The applications, evaluations, and funding of several types of projects that were classified into the talent and exploratory funding categories at mechanical design and manufacturing discipline (division Ⅱ of engineering science) of the National Natural Science Foundation of China in 2023, as well as the research progresses and findings of the executing and finished projects were reviewed. Specific measures of mechanical design and manufacturing discipline were illustrated, such as the reform of scientific fund, talent cultivation, and future research. Finally, a short prospect of the work in 2024 was introduced．

 An efficient multi-grid equation solving method was proposed based on the h-refinement of splines to address the challenges posed by large-scale ITO computation and low efficiency of traditional solving methods. By the proposed method, the weight information obtained through h-refinement interpolation between coarse and fine grids was used to construct the interpolation matrix of the multi-grid method, thereby enhancing the accuracy of mapping information for both coarse and fine grids and improving computational efficiency. Additionally, a comprehensive analysis of the multi-grid solving process was conducted, culminating in the development of an efficient GPU parallel algorithm. Numerical examples illustrate that the proposed method outperforms existing methods, demonstrating speedup ratios of 1.47, 11.12, and 17.02 in comparison to the linear interpolation multi-grid conjugate gradient method algebraic multi-grid conjugate gradient method, and pre-processing conjugate gradient method respectively. Furthermore, the acceleration rate of GPU parallel solution surpasses that of CPU serial solution by 33.86 times, which significantly enhances the efficiency of solving large-scale linear equations.

Aiming at the hysteresis nonlinearity of the piezoelectric driven systems for tunable external cavity diode lasers, a modelling and control method was proposed herein based on Rayleigh-BP model. Firstly, a Rayleigh-BP rate-dependent hysteresis model was developed by spatial expansion method, which achieved an accurate prediction of rate-dependent hysteresis nonlinearity of piezoelectric driven systems. Secondly, the inverse model of Rayleigh model was solved by an inverse algorithm, and the model was combined with a BP neural network to design a feedforward controller to compensate the systems. Finally, the feedforward control method was validated by simulation and experiments. The results show that the Rayleigh-BP model developed has high accuracy, the root mean square error is only as 0.0469 μm at 10 Hz. The feedforward control method may significantly improve the linearity of the system outputs, the root mean square error of the simulation results is as 0.0274 μm and the linear correlation coefficient R2 is as 0.999 92 at 40 Hz. The experimental results show a root mean square error of 0.0506 μm and a linear correlation coefficient R2 of 0.999 55 at 30 Hz, which greatly reduces the hysteresis phenomenon.

In order to study the control effectiveness of different heat treatment processes on the residual stress of laser cladding, a thermo-mechanics coupling model was established by using ANSYS finite element analysis software. The temperature and stress fields during the laser cladding of 316L stainless steel were simulated under the conditions of preheating(22~900 ℃) before cladding, annealing treatment(200~1000 ℃) after cladding and combined heat treatment before and after cladding. The results show that preheating has the greatest influence on the temperature of molten pool. The temperature of the molten pool increases with the increase of the preheating temperature. Annealing treatment has the best effect on improving the residual stress of laser cladding, and the residual stress is reduced by about 50% at 800 ℃. Comparatively, followed by preheating and annealing treatment, the residual stress is reduced by about 35%. In addition, preheating treatment may also effectively adjust the residual stress, with a reduction of 20% at 500 ℃. 

To study the compressive mechanics properties of pillar centered cubic lattice with different reinforcement directions and their filling structures, silicone rubber filled lattice structure test specimens were prepared herein. The compressive mechanics properties of two lattice structures(BCC1 or BCC2, loading direction was either the same or perpendicular to the direction of pillar rod in body centered cubic lattice with pillars) filled with silicone rubber were studied through experimental and simulation methods. The equivalent elastic modulus and compressive platform stress of two lattice structures were conducted using Timoshenko beam theory and ultimate load method. The results indicate that the proposed theoretical model may effectively predict the equivalent elastic modulus and compressive platform stress of two type lattice structures. After filling, the compression strength and energy absorption performance of the two lattice structures are enhanced, while the enhancement effect of the BCC2 structure is more significant. For the BCC1 lattice, rubber filling enhances the bearing capacity of the internal members. However, for the BCC2 lattice structure, rubber filling reduces the bending deformation of the members near the V-shaped shear band. As the radius of the lattice structure increases, the energy absorption coupling factors of both lattice structures first increase and then decrease, yet the energy absorption coupling factor of BCC1 type structure changes more significantly.

