scholarly journals Mode Localization and Eigenfrequency Curve Veerings of Two Overhanged Beams

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 324
Author(s):  
Yin Zhang ◽  
Yuri Petrov ◽  
Ya-pu Zhao
Keyword(s):  
Mechanical Properties ◽  
Complex Dynamics ◽  
Computational Results ◽  
Mass Sensing ◽  
Mode Localization ◽  
Mode Splitting ◽  
Variation Patterns ◽  
Numerical Discretization ◽  
Discretization Procedure

Overhang provides a simple but effective way of coupling (sub)structures, which has been widely adopted in the applications of optomechanics, electromechanics, mass sensing resonators, etc. Despite its simplicity, an overhanging structure demonstrates rich and complex dynamics such as mode splitting, localization and eigenfrequency veering. When an eigenfrequency veering occurs, two eigenfrequencies are very close to each other, and the error associated with the numerical discretization procedure can lead to wrong and unphysical computational results. A method of computing the eigenfrequency of two overhanging beams, which involves no numerical discretization procedure, is analytically derived. Based on the method, the mode localization and eigenfrequency veering of the overhanging beams are systematically studied and their variation patterns are summarized. The effects of the overhang geometry and beam mechanical properties on the eigenfrequency veering are also identified.

Mode Localization in Two Coupled Nearly Identical MEMS Cantilevers for Mass Sensing

2019 ◽  
Author(s):  
Toky Rabenimanana ◽  
Vincent Walter ◽  
Najib Kacem ◽  
Patrice Le Moal ◽  
Gilles Bourbon ◽  
...  
Keyword(s):  
Amplitude Ratio ◽  
Actuation Voltage ◽  
Beam Theory ◽  
Mass Detection ◽  
Mass Sensing ◽  
Experimental Frequency ◽  
Mode Localization ◽  
Dc Voltage ◽  
Geometrical Imperfections ◽  
Mems Cantilevers

Abstract This paper investigates the mass sensing in a mode-localized sensor composed of two weakly coupled MEMS cantilevers with lengths 98μm and 100μm. The two resonators are connected by a coupling beam near the fixed end, and the shortest cantilever is electrostatically actuated with a combined AC-DC voltage. The DC actuation voltage is tuned to compensate the length difference and geometrical imperfections in order to dynamically equilibrate the system. An analytical model of the device using the Euler Bernoulli beam theory is presented and the required DC voltage to reach the balanced state is used. A mass perturbation is then added on the long cantilever and the eigenstate shifts and amplitude ratios in each mode are calculated for different couplings. Results show that the amplitude ratio of the second mode is the best output metric for the mass detection. For the validation of the model, an experimental investigation is carried out by using devices fabricated with the Multi-User MEMS Processes. Three different couplings are considered and the long cantilever is designed with a mass attached at its end. Instead of adding a mass on the device, we remove this part with a probe to introduce the perturbation. When the mass is removed, the experimental frequency responses of the device show localized vibrations, which are in good agreement with the theoretical results.

Defect-Induced Mechanical Mode Splitting in Carbon Nanotube Resonators

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Ajit K. Vallabhaneni ◽  
Jeffrey F. Rhoads ◽  
Jayathi Y. Murthy ◽  
Xiulin Ruan
Keyword(s):  
Carbon Nanotube ◽  
Md Simulations ◽  
Resonant Mode ◽  
Mass Sensing ◽  
Response Characteristics ◽  
Future Design ◽  
Mode Splitting ◽  
Design Paradigm ◽  
The Impact ◽  
Current Device

This work examines the impact of defects on the resonant response of single-wall carbon nanotube (CNT) resonators using classical molecular dynamics (MD) simulations. The work demonstrates that the presence of defects in CNTs leads to appreciable resonant mode splitting. A dimensionless parameter has been introduced to quantify this phenomenon. It is observed that increasing the degree of asymmetry in the system generally increases the magnitude of splitting. Given the centrality of single-peak Lorentzian frequency responses in the current device design paradigm, which is utilized in applications such as resonant mass sensing, the non-Lorentzian response characteristics of imperfect devices could present both opportunities and challenges in the future design and development of resonant nanosystems.

