AN EFFICIENT FINITE ELEMENT MODEL FOR ANALYSIS OF SINGLE WALLED BORON NITRIDE NANOTUBE-BASED RESONANT NANOMECHANICAL SENSORS

NANO ◽  
2013 ◽  
Vol 08 (01) ◽  
pp. 1350011 ◽  
Author(s):  
MITESH B. PANCHAL ◽  
S. H. UPADHYAY ◽  
S. P. HARSHA
Keyword(s):  
Finite Element ◽  
Boron Nitride ◽  
Resonant Frequency ◽  
Continuum Mechanics ◽  
Element Model ◽  
Added Mass ◽  
Simulation Approach ◽  
Attached Mass ◽  
Resonant Frequency Shift ◽  
Nanomechanical Sensors

In this paper, the dynamics analysis of single walled boron nitride nanotubes (SWBNNT) as a resonant nanomechanical sensor by using the finite element method has been reported. Molecular structural mechanics-based finite element model (FEM) has been developed by using three-dimensional elastic beams and point masses, such that the proximity of the model to the actual atomic structure of nanotube is significantly retained. Different types of armchair layups of SWBNNTs are considered with cantilevered and bridged end constraints. By implementing the finite element simulation approach, the resonant frequency shift-based mass sensitivity analysis is performed for both types of end constraints for considered armchair form of the SWBNNTs with different aspect ratios. For both types of end constraint, continuum mechanics-based analytical formulations, considering effective wall thickness of nanotubes are used to validate the present FEM-based simulation approach. The intermediate landing position of the added mass is analyzed, considering variations in resonant frequency shifts of the different fundamental modes of vibrations for both types of end constraints. The FEM-based simulation results for both types of end constraints found in good agreement with the continuum mechanics-based analytical results for the aspect ratio of range of 9–15. The mass sensitivity limit of 10-1 zg is achieved for SWBNNT-based resonant nanomechanical sensors. The resonant frequency shift for higher-order fundamental vibrational modes become stable as the attached mass moves away from the fixed ends for particular magnitude of attached mass. The present finite element-based approach is found to be effectual in terms of dealing different atomic structures, boundary conditions and consideration of added mass to analyze the dynamic behavior of the SWBNNT-based resonant nanomechanical sensors.

Doubly-Clamped Single Walled Boron Nitride Nanotube Based Nanomechanical Resonators: A Computational Investigation of Their Behavior

2012 ◽  
Vol 3 (4) ◽  
Author(s):  
Mitesh B. Panchal ◽  
S. H. Upadhyay
Keyword(s):  
Finite Element ◽  
Boron Nitride ◽  
Resonant Frequency ◽  
Frequency Shift ◽  
Dynamic Behavior ◽  
Added Mass ◽  
Boron Nitride Nanotube ◽  
Landing Position ◽  
Nanomechanical Resonators ◽  
Resonant Frequency Shift

This paper illustrates the dynamic behavior of a doubly-clamped single walled boron nitride nanotube (SWBNNT) as a mass sensor. To this end, a 3-dimensional atomistic model based on molecular structural mechanics is developed such that the proximity of the model to the actual atomic structure of the nanotube is significantly retained. Different types of zigzag and armchair layouts of SWBNNTs are considered with doubly-clamped end constraints. Implementing the finite element simulation approach, the resonant frequency shift based analysis is performed for doubly-clamped end-constraints, for an additional nanoscale mass at the middle of the length, and at the intermediate landing position along the length of the nanotube. The effect of the intermediate landing position of added mass on the resonant frequency shift is analyzed by considering excitations of the fundamental modes of vibration. The finite element method (FEM) based simulation results are validated using the continuum mechanics based analytical results, considering the effective wall thickness of the SWBNNT. The present approach is found to be effectual in terms of dealing with different chiralities, boundary conditions, and the consideration of the added mass to analyze the dynamic behavior of the doubly-clamped SWBNNT based nanomechanical resonators.

