Marine Structural Mechanics and Integrity LabInha University

Research

Research

Fracture and fatigue are the core of our structural integrity research, supported by nonlinear structural mechanics and research software.

How we work

We begin with the mechanics of damage and failure: how loads are carried, how cracks form and grow, and how cyclic or extreme loading leads to loss of structural performance. Every assessment method, monitoring model, or software tool is grounded in physics so that its predictions remain interpretable and defensible in safety-critical use. Data-driven methods estimate states and parameters of mechanical models; they do not replace those models.

01

Ductile fracture, impact, and crashworthiness of marine structures

This is the lab's longest-running research line. We model how marine structural steels deform, neck, and fracture under the large-strain, dynamic loading of collisions, groundings, and explosions, and we translate those models into engineering assessment procedures.

Current work includes

  • Calibration and implementation of ductile fracture models (Hosford-Coulomb, GTN, BWH instability criteria) for shipbuilding steels, including user material subroutines (VUMAT) for explicit finite element analysis
  • Simulation of ship collision, dropped objects, and underwater explosion response, up to accidental limit state assessment
  • Engineering critical assessment (ECA) and fitness-for-service evaluation of flawed structures

Evidence from the publication record

  1. Cerik BC, Park B, Park SJ, Choung J (2019). Modeling, testing and calibration of ductile crack formation in grade DH36 ship plates. Marine Structures 66: 27–43.
  2. Park SJ, Lee K, Cerik BC, Choung J (2019). Ductile fracture prediction of EH36 grade steel based on Hosford–Coulomb model. Ships and Offshore Structures 14(sup1): 219–230.
  3. Cerik BC, Choung J (2020). Rate-dependent combined necking and fracture model for predicting ductile fracture with shell elements at high strain rates. International Journal of Impact Engineering 146: 103697.
  4. Cerik BC, Park SJ, Choung J (2020). Use of localized necking and fracture as a failure criterion in ship collision analysis. Marine Structures 73: 102787.
  5. Kim H, Cerik BC, Choung J (2022). Effects of fracture models on structural damage and acceleration in naval ships due to underwater explosions. Ocean Engineering 266: 112930.

The full list

Emerging direction. Fracture and defect assessment for alternative marine fuel containment, including low-temperature toughness of cryogenic steels and hydrogen effects on structural materials. This is an emerging research direction rather than an established programme.

02

Fatigue and integrity of floating offshore wind moorings and dynamic power cables

Mooring lines and subsea dynamic power cables are among the least monitored and, statistically, the least reliable subsystems of a floating wind turbine. Direct load measurement is costly, failure-prone, and rarely available along the full length of the component. Our central question is the extent to which the load and fatigue states of these components can be reconstructed from measurements we can realistically obtain, such as platform motions and line-end responses.

Current work includes

  • Physics-based virtual sensing of mooring line tension from platform motion, using Kalman filtering and related state estimators built on lumped-mass line dynamics (funded by Inha University new-faculty research grants, 2025–2027)
  • Shape and curvature estimation of lazy-wave dynamic power cables, where fatigue damage concentrates at the sag and hog bends and the touchdown zone
  • Cross-section mechanics of layered power cable constructions, linking manufacturer-level cable design to the stiffness properties used in global dynamic analysis
  • Long-term fatigue assessment of moorings and cables under site-specific metocean conditions, connecting design load case simulation to damage accumulation

Funded by

  • Physics-Based Virtual Sensing Methodology for Estimating Mooring Line Tension in Floating Offshore Wind Turbines — Inha University New Faculty Research Grant, 2026/3–2027/2
  • Machine Learning-Based Tension Prediction for FOWT Mooring Lines — Inha University New Faculty Research Grant, 2025/3–2026/2

All projects

Evidence from the publication record

  1. Seo JH (2026). Floating offshore substations for offshore wind energy: A review of design challenges, structural integrity, and standardisation gaps. Ocean Engineering 363, Part 1: 126528.
  2. Cerik BC, Huang L (2024). Recent advances in mechanical analysis and design of dynamic power cables for floating offshore wind turbines. Ocean Engineering 311, Part 1: 118810.
  3. Ou B, Cerik BC, Huang L (2025). Seakeeping analysis of catamaran and barge floats for floating solar arrays: A CFD study with experimental validation. Ocean Engineering 326: 120970.
  4. Huang L, Elzaabalawy H, Sarhaan M, Sherif A, Ding H, Ou B, Yang D, Cerik BC (2025). Developing reliable floating solar systems on seas: A review. Ocean Engineering 322: 120525.

