Effect of Anti-Wear Tape on Behavior of Flexible Risers

2014 ◽  
Author(s):  
Chongyao Zhou ◽  
Naiquan Ye ◽  
Svein Sævik
Keyword(s):  
Numerical Analysis ◽  
Numerical Model ◽  
Cross Section ◽  
Bending Moment ◽  
Laboratory Measurements ◽  
Flexible Riser ◽  
Bending Loads ◽  
Flexible Risers ◽  
Bending Behavior ◽  
The Impact

The service life of a flexible riser is often dominated by the metallic layers under cyclic bending loads, particularly the tensile armor layers. The effect of the anti-wear tapes is normally omitted during cross section modelling, where a plane-remain-plane assumption is usually used for stick condition. Significant differences have been observed between numerical analysis assuming plane surfaces remain plane and laboratory measurements studying the bending moment versus curvature for a flexible riser which has anti-wear tapes between the two tensile armor layers. A new shear interaction algorithm has been developed in the numerical model to improve the modeling of the anti-wear tapes by taking the thickness and shear modulus of the anti-wear material into account. The impact of these parameters on the bending behavior of the flexible riser is demonstrated by comparing the numerical analysis results with the laboratory measurements.

scholarly journals The Effect of Stick Stiffness of Friction Models on the Bending Behavior in Non-Bonded Flexible Risers

2017 ◽  
Author(s):  
Tianjiao Dai ◽  
Naiquan Ye ◽  
Svein Sævik
Keyword(s):  
Shear Deformation ◽  
Numerical Study ◽  
Bending Moment ◽  
Friction Stress ◽  
Friction Model ◽  
Stiffness Reduction ◽  
Friction Models ◽  
Flexible Risers ◽  
Bending Behavior ◽  
Full Scale Tests

This paper investigates the effect of stick stiffness on the bending behavior in non-bonded flexible risers. The stick stiffness was normally implemented in the friction model for calculating the friction stress between layers in such structures. As the stick stiffness may be too small to achieve the plane-surfaces-remain-plane assumption under low contact pressure in some friction models [1], a new friction model was proposed for maintaining the constant stick stiffness in the present work. Less stick stiffness than that obtained by the plane-surfaces-remain-plane assumption was observed in test data. It was assumed that the stick stiffness reduction is caused by shear deformation of plastic layers. A numerical study on stick stiffness by including the shear deformation effect was carried out and verified against full scale tests with respect to the bending moment-curvature relationship.

Theoretical and numerical analysis of bending behavior of unbonded flexible risers

2015 ◽  
Vol 44 ◽  
pp. 311-325 ◽  
Author(s):  
Mengmeng Zhang ◽  
Xiqia Chen ◽  
Shixiao Fu ◽  
Yousong Guo ◽  
Leixin Ma
Keyword(s):  
Numerical Analysis ◽  
Flexible Risers ◽  
Bending Behavior ◽  
Theoretical And Numerical Analysis

Effect of Blade Geometry and Foreign Object Kinetic Energy on Blades Damage

2010 ◽  
Author(s):  
Mickhail S. Nikhamkin ◽  
Leonid V. Voronov ◽  
Irina V. Semenova
Keyword(s):  
Numerical Analysis ◽  
Numerical Model ◽  
Kinetic Energy ◽  
Leading Edge ◽  
Material Behavior ◽  
Plastic Strain Rate ◽  
Problem Solution ◽  
Foreign Object ◽  
The Impact ◽  
Blade Leading Edge

One of the main reasons of engine failure is foreign object damage (FOD) of compressor blades. Engine manufactures are constantly searching for blade endurance increasing methods. The problem solution requires investigation in the field of the structural factor effects on the blade damageability. The paper describes numerical analysis method of the damage process. Based on “the typical damage case” concept, this method can simulate typical blade damages: dents, tears, notches. The numerical analysis is performed by the finite element method (FEM). Material behavior is described with an elastic-plastic strain rate dependent model. Blade damage numerical model is thoroughly verified by the results of special experiments. To implement the experimental modeling, actual blades were damaged, a special experimental setup based on a pneumatic gun being used. The foreign object kinematic parameters before and after the impact, a blade leading edge displacements and residual deformation fields registered in the experiment are used as verification criteria for the numerical model. The blade leading edge thickness and a foreign object energy effect on the blade damageability is investigated. The research showed there are some foreign object kinetic energy critical values at which the damage mechanism and type are changed.

scholarly journals Acoustic wood tomography on trees and the challenge of wood heterogeneity

Holzforschung ◽  
2009 ◽  
Vol 63 (1) ◽  
Author(s):  
Sandy Schubert ◽  
Daniel Gsell ◽  
Jurg Dual ◽  
Masoud Motavalli ◽  
Peter Niemz
Keyword(s):  
Numerical Analysis ◽  
Numerical Model ◽  
Cross Section ◽  
Elastic Waves ◽  
Laboratory Experiments ◽  
Time Inversion ◽  
Fungal Decay ◽  
Tree Stability ◽  
Travel Time Inversion ◽  
Tomographic Measurement