MASS DETECTION USING SINGLE WALLED BORON NITRIDE NANOTUBE AS A NANOMECHANICAL RESONATOR

NANO ◽  
2012 ◽  
Vol 07 (04) ◽  
pp. 1250029 ◽  
Author(s):  
MITESH B. PANCHAL ◽  
S. H. UPADHYAY ◽  
S. P. HARSHA
Keyword(s):  
Boron Nitride ◽  
Resonant Frequency ◽  
Frequency Shift ◽  
Continuum Mechanics ◽  
Boron Nitride Nanotubes ◽  
Tube Length ◽  
Thin Wall ◽  
Nanomechanical Resonators ◽  
Mass Sensitivity ◽  
Resonant Frequency Shift

The feasibility of the Boron Nitride Nanotubes (BNNTs) as nanomechanical resonators, using continuum mechanics based approach and finite element method (FEM) is illustrated in this paper. Two types of end constraints of single walled boron nitride nanotubes (SWBNNTs), namely cantilevered and bridged are assumed. Analytical formulas based on continuum mechanics are used to examine the mass sensitivity of SWBNNTs considering as a thin wall tubes for both types of end constraints for different lengths and different diameters. The FEM analysis, considering SWBNNT as a transversely anisotropic material is performed and results are compared with the continuum mechanics based approach. The results indicated that the mass sensitivity of SWBNNT-based nanomechanical resonators can reach 10-8fg and a logarithmically linear relationship exists between the resonant frequency and the attached mass, when mass is larger than 10-7fg. The sensitivity of resonant frequency shift to both tube length and diameter has also been demonstrated. It is clear that the change in resonant frequency shift to tube length is more significant than that with the tube diameter and mass sensitivity increases when smaller size nanotube resonators are used in mass sensors. The simulation results based on present FEM found in good agreement with the analytical approach.

Vibration Analysis of Single Walled Boron Nitride Nanotube Based Nanoresonators

2012 ◽  
Vol 3 (3) ◽  
Author(s):  
Mitesh B. Panchal ◽  
S. H. Upadhyay ◽  
S. P. Harsha
Keyword(s):  
Boron Nitride ◽  
Resonant Frequency ◽  
Continuum Mechanics ◽  
Boron Nitride Nanotubes ◽  
Response Analysis ◽  
Published Data ◽  
Boron Nitride Nanotube ◽  
Mass Sensor ◽  
Nanomechanical Resonators ◽  
Mass Sensitivity

In this paper, the vibration response analysis of single walled boron nitride nanotubes (SWBNNTs) treated as thin walled tube has been done using finite element method (FEM). The resonant frequencies of fixed-free SWBNNTs have been investigated. The analysis explores the resonant frequency variations as well as the resonant frequency shift of the SWBNNTs caused by the changes in size of BNNTs in terms of length as well as the attached masses. The performance of cantilevered SWBNNT mass sensor is also analyzed based on continuum mechanics approach and compared with the published data of single walled carbon nanotube (SWCNT) for fixed-free configuration as a mass sensor. As a systematic analysis approach, the simulation results based on FEM are compared with the continuum mechanics based analytical approach and are found to be in good agreement. It is also found that the BNNT cantilever biosensor has better response and sensitivity compared to the CNT as a counterpart. Also, the results indicate that the mass sensitivity of cantilevered boron nitride nanotube nanomechanical resonators can reach 10−23 g and the mass sensitivity increases when smaller size nanomechanical resonators are used in mass sensors.

A Simplified Finite Element for Added Mass and Inertial Coupling in Arrays of Cylinders

1985 ◽  
Vol 107 (2) ◽  
pp. 118-125 ◽  
Author(s):  
R. E. Harris ◽  
M. A. Dokainish ◽  
D. S. Weaver
Keyword(s):  
Finite Element ◽  
Time Integration ◽  
Element Model ◽  
Added Mass ◽  
Cylindrical Structures ◽  
Beam Elements ◽  
Inertial Coupling ◽  
Fundamental Frequencies ◽  
Tube Bundles ◽  
Primary Advantage

A simplified finite element has been developed for modeling the added mass and inertial coupling arising when clusters of cylinders vibrate in a quiescent fluid. The element, which is based on two-dimensional potential flow theory, directly couples two adjacent beam elements representing portions of the adjacent cylindrical structures. The primary advantage of this approach over existing methods is that it does not require the discretization of the surrounding fluid and, therefore, is computationally much more efficient. The fundamental frequencies of tube bundles of various pitch ratios have been predicted using this method and compared with experimental data. Generally, the agreement is good, especially for the bandwidth of fluid coupled natural frequencies. The transient response of tube bundles is also examined using time integration of the finite element model. The beating phenomenon and time decay characteristics exhibited by the experimental bundles under single-tube excitation are well predicted and valuable insights are gained into the measurement of damping in tube bundles.

