scholarly journals Investigation of approximate mode shape and transition velocity of pipe conveying fluid in failure analysis

2022 ◽  
Vol 14 (1) ◽  
pp. 168781402110724
Author(s):  
Wasiu Adeyemi Oke ◽  
Oluseyi Afolabi Adeyemi ◽  
Ayodeji Olalekan Salau
Keyword(s):  
Failure Analysis ◽  
Mode Shape ◽  
Dynamic Responses ◽  
Mode Shapes ◽  
Pipe Conveying Fluid ◽  
Transition Velocity ◽  
Modal Characteristics ◽  
Pipes Conveying Fluid ◽  
Composite Pipes ◽  
Conveying Fluid

Structures dynamic characteristics and their responses can change due to variations in system parameters. With modal characteristics of the structures, their dynamic responses can be identified. Mode shape remains vital in dynamic analysis of the structures. It can be utilized in failure analysis, and the dynamic interaction between structures and their supports to circumvent abrupt failure. Conversely, unlike empty pipes, the mode shapes for pipes conveying fluid are tough to obtain due to the intricacy of the eigenvectors. Unfortunately, fluid pipes can be found in practice in various engineering applications. Thus, due to their global functions, their dynamic and failure analyses are necessary for monitoring their reliability to avert catastrophic failures. In this work, three techniques for obtaining approximate mode shapes (AMSs) of composite pipes conveying fluid, their transition velocity and relevance in failure analysis were investigated. Hamilton’s principle was employed to model the pipe and discretized using the wavelet-based finite element method. The complex modal characteristics of the composite pipe conveying fluid were obtained by solving the generalized eigenvalue problem and the mode shapes needed for failure analysis were computed. The proposed methods were validated, applied to failure analysis, and some vital results were presented to highlight their effectiveness.

Nonlinear Free Vibration of Spinning Viscoelastic Pipes Conveying Fluid

2018 ◽  
Vol 10 (07) ◽  
pp. 1850076 ◽  
Author(s):  
Feng Liang ◽  
Xiao-Dong Yang ◽  
Wei Zhang ◽  
Ying-Jing Qian
Keyword(s):  
Oil And Gas ◽  
Multiple Scales ◽  
Equations Of Motion ◽  
Drill String ◽  
Mode Shapes ◽  
Flowing Fluid ◽  
Nonlinear Dynamical ◽  
Pipes Conveying Fluid ◽  
Spinning Speed ◽  
Conveying Fluid

Drill strings are one of the most significant rotor components employed in oil and gas exploitation. In this paper, an improved dynamical model of drill-string-like pipes conveying fluid is developed by taking into account the axial spin, fluid–structure interaction (FSI), damping as well as curvature and inertia nonlinearities. The partial differential equations of motion are derived by two sequential Euler angles and the Hamilton principle and then directly handled by the multiple scales method. The nonlinear amplitudes, frequencies and whirling mode shapes are all investigated towards various system parameters to display the nonlinear dynamical characteristics of such a special rotor system coupled with FSI. It is revealed that the nonlinear amplitudes and frequencies are explicitly dependent on the spinning speed, while the flowing fluid mainly contributes to the linear frequencies, and consequently influences the nonlinear amplitudes and frequencies. The FSI effect and axial spin can both improve the forward procession mode and suppress the backward one, while both procession modes will be suppressed by the viscoelastic damping. The pipe will ultimately present a forward as well as decayed whirling motion for the fundamental mode.

Dynamic Behavior of Continuous Cantilevered Pipes Conveying Fluid Near Critical Velocities

1981 ◽  
Vol 48 (4) ◽  
pp. 943-947 ◽  
Author(s):  
J. Rousselet ◽  
G. Herrmann
Keyword(s):  
Partial Differential Equations ◽  
Differential Equations ◽  
Flow Velocity ◽  
Averaging Method ◽  
Nonlinear Partial Differential Equations ◽  
Plane Motion ◽  
Pipe Conveying Fluid ◽  
Pipes Conveying Fluid ◽  
Critical Velocities ◽  
Conveying Fluid

The plane motion of a cantilevered pipe conveying fluid is examined when the flow velocity is in the neighborhood of that generating flutter. In contrast to previous studies, the flow velocity is not prescribed as a constant, but is determined from the laws of motion. We are thus led to a system of two nonlinear partial differential equations which are coupled through the nonlinear terms. The solution is found by the use of the Krylov-Bogoliubov averaging method and the results are discussed indicating the effect of nonlinearities.

Dynamic Stability of Periodic Pipes Conveying Fluid

2013 ◽  
Vol 81 (1) ◽  
Author(s):  
Dianlong Yu ◽  
Michael P. Païdoussis ◽  
Huijie Shen ◽  
Lin Wang
Keyword(s):  
Material Properties ◽  
Unit Length ◽  
Mass Parameter ◽  
High Accuracy ◽  
Pipe Conveying Fluid ◽  
Good Convergence ◽  
System Parameters ◽  
Pipes Conveying Fluid ◽  
The Stability ◽  
Conveying Fluid

In this paper, the stability of a periodic cantilevered pipe conveying fluid is studied theoretically by means of a novel transfer matrix method. This method is first validated by comparing the results to those available in the literature for a uniform pipe, showing that it is capable of high accuracy and displaying good convergence characteristics. Then, the stability of periodic pipes is investigated, with geometric, material-properties periodicity, and a combination of the two, showing that a considerable stabilizing effect may be achieved over different ranges of the mass parameter β (β=mf/(mf+mp), where mf and mp are the fluid and pipe masses per unit length). The effect of other different system parameters is also probed.

