Structural vibrations have a significant impact on the stability and performance of mechanical systems. In this paper, a structure-energy flow cooperative topology optimization design method is proposed for the efficient generation of vibration transfer paths, aiming at vibration damping and fast energy transfer in mechanical structures. A mathematical model for structure-energy flow collaborative optimization design has been established, and the formula for energy transfer in three-dimensional mechanical structures has been derived. Using the finite element energy flow method, vibration and energy field analyzes of the structure have been performed. The energy flow formula for the three-dimensional structures has been developed to solve the distribution of energy flow, optimize the vibration transfer paths through transfer rate optimization, and provide a visual representation of the results. Two case studies validate the effectiveness of the proposed method. In the case of a three-dimensional steel plate, the SECO-optimized structure achieves a 30.4 % energy transfer rate (32.3 % experimentally), outperforming both SIMP-optimized (27.1 %) and original (25.6 %) structures. It also reduces the maximum vibration velocity to 7.12 mm/s, representing improvements of 15.5 % and 20.6 %, respectively. In the vibration table platform application, the method reduces energy density to 2.39 x 10-7 dB/mm2, representing 44.5 % and 23.6 % reductions compared to original and SIMP-optimized structures. The associated vibration velocity is also reduced by 31.6 % and 21.9 %, respectively. Experimental validation confirms these improvements, showing a 20.6 % vibration reduction and a 6.7 % energy transfer enhancement in physical tests. Collectively, these results verified that the method can achieve structural vibration reduction effectively.
In order to simulate and predict the road noise of electric vehicles,a road noise simulation analysis method based on road profile spectrum was proposed.First,based on scanning the proving ground NVH road profile,an elevation data spectrum representing the scanning proving ground NVH road profile was established.Then,converting the elevation data spectrum into the road excitation spectrum required for road noise simulation analysis,and the full vehicle finite element model was established.The road noise of electric vehicles was simulated and analyzed,the interior noise obtained from the simulation analysis was compared with the experiment,the reliability of road noise simulation analysis based on scanning proving ground NVH road profile spectrum was verified.The method using actual scanned road profile as excitations input to simulation can effectively predict the road noise and vibration during the vehicle development early stage,and has important significance for road noise study.
In view of the low precision and slow speed of the traditional manual detection of steel surface defects,the YOLOv5s algorithm was applied to the experiment of strip steel surface defect detection,the original YOLOv5s algorithm network was modified,and the new C3 structure was used to reduce the calculation amount of the model and improve the calculation speed.The modification on the PANet network,adding the NAM attention mechanism before the detection head,improves the accuracy of network prediction,and also speeds up the convergence speed of the entire network.From the test results,it could be concluded that the accuracy and convergence speed of neural network detection were improved,and it could quickly and accurately locate the defect position in the picture.
Aiming at the problems of excessive model parameters,non-smooth motion path and low parking accuracy in the research of automatic parallel parking path planning in Cartesian coordinate system,parallel parking path planning in Frenet coordinate system was proposed.In the Frenet coordinate system,the parallel parking path planning was studied.The parking motion was decoupled into horizontal and vertical axis motion.Two different polynomial curves were analyzed,and then two mutually perpendicular directions were coupled.The motion was compared with the double circular arc parking trajectory fitted by the quintic polynomial in the conventional coordinate system.The vehicle parking path planned in Frenet coordinate system was smoother and more comfortable,which reduced the amount of calculation and provided a new direction for parking path planning.
Based on the traditional anti-roll hydraulic interconnected suspension system,by designing a stroke-sensitive groove on the hydraulic cylinder,the reciprocating movement of the piston position in the groove was used to realize adjustable damping.MATLAB/Simulnik was used to establish a complete vehicle model of the hydraulic interconnected suspension with this structure,and the accuracy of the model was verified through the stability experiment.Finally,the simulation model was used to carry out the simulation analysis of serpentine motion,double-line shifting movement and the random road excitation test.The results showed that,compared with the traditional anti-roll hydraulic interconnected suspension,the stroke-sensitive hydraulic interconnected suspension could effectively improve the ride comfort of the car.
