Análisis vibracional en ejes de propulsión marina para la detección temprana de fisuras transversales.

Abstract

This project consisted in the experimental and numerical vibrational analysis of a marine propulsion shaft model to study the variations in natural frequencies as a function of the area affected by a crack. The analysis was performed with shafts of 1000 mm length and 17 mm diameter in order to represent a propulsion system belonging to a fishing vessel, in addition, the crack caliber is 0.18 mm. Numerical results were obtained by implementing finite elements, and experimentally they were achieved using accelerometers and impact hammer. Experimental and numerical results indicated a variation of less than 3% up to the second natural frequency. The influence of the cracks in the shaft causes the natural frequencies to decrease, reaching up to a 6% change in the second mode of vibration with the shaft at 60% of the affected area. Also, the shape of the shaft is influenced by the presence of the crack, increasing its amplitude. In conclusion, the numerical results were validated with the experimental ones showing that a crack, located in the joint between the liner and the shaft, can be identified in an acceptable way from 40% of the compromised section. Translated with DeepL.com (free version) Keywords: Cracking, natural frequencies, vibration modes, impact hammer