Natural frequencies of a finite‐element model of the cat eardrum

1980 ◽  
Vol 67 (S1) ◽  
pp. S88-S88
Author(s):  
W. Robert ◽  
J. Funnell
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Natural Frequencies ◽  
Element Model

Support-Condition Analyses of Rotating Beams Under Distributed Imbalance Loading

2011 ◽  
Author(s):  
Kai Jokinen ◽  
Erno Keskinen ◽  
Marko Jorkama ◽  
Wolfgang Seemann
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Cross Section ◽  
Cross Sections ◽  
Natural Frequencies ◽  
Element Model ◽  
Mode Shapes ◽  
Constant Cross Section ◽  
Support Condition ◽  
Beam Elements

In roll balancing the behaviour of the roll can be studied either experimentally with trial weights or, if the roll dimensions are known, analytically by forming a model of the roll to solve response to imbalance. Essential focus in roll balancing is to find the correct amount and placing for the balancing mass or masses. If this selection is done analytically the roll model used in calculations has significant effect to the balancing result. In this paper three different analytic methods are compared. In first method the mode shapes of the roll are defined piece wisely. The roll is divided in to five parts having different cross sections, two shafts, two roll ends and a shell tube of the roll. Two boundary conditions are found for both supports of the roll and four combining equations are written to the interfaces of different roll parts. Totally 20 equations are established to solve the natural frequencies and to form the mode shapes of the non-uniform roll. In second model the flexibility of shafts and the stiffness of the roll ends are added to the support stiffness as serial springs and the roll is modelled as a one flexibly supported beam having constant cross section. Finally the responses to imbalance of previous models are compared to finite element model using beam elements. Benefits and limitations of each three model are then discussed.

Hydroelastic Modal Analysis of the Perforated Cylindrical Shell in SMART

2011 ◽  
Author(s):  
Youngin Choi ◽  
Seungho Lim ◽  
Kyoung-Su Park ◽  
No-Cheol Park ◽  
Young-Pil Park ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Element Model ◽  
Mode Shapes ◽  
Steam Generators ◽  
Structure Interaction ◽  
The Finite Element Model ◽  
Reactor Internals

The System-integrated Modular Advanced ReacTor (SMART) developed by KAERI includes components like a core, steam generators, coolant pumps, and a pressurizer inside the reactor vessel. Though the integrated structure improves the safety of the reactor, it can be excited by an earthquake and pump pulsations. It is important to identify dynamic characteristics of the reactor internals considering fluid-structure interaction caused by inner coolant for preventing damage from the excitations. Thus, the finite element model is constructed to identify dynamic characteristics and natural frequencies and mode shapes are extracted from this finite element model.

Thermal Robustness Assessment of a Rigidized Space Inflatable Boom via Experimental Modal Analysis and Finite Element Modeling

2010 ◽  
Author(s):  
Matthew Daly ◽  
Armaghan Salehian ◽  
Alireza Doosthoseini
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Frequency Response Function ◽  
Good Accuracy ◽  
Natural Frequencies ◽  
Beam Theory ◽  
Element Model ◽  
Modal Testing ◽  
Environmental Temperatures ◽  
Robustness Assessment

The following paper presents the results of a thermal robustness assessment of a rigidized space inflatable boom. Modal testing is performed at three different environmental temperatures; spanning a range of 38°C, with the purpose of characterizing dynamic behavior and assessing changes in bending frequencies. Experimental results show that the natural frequencies of the boom shift only marginally within the tested bandwidth. A finite element model is developed in parallel with experiments to determine compatibility with beam theory. The resulting simulation shows that linear beam theory can be used to predict bending frequencies and frequency response function magnitudes with very good accuracy.

