A Methodology for Assessment of Internal Flow-Induced Vibration (FIV) in Subsea Piping Systems

2011 ◽  
Author(s):  
Yetzirah Urthaler ◽  
Lyle E. Breaux ◽  
Scot I. McNeill ◽  
Eric M. Luther ◽  
Julian Austin ◽  
...  
Keyword(s):  
Vibration Spectrum ◽  
Internal Flow ◽  
Measured Data ◽  
Model Verification ◽  
Modal Parameters ◽  
Response Analysis ◽  
Fe Model ◽  
Vibration Data ◽  
Forcing Function ◽  
Piping Systems

A methodology is presented for assessing internal flow-induced vibrations (FIV) in subsea piping systems. Finite Element (FE) models are constructed for the subject piping systems, including insulation, internal hydrocarbon weight and added mass of the surrounding sea water. Operating vibration data are measured using ROV-deployable accelerometer loggers clamped directly to the piping systems. The measured data are processed, analyzed and used for two purposes: model verification and dynamic response correlation. Modal parameters are extracted from the measured data and compared to the modal parameters computed from the structural FE model. The model is refined until the frequencies and mode shape errors are within the desired tolerance. The measured data are then used to derive a representative forcing function for use with frequency-domain random response analysis. The forcing function is derived such that the properties of the predicted vibration spectrum match those of the measured vibration spectrum for all measurement locations. The method presented herein provides a novel semi-empirical technique for calibrating FE models to make fatigue life predictions for subsea piping systems using measured vibration data.

Bending Flexibility of Bolted Flanges and Its Effect on Dynamical Behavior of Structures

1989 ◽  
Vol 111 (4) ◽  
pp. 392-398 ◽  
Author(s):  
A. Lifson ◽  
A. J. Smalley
Keyword(s):  
Natural Frequencies ◽  
Dynamical Behavior ◽  
Measured Data ◽  
Model Verification ◽  
Mode Shapes ◽  
Vibration Modes ◽  
Reciprocating Compressor ◽  
Southwest Research Institute ◽  
Piping Systems ◽  
Good Agreement

This paper presents a basis for determining the bending flexibility of flanged joints in complex piping systems for use in predicting natural frequencies, mode shapes, and response to excitation forces. Data was developed by a combination of laboratory testing and analysis. Highly instrumented testing initially identified and isolated the contributing deformations in a flanged joint and later provided overall flexibilities of flanged assemblies for verification of the analytical model. The analysis, its results, and model verification are presented in the paper. Further results are provided which compare predicted dynamic characteristics of reciprocating compressor manifold piping systems with measured data obtained in the field for vibration modes which are sensitive to flange flexibility. Consistent good agreement has been achieved of the techniques utilized in some 50 design and field analyses conducted at the Center for Applied Machinery and Piping Technology (CAMPT) at Southwest Research Institute.

Vibration Analysis of a Screw Pump Unit

2013 ◽  
Vol 753-755 ◽  
pp. 1727-1730
Author(s):  
Yue Zhang ◽  
You Hong Xiao ◽  
Jun Weng ◽  
Wan You Li
Keyword(s):  
Mathematical Method ◽  
Vibration Analysis ◽  
Vibration Spectrum ◽  
Vibration Response ◽  
Fe Model ◽  
Force Response ◽  
Pump Unit ◽  
Surface Integral ◽  
Screw Pump

In this paper, the vibration of a three screw pump was studied. Firstly the vibration response of the pump was tested. Then the FE model of the pump was constructed and the modals of it were calculated. The exactness of the result was confirmed by the testing modals and the reasonable of the FE model was verified at the same time. Finally, the force acted on rotors due to pressure was calculated by the mathematical method of surface integral. The force was loaded on the FE model and the force response was predicted, which represented the basic vibration of the screw pump. Based on the work above, the vibration spectrum of the screw pump was analyzed.

Managing Flow Induced Vibration in Subsea Jumpers

2021 ◽  
Author(s):  
Rakshith Naik ◽  
Yetzirah Urthaler ◽  
Scot McNeill ◽  
Rafik Boubenider
Keyword(s):  
Dynamic Properties ◽  
Fatigue Analysis ◽  
Management Program ◽  
Measured Data ◽  
Operating Conditions ◽  
Valuable Insight ◽  
Fe Model ◽  
Flow Induced Vibration ◽  
Vibration Measurements

