scholarly journals Determination Of Wafer And Process Induced Resonant Frequency Variation In Silicon Microdisk-Resonators

2009 ◽  
Author(s):  
William A. Zortman ◽  
Michael R. Watts ◽  
Douglas C. Trotter
Keyword(s):  
Resonant Frequency ◽  
Frequency Variation ◽  
Microdisk Resonators

scholarly journals Enhancement of a New Methodology Based on the Impulse Excitation Technique for the Nondestructive Determination of Local Material Properties in Composite Laminates

2020 ◽  
Vol 11 (1) ◽  
pp. 101
Author(s):  
Carlo Boursier Niutta
Keyword(s):  
Resonant Frequency ◽  
Elastic Properties ◽  
Composite Laminates ◽  
Concentrated Mass ◽  
Modal Shape ◽  
Nondestructive Determination ◽  
Material Orientation ◽  
Impulse Excitation ◽  
Clamping System

A new approach for the nondestructive determination of the elastic properties of composite laminates is presented. The approach represents an improvement of a recently published experimental methodology based on the Impulse Excitation Technique, which allows nondestructively assessing local elastic properties of composite laminates by isolating a region of interest through a proper clamping system. Different measures of the first resonant frequency are obtained by rotating the clamping system with respect to the material orientation. Here, in order to increase the robustness of the inverse problem, which determines the elastic properties from the measured resonant frequencies, information related to the modal shape is retained by considering the effect of an additional concentrated mass on the first resonant frequency. According to the modal shape and the position of the mass, different values of the first resonant frequency are obtained. Here, two positions of the additional mass, i.e., two values of the resonant frequency in addition to the unloaded frequency value, are considered for each material orientation. A Rayleigh–Ritz formulation based on higher order theory is adopted to compute the first resonant frequency of the clamped plate with concentrated mass. The elastic properties are finally determined through an optimization problem that minimizes the discrepancy on the frequency reference values. The proposed approach is validated on several materials taken from the literature. Finally, advantages and possible limitations are discussed.

Energy Resource for a RFID System Based on Dynamic Features of Reddy-Levinson Beam

2020 ◽  
Author(s):  
Alireza Babaei ◽  
Johné Parker ◽  
Paria Moshaver
Keyword(s):  
Resonant Frequency ◽  
Shear Deformation ◽  
Displacement Field ◽  
Energy Harvester ◽  
Frequency Variation ◽  
Low Input ◽  
Piezoelectric Energy ◽  
Rfid System ◽  
Proposed Model ◽  
Thick Beam

Abstract Understanding the effect of design parameters on resonant frequency variation is a critically important aspect of piezoelectric energy harvester device design. As a first step in more accurately investigating the performance of a fixture designed for targeted RFID tag communication that also utilizes an energy harvesting application, this paper analyzes the variations in resonant frequency of a higher-order beam based on Reddy-Levinson theory (RLBT) under rotation effects. A long-term goal of this research is to implement an effective energy harvester on the RFID system. Part of the experimental RFID test fixture can be modeled as a beam (or beam element); thus, understanding the resonance frequency variations due to shear deformation and rotation effects is an important first step in obtaining information about the efficacy of the fixture in serving as an energy harvester. Investigating the performance of a beam also provides valuable information about the maximum power, frequency bandwidth, and tuning ability of the device that can be expected from an analogous energy harvester. For the first time, the resonant frequency variation of a rotating thick beam is investigated. Specifically, RLBT is used to verify the effects of shear deformation upon resonant frequency, and a coupled displacement field is utilized to enable tuning the potential piezoelectric energy harvester to low-input excitations by means of constraining translational and rotational movements of the system based on a linear constraint equation. Navier’s method as an analytical-numerical method is adopted to discretize the continuous system and to find resonant frequencies, respectively. Results reveal the significance of beam thickness and rotation effects of the proposed model for the purpose of minimizing energy usage. Current results are compared and verified numerically with available benchmarks to confirm a satisfactory level of accuracy. The proposed model, which is based on a coupled displacement field, can also be used to design other piezoelectric electro-mechanical-systems; e.g., vibration isolators, and vibration controllers. In other words, in an energy-scavenging system, a fundamental understanding of parameters affecting the resonant frequency can be accomplished through the presented analysis. The proposed model highlights the fact that, by adopting a proper speed factor, tuning the piezoelectric energy harvester to low-input excitations is possible. Additionally, it is observed that the rotation effect on the resonant frequency is more severe than effects of slenderness ratio. Finally, in this paper an improved model is proposed to capture the shear deformation effect, particularly for thick-beam energy harvesters, with the capability of tuning to low-input excitations.

The Influence of Complex Dynamic Phenomena Caused by Wind Action on Behaviour of Transportation Pipelines

2013 ◽  
Vol 837 ◽  
pp. 170-174
Author(s):  
Gheorghe Pintilie
Keyword(s):  
Wind Speed ◽  
Aerodynamic Force ◽  
Mathematical Expression ◽  
Periodic Variation ◽  
Operating Conditions ◽  
Frequency Variation ◽  
Wind Action ◽  
Karman Vortex ◽  
Dynamic Phenomena

The main transportation pipelines are subjected to complex stresses resulting from the nature and state of the transported material, the operating conditions, and the environmental factors and so on. Thus, the stress in the pipe wall is generated and influenced by the pressure, the temperature and the mass of the transported fluid, by the weight of the pipe, the ambient temperature and in certain periods of time by the wind speed. In this paper are presented dynamic phenomena generated by wind flow and their effect on the magistrate transportation pipelines. The content of the paper presents an detailed analysis regarding the regimes in which is developing the force generated by Karman vortex and the situation when resonance phenomena are developed. The study presents a mathematical model that describes the dynamic phenomena generated by the wind action, determining the mathematical expression of the aerodynamic force that act on the normal direction to the wind speed. This force is having a periodic variation, its size and the frequency variation is dependent on the wind speed. Some methods are proposed in order to decrease the wind influence on the lifetime of transportation pipelines. The main results of the study are: determination of the speed range for which the dynamic phenomena have a high influence on the pipeline lifetime; determination of the real conditions that can lead to sharp rises of the pipe deformations; determination of the pipeline lifetime reduction under development of dynamic loads.

scholarly journals 173 DETERMINATION OF TOTAL. RESPIRATORY SYSTEM COMPLIANCE FROM RESONANT FREQUENCY IN INTUBATED SLBJECTS

1990 ◽  
Vol 28 (3) ◽  
pp. 306-306
Author(s):  
Andreas Schulze ◽  
Peter Schaller ◽  
Jürgen Dinger ◽  
Dieter Gmyrek
Keyword(s):  
Resonant Frequency ◽  
Respiratory System ◽  
Respiratory System Compliance

The through transmission impact method for measuring the sound velocity in the compact concrete cubic samples

Metrologiya ◽  
2021 ◽  
pp. 31-40
Author(s):  
V. K. Kachanov ◽  
I. V. Sokolov ◽  
A. A. Samokrutov ◽  
V. G. Shevaldykin ◽  
S. A. Fedorenko ◽  
...  
Keyword(s):  
Surface Wave ◽  
Resonant Frequency ◽  
Sound Velocity ◽  
Measurement Accuracy ◽  
Concrete Durability

A through transmission impact method for measuring the sound velocity in the concrete cubic samples, which are used for determination of the concrete durability, is proposed. It is shown that for elimination of the surface wave influence on the measurement accuracy of the compact cubic sample resonant frequency the impactor and the receiving transducer should be placed on the opposite sides of the cube. Besides in some cases must be used multichannel through transmission impact method.

Sign in / Sign up

Export Citation Format

Share Document