To address the issues of crawling and poor motion stability in low-speed and heavy-duty conveyor chain transmissions, a dynamic model of the above conveyor chain transmissions was established based on multi-body dynamic theory, and the research on dynamic characteristics was carried out, aiming to provide guidance for enhancing the stability of such conveyor chain transmission systems.

By considering the structural characteristics of low-speed and heavy-duty conveyor chain transmission systems and the effects of conveying loads, the mechanical properties of the conveyor chain nodes were simulated using Hooke’s law, and a dynamic model with 107 degrees of freedom of the conveyor chain was constructed. The modal superposition method was adopted to solve the dynamic model, the dynamic characteristics of the low-speed and heavy-load conveyor chain were obtained, and the influence laws of the slack side sag and the tight side friction force of the conveyor chain on the transmission speed variation were studied.

The results show that reducing the slack side sag and decreasing the friction coefficient between the conveyor and the guide rail can effectively reduce the occurrence of the crawling phenomenon in conveyor chain transmission and improve the motion stability of the conveyor chain transmission systems.

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.

Existing research on flexible hinges corresponds to complex expressions for flexibility and rotational accuracy calculations. To address this issue, a new type of catenary flexure hinge was designed, and a method for establishing the hinge’s compliance and rotational accuracy model by approximating arc segments with straight-line segments was proposed.

Firstly, by defining the flexure hinge as a series combination of tapered and expanded sections, the curve in the tapered segment was divided into several arc segments, and the curve segments were approximated with straight segments. Based on the Castigliano’s second theorem, a method by calculating the flexibility of the tapered section and then establishing the hinge flexibility and rotational accuracy model through matrix operations was established. Secondly, using specific examples, the derived formula, literature formulas, and the finite element method were employed for calculations. When the curve segment was finely divided, the calculation results align well, thereby verifying the formula’s correctness. Thirdly, the influence of structural parameters on the flexibility, rotation accuracy, and flexibility-accuracy ratio of catenary flexure hinges was analyzed. Finally, the bending flexibility and flexibility-accuracy ratio of the catenary, conic, and their hybrid hinges were analyzed with the same structural parameters.

The results show that a single parameter has a negative correlation with flexibility and rotation accuracy of the catenary hinge, and reducing the minimum thickness is the best way to improve flexibility. Under the same structural parameters, the flexibility and flexibility-accuracy ratio of the catenary hinge is between parabolic and circular shapes. Choosing a hybrid hinge with a section of high flexibility for the tapered section and a section of low flexibility for the expanded section allows for a balance between flexibility and motion accuracy.The greater the difference in flexibility, the better the flexibility-accuracy ratio.

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 wave generator, as the driving component, has its profile curve directly affecting the deformation and stress distribution of the flexible wheel. To reduce the stress on the flexible wheel and improve its fatigue performance, a design method for a three-term cosine cam wave generator was proposed.

The profile curve of the three-term cosine wave generator was composed of a constant term, represented by the base circle radius, and three cosine terms superimposed. By using the curvature variation coefficient at the major axis, the correction factor at the minor axis, and the clearance of the flexible bearing as variable parameters, the influence of these parameters on the performance of the wave generator was analyzed, and the optimization of a specific harmonic reducer model was validated. Finite element analysis was performed on the flexible wheel structure after incorporating the new cam structure under expansion, no-load, and loading conditions, and comparisons were made with the pre-optimized structure to analyze the stress distribution on the flexible wheel.

The finite element results indicate that, compared to the traditional cosine wave generator, the flexible wheel under the three-term cosine wave generator exhibits superior stress performance under various working conditions and achieves longer fatigue life.

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.

The industrial robot industry has put forward higher requirements for RV reducers, and the precision life reflects the ability of the reducer to maintain transmission accuracy, which is one of the most important design criteria and usage indicators. To improve the precision performance of precision reducers, it is crucial to evaluate their reliability. Therefore, the degradation characteristics of precision reducers were analyzed.

Taking the RV80E reducer as an example, a random degradation model based on Gamma process was proposed. Combined with the performance degradation data of the reducer transmission accuracy, the model parameters were estimated based on the matrix method and the maximum likelihood estimation method. A Gaussian process regression model optimized by genetic algorithm was established using vibration characteristic data to optimize the prediction of transmission accuracy.

The results show that the prediction accuracy based on Gaussian process regression model is significantly better than that of the traditional regression model. The posterior distribution parameters of the random degradation model are updated by using the algorithm to predict the results, which can effectively evaluate the reliability of the accuracy life of RV reducer and lay the foundation for further reliability optimization design of accuracy life.

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 address the longitudinal vibration of long-distance belt conveyors during starting, the dynamic equations of the belt conveyor were established based on the analysis of the viscoelastic properties of the conveyor belt. Taking a practical long-distance belt conveyor as an example, a dynamic simulation model was constructed using AMESim software to study the starting acceleration curve and loading time.

The effects of common starting curves on the dynamic tension of the conveyor belt were analyzed, and a new combined starting curve (sine+parabolic) was proposed. The curve was optimized by introducing a creep phase and adjusting the pre-starting speed. The tension variations under different loading times were then analyzed.

The results show that the optimized sine and parabolic starting curve reduces the maximum tension of the conveyor belt by 5.8% compared with the commonly used sine acceleration curve. Furthermore, loading materials after stable operation effectively reduces the tension impact and extends the service life of the conveyor belt.

In order to increase the depth of planting seedlings and reduce the width of transplanting holes, so as to improve the uprightness of rice pot seedlings after transplanting, the comprehensive design and test research of the transplanting mechanism based on the belt-shaped transplanting trajectory were carried out.

Firstly, a belt-shaped transplanting trajectory that can reduce the width of the hole was proposed, and the posture analysis of 10 key posture points on the transplanting trajectory was conducted according to the parameters of the transplanting mechanism and the requirements of motion design. Secondly, the seven-tooth non-circular gear planetary gear train transplanting mechanism was simplified into a planar 2R open chain mechanism, and a mechanism mathematical model based on the belt-shaped transplanting trajectory was constructed using the multi-position motion synthesis theory. Then, the objective function of the minimum change of the length of the planet carrier was established, and the App Design module of Matlab software was used to develop the multi-position motion comprehensive solution software for the rice pot seedling transplanting mechanism based on the genetic algorithm, and the optimal solution set of the key parameters of the transplanting mechanism was obtained. Finally, a simulation on the kinematic characteristics of the transplanting mechanism was carried out using Adams software, and a test prototype was fabricated to conduct the test research on field transplanting.

The simulation results show that the transplanting mechanism has the characteristic of quick return, and all the parameters and kinematic characteristics of the mechanism meet the design requirements, where the planting depth and transplanting hole width are 22.19 mm and 9.78 mm, respectively, which represent increases of 41.9% and decreases of 27.9% respectively compared to the corresponding value in relevant literature. The results of field test show that the average planting depth of rice pot seedlings is 22.84 mm, the average hole width is 10.37 mm, the excellent rate of verticality is 93.3%, and the transplanting effect is satisfactory.