Multi-Objective Optimization of Stress Concentration Factors for Fatigue Design of Internal Ring-Reinforced KT-Joints Undergoing Brace Axial Compression

Stress concentration factors are important to determine fatigue life based on the S-N curve methodology, where the lower the stress concentration factor, the higher the fatigue life. In this work, we developed internal ring-reinforced KT-joints, one of the most commonly used joints in the offshore industry, for the most practical ranges with the least stress concentration factors, followed by the formulation of a novel set of parametric equations for determining the stress concentration factors of internal ring-reinforced KT-joints. Using numerical investigation based on a finite element model and a response surface approach with ۸ parameters (λ, δ, ψ, ζ, θ, τ, γ, and β) as input and eleven outputs (SCF ۰° to SCF ۹۰° and peak SCF), the stress at ten locations around the brace was evaluated, since efficient response surface methodology has been proven to give comprehensive and accurate predictions. The KT-joint with the following parameters: λ=۰.۹۵۱۵۱۵, δ=۰.۲, ψ=۰.۸, ζ=۰.۳۱, θ=۴۵.۱۵°, τ=۰.۶۰, γ=۱۶.۲۵, and β=۰.۴۰ had the least stress concentration factor. The KT-joint with the optimized parameters was validated through finite element analysis. The resulting percentage difference was less than ۶%, indicating the applicability of the response surface methodology with high accuracy. Doi: ۱۰.۲۸۹۹۱/CEJ-۲۰۲۴-۰۱۰-۰۶-۰۳ Full Text: PDF

Keywords:

KT-joint , Response Surface Methodology , Stress Concentration Factor , Ring-Stiffeners , Fatigue , Multi-Objective Optimization , Finite Element Analysis.