Abstract The assessment of tree stability requires information about the location and the geometry of fungal decay or of a cavity in the interior of the trunk. This work aims at specifying which size of decay or cavity can be detected non-destructively by acoustic wood tomography. In the present work, the elastic waves that propagate in a trunk during a tomographic measurement were visualized by numerical simulations. The numerical model enabled to systematically investigate the influence of fungal decay on tomographic measurements neglecting the heterogeneity of wood. The influence of wood heterogeneity was studied in laboratory experiments on trunks. The experiments indicated that the waveforms of the measured signals are by far more sensitive to the natural heterogeneity of trunk wood than the travel times, thereby making waveforms unsuitable for decay detection. Thus, it is recommended to further develop the travel time inversion algorithms for trunks and to neglect the information in waveforms or amplitudes. Fungal decay is detectable if the influence of the decay is distinguishable from the influence of the heterogeneity. It was found from the numerical analysis that the cross-section of a cavity, which is larger than 5% of the total cross-section of the trunk, can be detected by acoustic wood tomography.

A Study on the Extensional-Torsional Response of a Damaged Flexible Pipe

2012 ◽  
Author(s):  
Héctor E. M. Merino ◽  
José Renato M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Numerical Model ◽  
Load Capacity ◽  
Torsional Stiffness ◽  
Flexible Riser ◽  
Flexible Pipe ◽  
Full Data ◽  
Torsional Response ◽  
Tension Tests ◽  
Flexible Risers ◽  
Unbonded Flexible Riser

Inspections in flexible risers have detected a considerable number of damages in their top section caused by the installation process or generated during their operation, due to the contact with another riser or components of the floating facility. Among the most common damages detected, the rupture of the tensile armor wires is critical to the structure integrity as its load capacity may be significantly reduced. The objective of this work is to present the main results involving pure tension and torsion with tension tests in a 4” unbonded flexible riser with five damaged wires in its outer tensile armor. These tests were carried out at the Structures Laboratory of Federal University of Rio de Janeiro (LabEst). Besides presenting full data concerning the internal structure of the riser, this paper describes the experimental procedures used to perform the tests and the main results obtained such as axial and torsional stiffness and the redistribution of forces in the wires. Comparisons between numerical simulations with those obtained experimentally are presented. A brief discussion about results and some simplifications assumed on the numerical model are presented at the end of the work.

scholarly journals Numerical modelling of the rigid polyurethane foam microstructure

2018 ◽  
Vol 157 ◽  
pp. 06008
Author(s):  
Zbigniew Pozorski
Keyword(s):  
Numerical Model ◽  
Polyurethane Foam ◽  
Cross Section ◽  
Parametric Analysis ◽  
Cell Structure ◽  
Rigid Polyurethane Foam ◽  
Material Parameters ◽  
The Impact ◽  
External Loads ◽  
Selection Of

The paper presents a numerical model of 2-D microstructure of rigid polyurethane foam. The selection of geometric and material parameters is presented. For a particular structure, its behavior has been studied for typical cases of external loads (or forced displacements). The characteristic phenomena have been identified and described. A parametric analysis was performed due to the dimension of the cross-section of the struts which form the cell edges. An analysis of the impact of support and loading conditions on the behavior of the cell structure was performed.

scholarly journals Effects of the Mortar Matrix on the Flexural Capacity of Masonry Cross Sections Strengthened with FRCM Materials

2020 ◽  
Vol 10 (21) ◽  
pp. 7908
Author(s):  
Giovanni Crisci ◽  
Giancarlo Ramaglia ◽  
Gian Piero Lignola ◽  
Francesco Fabbrocino ◽  
Andrea Prota
Keyword(s):  
Epoxy Resin ◽  
Cross Section ◽  
Cross Sections ◽  
Structural Engineering ◽  
Bending Moment ◽  
Fiber Reinforced ◽  
Flexural Capacity ◽  
Flexural Response ◽  
The Impact ◽  
Mortar Matrix

The strengthening intervention strategies that exist for masonry buildings are based on the use of thin composites and are a recent activity used in structural engineering. Nowadays, mortar matrices are frequently found instead of epoxy resins, since the fiber reinforced cementitious matrix (FRCM) composites are more compatible with masonry than fiber reinforced plastic (FRP) ones. The mortar matrix in FRCM composites is not comparable to the epoxy resin, and therefore its contribution is different not only in traction but above all on the compression side. Due to its larger thickness, if compared to the epoxy resin, the impact of the mortar matrix on the flexural response of strengthened cross sections is not negligible. This paper aimed to investigate the influence of the contribution of the mortar matrix on the compression side on the flexural capacity of strengthened cross section. As such, p–m interaction domains and bending moment–curvature diagrams were evaluated to understand the influence of several mechanical properties of fiber and mortar matrices on FRCM efficiency, typical of real applications. Hence, the impact of several constitutive relationships of composites (linear and bilinear behavior) was considered for the structural analysis of the strengthened cross section. The presented results are all completely in a dimensionless form; therefore, independent of geometry and mechanical parameters can be the basis for developing standardized design and/or verification methodologies useful for the strengthening systems for masonry elements.