The distribution of machining residual stress of nickel-based superalloys had a significant influence on the product quality. To achieve the control method of residual stress, the effects of processing parameters, tool parameters and mechanics-thermal coupling on the residual stress distribution of nickel-based superalloys were studied by means of simulation and experiments. It is found that the change of cutting depth will affect the radial and tangential residual stresses at the same time, and the change of feed rate per tooth mainly affects the residual stress in the feed direction. When the rotating speed increases, the temperature field becomes stronger, the materials are softened, the milling forces are decreased, and the thermal stress is gradually increased. The optimal proportioning scheme is obtained by the method of parameter combination proportioning. Taking the machining of engine blade parts as an example, the method based on parameter optimization may effectively control the residual stress of Nickel-based superalloys.

 An optimization method of integrated casting structures was constructed systematically, and based on the super-element model of body system, body casting part lightweight improving with multi-performance constraints was realized. Firstly, complex body systems were reduced, the sub-system division principle and method were proposed for continuous body structure. Super-element reduction of the sub-system was conducted to ensure analysis accuracy and improve calculation efficiency, laying the foundation for rapid optimization. Secondly, performances of casting structures and body systems were considered simultaneously, the compromise programming methods were used to normalize static and dynamic sub-targets and construct the comprehensive objective function, weight coefficients of sub-targets were obtained by analytic hierarchy process(AHP), and then multi-model topology optimization was carried out to determine position distribution of reinforcements. Furthermore, designability and manufacturability were considered simultaneously, parametric definition of variable thickness drawing surface of casting structure was carried out, manufacturing constraints were applied during optimization processes, and then thickness parameter design was completed based on combined surrogate model. The results show that, under the premise of ensuring the analysis accuracy, reduced body system models improve computing efficiency greatly, and save 97.3% of computing resources. Casting triangular beam lightweight may be achieved while improving related performance by conducting structure optimization, which indicates correctness and practicability of the proposed method. 

 In view of the ubiquitous problems in tunable diode lasers, such as small tuning range of output optical frequency without mode hopping, low scanning frequency and complex structure, the dynamic characteristics of the internal piezo-based actuated systems of tunable diode lasers were studied. Based on the design goals of improving rotation accuracy and reducing axis offset, a multi-leaf parallel star-shaped flexible mechanism structure was proposed. After that, based on the Lagrange equation and Duhamel integral, the differential equation of motion and the vibration equation of the piezo-based actuated systems were respectively established.Then, the dynamics model of the flexible mechanisms was established and the structural parameters were optimized. Finally, a test platform was built to explore the mechanical response characteristics of the piezo-based actuated systems and the tunable range of tunable diode lasers. The experimental results show that the first-order natural frequency of piezo-based actuated systems is as 2187 Hz. The maximum axis offset of the flexible mechanisms is as 0.947 mm. In the mode-hop-free tuning performance tests of tunable diode lasers, a mode-hop-free tuning range of 103.5 GHz is achieved at a tuning frequency of 20 Hz. 

Double deck EMUs were equipped with amplifiers for secondary lateral damping to mitigate the vibrations caused by primary hunting behaviour. However, increased secondary lateral damping could negatively impact the lateral ride quality of the vehicles. In order to solve the problem of poor lateral ride quality in high-speed double deck EMUs, a mathematical model of the inter-car rolling damping devices was created by taking into account the working principle of the damper as well as the rolling and yaw state of the carbody, and the simulation models of the damper established in AMEsim software were verified with the bench tests. Finally, the key parameters of the inter-car rolling damping devices were optimized by establishing a co-simulation model between the inter-car rolling damping device and the vehicle model, without changing the existing suspension parameters of the vehicles. The simulation results show that the device may effectively improve the lateral ride quality of the double deck EMUs without affecting the vertical ride quality of the vehicles and ensure the safety of curve operations.

A new type of space mechanisms with single-closed-loop was proposed according to thick-panel origami teory, and the mobility was analyzed by using screw theory. The degree of freedom of mechanism was reduced to 1 by the introduction of Myard constraint and Sarrus constraint, and the corresponding deployable units were obtained with the names of Myard deployable honeycomb unit and Sarrus deployable honeycomb unit. M-type honeycomb mechanism and S-type honeycomb mechanism were proposed based on kinematic analysis and planar mosaic array of deployable honeycomb units. The influence regularity of various factors on folding ratio was analyzed, and the deployable honeycomb units  were optimized with the rising of folding ratio index. The results show that M-type honeycomb mechanism may achieve flat surface, and S-type honeycomb mechanism may achieve higher folding ratio index.

