In order to eliminate the restriction of the return spring stiffness on the power generation and system reliability of the energy harvesting speed bump with the full wave mechanical rectifier, a dual-speed bump energy harvester (DBEH) based on the half-wave mechanical rectifier was proposed. The device utilized a mechanical transmission module to convert the downward linear movement of two speed bumps, driven by wheels, into the one-way rotary movement of a single generator shaft, thereby converting mechanical energy into electrical energy. The unidirectional motion conversion reduced the demand for the load of the return spring. The theoretical model of the wheel excitation and speed bump dynamics was established and verified by road tests. Based on the theoretical model, the power generation performance of DBEH was studied by numerical simulation. The research results indicate that the root mean square (RMS) power and output electrical energy of the system increase with the increase of external excitation amplitude and the decrease of the spring stiffness. When the load resistance value is 7-9 Ω, the output performance of the system is optimal. Compared to reducing the gear radius, increasing the speed of the gearbox has a more significant impact on the improvement of system output. A small inertia flywheel can effectively improve the system’s capture of the mechanical energy and the conversion rate from the mechanical energy to the electrical energy.

In order to simulate the shot peening process and realize the rapid prediction of the shot peening effect, a random multi-shot pellet shot peening strengthening model was established based on Abaqus software using the discrete element method-finite element method (DEM-FEM) coupling, and the TC4 titanium alloy was used as the research object to carry out the shot peening strengthening test to verify the accuracy of the coupling model. The Box-Behnken design (BBD) method was used to design a three-factor and three-level shot peening simulation test scheme for the three process parameters of projectile size, shot peening speed and shot peening coverage.The surface residual stress value and surface roughness value were obtained by simulation analysis, and the numerical fitting was carried out by Design-Expert software. Finally, the function models between the shot peening process parameters and the surface residual stress or surface roughness were obtained, the interaction between the three factors of projectile size，shot peening speed and shot peening coverage was analyzed by the response surface method, and the influence law of shot peening strengthening effect was analyzed.The results show that the error between the results of the response surface prediction model and the simulation calculation results is less than 5%, the established response surface prediction model has high approximate accuracy and reliability，and the effective prediction of shot peening effect can be achieved by using this model.

Accidental mechanical impacts such as forklifts may lead to serious degradation of the stability of industrial rack uprights.The finite element simulation model of the upright bending damage was established based on the physical test mechanism with five types of common upright in the industry as examples, and the analysis found that even a small impact deformation (1 mm) may lead to a decrease in the ultimate bearing capacity of the upright (maximum about 37%).Compared with other impacted positions, the bending damage at the prism made the upright stability decrease more significantly.Based on this, an intelligent prediction model of the bending damage state of the upright was established by physical simulation and convolutional neural network method.The results show that the residual load capacity values of the damaged upright obtained from the prediction model agree well with the finite element simulation data (the mean absolute percentage error is 5.99%) and can be used for rapid assessment of the bending damage performance of the rack upright.

In order to study the influence of residual stress and hardness on bending fatigue performance of gear, the 20MnCrS5 steel gear with carburizing heat treatment was taken as the research object, and composite small diameter shot peening strengthening treatment was carried out to realize the gear with different hardness and residual stress states of the same material.Based on the maximum principal strain criterion, incorporating separate factors for residual stress influence and residual stress-hardness coupling influence were introduced respectively to establish the fatigue life prediction model.Through shot-peened gear bending fatigue tests, optimal values for both the residual stress influence coefficient and correction coefficient were determined.The two models’ accuracy for life prediction was contrasted, and the accuracy of these models was further verified through unshot peened gear bending fatigue test.The results show that considering only residual stress influence yielded an optimal value of 0.09 for the residual stress influence coefficient, the model achieving high life predictive accuracy.Whereas considering the effects of residual stresses and hardness, it requires a correction coefficient with an optimal value of 0.04, the model achieve even higher predictive accuracy.

Accurately predicting the fatigue life of products plays an important role in the structural strength design and reliability design of key components of electric vehicles.Starting from the measured road load spectrum of the reinforced road,a method for data processing and analysis of measured load spectrum was proposed, based on the Miner criterion, the load data of the vehicle under no-load, half-load and full load were obtained, and the key data for vibration simulation analysis and indoor bench test were obtained through time-domain frequency domain processing and damage equivalent treatment.A parallel-shaft electric drive axle was designed and developed, the statics analysis and modal analysis were carried out for key components such as the bridge shell, and the results concluded that the bridge shell would not have torsion and bending caused by road surface excitation.Based on nCode DesignLife simulation analysis software, the fatigue life and damage value distribution of the bridge shell were obtained, and the accuracy of the simulation analysis was verified by the bridge shell durability test.Based on the measured road load spectrum of the reinforced road, a 15 000 km vehicle vibration test was carried out on the vehicle vibration test bench for the electric drive axle.The test shows that the overall life and reliability of the electric drive axle meet the design requirements, and the reliability of the analysis method is verified.