Modal Analysis and Modeling of a Parallel Kinematic Machine

1999 ◽  
Author(s):  
David S. Hardage ◽  
Gloria J. Wiens
Keyword(s):  
Finite Element ◽  
Resonant Frequency ◽  
Structural Dynamics ◽  
Preliminary Data ◽  
Element Model ◽  
Parallel Kinematic Machine ◽  
Parallel Kinematic ◽  
Machine Configuration ◽  
Stiffness Characteristics ◽  
The Finite Element Model

Abstract This paper presents the results of a mini-modal survey on the Hexel Tornado 2000, a parallel kinematic machine tool located at Sandia National Laboratories, and discusses the finite element model that is used to simulate the structural dynamics of this machine. Preliminary data suggests a dependency of resonant frequency and stiffness characteristics on machine configuration.

Investigation of Vibration Characteristics of the Ligamentous Lumbar Spine Using the Finite Element Approach

1994 ◽  
Vol 116 (4) ◽  
pp. 377-383 ◽  
Author(s):  
Vijay K. Goel ◽  
Hosang Park ◽  
Weizeng Kong
Keyword(s):  
Finite Element ◽  
Resonant Frequency ◽  
Cyclic Load ◽  
Static Load ◽  
Three Dimensional ◽  
Element Model ◽  
Upper Body ◽  
Experimental Investigations ◽  
Flexion Extension

A nonlinear, three-dimensional finite element model of the ligamentous L4-SI segment was developed to analyze the dynamic response of the spine in the absence of damping. The effects of the upper body mass were simulated by including a mass of 40 kg on the L4 vertebral body. The modal analyses of the model indicated a resonant frequency of 17.5 Hz in axial mode and 3.8 Hz in flexion-extension mode. Accordingly, the predicted responses for the cyclic load of −400 ± 40 N applied at four different frequencies (5, 11, 16.5, and 25 Hz) were compared with the corresponding results for axial compressive static loads (−360, and −440 N). As compared to the static load cases, the predicted responses were higher for the cyclic loading. For example, the effect of cyclic load at 11 Hz was to produce significant changes (9.7 – 19.0 percent) in stresses, loads transmitted through the facets, intradiscal pressure (IDP), disk bulge, as compared to the static load predictions. The responses were found to be frequency dependent as well; supporting the in vivo observations of other investigators that the human spine has a resonant frequency. For example, the 11 Hz model (DYN11) compared to the DYN5 model showed an increase in majority of the predicted parameters. The parameters showed an increase with frequency until 17.5 Hz (resonant frequency of the model); thereafter a decrease at 25 Hz. A chronic change in these parameters, especially at the resonant frequency, beyond the “base” values may trigger the bone remodeling process leading to spinal degeneration/disorders associated with chronic vibration exposure. Future directions for extending the present model as a complement to the experimental investigations are also discussed.

Finite element buckling analysis of laminated composite sandwich panels with transversely flexible core carrying attached elastic strip

2012 ◽  
Vol 14 (6) ◽  
pp. 715-733
Author(s):  
Karamat Malekzadeh Fard ◽  
Alireza Sayyidmousavi ◽  
Zouheir Fawaz ◽  
Habiba Bougherara
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Finite Element Model ◽  
Three Dimensional ◽  
Sandwich Panels ◽  
Element Model ◽  
Attached Mass ◽  
Element Analysis ◽  
The Core ◽  
The Face

In this article, a three-dimensional finite element model is proposed to study the effect of distributed attached mass with thickness and stiffness on the buckling instability of sandwich panels with transversely flexible cores. Unlike the previous works in the literature which have made use of unified displacement theories, the present model uses different types of finite elements to model the core and the face sheets. It utilizes shell elements for the face sheets and three-dimensional solid elements for the core which enables the model to account for the transverse flexibility of the structure. The motions of the face sheets and the core as well as the attached mass are related through defining constraint equations between the nodes of their respective finite elements based on the concept of master and slave nodes which is incorporated into the finite element analysis program ANSYS through a user-defined subroutine. The validated finite element model is then used to study the effects of size, thickness, material property, aspect ratio, and the position of the attached mass on the buckling load of a sandwich panel under different combinations of boundary conditions. The results presented in this study have hitherto not been reported in the literature.

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