Identification of Crack Length and Angle at the Center Weld Seam of Offshore Platforms Using a Neural Network Approach

Abstract

The reconstruction algorithm for the probabilistic inspection of damage (RAPID) is aimed at localizing structural damage via the signal difference coefficient (SDC) between the signals of the present and reference conditions. However, tomography is only capable of presenting the approximate location and not the length and angle of defects. Therefore, a new quantitative evaluation method called the multiple back propagation neural network (Multi-BPNN) is proposed in this work. The Multi-BPNN employs SDC values as input variables and outputs the predicted length and angle, with each output node depending on an individual hidden layer. The cracks of different lengths and angles at the center weld seam of offshore platforms are simulated numerically. The SDC values of the simulations and experiments were normalized for each sample to eliminate external interference in the experiments. Then, the normalized simulation data were employed to train the proposed neural network. The results of the simulations and experimental verification indicated that the Multi-BPNN can effectively predict crack length and angle, and has better stability and generalization capacity than the multi-input to multi-output back propagation neural network.

Marine Propulsion System Failures—A Review

“…At this stage, failure analysis (or forensic) engineers must work closely with metallurgists, NDT engineers, engineering designers, FEM experts, mechanical engineers, mathematicians, etc. [55,56].…”

Review of Fatigue Assessment Approaches for Welded Marine Joints and Structures

“…The offshore structures [1,[5][6][7] and oil and gas pipelines [8] are subjected to fatigue loadings, and fatigue cracks can be detected. Figure 4 shows the crack at the weld seam of an offshore platform [9]. The welds are generally a weak point of the structure, due to the presence of possible crack-like defects along with high stress concentration effects and tensile residual stresses caused by the thermal welding process itself, so a fatigue design is required (Figure 3) for the fatigue life prediction of ship welded details [2][3][4].…”

“…The offshore structures [1,[5][6][7] and oil and gas pipelines [8] are subjected to fatigue loadings, and fatigue cracks can be detected. Figure 4 shows the crack at the weld seam of an offshore platform [9]. The offshore infrastructure has extended its application from the oil and gas industry to the emerging offshore wind industry.…”

“…The offshore structures [1,[5][6][7] and oil and gas pipelines [8] are subjected to fatigue loadings, and fatigue cracks can be detected. Figure 4 shows the crack at the weld seam of an offshore platform [9]. (SAW), Gas Metal Arc Welding (GMAW), Electrogas arc welding (EGW), Hybrid laserarc welding (HLAW), double sided and one sided, automatic, portable welder, line welder, semiautomatic, and robotic.…”

Plasticity of Bead-on-Plate Welds Made with the Use of Stored Flux-Cored Wires for Offshore Applications

“…These harmful loads include the influence of wind and water: waves, ocean currents, and even atmospheric precipitation [ 4 , 5 , 6 ]. In difficult marine conditions, in addition to mechanical static loads, material fatigue and environmental destruction mechanisms play a decisive role in assessing structural durability [ 7 , 8 ]. According to the “DNV-RP-C201 Recommended Practice—Environmental Conditions and Environmental Loads” standard [ 9 ], environmental conditions affect design and technological decisions on which the life of the structure depends.…”