An approach for FEATURE prediction of MOTORCYCLE ENGINE NOISE under combustion load

This paper presents an approach to predict engine noise under combustion forces. The methodology is divided into three stages: 1. Multibody dynamic (MBD) simulation to determine excitation forces 2. Vibration analysis of the engine under combustion load 3. Acoustic analysis of the engine to predict Sound Pressure Levels (SPL).

Important parts of a single-cylinder motorcycle engine are considered flexible components in MBD simulation. It is necessary to accurately model the crankshaft bearing to capture the transmissibility of combustion forces from the crankshaft to engine casings; forces predicted from MBD simulation are applied to the engine FE model for carrying out vibration analysis and predicted vibration response of the engine at select locations is compared with test data. It was found that predicted response was well in agreement with test response. Hence, corrective actions can be implemented based on analysis results in early design stage by carrying out structural modifications.