Analysis On The Crank-train Modal And Torsional Vibration For 1.5T Gasoline Engine

The crank-train is one of the most important components of engine, ensure the reliable of the crank train must be considered in the engine design process. Because the crankshaft suffers periodic force and torque, it is easy to produce torsional vibration of the crank. The torsional vibration would have a strong impact on the engine. It maybe lead to the increase of the noise, engine work deterioration and the serious vibration even destroys the crank. So, it must consider the torsional vibration of the crank train in the engine design process. With a 1.5T four-cylinder gasoline engine in a company as the research object, the thesis does a modal analysis about crank shaft and torsional vibration test, trying to know the characteristics of the torsional vibration of the engine and analysis and compare their three matches TVD torsional vibration.Through the comprehensive use of Pro/E,HyperMesh and Ansys software, the thesis do some finite element modal analysis on crank train. Create a series of three-dimensional solid using the modeling software of Pro/E. Because the crankshaft structure is complex, it has been simplified and removed some small features. This can reduce the workload in HyperMesh software. Hypermesh software can directly mesh the three-dimensional solid with hexahedron and tetrahedron then define cell properties and materials. Ansys with imported results calculates and analysis free modal to get natural frequency and formation of crank train. This thesis focuses on the torsional vibration test of the engine. The test , using LMS vibration noise measurement equipment, completed six times measurement about the speed tracking and fixed speed, aiming at three vibration system. Through experimental analysis, the second and fourth order cause larger torsional vibration . The second order is in the leading position and has bigger amplitude. Vibrations caused by the Second order decrease with rotate speed increasing. The fourth order exists maximum in told areas. The third way has better damping effect in three kinds of vibration reduction plan. It can reduce the vibration caused by each orders and have a more obvious effect for the fourth order.This thesis bases on the research with enterprise cooperation project and takes test as the main contents in order to understand the engine torsional vibration characteristics and select the best vibration system in three existing schemes. This thesis discusses the basic knowledge of Engine torsional vibration, the torsional vibration test principle of the measurement and analysis and the test of the entire process. It has a certain practical value.