On the Modeling of Eigenmodes and Eigenfrequencies of Carbon Graphene Sheets under the Influence of Vacancy Defects

2016 ◽  
Vol 38 ◽  
pp. 101-106
Author(s):  
Seyedeh Alieh Kazemi ◽  
Sadegh Imani Yengejeh ◽  
Andreas Öchsner
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Natural Frequency ◽  
Graphene Sheet ◽  
Mode Shapes ◽  
Graphene Sheets ◽  
Space Frame ◽  
Element Analysis ◽  
Vacancy Defects ◽  
Vibrational Behavior

The vibrational behavior of defected graphene sheets was investigated via finite element analysis. The simulations were carried out for perfect and imperfect nanosheets. This study was conducted to examine the influence of vacant sites on these nanostructures. In the current study, a graphene sheet is considered as a space frame. The natural frequency and corresponding mode shapes of the perfect and defective nanosheets were obtained and compared. Results are presented as diagrams stating the natural frequency of graphene sheets with respect to the amount of vacancy defects. The results indicate that the natural frequency of nanosheets reduced by introducing atomic defects to the configuration of these nanomaterials. Such impurities lower the vibrational stability of graphene sheets.

Investigation of stiffness of small wind turbine blade based on vibration analysis technique

2019 ◽  
Vol 44 (1) ◽  
pp. 49-59
Author(s):  
Nilesh Chandgude ◽  
Nitin Gadhave ◽  
Ganesh Taware ◽  
Nitin Patil
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Wind Turbine ◽  
Natural Frequency ◽  
Vibration Analysis ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Element Analysis ◽  
Finite Element Software ◽  
Small Wind Turbine

In this article, three small wind turbine blades of different materials were manufactured. Finite element analysis was carried out using finite element software ANSYS 14.5 on modeled blades of National Advisory Committee for Aeronautics 4412 airfoil profile. From finite element analysis, first, two flap-wise natural frequencies and mode shapes of three different blades are obtained. Experimental vibration analysis of manufactured blades was carried out using fast Fourier transform analyzer to find the first two flap-wise natural frequencies. Finally, the results obtained from the finite element analysis and experimental test of three blades are compared. Based on vibration analysis, we found that the natural frequency of glass fiber reinforced plastic blade reinforced with aluminum sheet metal (small) strips increases compared with the remaining blades. An increase in the natural frequency indicates an increase in the stiffness of blade.

Study of Passive Vibration Absorbers Attached on Beam Structure

2014 ◽  
Vol 660 ◽  
pp. 511-515 ◽  
Author(s):  
Izzuddin Zaman ◽  
Muhammad Mohamed Salleh ◽  
Maznan Ismon ◽  
Bukhari Manshoor ◽  
Amir Khalid ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Natural Frequency ◽  
Structural Vibration ◽  
Mode Shapes ◽  
Small Scale ◽  
Vibration Absorber ◽  
Vibration Absorbers ◽  
Element Analysis ◽  
Structural Dynamic

Structural vibration is undesirable, wasting energy and possibly leading to excessive deflections and structure and machine’s failure. In order to reduce structural vibration, one of the common way is considering vibration absorber system attach to the structure. In this study, a vibration absorber is developed in a small scale size. The host structure selected for the study is a fixed-fixed ends beam. The effectiveness of vibration absorbers attached to a beam is investigated through experimental study. In prior to experiment, a finite element analysis of Solidworks® and analytical equations of Matlab® are produced in order to determine the structural dynamic response of the beam, such as the natural frequency and mode shapes. The preliminary results of finite element analysis demonstrate that the first five natural frequency of fixed-fixed end beam are 17Hz, 46Hz, 90Hz, 149Hz and 224Hz, and these results are in agreement with the beam’s analytical equations. However, there are slight discrepancies in experiment result due to noise and error occurred during the setup. In the later stage, the experimental works of beam are performed with attached vibration absorber. Result shows that the attachment of vibration absorber produces better outcome, which is about 45% vibration reduction. It is expected that by adding more vibration absorber to the structure, the vibration attenuation can significant.

