Dynamic Characteristics And Test Analysis Of The Torsional Vibration Of Diesel Engine Shaft System At Engineering Vehicle

With the rapid development of construction machinery and equipments in China,the scale of the construction machinery and equipment industry comes into being and the engineering level becomes more and more high. At the same time, the require of the modern comfort, safety and lower noise also becomes more and more high, for the scale of the earthwork construction in the city and the water conservancy construction become more and more large. The failures of the axles system of construction machinery and equipment are the problems of the lower performance and noise intensification. The broken of the flywheel in a bulldozer caused crack of the vehicle and death of people, for the oversize of the tornsional vibration amplitude or illogicality of design and manufacture of shafting components. The study of shafting is able to improve the level of dynamic designing of diesel engine and driving system at engineering vehicle, satisfy the demand of the modern comfort, safety and lower noise, and decrease the probability of failure. In the traditional shafting design, the first is concept design and project feasibility demonstration, then product design. As a rule, the model machine made to check out the design is tested. If bug is found in the test, model machine is redesigned and then is tested again. After circles of design, model test and redesign, the shafting performance meets the demand. In the process, the vigor of designer is concentrated on details, not the performance of the whole system. And the cost of model machines is high, and the circle of design is not able to be shortened. By use of virtual prototyping technology, design sequence is reversed. The design process starts from the whole system, then to design the parts. In this way of building a virtual model, the high cost of the system design failure is avoided, the time is far too less than to build a model machine and the virtual model is easy to modify and optimize. By virtual prototyping technology, the optimum project is obtained through compare of all kinds of design projects. Equivalent mechanics models and virtual models are established on the simplification of the sophisticated machinery, and the theory and analysis of torsional vibration of diesel engine shaft system is based on the models established, so the distinction exists between the models and practical systems. The factors that brought distinction includes the simplification of regularities of parameters distribution, degree condensation of freedom, negligence of minor factor, undeterminable or undefined factor and boundary condition. The purpose of study and improvement of kinetic property is that mathematical model is able to simulates the original system and that the models system is able to act as the original. Test analysis is used to validate theory analysis and makes up the distinction between the theory and practical systems, so test is an indispensable method in the study and estimation of shafting vibration. By means of the theoretical calculation, computer simulation and test analysis, we analyzed the dynamic characteristics of diesel shafting at construction machinery and equipments. According to principles of mechanics equivalent system, the mechanics equivalent model is established of diesel shafting at construction machinery and equipments. The vibration exciting force is determined by indicator diagrams and empirical formulas. Based on the mechanics equivalent model, we calculated and analyzed forced vibration of two different operating models with clutch and without clutch. In the third chapter, the finite element modal analysis of three-dimensional entity and the harmonious analytical theories are introduced. We set up the mold of parts of shafting system, discussed the influence of the dynamic characteristics and inherent property with rigid supports or elastic support. According to the ADAMS dynamic theories and method of Craig-Bamptons, making use of the powerful three dimensional modeling of the PRO/ E and mold analysis function of ANSYS, we simulated the dynamic systems of the engineering vehicle diesel crankshaft system, providing the forerunner's analytical technique for the improvement of the power driving system and for controlling the noise. We tested and got the values of torsional angles at different running conditions, so we acquired the torsional vibration curves at different conditions. We got the conclusions mentioned below. â‘ the regulations of torsional vibration are basic homology at different running conditions. We found the main vibro-wave and torsional angles of harmonics fewer than 12 are very small. So, the vibration exciting force selects the first 12 harmonics. When simulated in ADAMS, the finite element model of crank shaft is established in...