• Volume 43,Issue 12,2020 Table of Contents
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    • Transmission error analysis of cycloidal pinwheel based on multi-factor comprehensive effect

      2020, 43(12):1-12. DOI: 10.11835/j.issn.1000-582X.2020.12.001

      Abstract (729) HTML (1170) PDF 1.72 M (1321) Comment (0) Favorites

      Abstract:Tooth profile modification and manufacturing error of cycloidal gear are the key factors that affect the transmission accuracy of cycloidal pinwheel. In order to analyze the transmission error of the cycloid gear under the multi-factor comprehensive effect, based on the theory of gearing and coordinate transformation, an error analysis model of the cycloidal pinwheel meshing pair under the comprehensive effect of multiple factors was obtained by constructing the tooth profile equation of the cycloid gear with the comprehensive factors such as tooth profile modification, machining error and assembly error taken into consideration. The model can be used to analyze and calculate the combined transmission errors of the cycloid pin gear under the comprehensive effects of tooth profile modification, machining and assembly errors. The influences of various error factors and multiple factors on the transmission error were analyzed. The results show that the cumulative pitch error has the greatest influence on the transmission error, followed by cycloidal profile error and assembly error; the pin radius error and the pin position radius error have the least influence on the transmission error.

    • Optimization of the jounce bumper for suspension shock absorbers

      2020, 43(12):13-22. DOI: 10.11835/j.issn.1000-582X.2020.12.002

      Abstract (765) HTML (1246) PDF 1.53 M (1664) Comment (0) Favorites

      Abstract:The jounce bumper is an important part in the suspension system. Reasonable design of its structure can effectively improve the NVH(noise, vibration and harshness) of the car. With the structure parameters of the jounce bumper as design variables, the finite element calculation model was used to calculate the performance of the jounce bumper under different parameter combinations, and then a response surface proxy model for the jounce bumper performance calculation was established. The size requirement of the jounce bumper was taken as the design variable and the optimal performance index of the jounce bumper as the objective function to optimize the proxy model by the genetic algorithm. The results show that the performance data of the jounce bumper calculated by the finite element model is basically consistent with that of the physical test, and the jounce bumper optimized by the proposed method has better performance.

    • Analysis of bearing characteristics of differential planetary roller screw

      2020, 43(12):23-32. DOI: 10.11835/j.issn.1000-582X.2020.001

      Abstract (622) HTML (1762) PDF 1.38 M (1297) Comment (0) Favorites

      Abstract:The analysis of bearing characteristics of differential planetary roller screw is carried out based on space meshing theory and Hertz contact theory. Taking into consideration the influence of contact position change caused by the initial meshing point offset between the roller and the screw on the bearing characteristics, the spatial meshing geometry model of the differential planetary roller screw is established, and the meshing point position and principal curvature of the roller and the screw are solved by numerical method. Furthermore, the single roller screw tooth surface accurate load distribution and carrying capacity calculation geometric model are deduced. The calculation results of the model are compared with those of direct stiffness method and the correctness of the presented method is verified. The effects of tooth angle, screw pitch, the number of threads of the roller, and elastic modulus ratio of screw and roller material on the load distribution and bearing capacity of differential planetary roller have been systematically analyzed.

    • Fault state identification method based on fault sensitive components and improved KNNC

      2020, 43(12):33-40. DOI: 10.11835/j.issn.1000-582X.2020.002

      Abstract (403) HTML (714) PDF 1.45 M (885) Comment (0) Favorites

      Abstract:To solve the problem of sensitive feature extraction from the non-stationary and nonlinear vibration signals of rolling bearing, local mean decomposition (LMD) was carried out. and the time/frequency domain features were extracted from the sensitive fault components quantified by the correlation coefficient method. Then, the feature sets of different faults states were established and used to train the state classifier. In order to achieve the higher accuracy of bearing fault states identification, an improved K-nearest neighbor classifier (KNNC) algorithm based on dichotomy K-means clustering was proposed, in which the big training samples were simplified, and the bad samples and interference points were effectively removed. Finally, the effectiveness of the method was verified through diagnostic analysis of experimental data of bearings.