With the increasing development of new energy vehicle market,the demand of vehicle steering system is increasing.The optimal design of the steering universal joint is of great practical significance to the overall safety,comfort and environmental protection of the steering system.Taking the steering universal joint of a new energy mini-car as the research object,a three-dimensional model was built by SoildWorks software,and the three-dimensional model was imported into ANSYS finite element software for topology optimization design.Compared with the initial model,the mass of the optimized model was reduced by 40%under the condition of keeping the load and constraints unchanged.By comparing the static characteristics before and after optimization and the modal shapes of the first three orders,it was found that the comprehensive influence of optimization was less than 10%,and the purpose of optimal design of steering universal joint was achieved.
In order to reduce the energy consumption of the whole vehicle under the premise of ensuring the power of the vehicle,the comprehensive shifting law of pure electric passenger vehicles was optimized.Taking the clutchless two-speed automatic transmission(AMT)as the research object,the traditional comprehensive shift rule of 40%accelerator pedal opening as the critical point was established.By establishing a comprehensive optimization model with speed as optimization variable,energy consumption and acceleration as optimization objectives,the improved immune particle swarm optimization algorithm was used to optimize the traditional comprehensive shifting law to get a new comprehensive shifting law.A simulation model of the shifting law of the two gears AMT was built in Simulink,and the comprehensive shifting law before and after optimization was simulated and verified in the WLTC working condition.The simulation results showed that the power performance was guaranteed while energy consumption was reduced by 8.825%.The research results provide a new way of thinking for the formulation of shifting rules of pure electric vehicles.
In order to improve the dynamic stability of quadruped robot under strong lateral impact,an emergency gait switching strategy and an attitude adjustment compensation strategy were proposed to resist the impact.Trot gait was taken as the basis and posture angle of the body as the monitoring index.When the robot was subjected to a large impact,the trot gait would be changed to the emergency gait.Step length in the corresponding direction would be calculated based on the velocity acceleration in all directions caused by the impact force.The foot compensation was calculated by attitude adjustment and the next foot coordinates were obtained comprehensively.Finally the leg was swung to the desired foot position to offset the lateral impact velocity.The above control strategy was used to realize the stability control of the quadruped robot under lateral impact.The feasibility and effectiveness of the control strategy were verified by MATLAB and ADAMS co-simulation,and the ability of the quadruped robot to resist external interference was significantly improved.
Fused deposition(FDM)3D printers are formed by melting and accumulating filaments.When the diameter of printing filaments fluctuates,the machine itself cannot adjust dynamically,but continues to work until the end of printing.The feed error caused by filament errors in the FDM printing process was studied,and a feed detection system based on CCD sensor was proposed.The CCD sensor module was used to measure the diameter of filaments in the printing process.Then,the measured value was compared with the theoretical value to dynamically adjust the feed rate and improve the printing quality.In order to verify the feasibility of the detection system,an actual test platform was built,and PLA filaments(standard diameter 1.75 mm)were selected for the experiment.The results showed that the detection system could significantly improve the printing quality,and the overall cost was low.
In the vehicle Electronic Stability Control System(ESC),the control of high-speed on/off valve is generally used to achieve pressure control of the brake wheel cylinders.The composition and principle of ESC hydraulic system was analyzed,the physical structure of the high-speed on/off valve was analyzed and its mathematical model was established.Based on this model,a simulation model of the high-speed on/off valve and ESC hydraulic system was established by the AMESim simulation platform.Simulation of dynamic response characteristics of high-speed on/off valve models using high-frequency PWM technology enabled ESC to control the wheel cylinder pressure.The effect of duty ratio on the electromagnetic force,spool displacement and wheel cylinder pressure in the high-speed on/off valve was analyzed in depth through simulation.The results showed that the high-speed on/off valve simulation model constructed could realize active building up,holding or reducing the ESC brake pressure.Precise control of wheel cylinder pressure was achieved by controlling the PWM duty ratio,and the error of maximum pressure compared with experiment was controlled within 5%.