Rivet coating was a key factor influencing the formation and mechanics performances of riveted joints. The SSFR processes were used to join 6005A-T6 and 6A01-T5 aluminum alloy sheets herein. Three types of rivets including non-coated, Zn coated, and ZnNi coated were utilized to study the evolution laws of riveting force, energy input, and formation of the SSFR joints. Moreover, the remaining thickness of the coating layers at different positions in the joints and the diffusion of coating elements at the rivet/sheet interfaces was analyzed, and the influences of the rivet coating on the tensile-shear and cross-tension performances of the joints were investigated. The results indicate that the coating reduces the energy input generated by rivet rotation, thereby reducing the heat-affected zones of aluminum alloy materials. However, the decrease in energy input is not conducive to the formation of solid phase bonding between aluminum alloy materials in the rivet cavity, resulting in a decrease in the tensile-shear and cross-tension performances of the joints. Compared with Zn coating, the ZnNi coating has stronger wear resistance, and the remaining thickness still exceeds 40% after the stirring friction caused by high-speed rotation of rivets, which helps to improve the corrosion resistance of joints.

In the dynamic modeling of planetary gear trains, the influences of nonlinear oil film forces or linear stiffness damping forms on system dynamics characteristics were often considered. The former had high simulation accuracy but high computational costs, and the latter had high computational efficiency but ignores the time-varying effects of oil film forces and journal sleeve eccentricity, resulting in limited simulation accuracy. Therefore, a 2MW wind turbine gearbox was taken as the research object herein. A time-varying linear stiffness damping model of the journal bearing was established, and a calculation method for the additional eccentricity correction force of the journal bearing considering the time-varying eccentricity of the journal sleeve was proposed. Then, the time-varying linear stiffness damping model was coupled with the additional eccentricity correction force by using the coordination relationship between the carrier-pin and planet. Finally, a dynamic model of the planetary gear trains in wind turbine gearboxes using journal bearings was established, and the effects of operating conditions and bearing parameters on the calculation accuracy and dynamic system responses were compared and verified through experiments. The results indicate that the fluctuation of dynamic meshing force in gear pairs may cause periodic changes in the stiffness damping coefficient and additional eccentricity correction force of journal bearings. The proposed model may effectively predict system responses, especially planetary gear vibration responses, under stable and transient operating conditions. Reducing the width-diameter ratio and gap, increasing input torque may improve the system's load sharing performance.

Aiming at the problems of the accuracy in identifying geometric errors of rotation axis of five-axis CNC machines with double rotary tables, an identification model of PIGEs of rotation axis on absolute coordinate system was proposed. The actual initial coordinates of the tool ball and the workpiece ball in the machine coordinate system were established, and the actual initial position of the workpiece ball in the measured axis was obtained by the inverse matrix. The mathematical model of the double ball bar length changing included installation errors and the PIGEs of the rotation axis was established based on the four measurement patterns. The effects of PIGEs on the measurement pattern were analyzed by simulation. The results show that the parallelism error may not affect double ball bar length changing when the tool ball is at the intersection of the two rotation axis. Finally, 8 PIGEs of the rotary axis were identified through experiments, and 4 positional deviations of the rotary axis PIGEs were compensated. The experimental results show that the maximum absolute value of the compensated positional error is reduced from 203.5 μm to 5.1 μm, and the proposed identification model may effectively improve the accuracy of five-axis CNC machines. 

Turbine nozzles were crucial components in aircraft engines, and the throat area was a key parameter that directly affected the engines power performance. In response to the issues of low efficiency and inaccurate estimation in existing measurement methods for the throat area, a new method for three-dimensional measurement point processing and accurate calculation of the throat area for aircraft turbine nozzles was proposed. Comparative experiments between the proposed method and the CMM method were conducted on a multi-blade turbine nozzle sample. The experimental results show that the throat areas obtained by the proposed method are more accurate, and the results of multiple measurements and calculations have high consistency.

The pace of large wind turbine units was accelerating, and the reliability of core components was increasingly important for wind turbine operations. Sliding bearings had the advantages of high load capacity, long life, easy maintenance, scalability and small size, and they had advantages and great potential for the reliable replacement of wind turbine main bearings key components produced at home. The problems of main shaft rolling bearings in high-power wind turbines and the advantages of using sliding bearings on the main shaft were analyzed herein. The technical methods and application status of wind turbine main shaft sliding bearing design, materials, lubrication, and experimental verification were present in detail, and the existing problems of high-power wind turbine main shaft sliding bearings and future development trends were summarized. It is expected to provide reference for the digital design and industrial development of high-power wind turbine main bearings.

By adding Ni interlayers to steel plates, the reliable connections between 6061T6 aluminum alloy plates and 08Al steel plates were successfully realized, and the mechanical properties of aluminum/steel spot welding joints were significantly improved. The results show that the thickness and distribution of Ni intermediate layers on steel plates may be controlled by using the prefabricated Ni intermediate layer processes, and the formation of Al-Fe brittle intermetallic compounds may be reduced. Compared with adding Ni foil intermediate layers directly, the prefabricated Ni intermediate layer processes may effectively increase the nugget diameter. The maximum tensile sheer force of aluminum/steel resistance spot welding joints with laser cladding Ni layer on steel plates is 35.5% higher than that without intermediate layers.

