Vibration analysis of an aviation engine turbine shaft shield

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Stanisław Noga ◽  
Kaja Maciejowska ◽  
Tomasz Rogalski
Keyword(s):  
Natural Frequencies ◽  
Dynamic Properties ◽  
Normal Modes ◽  
Measuring System ◽  
Mode Shapes ◽  
Modal Assurance Criterion ◽  
Natural Form ◽  
Content Type ◽  
Turbine Shaft ◽  
The Impact

Purpose This paper aims to deal with the problem of vibration in an aircraft engine turbine shaft shield. The physical model of the system under study is inspired by the PZL-10W aviation jet engine shaft shield and is a structure of the profile circular arc. The main goal of the presented research is to develop a modal model of the discussed object. Another task is to determine the impact of the shaft shield damage on the change of dynamic parameters (the values of the natural frequencies and changing of the shape of the corresponding natural forms) of the discussed object. Finally, the task is connected with the calculation of the excitation speeds of the discussed shaft shield’s respective natural frequencies. Design/methodology/approach To realize the main goal finite element method simulation and experimental investigation were conducted. The quality of the achieved models is determined based on the relative error of natural frequencies and the similarity to normal modes established on the basis of the modal assurance criterion (MAC) indicator. The Campbell diagram was used to calculate the excitation speeds of the discussed shaft shield’s respective natural frequencies. Findings The obtained results indicate the changes in the dynamic properties of the shaft shield as a result of its cracking. On the basis of the adopted measurement (MAC indicator), the level of similarity was established between the numerical simulation results and the measurement results for the undamaged shield. Verification of the different mode shapes using the CrossMAC tool is an effective method, which allows comparing of the shape of the natural form and may be helpful in the process of adjusting modal models to the results of experimental tests. Practical implications It is important to note that as a result of using commercial software (ANSYS program) and a commercial measuring system (Bruel and Kjaer), the presented analysis can be attractive for design engineers dealing with the dynamics of aviation systems. Originality/value The paper presents the authors’ original approach to the dynamic analysis of the aviation engine turbine shaft shield, which can be useful for engineers dealing with the issue of vibration in shaft shield systems.

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

scholarly journals Phononic Band Gap and Free Vibration Analysis of Fluid-Conveying Pipes with Periodically Varying Cross-Section

2021 ◽  
Vol 11 (21) ◽  
pp. 10485
Author(s):  
Hao Yu ◽  
Feng Liang ◽  
Yu Qian ◽  
Jun-Jie Gong ◽  
Yao Chen ◽  
...  
Keyword(s):  
Free Vibration ◽  
Band Gap ◽  
Cross Section ◽  
Natural Frequencies ◽  
Free Vibration Analysis ◽  
Critical Parameters ◽  
Mode Shapes ◽  
Beam Model ◽  
The Impact ◽  
Fluid Conveying Pipes

Phononic crystals (PCs) are a novel class of artificial periodic structure, and their band gap (BG) attributes provide a new technical approach for vibration reduction in piping systems. In this paper, the vibration suppression performance and natural properties of fluid-conveying pipes with periodically varying cross-section are investigated. The flexural wave equation of substructure pipes is established based on the classical beam model and traveling wave property. The spectral element method (SEM) is developed for semi-analytical solutions, the accuracy of which is confirmed by comparison with the available literature and the widely used transfer matrix method (TMM). The BG distribution and frequency response of the periodic pipe are attained, and the natural frequencies and mode shapes are also obtained. The effects of some critical parameters are discussed. It is revealed that the BG of the present pipe system is fundamentally induced by the geometrical difference of the substructure cross-section, and it is also related to the substructure length and fluid–structure interaction (FSI). The number of cells does not contribute to the BG region, while it has significant effects on the amplitude attenuation, higher order natural frequencies and mode shapes. The impact of FSI is more evident for the pipes with smaller numbers of cells. Moreover, compared with the conventional TMM, the present SEM is demonstrated more effective for comprehensive analysis of BG characteristics and free vibration of PC dynamical structures.

Natural Frequencies and Normal Modes of a Spinning Timoshenko Beam With General Boundary Conditions

1992 ◽  
Vol 59 (2S) ◽  
pp. S197-S204 ◽  
Author(s):  
Jean Wu-Zheng Zu ◽  
Ray P. S. Han
Keyword(s):  
Boundary Conditions ◽  
Mode Shape ◽  
Timoshenko Beam ◽  
Natural Frequencies ◽  
Normal Modes ◽  
Single Mode ◽  
Mode Shapes ◽  
Simulation Studies ◽  
Classical Boundary ◽  
First Time

A free flexural vibrations of a spinning, finite Timoshenko beam for the six classical boundary conditions are analytically solved and presented for the first time. Expressions for computing natural frequencies and mode shapes are given. Numerical simulation studies show that the simply-supported beam possesses very peculiar free vibration characteristics: There exist two sets of natural frequencies corresponding to each mode shape, and the forward and backward precession mode shapes of each set coincide identically. These phenomena are not observed in beams with the other five types of boundary conditions. In these cases, the forward and backward precessions are different, implying that each natural frequency corresponds to a single mode shape.

