Identifying the relationship between suspension parameters of underframe equipment and carbody modal frequency

As a critical component of the railway vehicle, underframe equipment has a great influence on the ride comfort of railway vehicles due to their big mass and active vibration. Therefore, study on the relationship between suspension parameters of underframe equipment and the modal frequency of carbody is extremely crucial for con trolling the ride quality of railway vehicles. In this paper, a finite element model of the carbody was developed to investigate the effects of the suspension location, the mass of the suspension equipment, and the suspension frequency on the mode of the carbody. Then, the matching relationship between the suspension parameters and the modal frequency of the carbody was studied through the transfer function. In addition, roller rig tests were performed to verify the numerical simulation model of the carbody. The results show that the suspension parameters of the underframe equipment have a great influence on the mode of the carbody, especially for the frequency of the first bending mode. To improve the frequency of carbody highfrequency bending and reduce energy transfer, equipment with a large mass should be suspended toward the middle of the carbody. The weight of the equipment strongly affects the first bending frequency and energy transfer of the carbody. The frequency of heavy suspended equipment should be sufficiently low to increase the transmissibility of high frequencies and improve the vibration characteristics of the carbody. Although the bending frequency of the carbody can be improved effec tively by increasing the suspension stiffness of thesuspension equipment, in order to reduce carbody vibration effectively, the suspension frequency of the equipment should be slightly lower than the carbody bending frequency.

Mechanical performance analysis and stiffness test of a new type of suspension bridge

A new type of suspension bridge is proposed based on the gravity stiffness principle.Compared with a conventional suspension bridge,the proposed bridge adds rigid webs and cross braces.The rigid webs connect the main cable and main girder to form a truss that can improve the bending stiffness of the bridge.The cross braces connect the main cables to form a closed space truss structure that can improve the torsional stiffness of the bridge.The rigid webs and cross braces are installed after the construction of a conventional suspension bridge is completed to resist different loads with different structural forms.A new type of railway suspension bridge with a span of 340 m and a highway suspension bridge with a span of 1020 m were designed and analysed using the finite element method.The stress,deflection of the girders,unbalanced forces of the main towers,and natural frequencies were compared with those of conventional suspension bridges.A stiffness test was carried out on the new type of suspension bridge with a small span,and the results were compared with those for a conventional bridge.The results showed that the new suspension bridge had a better performance than the conventional suspension bridge.