    • Influence of vortex generator on the aerodynamic drag reduction characteristics of heavy truck

      2020, 43(12):41-58. DOI: 10.11835/j.issn.1000-582X.2020.12.005

      Abstract (520) HTML (1168) PDF 16.59 M (1040) Comment (0) Favorites

      Abstract:To understand the influence of the vortex generator on the aerodynamic drag reduction characteristics of heavy-duty trucks, a Chinese heavy-duty truck was taken as the research object to study the influence of the shape, arrangement position, height and gap ratio of the vortex generator on drag reduction effect of the truck based on the numerical simulation of computational fluid dynamics. The reason for drag reduction was discussed from the aspects of velocity streamline structure, turbulent kinetic energy distribution, and pressure distribution. The results show that the shape, arrangement position, height and gap ratio of the vortex generator have a great influence on the aerodynamic drag of the heavy-duty truck. The fork-shaped vortex generator has the smallest aerodynamic drag coefficient when it is located at the rear end of the cargo compartment, and its value is 0.699 6. Compared with the original model of the truck, the drag reduction rate is 11.7%, indicating that the fork-shaped vortex generator is the best vortex generator shape. The installation of the vortex generator can reduce the area and strength of the vortex zone of the rear of the truck, and delay the separation of the tail airflow, thereby reducing the differential pressure resistance of the front and rear parts of the truck.

    • Error compensation of digital-image-correlation displacement field measurement

      2020, 43(12):59-67. DOI: 10.11835/j.issn.1000-582X.2020.12.006

      Abstract (615) HTML (826) PDF 2.27 M (1044) Comment (0) Favorites

      Abstract:The error of digital image correlation (DIC) displacement field measurement is always conflicted with the iteration times of algorithm. To reduce the calculation error, the number of iterations has to be increased, which will result in a heavy computing burden. However, the error of the non-iteration method is usually high. To solve the problem, a BP neural network-based error compensation method is proposed. The non-iteration optical flow algorithm is selected as analytical example and its error is also analyzed. The displacement measurement of a simulated speckle image and its error are used as training data. The displacement measurement result is compensated by the predicted value. The compensation experiment is carried out and it shows that the error after compensation drops by 50% and the histogram of the error is also reduced.

    • Development and research of measurement and control system based on virtual traffic scene and test bench

      2020, 43(12):68-77. DOI: 10.11835/j.issn.1000-582X.2020.10.007

      Abstract (538) HTML (826) PDF 4.98 M (904) Comment (0) Favorites

      Abstract:At present, the structure of electric vehicles is diversified, and the research and development cycle is getting shorter and shorter. Traditional test benches will be unable to meet the testing needs. In combination with the development status of electric vehicles and actual test requirements, and in order to carry out vehicle-level integration testing of the performance of powertrain components in a laboratory environment, a design method combining vehicle simulation test and test bench is proposed to simulate drive virtual reality. The simulation system and the platform dynamic loading control system are integrated to maximize the simulation of the actual vehicle running condition, by which to check the coordination of key components, thus improving the bench testing efficiency and product development cycle. Finally, the EM-CVT bench test is taken as an example to verify the feasibility of the bench measurement and control system.

    • On thermo-mechanical fatigue behaviors of a nickel-base single crystal superalloy

      2020, 43(12):78-86. DOI: 10.11835/j.issn.1000-582X.2019.266

      Abstract (602) HTML (1007) PDF 5.95 M (907) Comment (0) Favorites

      Abstract:The purpose of this paper was to explore the thermal fatigue deformation and fracture mechanism of single crystal alloy and enrich the theory related to it. A nickel-base single crystal superalloy was employed to study OP thermo-mechanical fatigue behavior by using scanning electron microscope (SEM), transmission electron microscope (TEM) and some other research methods. The main results are summarized as follows:A mean tensile stress is observed in OP TMF. With the mechanical amplitude increasing from 0.6% to 0.9%, the fatigue life decreases, whereas the stress range and the plastic strain increase. The cyclic stress response curve of the alloy shows cyclic hardening at half cycle of low temperature while at the high temperature half cycle, the maximum compressive stress decreases during test, indicating a cyclic softening. The main mechanism for OP TMF is the formation of local slip bands in {111} planes. The interaction of creep, oxidation and fatigue damage lead to shorter life for TMF than isothermal fatigue. The fracture and propagation of slip bands is the main fracture style for OP TMF. The tensile stress is dominant factor affecting the fatigue life in the test.

