The paper presents a reliability-based approach to assess the structural integrality of tubular joints with cracks in aging offshore platforms. Two different fatigue failure models are established respectively according to crack propagation size and equivalent fatigue strength, and the corresponding computing methods of fatigue reliability are proposed. The fatigue stress of tubular joint suffering sea wave load is calculated by spectrum analysis. The numerical examples are given to show the difference between the two reliability models. Considered the influence of inspection and repair, the reliability is updated by two different maintenance schedules. The analysis results can help to work out the optimal inspection planning, so as to prolong the service life for aged offshore platforms.

We propose an infrared thermal image processing framework based on a modified fuzzy c-means clustering algorithm with revised similarity measure in this paper. The framework can realize the defect detection of a metal part with rough surface. Firstly, a comprehensive method is used to preprocess infrared thermal image. Secondly, the preprocessed image is segmented using modified fuzzy c-means clustering algorithm with revised similarity measure. Finally, taking the average gray level of each cluster in the original gray scale image as a feature, defect cluster is recognized. Experimental result shows that the proposed framework has very promising performance and can obtain precise information of defects on a metal part with rough surface.