Abstract. The type and working principle of multi-engine multi-gearbox gearing are introduced. The global dynamic modeling method, based on the generalized finite element theory, and the layered dynamic modeling method, based on the idea of whole first and then partial are proposed, and the dynamic models of three operation modes in the four engines with two shafts are established. The effects of coupling, rotation speed, configuration and power loss on the dynamic response of the system are studied by using the dynamic model. The research results show that the coupling vibration of multi-engine multi-gearbox gearing is obvious at low speed, and the coupling vibration weakens with the increase in speed. Reducing the coupling stiffness can weaken the coupling vibration of the system. The symmetrical structure of the transmission system has the same dynamic response at the symmetrical position. Meshing friction has little effect on the dynamic response of the system. The more power flowing through the cross-connect gearbox, the greater the system power loss. This research provides theoretical support for the low-vibration design of multi-engine multi-gearbox marine gearing and has a positive significance for understanding the coupled vibration characteristics of complex gear systems.
The vibration level is the key index to measure the performance of marine gear transmission device. The compound gear transmission system, which is composed of a helical gear pair and a spur star gear train, is widely used in marine gear transmission device. This paper presents a multi-node dynamic model for a marine compound gear transmission system, investigating the modal properties and dynamic responses of the system. The mesh stiffness and transmission error for each gear pair are determined using the loaded tooth contact analysis (LTCA) model. The theoretical and experimental vibration acceleration responses of the gearbox housing are contrastively analysed. The results show that some vibration modes are very similar to those of a single planetary gear train, but other modes are multi-node and multi-degree of freedom coupling modes. The vibration coupling and transferring phenomenon between two stages can be observed remarkably, but those show obvious differences under different working conditions. The torsional stiffness of the elastic connecting shaft has significant influence on the vibration coupling and transferring phenomenon. The results can provide useful guidance for the low vibration and noise design of the marine compound gear transmission system.
Abstract. This paper designed the Pin-axis Resistance sensor based on the principle of Magnetostriction. The mathematic model of the sensor was established and simulated in Matlab / Simulink. In this paper , load experiment results of resistance sensor showed that resistance sensor's linearity decision coefficient of the static characteristic curve was 0.9965.The output voltage was 0.55V when the shearing force was 70kN.
Reducing the radiated noise of a gearbox is a difficult problem in aviation, navigation, machinery, and other fields. Structural improvement is the main means of noise reduction for a gearbox, and it is realized primarily through contribution analysis and structure optimization. However, these approaches have certain limitations. In this study, a low-noise design method for a gearbox that combines the two approaches is proposed, and experimental verification is performed. First, a finite element/boundary element model is established using a single-stage herringbone gearbox. Considering the vibration excitation of the gear system, the radiation noise of a single-stage gearbox is predicted based on the modal acoustic transfer vector (MATV) method. Subsequently, the maximum field point of the radiated noise is determined, and the acoustic transfer vector (ATV) analysis and modal acoustic contribution (MAC) analysis are conducted to determine the region that contributes significantly to the radiated noise of the field point. The optimization region is selected through the panel acoustic contribution (PAC) analysis. Next, to reduce the normal speed in the optimization region, topology optimization is performed. According to the topology optimization results, four different noise reduction structures are added to the gearbox, and the low-noise optimization models are established respectively. Finally, by measuring the radiated noise of the gearbox before and after optimization under a given working condition, the validity of the radiated noise prediction method and the low-noise optimization design method are verified by comparing the simulation and experimental data. A comparison of the four optimization models proves that the noise reduction effect can be achieved only by adding a noise reduction structure to the center of the density nephogram.
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