Abstract: A nonlinear finite element model was established to study the compressive mechanical behavior of flexible pipes and the failure mode of reinforced armor layer with the damage protective layer. Firstly, the common damage shapes in engineering were analyzed and classified into four regular damage shapes. Then the undamaged numerical model was analyzed. The deformation process and characteristics of tensile armor layer were elaborated. The force history curves of each layer were compared, and the impact of damage protection layer on the instability of reinforced armor layer failure was summarized. The results showed that the ability to resist radial expansion due to damage is related to the structure's ability to withstand compression. The shape of the damage has an inducing effect on the failure mode of the reinforced armor layer. The ripple failure mode or internal dislocation of the out sheath will instantly strengthen the reinforced armor layer and suppress circumferential buckling. Finally, the common compression failure modes of reinforced armor layers were defined, providing effective references for failure analysis and response strategies in marine engineering.

Key words: flexible pipe, reinforced armor layer, protective layer, damaged mode, compress failure mode