Structural Design And Optimization Of Magnetorheological Fluid Torsional Vibration Damper

Torsional vibration of crankshaft system is an important factor affecting the service life of crankshaft parts.Usually,a damped torsional vibration absorber is installed at the free end of engine crankshaft system,such as silicone oil torsional vibration absorber,to reduce its amplitude of torsional vibration and achieve the purpose of shaft vibration reduction.Based on the non-adjustable characteristics of silicone oil torsional vibration damper,a new type of magnetorheological variable damping torsional vibration damper was designed for the torsional vibration characteristics of crankshaft system of a diesel engine.The main contents include:(1)The phenomenon of engine crankshaft system torsional vibration and its reduction and avoidance measures were analyzed and studied theoretically.Based on the crankshaft parameters of a certain type of engine,a centralized parameter model of engine crankshaft system was established to analyze and calculate the torsional vibration characteristics of the crankshaft system,such as its natural frequency and formation.(2)Based on the theoretical analysis of the basic principle and working mode of the rotary magnetorheological damper,a new type of rotary magnetorheological torsional vibration damper with silicone oil was designed,And a dynamic model of the new type of damper was established,then analyzed and solved the controllability,power and other vibration reduction characteristics of it.(3)The simulation model of the designed torsional vibration damper was established,and the electromagnetic simulation analysis was carried out using ANSYS software to study and analyze the influence of the structural parameters of the damper on the magnetic induction intensity of the damping channel.In addition,the genetic algorithm was used to optimize the structural parameters,and finally the structural parameters with the best effect of the magnetorheological vibration damper were selected.(4)The torsional vibration of engine crankshaft with silicon oil damper is analyzed experimentally,and the dynamic simulation results of the designed torsional vibration damper are compared..The results show that the silicon-oil shock absorber can reduce the amplitude of a single order torsional vibration of the crankshaft obviously,while the magnetorheological torsional vibration shock absorber can effectively reduce the amplitude of multiple order torsional vibration of the crankshaft due to its adjustable damping ratio.