Taking the high-voltage wire as the research object,the current carrying capacity and starting condition of the high-voltage conductor were verified and simulated.A Saber-based simulation test method for the load capacity of electric vehicle high-voltage wire in different temperature fields was proposed.The thermal resistance of conductor layer,thermal resistance of insulator layer and the size of temperature field were added by using MAST language,and the current carrying model of high voltage wire based on temperature field was established.Saber technology was introduced to simulate the current carrying capacity and start-up condition.The verification test was carried out by setting up LabVIEW test platform.The results showed that the accuracy of the simulation results of the current carrying capacity of the wire was 93.11%,and the accuracy was optimized by 28.85%compared with the traditional analytical method.
With the development of driverless driving,the scale of data generated within the automobile system is already very large.The most widely used CAN bus in the vehicle network may not meet the demand in the future,while FC-AE-1553(1553 for short)bus supports optical fiber transmission,with high transmission speed and reliability,and is widely used in the military field.In order to apply 1553 bus to vehicle network,a bus communication module based on APSoC platform was designed by combining real-time operating system.Through simulation and test,the module supports CAN communication and 1553 communication,and supports bus conversion,meeting the design requirements.
As one of the key research fields of intelligent driving vehicle,motion control can not satisfy the requirements of changeable road conditions by longitudinal control and lateral control alone,therefore,it is necessary to design a comprehensive control strategy under the premise of considering the vehicle driving stability.This paper proposes an intelligent vehicle yaw stability control strategy that integrates the LSTM network and fuzzy control.The nonlinear mapping relationship between vehicle parameters was completed by training the LSTM so that the predicted state output was as close to the actual value as possible.To ensure the real-time performance of the control system,the LSTM network was used to predict the state of the vehicle at the next moment through the known state of the vehicle,and the predicted state was used to estimate the stability of the vehicle.When the vehicle was unstable,an optimization constraint was constructed with the center of mass slip angle and yaw rate,and an adaptive strategy based on fuzzy rules was used to convert the estimated state error of the vehicle into a control variable.It was verified by simulation experiments that the proposed control strategy could ensure the accuracy of path tracking and improve the stability of the vehicle under complex working conditions.
This paper proposes a new method for extracting the skeleton of 3D models for the problems related to difficult processing or high processing cost that will be encountered in the process of structural reconstruction.The skeleton could describe the original solid structure and provide the basis for data reuse and parametric reconstruction of the structure.The extracted skeleton contains not only the geometric topology and spatial topographic features of the structure,but also the physical characteristics of the structure.During the extraction process,the 3D model was divided into several blocks,and the coordinates of the midpoints of these blocks were calculated.The grid nodes closest to the midpoints were used as key nodes,and the relative positions and distances of these key nodes were calculated.The skeleton of the structure was formed by connecting key nodes according to the adjacent relationship.APDL code was programmed to extract and save the physical properties of these key nodes.The method was illustrated by using a numerical example through ANSYS Workbench.This example proved that the skeleton extraction method could extract each key node in the structure,and after connecting each key node,the skeleton inside the structure could be obtained to reflect its geometric features.And physical characteristics such as stiffness matrix and deformation coordinates could be obtained from the skeleton,so as to realize the representation and storage of data-based structural features.
The CRH3C high-speed train was taken as the research object,and with reference to its actual design parameters and structural characteristics,the car body model with 14 degrees of freedom as a whole was built using ADAMS software.The safety evaluation indexes such as wheel/rail vertical force,lateral force and overturning coefficient were used to comprehensively analyze and verify the safety of train operation in combination with dynamic simulation data;Finally,the program was innovatively edited through LabVIEW software to calculate and check the vehicle's ability to pass through multiple types of curves such as double"S"curves,and a unique algorithm for vehicle passing through curves was obtained,which could be applied to the theoretical calculation of high-speed train passing through curves of any type.It provides data reference and theoretical basis for future research in this area.