    • Helicopter high-bandwidth flight control design using integrated rotor control

      2020, 43(12):87-98. DOI: 10.11835/j.issn.1000-582X.2020.300

      Abstract (479) HTML (1031) PDF 1.04 M (896) Comment (0) Favorites

      Abstract:This paper presents a high-bandwidth flight control design for helicopters using an integrated rotor control system. Based on an explicit model-following control design, a rotor state feedback control law was developed and integrated into the baseline control system. The rotor/body feedback gains were comprehensively optimized to improve the stability of helicopter and a rotor control augmentation was designed to enhance command tracking ability, based on which a design method of command model parameters was proposed to improve helicopter attitude response bandwidth and attitude quickness. Finally, by a high-order helicopter flight dynamics model, the helicopter handling qualities were analyzed. The results show that the integrated rotor control system can maintain the stability margin of the baseline control system while improving the control frequencies. The roll and pitch control bandwidths are improved by 10% and 18% respectively, while the roll and pitch attitude quickness are improved by 20% and 25% respectively.

    • Simulation of the effect of turbulent pulsation on bioreactor operation

      2020, 43(12):99-107. DOI: 10.11835/j.issn.1000-582X.2019.265

      Abstract (443) HTML (683) PDF 2.67 M (793) Comment (0) Favorites

      Abstract:In order to study the effect of turbulence pulsation on the operation of bioreactor, a gas-liquid two-phase flow model was constructed and verified for a vibrating grille reactor with zero time-averaged velocity. The numerical simulation of gas and water flow in the reactor was carried out with the help of Fluent software, and the relationship between turbulent fluctuation intensity and gas holdup, oxygen transfer coefficient and Reynolds stress under ten working conditions was obtained. Based on the physical and chemical data of biofilm, the effect of turbulent pulsation intensity on biofilm growth was analyzed. The results show that increasing turbulent pulsation can effectively increase the gas holdup and oxygen transfer coefficient in the reactor and promote the high efficiency mass transfer between gas and liquid phases. For the vibrating grille bioreactor used in this study, when the turbulence intensity q<2.7 cm/s, the biofilm thickness and density increase with the increase of turbulence intensity, when q>2.7 cm/s, the Reynolds stress plays a significant role, the biofilm becoming thinner and denser gradually. The biofilm growth and pollutant removal effect is the best when the turbulence intensity q=3.4~4.8 cm/s. This study can provide a reference for the design and operation optimization of the bioreactor.

    • Research progress in preparation and doping modification of α-Fe2O3

      2020, 43(12):108-117. DOI: 10.11835/j.issn.1000-582X.2020.299

      Abstract (780) HTML (5148) PDF 1.24 M (1563) Comment (0) Favorites

      Abstract:Nano-iron oxide (α-Fe2O3) is characterized by its stable chemical properties, environmental friendliness, low preparation cost, and narrow band gap, which makes it an ideal visible-light catalyst. The article introduces the research progress of different preparation methods of α-Fe2O3, with an emphasis on the preparation process of some special structures. The research focuses on the effects of different dopants on photocatalytic performance for degradation of organic pollutants and on their enhancement mechanism as well. Also, the development trends and application prospection of doped α-Fe2O3 are summarized.

    • Effects of pH on hydrothermal synthesis of red phosphorus crystals and their photocatalytic activity

      2020, 43(12):118-124. DOI: 10.11835/j.issn.1000-582X.2020.12.012

      Abstract (516) HTML (1621) PDF 2.57 M (1254) Comment (0) Favorites

      Abstract:With commercial red phosphorus (C-RP) as the raw material and NaOH as the regulator, the HRP-pHx (x=5, 7, 9) photocatalyst was obtained by hydrothermal treatment. The photocatalytic activity of HRP-pHx was evaluated by photodegrading Rhodamine B (RhB), in which HRP-pH7 manifested the highest photocatalytic activity. Its rate constant for RhB was 3.1×10-2, which was 2.8 times that of HRP. The series characterization results showed that the main reason for the RP photocatalytic activity enhanced by adjusting pH is that the uniform structure and the smaller particle size make HRP-pH7 have more active sites than HRP. The repeated experiments indicated that HRP-pH7 was a stable photocatalyst for degrading RhB (the degradation rate was over 92% for reusing the catalyst the fourth time). In active species trapping experiments it was found that the photogenerated holes and superoxide free radicals played a main role in degrading RhB.

2020-12-31
Volume 43, No. 12

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