Residual stress is the main factor affecting the machining performance and service life of brazed diamond tools. At present, in simulations, diamond is often simplified as a spherical shape, which leads to changes in the degree of structural constraint at the joint, resulting in significant differences between the calculated results and the actual situation. The evolution law and distribution characteristics of residual stress in vacuum-brazed diamonds, as well as the influence of residual stress on wear resistance, were investigated. Firstly, the geometric model of the diamond coating was optimized based on macroscopic morphology. Then, a finite element model of the stress field of vacuum brazed diamond coating was established using thermal elastoplastic mechanics, and the stress field distribution law of the diamond coating was obtained. Subsequently,residual stress measurement experiments were conducted on diamond and nickel based coatings to verify the reliability of the model. Finally, the influence of residual stress on the wear resistance of diamond coatings was explored through wear-resistant weight loss experiments. The main form of wear failure of diamond tools is diamond detachment caused by insufficient grip of the coating on diamond abrasive particles. The diamond wrapped by the brazing material layer is mainly affected by residual compressive stress, which increases the coating’s grip on the diamond. The higher residual stress inside the nickel based coating can also effectively suppress the wear-resistant failure mode of coating peeling.

Aiming at the issues of fracture and weight reduction in the wheel hub motor housing of an off-road vehicle, a structural strength finite element simulation analysis and structural topology optimization design were conducted. Firstly, a multi-body dynamics model of the entire vehicle was established, and a simulation analysis was performed to determine the load boundary conditions of the hub motor housing. Secondly, based on the spatial position relation between the housing and interconnected structures, a finite element model of the motor housing and suspension system was constructed for dynamic simulation analysis. Subsequently,using the OptiStruct software platform,with the objective of minimizing structural compliance and constraints on volume ratio before and after optimization as well as the maximum stress, a mathematical topology optimization model for the motor housing under various typical operating conditions was established and solved to obtain the optimal material distribution scheme. Finally, the optimization results were verified by simulation. The results indicate that compared to the existing design,the optimized hub motor housing structure experiences a stress reduction of over 40% and a weight reduction of 2.6%. It addresses the original fracture issue and eliminates the phenomenon stress concentration, thus providing the valuable reference for the design of similar hub motor housing structures.

Aiming at the problem of the weld fatigue test of the new energy vehicle subframe, a program load spectrum compilation method based on the failure dominant load was proposed. Firstly, the finite element model of the rear subframe was established, and the stress distribution under unit load was coupled with the load of each connection point. The structural stress method was used to evaluate the fatigue life of the subframe welds, and six dangerous points that were easy to fail were selected. Secondly, by comparing the load damage of each connection point, the failure dominant connection point corresponding to the weld dangerous unit was determined. Then, the failure dominant load was determined by the principal stress analysis, time domain correlation and uniaxial damage contribution at the weld, so as to reduce the dimension of the multi-axial load and reduce the difficulty of the bench test loading. Finally, a pseudo-damage matrix was output based on the failure dominant load, the characteristic working conditions and their proportions were selected to obtain the load spectrum of the fatigue accelerated test program, and the minimum number of cycles was determined according to the principle of the damage equivalence. The numerical simulation results show that the program load spectrum can reproduce the damage of dangerous points and has a high acceleration coefficient, which verifies the effectiveness of the accelerated test spectrum.

To study the response characteristics of the hollow extruded profile of the vehicle after the collision, the generalized incremental stress state-damage model (GISSMO) was introduced and the finite element simulation was carried out. Firstly, based on the test results of 6082-T6 aluminum alloy, the dynamic and static mechanical properties and fracture behavior under different stress states were characterized by the modified Johnson-Cook (MJC) model and DF2016 model respectively. Secondly, the parameter calibration of GISSMO was carried out based on the combination of LS-OPT soft ware and manual optimization. Then, according to the mesh size effect, the mesh size dependence correction was carried out, and the effectiveness of the model and correction were verified by comparison between the experiment and simulation. Finally, the impact simulation analysis of a hollow extruded profile on the side wall of a vehicle body was carried out, and the impact of material damage and fracture on the simulation results was compared. The results show that GISSMO can more accurately reflect the response of profiles under longitudinal impact than without considering the damage and fracture of materials.

In practical operation, the loads borne by electric excavators often exhibit significant non-stationary random characteristics, leading to complex vibration phenomena of the battery pack, which directly affects the safe and reliable operation of the battery pack. To address this issue, the characteristics of road excitation, plunger pump pressure pulsation excitation, and impact excitation on electric excavators under complex working conditions were investigated. The vibration transmission paths under various excitations were analyzed, a dynamic model of the battery pack was established, the vibration characteristics of the battery pack under non-stationary random excitation were revealed, and case studies were conducted for analysis and verification. The research shows that reconstructing road excitation signals based on wavelet transform and Grey Wolf Optimization-Variational Mode Decomposition (GWO-VMD) signal analysis algorithm can effectively reflect the characteristics of road excitation. The road excitation borne by electric excavators under driving conditions exhibits significant non-stationary characteristics. Under non-stationary random excitations such as road excitation, the battery pack of electric excavators produces complex and changeable vibrations, whose power spectral density of dynamic response changes significantly with time, showing obvious non-stationary random characteristics.This study provides a reference for the safe and reliable operation of battery packs in electric excavators.