Study on the Influence of Gravity Factor on Parametric Resonance of Pipe Conveying Fluid

2013 ◽  
Vol 300-301 ◽  
pp. 1235-1238
Author(s):  
Bing Chen ◽  
Ming Le Deng ◽  
Zhong Jun Yin
Keyword(s):  
Flow Velocity ◽  
Parametric Resonance ◽  
Resonance Region ◽  
Critical Conditions ◽  
Pipe Conveying Fluid ◽  
First Order ◽  
Comparison Results ◽  
Pipes Conveying Fluid ◽  
The One ◽  
Conveying Fluid

The averaging method has been applied to calculate the critical conditions of parametric resonance instability of the first order mode shape of clamped-clamped and pinned-pinned pipes conveying fluid. The influence of gravity factor on parametric resonance of pipe conveying fluid, with different supporting forms and different flow velocity, has been studied based on the comparison results of gravity factor being considered and neglected. It is concluded that gravity factor has a greater influence on parametric resonance region of pinned-pinned pipe than the one of clamped-clamped pipe, and, at a higher flow velocity, gravity factor is more influential to both pinned-pinned pipe and clamped- clamped one.

Characterization of the Modal Characteristics of Structures Operating in Dense Liquid Turbopumps

2017 ◽  
Author(s):  
Joseph Chiu ◽  
Andrew M. Brown
Keyword(s):  
Natural Frequency ◽  
Mode Shape ◽  
Numerical Solutions ◽  
Forced Response ◽  
Modal Testing ◽  
Liquid Oxygen ◽  
Mode Shapes ◽  
Annular Disk ◽  
Modal Characteristics ◽  
Modal Test

It is well-known that the natural frequencies of structures immersed in heavy liquids will decrease due to the fluid “added-mass” effect. This reduction has not been precisely determined, though, with indications that it is in the 20–40% range for water. In contrast, the mode shapes of these structures have always been assumed to be invariant in liquids. Recent modal testing at NASA/Marshall Space Flight Center of turbomachinery inducer blades in liquid oxygen, which has a density slightly greater than water, indicates that the mode shapes change appreciably, though. This paper presents a study that examines and quantifies the change in mode shapes as well as more accurately defines the natural frequency reduction. A literature survey was initially conducted and test-verified analytical solutions for the natural frequency reductions were found for simple geometries, including a rectangular plate and an annular disk. The ANSYS© fluid/structure coupling methodology was then applied to obtain numerical solutions, which compared favorably with the published results. This initial study indicated that mode shape changes only occur for non-symmetric boundary conditions. Techniques learned from this analysis were then applied to the more complex inducer model. ANSYS numerical results for both natural frequency and mode shape compared well with modal test in air and water. A number of parametric studies were also performed to examine the effect of fluid density on the structural modes, reflecting the differing propellants used in rocket engine turbomachinery. Some important findings were that the numerical order of mode shapes changes with density initially, and then with higher densities the mode shapes themselves warp as well. Valuable results from this study include observations on the causes and types of mode shape alteration and an improved prediction for natural frequency reduction in the range of 30–41% for preliminary design. Increased understanding and accurate prediction of these modal characteristics is critical for assessing resonant response, correlating finite element models to modal test, and performing forced response in turbomachinery.

Forced Response Analysis of Pipes Conveying Fluid by Nonlinear Normal Modes Method and Iterative Approach

2017 ◽  
Vol 13 (1) ◽  
Author(s):  
Feng Liang ◽  
Xiao-Dong Yang ◽  
Ying-Jing Qian ◽  
Wei Zhang
Keyword(s):  
Normal Modes ◽  
Harmonic Balance Method ◽  
Nonlinear Normal Modes ◽  
Forced Response ◽  
Dynamic Responses ◽  
Response Analysis ◽  
Iterative Approach ◽  
Pipes Conveying Fluid ◽  
Nonlinear Normal ◽  
Conveying Fluid

The forced vibration of gyroscopic continua is investigated by taking the pipes conveying fluid as an example. The nonlinear normal modes and a numerical iterative approach are used to perform numerical response analysis. The nonlinear nonautonomous governing equations are transformed into a set of pseudo-autonomous ones by using the harmonic balance method. Based on the pseudo-autonomous system, the nonlinear normal modes are constructed by the invariant manifold method on the state space and substituted back into the original discrete equations. By repeating the above mentioned steps, the dynamic responses can be numerically obtained asymptotically using such iterative approach. Quadrature phase difference between the general coordinates is verified for the gyroscopic system and traveling waves instead of standing waves are found in the time-domain complex modal analysis.

scholarly journals A New Method Based on Laplace Transform and Its Application to Stability of Pipe Conveying Fluid

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
H. B. Wen ◽  
Y. R. Yang ◽  
P. Li ◽  
Y. D. Li ◽  
Y. Huang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Present Method ◽  
Natural Frequencies ◽  
Vibration Mode ◽  
Transformation Method ◽  
Critical Flow ◽  
Pipe Conveying Fluid ◽  
Pipes Conveying Fluid ◽  
Conveying Fluid

A new differential transformation method is developed in this paper and is applied for free vibration problem of pipes conveying fluid. The natural frequencies, critical flow velocities, and vibration mode functions of such pipes with several typical boundary conditions are obtained and compared with the results predicted by Galerkin method and finite element method (FEM) and with other results archived. The results show that the present method is of high precision and can serve as an analytical method for the vibration of pipes conveying fluid.

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