Aiming at the serious wear problems of gear end face friction pairs of aviation external gear pumps, a new compound texture combining Tesla valve groove type and elliptical shape was opened on the gear end faces to improve lubrication performance. Based on hydrodynamic lubrication theory and finite element simulation calculation method, a theoretical analysis model of gear textured end face friction pair lubrication was established. Pressure distribution and velocity distribution of fluid within the end face liquid films were simulated and analyzed under conditions with and without texture, and the effects of operating and structural parameters on the openness and sealing performance of gear end faces were studied. The results show that the hydrodynamic pressure generated by the texture may make the gear end face friction pairs run non-contact, which has a positive effect on reducing friction and increasing efficiency. With the comprehensive consideration of the openness and leakage control performance of gear end face friction pairs, groove depth is as 7~9 μm, height difference is as 5~6 μm, inclination angle is as 0°~10°, and shape factor is as 0.4~0.5 are the optimal structural parameters for the texture structure.

 The rotor of the AMBs and the auxiliary bearing might produce huge impacts， vibrations and friction heat during the rotor falling which was easy to make the auxiliary bearing fail. The thermal characteristics during the vertical rotor drop on auxiliary bearings were studied， and the main factors leading to the auxiliary bearing failure during the rotor falling were analyzed herein. Subsequently， a method of reducing friction was proposed to deposit solid lubricating film(GLC) on the key surfaces of auxiliary bearings by magnetron sputtering technology， and the rotor drop tests of coated and uncoated auxiliary bearings were performed. The results show that the maximum temperature of the auxiliary bearing is as 210.60 ℃ at a drop speed of 20 000 r/min， which appear in the high-speed rubbing stage between the rotor and the inner ring end face of the bearing. The temperature is higher than the tempering temperature of bearing steel of 160 ℃， which will lead to the failure of the bearing burn. The surface appearance of the channel and end face of the self-lubricating auxiliary bearings coated with GLC film is obviously better than that of the uncoated ordinary auxiliary bearing after the drop tests. The hardness decrease of the inner ring end face caused by friction and heating is lighter， the trajectory of the center of mass and axial displacement are more stable， and the temperature rise is lower. The GLC films play a key role in self-lubrication， wear resistance and friction reduction， the service life and service reliability of the auxiliary bearings are improved. It also provides an idea and method to solve the problems of auxiliary bearing failures easily in AMBs. 

After water jet guided laser machining, CFRP exhibited thermal damages on the cut groove surfaces and cross-sections, which was an important factor affecting the materials mechanics properties and reducing the service performance. To address these issues, the influences of machining parameters on the geometric and surface morphology of grooves were analyzed, and the formation mechanism of surface and cross-sectional thermal damages was investigated herein. The results indicate that high laser power, low pulse frequency, and low cutting speed may effectively increase the depth of the grooves. The interaction between the laser and the material, as well as the flushing action of the water jet, are the main reasons for the formation of thermal damages on the groove surface. In the cutting experiment of 2 mm thick CFRP, it is found that the width of the heat affected zones in the cross-sections is related to the arrangement of the fibers. The heat affected zone width is the largest for 0° carbon fibers, followed by 45° and 135° carbon fibers, which have similar widths, and the width is the smallest for 90° carbon fibers. In addition, increasing the water jet velocity is beneficial for suppressing the expansion of the thermal affected zones. When the water jet velocity is increased from 80 m/s to 120 m/s, the maximum width of the thermal affected zones decreases by 35.7%.

An axle box bearings coupled with a railway vehicle model was developed based on Hertz contact and elastohydrodynamic lubrication theory. The effects of wheel-rail excitations on the vibration and oil film stiffness characteristics of axle box bearings were investigated. MATLAB/Simulink and UM were used to establish the bearing dynamic model and the railway vehicle model, respectively. The coupling relationship between the two was realized through the interaction force. The typical fault forms of bearings and wheelsets were simulated, and the impacts of these faults on bearing vibration and lubrication characteristics were analyzed in detail. The results show that lubrication may effectively reduce bearing vibrations. The partial bearing faults may increase the oil film stiffness, and bearing faults and wheel flats have a significant impact on lubrication. In addition, wheel-rail excitations reduce the vibration ratio of the bearing outer ring while increasing the vibration of other vehicle components and little effects on the vibrations of the car body.

In order to ensure the machining accuracy of circular-arc end mill flanks, a grinding trajectory accurate calculation method for circular-arc end mill flanks was proposed based on contact area adaptive adjustment. Firstly, the mathematical model of the flank was constructed through structural feature decomposition of the circular-arc end mill. Then, by calculating the grinding contact area between the grinding wheel and the flank, the grinding wheel posture was adaptively corrected to avoid grinding interference, which realized the accuracy and consistency of flank geometric parameter control and ensured the smooth connection of the curved surfaces. Finally, based on the implement of VC++ platform algorithm module, the effectiveness of the proposed algorithm was verified by machining simulation and grinding experiments.