The full list

Methods and tools. OpenFAST and OrcaFlex for coupled and line dynamics; our in-house packages CableDyn, CableXsec, and VANE; Bayesian filtering and surrogate modelling in Python. See the software portfolio.

03

Ultimate strength and progressive collapse of ship and offshore structures

The ultimate limit state of a hull girder or a stiffened panel is still computed today with methods whose numerical form has barely changed since the 1980s. We work on the collapse behaviour itself — buckling, load shedding, and interaction between failure modes — and on reformulating classical strength methods in modern differentiable computing frameworks, so that gradient-based design optimisation and sensitivity analysis become natural rather than bolted on.

Current work includes

  • Progressive collapse of hull girders under combined and unsymmetrical loading
  • Ultimate strength of stiffened panels including welding residual stress and deformation effects
  • Differentiable reimplementation of incremental collapse methods in JAX, enabling automatic sensitivities of ultimate strength with respect to scantlings and material parameters

Evidence from the publication record

  1. Kim DK, Sung SH, Song SW, Kim SJ, Prabowo AR, Kim S, Seo JH, Ringsberg JW (2026). A SHAP value method for ultimate strength prediction of stiffened panel: A data-driven tool in engineering. Ocean Engineering 343, Part 1: 123159.
  2. Cerik BC, Choung J (2020). Progressive collapse analysis of intact and damaged ships under unsymmetrical bending. Journal of Marine Science and Engineering 8(12): 988.
  3. Cerik BC (2018). Ultimate longitudinal compressive strength of steel plates with lateral patch load induced plastic deformation. Thin-Walled Structures 122: 416–424.
  4. Cerik BC (2015). Ultimate strength of locally damaged steel stiffened cylinders under axial compression. Thin-Walled Structures 95: 138–151.
  5. Cerik BC, Shin HK, Cho S-R (2013). Probabilistic ultimate strength analysis of submarine pressure hulls. International Journal of Naval Architecture and Ocean Engineering 5(1): 101–115.

The full list

Where this comes from. This thrust continues the incremental–iterative tradition of simplified progressive collapse analysis developed at Newcastle University, whose methods for the elasto-plastic collapse of plates and stiffened panels were incorporated into UK naval structural design standards and the submarine design manual, and were later adopted by classification societies for merchant ships. Professor Seo held a post in marine structures at Newcastle University from 2014 to 2017.

Methods and tools. Nonlinear finite element analysis in Abaqus; Smith-type progressive collapse methods; differentiable numerical implementation in Python and JAX. See the software portfolio.

+

Cross-cutting capability: research software engineering

Every thrust above produces software, and the lab treats that software as a research output in its own right. Packages are developed under version control with automated test suites, continuous integration, and documentation, and are released publicly as the accompanying papers appear. Graduate students in the lab learn this workflow from their first semester, including AI-assisted development practices.

Software & facilities

Partnerships and roles

  • Professor Seo is a member of the ISSC Specialist Committee V.4 — Offshore Renewable Energy for 2025–2028, representing the Republic of Korea.
  • The lab participates as co-investigator in the MOF-funded BEACON marine workforce project (2025–2029) and the MOTIE-funded Digital Shipyard professional training programme (2026–2031).
  • We welcome collaboration with classification societies, shipyards, offshore energy and marine technology developers, and research groups working on structural fracture and fatigue assessment, computational mechanics, or condition monitoring. Contact: jaehoon.seo@inha.ac.kr