MULTISIDED SYSTEM DYNAMIC ANALYSIS OF THE CRANKSHAFT VIBRATION RESPONSE IN I. C. ENGINES
QIN Wen jie (School of Vehicle and Transportation Engineering, Beijing Institute of Technology, Beijing 100081, China)
This paper intends to present a thorough vibration analysis of the crankshaft system in the combustion engine in hoping to improve its working safety and reliability. As the result of our investigation on the basis of the application of elastic wave theory and discrete system analysis it has also proved that the method of calculating the crankshaft vibration response by using the multisided system dynamics is practical and technically favorable. The method helps to join the model of the whole system including crankshafts and the rotating parts, such as pistons, connecting rods and the other factors concerned together, and calculate the interaction between parts directly. Modeling crankshafts as flexible bodies as is done by using our method has also enabled us to take into account their deformation, the vibration response included. The present paper has also made a detailed discussion on how to build up the so called multisided system dynamics model and how to simulate the crankshaft system by integrating the CAD, FEA and MSS technologies in a comprehensive way. The mass properties and geometry of rigid bodies can be derived from CAD modeling. The description of flexible bodies can be generated through finite element modeling and modal analysis. Thus, the whole model can be established by putting all the parts concerned together while considering various constraints involved with its dynamic performance simulated dynamically after applying the external forces. As a practical example, a vehicle's crankshaft system model is provided with its vibration response parameters illustrated.