The frictional heating effects caused by the interaction between brush seal wire and rotor coating directly affected the sealing performance and service life of brush seals. The theory of frictional heating effects between brush seal frictional pairs was analyzed. The experimental device of frictional heating effects between brush seal frictional pairs was designed and built. Six brush seal experimental parts with different structural parameters and brush wire materials and four frictional turntables with different coating materials were designed and processed. The effects of working condition parameters, structural parameters and different frictional pair materials on the frictional heating effects of brush seals were studied experimentally. By comparing and analyzing the maximum temperature of brush seals and the wear morphology and wear amount of frictional pairs before and after wear, the matching relationship between brush wire and rotor coating material was obtained. The results show that the maximum temperature of brush seals increases rapidly and then tends to be stable with the increase of friction time, and increases with the increase of interference. When the interference increases from 0.3 mm to 0.4 mm, the average maximum temperature of brush wires rises to 39.96 ℃. The maximum temperature increases with the increase of the brush thickness and decreases with the increase of the rear baffle protection height. When the brush wire material is cobaltbased superalloy GH605, the best rotor coating material is WC; when the brush wire material is nickelbased superalloy GH4169, the best rotor coating material is ZrO2.These two matching materials may produce lower friction heat under the same working conditions, and the wear resistance is higher than that of other matching materials.

In order to further improve unmanned hybrid vehicles trajectory tracking accuracy and energy consumption economy, this paper proposed a trajectory tracking energy-saving control fusion strategy. Firstly, the vehicle kinematics model was established, and the trajectory tracking control of the vehicle was carried out by using the model predictive control strategy. Then, with velocity as the interactive variable, a three-stage dynamic programming energy-saving control strategy was proposed. In this way, the optimal economic function was optimized online to reduce the total cost of energy consumption of the vehicles. Finally, the independent pure pursuit trajectory tracking algorithm and the power following energy-saving control were selected for comparison strategies. The results show that the proposed trajectory tracking energy-saving control fusion strategy improves the trajectory tracking effectvieness and reduces the total cost of vehicle energy consumption. The trajectory tracking errors are reduced 70.47%. The total cost of energy consumption decreases 4.52% and 25.10% in pure electric drive mode and hybrid drive mode, respectively.

 High-dimensional uncertainty propagation currently faced the curse of dimensionality, which made it difficult to utilize the limited sampling resources to obtain high-precision uncertainty analysis results. To address this problem, a high-dimensional uncertainty propagation method was proposed based on supervised dimension reduction and adaptive Kriging modeling. The high-dimensional inputs were projected into the low-dimensional space using the improved sufficient dimension reduction method, and the dimensionality of the low-dimensional space was determined by using the Ladle estimator. The projection matrix was embedded into the Kriging kernel function to reduce the number of hyperparameters to be estimated and improve the modeling accuracy and efficiency. Finally, the leave-one-out cross-validation error of the projection matrix was innovatively defined and the corresponding Kriging adaptive sampling strategy was proposed, which might effectively avoid large fluctuations of model accuracy in the adaptive sampling processes. The results of numerical and engineering examples show that, compared with the existing methods, the proposed method may obtain high-precision uncertainty propagation results with fewer sample points, which may provide references for the uncertainty analysis and design of complex structures. 

In order to reduce the shear force of 850 ton cold shears, the shearing mechanism and characteristics of the cold shear were studied, the effects of shear parameters such as shear clearance, blade inclination, shear velocity, blade width and blade overlap on shear force were analyzed by orthogonal test. Variance, range and significance were used as the indexes of influencing factors, and the priority of them were given to optimize the shear parameters and reduce the shear force. The experimental verification of the cold shear before and after the optimization of shear parameters were carried out in the workshops which show that the errors between the measured and simulated values of the shear force of the cold shear before and after optimization were within 5%, which verifies the reliability of the simulation analysis. By setting the optimal shear parameters and shearing the same steel bar, the maximum shear force of the upper shear blade is reduced by 5.84 kN, about 13%. The maximum shear force of the lower shear blade is reduced by 4.77 kN, about 9.7%. Feedbacks from workshops show that the optimization greatly prolongs the period of blade broken and blunt and improves the blade life and shearing efficiency. The results are of great significance for improving the economy and production efficiency of the equipment, and may be applied to the engineering design of the same type of cold shears.

