Study on the axial load recovery characteristics of damaged tensile armour layers in flexible marine cables

• A validated 3D finite-element model is employed to analyze the load recovery length in the damaged tensile armour layer. • Optical frequency domain reflectometry (OFDR) experimental analysis is employed to continuously observe the strain responses before and after damage verifying the applicability of the finite element model. • Key parameters determining the load recovery length of the tensile armour layer under damage. In flexible marine cables, the axial load-bearing capacity of a damaged tensile armour layer tends to recover gradually along its axial length. The aim of this study is to determine the specific impact of tensile armour layer damage on axial load capacity, to analyse the axial mechanical behaviour of both intact and damaged tensile armour layers, and to obtain the recovery length after damage. A typical single-layer helically wound structure is selected as the research object, and a fully three-dimensional refined finite element model is established to simulate local damage and interlayer friction. Additionally, optical frequency domain reflectometry (OFDR) experimental analysis is employed to continuously observe the strain responses before and after damage, verifying the applicability of the finite element model and determining the load recovery length of the tensile armour layer under prefabricated damage conditions. Furthermore, key parameters affecting interlayer friction, including the friction coefficient, external pressure, and helical winding angle, are analysed. The results indicate that as the friction coefficient increases from 0.1 to 0.4, the external pressure increases from 0.25 MPa to 0.75 MPa, and the winding angle increases from 10° to 30°, the load recovery length decreases by 53.0 %, 43.9 %, and 44.3 %, respectively. This study provides scientific support for the operational maintenance of damaged tensile armour layers in flexible cables.