Development Of Torsional Vibration Test System Of Marine Diesel Engine’s Shafts

The torsional vibration of marine diesel engine is an important factor affecting safe navigation. To avoid engine damage accidents that caused by torsional vibration, diesel engines and shafts should be carried out torsional vibration calculation during the detailed design stage. After the first diesel engine is manufactured, or the completion of the ship, torsional vibration measurements should be timely carried out. The purpose of this paper is to develop a software program to measure and test torsional vibration of marine diesel engine’s shafts.Currently, torsional vibration test instruments can be divided into two kinds by pick-up devices; they are contact measure instruments and non-contact measure instruments. The method of non-contact measurement of torsional vibration usually picked torsional vibration information by measuring the pulse signal of the shaft encoder. Measuring torsional vibration by using digital methods does not require calibration of the signal. Torsional vibration information can be obtained by processing the sample of the signal in the software.In this paper, the generation principle of torsional vibrations were described. The main factors that affect the measurement accuracy of torsional vibration were analyzed and the ways to eliminate the impact were discussed. In this paper the torsional vibration signal extraction and software interpolation methods to improve the accuracy of torsional vibration measurement were analyzed and discussed.Based on the torsional vibration measurement methods, and according to the non-contact measurement principle, this paper developed the software by using LabVIEW. The software including system settings, signal acquisition, signal processing, data analysis and test reports five functional modules. Each functional module independently programmed to achieve the corresponding functions. The main sub programs of the software were verified by using simulated signals. The results showed that the sub programs were fully compliant data processing requirements.