Research On Several Key Technologies In Vehicle Vibration And Noise Reduction

The vibration and noise of vehicle have not only affected the comfort of drivers andpassengers, but also been the main factors which influence the environment and reliabilityof mechanics. There are many noise sources which have different generating mechanismincluding vibration. Many aspects must be taken into consideration in the identificationand control of noise effectively, which request the researchers to master a variety oftechniques including different kinds of source identification methods, modern signalprocessing, modal analysis, analysis and improvement of intake and exhaust muffler, andso on. Therefore, researchers continue to explore how to use these methods flexibly, whichhas important meaning in improving the comfort of vehicle.Taking a certain type of motor tricycle as the research object, an integrated use ofnoise source identification methods which includes signal processing, blind sourceseparation, muffler performance analysis, and modal analysis method are used to identifynoise sources of the motor tricycle. Then, some noise reduction measures are raised andverified by experiment. At last, dynamic characteristics of leaf springs that have a greatinfluence on the vibration of vehicle are analyzed. The main contents of the study aresummarized as follows:(1) The noise spectral characteristics of the vehicle are extracted by using variousmethods. By making an integrated use of traditional methods of noise source identification,signal processing of noise source identification and modern methods of noise sourceidentification-blind source separation, the main noise source of the motor tricycle arefound. In the course of the study, the spectral characteristics of the noise source areidentified and extracted. By analyze the energy distribution of the noise spectrum ofvehicle acceleration and traditional source based on the sound power and arraymeasurements, the main noise source is identifieded. The improvement program of theacoustic pieces preliminarily is proposed.(2) The original car exhaust system are analyzed and studied. Take the exhaust noiseas the largest noise source. By using other methods based on finite element analysis thestructure performance of acoustic performance and aerodynamic performance of theoriginal exhaust system is studed. The original exhaust muffler has been optimized andimproved from the structure, acoustics and fluid, then design a new exhaust muffler. Through the engine bench test, the improved measures of the muffler and designed mufflerare verified. The vehicle’s exhaust muffler is determine(3) of The motorcycle noise source is reducted and verified. Vehicle noise reductionmeasures have been tested and verified from sound-absorbing material and exhaust mufflerthese two aspects based on the first stage of the study. The sound pressure level and soundpressure spectral characteristics of vehicle acceleration of the vehicle whether hasimproved or not has been compared.(4)Statistical energy analysis has been worked on the board structure under therelevant incentive. In two related input model, by establish multi-related input model, theenergy distribution of the conservative and non-conservative coupling structure under themulti-related input and establish an energy balanced equation of complex couplingstructure under the multi-related excitation are sdutied.(5)On the basis of statistical energy analysis of the board structure, to the stiffness ofleaf spring of gradient stiffness, a curvature-load hybrid method is proposed. To thecommon curvature law and the concentrated load method, when calculate the leaf springof gradient stiffness whose vice-spring is variable cross-section spring, the adaptation isnot good and the precision is poor. A mechanical model of general application of the leafspring of gradient stiffness is builded. Compare the example calculations and theexperimental value of a certain type of Suzuki car’s leaf spring of gradient stiffness, itshows the text proposed the curvature-load hybrid method is simple and has goodaccuracy.In summary, in this study we studied the noise source identification and noise controland leaf spring system which is very important to vehicle vibration comfort.Comprehensive analysis method can effectively identify and control vehicle noise, whilethe curvature-loads mixed method of analysis was put forward to study the leaf springsystem. The method is simple and has good accuracy and the results of has importanttheoretical significance and value to vehicle noise and vibration control in engineering.