Research Of Impact Response And Torsional Vibration Of Electric Propulsion Shafting

With the rapid development of power electronics technology,electric propulsion has gradually become the mainstream development direction of ship power system in the future.In the actual navigation process,the ship navigation environment is very complex,and the electric propulsion shafting is not only vulnerable to the external impact load,but also the electromagnetic torque of the propulsion motor will have an impact on the torsional vibration of the shafting.The strong vibration will cause the damage of the propulsion shafting and threaten the safe operation of the ship.Therefore,the analysis of vibration characteristics of electric propulsion shafting can not only provide certain theoretical guidance for shafting design,installation and protection,but also meet the needs of the future development of ships.Based on this,this paper takes the electric propulsion shafting as the research object,and calculates the impact resistance and torsional vibration characteristics of the electric propulsion inclined shaft and general electric propulsion shafting under different excitation through the establishment of structural model,formula derivation,numerical simulation and other means.The main work and conclusions are as follows:(1)On the basis of the general electric propulsion shafting,a special transmission mode is introduced to solve the problem of the huge difference between the center line of the main engine and the center line of the shafting.Different calculation models are selected for the shock resistance and torsional vibration characteristics of shafting.Finally,an example is given to verify the accuracy of Newmark method selected in this paper.(2)Torsional vibration analysis was carried out on the double cross universal coupling capable of implementing the key Angle bending drive,and coupling model of the coupling and shafting was established.The calculation results showed that the system was still stable when the included Angle of the axis was changed within the allowed range.(3)Aiming at the impact resistance characteristics of electric propulsion shafting,the form and characteristics of impact load are firstly introduced,and then a simplified model of electric propulsion shafting is established to calculate the displacement response of the motor under impact and the displacement response and impact stress of key nodes on the shafting through numerical simulation.The results show that the bearing rigidity is large,the shafting displacement response is small,and the bearing impact force is large.The impact response of the electric propulsion inclined shaft is greater than that of the general electric propulsion shafting.The dip Angle of the intermediate shaft is within 16°,and the maximum difference of vibration displacement between the electric propulsion inclined shaft and the general electric shaft is within 8.1%.When the dip Angle is 20°,the maximum displacement difference is more than 23%.(4)For torsional vibration,an equivalent model of electric propulsion shafting was established to calculate the torsional response of the shafting under the three working conditions of electromagnetic torque and ice load.The results show that under the same conditions,the ice loading condition 3 produces the largest effect,the motor produces the largest torsion Angle response at 60r/min,and the maximum torsion stress response at40r/min.The torsion response of the electric propulsion oblique shaft is greater than that of the general electric propulsion shaft,the maximum torsion displacement difference is 8.5%,the maximum stress difference is 9%.