The Application of Multiple Vibration Neutralizers for Vibration Control in Aircraft

2014 ◽  
Vol 629 ◽  
pp. 191-196 ◽  
Author(s):  
Izzuddin Zaman ◽  
Muhammad Mohamed Salleh ◽  
Bukhari Manshoor ◽  
Amir Khalid ◽  
Sherif Araby
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Vibration Control ◽  
Natural Frequency ◽  
Thin Plate ◽  
Mode Shapes ◽  
Modern Trend ◽  
Small Scale ◽  
Element Analysis ◽  
Structural Dynamic

A current challenge for researchers is the design and implementation of an effective vibration control method that reduces vibration transmission from vehicle structures such as aircraft. This challenge has arisen due to the modern trend of utilizing lightweight thin panels in aircraft structural design, which have the potential to contribute towards significant vibration in the structures. In order to reduce structural vibration, one of the common approaches is considering vibration neutralizer system attached to the structure. In this study, a vibration neutralizer is developed in a small scale size. The effectiveness of attached vibration neutralizers on a thin plate are investigated through experimental study. Prior to the experiment, a finite element analysis of Solidworks® and analytical modelling of Matlab® are produced in order to determine the structural dynamic response of the thin plate such as the natural frequency and mode shapes. The preliminary results of finite element analysis demonstrate that the first four natural frequency of clamped plate are 48Hz, 121Hz, 194Hz and 242Hz, and these results are in agreement with the plate’s analytical equations. However, there are slight discrepancies in the experiment result due to noise and error occurred during the set up. In the later stage, the experimental works of thin plate are performed with attached vibration neutralizer. Result shows that the attachment of vibration neutralizer produces better outcome, which is about 41% vibration reduction. It is expected that by adding more vibration neutralizer to the structure, the vibration attenuation of thin plate can be significant.

scholarly journals Compression and impact characterization of helical and slotted cylinder springs

2014 ◽  
Vol 3 (2) ◽  
pp. 268
Author(s):  
Ahmed Ibrahim Razooqi ◽  
Hani Aziz Ameen ◽  
Kadhim Mijbel Mashloosh
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Natural Frequency ◽  
Transient Response ◽  
Natural Frequencies ◽  
Circular Cross Section ◽  
Mode Shapes ◽  
Helical Spring ◽  
Ansys Software ◽  
Element Analysis

Helical and slotted cylinder springs are indispensable elements in mechanical engineering. This paper investigates helical and slotted cylinder springs subjected to axial loads under static and dynamic conditions. The objective is to determine the stiffness of a circular cross-section helical coil compression spring and slotted cylinder springs with five sizes and dynamic characteristics. A theoretical and finite element models are developed and presented in order to describe the various steps undertaken to calculate the springs stiffnesses. Five cases of the springs geometric are presented. A finite element model was generated using ANSYS software and the stiffness matrix evaluated by applying a load along the springs axis, then calculating the corresponding changes in deformation. The stiffness is obtained by solving the changes of load and deformation. The natural frequencies, mode shapes and transient response of springs are also determined. Finally, a comparison of the stiffnesses are obtained using the theoretical methods and those obtained from the finite element analysis were made and good agreement are evident and it can be found that the stiffness of spring for the slotted cylinder spring is much larger than that for helical spring and the stiffness for slotted cylinder spring increases with the number of slots per section. Natural frequencies, mode shape and transient response of helical spring and slotted cylinder spring have been represented in ANSYS software and results have been compared and it found that the natural frequency has also increased in the same proportion of stiffness because the natural frequency is directly proportional to the stiffness for all the cases that have been studied. Keywords: ANSYS, Finite Element Analysis, Helical Spring, Slotted Cylinder Spring, Stiffness.

