In order to improve the torque to volume ratio of magnetorheological （MR） brakes, a MR brake with internal and external fluid flow channels was developed.

Firstly, the structure and working principle of the MR brake with internal and external fluid flow channels were introduced, and the mathematical model of the braking torque was established based on Bingham constitutive model. Secondly, in order to obtain the optimal structure size of the MR brake, structural optimization design was carried out based on the non-dominated sorting genetic algorithm (NSGA-Ⅱ). Finally, the prototype of MR brake was fabricated, the torque performance test system was built, and the braking performance test was conducted for the MR brake.

There are both internal and external fluid flow channels in the MR brake. Six effective damping gaps are obtained by reasonable setting of magnetic conductive and magnetic isolating materials in the MR brake, so that it can produce excellent torque performance under the premise of the same size. The theoretical calculation results show that the braking torque and the adjustable range after optimization are increased by 30.23% and 16.58% respectively compared with those before optimization. Test results show that at the applied current of 2.0 A, the maximum braking torque is 44.28 N·m, and the dynamic adjustable range is 17.8. The relative errors of the braking torque and the dynamic adjustable range between the test values and the theoretical calculation values are 6.5% and 16.1% respectively, which verifies the rationality of the design.

To solve the problem of no direct mechanical or hydraulic connection between the brake actuator and the brake pedal in an electronic mechanical braking system, leading to no feedback of road feel, a brake pedal feeling simulator was proposed based on magnetorheological dampers.

Ansys/Maxwell and Matlab/Simulink were used as the platform. The structural design of the sinking brake pedal feeling simulator, the structural design of magnetorheological damper, magnetic circuit analysis and electromagnetic simulation were carried out respectively, and the simulation analysis of traditional proportional-integral-derivative (PID) and fuzzy adaptive PID control under different working conditions of the whole system was compared.

The simulation results show that the brake pedal feeling simulator can track the characteristic curve of the traditional pedal well under different working conditions and has wide applicability. Compared with the traditional PID control effect, the fuzzy adaptive PID control has higher control precision and smaller control error, and has good application prospects.

A novel two-stage compound amplification mechanism design scheme was proposed to address the friction and clearance issues inherent in traditional revolute pairs within the large stroke design of micro-displacement platforms. The aim was to achieve high-precision and significant stroke displacement amplification through structural innovation.

Utilizing the theory of material mechanics, a static model was established. A two-stage compound amplification structure that integrated a flexible hinge lever amplification mechanism with a bridge amplification mechanism was employed. Piezoelectric ceramics served as the driving source, and a parameter optimization model was developed using Matlab software. The impact of key structural parameters on both the amplification ratio and input stiffness was systematically analyzed to identify the optimal parameter combination. The optimized structure underwent validation through multi-physical field simulation via finite element analysis.

Following optimization, the mechanism attains an impressive displacement amplification ratio of 13.1 times, with its natural frequency reaching 92.2 Hz. The maximum discrepancies between theoretical calculations and simulation results of the amplification ratio and natural frequency are recorded at 2.4% and 3.5%, respectively, thereby demonstrating the feasibility of this structural design.

To address the problem that pure rolling bevel gears are prone to angular velocity mutation, vibration, and noise excitation under the influence of mounting errors, a tooth surface design method with low sensitivity to mounting errors was proposed.

Firstly, based on the influence of installation errors on angular velocity, the transmission error curve was preset as a parabolic type. Secondly, the theoretical tooth surface of the pinion was modified using the preset transmission error curve to establish a mathematical model of the target tooth surface. Finally, a 3D solid model of the modified bevel gear was constructed, and tooth contact analysis was performed.

The results show that the derived transmission error curve is consistent with the preset curve, validating the effectiveness of the modification. The actual meshing points of the optimized tooth surface deviate from the edges, and the overall contact area centers on the tooth surface, effectively avoiding edge contact and stress concentration.

The pipe belt conveyors are crucial equipment for bulk material transportation with significant environmental advantages. This study is aimed to quantify the lateral bending stiffness of steel cord conveyor belts.

Based on the analysis of standard ISO 703:2017, the measurement and analysis method for the lateral bending stiffness was determined. Numerical model and 3D simulation model of the steel cord conveyor belt were established. Deformation data under different schemes was obtained using numerical analysis method and finite element method. Error analysis was conducted to demonstrate the validity of the models. Furthermore, a generalized deflection formula for the lateral bending stiffness was derived based on the functional dependence of the belt's troughability on elastic modulus, linear mass, and cross-sectional geometric parameters.

The results provide a new perspective for quantifying the lateral bending stiffness of pipe conveyor belts and offer a basis for their design and engineering practice.

To accurately and efficiently analyze the magnetic and dynamic characteristics of multishaft double ring-plate magnetic gears (MDRMGs), improve the working conditions of CPMG arm bearings, and extend their service life, a multishaft double-ring magnetic gear transmission structure was designed by combining magnetic gears with mechanical ring-plate gears.

A magnetic field unit classification method was proposed, and then a mathematical model for air-gap magnetic field and static torque was established, which was efficient and took the end leakage magnetic effect into account. Meanwhile, based on the Riccati transfer matrix method, a dynamic model of the eccentric shaft rotor system of MDRMG was constructed.

