Development of Novel Surrogate Models for Stress Concentration Factors in Composite Reinforced Tubular KT-Joints

Mohsin Iqbal; Saravanan Karuppanan; Veeradasan Perumal; Mark Ovinis; Muhammad Iqbal

doi:10.28991/CEJ-2025-011-04-012

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Mohsin Iqbal
mohsin_22005143@utp.edu.my
Department of Mechanical Engineering, Universiti Teknologi PETRONAS, Seri Iskandar 32610,, Malaysia https://orcid.org/0000-0002-3917-2315
Saravanan Karuppanan Department of Mechanical Engineering, Universiti Teknologi PETRONAS, Seri Iskandar 32610,, Malaysia
Veeradasan Perumal Department of Mechanical Engineering, Universiti Teknologi PETRONAS, Seri Iskandar 32610,, Malaysia
Mark Ovinis School of Engineering and the Built Environment, Birmingham City University, Birmingham,, United Kingdom
Muhammad Iqbal Department of Mechanical Engineering, CECOS University of IT & Emerging Sciences, Phase-6 Hayatabad, Peshawar,, Pakistan

Vol. 11 No. 4 (2025): April

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Circular hollow section (CHS) joints are among the most critical components in offshore jackets, often requiring rehabilitation to maintain structural integrity. The structural stress approach, based on stress concentration factors (SCFs) for hot-spot stress (HSS) calculations, is commonly used to estimate the fatigue life of critical structural elements such as CHS joints. Various empirical models exist for the rapid estimation of SCF in composite-reinforced CHS joints; however, most studies focus on SCF at the crown and saddle positions under uniplanar loading. This limitation reduces their applicability to multi-planar loading conditions, potentially leading to the underestimation of HSS. This study investigates the use of fiber-reinforced polymer (FRP) composites to strengthen CHS KT-joints under complex loading, focusing on reducing SCF and improving fatigue life. A total of 5,429 finite element simulations were conducted to examine the effects of geometric and reinforcement parameters on SCF. The simulation data were used to train artificial neural networks (ANNs), which were incorporated into a computational tool for the rapid approximation of hot-spot stress in FRP-reinforced KT-joints. The application of composites to CHS joints significantly reduces SCF, particularly with an increased number of reinforcement layers, a higher elastic modulus, and an orthogonal fiber orientation to the weld toe. This study presents a novel methodology for developing efficient models to estimate SCF in composite-reinforced CHS joints under complex loading, addressing a key gap in fatigue design for such joints. The developed computational tool enables the rapid calculation of hot-spot stress in CHS joints.

Doi: 10.28991/CEJ-2025-011-04-012

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Development of Novel Surrogate Models for Stress Concentration Factors in Composite Reinforced Tubular KT-Joints

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