Carbon fiber is increasingly used to replace conventional glass fiber in layup designs of large wind turbine blades to improve their structural strength, but the high cost of carbon fibers makes it difficult to cover the entire area of the blade.Therefore, the research of the influence of mixing ratio and relative position of carbon fibers and glass fibers on the structural performance of the blade can help to obtain higher performance and lower cost wind turbine blades.The proportion of carbon fibers and glass fibers in the corresponding position of the main beam of the blade and the relative position of layup were adjusted by Ansys software.And the structural statics, modal and buckling analyses were conducted by using a combination of computational fluid dynamic method and finite element method.The results show that the performance of the blade main beam using carbon fibers and glass fibers mixed layer can be similar to that of carbon fiber blades.When the carbon fibers near the tip of the blade can improve the blade first-order modal and buckling factors. When it is close to the root of the blade has less impact on the blade maximum stress and strain.Under the premise of ensuring the blade stability and anti-resonance performance, when the carbon fibers and glass fibers layup ratio is 3∶1 and the carbon fibers are close to the root of the blade, the overall performance of the blade is better.

Vertical axis wind turbines have gradually become a research hotspot due to their ease of scalability, but the research involving structural aspects is relatively limited.Therefore, a blade and strut composite layup design solution was proposed to meet the structural performance requirements.The computational fluid dynamics method was used to obtain the aerodynamic loads under extreme environments and loaded them onto the wind turbine surface.The finite element method was used to perform the statics and modal analysis.The results show that the proposed wind turbine blade, strut, and tower have sufficient safety under extreme loads.The maximum displacement is located at the top of the blade trailing edge, the maximum stress is located at the connection between the tower and the strut, and the maximum strain is located at the blade web in contact with the strut; the vertical axis wind turbine wind wheel still has strong torsional load characteristics under the windward condition; the wind turbine operating frequency is less than the wind turbine first-order natural frequency, and its relative difference exceeds 10%.The wind turbine will not resonate under rated conditions.

Considering cracks of various length and depth (various constraints) on the nuclear power main pipeline as the research object, through the mass acceleration application method, applying vertical load of 5 earthquake intensities and 3 real earthquakes to the nuclear power main pipeline under varying constraints respectively, and based on a method to determine the constraint related to fracture toughness of the actual structure, the calculation of constraint related fracture toughness was performed, the various constraint under various vertical earthquake loads related crack toughness was systematically studied.The results show that under the same constraint, the crack opening force curve shifts to the left with the increase of earthquake intensity, and the constraint related fracture toughness decreases gradually.With an increased crack length, the effect of earthquake intensity on constraint related fracture toughness becomes more obvious.With an increased crack depth, the effect of earthquake load on constraint related fracture toughness firstly becomes obvious, and then becomes insignificant.Under different constraints, the influence trend of the real earthquake load on constraint related fracture toughness is the same as that of the earthquake intensity, and has a certain relation with the magnitude and earthquake acceleration time history curve.

For the contact fatigue failure problem of vehicles’ hypoid gears under complex conditions, the rain-flow counting method and Goodman’s average stress equation were used to establish a contact statics model.The load-time history of the contact gear surface was extracted. And the load spectrum of hypoid gears was produced.The research focused on predicting the high-cycling fatigue life of hypoid gears based on the load spectrum.The study also utilized the finite element method to simulate gear teeth’s meshing or contact behaviour under loading conditions. Moreover, the influence mechanism of fatigue damage criterion on the gear fatigue life prediction was revealed.The proposed method is highly significant in assessing and predicting the high-cycling fatigue life of vehicles’ hypoid gears.

Based on two basic configurations of hexagonal and inner concave shapes, by utilizing experimental test and finite element simulation method, the crack expansion law of laminated porous structures under three-point bending was studied, the influence of cellular element angle of laying direction on failure mode, load capacity, and deformation of the laminated porous structures was discussed. The results indicate that the crack expansion path in the bilayer model deviates towards the weaker layer with less crack expansion inhibition capability. The weaker side experiences greater deformation,leading to a deviation of the model towards the stronger side. Under certain angle combinations, the bilayer model shows significantly improved load-bearing capacity and toughness compared to the corresponding single-layer model.