Influence of Fracture Toughness on Multi-axial Loading Interaction Criteria for Wrapped Composite Joints
Gisele Cintra (TU Delft - Steel & Composite Structures)
Mathieu Koetsier (TU Delft - Steel & Composite Structures)
Vasileios Mylonopoulos (Tree Composites)
Marko Pavlovic (TU Delft - Steel & Composite Structures)
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Abstract
Wrapped composite joints arise as an innovative solution for joining circular non-welded hollow sections (CHS) in jacket support structures for offshore wind, intending to enhance fatigue performance and consequently reduce weight and costs when compared to traditional welded joints. Due to combined wave and wind loads, these joints are subjected to different multi-axial loading scenarios. Therefore, it becomes fundamental to establish an interaction criterion that accurately predicts the failure behavior provided by the superposition of different load conditions. Preliminary analyses have shown that, for instance, in cases where axial loads act simultaneously with bending moments, the joint resistance is underestimated when considering a linear summation of normalized strength values. Therefore, further studies are needed to determine the optimum interaction criterion exponents. In this context, this paper aims to present the results of an ongoing numerical investigation on the multi-axial load behavior of wrapped composite joints. Based on previous standards, a multi-axial loading interaction criterion is proposed, and a finite-element (FE) model is developed using the cohesive zone model approach. Distinct load cases are applied in a medium-scale X-shaped wrapped joint to evaluate the influence of the fracture toughness parameter on interaction failure criteria exponents. It was concluded that the given exponents do not seem to be affected by the change of interfacial strength and fracture toughness, which represents a valuable finding for the development of future design guidelines.