A Novel Thermal Piezoresistive Coupled Resonator Implementing Mode Localization for Mass Sensing

2020 ◽  
Author(s):  
Shashwat Bhattacharya ◽  
Jyoti Satija ◽  
Shyam Trivedi ◽  
Sheng-Shian Li
Keyword(s):  
Mass Sensing ◽  
Mode Localization ◽  
Coupled Resonator

scholarly journals Determination of elastic constants of functionalized graphene-based epoxy nanocomposites: A molecular modeling and MD simulation study

2021 ◽  
Author(s):  
Aman Yadav ◽  
Amit Kumar ◽  
Kamal Sharma
Keyword(s):  
Mechanical Properties ◽  
Md Simulation ◽  
Poisson Ratio ◽  
Md Simulations ◽  
Computational Results ◽  
Functionalized Graphene ◽  
Epoxy Nanocomposites ◽  
Material Studio ◽  
Simulation Results

Abstract The effect of carboxyl (–COOH) functionalized graphene (FG) on the mechanical properties of its epoxy-based nanocomposites has been investigated by Molecular Dynamics (MD) simulations. Simulations cells of nanocomposites with varying wt% of FG (1, 2 & 3 wt%) were constructed using Material Studio 6.0. Obtained MD simulation results show improved mechanical properties such as elastic modulus, bulk modulus, shear modulus, and the Poisson ratio of the FG/epoxy nanocomposites than that of pure epoxy. Moreover, the computational results of nanocomposites have also been validated well with existing experimental data. Therefore, the current MD simulation shows a decent computational sign for the existing experimental and simulation outcomes on mechanical properties of FG/epoxy nanocomposites.

The assessment of carbon nanotube (CNT) geometry on the mechanical properties of epoxy nanocomposites

2020 ◽  
pp. 2050005
Author(s):  
O. Aluko ◽  
S. Gowtham ◽  
G. M. Odegard
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotube ◽  
Dynamics Simulation ◽  
Computational Results ◽  
Reactive Force ◽  
Elastic Parameters ◽  
Epoxy Nanocomposites ◽  
Single Walled Carbon Nanotube ◽  
Geometric Effect ◽  
Mechanical Performances

The geometric effect of single-walled carbon nanotube (CNT) on mechanical performances of epoxy nanocomposites was investigated under different loading conditions. The reactive force field (ReaxFF) and optimum liquid potential simulator (OPLS) were used in the computational molecular dynamics simulation. The analysis comprises the methodology employed to model the equilibrated structures of CNT/epoxy nanocomposites and characterizes elastic parameters of the structures. The computational results showed that the chirality of the CNTs affects the mechanical performances of the nanocomposites.

scholarly journals Ultrasensitive mass sensing using mode localization in coupled microcantilevers

2006 ◽  
Vol 88 (25) ◽  
pp. 254102 ◽  
Author(s):  
Matthew Spletzer ◽  
Arvind Raman ◽  
Alexander Q. Wu ◽  
Xianfan Xu ◽  
Ron Reifenberger
Keyword(s):  
Mass Sensing ◽  
Mode Localization

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

Effects of cooling rate on the mechanical properties of dual phase treated vanadium steels

1983 ◽  
Vol 41 ◽  
pp. 220-221
Author(s):  
L.J. Chen ◽  
H.C. Cheng ◽  
J.R. Gong ◽  
J.G. Yang
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Automobile Industry ◽  
High Strength ◽  
Weight Percent ◽  
Low Alloy Steels ◽  
Dual Phase ◽  
Resource Requirement ◽  
Alloy Steels ◽  
Potential Weight

For fuel savings as well as energy and resource requirement, high strength low alloy steels (HSLA) are of particular interest to automobile industry because of the potential weight reduction which can be achieved by using thinner section of these steels to carry the same load and thus to improve the fuel mileage. Dual phase treatment has been utilized to obtain superior strength and ductility combinations compared to the HSLA of identical composition. Recently, cooling rate following heat treatment was found to be important to the tensile properties of the dual phase steels. In this paper, we report the results of the investigation of cooling rate on the microstructures and mechanical properties of several vanadium HSLA steels.The steels with composition (in weight percent) listed below were supplied by China Steel Corporation: 1. low V steel (0.11C, 0.65Si, 1.63Mn, 0.015P, 0.008S, 0.084Aℓ, 0.004V), 2. 0.059V steel (0.13C, 0.62S1, 1.59Mn, 0.012P, 0.008S, 0.065Aℓ, 0.059V), 3. 0.10V steel (0.11C, 0.58Si, 1.58Mn, 0.017P, 0.008S, 0.068Aℓ, 0.10V).

Lattice Imaging of Grain Boundaries in Ceramics

1977 ◽  
Vol 35 ◽  
pp. 114-115
Author(s):  
D. R. Clarke ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
High Temperature Strength ◽  
Current Interest ◽  
Lattice Imaging ◽  
Special Significance ◽  
Structural Applications ◽  
Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

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