Torsional Vibration Calculation And Configuration Optimization Of Crankshaft Of Diesel Engine

Due to the long axial length and the reciprocating inertia moment of the piston,the crankshaft of the diesel engine is prone to torsional vibration.Huge vibration may cause failure of transmission instability between components,may affect ride comfort and even cause fatigue failure of shaft segments.So the torsional vibration analysis and configuration optimization of the crankshaft system are needed.The existing torsional vibration calculation software or program is too complicated in optimization,it needs recalculate the response results of new system of modified parameters.Therefore,this paper compiled genetic algorithm optimization program according to the optimization objective,but it spends a long time,the sensitivity analysis method based on the inherent characteristics of the system can quickly guide the optimization direction of parameter.The equivalent lumped parameter model of crankshaft is established according to the modal invariance principle of the system,the accuracy of calculation based on equivalent model parameters.Due to experimental formula can't get accurate torsional stiffness of step shaft and crank,it doesn't consider the influence of fillet of stepped shaft and constraint of main torsion bearing on actual torsion deformation.This paper researches about the dynamic parameters of step shaft and crank through using finite element analysis,and proposes the modifier formula which is more accurate in aspect of calculating the torsional stiffness of step shaft with fillet.The dynamic response of the critical mass point can be calculated quickly by using the mode superposition method.Using Fortran program to calculate the natural vibration and forced vibration response.The result show that the rolling vibration of the system is obvious at low speed,and the torsional vibration is huge at high speed,so the parameter optimization of the damper and structural is needed.According to the principle of single pendulum vibration absorber system of the kinetic parameters of primary damper design,and analyzes the influence of damper dynamic parameters on torsional vibration system.Then use Genetic Algorithm to optimize the damper dynamic parameters and flywheel inertia,torsional vibration of the optimized system significantly reduced;finally using sensitivity analysis method to get the dynamic parameters which has superior influence on the system natural frequency and modes,and optimized the parameters.