Measurement of the three-dimensional exciting force from vibration sources for machinery

To predict ship's structural vibration and noise, it is essential to measure the exciting forces transferred to the ship hull from machinery in ships. For resiliently-mounted machines, an indirect measurement approach based on impedances of the isolator as well as a direct measurement approach based on force transducer are discussed. A diesel engine is then taken as a research object, where PCB force transducer is used to get the exciting force transferred from isolator, eliminating the noise effect of PCB force transducer and improving the direct test precision. Experimental results demonstrate that the error of indirect measurement is less than 3 dB, successfully satisfying practical engineering applications, while the indirect measurement can replace the direct measurement of the exciting force.