Through the analysis of the application environment of the equipment,a set of multidirectional constrained wire mesh vibration isolation device with buffer function was designed,which was arranged with tension and compression isolators on the upper and lower mounting surfaces respectively and buffer on the left and right sides.The dynamic and response spectrum analysis was carried out to determine the frequency design range of the vibration isolation device,and the required stiffness of the vibration isolation device was calculated.The static test and sinusoidal frequency sweep test were carried out on the vibration isolator and buffer,and the accuracy of the design was verified through the test.
To improve the lubrication performance of truck axle bearings,an isotherm contact elastic-fluid dynamic pressure lubrication model considering surface roughness was established under heavy load conditions.The finite difference method was used to solve the model,and the influence of the variation of parameters such as equivalent radius,lubricating oil viscosity,roughness amplitude and roughness wavelength on the lubrication characteristics was analyzed.The results showed that the oil film pressure decreased and the oil film thickness increased with the increase of the equivalent radius within the variation range of the studied parameters.With the increase of lubricating oil viscosity,the maximum pressure increased first and then decreased,and the minimum film thickness increased gradually.With the increase of roughness wavelength,the maximum pressure decreased first and then increased,the friction coefficient decreased first and then increased,and the minimum film thickness changed little.With the increase of roughness amplitude,the maximum pressure decreased first and then increased,the friction coefficient increased gradually,and the minimum film thickness changed little.When the equivalent radius was increased within a reasonable range,the lubricating oil viscosity was 0.11～0.345 Pa·s,the roughness wavelength was 1.2～1.54,and the amplitude was less than 0.02,the lubrication performance was the best,and the fatigue life of bearings was improved.
Due to the increase in the requirement of automobile lightweight,aluminum alloys are more and more widely used in the automotive industry,and the repair of defects and the improvement of mechanical properties of aluminum alloys have become the focus of research.The effects of pulsed current treatment on the tensile strength and elongation of 6061-T6 aluminum alloy specimens were investigated by tensile experiments,and the changes of current intensity and stress near the defects were studied by coupled thermal-electrical analysis with the help of finite element simulation software.The results showed that the pulse current treatment could improve the tensile strength and elongation of 6061-T6 aluminum alloy specimens and enhance their mechanical properties.The results of coupled thermal-electrical analysis showed that the intensity and stress magnitude of the current near the defects of different shapes of voids at different locations were different,indicating that the healing effect of different shapes of defects at different locations was different.
An improved YOLOv4 mobile robot environment awareness method was proposed to address the problems of occlusion and blurring of images and low detection accuracy and slow detection speed in the case of complex backgrounds in mobile robot obstacle detection.Firstly,the YOLOv4 backbone feature extraction network was replaced with a Ghostnet lightweight network structure,and the computational cost of the network was reduced.Secondly,a spatially separable residual fusion structure was added to the feature extraction network to improve the accuracy of target detection.Finally the obstacle detection algorithm was validated on a mobile robot.The experimental results showed that the mAP of the improved model reached 91.7%,the frame rate was up to 40.1 FPS,the weight size was reduced by 70%,and the model had a better detection effect on multiple targets,overlapping targets and fuzzy targets,which met the real-time and accuracy requirements of the mobile robot obstacle detection.
A certain SUV had a problem of large steering wheel vibration during acceleration process,which was specifically reflected in the experience of hand numbness caused by steering wheel vibration at about 80 km/h;the NVH user experience of the whole vehicle was seriously affected.The 130 Hz local mode of the drive train was confirmed to be the real cause of the problem through the objective test and subjective evaluation,the modal identification of parts under the condition of the whole vehicle.It was effectively concluded that high frequency vibration of steering wheel above 100 Hz could be perceived by human body,and it was verified that the front drive axle housing vibration absorber could effectively reduce the vibration amplitude of the steering wheel under the problematic frequency;the performance of the steering wheel vibration quality under acceleration conditions was improved.The electromagnetic vibration test station was innovatively applied to simulate the steering wheel vibration problem of a real vehicle,the corresponding results of the objective value and subjective score under different vibration frequencies of the steering wheel were summarized,and the rapid evaluation of the steering wheel vibration problem level was realized,to provide reference for solving the steering wheel vibration problem.