Analytical and Numerical Predictions of Thermoelastic Properties of Carbon Single-Walled Nanotubes

Aerospace ◽  
2005 ◽  
Author(s):  
Vinod P. Veedu ◽  
Davood Askari ◽  
Mehrdad N. Ghasemi-Nejhad
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Graphene Sheet ◽  
Effective Properties ◽  
Constitutive Models ◽  
Thermoelastic Properties ◽  
Asymptotic Homogenization ◽  
Element Analysis ◽  
Single Walled Nanotubes ◽  
Numerical Predictions

The objective of this paper is to develop constitutive models to predict thermoelastic properties of carbon single-walled nanotubes using analytical, asymptotic homogenization, and numerical, finite element analysis, methods. In our approach, the graphene sheet is considered as a non-homogeneous network shell layer which has zero material properties in the regions of perforation and whose effective properties are estimated from the solution of the appropriate local problems set on the unit cell of the layer. Our goal is to derive working formulas for the entire complex of the thermoelastic properties of the periodic network. The effective thermoelastic properties of carbon nanotubes were predicted using asymptotic homogenization method. Moreover, in order to verify the results of analytical predictions, a detailed finite element analysis is followed to investigate the thermoelastic response of the unit cells and the entire graphene sheet network.

Dynamic Characteristics and Finite Element Model Updating of Micromachined Torsion Structures

2013 ◽  
Vol 284-287 ◽  
pp. 1831-1835
Author(s):  
Wei Hsin Gau ◽  
Kun Nan Chen ◽  
Yunn Lin Hwang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Speckle Pattern ◽  
Element Model ◽  
Mode Shapes ◽  
Electronic Speckle Pattern Interferometry ◽  
Finite Element Model Updating ◽  
Element Analysis

In this paper, two experimental techniques, Electronic Speckle Pattern Interferometry and Stroboscopic Interferometry, and two different finite element analysis packages are used to measure or to analyze the frequencies and mode shapes of a micromachined, cross-shaped torsion structure. Four sets of modal data are compared and shown having a significant discrepancy in their frequency values, although their mode shapes are quite consistent. Inconsistency in the frequency results due to erroneous inputs of geometrical and material parameters to the finite element analysis can be salvaged by applying the finite element model updating procedure. Two updating cases show that the optimization sequences converge quickly and significant improvements in frequency prediction are achieved. With the inclusion of the thickness parameter, the second case yields a maximum of under 0.4% in frequency difference, and all parameters attain more reliable updated values.

Free Vibration Analysis of PZT Glide Heads

1999 ◽  
Vol 121 (4) ◽  
pp. 984-988 ◽  
Author(s):  
Alex Y. Tsay ◽  
Jin-Hui Ouyang ◽  
C.-P. Roger Ku ◽  
I. Y. Shen ◽  
David Kuo
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Natural Frequencies ◽  
Laser Doppler Vibrometer ◽  
Free Vibration Analysis ◽  
Mode Shapes ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Bonding Length ◽  
Measured Displacement

This paper studies natural frequencies and mode shapes of a glide head with a piezoelectric transducer (PZT) through calibrated experiments and a finite element analysis. In the experiments, the PZT transducer served as an actuator exciting the glide head from 100 kHz to 1.3 MHz, and a laser Doppler vibrometer (LDV) measured displacement of the glide head at the inner or outer rail. The natural frequencies were measured through PZT impedance and frequency response functions from PZT to LDV. In the finite element analysis, the glide head was meshed by brick elements. The finite element results show that there are two types of vibration modes: slider modes and PZT modes. Only the slider modes are important to glide head applications. Moreover, natural frequencies predicted from the finite element analysis agree well with the experimental results within 5% of error. Finally, the finite element analysis identifies four critical slider dimensions whose tolerance will significantly vary the natural frequencies: PZT bonding length, wing thickness, slider thickness, and air bearing recess depth.

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