Flexible Riser Fatigue Evaluation for FPSO’s in Bi-Directional Sea Spectra

2003 ◽  
Author(s):  
Carlos Alberto Duarte de Lemos ◽  
Murilo Augusto Vaz ◽  
Marcos Queija de Siqueira
Keyword(s):  
Operational Experience ◽  
Flexible Riser ◽  
Mooring Lines ◽  
Directional Spectrum ◽  
Campos Basin ◽  
Calculation Methodology ◽  
Flexible Risers ◽  
Fatigue Evaluation ◽  
Simplified Procedure ◽  
The Impact

The fatigue calculation methodology applied to flexible risers connected to FPSOs, offshore Brazil, is based on a simplified procedure considering a deterministic regular wave approach and a wave heading distribution supported by past operational experience with semi-submersible platforms. However the utilization of deterministic waves approach does not necessarites guarantee the consideration of the worst sea conditions, and the weathervaning capability of those systems are usually not accounted for when non-collinear wave, wind and current are present. A new procedure is being evaluated considering an integrated model for ship, mooring lines and risers to define the distribution of ship headings for fatigue analysis using an irregular bi-directional sea approach. The impact on a flexible riser’s fatigue life will be evaluated when a new ship heading distribution with irregular bi-directional spectrum is presented for the case of a FPSO with bow turret in operation at the Marlin Field offshore Campos Basin.

Evaluation of Contact Forces in the Vertical Connection of a Flexible Riser in the Subsea Equipment

2019 ◽  
Author(s):  
Yuri Coelho Del’ Sarto ◽  
Ricardo Franciss ◽  
Celso Kazuyuki Morooka
Keyword(s):  
Production Systems ◽  
Bending Moment ◽  
Contact Forces ◽  
Flexible Riser ◽  
Shear Forces ◽  
Flexible Pipe ◽  
Operational Procedure ◽  
Numerical Simulation Result ◽  
Operational Design ◽  
Flexible Risers

Abstract Flexible risers are commonly used in ultra deepwater offshore fields to convey fluids from the subsea equipment to the floating production unit. During the development of the production systems, the flexible pipe installation is a critical operation. In this scenario, an operational procedure for the installation frequently used in offshore Brazil is known as Direct Vertical Connection. In this concept, the Vertical Connection Module (VCM) is connected to the flexible pipe through a flanged joint, and lowered in to the subsea equipment with assistance of an installing cable. During the installation procedure, excessive loads may occur in the VCM due to reaction loads induced by the flexible pipe. The present paper aims to describe the Direct Vertical Connection installation and to propose a methodology to study the forces induced by the flexible pipe into the VCM during such operation. For this purpose, a numerical model is developed for the Direct Vertical Connection and it is represented to simulate the installation procedure through a commercial software OrcaFlex. The dynamic behavior of the system is investigated by varying the payout velocity of the installing cable, and the results are shown in terms of bending moment, wall tension and shear forces acting in the flange of the VCM. Numerical simulation result in the present work allows to evaluate the range of loading which acts during the Direct Vertical Connection to help operational design of the installation process, and avoid failure of components during the procedure.

Examination of Various Bending Moments on the Run Side and on the Branch Side for the Stress Index C2 of ASME NB-3600 Class 1 Branch Connections

2016 ◽  
Author(s):  
Umar Faraz ◽  
Robert Gurdal
Keyword(s):  
Cross Section ◽  
Branch Pipe ◽  
Bending Moment ◽  
Additional Stress ◽  
Main Question ◽  
Bending Moments ◽  
Technical Paper ◽  
Class 1 ◽  
The Impact ◽  
Stress Analyses

Previous stress analyses have shown that the requirement of exclusively using the branch pipe cross-section properties for the NB-3600 Class 1 branch connection stress analyses can be very severe (conservative), when compared with using the branch nozzle cross-section properties. In the analyses performed for a 2015 PVP technical paper (Ref. 2), one of the questions raised was the fact that only two specified bending moments were used in those previous stress analyses: 1,000,000 in-lbf as the run bending moment and 20,000 in-lbf as the branch bending moment. In fact, that was the main question that was raised. Therefore, the purpose of this technical paper is to perform additional stress analyses, based on various bending moments on the run side and on the branch side. The impact of using these various bending moments will be evaluated. The 2001 Edition of the ASME-Code removed a note at the bottom of the branch connection NB-3600 Figure. This note is required to be able to perform more accurate NB-3600 piping stress analyses of the branch connection. There is at this time a suggestion to restore that note.

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