Inner Noise Control And Optimize Based On Statistical Energy Analysis

The theory of Statistical Energy Analysis is a new breakthrough in the technique of prefiguring the vibro-acoustic environments that was developed at the end of the fifties to sixties in the 20th century when the new technique on aviation and spaceflight speeded up. It's a kind of module analysis method which can evaluate the dynamic characteristic, vibration response level and sound radiation of the complex and resonance assembly structures theoretically through the relation formula about energy flows, then the statistical feature and the acoustic characters in space and time can be obtained. The theory had been used broadly in the areas such as railway transports, building architectures, naval ship and mechanical manufactures. This thesis explains the engineering rule how to establish a vehicle noise analysis system based on the Statistical Energy Analysis theory, the constitution of the sub-systems which are composed of the sound-spaces inner vehicle and the plate-shells outside vehicle, and summarizes how to deal with the coupled relationships between the sub-systems in the software-Auto SEA when the model is erected. The methods used in the sound insulation and sound absorption about the noise control are studied. According to the principle of Equal Sound Penetrate Degree used in the composite structures, the method to find out the weak point in controlling the vehicle inner noise is brought forward, such as calculation of the sound insulation quantities using the software Auto SEA and obtaining of the sound pass-through degree using the software MatLab. The bigger the degree is, the weaker the sub-system is. In order to get a good model that can be used to evaluate the inner vehicle noises, the spot test is carried out, then is applied on the models made already. Using software Auto SEA to calculate the energy flow between the sub-systems and under the Equal Penetration Sound Degree rule, the weak points of vehicle inner noise control are found out. Applying the Experimental Optimization Design method to the weak points of vehicle inner noise control, the orthorhombic experiment design charts are founded and the penetrated sound degree coefficients are calculated. From the results of the charts, the optimal factors are selected and applied to the vehicle model. The noise optimal results sound well. The task that have been accomplished is summarized, the matter that had been done deficiently is expounded, and the work about the vehicle inner noise control, imitation and design based on the Statistical Energy Analysis theory just started in china, there are still much work to be done.