最新刊期
- 摘要：ObjectiveShear wave vibrators are susceptible to variations in coupling conditions during practical exploration, resulting in significant disturbances that lead to degraded excitation performance and unstable signal quality. Existing studies lack a systematic understanding of how coupling parameters influence the disturbance mechanisms and excitation effects of the vibrator. To address this issue, a shear wave vibrator-ground coupling dynamic model incorporating disturbance factors was developed, revealing the influence patterns of key coupling parameters on disturbances and output characteristics. This provides a theoretical basis for the structural optimization and stable excitation of shear wave sources.MethodsFirstly, based on elastic half-space theory and considering the disturbance effects induced by hydraulic overturning moments, a coupled vibration model of the shear wave source vibrator and the ground was established, and the validity of the proposed model was verified through tests. Subsequently, the influence patterns of coupling parameters on vibrator disturbances and system vibration output were analyzed on this basis.ResultsThe results indicate that, regarding vibrator disturbances, the plate area is the dominant parameter affecting disturbance sensitivity (accounting for 64% of total sensitivity), with significant nonlinear interactions existing among parameters; soil density accounts for nearly 0% of total sensitivity and can be regarded as a non-sensitive factor. In terms of vibration output, within the low-frequency range (5-20 Hz), an increase in the mass of the heavy hammer leads to insufficient output, while an increase in plate area contributes to enhancing output amplitude; a higher ground elasticity modulus can reduce energy dissipation. The findings provide a theoretical basis for suppressing shear wave vibrator disturbances and hold certain research value for improving vibrator excitation performance.关键词：Shear wave controllable source;Coupling parameter analysis;Vibration characteristics;Vibration output;Disturbance analysis16|15|0更新时间：2025-11-26
- 摘要：ObjectiveTo investigate the steering manipulation performance of automobiles under different operating conditions, this study focuses on the electric power steering system of a certain domestic vehicle model and conducts a joint simulation study using CARSIM-Simulink.MethodsFirstly, a precise dynamic model of the steering system was established through the integration of CARSIM and Simulink, selecting a linear assist characteristic curve. Subsequently, a bridge circuit pulse-width modulation proportional-integral-derivative (PID) current control strategy was designed and subjected to simulation analysis.ResultsThe results indicate that, compared to competing models employing traditional PID control, the bridge circuit pulse-width modulation PID current control strategy meets the lightweight requirements of power steering across various vehicle speeds and demonstrates superior response sensitivity. In real vehicle tests for steering lightness and intermediate position steering, the assist characteristics of this model are reasonable, and the control strategy satisfies practical usage demands.关键词：Steering system;CARSIM;Matlab/Simulink;Control strategy26|64|0更新时间：2025-11-06
- 摘要：ObjectiveAddressing the issue of data scarcity in bearing fault diagnosis of three-phase induction motors within industrial settings, where insufficient actual fault samples hinder the effective training of neural network models, a novel diffusion-convolutional neural network (DCNN) model was proposed. The DCNN model integrates the advantages of the denoising diffusion probabilistic model (DDPM) and convolutional neural network (CNN), thereby overcoming the limitations of conventional deep learning approaches in handling small-sample datasets.MethodsFirstly, the DCNN model employed the Gramian angular difference field (GADF) to transform raw vibration signals into information-rich two-dimensional time-frequency images, enhancing the representational capacity of data features. Secondly, the DDPM generator network simulated the distribution of actual fault data to generate physically meaningful, high-quality synthetic samples, thus augmenting the training dataset. Furthermore, the DCNN incorporated an improved U-Net architecture as the core denoising module; through temporal encoding and conditional embedding techniques, the model's capability to recognize complex fault characteristics was strengthened. Finally, the Wasserstein distance was utilized to minimize the discrepancy between generated and real data to optimize model training, while spectral normalization was applied to enhance model stability. The CNN classifier, trained systematically thereafter, was employed for final fault diagnosis.ResultsResults demonstrate that the proposed DCNN model exhibits superior performance surpassing traditional generative models, achieving a diagnostic accuracy of 99.95%, representing a significant improvement over conventional methods. These findings validate the efficacy and excellence of the proposed model in addressing small-sample fault diagnosis challenges.关键词：Fault diagnosis;Diffusion-convolutional neural network;Denoising diffusion probabilistic model;Virtual sample generation;Three-phase induction motor bearings14|50|0更新时间：2025-09-19
