Tubular offshore structures are commonly assembled using welded joints, creating areas of stress concentration and potential fatigue failure. This study focuses on tubular T, Y and K joints, a common offshore structural component. Finite element modeling is used to predict stress concentration factors (Kt) for various loading conditions on the T, Y and K joints. The goal is to calculate Kt values and compare them to existing theoretical solutions from literature. Additionally, the influence of different loading modes (tension, bending) on the Kt values is investigated. By using advanced modeling techniques, this work aims to provide new insight into the behavior of tubular T, Y and K joints connections under realistic offshore loading conditions. The results can help improve design standards and fatigue life predictions for these critical structural joints.

Additive manufacturing has been one of the most used techniques in the recent years because of its capabilities to fabricate complex structures as required by customer and industrial need from a 3D computer-aided design model without the usage of any tooling, dies and heavy machinery makes it a step ahead in the present manufacturing techniques. In the current study the author’s focus on the welding or joining of additive manufactured Polylactic acid (PLA) parts made by Fused Deposition Modeling (FDM). There are several techniques for welding these additive manufactured parts. This study mainly focuses on the joining of 3D printed PLA parts using a 3D pen and investigations on its mechanical properties experimentally. It is a very cheap and effective technique when compared to the other welding methods. This could overcome the drawback of small bed size in most 3D printers by joining smaller parts and it can also be used for repairing the defects caused during the 3D printing. Moreover the experimental testing of the mechanical properties also confirmed that the tensile, flexural and impact strength of 3D pen welded specimens retrieved above 70% of the strength to the original PLA specimen proving it to be a very effective method.