Dynamic Analysis for a Pipe-in-Pipe Riser System

2012 ◽  
Author(s):  
Yongming Cheng ◽  
Tao Qi ◽  
Xiaoxian Chen
Keyword(s):  
Dynamic Analysis ◽  
Natural Frequencies ◽  
Dynamic Stiffness ◽  
Element Model ◽  
Theoretical Formulation ◽  
Concentric Cylinders ◽  
Effective Dynamic ◽  
Steel Catenary Risers ◽  
Offshore Industry ◽  
Model Approach

A Pipe-In-Pipe (PIP) riser system is widely used in the offshore industry. A typical top tensioned riser system consists of an outer casing, inner casing and tubing. A PIP thermal insulation technology is often used to satisfy stringent insulation requirements and to maintain an acceptable global performance for pipe-in-pipe steel catenary risers. This paper investigates dynamic analysis for a PIP riser system. This paper first presents a theoretical formulation for a PIP riser system coupled with fluids in the annuli and centralizers between pipes. Hydrodynamic forces associated with the viscous fluid in between concentric cylinders are considered. An effective dynamic stiffness matrix method is then developed to evaluate the added mass and damping influence of the fluid on the natural frequencies and the dynamic response of the coupled riser system. The composite model approach is commonly used for modeling concentric PIP riser systems. In reality, however, the riser pipes may contact with the outer pipe at the connectors and centralizers under dynamic loading. This paper then discusses a detailed PIP finite element model to capture the coupling effects of centralizers with gaps. Examples are used to illustrate the dynamic behavior of a PIP riser system. The first example shows the frequency response of a PIP riser coupled through the fluid in the annulus and centralizers distributed longitudinally. The second one represents a PIP riser system coupled through centralizers with gaps. The analysis was performed by using the FEA program ABAQUS.

scholarly journals Dynamic Analysis for an Internally Coupled Fluid/Riser System

2010 ◽  
Author(s):  
Yongming Cheng ◽  
J. Kim Vandiver
Keyword(s):  
Dynamic Analysis ◽  
Natural Frequencies ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Vibration Absorber ◽  
Theoretical Formulation ◽  
System A ◽  
Concentric Cylinders ◽  
Effective Dynamic ◽  
Fluid Coupling

Risers are fluid conduits from subsea equipment to surface floating production platforms. The integrity of a riser system plays a very important role in deepwater developments. A top-tensioned riser generally consists of outer casing, inner casing and tubing. The pipes are coupled either through fluids in the annuli or through intermediate guides (centralizers) or through both. This paper investigates the dynamic analysis for such an internally coupled fluid/ riser system. This paper first presents a theoretical formulation for a general riser system coupled with fluids in the annuli and centralizers between pipes. Hydrodynamic forces associated with the viscous fluid in between concentric cylinders are considered. An effective dynamic stiffness matrix method is then developed to evaluate the added mass and damping influence of the fluid on the natural frequencies and the dynamic response of the coupled riser system. A riser example is used to illustrate the fluid coupling impact on the system’s dynamic performance. The coupling through the fluid and centralizers can be optimally designed such that an inner pipe acts as a vibration absorber to the outer casing.

scholarly journals Riser Dynamic Analysis Using WKB-Based Dynamic Stiffness Method

2012 ◽  
Author(s):  
Yongming Cheng ◽  
J. Kim Vandiver
Keyword(s):  
Dynamic Analysis ◽  
Natural Frequencies ◽  
Shape Function ◽  
Dynamic Stiffness ◽  
Mode Shapes ◽  
Marine Riser ◽  
Theoretical Formulation ◽  
Eigen Value ◽  
Stiffness Method ◽  
Dynamic Stiffness Method

Risers are fluid conduits from subsea equipment to surface floating production platforms. The integrity of a riser system plays a very important role in deepwater developments. Riser dynamic analysis is an important part to the system design. This paper investigates riser dynamic analysis using the WKB-Based dynamic stiffness method. This paper first presents a theoretical formulation of the dynamic stiffness method. It then combines the dynamic stiffness method with the WKB theory, which assumes that the coefficients in the differential equation of motion are slowly varying. The WKB-based dynamic stiffness method is derived and a frequency dependent shape function is expressed implicitly. The Wittrick and Williams (W-W) algorithm is further extended to solve eigen value problem for a general non-uniform marine riser. Examples of non-uniform riser are analyzed and the results show the efficiency of this method. In addition, a pipe-in-pipe riser system is analyzed for natural frequencies and mode shapes using the WKB-based dynamic stiffness method with the W-W algorithm. The characteristic of the mode shapes is described for such a riser system.