Abstract Certain subsea jumper design features coupled with operating conditions can lead to Flow Induced Vibration (FIV) of subsea jumpers. Excessive FIV can result in accumulation of allowable fatigue damage prior to the end of jumper service life. For this reason, an extensive FIV management program was instated for a large development in the Gulf of Mexico (GOM) where FIV had been observed. The program consisted of in-situ measurement, modeling and analysis. Selected well and flowline jumpers were outfitted with subsea instrumentation for dedicated vibration testing. Finite Element (FE) models were developed for each jumper and refined to match the dynamic properties extracted from the measured data. Fatigue analysis was then carried out using the refined FE model and measured response data. If warranted by the analysis results, action was taken to mitigate the deleterious effects of FIV. Details on modeling and data analysis were published in [5]. Herein, we focus on the overall findings and lessons learned over the duration of the program. The following topics from the program are discussed in detail: 1. In-situ vibration measurement 2. Overall vibration trends with flow rate and lack of correlation of FIV to flow intensity (rho-v-squared); 3. Vibration and fatigue performance of flowline jumpers vs. well jumpers 4. Fatigue analysis conservatism Reliance on screening calculations or predictive FE analysis could lead to overly conservative operational limits or a high degree of fatigue life uncertainty in conditions vulnerable to FIV. It is proposed that in-situ vibration measurements followed by analysis of the measured data in alignment with operating conditions is the best practice to obtain a realistic understanding of subsea jumper integrity to ensure safe and reliable operation of the subsea system. The findings from the FIV management program provide valuable insight for the subsea industry, particularly in the areas of integrity management of in-service subsea jumpers; in-situ instrumentation and vibration measurements and limitations associated with predictive analysis of jumper FIV. If learnings, such as those discussed here, are fed back into design, analysis and monitoring guidelines for subsea equipment, the understanding and management of FIV could be dramatically enhanced compared to the current industry practice.

Seismic Qualification of Piping Systems by Detailed Inelastic Response Analysis: Part 3 — Variation in Elastic-Plastic Analysis Results on Carbon Steel Pipes From the Benchmark Analyses and the Parametric Analysis

2017 ◽  
Author(s):  
Izumi Nakamura ◽  
Akihito Otani ◽  
Masaki Morishita ◽  
Masaki Shiratori ◽  
Tomoyoshi Watakabe ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Evaluation Procedure ◽  
Response Analysis ◽  
Seismic Load ◽  
Inelastic Response ◽  
Elastic Plastic ◽  
Analytical Results ◽  
Plastic Analysis ◽  
Piping Systems ◽  
Parametric Analyses

It is recognized that piping systems used in nuclear power plants have a significant amount of the safety margin, up to the point of boundary failure, even when the input seismic load exceeds the allowable design level. The reason is attributed to the large strength capacity of the piping systems in the plastic region. In order to establish an evaluation procedure, in which the inelastic behavior of piping systems is considered in a rational way, a task group activity under the Japan Society of Mechanical Engineers (JSME) has been conducted. As a deliverable of this activity, a Code Case in the framework of the JSME Nuclear Codes and Standards is now being developed. The Code Case provides the strain-based criteria, an evaluation procedure using the response-spectrum based inelastic analysis, and detailed inelastic response analysis based on a finite element model. For developing the Code Case, inelastic benchmark and parametric analyses of the tests of a pipe element and piping system made of carbon steel were conducted to investigate the variation of the elastic-plastic analyses results. Based on these analytical results, it is assumed that setting the yield stress has a significant influence on the inelastic analytical results, while the work hardening modulus in the bi-linear approximation of the stress-strain curve has little influence. From the results of the parametric analyses, it is confirmed that the variation in the analytical results among the analysts would be reduced by having a unifying analysis procedure. In this paper, the results of the parametric analyses and the variation in the elastic-plastic analysis are discussed.

Two-Dimensional Nonlinear Earthquake Response Analysis of a Bridge-Foundation-Ground System

2008 ◽  
Vol 24 (2) ◽  
pp. 343-386 ◽  
Author(s):  
Yuyi Zhang ◽  
Joel P. Conte ◽  
Zhaohui Yang ◽  
Ahmed Elgamal ◽  
Jacobo Bielak ◽  
...  
Keyword(s):  
Lateral Spreading ◽  
Soil Liquefaction ◽  
Earthquake Response ◽  
Response Analysis ◽  
Fe Model ◽  
Two Dimensional ◽  
Foundation Soil ◽  
Soil Medium ◽  
Surface Plasticity ◽  
Earthquake Response Analysis

This paper presents a two-dimensional advanced nonlinear FE model of an actual bridge, the Humboldt Bay Middle Channel (HBMC) Bridge, and its response to seismic input motions. This computational model is developed in the new structural analysis software framework OpenSees. The foundation soil is included to incorporate soil-foundation-structure interaction effects. Realistic nonlinear constitutive models for cyclic loading are used for the structural (concrete and reinforcing steel) and soil materials. The materials in the various soil layers are modeled using multi-yield-surface plasticity models incorporating liquefaction effects. Lysmer-type absorbing/transmitting boundaries are employed to avoid spurious wave reflections along the boundaries of the computational soil domain. Both procedures and results of earthquake response analysis are presented. The simulation results indicate that the earthquake response of the bridge is significantly affected by inelastic deformations of the supporting soil medium due to lateral spreading induced by soil liquefaction.

