
Slug Flow ◽  
Element Model ◽  
Vibration Response ◽  
Perfectly Plastic ◽  
Equilibrium Configurations ◽  
Non Linear ◽  
Cyclic Damage ◽  
Pipeline Design ◽  
Soil Pipe

Offshore production fields require long submarine pipelines for transporting production fluids that are inherently multiphase. This condition and hydraulic sizing of pipelines lead often to the development of slug flow patterns in which condensate slugs traveling in the pipeline, act as moving gravity loads for the piping structure, therefore producing a dynamic response especially important for the free spans. Recently some authors have shown that this phenomenon may produce a cyclic damage that could reduce in a significant way the fatigue life of the pipelines, thus constituting a governing mechanism in their design. On the other hand, pipe-soil interaction has also been identified as an important factor in pipeline design and fatigue life; in particular it is important for determination of the static equilibrium configurations and the vibration response of free spanning pipelines. In this work a previously presented numerical model which combines fluid equations for predicting slug characteristics and a structural finite element model for the pipelines transporting slugs, is improved by introducing non linear characteristics of seabed supports. Different seabed supports (linear, perfectly plastic, and non linear with tension cut-off) and different properties of soil-pipe interaction (stiffness, damping and length of soil-pipe interaction) are considered, and their effects on vibration response and fatigue life are compared. Results show that soil pipe interaction is an important parameter in vibration response and fatigue life for pipeline spans subjected to slug flow.

Numerical Modeling of the Dynamical Interaction Between Slug Flow and Vortex Induced Vibration in Horizontal Submarine Pipelines

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Boris M. Bossio V. ◽  
Armando J. Blanco A. ◽  
Euro L. Casanova M.
Keyword(s):  
Fatigue Life ◽  
Flow Regime ◽  
Vortex Shedding ◽  
Slug Flow ◽  
Fluid Model ◽  
Reference Value ◽  
Dynamical Interaction ◽  
Vortex Induced Vibration ◽  
Resonance Effects ◽  
Cyclic Damage

Fatigue life of submarines pipelines is known to depend on many factors, e.g., materials, spanning length, vortex induced vibration (VIV), pipe soil-interaction, etc. In the case of VIV, the external flow due to marine currents can generate the well known alternate vortex shedding regime. In this regime, a time-varying pressure distribution over the surface of the pipeline imposes forces upon the pipeline itself, thus producing vibration with a defined frequency. On the other hand, in recent years some authors have shown that slug flow regime may produce a cyclic damage that could reduce in a significant way the fatigue life of submarine pipelines, thus constituting a governing mechanism in their design. In slug flow regime, slugs traveling in the pipe act as moving gravity loads for the pipeline structure, producing a dynamic response, especially important for the free spans. If both frequencies of the before mentioned effects are closer and, in addition, are in the same range of the natural frequency of the pipeline span, resonance effects can be expected to be reinforced and drastic changes in the dynamics of the pipeline could appear. In this work, a first study of the interaction between slug flow induced vibration in horizontal pipelines and cross-flow response due to vortex shedding is presented. The fluid model was based on the classical wake oscillator model. A numerical model based on the finite difference method was implemented for the structure. Two particular extreme cases were modeled to analyze the pipeline dynamics for “small-size” and “large-size” slugs, for a range of marine current velocities. For the case involving small-size slugs, it was observed a near 10% increment in the vibration amplitude (compared to a reference value), while in the case of “large-slugs” the VIV was overweighed by the slug induced vibration (SIV) phenomenon.

scholarly journals Evaluation of Moisture and Decay Models for a New Design Framework for Decay Prediction of Wood

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 721
Author(s):  
Jonas Niklewski ◽  
Philip Bester van Niekerk ◽  
Christian Brischke ◽  
Eva Frühwald Hansson
Keyword(s):  
Service Life ◽  
Wood Decay ◽  
Element Model ◽  
Digital Design ◽  
Design Guideline ◽  
Digital Performance ◽  
Detail Design ◽  
Non Linear ◽  
Service Life Design ◽  
Life Design

Performance-based, service-life design of wood has been the focus of much research in recent decades. Previous works have been synthesized in various factorized design frameworks presented in the form of technical reports. Factorization does not consider the non-linear dependency between decay-influencing effects, such as between detail design and climate variables. The CLICKdesign project is a joint European effort targeting digital, performance-based specification for service-life design (SLD) of wood. This study evaluates the feasibility of using a semi-empirical moisture model (SMM) as a basis for a digital SLD framework. The performance of the SMM is assessed by comparison against a finite element model (FEM). In addition, two different wood decay models (a logistic, LM, and simplified logistic model (SLM)) are compared. While discrepancies between the SMM and FEM were detected particularly at high wood moisture content, the overall performance of the SMM was deemed sufficient for the application. The main source of uncertainty instead stems from the choice of wood decay model. Based on the results, a new method based on pre-calculated time series, empirical equations, and interpolation is proposed for predicting the service life of wood. The method is fast and simple yet able to deal with non-linear effects between weather variables and the design of details. As such, it can easily be implemented as part of a digital design guideline to provide decision support for architects and engineers, with less uncertainty than existing factorized guidelines.

