Dynamics Of Actual Mechanism In Reciprocating Engine Based On Virtual Prototyping Technology

Impact, vibration and noise can occur for the existence of clearances in kinematic pairsand component elasticity in actual mechanism and machine. They have great effects on thedynamic property and reliability of high-speed and high-precision mechanism. In this thesis,virtual prototyping technology is applied to study actual dynamics of the crank-slidermechanism in reciprocating engine considering joint clearance and component elasticity.First of all, geometry model is built in CAD software Pro/E. Based on the geometrymodel multi-rigid-body model is developed in ADAMS considering the clearance betweencylinder and piston. The Impact Pair Model is used to simulate the contact and impactphenomena between pair element. Dynamic responses of this machine are obtained and effectsof some parameters as clearance magnitude and velocity are also studied. The recommendmagnitude of clearance is obtained by numerical simulation. It agrees well with the practice.Secondly, by using seamless connection settings the geometric CAD model is directlyimported to ANSYS working environment. Modal analysis of connecting rod and crankshaft iscarried out by the finite element software ANSYS. The lower natural frequency and thecorresponding vibration mode of the components are given.Finally, flexible dynamics simulation of reciprocating engine is carried out by combiningADAMS and ANSYS. The flexible models of components are imported to ADAMS in theform of MNF. The multi-body models take the rigid-flexible coupling between the large scalemotion and small scale elastic deformation into consideration. The clearance between pistonand cylinder is also involved in motion equations. Compared with analysis of rigid system, thesimulation results show the existence of motion deviation, and slap intensity of piston isreduced.