- 摘要：ObjectiveAiming at the problem of significant vibration in the roller movable teeth due to long-term impact loads, a novel lattice roller movable teeth was proposed based on the hollow roller structure.MethodsFirstly, the impact resistance of four lattice structures was analyzed through equivalent stiffness prediction and impact tests, determining the optimal lattice structure and the structural parameters of the lattice roller movable teeth. Subsequently, simulation analysis was conducted to investigate the equivalent stress and vibration characteristics of solid roller movable teeth, hollow roller movable teeth, and lattice roller movable teeth. Finally, a vibration characteristic testing platform of roller movable teeth was established, and the vibration accelerations of different types of movable teeth were comparatively analyzed.ResultsThe results indicate that the proposed lattice roller exhibits a 28.72% reduction in equivalent stress compared to the solid roller and a 3.96% reduction compared to the hollow roller. Additionally, the peak vibration acceleration of the lattice roller movable teeth is significantly lower than that of the solid and hollow roller movable teeth, demonstrating excellent vibration damping performance. The test results align with the simulation trends, verifying the reliability of the simulation model and the accuracy of the test results. The findings of this study can provide a reference for the structural design of vibration reducing movable teeth.关键词：Roller movable teeth;Lattice structure;Impact test;Equivalent stress;Vibration acceleration;Movable teeth transmission17|30|0更新时间：2025-07-03
- 摘要：ObjectiveTo effectively address numerical instabilities and enhance optimization performance for achieving desirable results in continuum structural topology optimization problems, an improved strategy based on the variable density method is proposed.MethodsFirstly, in response to the limitations of the solid isotropic material with penalization (SIMP) model and the rational approximation material properties (RAMP) model in terms of penalty efficiency and convergence speed, an improved interpolation model was proposed. Secondly, the Sigmund sensitivity filtering method was employed to eliminate checkerboard patterns and mesh dependency phenomena. Finally, a grayscale suppression operator was designed and integrated into the optimality criterion (OC) method for updating design variables.ResultsNumerical studies have demonstrated that this scheme not only improves penalty efficiency and accelerates convergence speed but also eliminates completely grayscale elements, resulting in optimized structures with clear boundaries.关键词：Variable density method;Topological optimization;Interpolation model;Grayscale suppression102|65|0更新时间：2025-05-28
- 摘要：ObjectiveTo rapidly and accurately assess the fatigue life of in-service concrete pump truck boom structures, a fatigue life prediction method based on an ensemble learning model is proposed, utilizing monitoring data and machine learning techniques.MethodsFirstly, a concrete pump truck information acquisition system was employed to obtain functional and performance characteristics during the operational phase of the pump truck. Through data preprocessing and transformation, a sample dataset of stress range under typical working conditions, denoted as O, was generated. From the perspective of complementary advantages, a Stacking model for stress range prediction was constructed using gradient boosting decision tree (GBDT), random forest (RF), extra trees (ET), adaptive boosting (Adaboost), and sequential learners. Subsequently, kernel density estimation sampling (KDES)was utilized to extract functional characteristics of the pump truck's operation within specific service cycles, which were then input into the established Stacking model to predict the stress range dataset for the boom structure. Furthermore, using Matlab as the computational platform and integrating fracture mechanics theory, rapid predictions of fatigue life for the boom structure were achieved. Reliability analysis was conducted to ascertain the reliability of the corresponding fatigue life predictions, thereby enhancing the credibility of the results. Finally, taking a 56X-6RZ model concrete pump truck from a certain company as an example, the feasibility of the proposed method was validated through comparisons with single machine learning models.ResultsThe proposed method provides a theoretical basis for determining maintenance cycles and retirement decisions for pump trucks based on fatigue life assessments.关键词：Fatigue life prediction;Integrated learning model;Fracture mechanics;Nonlinear boom structure;Concrete pump truck55|56|0更新时间：2025-05-13
- 摘要：ObjectiveTo achieve the goal of accurately and effectively assessing the structural strength and the safety and health status of battery cells during bottom crash tests of battery packs.MethodsA numerical test model was established by using Abaqus software based on explicit dynamics theory and the finite element method, this model was used to calculate the displacement, equivalent plastic strain, and energy distribution of the structure.ResultsThe test results showed that the deformation shape, intrusion amount, and strength status of the crashed components were highly consistent with the simulation results, it indicates that the simulation model could accurately simulate and represent the dynamic response characteristics and damage mechanisms of the battery pack structure. Additionally, the mechanical response characteristics and energy distribution of the system and components during the test were studied through simulations. It was demonstrated that the system adhered to the principle of energy conservation. The simulation results indicated that 80.96% of the total energy was converted into strain energy in the crashed components, and the energy absorption ratio of the crashed components was directly proportional to the intrusion depth, it reveals the improvement direction for the underbody protection design, which is to reduce the intrusion of battery cells by designing an underbody protection solution with a high proportion of energy absorption. Furthermore, the maximum impact force 27 299 N of the ball head on the bottom of the battery pack was obtained, providing a theoretical reference for the mechanical performance design of bottom protection schemes for battery packs.关键词：Power battery pack;Bottom crash;Intrusion amount;Energy absorption proportion;Bottom safety protection163|373|0更新时间：2025-02-13
