Active control analysis of mining vehicle cabin noise using finite element modelling

Abstract

Numerical simulation has been used to predict the reduction of acoustic potential energy in a mobile mining vehicle cabin as a result of active noise control (ANC). Resonance frequencies and mode shapes of both the structural and cavity modes were calculated using a finite element (FE) model. Modal coupling analysis was used to determine the coupled response of the model to an interior acoustic source, and the results were compared to measurements taken inside the cabin. Correlation between the FE model and physical measurements was improved to the extent that the model could be used to predict the effect of ANC in the cabin for different configurations of control sources and error sensors. As expected from previous work, it was found that the acoustic potential energy inside the cabin could be significantly reduced if a control source is placed in close proximity to the primary volume velocity source. However, increasing the number of sensors and/or increasing the number of control sources located remotely from the primary source had little impact on the achievable reduction in the overall acoustic potential energy in the cabin. This supported results obtained in off-line experiments using control source to error sensor transfer function measurements and quadratic optimization theory, where it was found that good reduction at the error sensors was possible inside the mining vehicle cabin but that global control was not feasible using sources remotely located from the primary source.