Chinese Journal of Scientific Instrument is 2nd in Mechanical Engineering, Top10.
Supervised by China Association for Science and Technology. Sponsored by China Instrument and Control Society.
Chinese Journal of Scientific Instrument publishes papers with the highest academic level in the field of Chinese instrument and automation, aims to report scientific frontier, research hotspot and research direction, and also supports the creative scientific thought, values the verification of science experiment.
Collected by Ei, CA, SA, JST and CSCD.Impact factor is 2.67.
Editor-in-Chief Zhang Zhonghua
Associate Editor Wang Weiqi, Xu Yunzhong, Wang Xue
In order to improve the measurement accuracy of the embedded time grating angular displacement sensor, starting from the formation mechanism of the sensing signal, the cause of the short period error is analyzed in detail. Through the winding equivalent analysis and excitation signal analysis, it is determined that the main characteristics of the short period error are the first-order error and the quadric error. The source of the first-order error is the zero residual error and the direct current component error, and the source of the quadric error is the excitation-signal quadrature error. Aiming at the compensation of the short period error, an error compensation method based on extreme learning machine is proposed. The model optimal parameters are obtained through training the measured values and real sample values. According to the model parameters, the short period error model is established, which is used to realize the short period error compensation. The experiment result shows that the analysis result of short period error is consistent with the actual characteristic of the sensor error, and with the proposed error compensation method the short period error of the sensor is reduced by about 96%, which is a greatly reduction. The comparison and repetitive experiments show that the accuracy of the proposed method is improved doubly compared with that of the harmonic compensation method, and the error compensation effect is superior. Besides, the proposed method possesses good measurement stability, which has important theoretical and practical significance for improving the measurement accuracy of the embedded time grating angular displacement sensor.
A three-dimensional magnetic dipole model is formulated for the stay cable with 95 mm diameter. The magnetic flux leakage field induced by the broken-wire flaw in the 3D space is analyzed. The spatial distribution of the axial component of the leakage field is highlighted and discussed. The scanning system is constructed to measure the axial component of the leakage field. Experimental results verify the accuracy of the magnetic dipole model on leakage field detection. The threshold method is applied to estimate the effective diffusion angle of the axial component of the leakage field along circumferential direction as ± 6°, which determines that the minimum number of elements in the sensor array is 30. A circular magnetic flux leakage sensor array is developed for the stay cable. With the lift-off of 8 mm, the sensor array can successfully detect multiple surface broken-wire flaws by providing a scanning image to the cable. The effectiveness of the element number in the array on the quality of the scanning image is discussed. This study provides a reference for designing circular magnetic flux leakage sensor array for surface flaw detection in large-diameter stay cables.
During the fast measurement process of measuring the bearing cylindrical roller diameter, the sensor prod deforms due to the applied force produced when the sensor prod approaches the roller, which may reduce the measurement accuracy. Therefore, this paper proposes a contact dynamics research methodology considering the microscopic deformation. Based on Hertz contact theory, nonlinear damping theory, and Coulomb friction theory, a kinematic differential equation between the contact and the roller is established based on the sensor prod deformation during dynamic measurement. Different measurement speed, we obtain position angle, and deformation amount by analyzing the relationship between the normal force and the deformation at the contact point. In addition, the test results from the virtual simulation and the physical prototype experiment show that the roller diameter measurement error is no more than 1 μm. By quantifying the relationship between measurement speed and measurement accuracy, this paper provides a theoretical basis for efficient and accurate contact measurement of the diameter of cylindrical parts in practical engineering applications.
When existing damage imaging algorithms are applied to real complex aeronautical structures, due to the influences of anisotropy of structures, complex boundary reflection and the dispersion characteristics of guided waves, the imaging result is often poor, and the application error is large, or the damage even can not be imaged. To solve the above problems, a structural damage imaging method based on dispersion compensation and path-wave velocity mapping is proposed. Firstly, the dispersion compensation of the scattered wave packet of damage under the influence of anisotropy is applied to optimize the characteristics of guided wave amplitude. Secondly, the problem of large errors of the time of flight caused by structural anisotropy is solved based on path-wave velocity mapping method. The imaging method is validated on the composite structures with stiffeners and openings, and the accuracy of damage imaging is obviously improved.
In system reliability analysis, the correct expression of the uncertain parameters is a prerequisite for stability evaluation. However, the parameter distribution that affects system reliability often lacks strict regularity in engineering. Even the parameters generally obey a certain distribution, they always drift. Information loss is another concern when traditional methods are used to deal with such uncertainties. Therefore, a new method to conduct system reliability analysis under uncertain information is proposed by introducing the probability-box theory. Firstly, the probability-box is used to model uncertain parameters. Secondly, the probability-box model of system reliability is obtained by discretizing each parameter into equal belief values and calculating Cartesian product with the system reliability equation. Finally, the risk zone and the stable zone are divided with zero as boundary, and the system reliability is quantitatively analyzed by integral calculating the area of probability-box. The cantilever beam system is analyzed in the experiments. Experimental results demonstrate that the proposed method is effective and can also improve the accuracy compared with other related approaches.
The piezoelectric film sensor is affected by temperature and the piezoelectric quartz sensor is expensive. Therefore, a fusion design method is achieved by embedding two piezoelectric quartz sensors into four-row piezoelectric film sensors. The equivalent installation model and temperature compensation algorithm of piezoelectric film sensor are established. The piezoelectric quartz sensors are used to perform accurate and real-time temperature compensation for all piezoelectric film sensors. Under the excitation of sinusoidal wave pavement, a quarter vehicle model is selected to conduct weigh-in-motion simulation experiment in MATLAB. In the experiments, the vehicle speed is ranged from 10 km/h to 120 km/h and the environment temperature shifts from 0 to 40 °C. The results show that weighing error mean value of fusion design is less than 0.97%, and accuracy is over 23 times than four-row piezoelectric film sensors, and price is three times lower than four-row piezoelectric quartz sensors. This design can realize high-precision and low-cost detection for vehicle weigh-inmotion, which shows good prospects for engineering applications.
The traditional rotary electro-mechanical converter has the problems of low linearity and small work range of static characteristics. To improve its performance, we have designed a novel rotating proportional electro-mechanical converter. The static characteristics of the rotating proportional electro-mechanical converter are studied by means of magnetic circuit analysis, Maxwell 3D static magnetic field finite element analysis and experimental tests. Meanwhile, a prototype is developed and a series of experiments are conducted. Experimental results indicate that the proportional electro-mechanical converter has a working range from −5° to 5°, and the maximum torque is about ±252 mN·m. In addition, it has a positive magnetic stiffness. The experiment and simulation of torque values are concentrated within the 9.6 mN·m. The relative error is less than 6%, which means that electro-mechanical converter has good repeatability. Furthermore, the nonlinear error of the angle-torque curve is less than 1.5% with a hysteresis of less than 3.5%, which demonstrates that the current–torque curve has good linearity and low hysteresis. It proves that the test results are basically consistent with the simulation results.