Response Characteristics of Serially Connected Semisubmersibles

1999 ◽  
Vol 43 (04) ◽  
pp. 229-240
Author(s):  
H. R. Riggs ◽  
R. C. Ertekin
Keyword(s):  
Energy Loss ◽  
Natural Frequencies ◽  
Normal Modes ◽  
Induced Response ◽  
Linear Wave ◽  
Response Characteristics ◽  
Response Modes ◽  
Wave Induced ◽  
The Impact ◽  
Large Aircraft

One design for a mobile offshore base is to link serially as many as five large semisubmersibles to form a platform long enough to support large aircraft. This paper investigates the linear, wave-induced response characteristics of serially-connected semisubmersibles. A major motivation of this study is to understand more completely the forces required to link semisubmersible modules. The impact of connector strategy and damping on the response, especially the connector forces, is investigated, and the response "modes" which contribute to the connector forces are evaluated in detail. It is shown that the response characteristics can be impacted significantly by the connection strategy, and that connector damping can be a significant source of energy loss when compared to radiation damping. The wet natural frequencies and normal modes are also determined and used to explain the response characteristics of different connection strategies. Although the analyses are based on a specific semisubmersible design, the results provide insight on how other systems of connected semisubmersibles would likely behave.

The Use of Interference Diagrams to Avoid Impeller Resonance: An Application to IGV Design

2009 ◽  
Author(s):  
Marco Ferioli
Keyword(s):  
Centrifugal Compressor ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Common Source ◽  
Operating Speed ◽  
Element Analysis ◽  
Exciting Frequency ◽  
Combine Information ◽  
The Impact

Interference diagrams can be used to avoid the potential excitation of a particular mode of vibration for centrifugal compressor impellers, thus reducing the risk of fatigue failures. Such diagrams are an excellent tool to combine information on impeller natural frequencies and mode shapes, excitation sources and operating speed of the machine on the same graph. Once the impeller design has been finalized in terms of aerodynamic performance, structural assessments and therefore geometry, Finite Element Analysis can be used to predict its natural frequencies and mode shapes (i.e. nodal diameters). Results can therefore be shown on a chart, together with the operating speed range of the machine. The need to plot on a single diagram this whole set of data arises from the mathematical evidence to consider the frequency of vibration together with the mode shape and the shape of the exciting force, while analyzing resonances. Typical Campbell diagrams are unable to provide this information at a glance. A common source of excitation for the first impeller of centrifugal compressors is the IGV set. Inlet Guide Vanes produce an exciting frequency that is directly proportional to the number of vanes N, where N represents also the shape of the excitation. The interference diagram can therefore be used: • to design and optimize the IGV for a new machine; • to choose between two different designs; • to evaluate the impact of a new IGV for the impeller of an existing compressor. A case study will be introduced, in order to show the application of interference diagrams to avoid potentially dangerous resonances between an IGV set and the first impeller during the re-design phase for a centrifugal compressor already in operation.

Random Response of Multi-Segment Beam May Exceed Response of Homogeneous Counterparts by Order of Magnitude

2020 ◽  
Vol 20 (13) ◽  
pp. 2041006
Author(s):  
T. Fang ◽  
I. Elishakoff ◽  
C. Jiang
Keyword(s):  
Random Vibration ◽  
Natural Frequencies ◽  
Dynamic Properties ◽  
Mode Shapes ◽  
Random Response ◽  
Euler Beam ◽  
Mode Method ◽  
Order Of Magnitude ◽  
Engineering Significance ◽  
Normal Mode Method

This paper investigates the dynamic properties of an inhomogeneous, Bernoulli–Euler multi-segment beam composed of different materials. To the best of knowledge of the authors, the problem of random vibrations of beams composing of different chunks of the beams, namely, strong and weak parts, has not been studied in the literature. In this paper, exact solution of the natural frequencies and associated mode shapes of the multi-segment Bernoulli–Euler beam are obtained using Krylov–Duncan functions, followed by free, forced, and random vibration analyses using the normal mode method. Special emphasis is placed on two special configurations of multi-segment beam, namely, the ‘rigid-soft-rigid beam’ (RSR beam) and ‘soft-rigid-soft beam’ (SRS beam) as simplest manifestations of the multi-chunked structures. Some remarkable properties exhibited by the dynamic response of multi-segment beam are demonstrated through this work, which may be of considerable engineering significance, and could not have been anticipated in advance, especially quantitatively.

scholarly journals Identification of Mistuning Characteristics of Bladed Disks From Free Response Data

1998 ◽  
Author(s):  
Marc P. Mignolet ◽  
Alejandro Rivas-Guerra
Keyword(s):  
Dynamic Models ◽  
Natural Frequencies ◽  
Dynamic Properties ◽  
Structural Parameters ◽  
Identification Problem ◽  
Forced Response ◽  
Mode Shapes ◽  
Likelihood Principle ◽  
Bladed Disks ◽  
Block Test

