Current Issue : October-December Volume : 2026 Issue Number : 4 Articles : 5 Articles
An abundant gear fault modulation signal is closely related to the gear fault type, especially to the gear fault severity. However, the modulation signal simultaneously includes coupled frequency modulation and amplitude modulation, which hinders the precise modulation separation and modulation-based gear fault severity assessment. Therefore, a new modulation separation method is proposed, which incorporates a rotation speed extraction technique based on the extreme value search, frequency modulation mechanism and Fourier series fitting. The rotational speed induced by the gear fault is first calculated by the extreme value search, which is then combined with a frequency modulation mechanism to solve the frequency modulation signal with the Fourier series fitting. Based on the vibration modulation signal model and Fourier series fitting, amplitude modulation is finally obtained. Simulation verifies the superiority of the proposed method in aspects of effectiveness and anti-noise performance compared with other modulation separation methods. The maximum relative errors of frequency modulation and amplitude modulation parameters under a signal-to-noise ratio of 0 dB are 2.9125% and 4.1143%, respectively. Two modulation intensity indicators regarding fault-induced frequency modulation and amplitude modulation signals are presented to assess gear faults. Experiment results also demonstrate the effectiveness of the proposed method in the severity assessment of misalignment and tooth breakage. Therefore, the research provides a new technique for gear fault severity assessment based on the frequency modulation or amplitude modulation signal....
To address issues such as deformation and stress concentration that are prone to occur in pure electric passenger vehicle electric drive housings under complex working conditions, an integrated electric drive housing was taken as the research object for finite element simulation analysis and improvement tests. A finite element model of the housing was established based on ABAQUS to analyze the strain and stress of the housing and its deformation patterns under load. In response to issues such as bearing abnormal noise and seal failure caused by housing deformation, a method was proposed to enhance the structural rigidity of the housing and improve the load transfer path of the housing, which was verified through bench tests. The results showed that the maximum deformation of the improved housing decreased by 42.7%, the stress and strain in key areas were controlled within the design allowable range, and the failure rate approached zero, meeting the engineering design requirements....
This study conducted a numerical simulation of laminar flow within a cylindrical pipe using a semi-implicit method. The full Navier–Stokes equations in cylindrical coordinates were solved, with modifications to the SIMPLE algorithm to handle pressure-linked equations. We evaluated three key thermophysical parameters—dynamic viscosity, specific heat capacity, and thermal conductivity—under both constant and variable conditions in the entrance region. Due to the process’s two-dimensional, time-dependent nature, third-kind boundary conditions were used to accurately model the effects of ambient temperature, external wind, and the pipe’s geometric and physical features. From the numerical results, we analyzed the velocity field, pressure distribution, surface friction coefficient, and temperature distribution at various pipe cross-sections. These findings are of practical and scientific importance: they offer insights into the hydrodynamics and thermal behavior of the internal flow and enhance understanding of fluid flow and heat transfer, improving predictive models. This advancement supports better design and operational control in pipeline systems....
To address uneven surface hardness distribution in 65Mn external tooth friction plates after furnace quenching and disc mold tempering, we adopted an integrated quenching and forming process, using an internal-circulation mold. By simultaneously implementing pressure forming and quenching within the internal-circulation mold, the hardness uniformity of the friction plate during forming was improved, effectively suppressing warping deformation. A multi-field coupled model of the friction plate quenching in the internal-circulation mold was established to simulate the dynamic evolution of the temperature field, the microstructural transformation, and the stress field, thus obtaining the complete heat treatment response of the martensitic transformation. The experimentally observed microstructure agreed well with the simulation results. Data analysis showed that after quenching in the internal-circulation mold, the surface hardness difference of a single friction plate was reduced from 3 HRC to 0.9 HRC, and the end face runout decreased from 0.1–0.15 mm to no more than 0.06 mm, significantly improving the product’s dimensional accuracy and performance consistency....
To address the critical technical issue of difficult demolding following the die forging process of large cylindrical helical gears, a systematic theoretical analysis and process parameter investigation of the demolding technique for such forgings was conducted in the present work. Firstly, a mechanical theoretical model was established for the forging ejection and demolding procedure, and the influence mechanisms of friction coefficient and ejection velocity on ejection load, effective strain, and damage characteristics of the forging were quantitatively revealed. The results indicated that an increase in friction coefficient led to a remarkable growth in frictional resistance between the forging and the tooth-profile die cavity, which consequently elevated the maximum ejection load, effective strain, and damage value of the forging synchronously. Similarly, the maximum ejection load, peak effective strain, and maximum damage value of the forging increased sharply with the rise in ejection velocity. Therefore, it was proposed that in practical industrial production, the friction coefficient should be controlled within the range of 0.25 to 0.30 by adopting suitable high-temperature lubrication measures, and a relatively low ejection velocity should be preferentially adopted to guarantee the overall quality of the forged gear. This study provided a reliable theoretical basis and technical support for engineering applications. The optimized parameters (friction coefficient 0.25–0.30 and low ejection velocity) could be directly adopted in industrial production to reduce ejection load, lower strain and damage, and stabilize the forging quality of large cylindrical helical gears in actual die forging and demolding processes....
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