Damage Detection in Nanofiller-Modified Composites With External Circuitry via Resonant Frequency Shifts

2018 ◽  
Author(s):  
T. N. Tallman
Keyword(s):  
Resonant Frequency ◽  
Damage Detection ◽  
High Frequency ◽  
Carbon Nanofiber ◽  
Piezoresistive Effect ◽  
Frequency Shifts ◽  
Frequency Dependent ◽  
Preliminary Results ◽  
Dependent Behavior ◽  
Electrical Resonance

Conductive nanofiller-modified composites have received a lot of attention from the structural health monitoring (SHM) research community in recent years because these materials are piezoresistive (i.e. they have deformation and damage-dependent electrical conductivity) and are therefore self-sensing. To date, the vast majority of work in this area has utilized direct current (DC) interrogation to identify and/or localize damage. While this approach has been met with much success, it is also well known that nanofiller-modified composites possess frequency-dependent electrical behavior. This behavior can be roughly modeled as a parallel resistor-capacitor circuit. However, much less work has been done to explore the potential this frequency-dependent behavior for damage detection. To this end, the work herein presented covers some preliminary results which leverage high-frequency electrical interrogation for damage detection. More specifically, carbon nanofiber (CNF)/epoxy specimens are produced and connected to an external inductor in both series and parallel configurations. Because the CNF/epoxy electrically behaves like a resistor-capacitor circuit, the inclusion of an inductor enables electrical resonance to be achieved. Changes in resonant frequency are then used for rudimentary damage detection. These preliminary results indicate that the potential of SHM via the piezoresistive effect in nanofiller-modified composites can be considerably expanded by leveraging alternating current (AC) interrogation and resonant frequency principles.

scholarly journals A Displacement Sensor Based on a Normal Mode Helical Antenna

Sensors ◽  
2019 ◽  
Vol 19 (17) ◽  
pp. 3767 ◽  
Author(s):  
Xue ◽  
Yi ◽  
Xie ◽  
Wan ◽  
Ding
Keyword(s):  
Resonant Frequency ◽  
Normal Mode ◽  
High Frequency ◽  
Displacement Sensor ◽  
Helical Antenna ◽  
Frequency Shifts ◽  
High Frequency Structure Simulator ◽  
Resonant Frequency Shift ◽  
Gradient Change ◽  
Applied Displacement

This paper presents a passive displacement sensor based on a normal mode helical antenna. The sensor consists of an external helical antenna and an inserting dielectric rod. First, the perturbation theory is adopted to demonstrate that both the electric intensity and magnetic intensity have a noticeable gradient change within the in-and-out entrance of the helical antenna, which will cause the sensor to experience a resonant frequency shift. This phenomenon was further verified by numerical simulation using the Ansoft high frequency structure simulator (HFSS), and results show the linear correlation between the retrieved resonant frequency and the displacement. Two sets of proposed sensors were fabricated. The experiments validated that the resonant frequency shifts are linearly proportional to the applied displacement, and the sensing range can be adjusted to accommodate the user’s needs.

scholarly journals Patch antenna sensor for wireless ice and frost detection

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ryan Kozak ◽  
Kasra Khorsand ◽  
Telnaz Zarifi ◽  
Kevin Golovin ◽  
Mohammad H. Zarifi
Keyword(s):  
Resonant Frequency ◽  
Patch Antenna ◽  
Wide Band ◽  
Power Lines ◽  
Ice Thickness ◽  
Ice Accretion ◽  
Robust Method ◽  
Frequency Shifts ◽  
Resonant Amplitude ◽  
Recorded Data

AbstractA patch antenna sensor with T-shaped slots operating at 2.378 GHz was developed and investigated for wireless ice and frost detection applications. Detection was performed by monitoring the resonant amplitude and resonant frequency of the transmission coefficient between the antenna sensor and a wide band receiver. This sensor was capable of distinguishing between frost, ice, and water with total shifts in resonant frequency of 32 MHz and 36 MHz in the presence of frost and ice, respectively, when compared to the bare sensor. Additionally, the antenna was sensitive to both ice thickness and the surface area covered in ice displaying resonant frequency shifts of 2 MHz and 8 MHz respectively between 80 and 160 μL of ice. By fitting an exponential function to the recorded data, the freezing rate was also extracted. The analysis within this work distinguishes the antenna sensor as a highly accurate and robust method for wireless ice accretion detection and monitoring. This technology has applications in a variety of industries including the energy sector for detection of ice on wind turbines and power lines.

Study on a Novel MEMS High G Acceleration Sensor

2012 ◽  
Vol 490-495 ◽  
pp. 499-503
Author(s):  
Ping Li ◽  
Yun Bo Shi ◽  
Jun Liu ◽  
Shi Qiao Gao
Keyword(s):  
Resonant Frequency ◽  
Natural Frequency ◽  
Impact Load ◽  
Hopkinson Bar ◽  
Experimental Results ◽  
Structure Parameters ◽  
Acceleration Sensor ◽  
Piezoresistive Effect ◽  
Sensor Structure ◽  
The Impact

This paper presents a novel MEMS high g acceleration sensor based on piezoresistive effect. For the designed sensor structure, the formula of stress, natural frequency and damping was derived in theory, and the resonant frequency can up to 500kHz. After the structure parameters were designed, the sensor was fabricated by the standard processing technology, and the sensitivity was tested by Hopkinson bar. According to the experimental results, the sensitivity of the high g acceleration sensor is 0.125μV/g at the impact load of 164,002g.

