Methodology Development for Open Station Tractor OEL Noise Assessment in the Virtual Environment 2021-26-0310

There is a higher demand for quieter tractors in the agri-industry, as the continued exposure to noise levels have disastrous effects on operator’s health. To meet the world-wide regulatory norms and to be the global market leader, its mandatory to develop the comfortable tractor which meets homologation requirements and customer expectations.

Typically, Operator Ear Level (OEL) noise has been evaluated in the test, after First Proto has been made. This approach increases cost associated with product development due to late changes of modifications and testing trails causing delay in time-to-market aspect. Hence, there is a need to develop the methodology for Predicting tractor OEL noise in virtual environment and propose changes at early stage of product development.

At first, full vehicle comprising of skid, sheet metals and Intake-exhaust systems modelled has been built using Finite Element (FE) Preprocessor. In this methodology, reverse acoustic modelling approach has been used to characterize the major noise source such as engine, exhaust system and cooling fan using the measured data. Primarily Sound pressure levels (SPL) has been measured around engine using microphone arrays, measured SPL values were mapped to the Engine Surface mesh using Pellicular Analysis method available in FE tool to predict surface vibrations. Exhaust system and Cooling fan represented with monopole sources. SPL values measured at 1-meter distance in the test for Exhaust and Fan and transfer function is used to compute the amplitude of monopole sources.

An exterior acoustic mesh built around the full vehicle model using FE Tool, using reverse computed engine surface vibration, exhaust and cooling fan Source Strength as the excitation source, Acoustic simulation has been carried out in FE Tool to predict operator ear noise level.