Identificação dos parâmetros modais de um motor diesel marítimo utilizando técnicas de análise modal operacional

Abstract

Mechanical failures that naturally occur in components (crankshaft, pistons, connecting rods, gears, etc.) of diesel engines, such as noise, fatigue wear and warping, can be amplified by mechanical vibrations resulting from engine operation. These damages can be aggravated when the engine is operating in conditions close to resonance, due to the significant increase in vibration levels. In this work, a marine engine was chosen for which its modal parameters were identified from the vibration signals measured during the stall test. In the analysis, the SSI-COV and LSCE techniques, developed in the time domain, were used. Among the results obtained, 22 natural frequencies were identified between lateral and vertical and 9 torsional frequencies, and only 2 of the frequencies obtained are within the operating range of the motor (up to 35 Hz), the others are above 200 Hz. A possible explanation for these high frequencies is the test bench, installed in terrain with much greater rigidity than the rigidity of the ship's engine room where the engine will be installed.