Hypersonic Velocity, Absorption and Relaxation in Molten CSNO3

1977 ◽  
Vol 32 (1) ◽  
pp. 57-60 ◽  
Author(s):  
H. E. Gunilla Knape ◽  
Lena M. Torell
Keyword(s):  
Relaxation Time ◽  
High Frequency ◽  
Viscosity Coefficient ◽  
Sound Waves ◽  
Frequency Range ◽  
Ultrasonic Velocities ◽  
Hypersonic Velocity ◽  
Frequency Shifts ◽  
Bulk Viscosity Coefficient ◽  
Good Agreement

Abstract Brillouin spectra of molten CSNO3 were investigated for scattering angles between 40 and 140° and in a temperature interval of 420-520 °C. An Ar+ singlemode laser was used for excitation and the total instrumental width was ~265 MHz. The measured frequency shifts and linewidths of the Brillouin components were used to determine velocities and attenuations of thermal sound waves in the frequency range 2.3-7.0 GHz. A dispersion of 4-5% was found between the present hyper­ sonic velocities and reported ultrasonic velocities. A considerable decrease in attenuation with frequency was observed in the investigated frequency range, with the value at high frequency ap­ proaching the classical attenuation. The results are in good agreement with Mountain's theory of a single relaxation time. The relaxation time of the bulk viscosity coefficient was calculated to 1.2×10-10S.

Thermo-optical switches using coated microsphere resonators

2001 ◽  
Vol 694 ◽  
Author(s):  
C. Tapalian ◽  
J.-P. Laine ◽  
P. A. Lane
Keyword(s):  
Resonant Frequency ◽  
Frequency Shift ◽  
Conjugated Polymer ◽  
Optical Switching ◽  
Optical Switches ◽  
Whispering Gallery Modes ◽  
Pump Light ◽  
Silica Microsphere ◽  
Frequency Shifts ◽  
Whispering Gallery

AbstractWe report optical switching by a silica microsphere optical resonator coated by a conjugated polymer. Microspheres were fabricated by melting the tip of an optical fiber and coated by dipping in a 1 mg/ml toluene solution of poly(2,5-dioctyloxy-1,4-phenylenevinylene) (DOO-PPV). The resonator properties were characterized by evanescently coupling 1.55 µm light propagating along a stripline-pedestal anti-resonant reflecting optical waveguide into optical whispering gallery modes (WGMs). WGM linewidths less than 2 MHz were measured, corresponding to cavity Q > 108. WGM resonant frequency shifts as large as 3.2 GHz were observed when 405 nm pump light with a power density of ~100 mW/cm2 was incident on the microsphere. The time constant of the observed frequency shifts is approximately 0.165 seconds, leading us to attribute the frequency shift to thermo-optic effects. Such a system should be capable of thermo-optically switching at speeds on the order of 10 kHz.

Damage detection on the joint of steel frame through high-frequency admittance signals

2008 ◽  
Author(s):  
Dansheng Wang ◽  
Hongping Zhu ◽  
Huaqiang Zhou ◽  
Haiping Yang
Keyword(s):  
Damage Detection ◽  
High Frequency ◽  
Steel Frame

scholarly journals Nominal and Actual Values of Inductor and Capacitor Parameters at High Frequencies

2019 ◽  
Vol 7 (4) ◽  
pp. 44-53 ◽  
Author(s):  
E. V. Gurov ◽  
S. S. Uvaysov ◽  
A. S. Uvaysova ◽  
S. S. Uvaysova
Keyword(s):  
Resonant Frequency ◽  
High Frequency ◽  
The Self ◽  
Impedance Match ◽  
Analog Filters ◽  
Reactive Component ◽  
High Frequencies ◽  
Coil Inductance ◽  
Parasitic Parameters ◽  
Capacitor Capacitance

Coil inductance and capacitor capacitance depend on overall dimensions, structure, and ambient factors. They do not vary with frequency. Reactive component impedance is determined by inductance or capacitance respectively, if active resistance is not considered. This is true for the frequencies which are significantly lower than the self-resonant frequency of the component. Parasitic parameters contribution increases on approaching the self-resonant frequency. Therefore, the componentʼs actual inductance and actual capacitance on operating frequency are defined. They are provided by manufacturers and differ from the nominal values. The actual values provide more accurate impedance of components near the considered frequency. Significant deviation from the considered frequency can cause impedance mismatch even more than the nominal values can provide. Frequency response of the high-frequency circuits such as analog filters and impedance match networks are determined by components impedance, not the nominal values. Thus, calculated values must be close to the actual values. The purpose of this article is to justify actual values application instead of nominal values.

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