Multi-body Dynamics Simulation Research Of The In-line Four-Cylinder Gasoline Engine Crankshaft System

Crankshaft system is one of the most important mechanisms in engine, and connecting-rod is one of the most important parts of force transmission in engine, it bears complex load which consists of gas pressure in cylinder and inertia force. Besides, because the shape, the boundary condition and the load of the connecting-rod is very complex, it is very important to simulate motion characteristics of connecting-rod in practice. To simulate the behavior of connecting-rod well, a good computational simulation analysis method is very important.Multi-body system dynamics simulation is a effective method in mechanisms simulation of engine, dynamic response of crankshaft system is analyzed well in computer. It will provide very valuable information for the design and optimization of engine. This is the development trend of modern design of engine.In the paper, in-line four-cylinder gasoline engine crankshaft system is taken as the research object, using ADAMS and ANSYS to analyse multi-body dynamics modal of crankshaft system. Firstly, analysing normal modal of connecting-rod to get its natural frequence and mode shape in each order. Theory motion analysis of crankshaft system is carried out by MATLAB and showed by motion curves. Then dynamic of the models are simulated using ADAMS, and simulation results of the rigid bodies dynamics model and the soft bodies dynamics model are compared, and analysing the motion path of the center of mass of connecting-rod to get its change. Lastly, the results in ADAMS are used to achieve transient dynamic analysis of connecting-rod in ANSYS to get its stress distribution and strain distribution and find its dangerous areas, it will be taken as the important reference for the connecting-rod fatigue analysis and optimization.