Research On Impact Wave Dynamics Of Vehicle Elastic Component Vibration And Its Application

Vehicle vibration and noise are the two main factors that affecting the level of comfort when vehicle running. With the increasing of vehicle velocity, the impulse force of road unevenness also increases. The vibration energy in high frequency becomes the main energy source that excites vehicle body vibration and radiates noise. So the separate vibration research of suspension system must be developed with higher frequency. The characters of elastic components in vehicle are the main factors that affecting vehicle vibration, when researching the high frequency vibration of vehicle. We must analyze the transmission characters in high frequency of all separate vibration components, as it is the basis of vehicle vibration research. Impact wave theory is applied in this thesis to analyze the high frequency vibration and to discover some phenomena of the high frequency vibration of vehicle. It can promote the control ability technology of vehicle vibration. This thesis regards the vehicle vibration components as the concrete research object, which means orienting the theory research to the real product; it can improve the vehicle design level and competing ability in our country. Based on these viewpoints, the research work in this thesis is carried out as follows:1. Three elastic components wave equations are set up and a new method is put forward to find solution to the transmission character of helical spring. The elastic wave transmission velocity in the helical spring and the transmission characters of displacement, velocity, stress, strain and force of the spring transmission are researched. The solution of elastic single wave of helical spring and problems of wave interference are analyzed. The wave resistance equation of helical spring using straight spar model is developed. It can concludes that the transmission character of helical spring is equal to straight elastic pole, that the wave equation of steel spring is not suitable to high frequency vibration analysis, that it can describe moment inertia, but should pay attention to applying range, because the difference is very large between helical spring and twisting spring.2. The transmission character of helical spring is applied to discuss the solution to the l-Dof system impacted by short wave. The responses and the effect on the response when spring stiffness changed are analyzed and discussed.3. The classical vibration theory and impact wave theory are applied to simulate the helical spring suspension vehicle vibration and its response is analyzed. It puts forward the theoretical support of using the impact wave mechanics to analyze the vehicle vibration, develops the expression equation of the wave resistance of helical spring stress wave and sets up wave resistance force and deformed force vibration models of vehicle, it also sets up helical spring inertia force and deformed force vibration models of vehicle which based on the effect of the impact wave on the helical spring length and corresponding mass, sets up wave theory modeling of vehicle vibration of helical spring suspension by considering many factors, it also discusses the solutions to model and compares all the models in theory and solution. Simulation and test prove consistency of impact wave theory model and classical vibration theory model in low frequencydomain and satisfying the shortcomings of the latter which can not express high frequency vibration. It concludes the application method of helical spring parameters and the simulation method of high frequency response of suspension in wave theory.4. The transmission character of helical spring is applied and 2-Dof vehicle model is setup that impacted by wave according to wave impact theory. The response that impacted by short wave of variational stiffness helical spring suspension is researched. Stimulate vehicle response that impacted by different frequencies under the condition of considering concrete structure of helical spring, discover the reason that high frequency vibration of variational stiffness and its affection analysis.5. Classic vibration theory and impact wave theory are applied to stimulate the vehicle vibration of torsion bar suspension vehicle and helical spring suspension vehicle, transfer the two suspension models to uniform model and transfer the wave resistance force and inertia force of two elastic components to comparable equivalent parameters, analysis the affection of the two parameters on vehicle high frequency vibration. It can provide reference to the variety of stimulation method, suspension design and control vehicle vibration.6. Experimentation research on vibration of vehicle is carried out. Vehicle bridge and elastic components floor vibration are measured, which verify the correctness of wave dynamics and that translating high frequency vibration into impact vibration, and the definition of duration, and the application range of wave equation.