Finite Element Model Updating Approach to Damage Identification in Beams Using Particle Swarm Optimization

2008 ◽  
Author(s):  
Mohamed M. Saada ◽  
Mustafa H. Arafa ◽  
Ashraf O. Nassef
Keyword(s):  
Finite Element ◽  
Particle Swarm Optimization ◽  
Finite Element Model ◽  
Natural Frequencies ◽  
Damage Identification ◽  
Model Updating ◽  
Particle Swarm ◽  
Element Model ◽  
Pso Algorithm ◽  
Swarm Optimization

The use of vibration-based techniques in damage identification has recently received considerable attention in many engineering disciplines. While various damage indicators have been proposed in the literature, those relying only on changes in the natural frequencies are quite appealing since these quantities can conveniently be acquired. Nevertheless, the use of natural frequencies in damage identification is faced with many obstacles, including insensitivity and non-uniqueness issues. The aim of this paper is to develop a viable damage identification scheme based only on changes in the natural frequencies and to attempt to overcome the challenges typically encountered. The proposed methodology relies on building a Finite Element Model (FEM) of the structure under investigation. A modified Particle Swarm Optimization (PSO) algorithm is proposed to facilitate updating the FEM in accordance with experimentally-determined natural frequencies in order to predict the damage location and extent. The method is tested on beam structures and was shown to be an effective tool for damage identification.

scholarly journals Application of optimization to change eigenfrequency of a pinion

Mechanik ◽  
2017 ◽  
Vol 90 (7) ◽  
pp. 588-590
Author(s):  
Jacek Stadnicki ◽  
Michał Głąbek
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Final Stage ◽  
Parametric Optimization ◽  
Natural Frequencies ◽  
Element Model ◽  
The Way

During the final stage of designing a pinion which is exploited at different rotational speeds, it is occasionally necessary to offset natural frequencies from frequencies of excitations. The way of solving this problem by means of parametric optimization of the pinion profile, assuming small changes of its shape, is discussed in the paper. The problem is solved using finite element model with regard to monolithic pinion of an aircraft gear.

Modal Analysis and Experimental Research of Marine Gearbox

2014 ◽  
Vol 607 ◽  
pp. 405-408 ◽  
Author(s):  
Wen Liu ◽  
Teng Jiao Lin ◽  
Quan Cheng Peng
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Modal Analysis ◽  
Experimental Research ◽  
Natural Frequencies ◽  
Element Model ◽  
Ansys Software ◽  
Tetrahedral Element ◽  
Spring Element ◽  
Good Agreement

The gear-shaft-bearing-housing coupled finite element model of marine gearbox was established by using the truss element, the spring element and the tetrahedral element. The modal of gearbox was analyzed by using the ANSYS software. Then through the experimental modal analysis, the natural frequencies of gearbox are obtained. Compare the experimental results with the numerical results, it shows good agreement.

Quick Aeromechanical Assessment of Turbine Blades Based on Shell Element Based Models

2014 ◽  
Author(s):  
Suryarghya Chakrabarti ◽  
Letian Wang ◽  
K. M. K. Genghis Khan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Natural Frequencies ◽  
Turbine Blades ◽  
Computation Time ◽  
Shell Element ◽  
Element Model ◽  
Shell Elements ◽  
Barrier Coating ◽  
Order Of Magnitude

A fast finite element model based tool has been developed to calculate the natural frequencies of fundamental modes of cooled gas turbine bladed disk assemblies during conceptual design. The tool uses shell elements to model the airfoil, shank, and disk, and achieves order of magnitude reduction in computation time allowing exploration of a wide design space at the preliminary design stages. The analysis includes prestress effects due to centrifugal loading and approximate temperature loading on the parts. Sensitivity studies are performed to understand the relative impact of design features such as airfoil internal geometry, bond coat, and thermal barrier coating on the system natural frequencies. Critical features are selected which need to be modeled to get an accurate natural frequency estimate. The results obtained are shown to be within 5% of the frequencies obtained from a full-fidelity finite element model. A case study performed on seven blade designs illustrates the use of this tool for quick aeromechanical assessment of a large number of designs.

Vibration Modal Analysis of DTG under Space Environment

2015 ◽  
Vol 757 ◽  
pp. 39-43
Author(s):  
Jian Feng Guo ◽  
Yi Na Feng ◽  
Yi Tao ◽  
Zhong Bao Qin ◽  
Chang Jiang Liu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Modal Analysis ◽  
Natural Frequencies ◽  
Element Model ◽  
Space Environment ◽  
Finite Element Software ◽  
Vibration Modal

Finite element model of dynamic tuned gyroscope (DTG) was founded using finite element software of ANSYS. Natural frequencies and vibration modalities of DTG in cases of both being static and rotating were studied respectively through the method of modal analysis, and also various vibration modalities influence on output of gyroscope was analyzed.

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