Forced Response Sensitivity of a Mistuned Rotor From an Embedded Compressor Stage

2015 ◽  
Author(s):  
Fanny M. Besem ◽  
Robert E. Kielb ◽  
Nicole L. Key
Keyword(s):  
Experimental Data ◽  
Forced Response ◽  
Symmetric System ◽  
Response Analysis ◽  
Cfd Simulations ◽  
Forcing Function ◽  
Wear And Tear ◽  
The Individual ◽  
The Impact ◽  
Interblade Phase Angle

The frequency mistuning that occurs due to manufacturing variations and wear and tear of the blades can have a significant effect on the flutter and forced response behavior of a blade row. Similarly, asymmetries in the aerodynamic or excitation forces can tremendously affect the blade responses. When conducting CFD simulations, all blades are assumed to be tuned (i.e. to have the same natural frequency) and the aerodynamic forces are assumed to be the same on each blade except for a shift in interblade phase angle. The blades are thus predicted to vibrate at the same amplitude. However, when the system is mistuned or when asymmetries are present, some blades can vibrate with a much higher amplitude than the tuned, symmetric system. In this research, we first conduct a deterministic forced response analysis of a mistuned rotor and compare the results to experimental data from a compressor rig. It is shown that tuned CFD results cannot be compared directly with experimental data because of the impact of frequency mistuning on forced response predictions. Moreover, the individual impact of frequency, aerodynamic, and forcing function perturbations on the predictions is assessed, leading to the conclusion that a mistuned system has to be studied probabilistically. Finally, all perturbations are combined and Monte-Carlo simulations are conducted to obtain the range of blade response amplitudes that a designer could expect.

Signal Processing for Operational Modal Analysis of a Jacket-Type Offshore Platform: Sea Test Study

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Xingxian Bao ◽  
Zhihui Liu ◽  
Chen Shi
Keyword(s):  
Noise Reduction ◽  
Modal Analysis ◽  
Measured Data ◽  
Offshore Platform ◽  
Operational Modal Analysis ◽  
Ambient Vibration ◽  
Data Matrix ◽  
Modal Parameters ◽  
Stability Diagrams ◽  
Free Decay

Operational modal analysis (OMA) has been widely used for large structures. However, measured signals are inevitably contaminated with noise and may not be clean enough for identifying the modal parameters with proper accuracy. The traditional methods to estimate modal parameters in noisy situation are usually absorbing the “noise modes” first, and then using the stability diagrams to distinguish the true modes from the “noise modes.” However, it is still difficult to sort out true modes because the “noise modes” will also tend to be stable as the model order increases. This study develops a noise reduction procedure for polyreference complex exponential (PRCE) modal analysis based on ambient vibration responses. In the procedure, natural excitation technique (NExT) is first applied to get free decay responses from measured (noisy) ambient vibration data, and then the noise reduction method based on solving the partially described inverse singular value problem (PDISVP) is implemented to reconstruct a filtered data matrix from the measured data matrix. In our case, the measured data matrix is block Hankel structured, which is constructed based on the free decay responses. The filtered data matrix should maintain the block Hankel structure and be lowered in rank. When the filtered data matrix is obtained, the PRCE method is applied to estimate the modal parameters. The proposed NExT-PDISVP-PRCE scheme is applied to field test of a jacket type offshore platform. Results indicate that the proposed method can improve the accuracy of OMA.

scholarly journals New Design Concept for Bridge Restrainers with Rubber Cushion Considering Dynamic Action: A Preliminary Study

2020 ◽  
Vol 10 (19) ◽  
pp. 6847
Author(s):  
Hiroki Tamai ◽  
Chi Lu ◽  
Yoichi Yuki
Keyword(s):  
Design Concept ◽  
Seismic Retrofitting ◽  
Response Analysis ◽  
Fe Model ◽  
Dynamic Action ◽  
Current Design ◽  
Coupling Dynamic ◽  
Existing Bridges ◽  
Constituent Elements ◽  
Large Earthquakes

A bridge unseating prevention system is a safety system for bridge collapses caused by large earthquakes, beyond the assumption of aseismic design specifications. Presently, the system is generally adopted for newly constructed bridges and the seismic retrofitting of existing bridges. Cable type bridge restrainers are included in the system, and they are expected to prevent superstructures from exceeding the seat length of substructures. Although the bridge restrainer works during an earthquake, it is designed to be static in the current design. In addition, although the constituent elements of bridge restrainers include a rubber cushion to absorb energy during an earthquake, the effect is not included in the design. Thus, the current design lacks the dynamic effects of earthquakes and the cushioning effect of the rubber. Furthermore, in the case of a multi-span bridge, there is no particular decision as to where the restrainers should be placed or what kind of specifications they should have. Therefore, in this paper, a new design concept that considers the dynamic action of the earthquake and the cushioning effect of the rubber is proposed by coupling dynamic response analysis using a frame finite element (FE) model and a simple genetic algorithm (SGA).

Sign in / Sign up

Export Citation Format

Share Document