scholarly journals An Efficient Spectral Element Model with Electric DOFs for the Static and Dynamic Analysis of a Piezoelectric Bimorph

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Xingjian Dong ◽  
Zhike Peng ◽  
Wenming Zhang ◽  
HongXing Hua ◽  
Guang Meng
Keyword(s):  
Dynamic Analysis ◽  
Electric Potential ◽  
Natural Frequencies ◽  
Single Layer ◽  
Mesh Size ◽  
Element Model ◽  
Spectral Element ◽  
Piezoelectric Bimorph ◽  
Computationally Efficient ◽  
Static And Dynamic Analysis

An efficient spectral element (SE) model for static and dynamic analysis of a piezoelectric bimorph is proposed. It combines an equivalent single layer (ESL) model for the mechanical displacement field with a sublayer approximation for the electric potential. The 2D Gauss-Lobatto-Legendre (GLL) shape functions are used to discretize the displacements and then the governing equation of motion is derived following the standard SE method procedure. It is shown numerically that the present SE model can well predict both the global and local responses such as mechanical displacements, natural frequencies, and the electric potentials across the bimorph thickness. In the case of bimorph sensor application, it is revealed that the distribution of the induced electric potential across the thickness does not affect the global natural frequencies much. Furthermore, the effects of the order of Legendre polynomial and the mesh size on the convergence rate are investigated. Comparison of the present results for a bimorph sensor with those from 3D finite element (FE) simulations establishes that the present SE model is accurate, robust, and computationally efficient.

scholarly journals Dynamic Analysis of Gear and Rack Transmission System

2014 ◽  
Vol 8 (1) ◽  
pp. 662-667
Author(s):  
Xiao Yanjun ◽  
He Lihu ◽  
Zhu Jiayu ◽  
Xiao Yanchun
Keyword(s):  
Finite Element ◽  
Dynamic Analysis ◽  
Bending Strength ◽  
Natural Frequencies ◽  
Equivalent Stress ◽  
Element Model ◽  
Transmission System ◽  
Transient Dynamic Analysis ◽  
Element Analysis ◽  
Transient Dynamic

This paper firstly established a three-dimensional modal of gear and rack transmission system. By using finite element analysis software the model is analyzed and the first six natural frequencies of the gear and rack transmission system are acquired. According to the natural frequencies, actual working speed can be adjusted to avoid resonance. In light of the modal analysis, the transient dynamic finite element model of the gear and rack transmission system is established for the transient dynamic analysis. According to the equivalent stress contour of the gear and rack in contact progress at various times and based on transient dynamic analysis, contact strength and bending strength of the gear are verified and the maximum equivalent stress position is found, providing a theoretical basis for the optimization of the gear and rack.

Determining the Rayleigh damping parameters of flexible pavements for finite element modeling

2021 ◽  
pp. 107754632110267
Author(s):  
Jiandong Huang ◽  
Xin Li ◽  
Jia Zhang ◽  
Yuantian Sun ◽  
Jiaolong Ren
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Natural Frequencies ◽  
Least Squares Method ◽  
Element Model ◽  
Beam Model ◽  
Element Modeling ◽  
Rayleigh Damping ◽  
Damping Matrix

The dynamic analysis has been successfully used to predict the pavement response based on the finite element modeling, during which the stiffness and mass matrices have been established well, whereas the method to determine the damping matrix based on Rayleigh damping is still under development. This article presents a novel method to determine the two parameters of the Rayleigh damping for dynamic modeling in pavement engineering. Based on the idealized shear beam model, a more reasonable method to calculate natural frequencies of different layers is proposed, by which the global damping matrix of the road pavement can be assembled. The least squares method is simplified and used to calculate the frequency-independent damping. The best-fit Rayleigh damping is obtained by only determining the natural frequencies of the two modal. Finite element model and in-situ field test subjected by the same falling weight deflectometer pulse loads are performed to validate the accuracy of this method. Good agreements are noted between simulation and field in-situ results demonstrating that this method can provide a more accurate approach for future finite element modeling and back-calculation.