Aiming at the problems of low quality and short die life during the production commissioning, an optimization decision method for cartridge case indenting-heading process parameters driven by small sample was proposed. Firstly, the central composite experimental method was used to design experiments, and each experimental scheme was incorporated into the finite element model for numerical simulation. Taking the maximum effective stress of indenting ejector, the maximum effective stress of heading punch and inner fillet at the bottom of the cartridge case as the optimization goals, random forest algorithm was combined to construct the multi-objective optimization model of processing parameters in indenting-heading processes of cartridge cases based on the simulation results. Secondly, the improved multi-objective grey wolf algorithm was applied to optimize the multi-objective optimization model and obtain a pareto solution. The optimal process parameter combination was evaluated and determined using the comprehensive entropy weight-TOPSIS method. Finally, the numerical simulation and processing experiments were carried out with the combination of optimal process parameters. The results show that the simulation results are consistent with the processing experiments, and the inner fillets at the bottom of the cartridge cases are filled fully, and the service life of the die is improved.

Aiming at the problems of low slicing efficiency and quality of the existing pastry slicing machines, the design analysis and parameter optimization of a slicing machine was carried out based on the new rotary-linear reciprocating mechanisms. Firstly, the design of the slicing mechanisms and the calculation of the length-diameter ratio and speed of the elliptical guide rail was carried out. Secondly, the kinematics and the statics analyses were carried out, then, based on the simulation analysis of different aspect ratios and rotational speed dynamics, the cubic polynomial fitting equation of the mean and root mean square value of the cutter acceleration was constructed as the objective function. The NSGA-Ⅱ genetic algorithm was used to optimize the long and short diameter multi-objective parameters, and the rotational speed was selected. Finally, a prototype was built to complete the comparative experiments of different speeds and the performance tests of corn cake slices. The results show that the optimal long and short diameters and rotation speeds are as 190 mm, 120 mm and 20 r/min respectively. After optimization, the cutter efficiency is increased by 75%, the maximum and average errors of the cutter feeding acceleration are reduced by 26% and 49% respectively, and the maximum and arerage errors of retract acceleration are reduced by 60% and 63% respectively. The corn cake section is neat and beautiful, which verifies the feasibility of the design.

Due to the cumulative central damage behavior in cross wedge rolling, it was prone to form central porosity defects, thus it was of great significance for high-performance manufacturing of cross wedge rolling shaft parts to accurately predict the formation conditions of central damages. The hot tensile tests were conducted under different conditions to obtain the main factors that affected material damages. Subsequently, the coupled damage constitutive models considering temperature, strain rate and stress triaxiality were proposed based on continuous damage mechanics. Furthermore, experiments on cross wedge rolling with different area reduction were conducted to calibrate the material fracture threshold of the damage constitutive model and verify the prediction accuracy of the damage model. The models were used to predict the influence laws of area reduction, spreading angle, and forming angle on central damage, which provided references for parameter selection. The results show that temperature, strain rate and stress triaxiality all significantly affect material damage behavior, and the established coupled damage constitutive models may effectively predict the evolution processes of central damages in cross wedge rolling. The central damages of cross wedge rolling are inversely proportional to the forming angle, and is directly proportional to the spreading angle and area reduction. The degree of influence of each parameters, from small to large, is in order of area reduction, spreading angle, and forming angle.

The welded joints were susceptible to defects and stress concentration, rendering them vulnerable areas for fatigue crack initiation and propagation under fatigue loads. In comparison to homogeneous materials, the microstructure and stress localization in each of regions for the joints further complicated the fatigue issue in welded structures. Unlike ideal experimental conditions, the actual service environments of welded structures were intricate, it was necessity to consider the coupling characteristics between environmental factors and welded structures when predicting welded structure fatigue life. Therefore, the internal factors influencing welded structures were summarized and analyzed while reviewing existing life prediction models from perspectives encompassing complex loads and extreme service environment. Combining the latest research progresses, the recommendations were proposed to enhance fatigue life assessment methods for the welded structures.

Parameter uncertainty and unmodeled dynamics of HPPS restricted the improvement of the control accuracy. An adaptive robust control method was proposed and applied to control the HPPS based on RISE. This paper considered the influencs of HESV control performance on the high-precision control of HPPS, and a cross-comparison test was designed. The results show that the HESV position control method may avoid sinusoidal signal distortions and reduce steady-state pressure jitter, and the HPPS pressure control method may improve the response speed and dynamic tracking capability of the systems.

Aiming at the problems that high-speed train wheels showed phased characteristics in the degradation processes, a modeling and reliability analysis method of high-speed train wheel degradation was proposed based on two-stage Wiener process. On the basis of the Markov chain Monte-Carlo（MCMC） method to estimate the unknown parameters of the model, the reliability function curve and reliability life of the wheel were obtained by Monte-Carlo simulation method for the problems that the two-stage degradation processes of the wheel were complex and the reliability analysis form was difficult to solve. Finally, the effectiveness of the model was verified by taking the measured data of a locomotive and bogie wheel in a single repair cycle as an example. The results show that due to the operating environment, the change point position of the wheel degradation processes on different sides of the bogie is different. Compared with the reliability evaluation results of the degradation model without considering the phased characteristics, the proposed model is more in line with the actual field situation. According to the reliable life prediction results, affected by the operating environment, the wheel degradation processes on different sides of the bogie has different changing point positions. By continuously obtaining the wheel degradation data, the reliable life value of the wheels may be calculated and updated by using the model proposed herein, which provides theoretical guidance for the further optimization of the wheel repair cycle.

