Identification On Cab Noise Source Of Construction Machinery

Noise is the key factor in the quality evaluation of the construction machinery. Noise in the cab is not only related to the comfortable performance of the machinery, but also can provide an important guidance to overall performance. The vibration of vehicle and structures is correlated with the driver’s comfort. It’s more important on the machinery operation and driver’s safety and health. So the noise source identification is of great significance on the noise control in the machinery cab.The paper is written based on school-company cooperation project "noise rectification in the bulldozer cab". Throughout the analysis of the noise causes and characteristics, the paper identifies the air-borne noise and structure-borne noise influence on the ear noise in the cab, so we can propose the reasonable measures to reduce the sound level on the driver’s ear.The paper uses the wavelet packet analysis and support vector machine recognition method to identify the noise source. Using the wavelet packet analysis to calculate the air-borne noise contribution to the ear noise by leaking into the cab through the apertures, first decompose the signal into three layers with wavelet packet to extract the signal feature, then calculate the correlation coefficients to identify the air-borne noise to ear noise contribution. Use a new method of noise source localization-pattern recognition with support vector machine to evaluate the structures in and around the cab how to influence the ear noise. Extract the characteristics with wavelet packet decomposition as vector samples. Construct sub classifiers between each two vehicle structures. Recognize which structures characteristics are more closely to the ear noise. Then identify each structure’s contribution to ear noise. At the same time, the paper implies the correlation coefficients to verify the validity of the new method. Taking the cab’s damping system’s reduction for the vibration energy transferring into the cab into account, set up the correlation coefficient calculation model, identifying the contribution on ear noise.Based on the analysis results, take the insulation and seal measures in the cab to reduce the air-borne noise leaking amount into the cab and optimize the structures to enhance stiffness to improve the construction machinery’s performance. For the damping system, improve the damping system performance by adjusting the stiffness. Verify the effects of typical structures influence on ear noise on the basis of analysis.