- 摘要：In order to study the effect of coupling between inner and outer defects of high⁃speed train axle on fatigue crack initiation， a multi⁃crystal finite element model of high⁃speed train axle was established on mesoscopic scale based on crystal plasticity theory The stress field and structural deformation around the inner and outer defects of axle were analyzed by tensile and impact tests， and the effect of inner and outer defects coupling on fatigue crack initiation was investigated Based on the characteristics of stress distribution and plastic strain energy density distribution， the crack initiation location was predicted. The results show that the interaction between two defects was stronger when the inner defect was closer to the outer defect， and the crack initiation was promoted when the inner inclusion defect was at the center of the model， the interaction between the two defects was minimal， and the external defects were the main factors leading to crack initiation.关键词：Crystal plasticity theory;Defect coupling;Crack initiation;Stress field;Plastic strain energy densi55|127|0更新时间：2024-11-01
- 摘要：In order to investigate the influence of the coupling variable stiffness characteristics on the vibration behavior of the shaft system， the motor rotor⁃coupling⁃crankshaft⁃bearing of the compressor was taken as the object of study， and the Lagrange method was used to construct a coupled dynamics model of the bending⁃torsion of the shaft system. The results show that the variable stiffness characteristics of the coupling will cause the phase space to appear as "sawtooth" fluctuations， but the law of variation of the shaft center trajectory was basically unaffected. With rotational speed as the control parameter， the variable stiffness characteristic induces nonlinear behaviors such as chaos and bifurcation and causes a rightward shift of the resonance peak and an increase in the amplitude of the unstable region. The degree of phase space fluctuation decreases with the reduction of the axial tile clearance， and the area of the non⁃contacting region in the x and y directions shows a decreasing trend. The research results can better predict the bending⁃torsion coupling vibration behavior of the shaft system and guide the selection of the operating speed of the shaft system.关键词：Compressor shaft system;Bending⁃torsion coupling;Hardening stiffness;Non⁃linear dynamics;Bifurcation109|142|0更新时间：2024-10-10
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PARAMETER ESTIMATION AND CONFIDENCE LIMIT CALCUALTION METHOD OF THREE-PARAMETER WEIBULL DISTRIBUTION
摘要：A correlation-regression method was proposed to solve the problem of low accuracy of parameter estimation and confidence limit calculation of the three-parameter Weibull distribution.The method was combined by the correlation coefficient method （Fu method） and the nonlinear regression method which makes full use of the convenience of Fu method and the excellent estimation effect of the nonlinear regression method in estimating the three-parameter Weibull distribution.In order to verify the effectiveness of the proposed method，the correlation-regression method，Fu method and Method combining maximum likelihood estimation and empirical formulae (referred to as the “MMPDS method”） were applied to the parameter estimation and confidence limit calculation of the data distribution of a certain alloy strength value with different sample sizes，and calculation consequence of different methods was compared and analyzed.Results show that the correlation-regression method has highest parameter estimation and confidence limit calculation accuracy among the above methods.When the sample size is less than 100，its advantage is more significant，and it can accurately calculate the parameters and confidence limits of the Weibull distribution.关键词：Weibull distribution;Parameter estimation;Confidence limit42|283|0更新时间：2024-06-27 - 摘要：Reinforced shell structure is widely used in aerospace load-bearing structures because its high specific stiffness and specific strength.By considering the uncertainty and risk factors in the structural parameters，the Reliability-Based Design Optimization （RBDO） can avoid the overly conservative design of the structure and ensure its reliability and safety.An efficient RBDO method based on adaptive agent model was proposed.This method solves the problem of lightweight design of reinforced shell structure under buckling reliability constraints.The adaptive addition of sample points was implemented through the expected feasibility function criterion，and the discrete variables was continued by constructing piecewise functions.This increases optimization efficiency while ensuring the reliability of design results.Finally，the effectiveness of the proposed method is verified by comparing the RBDO results with the deterministic optimization results.关键词：Reinforced shell;Reliabilitybased design optimization;Adaptive surrogate model;Expected feasibility function52|85|0更新时间：2024-06-26
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