Rigid-flexible Coupling The Use Of Multi-body Dynamics In The Four-cylinder Cars Use Diesel

The Multibody System Dynamics widely apply in astronautics, the vehicles, the robot and so on in the mechanical system, the multi-rigid dynamics already obtained have applied successfully. Is facing the light quality along with the mechanical system, high speed, large-scale and the complex direction develops, the system running rate speeds up, the movement precision request is more and more high, makes the rigid body supposition the part the multi-rigid body systems dynamics to be unable to explain the system complex dynamics shape, therefore to flexible body part research into general scholar's research key. The crank flexibility sees not much to dynamics response influence in the diesel engine dynamics analysis, this article will attempt just - the supple coupling Multibody System Dynamic method to apply in the diesel engine crank dynamics response and the torsional vibration, the piston rap and two movements.This article take the 4100QB diesel engine as the object of study, theoretically systematically has comprehensively analyzed the diesel engine piston - shafting Multibody System Dynamics response from the polysome dynamics, and establishes the full-scale mockup in the Adams software. In order to enhance the computation the precision, has carried on the finite element analysis to the crank, using modality principle of superposition, causes in the model the crank rigid body to transform as the flexible body, and joins the crank flexible body in dynamics response, calculated the main bearing and the connecting rod bearing stress situation, had proven calculates the result precision using the flexible crank to be higher, can reflect the real situation.Because the crank movement environment and the structure characteristic is extremely complex, therefore must consider the crank flexibility in the research crank torsional vibration process to the torsional vibration influence. Facing fundamental research quite mature torsional vibration, the author has established the Rayleigh model first, Has carried on the torsional vibration computation. And has carried on the crank torsional vibration analysis in Multibody System Dynamics software Adams. Data and empirical datum contrast analysis calculates which both,Obtains theRayleigh law the result which in host, in the strong harmony time calculates and actual tallies well, but other harmony inferior result which calculates with Adams and actual tallies well, therefore must unify two methods in the computation crank torsional vibration analysis the merits to enhance the computed result the precision.Used the testing method to gain the drop-point place spot transport ratio characteristic, and unified the Multibody System Dynamic method analysis to obtain the piston and the cylinder jacket drop-point place equivalent mass, the equivalent stiffness and the equivalent damping, has established the piston rap process dynamics model, overall evaluation cylinder internal combustion gas pressure, connecting rod action, piston and cylinder jacket friction force, carries on the computation and the analysis using the Matlab language to the piston rap strength and the piston two movements, obtains with the diesel engine actual operation operating mode closer piston rap strength. Meanwhile has analyzed the piston bias quantity and the quality using the adams software to the piston rap strength influence.