In order to study the strain softening phenomenon of ultra-fine grain (UFG) metal materials under uniaxial tensile loading, a modified model considering the effect of residual internal stress was proposed based on the classical crystal plasticity constitutive model, and the specific form of residual internal stress and its evolution were programmed into the user subroutine. The uniaxial tensile test data were fitted to verify the validity of the model, and the finite element simulation results of crystal plasticity were compared with and without the residual internal stress. The results show that the simulation results obtained by using the modified crystal plasticity constitutive model are in good agreement with the experimental results, indicating that the modified crystal plasticity constitutive model can effectively capture the strain-softening phenomenon of UFG metal materials, and the simulation results show different properties under the two conditions whether the residual internal stress is taken into account. It is reasonable to explain the strain softening phenomenon of UFG metal materials from the perspective of the formation and action of residual internal stress.

Aiming at optimizing the gear surface modification process, the influence of ion nitrogen implantation on the bending fatigue strength of carburized and quenched gears was studied.Using low-carbon alloy steel 18CrNiMo7-6 carburized and quenched gears as the matrix, nitrogen ion implantation treatment was carried out through a radio-frequency plasma-assisted ion implantation system. The root metallography, hardness gradient, residual stress distribution, and bending fatigue properties of ion-implanted gears and unimplanted gears were systematically compared. The results show that the ion nitrogen implantation process increases the root hardness from 695 HV0.1 to 780 HV0.1, an increase of 12.2%; the hardened layer depth decreases from 1.50 mm to 1.41 mm, a reduction of 6.0%; and the surface residual stress decreases from -400 MPa to -286 MPa, a reduction of 28.5%. Based on the R-S-N equation fitted by bending fatigue tests, under 99% reliability, the fatigue life of ion-implanted gears is only 12.3%-19.3% of that of the control gears, with the failure mode dominated by brittle fracture and accelerated crack propagation rate. The study indicates that although ion nitrogen implantation can delay crack initiation through surface strengthening, the excessively shallow hardened layer and reduced residual stress lead to insufficient crack propagation resistance, ultimately weakening the bending fatigue life of gears.

This article took the folding section cam linkage mechanism of a carton folding machine as an example.Firstly, a preliminary design of the cam was carried out based on actual working conditions. Then, combined with the analytical method designing the cam mechanism based on the allowable pressure angle of the cam, a mathematical model was established with the swing rod angle and the center distance between the cam and the swing rod as design variables. Using the NSGA-Ⅱ optimization algorithm, perform multi-objective optimization design on the cam linkage mechanism and select the optimal solution from the generated Pareto solution set. Based on the optimization results, the preliminary design of the cam linkage combination mechanism was adjusted, and the contour of the cam was obtained through Matlab programming,verifying that the optimized cam pressure angle met the allowable pressure angle. Finally, simulation analysis was conducted on the optimized cam linkage mechanism using Adams software. It is found that the displacement, velocity, and acceleration of the blade movement meet the design requirements, verifying the correctness and feasibility of the optimization results. At the same time, it also provides a reference method for the optimization design of other cam linkage mechanisms.

In order to improve the high temperature wear resistance and extend its service life of 304 stainless steel, the high temperature wear-resistant NiCrAlY/Co coating was prepared on the surface of 304 stainless steel by the laser cladding.The morphology, phase composition and microhardness of the coating were analyzed.The tribological properties of 304 stainless steel and NiCrAlY/Co coating at different temperatures（the room temperature to 800 ℃) were studied, and the wear mechanism was analyzed. The results show that the coating is metallurgically bonded to the 304 stainless steel substrate; the coating is mainly composed of γ-Co,(Cr, Ni) and AlNi₃ phases; the average microhardness of the coating（303 HV) is about 1.6 times that of the substrate（194 HV); Compared with the substrate, the coating has a smaller friction coefficient at 200-600 ℃,the friction coefficient is comparable at 800 ℃, and the lowest friction coefficient of the coating is 0.5 at 600 ℃.The wear rate of the coating from the room temperature to 800 ℃ is lower than that of the substrate，and the lowest wear rate is 1.91×10^-5 mm³/(N·m) at 400 ℃, which is about 1/3 of the substrate, indicating that the NiCrAlY/Co coating improves the high temperature wear resistance of 304 stainless steel. At medium and low temperatures，the wear mechanism of the substrate is mainly abrasive wear and adhesive wear, and the wear mechanism of the NiCrAlY/Co coating is mainly abrasive wear and gradually slight adhesive wear.At 800 ℃, the wear mechanism of the substrate is plastic deformation, and the wear mechanism of the coating is oxidation wear.

In order to ensure the industrial robot realizes the reliability goal, reliability allocation is a task to be accomplished in its manufacturing design stage. According to the characteristics of industrial robots, such as complex structure, high uncertainty, few samples, and failure correlation between component parts, a reliability allocation method for industrial robot systems based on BP neural network and Pythagorean fuzzy numbers was proposed. Using Copula function to establish a system reliability model, the failures of industrial robots were classified into three levels, the system level, the subsystem level, and the component level. By using the back propagation (BP) neural network, the system reliability,subsystem structure importance and subsystem complexity were taken as the input variables to complete the system-to-subsystem reliability allocation. The Pythagoras fuzzy number was introduced to score the influence factors of importance,environmental condition, technical level, maintainability, cost sensitivity and complexity, complete the reliability allocation from the subsystem level to the component level.The results show that the methodology achieves reliability goals and ensures reliability growth.