scholarly journals Experimental Investigation of the Cross-Sensitivity and Size Effects of Polyvinylidene Fluoride Film Sensors on Modal Testing

Sensors ◽  
2012 ◽  
Vol 12 (12) ◽  
pp. 16641-16659 ◽  
Author(s):  
Kuo-Chih Chuang ◽  
Chien-Ching Ma ◽  
Hong-Cin Liou
Keyword(s):  
Experimental Investigation ◽  
Size Effects ◽  
Polyvinylidene Fluoride ◽  
Modal Testing ◽  
Cross Sensitivity ◽  
The Cross

scholarly journals Gravity-Based Characterization of Three-Axis Accelerometers in Terms of Intrinsic Accelerometer Parameters

2017 ◽  
Vol 122 ◽  
Author(s):  
Jon Geist ◽  
Muhammad Yaqub Afridi ◽  
Craig D. McGray ◽  
Michael Gaitan
Keyword(s):  
Gravitational Field ◽  
Coordinate System ◽  
Measurement Errors ◽  
Angle Measurement ◽  
Sensitivity Matrix ◽  
Cross Sensitivity ◽  
Measurement Capability ◽  
Intrinsic Parameters ◽  
The Cross ◽  
Alignment Errors

Cross-sensitivity matrices are used to translate the response of three-axis accelerometers into components of acceleration along the axes of a specified coordinate system. For inertial three-axis accelerometers, this coordinate system is often defined by the axes of a gimbal-based instrument that exposes the device to different acceleration inputs as the gimbal is rotated in the local gravitational field. Therefore, the cross-sensitivity matrix for a given three-axis accelerometer is not unique. Instead, it depends upon the orientation of the device when mounted on the gimbal. We define nine intrinsic parameters of three-axis accelerometers and describe how to measure them directly and how to calculate them from independently determined cross-sensitivity matrices. We propose that comparisons of the intrinsic parameters of three axis accelerometers that were calculated from independently determined cross-sensitivity matrices can be useful for comparisons of the cross-sensitivity-matrix measurement capability of different institutions because the intrinsic parameters will separate the accelerator-gimbal alignment differences among the participating institutions from the purely gimbal-related differences, such as gimbal-axis orthogonality errors, z-axis gravitational-field alignment errors, and angle-setting or angle-measurement errors.

Experimental Investigation of Vortex-Induced Vibrations of a Flexibly Mounted Circular Cylinder in Combined Current and Wave Flows

2021 ◽  
Author(s):  
Pierre-Adrien Opinel ◽  
Narakorn Srinil
Keyword(s):  
Experimental Investigation ◽  
Circular Cylinder ◽  
Cross Flow ◽  
Wave Flow ◽  
Regular Wave ◽  
Regular Waves ◽  
Vortex Induced Vibrations ◽  
Flow Frequency ◽  
The Cross ◽  
Wave Flows

Abstract This paper presents the experimental investigation of vortex-induced vibrations (VIV) of a flexibly mounted circular cylinder in combined current and wave flows. The same experimental setup has previously been used in our previous study (OMAE2020-18161) on VIV in regular waves. The system comprises a pendulum-type vertical cylinder mounted on two-dimensional springs with equal stiffness in in-line and cross-flow directions. The mass ratio of the system is close to 3, the aspect ratio of the tested cylinder based on its submerged length is close to 27, and the damping in still water is around 3.4%. Three current velocities are considered in this study, namely 0.21 m/s, 0.29 m/s and 0.37 m/s, in combination with the generated regular waves. The cylinder motion is recorded using targets and two Qualisys cameras, and the water elevation is measured utilizing a wave probe. The covered ranges of Keulegan-Carpenter number KC are [9.6–35.4], [12.8–40.9] and [16.3–47.8], and the corresponding ranges of reduced velocity Vr are [8–16.3], [10.6–18.4] and [14–20.5] for the cases with current velocity of 0.21 m/s, 0.29 m/s and 0.37 m/s, respectively. The cylinder response amplitudes, trajectories and vibration frequencies are extracted from the recorded motion signals. In all cases the cylinder oscillates primarily at the flow frequency in the in-line direction, and the in-line VIV component additionally appears for the intermediate (0.29 m/s) and high (0.37 m/s) current velocities. The cross-flow oscillation frequency is principally at two or three times the flow frequency in the low current case, similar to what is observed in pure regular waves. For higher current velocities, the cross-flow frequency tends to lock-in with the system natural frequency, as in the steady flow case. The inline and cross-flow cylinder response amplitudes of the combined current and regular wave flow cases are eventually compared with the amplitudes from the pure current and pure regular wave flow cases.

Cross-Sensitivity Characteristics of Instrumented Wheelset Associated With Longitudinal Force and Lateral Contact Position

2021 ◽  
Author(s):  
Takatoshi Hondo ◽  
Takayuki Tanaka ◽  
Shoya Kuniyuki ◽  
Mitsugi Suzuki
Keyword(s):  
Measurement Accuracy ◽  
Contact Point ◽  
Fem Analysis ◽  
Longitudinal Force ◽  
Lateral Position ◽  
Contact Forces ◽  
Load Test ◽  
Static Load Test ◽  
Cross Sensitivity ◽  
The Cross

