A modal analysis of vibration response of a cracked fluid-filled cylindrical shell

2021 ◽  
Vol 91 ◽  
pp. 934-958
Author(s):  
Shuihua Zheng ◽  
Yankun Yu ◽  
Mianzhen Qiu ◽  
Liumin Wang ◽  
Dapeng Tan
Keyword(s):  
Cylindrical Shell ◽  
Modal Analysis ◽  
Vibration Response

Flow-Induced Vibration in Subsea Jumper Subject to Downstream Slug and Ocean Current

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Yaojun Lu ◽  
Chun Liang ◽  
Juan J. Manzano-Ruiz ◽  
Kalyana Janardhanan ◽  
Yeong-Yan Perng
Keyword(s):  
Modal Analysis ◽  
Dominant Role ◽  
Production Equipment ◽  
Vibration Response ◽  
Ocean Current ◽  
Flow Assurance ◽  
Production Flow ◽  
Flow Induced Vibration ◽  
Element Analysis ◽  
Internal Production

This paper presents a multiphysics approach for characterizing flow-induced vibrations (FIVs) in a subsea jumper subject to internal production flow, downstream slug, and ocean current. In the present study, the physical properties of production fluids and associated slugging behavior were characterized by pvtsim and olga programs under real subsea condition. Outcomes of the flow assurance studies were then taken as inputs of a full-scale two-way fluid–structure interaction (FSI) analysis to quantify the vibration response. To prevent onset of resonant risk, a detailed modal analysis has also be carried out to determine the modal shapes and natural frequencies. Such a multiphysics approach actually integrated the best practices currently available in flow assurance (olga and pvtsim), computational fluid dynamics (CFD), finite element analysis (FEA), and modal analysis, and hence provided a comprehensive solution to the FSI involved in a subsea jumper. The corresponding results indicate that both the internal production flow, downstream slugs, and the ocean current would induce vibration response in the subsea jumper. Compared to the vortex-induced vibration (VIV) due to the ocean current and the FIV due to the internal production flow, pressure fluctuation due to the downstream slug plays a dominant role in generating excessive vibration response and potential fatigue failure in the subsea jumper. Although the present study was mainly focused on the subsea jumper, the same approach can be applied to other subsea components, like subsea flowline, subsea riser, and other subsea production equipment.

Reliability of Extracted Modal Parameters by Random Decrement of Acceleration Signatures

2009 ◽  
Author(s):  
Babak Khodabandelou ◽  
Kaveh Abasi ◽  
Masud Asayesh
Keyword(s):  
Numerical Simulation ◽  
Free Vibration ◽  
Modal Analysis ◽  
Correlation Functions ◽  
Vibration Response ◽  
Modal Parameters ◽  
Random Decrement Technique ◽  
Random Decrement ◽  
Free Decay ◽  
Free Vibration Response

Modal parameters provide important information on dynamic properties of structures. In operating condition, since it is difficult to measure input loadings, methods should be applied where don’t require measuring inputs. Such methods which identify modal parameters of structures by measuring their responses are called Operational- or Output Only- Modal Analysis (OMA) techniques. There are many time and frequency domain operational modal analysis techniques. Generally a form of impulse or free vibration response is required to use most of these techniques. However, in practice structures are usually subjected to some immeasurable or unknown random inputs. In these situations Random Decrement (RD) transformation can reduce these responses to equivalent free decay or correlation functions. Therefore, RD technique coupled with those methods, which require a form of impulse or free vibration response offer a valuable tool for identifying the dynamic characteristics of structures from operational or ambient responses. Unfortunately, in the literature there are some constrains on using random decrement signatures. For example by complicated mathematical relations it is shown that random decrement technique is applicable only if the inputs are uncorrelated zero mean Gaussian white noises. In addition, it is proved that only random decrement of displacement and velocity is equivalent to the corresponding free decay responses or correlation functions the random decrement of acceleration response is never equivalent to the corresponding free decay responses or correlation functions. However, there are many papers which have used random decrement of acceleration responses and extracted modal parameters accurately! In this paper it is tried to show simply and clearly whether it is possible to obtain modal parameters from random decrement acceleration signatures or not. To do that, a numerical simulation of a discrete dynamic system with viscous damping is carried out and the results of numerical methods are compared with those come from analytical solution. Numerical simulation is used since it is completely controllable. Finally, it is tried to identify power and the Applicability cases of random decrement method.

