In the course of real operation, the drive axle housing is likely to undergo fatigue failure due to prolonged exposure to cyclic alternating loads.To determine whether the drive axle housing of a commercial vehicle’s wheel-side electric motor complying with fatigue life requirements at the design stage, a three-dimensional model and finite element model of the drive axle were established. Firstly, an initial inertia release analysis was performed，indicating that its static strength and stiffness met the requirements.Secondly, based on this foundation，utilizing nCode DesignLife software, using the nominal stress method in conjunction with the material’s S⁃N curve and fatigue loading curve, a new automotive industry standard was employed to predict the fatigue life of the housing under multiple conditions，such as vertical bending fatigue,braking fatigue and lateral fatigue.The results revealed that the fatigue life of the drive axle housing under braking fatigue and lateral fatigue conditions did not meet the requirements set out in the standard, necessitating structural optimization. Finally,reinforcement optimization was performed on the drive axle housing. The results show that, through optimization，the maximum stress of the drive axle housing is reduced by 95.8 MPa and the maximum deformation is decreased by 1.064 mm under the maximum impact conditions.Additionally, the minimum fatigue life under three different fatigue conditions is improved respectively by 1.076 million cycles, 289 000 cycles, and 497 000 cycles, exceeding the requirements stated in the standards.This validates the feasibility of optimizing the drive axle housing structure, effectively shortening and reducing the research and development cycles and associated costs.

To investigate the vibration performance of RV reducers and analyze the fault identification, the torsional vibration test bench for RV reducers was built.Based on the mechanical structure and transmission principles of RV reducers,the vibration frequencies under different operating conditions were calculated.The vibration signal of RV reducers of superior and inferior products was collected, and the acceleration signal of the torsional vibration under different speeds and swerves was collected.The torsional vibration signals were decomposed using the variational mode decomposition (VMD) to obtain the intrinsic mode function (IMF).The results demonstrate a high correlation between the extracted IMF features obtained through VMD and the vibration frequencies observed during the operation of RV reducers.Furthermore, by comparing the spectrum of IMF, the reasons behind the abnormal vibration in inferior RV reducers were identified.Ultimately, it is determined that the abnormal vibration in inferior RV reducers were caused by the excitation from the interaction between the auto rotation of the planetary gear and the crankshaft or the revolution of the cycloid gear.This study provides valuable insights for enterprises aiming to improve the transmission accuracy and product quality of RV reducers.

Body centered cubic (BCC) structure has excellent mechanical properties, but the stress concentration phenomenon at the nodes limits its further development in mechanical properties. At present, the method of adding spherical nodes or variable cross-section pillars is commonly used to alleviate stress concentration at nodes and achieve strengthening design of lattice structures, but there is a lack of research on the influence of the volume ratio of nodes to pillars on the strengthening effect. A new type of variable cross-section pillar based on trigonometric function reduction is designed, and a variable cross-section body centered cubic lattice (VC-BCC) lattice is designed. Dynamic node design is achieved by directly connecting the pillars to explore the optimal node to pillar volume ratio. Theoretical formula estimation of the volume of VC-BCC lattice is carried out, and based on the Timoshenko beam model, the equivalent elastic modulus of VC-BCC lattice is theoretically analyzed. A simplified model is established using the method of equivalent cross-section. Finite element simulation analysis was conducted on VC-BCC lattice with different proportions of node pillars, and lattice specimens were manufactured using selective laser melting technology for quasi-static compression testing. The experimental results show that there is little difference between theoretical calculations and simulation analysis. The maximum stress of the VC-BCC lattice structure is significantly reduced, and the equivalent yield strength is significantly improved. In all analyses, the VC-BCC lattice structure with a variable cross-sectional parameter of 0.6 exhibited excellent performance and had the best overall mechanical properties.

To solve the problems of high-power downstream belt conveyors in large inclination angles, high belt speed conditions which are very prone to flying cars and belt breakage, a kind of disk-type adjustable permanent magnet damping roller device was put forward by adjusting the size of the area of engagement between the permanent magnet and the coil to realize the braking adjustment. The Maxwell software was used to study the transient magnetic density distribution law of the disk-type permanent magnet damping device under stable conditions and the changing law of damping torque by different air gap thicknesses, and the test bench was built for test verification. The results show that with the increase of the air gap thickness, the magnetic density gradually increases, up to 2.1 T. The damping moment increase when air gap thickness is from 1 mm to 2 mm, the damping moment decrease when from 2 mm to 3.5 mm. The research can provide data support for improving and optimizing high-power downstream belt conveyors.

Taking multicellular square tubes as the research object, the influence of the evolution of cross section shape on the energy absorption of the structure of multicellular square tubes was studied by using the verified finite element model. The results show that, under the same mass conditions, the multicellular tubes with the best energy absorption k=0.25 increased by 26.34% compared with those with the worst energy absorption k=0.40. Under the same wall thickness, the energy absorption with k=0.25 and the specific energy absorption of the multicellular tubes were 311.69% and 73.80% higher respectively than that of the ones with k=0, and the crushing force efficiency was increased by 52.51%. Finally, the parametric study of shape coefficient and wall thickness on the structural crashworthiness was carried out systematically. The research results can provide a reference for innovative design of multicellular square tubes.