Abstract It is crucial to grasp wheel-rail contact forces in the evaluation of running safety and curving performance of railway vehicles. To measure the wheel-rail contact forces, instrumented wheelset, which has the strain gauges on the wheel surface, is widely used. The purpose of this research is to increase the measurement accuracy of the wheel-rail contact forces by understanding the detailed characteristics of the instrumented wheelset. Although the various researches on the instrumented wheelset have been carried out to increase the measurement accuracy of wheel-rail contact forces, there are few works considering the longitudinal force and the lateral shift of the wheel-rail contact point. However, sometimes the longitudinal force has a non-negligible influence on the measurement accuracy on the instrumented wheelset. In this paper, the authors clarify the cross-sensitivity characteristics of the instrumented wheelset when the longitudinal force is applied to the various lateral position on the wheel tread through the FEM analysis and the static load test. The authors also propose a method to approximate the cross-sensitivity as an analytical function of the lateral and circumferential contact positions.

scholarly journals Flat Cross-Shaped Piezoelectric Rotary Motor

2020 ◽  
Vol 10 (14) ◽  
pp. 5022
Author(s):  
Andrius Čeponis ◽  
Dalius Mažeika ◽  
Piotr Vasiljev
Keyword(s):  
Experimental Investigation ◽  
Printed Circuit Board ◽  
Rotation Speed ◽  
Circuit Board ◽  
Geometrical Parameters ◽  
Printed Circuit ◽  
Harmonic Signals ◽  
Bending Mode ◽  
The Cross ◽  
Rotary Motor

A numerical and experimental investigation of a flat, cross-shaped piezoelectric rotary motor is presented. The design and configuration of the motor allow it to be mounted directly to the printed circuit board or integrated into the other system where mounting space is limited. The design of the motor is based on the cross-shaped stator with 16 piezo ceramic plates, which are glued on it. The rotor is placed at the center of the stator and consists of two hemispheres, a shaft, and a preloading spring. Special clamping of the stator was developed as well. It consists of four V-shaped beam structures that allow it to rigidly clamp the stator with reduced damping effect to vibrations. The operation principle of the motor is based on the first in-plane bending mode of the cross-shaped stator. The motor excitation is performed through four harmonic signals, which have a phase difference of π/2. A numerical investigation of the motor was conducted to optimize the geometrical parameters of the stator and to analyze the displacement characteristics of the contacting point. The prototype of the motor was made, and the electrical, as well as rotation speed characteristics of the motor, were measured. The results of the experimental investigation showed that the motor is able to provide a maximum rotation speed of 972.62 RPM at 200 Vp-p when the preload force of 22.65 mN was applied.

An Experimental Investigation on Cylinder VIV Trajectories Under Different Model Scale

2014 ◽  
Author(s):  
Zh. Kang ◽  
Yunhe Zhai ◽  
Ruxin Song ◽  
Liping Sun
Keyword(s):  
Experimental Investigation ◽  
Vibration Frequency ◽  
Degrees Of Freedom ◽  
Natural Vibration ◽  
Cross Flow ◽  
Small Scale ◽  
Natural Vibration Frequency ◽  
Test Results ◽  
The Cross ◽  
Initial Research

In this paper, model tests were carried out to investigate two degrees of freedom VIV of horizontally-laid cylinders with diameters of 5cm, 11cm, 20cm and length 120cm and compared their vibration trajectories. The test results showed that the in-line and cross-flow vibration frequency of different scale cylinders demonstrate “multi frequency” phenomenon, that is, the in-line vibration frequency is not only twice but also once or four times as much as the cross-flow vibration frequency in some scale, natural frequency and reduced velocity conditions. Also, the cross-flow multi-frequency vibration phenomenon occurred. The trajectory of the vibration cylinder differentiated from the traditional “8” shape accordingly. The vibration trajectory, especially of small-scale cylinder, changed in most conspicuous manner. Through the initial research and analysis, it was found that in addition to in-line and cross-flow natural vibration frequency and the flow velocity, the shape of cylinders was also one of the main causes leading to different vibration trajectory forms.

scholarly journals Tilted Fiber Bragg Grating Sensor Using Chemical Plating of a Palladium Membrane for the Detection of Hydrogen Leakage

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4478 ◽  
Author(s):  
Jiachen Yu ◽  
Zhenlin Wu ◽  
Xin Yang ◽  
Xiuyou Han ◽  
Mingshan Zhao
Keyword(s):  
Fiber Bragg Grating ◽  
Low Cost ◽  
Hydrogen Sensor ◽  
Bragg Grating ◽  
Wavelength Shift ◽  
Cross Sensitivity ◽  
Chemical Plating ◽  
Palladium Membrane ◽  
Surrounding Refractive Index ◽  
The Cross

A tilted fiber Bragg grating (TFBG) hydrogen sensor coated with a palladium (Pd) membrane by the electroless plating method is proposed in this paper. A uniform layer of Pd metal is fabricated in aqueous solutions by the chemical coating method, which is used as the sensitive element to detect the change of the surrounding refractive index (SRI) caused by hydrogen absorption. The change in SRI causes an unsynchronized change of the cladding modes and the Bragg peak in the TFBG transmission spectrum, thereby eliminating the cross-sensitivity due to membrane expansion and is able to simultaneously monitor the presence of cracks in the pipe, as well as the hydrogen leakage. By subtracting the wavelength shift caused by fiber expansion, the change of SRI, i.e., the information from the H2 level, can be separately obtained. The drifted wavelength is measured for the H2 concentration below the hydrogen explosion limit between 1% and 4%. The chemical-based coating has the advantages of a low cost, a simple operation, and being suitable for coating on long fiber structures. The proposed sensor is able to detect the H2 signal in 5 min at a 1% H2 concentration. The proposed sensor is proved to be able to monitor the hydrogen level without the cross-sensitivity of temperature variation and expansion strains, so could be a good candidate for security applications in industry.

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