Dual-mass Flywheel Torsional Vibration Analysis And Experimental Study

The structure of automobile power transmission shaft system is very complex, and its power comes from automobile engines which is a source of torsional vibration. The drive shaft is a multi-degree of freedom vibration system and torsional vibration is a main source of vibration and noise, which becomes a direct impact on the quality of modern passenger cars. Dual-mass flywheel is between engine and driving shaft system, so it not only has traditional function of the flywheel, but also can adjust natural characteristics of torsional vibration by changing the mass and rigidity of the Department. Its own damping structure can also reduce the amplitude, so dual-mass flywheel can effectively absorb and attenuation engine vibration and enhance the smoothness of operating shaft system. It has become one of the most effective methods for improving vehicle powertrain torsional vibration characteristics. Further study of automotive power transmission shaft torsional vibration characteristics with dual-mass flywheel can provide theoretical and technical support to improving torsional vibration damping properties of automotive powertrain with dual-mass flywheel. It has great theoretical value and practical significance.The following tasks and innovations have been completed:1. Torsional vibration model of dual-mass flywheel under different stalls has been established. Based on equivalent torsional vibration system theory and combined with structure features of power system with dual-mass flywheel, the finite element analysis method is used for being equivalent conversion to the moment of inertia and torsional stiffness of parts and whole vehicle quality, such as the engine, gearbox, drive shaft, drive bridges, and emphatically for analysing speed control system. The mechanical computing model of automotive driveline torsional vibrations under different stalls is established.2. The free torsional vibration characteristics of dual-mass flywheel shaft are analyzed. The researched object is the shaft of VM25C Diesel passenger vehicles matching LUK1005dual-mass flywheel torsional vibration damper. The free torsional vibration has been analysed and calculated by adopting system matrix method, then natural frequencies and vibration modes have been obtained.3. Forced torsional vibration characteristics of dual-mass flywheel shaft is analyzed. The researched object is the shaft of dual-mass flywheel torsional vibration damper. By analyzing the excitation source of automotive transmission system it is determined that the exciting moment of force generated by gas pressure changes inside the engine and moment of inertia changes of its motion part, and then the shaft torsional vibration under excitation force of the engine is calculated and analysed. The torsional amplitude has been calculated.4. The analysis software for torsional vibration characteristics of automobile transmission shaft system has been developed. It has many functions such as calculation of shaft's natural frequency, and display of vibration mode, calculation of critical speed, etc.5. The test-bed of the shaft with dual-mass flywheel torsional vibration is designed and built. Excitation source is the VM engine, and its power is 105KW in order to simulate the shaft actual torsional vibration characteristics. In order to make the test-bed capable of simulating a variety of models'dynamics characteristic of drive shaft system, inertia wheel group has been designed by analyzing the mass conversion of inertia wheel group, critical speed and dynamic balance. The structure of test-bed has been fixed on after the shaft stiffness of test-bed being modified. The order times value of torsional vibration signal has been obtained through theoretical analysis to torsional vibration node of drive shaft.6. The dual-mass flywheel torsional vibration characteristics is verified by experiment. The experiments include the torsional vibration test under the idling condition and the comparative test of torsional vibration under various operating conditions. Then the test error analysis of torsional vibration test is analyzed. Tests show that the test-bed can simulate various shaft torsional vibration characteristics for vehicle weight 1500KG-2000KG under different conditions that includes different shifts and different speed. The simulation of actual working conditions is realistic, the extraction of measuring torsional vibration signal is stable.