As the key equipment for collecting signals, the coupling performance of oil and gas exploration geophone and earth vibration affects the quality of collected signals and determines the exploration accuracy. In order to improve the exploration ability of the geophone, the structure of the tail vertebra of the geophone was taken as the research object. Based on the single-degree-of-freedom coupling vibration theory, a vibration model for the coupling of the tail vertebra of the geophone and the earth surface under the sweep frequency signal was proposed. The acceleration,velocity and displacement response of the received signal of the tail vertebra of the geophone under the sweep frequency were extracted and analyzed.The coupling degree evaluation index of the mean value of vibration displacement and the standard deviation of vibration acceleration was established, and the coupling degree response of the tail vertebra of the geophone and the earth was mastered.Through the geophone receiving test, the maximum error between the acceleration signal received by the geophone tail vertebra and the acceleration signal received by the test was less than 15%, which verified the correctness of the model and method. Finally, based on the response surface method, the key parameters of the length and radius of the tail vertebra under different shapes were optimized. The results show that the coupling degree of the tail vertebra under the triangular pyramid shape is the best. The coupling mean value of the displacement of the optimized ground-geophone tail vertebra is reduced by 7.94%, and the standard deviation of the acceleration is reduced by 6.42%, which effectively improve the ability of the geophone tail vertebra to receive signals.

In practical engineering, gearboxes are subject to complex and variable operating environments, which hinder the ability of a single vibration signal to accurately and effectively represent fault information under different working conditions. To address this issue, a gearbox fault diagnosis method for variable working conditions based on weighted subdomain adaptive adversarial networks was proposed. Initially, a multi-source heterogeneous signal fusion strategy was employed to transform vibration signal spectrograms, current signal Gramian matrices, and infrared thermograms into a multi-channel dataset, offering diverse perspectives on gearbox operational states. Subsequently, a self-calibrated convolutions network (SCNet) incorporating an efficient channel attention (ECA) mechanism acted as a feature extractor, dynamically adjusting the interactions and dependencies between multi-source heterogeneous signals to balance the scale differences between the source and target domain heterogeneous data. Concurrently, during adversarial training of the feature extractor and domain discriminator, maximum mean discrepancy (MMD) and linear discriminant analysis (LDA) were introduced to measure the domain alignment degree of the current cross-domain task feature representation and the diagnostic task decision boundary. A dynamic balancing factor was constructed to real-time adjust domain alignment loss and class discriminability loss, effectively aligning each class space between the source and target domains. Finally, validated by a collected gearbox fault dataset under variable operating conditions. The results show that the proposed method achieves diagnostic accuracy exceeding 95% across different conditions, demonstrating its feasibility and effectiveness.

In order to solve the problem of the accuracy of the random vibration transmissibility calculation of airborne electronic equipment, the basic STEINBERG sinusoidal vibration transmissibility model and the IRVINE random vibration transmissibility model were firstly verified through tests, and it was found that there was room for improvement in the accuracy of the IRVINE random vibration transmissibility model. Therefore, on the basis of the "Three-interval method", the effects of 4σ and 5σ transient acceleration of random vibration were taken into consideration, and a more comprehensive"Five-interval method" was proposed; then, the structural fatigue coefficients of the model were corrected by combining with the characteristics of the airborne electronic equipments. The results show that the error between the proposed random vibration transmissibility calculation model and the measured value is less than 5%, which is closer to the measured value,proving that the proposed model is more accurate.

High-speed machining technology by improving the cutting speed and feed rate to improve the material cutting rate, machining accuracy and machining quality, is one of the main ways of modern processing. Therefore, to ensure the stability of high-speed machining is the basis of application of high-speed machining. Firstly, based on the traditional stability analysis, the influence of feed rate on the static cutting thickness was further considered, the stability model related to feed rate and radial cutting depth ratio of tool was established, and the stability of high-speed milling was analyzed by combining stability variance ratio. Secondly, based on the single factor variable feed rate test, a filter was designed to filter the frequency component of the spindle speed. The variance ratio between the filtered signal sequence and the original signal sequence was used to analyze the milling stability changes of the continuous variable axial depth test, and the validity of the analysis method considering the feed rate to affect the stability of high-speed milling was verified. The results show that the proposed method can determine milling stability more accurately for high-speed machining with small radial cutting depth. And the axial cutting depth of unstable cutting limit changes slightly with the increase of feed rate, and the feed rate will aggravate the instability of milling system.

To explore the impact of key parameters of brake pads on the dynamics characteristics of the braking system,the test research based on a friction testing machine with a slider-disc structure was conducted.The test research of the impact of key parameters of brake pads (rotation speed, pressure, mass, braking radius, etc.) and the braking environment (dry friction, wetness, sand) on the stability of the braking system was carried out. At the same time, a dynamics model of the brake pad braking system was established，compared with test results using the mathematical tool of autocorrelation coefficient. The results show that the key parameters of brake pads have a significant impact on the dynamics characteristics of the braking system; under different conditions of brake pad mass, tribological parameters, brake pad radius, and braking environment; the chaotic characteristics of the braking friction force signal show a trend of expansion or contraction; the chaotic vibration can be suppressed by adjusting the key parameters of brake pads. This study can provide reference for optimizing the braking strategy and reducing noise and vibration in brake pad systems.