scholarly journals Fatigue Modeling and Numerical Analysis of Re-Filling Probe Hole of Friction Stir Spot Welded Joints in Aluminum Alloys

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2171
Author(s):  
Armin Yousefi ◽  
Ahmad Serjouei ◽  
Reza Hedayati ◽  
Mahdi Bodaghi
Keyword(s):  
Experimental Data ◽  
Tensile Strength ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Behavior ◽  
Element Model ◽  
Plastic Strain Amplitude ◽  
Friction Stir ◽  
Probe Hole ◽  
Good Agreement

In the present study, the fatigue behavior and tensile strength of A6061-T4 aluminum alloy, joined by friction stir spot welding (FSSW), are numerically investigated. The 3D finite element model (FEM) is used to analyze the FSSW joint by means of Abaqus software. The tensile strength is determined for FSSW joints with both a probe hole and a refilled probe hole. In order to calculate the fatigue life of FSSW joints, the hysteresis loop is first determined, and then the plastic strain amplitude is calculated. Finally, by using the Coffin-Manson equation, fatigue life is predicted. The results were verified against available experimental data from other literature, and a good agreement was observed between the FEM results and experimental data. The results showed that the joint’s tensile strength without a probe hole (refilled hole) is higher than the joint with a probe hole. Therefore, re-filling the probe hole is an effective method for structures jointed by FSSW subjected to a static load. The fatigue strength of the joint with a re-filled probe hole was nearly the same as the structure with a probe hole at low applied loads. Additionally, at a high applied load, the fatigue strength of joints with a refilled probe hole was slightly lower than the joint with a probe hole.

Durability Analysis of the Reduction Gear for High Speed Train Considering Driving Histories

2012 ◽  
Vol 586 ◽  
pp. 269-273
Author(s):  
Chul Su Kim ◽  
Gil Hyun Kang
Keyword(s):  
Fatigue Life ◽  
High Speed ◽  
Element Model ◽  
Rolling Stock ◽  
Reduction Gear ◽  
High Speed Train ◽  
Analysis Software ◽  
Tractive Effort ◽  
Durability Analysis ◽  
The Finite Element Model

To assure the safety of the power bogies for train, it is important to perform the durability analysis of reduction gear considering a variation of velocity and traction motor capability. In this study, two types of applied load histories were constructed from driving histories considering the tractive effort and the train running curves by using dynamic analysis software (MSC.ADAMS). Moreover, this study was performed by evaluating fatigue damage of the reduction gears for rolling stock using durability analysis software (MSC.FATIGUE). The finite element model for evaluating the carburizing effect on the gear surface was used for predicting the fatigue life of the gears. The results showed that the fatigue life of the reduction gear would decrease with an increasing numbers of stops at station.

Elasto-Plastic Coupled Temperature-Displacement Finite Element Analysis of Two-Dimensional Rolling-Sliding Contact With a Translating Heat Source

1991 ◽  
Vol 113 (1) ◽  
pp. 93-101 ◽  
Author(s):  
S. M. Kulkarni ◽  
C. A. Rubin ◽  
G. T. Hahn
Keyword(s):  
Finite Element ◽  
Half Space ◽  
Plastic Material ◽  
Element Model ◽  
Rolling Contact ◽  
Two Dimensional ◽  
Element Analysis ◽  
Element Mesh ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

The present paper, describes a transient translating elasto-plastic thermo-mechanical finite element model to study 2-D frictional rolling contact. Frictional two-dimensional contact is simulated by repeatedly translating a non-uniform thermo-mechanical distribution across the surface of an elasto-plastic half space. The half space is represented by a two dimensional finite element mesh with appropriate boundaries. Calculations are for an elastic-perfectly plastic material and the selected thermo-physical properties are assumed to be temperature independent. The paper presents temperature variations, stress and plastic strain distributions and deformations. Residual tensile stresses are observed. The magnitude and depth of these stresses depends on 1) the temperature gradients and 2) the magnitudes of the normal and tangential tractions.

The structural optimization of roadheader conical picks based on fatigue life

2018 ◽  
Vol 09 (02) ◽  
pp. 1850013 ◽  
Author(s):  
Zhenguo Lu ◽  
Lirong Wan ◽  
Qingliang Zeng ◽  
Xin Zhang ◽  
Kuidong Gao
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Static Analysis ◽  
Element Model ◽  
Cutting Resistance ◽  
Strength Failure ◽  
New Type ◽  
Conical Picks ◽  
Fatigue Life Analysis ◽  
The Finite Element Model

Conical picks are the key cutting components used on roadheaders, and they are replaced frequently because of the bad working conditions. Picks did not meet the fatigue life when they were damaged by abrasion, so the pick fatigue life and strength are excessive. In the paper, in order to reduce the abrasion and save the materials, structure optimization was carried out. For static analysis and fatigue life prediction, the simulation program was proposed based on mathematical models to obtain the cutting resistance. Furthermore, the finite element models for static analysis and fatigue life analysis were proposed. The results indicated that fatigue life damage and strength failure of the cutting pick would never happen. Subsequently, the initial optimization model and the finite element model of picks were developed. According to the optimized results, a new type of pick was developed based on the working and installing conditions of the traditional pick. Finally, the previous analysis methods used for traditional methods were carried out again for the new type picks. The results show that new type of pick can satisfy the strength and fatigue life requirements.

