Multivariate Analysis to Relate CTOD Values with Material Properties in Steel Welded Joints for the Offshore Wind Power Industry

Abstract

The increasingly mechanical requirements of offshore structures have established the relevance of fracture mechanics-based quality control in welded joints. For this purpose, crack tip opening displacement (CTOD) at a given distance from the crack tip has been considered one of the most suited parameters for modeling and control of crack growth, and it is broadly used at the industrial level. We have modeled, through multivariate analysis techniques, the relationships among CTOD values and other material properties (such as hardness, chemical composition, toughness, and microstructural morphology) in high-thickness offshore steel welded joints. In order to create this model, hundreds of tests were done on 72 real samples, which were welded with a wide range of real industrial parameters. The obtained results were processed and evaluated with different multivariate techniques, and we established the significance of all the chosen explanatory variables and the good predictive capability of the CTOD tests within the limits of the experimental variation. By establishing the use of this model, significant savings can be achieved in the manufacturing of wind generators, as CTOD tests are more expensive and complex than the proposed alternatives. Additionally, this model allows for some technical conclusions.

Material Behavior and Fatigue Assessment of Old Steel Bridges of the Spanish Conventional Rail Network

“…Mechanical resistance: Mechanical resistance plays a fundamental role in and forms a constitutive part of fracture mechanics [26]. Additionally, the determination and control of its value is a fundamental part of the quality control of the material properties (for structural materials).…”

A Methodology Based on Magnetic Susceptibility to Characterize Copper Mine Tailings

“…MARS was calculated by using the earth [69] library of the statistical package R [70], while the other statistical calculations were made with Minitab. Using data from Tables 3-5, the relationship between MS and the concentrations of eight heavy metals was analyzed by using MARS, as in other engineering applications [71][72][73][74][75] because it fits these data better than other models [76,77].…”

Numerical Study on the Variability of Plastic CTOD

“…However, the variability of the material, loading, geometry, temperature, etc., introduces uncertainty in the results. In this context, there are two main procedures to overcome the influence of sources of uncertainties [4]: (i) the use of safety factors, which is the conservative solution usually adopted to accommodate uncertainties, and (ii) performing stochastic analysis, which is often supported by probabilistic fatigue models (e.g., [5,6]), metamodeling techniques (e.g., [7][8][9][10][11][12][13]) and more recently by digital twin approaches (e.g., [14,15]). In the context of stochastic fatigue analysis, a probabilistic fracture mechanics approach to predict the fatigue life of aircraft wing attachment bulkheads was proposed by White [16].…”

“…A probabilistic fatigue life prediction model for multiple site damage in structural components was developed by Kim et al [9], which resort to an extended finite element method coupled with a Gaussian Process metamodel for computational efficiency. Metamodels were developed by Vélez et al [10], to relate the crack tip opening displacement (CTOD) with material properties in high-thickness offshore steel welded joints. The studied material properties (hardness, chemical composition, toughness and microstructural morphology) were shown to be significantly related with the CTOD, also being simpler and cheaper to measure and more available than the CTOD.…”