ADWEE: a novel dimension reduction paradigm for high-fidelity hybrid testing of marine flexible structures

Six-degree-of-freedom (6-DOF) physical tests for Tension Leg Platform (TLP) risers face equipment and cost bottlenecks. Existing dimension-reduction methods ignore rotational nonlinearity and energy conservation, causing distorted fatigue assessments. To address this, we propose the Adaptive Dynamic Weighted Energy Equivalence (ADWEE) theory. Based on generalised Port-Hamiltonian dynamics, ADWEE achieves high-fidelity reduction from 6-DOF spatial motions to 2-DOF planar motions. The core innovations include: introducing a virtual gyration arm hypothesis to convert spatial curvature effects; establishing an instantaneous work-energy equivalence mechanism to strictly lock boundary power transmission; and utilising spectral energy adaptive weighting to ensure robustness across sea states. Quantitative analysis and hardware-in-the-loop (HIL) experiments demonstrate that ADWEE achieves exceptional tension equivalence accuracy (R2 > 0.996). Under dominant sea states, the spatial bending moment envelope deviation is <1%, instantaneous power transfer error approaches 0, and dynamic stress correlation exceeds 0.94, accurately synchronising macroscopic energy with microscopic stress. Even in extreme sea states, the physical testbed reproduces actual tension dynamics with an R2 up to 0.997. By significantly reducing testing costs while rigorously reproducing high-frequency nonlinear damage paths, this paper provides a novel dimension-reduction paradigm for high-fidelity physical testing of marine flexible structures.