scholarly journals A Combined Numerical and Modal Analysis on Vertical Vibration Response of Railway Vehicle

2014 ◽  
Vol 96 ◽  
pp. 310-319 ◽  
Author(s):  
N.F. Nangolo ◽  
J. Soukup ◽  
L. Rychlíková ◽  
J. Skočilas
Keyword(s):  
Modal Analysis ◽  
Vertical Vibration ◽  
Vibration Response ◽  
Railway Vehicle

Residual Vibration Criteria Applied to Multiple Degree of Freedom Cam Followers

1981 ◽  
Vol 103 (4) ◽  
pp. 702-705 ◽  
Author(s):  
J. L. Wiederrich
Keyword(s):  
Modal Analysis ◽  
Vibration Characteristics ◽  
Vibration Response ◽  
Degree Of Freedom ◽  
Operating Speed ◽  
Residual Vibration ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Cam Follower

The vibration characteristics of a cam motion are generally presented by plotting the single degree of freedom residual vibration as a function of normalized operating speed. In this paper it is shown that by applying the methods of modal analysis, these residual vibration characteristics can be extended to the characterization of the vibration response of a multiple degree of freedom cam follower system.

Analytical Modal Analysis of Thin-Film Flat Lenses

2003 ◽  
Author(s):  
L. Moxey ◽  
H. Hamidzadeh
Keyword(s):  
Thin Film ◽  
Analytical Solution ◽  
Dynamic Response ◽  
Modal Analysis ◽  
Closed Form ◽  
Material Properties ◽  
Mathieu Equation ◽  
Free Vibrations ◽  
Vibration Response ◽  
Closed Form Solutions

Dynamics of circular and elliptical thin-film lens are investigated. In particular, linear closed-form solutions for free vibrations of these structures were achieved and modal analysis was performed. The vibration response of the thin film membranes were mathematically modeled using Mathieu equation. Numerical results for various nodal diameters were computed. For the limited case when an elliptical lens becomes circular, an excellent comparison was established with the available analytical solution. Experimental analyses were conducted to determine the effects of various parameters such as material properties, membrane pre strain and the geometry on the dynamic response of these structures. The comparison verified the adequacy of linear solutions to predict the dynamic response of thin film lenses.

scholarly journals Isomap-Based Three-Dimensional Operational Modal Analysis

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Cheng Wang ◽  
Weihua Fu ◽  
Haiyang Huang ◽  
Jianwei Chen
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Three Dimensional ◽  
Transformation Matrix ◽  
Vibration Response ◽  
Operational Modal Analysis ◽  
Modal Parameter ◽  
Matrix Assembly ◽  
Random Decrement Technique ◽  
Low Dimensional

In order to identify the modal parameters of time invariant three-dimensional engineering structures with damping and small nonlinearity, a novel isometric feature mapping (Isomap)-based three-dimensional operational modal analysis (OMA) method is proposed to extract nonlinear features in this paper. Using this Isomap-based OMA method, a low-dimensional embedding matrix is multiplied by a transformation matrix to obtain the original matrix. We find correspondence relationships between the low-dimensional embedding matrix and the modal coordinate response and between the transformation matrix and the modal shapes. From the low-dimensional embedding matrix, the natural frequencies can be determined using a Fourier transform and the damping ratios can be identified by the random decrement technique or natural excitation technique. The modal shapes can be estimated from the Moore–Penrose matrix inverse of the low-dimensional embedding matrix. We also discuss the effects of different parameters (i.e., number of neighbors and matrix assembly) on the results of modal parameter identification. The modal identification results from numerical simulations of the vibration response signals of a cylindrical shell under white noise excitation demonstrate that the proposed method can identify the modal shapes, natural frequencies, and ratios of three-dimensional structures in operational conditions only from the vibration response signals.

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