For intelligent vehicles, if the sensing device might accurately and quickly detect the concave and convex obstacles on the roads ahead of the vehicles, the important preview information might be provided for the control of the chassis system such as the suspension of the vehicles, and finally realized the improvement of the comprehensive performance of the vehicles. Therefore, based on improved YOLOv7-tiny algorithm a recognition method was proposed for typical positive and negative obstacles such as bumps(speed bumps) and pits on the road surfaces. Firstly, the SimAM module was introduced in the three feature extraction layers of the original YOLOv7-tiny algorithm to enhance the networks ability to perceive the feature map; secondly, a smoother Mish activation function was used in the Neck part to add more nonlinear expressions; again, replacing the nearest proximal upsamping operator with the up-sampling operator to enable the network to aggregate contextual information more efficiently; and lastly, the WIoU was used as the localization loss function to improve the convergence speed as well as the robustness of the network. The offline simulation experimental results show that compared with the original model, the improved model improves the average accuracy by 2.5% for almost the same number of parameters with an intersection ratio of 0.5 between the predicted and real frames. The improved model is deployed to a real vehicle, and the real-vehicle experiments verify that the model may effectively detect the obstacles appearing on the road in front of the vehicles, indicating that the proposed algorithmic model may accurately provide the pre-precedent information for obstacle detections.

The journal bearings of planetary gears in wind turbine gearboxes were often designed with the inner holes of the planetary gears and the pin shaft as the shaft sleeve and journal, respectively. However, the meshing bending moment of the helical gears might easily cause misalignment between the planetary gears and the pin shaft, resulting in high risk of edge contact and affecting the operating life. Taking the planetary gear journal bearing of a 6 MW drive chain gearbox as the research object, considering the dynamic effects of radial load, bending moment, and speed of the journal bearing, a transient tribo-dynamic coupling model of the planetary gear journal bearing was established. The dynamic meshing force and time-varying speed of the planetary gear extracted from the SIMPACK dynamic model of the wind turbine drive chains were used as the load and motion boundary inputs for the planetary gear journal bearings. The influences of the helical gear meshing bending moment, input torque, and journal bearing radius clearance on the lubrication performances of the planetary gear journal bearing were analyzed, and experimental verification was conducted. The results indicate that the dynamic meshing force and generated meshing moment  of the planetary gear will cause dynamic cyclic changes in the axial positions and deflection angle of the planetary gear, and as the load increases, the oil film/solid contact pressure and misalignment moment of the planetary gear journal bearings will gradually increase. Reducing the radial clearances of planetary gear journal bearings may effectively improve their transient lubrication performance.

In order to investigate the influences of residual stress on the service life of weld seams of laminate cooling structures, first of all, finite element simulation and experimental verification were carried out on the laser welding processes of GH3230 laminate under conventional conditions. Then corresponding regulated approaches including pre-stretching and thermotensile et al. were simulated and analyzed. Afterwards, the evolutions of temperature and equivalent stress during service periods with and without residual stress were studied respectively. The service life was later evaluated using Coffin-Manson model modified by Morrow. The results demonstrate the thermal fatigue life caused by residual stress is significantly decreased. Furthermore, the stress amplitude and the mean stress while servicing, which decreasing 70% and 25% respectively, are effectively improved using regulating approaches mentioned above. Regulating welding residual stress is of vital importance for improving the thermal fatigue life of laminate structures.

A reliability estimation model for micro-electro-mechanical system(MEMS) micro accelerometer was proposed based on the total probability theory under a multi-load environment, addressing issues related to sensitive structural fractures and material fatigue degradation. The model combined homogeneous Poisson processes and Wiener degradation processes to characterize the number of impact loads acting on the micro accelerometers within a unit time and the fatigue degradation process of the device under vibrational loads. The model accomplished reliability modeling for the micro accelerometers under generalized extreme impacts, generalized δ- impacts and generalized mixed impact conditions. The reliabilities of the three models were compared and analyzed with time, and the results of reliability calculations from the generalized mixed impact model offer more valuable insights. Furthermore, a parameter sensitivity analysis of generalized mixed impact model shows that impact intensity and impact times have significant influences on the reliability of micro accelerometers.

