When T22 ferritic steel and 800H austenitic alloy were welded, premature failures often appear on the heat-affected zone side of ferritic steel, due to carbon migration. The carbon chemical potential gradient is the driving force of carbon diffusion. Usually, adding a transition layer between dissimilar alloys is an effective way to reduce the chemical potential gradient. Therefore, in this study, thermodynamic and kinetic modeling tools were used for designing transition layers between T22 and 800H to mitigate carbon migration. Firstly, simulation results show that a linear transition zone can decrease the migration of carbon to reduce the decomposition of carbide on the T22 side. In addition, two layers transition was designed to further depress carbon migration. Compared with the wider linear transition zone, it can gain a similar favorable effect. Moreover, the width of the transition zone can be significantly minimized. The designed constant composition is propitious to drop the experiment complexity.
When the involute spur gear is working, a large bending stress is generated at the root of the tooth, which is prone to root fracture. In this paper, the double arc transition curve, the arc transition curve and the elliptical arc transition curve are compared. Through the dynamic finite element simulation of Abaqus software, it is concluded that the stress on the elliptical arc transition curve is the smallest. The stress at the root of the tooth can be reduced, the possibility of gear fatigue fracture can be decreased, which providing a certain reference for the design of plastics gears.
The torque pulsation generated by brushless DC motors during motion can lead to reduced system stability and reliability, as well as mechanical vibration, resonance and noise problems. And they require the installation of position sensors to provide commutation signals, which in turn increases the complexity and cost of the motor structure. To address these problems, a research strategy combining traditional dual closed-loop control with the extended Kalman filtering algorithm is proposed based on the study of traditional motor control. On the basis of the traditional double closed-loop control system, a feedback signal processed by extended Kalman filter algorithm is added.The simulation results show that this strategy can get accurate estimation of speed and rotor position, and the system with the extended Kalman filtering algorithm is more stable and better controlled when the motor speed is given and changed.
In today's increasingly stringent emission requirements, the requirements for aftertreatment are also increasing. Controlling the motor in the post-processing system plays a key role. In this paper, the method of controlling the motor will be analyzed. When analyzing the traditional PID controller, it is found insufficient, so a new single neuron PID controller is used, which can better control the DC brushless motor than the former; the latter structure has better adaptability. The advantages and disadvantages of the two controllers are compared in the Simulink simulation of MATLAB, and it is concluded that the latter has a faster response speed and stronger adaptability.
Brushless DC motor (BLDCM) is characterised by time-varying, non-linear, strong coupling and many variables, and have been extensively studied in the area of motor control. The traditional PID control method as a regulator is not ideal to achieve the desired speed system control effect. Therefore a fuzzy PID controller is designed to implement. The working principle and mathematical model of brushless DC motor (BLDCM) is briefly analyzed, and a simulation model of the brushless DC motor control system is built in the Simulink module of MATLAB software. Speed closed-loop speed regulation is realized by fuzzy PID control, while the fuzzy PID control is used to achieve the speed closed-loop speed regulation, and a double closed-loop speed control system model of the BLDCM is built. Finally, through the analysis of the simulation results, the fuzzy PID control BLDCM drive system has faster dynamic response and stronger anti-interference ability compared with the traditional PID control.
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