The focus of the present investigation is on the estimation of the dynamic properties, i.e. masses, stiffnesses, natural frequencies, mode shapes and their statistical distributions, of turbomachine blades to be used in the accurate prediction of the forced response of mistuned bladed disks. As input to this process, it is assumed that the lowest natural frequencies of the blades alone have been experimentally measured, for example in a broach block test. Since the number of measurements is always less than the number of unknowns, this problem is indeterminate in nature. Two distinct approaches will be investigated to resolve the shortfall of data. The first one relies on the imposition of as many constraints as needed to insure a unique solution to this identification problem. Specifically, the mode shapes and modal masses of the blades are set to their design/tuned counterparts while the modal stiffnesses are varied from blade-to-blade to match the measured natural frequencies. The second approach, based on the maximum likelihood principle, yields estimates of all the structural parameters of the blades through the minimization of a specified “cost function”. The accuracy of these two techniques in predicting the forced response of mistuned bladed disks will be assessed on simple dynamic models of the blades.

Dynamic Characteristics of Tsing Ma Suspension Bridge

1996 ◽  
Vol 1541 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Siu Kui Au ◽  
Neil Mickleborough ◽  
Paul N. Roschke
Keyword(s):  
Analytical Solutions ◽  
Bridge Deck ◽  
Natural Frequencies ◽  
Dynamic Properties ◽  
Suspension Bridge ◽  
Mode Shapes ◽  
Out Of Plane ◽  
Quantitative Results ◽  
Suspension Cable ◽  
Bending Modes

Numerical simulation was carried out to determine the dynamic properties of the Tsing Ma Suspension Bridge. Both the structure as a whole and individual subcomponents were modeled. Classical analytical solutions for simplified models from the available literature were compared with the results obtained from a finite-element code. Quantitative results for static deflection, natural frequencies, and mode shapes were compared with analytical solutions from linear theory. Out-of-plane modes were shown to be dominant. For in-plane antisymmetric and symmetric bending modes, in which the suspension cable and bridge deck vibrate in the same direction, the natural frequency of the main span of the bridge is determined to be approximately equal to the square root of the sum of the squares of the frequencies of the cable and bridge deck.

scholarly journals Overcoming Effects from Environmental Temperature on the Natural Frequencies of Cable-strut Structures

2020 ◽  
pp. 22-30
Author(s):  
Nasseradeen Ashwear ◽  
Haithem Elderrat ◽  
Mahmud A. Eljaarani
Keyword(s):  
Genetic Algorithm ◽  
Health Monitoring ◽  
Optimization Problem ◽  
Environmental Temperature ◽  
Natural Frequencies ◽  
Dynamic Properties ◽  
Environmental Variable ◽  
Mode Shapes ◽  
Stress Vector ◽  
Temperature Changes

The changes in dynamic properties such as natural frequencies and mode shapes are used in vibration health monitoring as tools for assessing the structures health status. They are, however, also affected by environmental conditions like wind, humidity and temperature changes. Of particular importance is the change of the environmental temperature, and it is the most commonly considered environmental variable that influences the vibration health monitoring algorithms. This paper discusses how cable-strut structures can be designed such that their first natural frequency is less sensitive to the temperature changes. The optimization problem is solved by using a genetic algorithm. The level of pre-stress can be regulated to achieve the solution, particularly when a symmetric self-stress vector is chosen.

scholarly journals Linear Finite Element Modeling of Joined Structures With Riveted Connections

2020 ◽  
Vol 142 (2) ◽  
Author(s):  
J. S. Kim ◽  
Y. F. Xu ◽  
W. D. Zhu
Keyword(s):  
Finite Element ◽  
Natural Frequencies ◽  
Modeling Method ◽  
Test Structure ◽  
Mode Shapes ◽  
Fe Model ◽  
Fe Modeling ◽  
Engineering Structures ◽  
Modal Assurance Criterion ◽  
Linear Finite Element

Abstract Riveted connections are widely used to join basic components, such as beams and panels, for engineering structures. However, accurately modeling joined structures with riveted connections can be a challenging task. In this work, an accurate linear finite element (FE) modeling method is proposed for joined structures with riveted connections to estimate modal parameters in a predictive manner. The proposed FE modeling method consists of two steps. The first step is to develop nonlinear FE models that simulate riveting processes of solid rivets. The second step is to develop a linear FE model of a joined structure with the riveted connections simulated in the first step. The riveted connections are modeled using solid cylinders with dimensions and material properties obtained from the nonlinear FE models in the first step. An experimental investigation was conducted to study accuracy of the proposed linear FE modeling method. A joined structure with six riveted connections was prepared and tested. A linearity investigation was conducted to validate that the test structure could be considered to be linear. A linear FE model of the test structure was constructed using the proposed method. Natural frequencies and corresponding mode shapes of the test structure were measured and compared with those from the linear FE model. The maximum difference of the natural frequencies was 1.63% for the first 23 out-of-plane elastic modes, and modal assurance criterion values for the corresponding mode shapes were all over 95%, which indicates high accuracy of the proposed linear FE modeling method.

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