Research On The Structural Damage Detection Method Of Offshore Platform Based On Vibration

Offshore platform is the key equipment in the exploitation of ocean oil and gas resources, long-term service in the harsh marine environment, legs are the main load-bearing components,prone to corrosion, cracks and other damage. It may lead to platform overturning accidents when seriously, resulting in huge economic losses and casualties. Therefore, more and more domestic and foreign scholars have carried out offshore platform structural damage detection method research. Among them, vibration detection method can directly reflect the structural health state of structure dynamic characteristics, and has become a hot research topic in offshore platform structure damage detection method.Based on the damage detection method and guided wave technology research status, aiming at the problems existing in the current detection methods, taking the model of offshore platform as the research object, the paper carried out based on the detection of the global modal parameters and guidelines local damage detection method detection wave technologies combined. Details as follows:Firstly, using ABAQUS finite element software, established without injury, solid damage of pile frame and different corrosion damage of jack up drilling platform finite element model, by its dynamics analysis to calculate the modal frequencies and shapes of mode structure of each injury status, simulation results show that, when structural damage, modal frequency is reduced, and the modal shape of damaged area becomes larger shift. Vibration test and analysis of laboratory models and prototypes of the platform verify the validity of the method.Secondly, damaged area is located based on the global modal parameters detection methods for the preceding, combined with offshore platform structure characteristics, using guided wave technology tested local damage. First, the paper carries out the theoretical analysis on the propagation characteristics of the guided waves in cylindrical shell, and then using ABAQUS finite element analysis software carries out simulation of damage detection based on guide wave technology of different levels of damage to Circumferential crack, axial cracks, diagonal cracks and corrosion in the splash zone atmosphere cylindrical shell leg, the results show that the waveguide can accurately detect locations of the leg circumferential cracks, corrosion, and the accuracy with increasing degree of damage increases, diagonal crack detection accuracy of the second, axial crack detection is not ideal. The paper also studied the influence of the subsidiary structure of leg guided wave testing, provided guidance for the on-site guided wave testing.