Measurement method of natural frequencies and tension forces for cables based on elasto-magnetic sensors calibrated by frequencies

High cycle failure of blades and vanes caused by the vibration is one of the major causes reducing the lifetime of turbomachines. For multiblade packets, the failure may occur at vibrations with high frequencies that can reach up to tens of kHz. The experimental modal testing of blades is crucial for the validation of numerical models and for the optimization of turbomachine design. In this paper, the test rig and procedure for measurements of dynamic characteristics of lightweight multiblade packets in wide and high frequency ranges are developed. The measurements are based on a noncontact excitation and noncontact measurement method, which allows the determination of the modal characteristics of the packets with high accuracy in wide frequency ranges. The responses of the multiblade packets are measured using a Scanning Laser Doppler Vibrometry (SLDV), while vibrations are excited by the acoustic excitation technique. Modal tests of the blade packet comprising 18 vane blades connected by shrouds are performed. The measurements are performed within the high frequency range of 0–30 kHz, and the natural frequencies and mode shapes are obtained for first 97 modes. To capture the complex high frequency blade mode shapes, each blade in the packet is scanned over 25 reference points uniformly distributed over the blade concave surface. In order to obtain the high frequency resolution, the frequency range used for the measurements is split into several frequency intervals accordingly to the number of spectral lines available in the used data acquisition system, and for each such interval, the test is performed separately. The finite model of the packet is created, and the numerical modal analysis is performed to compare the calculated natural frequencies and mode shapes with the experimental measurements. The comparison shows the satisfactory with those from finite element analysis. It illustrates the measurement method described in this work is effective and reliable.

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A Novel Non-contact Measurement Method for Current Positioning Based on Magnetic Sensors

10.1109/icpsasia52756.2021.9621425 ◽

2021 ◽

Author(s):

Haoyang Fan ◽

Qi Huang ◽

Zhenyuan Zhang ◽

Shi Jing ◽

Kaiji Liao ◽

...

Keyword(s):

Measurement Method ◽

Magnetic Sensors ◽

Contact Measurement

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Spinning projectile’s attitude measurement using intersection ratio of magnetic sensors

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410016644628 ◽

2016 ◽

Vol 231 (5) ◽

pp. 866-876 ◽

Cited By ~ 3

Author(s):

Jing Yu ◽

Xiongzhu Bu ◽

Chao Xiang ◽

Bo Yang

Keyword(s):

Measurement Method ◽

Inertial Sensors ◽

Detection System ◽

Low Cost ◽

Magnetic Sensor ◽

Magnetic Sensors ◽

Attitude Measurement ◽

Characteristic Ratio ◽

Zero Crossing ◽

Attitude Angle

Concerning on the problem of low measuring precision of the current micro-inertial sensors, a novel attitude measurement method is proposed to dismiss the drift for remarkable attitude error. According to the output of the onboard three-axis magnetic sensor in the process of projectile flight, a low-cost attitude detection system is designed by using the intersection ratio of the sensor. First, the output model of the onboard three-axis magnetic sensor is established. The mathematical relationship between the characteristic ratio of magnetic sensor output and the pitch angle is then derived. Then, the solution and correction algorithm of the attitude angles are studied. Finally, the effectiveness of the attitude measurement method has been validated by carrying out the semi-physical experiments. The experimental results indicate that the error of attitude angles is within ±1° and the attitude angle error of the combined magnetic sensors is not cumulative. Meanwhile, the geomagnetic field strength is dispensable during the whole calculation process. Compared with the “Zero Crossing Method”, the proposed method has shown a nearly two-times higher accuracy and has no limitation of “MAGSONDE window”. What is more, this method proves to be more simple and has a doubled update rate in attitude angle calculation.

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A new mental illness stigma measurement method: Error choice

PsycEXTRA Dataset ◽

10.1037/e683152011-559 ◽

2011 ◽

Author(s):

Patrick Michaels ◽

Patrick Corrigan

Keyword(s):

Mental Illness ◽

Measurement Method ◽

Mental Illness Stigma ◽

Method Error

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Measurement method for eye opening estimation on digital signals

IEE Proceedings F Communications Radar and Signal Processing ◽

10.1049/ip-f-1.1987.0079 ◽

1987 ◽

Vol 134 (5) ◽

pp. 454

Author(s):

M. Kawashima

Keyword(s):

Measurement Method ◽

Digital Signals ◽

Eye Opening

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Analysis of significant measures for thermal conductivity

Izmeritel`naya Tekhnika ◽

10.32446/0368-1025it.2020-3-35-42 ◽

2020 ◽

pp. 35-42

Author(s):

Yuri P. Zarichnyak ◽

Vyacheslav P. Khodunkov

Keyword(s):

Thermal Conductivity ◽

Heat Flux ◽

Surface Heat Flux ◽

Heat Flux Density ◽

Measurement Method ◽

Conductivity Measurement ◽

Surface Heat ◽

Measuring Instrument ◽

New Class ◽

Achievable Accuracy

The analysis of a new class of measuring instrument for heat quantities based on the use of multi-valued measures of heat conductivity of solids. For example, measuring thermal conductivity of solids shown the fallacy of the proposed approach and the illegality of the use of the principle of ambiguity to intensive thermal quantities. As a proof of the error of the approach, the relations for the thermal conductivities of the component elements of a heat pump that implements a multi-valued measure of thermal conductivity are given, and the limiting cases are considered. In two ways, it is established that the thermal conductivity of the specified measure does not depend on the value of the supplied heat flow. It is shown that the declared accuracy of the thermal conductivity measurement method does not correspond to the actual achievable accuracy values and the standard for the unit of surface heat flux density GET 172-2016. The estimation of the currently achievable accuracy of measuring the thermal conductivity of solids is given. The directions of further research and possible solutions to the problem are given.

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