| As the high-speed chain drive technology continues to develop, and the car engine needs more reliability, the chain drive systems are used more often in the car industry. The silent chain has many advantages, such as a compact size, the low noise, high wear ability, high reliability and power transmission, so in recent years, it is widely used in the timing drive systems, pump drive systems and balancing draft drive systems in the car engine. Because the silent chain has a special structure and mesh mechanism, it has the important theoretical significance and academic value to analyse the dynamic connect characteristics of the silent chain which is driving.This paper has inspected and analysed many literature about the dynamic characteristic analysis of the chain drive, rigid multi-body, flexible multi-body and contact dynamics. Based on this, and combined with the National Natural Science Foundation of China "Mesh theory and Research methods of New high-speed silent chain", the paper has a deep research of the dynamic contact characteristics of the round pin silent chain by using the rigid and the flexible multi-body dynamics.Firstly, based on the rational literature, the paper analyzes the development status and the future trends of the chain drive and the research of the multi-body dynamics in the world.; According to the relevant figures and tables, the paper introduces the current standard of the chain drive industry and kinematic characteristics of the chain drive; It also builds the kinematic equation of the pins and explains the mechanism of polygon effect according to the velocity change in the chain drive; The paper builds the 3D models of the chain plate and the pin in the timing chain systems of the car engine and has a flexible and rigid multi-body dynamic analysis of them by using the 3D modeling software CATIA and the multi-body dynamic analysis software RecurDyn based on the theory and iterative algorithm of the multi-body dynamics. By analyzing the surface morphology of the chain plate and the pin, the paper compares them with the stress clouds and the force curves from the simulation in the same location, obtain the desired results.The paper introduces the multi-body dynamics analysis process, firstly, builds the 3D models of the silent chain plate and the pin by using the 3D modeling software CATIA, then analyses the meshing process of the chain plate and the sprocket by using the multi-body dynamic software RecurDyn after building the simulation boundary conditions by considering the gap between the pin and the chain plate and the actual working situation of the chain drive. The pin and the silent chain plate have been flexible in the simulation, and the paper analyses the stress change regular, according to the experiment data, obtains the following conclusions:1. The push stress in the contact location between the pin and the chain plate and the contact location between the plate and sprocket is the maximum, and the fatigue wear often appears in these locations.2. The outer mesh chain plate has a larger impact from the sprocket tooth surface then the inner-outer mesh chain plate when they are meshing with the sprocket.3. The paper obtains the wear morphology between the pin and the plate by using the JSM-5310 scanning election microscope, and this is also a support for the former two conclusions.It is an innovation for this paper that analyzing the dynamic contact stress of the pin and the plate based on the flexible and rigid mixed dynamics. It provides a new method to study the meshing stress of the silent chains; It also provides a reference for designing the new silent chains. At the same times, the wear micro-analysis result of the pin and the plate also confirms that the flexible and rigid multi-body dynamic models which are built in this paper are scientific and practical. In summary, the research content and result of this paper has important academic value and engineering significance.
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