Stress and Fatigue Life Modeling of Cannon Breech Closures Including Effects of Material Strength and Residual Stress

2000 ◽  
Vol 123 (1) ◽  
pp. 150-154
Author(s):  
John H. Underwood ◽  
Michael J. Glennon
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Fatigue Life ◽  
Yield Strength ◽  
Residual Stresses ◽  
Solid Mechanics ◽  
Element Model ◽  
Pressure Vessels ◽  
Material Strength ◽  
Element Analysis

Laboratory fatigue life results are summarized from several test series of high-strength steel cannon breech closure assemblies pressurized by rapid application of hydraulic oil. The tests were performed to determine safe fatigue lives of high-pressure components at the breech end of the cannon and breech assembly. Careful reanalysis of the fatigue life tests provides data for stress and fatigue life models for breech components, over the following ranges of key parameters: 380–745 MPa cyclic internal pressure; 100–160 mm bore diameter cannon pressure vessels; 1040–1170 MPa yield strength A723 steel; no residual stress, shot peen residual stress, overload residual stress. Modeling of applied and residual stresses at the location of the fatigue failure site is performed by elastic-plastic finite element analysis using ABAQUS and by solid mechanics analysis. Shot peen and overload residual stresses are modeled by superposing typical or calculated residual stress distributions on the applied stresses. Overload residual stresses are obtained directly from the finite element model of the breech, with the breech overload applied to the model in the same way as with actual components. Modeling of the fatigue life of the components is based on the fatigue intensity factor concept of Underwood and Parker, a fracture mechanics description of life that accounts for residual stresses, material yield strength and initial defect size. The fatigue life model describes six test conditions in a stress versus life plot with an R2 correlation of 0.94, and shows significantly lower correlation when known variations in yield strength, stress concentration factor, or residual stress are not included in the model input, thus demonstrating the model sensitivity to these variables.

Soil-Pipe Interaction Models for the Simulation of Buried Steel Pipeline Behaviour Against Geohazards

2017 ◽  
Author(s):  
Gregory C. Sarvanis ◽  
Spyros A. Karamanos ◽  
Polynikis Vazouras ◽  
Panos Dakoulas ◽  
Elisabetta Mecozzi ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Experimental Testing ◽  
Complex Loading ◽  
Full Scale ◽  
Design Calculation ◽  
Analytical Methodology ◽  
Interaction Models ◽  
Rigorous Model ◽  
Pipeline Design ◽  
Soil Pipe

Hydrocarbon pipelines constructed in geohazards areas, are subjected to ground-induced actions, associated with the development of severe strains in the pipeline and constitute major threats for their structural integrity. In the course of pipeline design, calculation of those strains is necessary for safeguarding pipeline integrity, and the development of reliable analytical/numerical design tools that account for soil-pipe interaction is required. In the present paper, soil-pipe interaction models for buried steel pipelines subjected to severe ground-induced actions are presented. First, two numerical methodologies, (simplified and rigorous) and one analytical are presented and compared, followed by an experimental verification; transversal soil-pipe interaction is examined through full-scale experimental testing, and comparisons of numerical simulations with rigorous finite element models are reported. Furthermore, the rigorous model is compared with the results from a special-purpose full-scale “landslide/fault” experimental test in order to examine the soil-pipe interaction in a complex loading conditions. Finally, the verified rigorous model is compared with both the simplified models and the analytical methodology.

The Dynamic Behavior of a Rolling Element Auxiliary Bearing Following Rotor Impact

2001 ◽  
Vol 124 (2) ◽  
pp. 406-413 ◽  
Author(s):  
M. O. T. Cole ◽  
P. S. Keogh ◽  
C. R. Burrows
Keyword(s):  
Dynamic Behavior ◽  
Angular Acceleration ◽  
Element Model ◽  
Magnetic Bearing ◽  
Rolling Element Bearing ◽  
Linear Matrix ◽  
Rolling Element ◽  
Non Linear ◽  
In Series ◽  
Inner Race

The dynamic behavior of a rolling element bearing under auxiliary operation in rotor/magnetic bearing systems is analyzed. When contact with the rotor occurs, the inner race experiences high impact forces and rapid angular acceleration. A finite element model is used to account for flexibility of the inner race in series with non-linear ball stiffnesses arising from the ball-race contact zones. The dynamic conditions during rotor/inner race contact, including ball/race creep, are deduced from a non-linear matrix equation. The influences of bearing parameters are considered together with implications for energy dissipation in the bearing.

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