Evaluation of sound quality in a tractor driver cabin based on the effect of biodiesel fatty acid composition

Nowadays, one of the main concerns for vehicle customers is comfort. This fact, together with the constraints imposed by legal regulations on noise emissions and human exposure to noise, have led to consider noise and vibration among the most important design criteria for agricultural machinery cabins. In this context, experimental analysis procedures for rapid prototyping and prediction models for early design assessment are crucial. This work presents a study of sound quality inside a tractor cabin mock up when the engine is fueled with different biodiesel/diesel fuel blends. In this study, the influence of the chemical properties of biodiesel has been correlated to sound quality metrics, i.e. loudness and roughness, and thus, their influence on the comfort of the tractor driver cabin. It has been found that cetane number and unsaturation degree of biodiesel are strongly related to loudness, whereas viscosity and unsaturation degree are strong indicators of roughness. Finally, to predict loudness and roughness based on biodiesel chemical properties, surface response models have been developed.