Modal Analysis and Optimization of Spindle Box of Turn-Milling Center Based on Finite Element Method

2012 ◽  
Vol 226-228 ◽  
pp. 281-284
Author(s):  
Li Da Zhu ◽  
Xiao Bang Wang ◽  
Tiao Biao Yu ◽  
Wan Shan Wang
Keyword(s):  
Finite Element ◽  
Natural Frequencies ◽  
Element Model ◽  
Ansys Software ◽  
Design Requirement ◽  
Design Quality ◽  
Machining Center ◽  
Main Components ◽  
Turn Milling

The dynamic characteristics of machine tool may directly affect its machining capability, which is analyzed to improve the machining precision and efficiency. In this paper, the 3D finite element model of main components turn-milling center is established by using ANSYS software, and then spindle box of turn-milling center is analyzed and optimized; the natural frequencies and vibration models are obtained after analysis, which guarantee the design requirement of the machining center. Therefore it is significant to improve the design quality of machining center by using FEA software in the design process.

DYNAMIC BEHAVIOR OF TELESCOPIC CRANES BOOM

2013 ◽  
Vol 13 (01) ◽  
pp. 1350010 ◽  
Author(s):  
IOANNIS G. RAFTOYIANNIS ◽  
GEORGE T. MICHALTSOS
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Dynamic Behavior ◽  
Analytical Model ◽  
Constant Velocity ◽  
Steel Beam ◽  
Continuum Approach ◽  
Theoretical Formulation ◽  
Modal Superposition ◽  
Superposition Technique

Telescopic cranes are usually steel beam systems carrying a load at the tip while comprising at least one constant and one moving part. In this work, an analytical model suitable for the dynamic analysis of telescopic cranes boom is presented. The system considered herein is composed — without losing generality — of two beams. The first one is a jut-out beam on which a variable in time force is moving with constant velocity and the second one is a cantilever with length varying in time that is subjected to its self-weight and a force at the tip also changing with time. As a result, the eigenfrequencies and modal shapes of the second beam are also varying in time. The theoretical formulation is based on a continuum approach employing the modal superposition technique. Various cases of telescopic cranes boom are studied and the analytical results obtained in this work are tabulated in the form of dynamic response diagrams.

scholarly journals Influence of steel–concrete bond damage on the dynamic stiffness of cracked reinforced concrete beams

2018 ◽  
Vol 21 (13) ◽  
pp. 1977-1989 ◽  
Author(s):  
Tengfei Xu ◽  
Jiantao Huang ◽  
Arnaud Castel ◽  
Renda Zhao ◽  
Cheng Yang
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beam ◽  
Natural Frequencies ◽  
Concrete Beams ◽  
Dynamic Stiffness ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Beams ◽  
Reinforcing Bar ◽  
Sustained Loading ◽  
Inertia Model

In this article, experiments focusing at the influence of steel–concrete bond damage on the dynamic stiffness of cracked reinforced concrete beams are reported. In these experiments, the bond between concrete and reinforcing bar was damaged using appreciate flexural loads. The static stiffness of cracked reinforced concrete beam was assessed using the measured load–deflection response under cycles of loading and unloading, and the dynamic stiffness was analyzed using the measured natural frequencies with and without sustained loading. Average moment of inertia model (Castel et al. model) for cracked reinforced beams by taking into account the respective effect of bending cracks (primary cracks) and the steel–concrete bond damage (interfacial microcracks) was adopted to calculate the static load–deflection response and the natural frequencies of the tested beams. The experimental results and the comparison between measured and calculated natural frequencies show that localized steel–concrete bond damage does not influence remarkably the dynamic stiffness and the natural frequencies both with and without sustained loading applied. Castel et al. model can be used to calculate the dynamic stiffness of cracked reinforced concrete beam by neglecting the effect of interfacial microcracks.

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