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.
