Session: 02-12-01 Digital Twins of Marine Structures 1

Submission Number: 180438

Real-Time On-Board Estimation of Hull Girder Deformation Using Mode Superposition and Strain Measurement Data 

A number of hull monitoring projects have been conducted in recent years for research purposes. In such projects, multiple strain sensors are typically installed on hull structures to investigate their structural responses during actual operations. Recently, several studies have attempted to estimate the global structural responses of ships by employing digital twins that integrate measured data with numerical models [1]. The authors previously proposed a method to estimate hull-girder deformation from a limited number of strain sensors. This method is based on the mode superposition of hull-girder deformation, and the modal amplitudes are identified by a Kalman filter, referred to as the “Response Kalman Filter (RKF).”

The purpose of this study is to implement the RKF in a strain monitoring system on an actual ship and to validate its basic functionality during operations. The subject vessel is a 216,000 DWT ore carrier. A total of sixteen FBG strain sensors were installed on the vessel: eight on the longitudinal bulkheads near the deck and the remaining eight on the center girder in the double bottom. Eigenvalue analysis was performed in advance using the finite element method, and the eigenvectors required for the RKF were prepared accordingly. Before on-board installation, model parameters such as the eigenmodes to be used and the system and observation noise levels were calibrated using pseudo-measured strain data generated from numerical simulations. The RKF with the calibrated parameters was then integrated into the strain monitoring system, and strain responses on the bottom side were estimated from the measured data on the deck side. The results demonstrate that the RKF can estimate hull-girder responses on board in real time.

In the latter part of the paper, one-year data obtained through the RKF are analyzed to examine its long-term accuracy and to investigate the characteristics of hull-girder responses in actual sea conditions. The analysis reveals correlations among vertical bending, horizontal bending, and torsion of the hull girder. In addition, the predominant deformation mode associated with elastic vibration is examined.

[1] Fujikubo M, Okada T, Murayama H, et al. A digital twin for ship structures—R&D project in Japan. Data-Centric Engineering. 2024;5:e7. doi:10.1017/dce.2024.3.

Presenting Author: Dei Han The University of Osaka

Presenting Author Biography: 2026.04 – Present
Master’s Student, Course of Naval Architecture and Ocean Engineering, The University of Osaka

2022.04 – 2026.03
Bachelor’s Student, Course of Naval Architecture and Ocean Engineering, The University of Osaka

Authors:

Akira Tatsumi The University of Osaka
Dei Han The University of Osaka
Kazuhiro Iijima The University of Osaka