Based on the similarity mapping between positioning errors caused by non-geometric parameter errors and robot configurations, the robot parameter calibration configuration space was divided into multiple subspaces by clustering algorithm, then the parameter calibration was completed in each subspace. The configurations to be compensated were classified into the corresponding subspaces by similarity relation, then the robot motions were controlled according to the parameter calibration results of the subspaces, and the positioning errors caused by non-geometric parameter errors were compensated effectively. An UR5 robot was used as the calibration object for the experiments. Compared with the ordinary calibration compensation method, the maximum and average of the positioning error mode of the proposed method are reduced by 60.24% and 66.62% respectively after calibration compensation.

In order to accurately predict the remaining useful life of lithium-ion batteries and reduce the risk of battery operations, a novel model was proposed for online remaining useful life prediction of lithium-ion batteries. On the basis of historical operation data of lithium-ion batteries, six types of health indicators were extracted to characterize the degradation of batteries. The random forest(RF) algorithm was adopted to evaluate and screen the health indicators. The generalized regression neural network(GA-GRNN), which was optimized by genetic algorithm, was used to estimate the residual capacity of the battery. Then, a hybrid model combining bidirectional long short-term memory（Bi-LSTM）network model and nonlinear autoregressive（NAR） neural network（hybrid Bi-LSTM-NAR model）was used to predict the remaining useful life for lithium-ion batteries. A case study was conducted with the NASA open data. The results show that by way of screening the indicators, the accuracy of capacity estimation and remaining useful life prediction of lithium-ion batteries are ensured. Compared with the prediction results of existing methods, the prediction accuracy of the proposed hybrid prediction model is improved effectively.

For the problem of heat exchange micro-tube vibration reliability of diaphragm micro-channel pre-coolers which was one of the key components of pre-cooled air breathing combined cycle engines, the method and mathmatical model for calculating the natural vibration characteristics of heat exchange micro-tubes were developed, and the vibration modes and their mechanism of heat exchange micro-tube with the action of high speed air flow were studied. Then, the vibration modes including the vortex shedding excitation vibration, the turbulent buffeting vibration and the elastic excitation vibration were taken into account, and the reliability evalutating model of pre-coolers with heat exchange micro-tube vibration failure mode was derived. The pre-cooler heat exchange micro-tube vibration reliability of change rules were revealed. The results show that the natural vibration frequency of heat exchange micro-tube is affected by the parameters including outside diameter, pipe wall thickness, adjacent support plate spacing, material properties and so on, and the vibration modes of heat exchange micro-tube have the characteristics of sine function. Three important vibration modes including the vortex shedding excitation vibration, the turbulent buffeting vibration and the elastic excitation vibration those may happen in the heat exchange micro tubes of pre-cooler with the action of high speed air flow. And with the increasing of flow velocity of cooled working fluid, the heat exchange micro-tube vibration reliability of pre-coolers decreases firstly, and then increases and approaches a certain value. In order to avoid the resonance of heat exchange micro tubes, the structural parameters may be designed rationally with the operating profile and the flow and heat transfer characteristics may be also taken into account.

An efficient method for solving the failure probability function was proposed to address the difficulties of solving the failure probability function in reliability optimization design, such as complexity and large amount of computation. The basic idea of the proposed method was to utilize the adaptive Kriging method to construct a local surrogate model of the full space of input variables at the failure boundary. The local surrogate model was then combined with the Monte Carlo simulation method to calculate the failure probability of the structures under the specified distribution parameter samples. The functional relationship between the sample points of the distribution parameters and the structural failure probability was then fitted by the Kriging method. Finalization of the implicit function of the failure probability function expressed in terms of the Kriging model. In order to test the accuracy and efficiency of the proposed method, two examples were given to compare the computational results of the proposed method with those of the existing methods for solving failure probability functions. The results of examples show that the proposed method is suitable for solving complicated functional function problems and significantly reduces the amount of computation while satisfying the accuracy requirements.

To address the problems that the autonomous vehicle deviated from the expected trajectory at the lateral slope curve, and even losed stability owing to severe sideslipping, a dynamic adaptive control strategy for sideslip angle was proposed. To overcome the change of tire cornering stiffness caused by the changes of vertical loads of the vehicles, the load matching diagram was obtained by fitting multiple sets of data. Then, a lateral trajectory tracking controller was designed based on the model prediction control algorithm. In line with the entry speed of the vehicles into the turn, the prediction horizon was selected. Meanwhile, the transient-state and steady-state sideslip angle were selected in line with the road curve. Through online optimization, the optimal front wheel steering angle was generated. Finally, the CarSim/Simulink joint online simulation system and the real vehicles system were established for verification. The results demonstrate that the proposed control strategy may ensure that the vehicles will not have serious sideslip under the lateral slope inclination angle of around 7% and the curved road. In addition, the proposed control strategy improves the tracking accuracy of the autonomous vehicles in the lateral slope curve tracking task and makes the vehicles have good lateral stability.