A comparison between the magnetic field unit classification method and the finite element method shows that the results of magnetic flux density and magnetic force obtained by the two methods are highly consistent, but the calculation time of the magnetic field unit classification method is shorter. The analysis also reveals that changes in the ring-plate spacing affect the classification calculation of magnetic field units and the lumped parameters in the dynamic model, the static magnetic torque of MDRMG increases with the increase of ring-plate spacing, while the critical speed of the eccentric shaft decreases as the ring-plate spacing increases. The magnetic field unit classification method can efficiently and accurately analyze the air-gap magnetic field and torque characteristics of MDRMG. In addition, the ring-plate spacing has a certain impact on the magnetic field and dynamic performance of MDRMGs.

Contact fatigue failure is the primary failure mode for gears operating under extreme conditions such as high speed, heavy duty, and high temperature. It has become a significant technical bottleneck limiting the development of aviation equipment toward higher reliability, longer life, and higher power density. Predicting contact fatigue life is now a critical focus of both engineering and academic research. The quantitative prediction research of gear contact fatigue life was carried out.

Firstly, over 400 rolling contact fatigue specimens made from 9310 aviation gear steel were prepared and subjected to more than 5 000 hours of fatigue testing. The investigation examined the effects of service conditions, such as contact stress and slip rate, as well as surface integrity states created by over ten processes including carburizing grinding, shot peening, fine particle peening, and rolling finishing, on rolling contact fatigue life. Secondly, the Lundberg-Palmgren （LP） theory was modified using multiple linear regression methods, resulting in an LP rolling contact fatigue life prediction formula based on service conditions and surface integrity parameters.

It is found that increasing the slip rate from 10% to 30% reduces the fatigue life at a contact stress of 3 000 MPa by 52.6%, from 2.28×10⁶ r to 1.08×10⁶ r. Additionally, when the contact stress is 3 000 MPa and the slip rate is 20%, dual shot peening significantly improves fatigue life, increasing it by 113.8% from 1.52×10⁶ r in the carburizing grinding state to 3.25×10⁶ r. The derived LP contact fatigue life prediction formula, considering service conditions and surface integrity, demonstrates an error margin within twice dispersion band, thus meeting engineering application requirements.

To solve the problem of no direct mechanical or hydraulic connection between the brake actuator and the brake pedal in an electronic mechanical braking system, leading to no feedback of road feel, a brake pedal feeling simulator was proposed based on magnetorheological dampers.

Ansys/Maxwell and Matlab/Simulink were used as the platform. The structural design of the sinking brake pedal feeling simulator, the structural design of magnetorheological damper, magnetic circuit analysis and electromagnetic simulation were carried out respectively, and the simulation analysis of traditional proportional-integral-derivative (PID) and fuzzy adaptive PID control under different working conditions of the whole system was compared.

The simulation results show that the brake pedal feeling simulator can track the characteristic curve of the traditional pedal well under different working conditions and has wide applicability. Compared with the traditional PID control effect, the fuzzy adaptive PID control has higher control precision and smaller control error, and has good application prospects.

For slotted disk magnetic couplers, the slotted conductor disk complicates the magnetic circuit during operation, increasing the difficulty of calculating electromagnetic torque. A reliable electromagnetic torque prediction model was established, and its torque characteristics were studied.

A 18-pole 16-slot disk magnetic coupler was studied. Firstly, via the equivalent magnetic circuit method, induced eddy currents from adjacent and self-magnetic circuits were introduced as a branch into a new model. Considering 3D end effects and combining Ampere's and Kirchhoff's laws, air gap flux and output torque expressions were derived. Secondly, the coupler was simulated and analyzed by the finite element simulation software, obtaining distributions of air gap magnetic field and eddy currents, and torque variations with air gap thickness and speed difference under adjacent eddy current influence. Finally, a test platform was established to verify theoretical and simulation results.

The results show that the results of theoretical calculation, finite element simulation and test are basically consistent. The proposed theoretical model has high accuracy, providing a reliable prediction model for studying the torque performance of such couplers.

Alternating magnetic fields induce vibrations in mechanical components, thereby generating noise. Fluctuations in electromagnetic excitation forces and electromagnetic torque are the primary causes of electromagnetic vibration noise. To analyze the generation mechanisms and functional patterns of these fluctuations, an electromagnetic vibration noise analysis was conducted on a slotted disk-type asynchronous magnetic coupler with 9 pole pairs and 16 slots.

Firstly, theoretical formulas for air-gap magnetic flux density and electromagnetic excitation force were derived using the magnetic scalar potential permeance method and Maxwell stress tensor method. Combined with finite element simulation, the harmonic order amplitudes of the Fourier decomposition of air-gap magnetic flux density and electromagnetic excitation force were obtained. Secondly, based on the energy method, an expression for cogging torque was derived. Finite element simulation was employed to determine the cogging torque and electromagnetic torque fluctuations generated during the operation of the magnetic coupler. Thirdly, an electromagnetics-structural-acoustic multi-physics coupling model was established. Using the modal superposition method, vibration acceleration and displacement produced during stable operation of the magnetic coupler were obtained, and the characteristics of its electromagnetic noise were analyzed. Finally, a test platform for the magnetic coupler was constructed to measure electromagnetic noise during stable operation. Test results were compared with simulation outcomes to validate the theoretical analysis.

The results indicate that low-order electromagnetic excitation forces are the main causes of vibrations in the magnetic coupler, and significant vibrations occur when the frequency of the electromagnetic excitation force approaches the natural frequency of the magnetic coupler. Comparison with simulation results shows that the test data obtained from the magnetic coupler test platform confirm the accuracy of the theoretical analysis.